A comparative clinical study of the safety and efficacy of three toothbrushes. This single (examiner) blind, randomized, 4-week study compared the safety and efficacy of a new electric toothbrush (experimental) regarding plaque removal and reducing gingivitis with two other brushes, an electric brush (control electric) and a manual toothbrush (control hand). Ninety-six subjects with 1) a minimum of 15 suitable teeth in acceptable occlusion; 2) a minimum gingivitis score of 0.9; and 3) a minimum plaque score of 1.8 were entered into the study. The subjects were randomly assigned to one of 3 groups: a control hand group (31 subjects), an experimental group (32 subjects), and a control electric group (33 subjects). Device use instructions were given according to the manufacturer's recommendations. Two examiners separately determined either gingival scores or plaque scores at baseline and 4 weeks. In regard to gingivitis, use of all 3 brushes for the study period showed statistically significant improvements in gingivitis scores (P values less than 0.01) within each of the 3 groups. Between group analyses of covariance showed that of the 3 groups, the control hand group improvement was better than both the experimental and the control electric groups (P less than 0.05). When interproximal gingivitis scores were analyzed separately, similar improvements were noted. Regarding effectiveness of plaque removal during a single brushing event at the initial and final visits, each of the 3 brushes was effective in reducing plaque for every tooth surface scored (P values less than 0.01). However, between group analyses of covariances showed that the experimental group was better than the other two (P less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)


Rinsing with delmopinol 0.2% and chlorhexidine 0.2%: short-term effect on salivary microbiology, plaque, and gingivitis. The aim of this short-term study was to compare the effect of delmopinol HCl 0.2% and chlorhexidine digluconate 0.2% rinses on the development of dental plaque, the healing of experimental gingivitis, and the salivary microbiology. As part of a larger study protocol, 45 healthy males enrolled in an oral hygiene program to upgrade their oral health. For this portion of the study, participants had their teeth professionally cleaned on day 0. The participants then abstained from standard mechanical oral hygiene procedures, but applied a placebo solution twice daily for 2 weeks. At the end of this period the subjects received a second professional cleaning and were then assigned to 2 treatment groups: Group 1 rinsed with 10 ml of delmopinol HCl 0.2% and Group 2 rinsed with 10 ml of chlorhexidine digluconate 0.2% for 1 minute twice daily for the next 2 weeks and continued to refrain from mechanical oral hygiene procedures. At the end of the placebo and active treatment periods 1) saliva samples were taken and cultivated on a series of media; 2) the degree of gingivitis was assessed with gingival crevicular fluid (GCF) and gingivitis index (GI); and 3) the plaque index was assessed and the stainable buccal plaque extension was analyzed planimetrically. No changes in the salivary microbiological counts were detected for the subjects rinsing with delmopinol. Subjects rinsing with chlorhexidine showed significant reductions of anaerobes, aerobes, and S. mutans in saliva. The amounts of GCF and GI were reduced largely to the same extent in both treatment groups. Mean plaque extension was reduced by 52% after delmopinol and 88% after chlorhexidine rinsing.(ABSTRACT TRUNCATED AT 250 WORDS)


The effects of the Nd:YAG laser on in vitro fibroblast attachment to endotoxin-treated root surfaces. The purpose of this study was to evaluate the effects of the Nd:YAG laser on in vitro fibroblast attachment to endotoxin-treated root surfaces and to describe any laser-induced cementum surface alterations. Thirty 4 mm x 4 mm cementum segments were obtained from unerupted third molars. The treatment groups were as follows: 1) control, healthy root segment; 2) non-lased, endotoxin treated; and 3) lased, endotoxin treated. The endotoxin treated roots were soaked in E. coli 055:B5 lipopolysaccharide (556 EU/ml) for 72 hours. The lased, endotoxin-treated root segments were treated with a Nd:YAG laser using a 320 microns contact optic fiber handpiece with an energy setting of 80 mJ at 10 pulses per second for one minute. The root segments were subsequently placed in fibroblast culture dishes for 40 hours and then prepared for scanning electron microscopy (SEM) observation. SEM examination revealed two different types of attachment: flat and round. Flat cells represented firmly attached cells due to well-defined points of attachment and numerous lamellapodia. Round cells possessed few attachment processes and were, therefore, considered poorly attached. The lased, endotoxin-treated root segments had significantly decreased numbers of flat fibroblasts versus the control and non-lased, endotoxin-treated root segments. The absence of flat fibroblasts in the laser treated root segments was a consistent finding. The non-lased, endotoxin-treated root segments had significantly increased numbers of round fibroblasts versus the control and lased, endotoxin treated groups. The lased root segments exhibited surface alterations which included charring, crater formation, cementum meltdown, and tracking.(ABSTRACT TRUNCATED AT 250 WORDS)


Chemical characterization of lased root surfaces using Fourier transform infrared photoacoustic spectroscopy. Recently lasers have been recommended as an alternative or adjunctive therapy in the control and treatment of periodontally diseased root surfaces. The purpose of this in vitro investigation was to characterize the chemical structure of lased root surfaces using Fourier transform infrared photoacoustic spectroscopy (FTIR/PAS). Cementum samples, 6 mm x 2 mm, were cut from the root surface of extracted non-carious, unerupted human molars. The experimental samples were lased with a Nd:YAG laser at an average energy of 80 mJ at 10 pulses per second. Total lasing time ranged from 1 minute 45 seconds to 4 minutes. A non-lased cementum sample served as the control. All spectra were recorded from 4000 to 400 cm-1 using the photoacoustic cell attachment on an Analect RFX-65 FTIR Spectrometer. Photoacoustic FTIR spectra of lased cementum samples showed a decrease in the protein/mineral ratio in comparison to the control. Breakdown of protein at the root surface potentially contributed to an ammonium band at 2010 cm-1. The decreased protein/mineral ratio and the potential surface contamination with protein by-products, may ultimately affect cell reattachment at the cementum surface.


The effect of Nd:YAG laser exposure on root surfaces when used as an adjunct to root planing: an in vitro study. The purpose of this study was to evaluate the effects of Nd:YAG laser treatment on root surfaces in vitro when used alone or in combination with conventional scaling and root planing. The study population consisted of 18 unerupted third molars, each with a 3 mm diameter treatment site outlined on the root surface. Three specimens were randomly assigned to each of 6 different treatment groups: 1) untreated control; 2) root planed only; 3) laser treated only using 1.25 W of energy; 4) laser treated only using 1.50 W of energy; 5) laser treated with 1.25 W of energy followed by root planing; and 6) laser treated with 1.50 W of energy followed by root planing. Following their respective treatment, all specimens were prepared for evaluation by scanning electron microscopy. Specimens from Group 2, root planed only, exhibited a smear layer of scale-like texture with parallel instrument tracks resulting from curet use. Specimens treated by laser only, Groups 3 and 4, featured various surface changes not observed in controls such as charring and carbonization of the cementum surface, randomly distributed pitting and crater formation, and melting of the root mineral phase with subsequent resolidification as porous globules. Those specimens treated by laser followed by root planing, Groups 5 and 6, exhibited surface characteristics similar to those noted in Group 2 specimens. Further, there were areas of exposed dentinal tubules resulting from a "peeling" of the cementum layer. The results of this in vitro study suggest that laser use during root preparation, even at relatively low energy levels, will result in physical changes to the root surface.(ABSTRACT TRUNCATED AT 250 WORDS)


Pneumoparotitis associated with the use of an air-powder prophylaxis unit. A case reporting barotrauma to the parotid gland secondarily to the use of an air-powder prophylaxis unit is presented. Air pressure associated with these units usually exceeds that for air/driven turbines or air/water dental syringes, yet the reported incidence of iatrogenic trauma is very low. Improper angulation in the use of these instruments may result in serious sequellae. Differential diagnosis and physical examination following trauma to the parotid is discussed.


Recurrent peripheral odontogenic fibroma of the attached gingiva: a case report. Peripheral odontogenic fibroma is an uncommon, benign, unencapsulated, exophytic gingival mass of fibrous connective tissue covered with a surface epithelium. Odontogenic epithelium and mineralized material may be found in the mass. A case is reported of a lesion that recurred in the attached gingiva following initial excision. Differential diagnosis of exophytic gingival lesions and post-operative management are also discussed.


Computerized methodology for detection of alveolar crestal bone loss from serial intraoral radiographs. The aim of this study was to develop a computerized measurement system for analysis of unstandardized serial radiographic images. A new approach for estimating the error associated with the determination of alveolar crest loss is described. The study shows that a difference of 0.87 mm in cemento-enamel junction-crest measurement between unstandardized serial radiographs taken within accepted clinic routine is required for a significant loss in crestal bone height. The ability to detect with significance a difference of less than 1 mm in crestal bone height makes the appropriate use of traditional bite-wing radiographs a useful diagnostic tool for the assessment of periodontal maintenance.


Retained "hopeless" teeth: lack of effect periodontally-treated teeth have on the proximal periodontium of adjacent teeth 8-years later. We previously reported the lack of effect periodontally-treated teeth prognosed "hopeless" and retained for 3.4 +/- 1.5 years have on the proximal periodontium of adjacent teeth. We now report our findings for the same group of subjects following 8.4 +/- 0.7 years of "hopeless" tooth retention. Of the 17 "hopeless" and adjacent teeth originally measured in 17 subjects, 14 of the subjects were still available for re-evaluation. Measures used to assess the periodontium of proximal surfaces of adjacent teeth included pocket depths (PD), radiographic alveolar bone level (R-BL), and periodontal ligament space width (W-PL). Treatment for the subjects consisted of surgical therapy (N = 15) and scaling and root planing (N = 2). Of the 14 subjects re-examined, 2 were eliminated due to loss of adjacent tooth reference points and 2 due to extraction of the "hopeless" tooth (N = 10). Differences in measurements (i.e., nonadjacent to "hopeless" tooth value minus adjacent to "hopeless" tooth value) were analyzed using a repeated measures ANOVA. There were no significant differences for PD (P = 0.20), R-BL (P = 0.29), or W-PL (P = 0.16). These data confirm our original findings that retained periodontally "hopeless" teeth do not significantly affect the proximal periodontium of adjacent teeth following therapy.


A histomorphologic study of the effects of periodontal inflammation on the maxillary sinus mucosa. Twenty blocks of human jaws obtained at autopsy and containing maxillary molar teeth with the contiguous maxillary sinus intact were prepared utilizing conventional histopathologic techniques and were studied by light microscopy. The purpose of this investigation was to confirm earlier clinical reports suggesting a close association between human periodontitis and maxillary sinus thickening and to morphologically document the nature of the sinus changes. Seventeen of 20 jaw specimens demonstrated moderate to advanced periodontal destruction with pervasive extension of the inflammatory infiltrate through the alveolar process beyond the apices of the teeth and extending to the region of the antrum. Of the 20 histologic specimens, 10 showed extensive thickening of the sinus membrane, 9 had moderate hyperplastic changes, and only 1 specimen demonstrated a normal appearing sinus. Pathologic changes in the sinus membrane included inflammatory cell infiltration, edema, fibrosis of the tunica propria, mucous-serous gland proliferation, interstitial pseudo-cyst formation, polyp formation, hyalinization of the connective tissue lining, thrombosis of blood vessels, and metaplastic and degenerative changes in the epithelial lining. This study, based on histopathologic changes, suggests an apparent direct relationship between moderate and severe periodontitis of the maxillary molar teeth and pathologic changes resulting in thickening of the maxillary sinus mucosa.


Association between detection of oral Actinobacillus actinomycetemcomitans and radiographic bone loss in teenagers. A 4-year longitudinal study. The aim of the present study was to assess a possible association between radiographic bone loss and presence of Actinobacillus actinomycetemcomitans on the site and subject level over time. Forty-six teenagers with registered radiographic bone loss and 8 controls participated in the study, which began in 1984. In 1986 and 1988 new sets of bite-wing radiographs were obtained and examined for bone loss. Subgingival plaque was sampled from both diseased and contralateral healthy sites in the same individual. Only 15 of the 46 originally diseased sites persisted with bone loss in 1986, and 60% of these sites harbored A. actinomycetemcomitans. Of the 31 "healed" sites, 29% contained A. actinomycetemcomitans. The difference was statistically significant at P less than 0.05. Six of the contralateral healthy sites had developed bone loss during these 2 years and 50% of them contained A. actinomycetemcomitans, while 35% of the remaining contralateral sites harbored A. actinomycetemcomitans. The difference was not statistically significant (P greater than 0.05). The difference between patients with and without persistent bone loss regarding presence of A. actinomycetemcomitans was statistically significant in 1986; however, none of the observed differences were statistically significant in 1988. A. actinomycetemcomitans was found 2 to 3 times more frequently in patients with radiographic bone loss at all examinations than in "healthy" subjects. Detection of A. actinomycetemcomitans on the site level appeared to be a poor predictor of future radiographic bone loss.


Distribution of natural killer cells in periodontal diseases: an immunohistochemical study. We studied the distribution and incidence of natural killer (NK) cells in gingiva affected with adult periodontitis (AP) and rapidly progressive periodontitis (RP) with immunohistochemical methods using antibodies Leu-7 and Leu-11b. The incidence of Leu-7 positive cells revealed no significant difference among mild AP, severe AP, and RP. On the other hand, Leu-11b positive cells were frequently found in severe AP and RP. The accumulation of NK cells reacting with Leu-11b in the infiltrated connective tissue was greater in severe forms of periodontal disease (severe AP and RP) than in mild AP. These results suggest that Leu-11b positive NK cells may play a role in the destruction of tissues in periodontal diseases.


Multi-level statistical models in studies of periodontal diseases. Periodontal data typically have a hierarchical structure, with sites grouped within individuals, and individuals grouped within communities. Also, the occasion may be regarded as another level since the acquired knowledge indicates that periodontal disease activity may vary over time. Conventional statistical tests are based on unilevel analysis of data. However, this approach to statistical analysis is often inconvenient in periodontal research because of the variation in the outcome variables between the various levels in the hierarchy. Lately there have been important developments in the statistical theory which have made available powerful statistical techniques for analyzing multilevel or hierarchical data. This report describes a new approach for analyzing periodontal data and uses an illustrative example to build a model which explains part of the variability in the response variable. The results from this analysis are then compared to results from an earlier report which uses unilevel methods and the findings discussed. The present multilevel approach has several advantages over unilevel methods, mainly due to its statistical validity and efficiency. Further, it permits the incorporation of explanatory variables measured at the site and the subject levels, and those which vary across the time points. Multilevel analyses have a promising potential and are expected to have a significant impact on periodontal research.


Treatment of an osseous lesion associated with a severe palato-radicular groove: a case report. This is a case report that describes the management of a severe periodontal defect associated with a palato-radicular (palato-gingival) groove affecting the maxillary right lateral incisor of a 50 year-old male. The patient presented with pain, gingival swelling, and a 10 mm periodontal pocket on the distopalatal aspect of the right maxillary lateral incisor. The defect was initially treated by scaling and root planing. Several days later a flap was elevated, the osseous defect was debrided, and odontoplasty was performed to eliminate the groove. The root surface was treated with citric acid for 3 minutes, the osseous defect was filled with non-porous hydroxyapatite, a periodontal membrane was placed, and the flap was readapted to the tooth. Postoperative care included systemic (minocycline) and local (chlorhexidine) antimicrobial therapy. The membrane was removed 6 weeks postoperatively and 14 months postoperatively the gingiva appeared healthy; radiographs suggested substantial resolution of the osseous defect and about 7 mm of probing attachment gain was recorded. Further studies are necessary to determine which of the several modes of therapy used to treat this lesion are necessary for success.


Tuberous sclerosis with gingival overgrowth. A case of tuberous sclerosis with gingival overgrowth is presented. A brief literature review and diagnostic criteria of tuberous sclerosis are discussed. The patient had a full-mouth gingivectomy with frequent post-operative maintenance visits. After 6 months, the overgrowth in conjunction with the tuberous sclerosis returned.


Multiple focal pigmented lesions in the maxillary tuberosity and hard palate: a unique display of intraoral junctional nevi. The pigmented conditions located in the oral cavity have a diverse genesis ranging from vascular lesions to exogenous and endogenous pigmentations. In this report we have documented the unusual occurrence of multiple intraoral junctional nevi in a patient. A review of the patient's past dental records revealed that 2 of these lesions were first noticed 8 years earlier; however, no efforts were made to identify the nature of the pigmentations. Removal of 4 lesions and subsequent histopathological analysis revealed the presence of junctional nevi. This case illustrates the importance of a thorough clinical and histological work-up when dealing with pigmented lesions in the oral cavity. The excision of all suspected oral nevi is warranted because they cannot be clinically differentiated from other pigmented lesions, including oral melanoma. In addition, the potential of junctional nevi to undergo malignant transformation in the oral cavity is undetermined.


The importance of timing in melatonin administration in a blind man. An 18-year-old blind man suffered from chronic sleep disturbances associated with daytime fatigue and excessive daytime somnolence. After two unsuccessful treatment regimens with 5 mg and 10 mg melatonin administered at bedtime (2200-2230), a third regimen of 5 mg melatonin administered at 2000 for 3 weeks resulted in a successful resolution of his sleep disturbances. We suggest that the efficacy of melatonin in ameliorating sleep disturbances because of alterations in circadian rhythmicity may be dependent on the time of administration.


Circadian rhythms of plasma melatonin in the ruin lizard Podarcis sicula: effects of pinealectomy. Plasma melatonin was measured in lizards (Podarcis sicula) at six different times of day under conditions of constant temperature and darkness. Intact animals showed a circadian rhythm of melatonin with a peak in the subjective night of 207 pg/ml (median) and a trough during the subjective day that was below the minimum detection level of the assay (50 pg/ml). Pinealectomy abolished the circadian rhythm of plasma melatonin; median levels were near or below the minimum detection level at all times sampled. The data suggest that the pineal is the only source of rhythmic blood-borne melatonin in Podarcis sicula, and are consistent with the hypothesis that changes in the free-running period of the locomotor rhythm induced by pinealectomy in this species are due to withdrawal of rhythmic melatonin from the blood.


Administration of melatonin into the mediobasal hypothalamus as a continuous or intermittent signal affects the secretion of follicle stimulating hormone and prolactin in the ram. The biological effects of administering melatonin into the mediobasal hypothalamus (MBH) was documented in adult Soay rams using two delivery systems: (1) microimplants in the MBH delivering melatonin continuously and (2) microdialysis probes in the MBH delivering melatonin intermittently as a daily timed infusion. The experimental protocol was to precondition rams to long days (LD 16:8) for 10 to 12 weeks, and then introduce the exogenous source of melatonin by implantation or infusion. Sixteen rams were divided equally into four treatment groups: (a) microimplants in the MBH, (b) microdialysis probes in the MBH, (c) empty microimplants in the MBH to act as sham-operated controls, and (d) no surgery to act as unoperated controls. The microimplants consisted of 22-gauge stainless steel cannulae with melatonin fused inside the tip and were placed bilaterally in the brain for 14 weeks. These implants had previously been shown to release melatonin at a relatively constant rate when incubated in buffered saline at 37 degrees C (3.42 +/- 0.42 micrograms/24 hr, mean +/- SEM, 1-10 weeks) and to produce a localised concentration of melatonin when implanted in the brain (localised to within 1 mm of the center of the implant). The microdialysis probes were also 22-gauge cannulae with a 3 mm membrane (Biotech). They were placed bilaterally into the MBH, connected to two portable syringe drivers secured to a backpack. Melatonin was infused daily for 10 hr (estimated delivery: 0.5 microgram/hr) starting in the mid-light phase to produce a long-duration intermittent melatonin signal. Technical problems limited the period of infusions to 8-10 weeks with minor interruptions. Animals from all groups were maintained on long days, and the observations extended for a period of 28 weeks. The melatonin implants placed in the MBH induced a premature increase in the blood concentrations of FSH and growth of the testes. This treatment also induced a marked decrease in the plasma concentrations of prolactin and the earlier development of the long winter pelage. These changes were reversed after the end of treatment with a decline in the plasma concentrations of FSH and regression of the testes, and an increase in the concentrations of prolactin and moult of the winter pelage. Daily infusions of melatonin from the microdialysis probes in the MBH produced qualitatively similar, but less marked responses. The overall results illustrate that the administration of melatonin into the MBH, either continuously or intermittently, to extend the duration of the daily melatonin signal, induces multiple short-day responses.(ABSTRACT TRUNCATED AT 400 WORDS)


A center of nursing excellence: supporting the professional practice environment. The Center of Nursing Excellence is a unique, multifaceted program that promotes the professional practice environment. The Center provides programs and services in six areas: career planning and development, nursing practice review, research and grants support, scholarly affairs, nursing outreach, and nursing resources. The Center serves as a resource to nurses at St. Louis Children's Hospital and in the nursing community at large.


Teenagers' knowledge of the acquired immunodeficiency syndrome and associated risk behaviors. Adolescents are now recognized as being at high risk for contracting the human immunodeficiency virus (HIV), the presumed cause of acquired immunodeficiency syndrome (AIDS). This article reports the findings of a survey that examined AIDS knowledge, risk behaviors, and informational sources for AIDS in a group of suburban New Jersey high school students (N = 152). This group had knowledge of HIV and its transmission, but results indicated that students also participated in behaviors considered "risky" for the transmission of HIV. These behaviors included unprotected sexual intercourse (40% of sexually active males) and sexual intercourse with multiple partners over a period of time (23% of sexually active males).


Failure to thrive: a parent-infant interaction perspective. The purpose of this study was to prospectively study inpatients admitted for failure to thrive during their first year of life. Twelve infants with failure to thrive were studied and compared with 17 healthy controls. Mothers and infants with nonorganic failure to thrive scored lower on the Nursing Child Assessment Feeding Scale, reported more change in their lives, and less social support. The need for further research is discussed and suggestions for beginning level interventions are made.


Children's knowledge of internal anatomy: conceptual orientation and review of research. Children's understanding of health and illness is influenced by their knowledge of internal anatomy and physiological functioning. This article provides a comprehensive review of studies of children's knowledge of internal anatomy, one component of internal body image. Consistencies, controversies, and methodological issues that emerge across the studies are discussed. A conceptual framework for the development of children's internal body image is presented. The framework posits relationships between cognitive development, health status, knowledge of internal body image, and understanding of physiological functioning. Future studies are needed to test and refine the conceptual framework and to develop interventions to facilitate children's internal body image.


Respite care services to caretakers of chronically ill children in California. Caring for chronically ill and/or technology-dependent children at home can be emotionally, physically, psychologically, and financially exhausting for the caregiver. Caregivers require temporary relief from the burden of day-to-day care of these children. Respite care offers the opportunity for this relief. A study was conducted to survey the availability of respite care for chronically ill and technology-dependent children in California. Survey findings from 45 agencies indicated that 38% provided respite care for chronically ill and/or technology-dependent children. Fifty percent of agencies provided care for less than 10 chronically ill and/or technology-dependent children per year. Major problems associated with provision of respite services were inadequate reimbursement and insufficient request for services.


Infant stimulation during hospitalization. Stimulation is essential to the development of infants and children. They are developing skills related to gross motor, fine motor-adaptive, language, and personal-social functioning. Hospitalization can disrupt the developmental process for infants, even those without pre-existing developmental delays, if intervention is not provided. Hospitalized infants are often subjected to an overabundance of meaningless stimulation or understimulation. Nursing needs to insure provision of meaningful stimulation to help alleviate the effects of hospitalization. Parents and/or significant others need to be included whenever possible. A suggested infant stimulation program for hospitalized infants is presented. Practicality for the pediatric clinician facilitates easy intervention.


Characteristics of caregivers that promote children's development in day care. Most available evidence on day care suggests that characteristics of the caregiver are the key components of high-quality child care. Yet, this fact is rarely appreciated by parents or policy makers. As primary health care providers, nurses can educate parents, caregivers, and policy-makers concerning the broad array of day-care features, including caregiver characteristics that should be considered. This article provides a review of the research on characteristics of caregivers that are found in high-quality day care and describes how these factors facilitate optimal development in young children. From the research findings, implications for nursing practice at the family, community, and national levels are identified.


Pediatric nursing in the United Kingdom. Child health matters remain low on the government agenda, and present reforms of the NHS are overtly concerned with financial aspects rather than the quality of care. Pediatric nurses must therefore become more assertive and pro-active in their role as advocates for children and their families. However, pediatric nurses are extremely fortunate in the UK because they have (a) a nurse education system that has always recognized that the nursing needs of children are different to those of adults, (b) the opportunity to work with medical and voluntary organizations committed to improving children's health, and (c) a professional organization that is not only large and powerful, but since 1984 has been committed to advancing the art and science of pediatric nursing. It employs a full-time adviser to assist its members and publishes the only pediatric nursing journal. Pediatric nurses have assisted in advancing the art and science of pediatric nursing with caring for children and their families in a holistic fashion, with families supported and participating in their child's care. But there are still many opportunities to improve the quality of health care to children and their families. Quality caring is what children and their families want and deserve, but is not as easy to measure as quantity care. At a time when in so many countries, health service managers concentrate on quantity, pediatric nurses must use every opportunity to shape the health policy of their nation for the benefit of children. We all live in interesting times and it would be interesting to see what we make of them on behalf of children.


On the special status of "ego threats".

On the special status of "ego threats". This article comments on a recent article by Heatherton, Herman, and Polivy (1991) in which they suggest that ego threats are a prerequisite to affectively induced disinhibition of food intake in restrained eaters and current dieters. In contrast, the present review suggests that mood induction procedures that involve no apparent threat (e.g., viewing a frightening film) can also prompt disinhibition in restrained eaters. Thus, any mood induction procedure that does not directly physically threaten the S may disinhibit restrained eaters. It is concluded that recommendations to focus future research on ego threats are premature and may serve to obscure the mechanisms by which changes in affective state influence food intake in dieters.


An assessment of cadmium toxicity on cytochrome P-450 and flavin monooxygenase-mediated metabolic pathways of dimethylaniline in male rabbits. Cadmium is an environmental pollutant and its effect on the in vitro metabolism of N,N-dimethylaniline (DMA) using male rabbits was investigated. Activities of cytochrome P-450 and FMO-dependent monooxygenases were studied using hepatic microsomes. Following CdCl2 (i.p.) administration (6 mg/kg/day for 6 days), both DMA-N-oxidation and DMA-N-demethylation decreased by 86%. The effects of CdCl2 on the phenobarbitone (PB)-induced form of P-450 were also studied. Intraperitoneal pretreatment of rabbits with PB (5 mg/kg/day for 5 days) increased N-demethylation by 82%, while N-oxidation decreased by 49%. Both reactions decreased significantly on additional treatment with CdCl2. Promethazine (5 mg/kg/day for 5 days) did not produce any change in the activities of either enzyme. The enzymes remained unaffected by CdCl2 treatment in promethazine-pretreated animals thus confirming its role as a hepatoprotective agent.


The etiological role of diet, smoking, and drinking habits of patients with esophageal carcinoma in Turkey. Esophageal cancer has a known high incidence in areas adjacent to the Caspian Sea and in northeastern Turkey. This study compares the incidence of esophageal cancer in Bursa (northwestern Turkey) with an age-matched control population. Factors associated with esophageal cancer and significantly at variance with controls include: age over 70, low income, smoking more than one pack of cigarettes per day, and low vegetable and fresh fruit intake.


The influence of soil components and drinking water on the appearance of cancer: a review. The author reviews the relationships of soil and reused water with the occurrence of cancer. The effect of the soil composition on the emergence of geocancerologic diseases such as cancer of the stomach, esophagus, urinary tract, breast, bronchus, pleura, and bone is analyzed. The study also reviews geocancerologic diseases linked with the use of recycled waste water.


Treatment of Morton's neuroma as a nerve compression. The role for neurolysis. The almost universal surgical approach for the treatment of Morton's metatarsalgia is to resect the neuroma through a dorsal incision. Considering that the mechanism for the metatarsalgia is chronic repetitive compression of the common plantar digital nerve between the metatarsal heads, this report explores the use of neurolysis in five patients with 11 involved nerves. In surgery, the intermetatarsal ligament is divided, intrinsic fibrosis is released, and the epineurium is opened. The mean follow-up period is 33 months. Complete pain relief was achieved in four of the five patients, with the fifth patient, 13 years after a crush injury to the foot, achieving good pain relief. All five patients resumed their usual jobs and athletic activities. One patient wears sneakers instead of regular shoes. The patient with the crush injury wears custom-made shoes.


Alterations in the hematological profile in rat following whole body gamma radiation with and without venoruton pretreatment. The radioprotective effect of venoruton [O-(beta-hydroxyethyl)-rutoside] has been assessed in the hematological profile of Swiss albino male rats subjected to a single dose of 300 rads whole body gamma radiation. The results showed that the severity of the radiation-induced abnormalities in the red and white blood cells is significantly lessened by venoruton administered prior to radiation exposure.


Effect of insole material on force and plantar pressures during walking. Twelve subjects between the ages of 24 and 35 years walked barefoot over a pressure platform with the following insole materials placed directly on top of the platform: 1) PPT, 2) Spenco, and 3) Viscolas. Maximum vertical force, vertical force-time integral as well as maximum plantar pressure data were collected for the rearfoot, midfoot, and forefoot regions. The results were not significant for maximum vertical force and vertical force-time integral among the three insole materials when compared to barefoot-only walking. There was, however, a significant reduction in forefoot maximum plantar pressure among the three materials compared to barefoot-only walking. In the rearfoot region, a reduction in maximum plantar pressure was seen only with PPT and Spenco.


Postoperative physical therapy for podiatric surgery. The authors discuss several rehabilitation protocols for different surgical procedures on the foot. These are designed to be used as a reference for the podiatrist and therapist. In addition, various modalities are highlighted to familiarize the practitioner with their uses. Physical therapy can aid in decreasing the recovery period from foot surgery, which is particularly advantageous for the athlete.


Hematological lesions in rat following heavy alcohol ingestion. Hematological fluctuations following large alcohol oral administration (2 mL per animal per day) in rats were monitored at intervals ranging from 10 to 22 weeks and the findings were compared to those in control animals that were fed sucrose isocalorically. Following alcohol ingestion, there was a significant decrease in the total blood cellularity at all treatment intervals. A fall in the erythrocyte count per millimeter3 was accompanied by decreased hematocrit values and hemoglobin levels in the alcohol-treated animals. On the other hand, the MCV and MCH values were significantly elevated after alcohol ingestion. Despite overall leukopenia observed after alcohol ingestion, there was a significant increase in the absolute neutrophil count. The absolute lymphocyte count, however, fell significantly in the alcohol-treated animals. Eosinophils and basophils were not significantly altered by alcohol toxicity.


Chemical inactivation of aflatoxins in peanut protein ingredients. Aflatoxin contamination of peanuts has posed a threat to the peanut industry in utilizing peanuts as a source of a low-cost protein ingredient for food and feed. Although the best approach to containing the aflatoxin problem in peanuts is prevention, it appears that chemical inactivation of aflatoxin in contaminated raw material provides the best means to salvaging the contaminated material. Several chemical reagents have been investigated for their efficacy in destroying aflatoxins present in raw peanuts and defatted peanut meal. Using certain oxidizing agents such as NaOCl, H2O2, and benzoyl peroxide; bases such as ammonia, methylamine, and calcium hydroxide; and aldehydes such as formaldehyde, contaminated raw peanuts or defatted peanut meal have been demonstrated to yield peanut meals, protein isolates, and concentrates having trace amounts or nondetectable levels of aflatoxins. Processing conditions for inactivating aflatoxins using these chemicals were investigated. The chemical treatments had little effect on the physiochemical properties of the detoxified protein product. The advantages and disadvantages of using these chemicals for inactivation of aflatoxins are discussed.


Synovial osteochondromatosis. A brief review. An unusual clinical finding is presented with a brief review of the literature. Synovial osteochondromatosis is typically a benign process involving metaplasia of the synovial intima and the formation of cartilaginous nodules that may eventually become ossified. Synovial osteochondromatosis should always be considered as a differential diagnosis whenever a patient presents with pain, swelling, and loss of function at or around a joint. Chondrosarcoma has been misdiagnosed, leading to radical and unnecessary amputation, because synovial osteochondromatosis has not been considered. Alternatively, synovial osteochondromatosis may degenerate to or be associated with a malignant process. When radiographs or more sophisticated investigative procedures, such as magnetic resonance imaging, fail to provide a conclusive answer, histologic findings provide the definitive diagnosis.


Bond versus rebond strengths of three luting agents for resin-bonded fixed partial dentures. Recently, new luting materials have been claimed to have adhesion to metal and tooth structure. This study determined if rebonding the specimens affected their tensile bond strength. Ten samples each of Rexillium III metal cylinders (12 x 6.3 mm) were bonded and rebonded with Comspan Panavia and Super-bond materials. The film thickness was controlled with a micrometer device at 20 microns. The samples were stored for 24 hours in deionized water at 37 degrees C and were then thermocycled for 24 hours and tested for tensile failure on an Instron testing machine. A stereomicroscope was used to determine adhesive/cohesive failure. The results showed a significant difference at p greater than 0.01 in tensile bond strengths (bond versus rebond strength) for all three luting agents. Most of the failures were adhesive in nature.


Cast metal resin-bonded dental restorations: effect on the resin-to-metal bond of storage conditions before cementation. Cast metal resin-bonded restorations are often stored in the laboratory or dental practice/office before they are fitted in the mouth. This study investigated the effect of the storage conditions of such restorations on the tensile bond strength of a resin cement. Sixty cylinders were cast in nickel-chromium alloy (Wiron 88). Their bonding surfaces were sandblasted, cleaned ultrasonically in distilled water, and air dried. Groups of 10 cylinders were stored for 10 days in an office environment as follows: in an open container, in a sealed polyethylene bag, in a plastic pot, in distilled water, or in acetone. A control group was used immediately for bonding. Each cylinder was bonded with a thin film of resin (Panavia Ex) to a freshly prepared disk of the same alloy. After 24 hours in water at 37 degrees C, the assembly was loaded under tension to failure. The results indicated that storage in an open container should be avoided and that restorations can best be protected by storage in distilled water.


Bonding fixed prosthodontic composite resin and precious metal alloys with the use of a vinyl-thiol primer and an adhesive opaque resin. Adhesive bonding of a light-cured fixed prosthodontic composite resin joined to silver- and gold-based alloys was investigated with the use of a metal primer and an adhesive opaque resin. The primer contained an adhesive bonding promoter for precious alloys, 6- (4-vinylbenzyl-n-propyl) amino-1, 3, 5-triazine-2, 4-dithiol (VBATDT). The cast metal specimens were alumina-blasted and primed with VBATDT acetone solution. A self-curable 4-META/MMA-TBB opaque resin was used to bond the primed metals and a light-cured composite resin. Prepared specimens were thermocycled in water and bond strengths were determined. The shear bond strengths after 100,000 thermocycles (4 degrees C to 60 degrees C for 1 minute) were 28.4 MPa for Ag-Pd-Cu-Au alloy and 20.8 MPa for type III gold alloy. This simple method may be used to bond silver or gold alloy and light-activated fixed prosthodontic composite resin.


Clinical evaluation of a composite resin system with a dentin bonding agent for restoration of permanent posterior teeth: a 3-year study. This study evaluated the clinical performance of a visible light-cured small particle bimodally filled hybrid condensable composite resin system that included a dentin bonding agent compared with an amalgam alloy in class II restorations of permanent teeth. A total of 108 restorations were placed in 34 patients. Fifty-three composite resin and 55 amalgam restorations were inserted. Each restoration was evaluated immediately after placement and then on an annual basis for a 3-year period using the Public Health Service (PHS) criteria. In addition, the Moffa-Lugassy scale was used to measure the loss of material on the occlusal surface of these materials. One hundred percent of the resin and amalgam restorations were evaluated, measured, and reasons for replacement were recorded over the 3-year period. There was no significant difference (p greater than 0.05) in the clinical performance of the composite resin and the amalgam when evaluated by the PHS criteria. Analyses of wear at each of the three annual recall periods did not reveal any significant difference (p greater than 0.05) between the two restorative materials when measured by the Moffa-Lugassy scale.


Effect of laser-etch on bond strengths of glass ionomers. This study evaluated the bond strength between glass ionomer cements and laser-etched dentin. Extracted human molars were sectioned sagittally, creating a flat surface. Samples were shear tested on an Instron testing machine, and mean bond strengths were recorded; statistical analyses indicated no significant differences between the Ketac cements. The bond strengths of both Ketac cements were significantly decreased when applied to laser-etched dentin, but bond strengths of Fuji-II were substantially elevated compared with the control values.


Tensile bond strength of repaired amalgam. This study evaluated the tensile strength of repaired high-copper amalgams and analyzed the different treatments of the amalgam interface prior to repair. One hundred specimens were divided into 10 groups: group 1 was left intact and was considered as the control group. In groups 2 through 8, the specimens were sectioned into halves after 10 days and were reconstructed with new amalgam. Groups 9 and 10 were condensed with time intervals of 15 minutes and all specimens were subjected to tensile loads in a Universal Testing Machine. The tensile strengths at the junction between old and new amalgam ranged between 50% to 79% of those of the control group and verified that the same type of amalgam and uncontaminated interfaces had higher strengths. The results also suggested that if an amalgam repair is anticipated, additional retention is critical to the longevity of the restoration.


Tooth contacts in eccentric mandibular positions and facial morphology. Correlations between facial morphology and tooth contacts in excursive mandibular positions were studied in 75 men aged 20 to 33 years. The morphology of the dentition was verified on dental casts and the face was measured by use of roentgen cephalometry. No correlation was observed between facial morphology and the number of tooth contacts in the retruded position; however, wide dental arches and jaws displayed many contacts on protrusion. Numerous contacts on the functional side in group function were noted in individuals with a facial morphology associated with distal occlusion, such as Angle class II, division 1. Wide dental arches were associated with multiple functional-side contacts whereas tooth contacts on the nonfunctional side were related to the inclination of the mandible. A "long-face" morphology was related to contacts on the nonfunctional side. There was a negative correlation between the extent of the overbite (vertical overlap) and the number of tooth contacts on the nonfunctional side.


Pulpal evaluation of teeth restored with fixed prostheses. The literature demonstrates that each of the elements of crown fabrication involves possible and probable insult to the pulpal tissues of the tooth. Preparation of the tooth can result in pulpal inflammation or even burn lesions. The impression technique can result in reduction of the odontoblastic layer caused by drying of the dentin. Temporary coverage of the preparation involves the use of self-curing resins and temporary cements, both of which can irritate the pulp. The final restoration is attached with cements that are often implicated in pulpal irritation. Dental caries and the procedures necessary to remove it and restore the tooth before preparation for a fixed prosthesis can injure the pulp. This study was done to evaluate the effects of complete coverage fixed prosthetic restorations on the dental pulp. A recall letter was mailed to 1221 patients who had received a fixed partial denture or single crown during the years 1984-1988. One hundred thirty patients were examined. Each tooth was evaluated for pulpal health, periodontal integrity, and clinical acceptability of the restoration. Of the 603 teeth examined, 166 had undergone root canal therapy before placement of the restoration, leaving 437 that were crowned while vital. Of these, 25 (5.7%) were in need of root canal therapy or had undergone root canal therapy after cementation of the fixed prosthesis.


Temperature extremes produced orally by hot and cold liquids. Thermocycling in vitro is a common way of testing dental materials to aid in establishing suitability for in vivo use. There is no standard temperature range for dental material thermocycling. This research attempts to establish an appropriate temperature range by measuring extremes of temperature achieved orally in human volunteer subjects. By using an intraoral digital thermometer probe, 13 human subjects were observed as they drank very hot and cold liquids. The temperature extremes produced intraorally were measured and adjusted for possible error. The results of this study suggest that a range of 0 degrees to 67 degrees C may be appropriate for dental material thermocycling.


A comparative study of the fit and retention of interocclusal splints constructed from heat-cured and autopolymerized polymethylmethacrylate. Fifty-three subjects each had a single Michigan splint constructed of either heat-cured or autopolymerized polymethylmethacrylate. The choice of material was decided randomly. A blind assessment for fit and retention was used on a three-point scale. Fit and retention were apparently unaffected by the material used. Thirteen percent of splints were unsatisfactory for clinical use (poor fit or retention) and this was also independent of material. A small number of splints contained structural faults (voids, porosity, or cracks) that may shorten the clinical life of these restorations; 9 of 12 such faults occurred in the autopolymerized group. Previous research has shown that conventional heat-cured polymethyl-methacrylate has superior properties compared with autopolymerized resin. In the absence of differences in accuracy of fit or retention, a heat-cured material is therefore advised where splints are intended for long-term clinical use.


Comparison of the intercondylar distance and the interfacial width as used with the electronic pantograph. The electronic pantograph (Pantronic) records mandibular movements and computes the articulator settings. The Pantronic pantograph does not determine the intercondylar distance but approximates it from the interfacial width at the condyles. An average distance of 12.5 mm is subtracted from each side to determine the intercondylar distance. This study recorded 45 patients' articulator intercondylar distances that had been set from a mechanical pantograph and they were compared with the Pantronic's approximation. The difference between the interfacial width and the actual intercondylar distance was 15.1 mm on the right side and 14.9 mm on the left side. A numerical value of 15.0 mm was statistically superior to the Pantronic's 12.5 mm in estimating the average distance between the intercondylar distance and the surface of the skin at the condyle. No statistically significant difference was found between the differences of interfacial width and intercondylar distance values for men and women (p greater than 0.05). The mean intercondylar distance was 56.5 mm on the right side and 56.7 mm on the left side. A statistically significant difference was found between the mean intercondylar distances of men and women (p less than 0.05).


A reliable index for correct positioning of precision attachments into an existing overdenture. Limited space over abutment teeth may make incorporation of a precision attachment system within an existing overdenture technique sensitive. A special diagnostic index can be made to depict the available space within the prosthesis over the abutment teeth. This index is critical to determine the feasibility of attachment incorporation, as well as the selection and correct positioning of an appropriate attachment system. A method to improve predictability for precision attachment incorporation into an existing overdenture is described.


Computer-aided evaluation of occlusal load in complete dentures. A computerized diagnostic system was tested for its capability to evaluate the occlusal equilibrium of complete dentures. Its electronic sensor foil was calibrated to intraorally compute a load index for the left and right sides of the denture. The index is calculated by the measured force and number of occlusal contacts. Perfect equilibrium is given by a ratio of load left-to-load right of 1:1. Centric occlusion of complete dentures was examined before and after remounting. A good correlation between load index and the occlusal relationship on the articulator could be observed. The system appears to be suitable for verifying the need for occlusal adjustment. However, improvements concerning the hardware and software are necessary.


A technique for making an esthetic maxillary complete denture surgical stent. A technique for making an esthetic complete denture as a surgical stent to be used in conjunction with hydroxyapatite augmentation surgery of the maxillary arch is presented. The technique involves the use of an articulator, a remount jig, and duplication of a surgically prepared cast.


A socioeconomic comparison of patients receiving prostheses in a two-tier delivery system. It has been theorized that the legalization of providers of denture care other than dentists would make dentures more affordable to and therefore more often obtained by individuals of lower socioeconomic status. The delivery of dental prostheses by nondentists (denturists) has been legalized in Arizona, Colorado, Idaho, Maine, Montana, and Oregon. This study compares the socioeconomic and utilization patterns of two groups of patients receiving prostheses: (1) those whose prosthetic services were provided by dentists and (2) those whose services were provided by denturists. The sample included 135 participants; 31 individuals with 54 prostheses made by denturists and 104 individuals with 165 prostheses made by dentists. Application of the chi-square test and the Hollingshead Two-Factor Index of Social Position revealed no statistically significant correlation, (p less than 0.05) between the provider-based groups and standard socioeconomic variables. The history and pattern of choice of provider as well as level of satisfaction were also remarkable for the similarity displayed by the two groups. It would appear that the two groups are actually one homogeneous group served by two levels of providers.


Sonographic measurement versus mapping for determination of residual ridge width. To achieve long-term success of dental implants, evaluation of the dimensions of the resorbing alveolar process must be accurate because an implant should be surrounded by at least 1 mm of bone. Estimating the thickness of bone is more difficult because the mucosal contour can mask the actual dimension of the residual ridge. With ultrasound, it is possible to analyze and visualize the diameter of maxillary or mandibular residual ridges. Data obtained from ultrasound measurement of residual ridges were compared with the data from ridge mapping with the Wilson bone caliper and the Spoerlein caliper. The ultrasound measurement produced nearly the same data at all measurement points as ridge mapping. Ultrasound also provides exact information about the location of the mental foramen and the maxillary sinus. By using all three methods the initial stage of implant treatment can be planned.


Determining the force absorption quotient for restorative materials used in implant occlusal surfaces. It has been hypothesized that the type of material used to form the occlusal surface of restorations retained by dental implants may impart a "dampening effect" to the bone-implant interface. This study compared the force transmitted to human bone by gold, porcelain, and resin occlusal surfaces in a simulated implant occlusal rehabilitation. A Branemark self-tapping implant was placed in a human cadaver mandible with a stacked three element strain gauge cemented to the lingual cortical plate. An Instron testing machine was used to apply an axial force, through a peanut sample, to a restoration that contained interchangeable occlusal surfaces. Applied force was divided by recorded microstrain at the bone-strain gauge junction to derive a calculated ratio, or force absorption quotient. No statistically significant difference of the force absorption quotient between the occlusal surfaces of gold, porcelain, and resin was observed.


Fabrication of bolus compensators used in the treatment of irregular tissue surfaces in radiation therapy. Radiation treatment involving irregular surfaces of facial topography often causes difficulties for the radiation oncologists. The isodose curves normally used become skewed, thereby making treatment planning more complex. A simple and useful technique is presented describing the use of dental materials to make a bolus compensator to aid in radiation therapy of nonplanar surfaces. This technique will allow the radiation oncologist to treat these patients in a most efficient manner. The materials needed are readily available to the dentist and are easily handled.


An acrylic resin core for processing silicone facial prostheses. A technique is presented for making an acrylic resin core for processing silicone facial prostheses. This technique ensures a durable core that can be used to make multiple prostheses. The core resists fungal growth during storage and creates a smooth, easily cleanable internal surface for a facial prosthesis. The core also permits a controllable thickness and therefore a lighter prosthesis.


Stabilization of an interim obturator prosthesis using a denture duplicator. Concomitant radiotherapy and chemotherapy given within weeks after major surgical procedures may require that an interim obturator prosthesis be worn for extended periods of time. Interim reline materials used in fabricating the interim obturator prosthesis may become rough and difficult to clean. With a Lang denture duplicator it is possible to easily convert an interim obturator prosthesis to an all acrylic resin prosthesis. A technique is described for this procedure.


A mold technique for orbital prostheses. This technique describes a method for making maxillofacial prostheses with tissue undercuts that allows trial closure for esthetic characterization. The finish line is placed on the external eyelid to facilitate final trimming of the prosthesis.


Oral commissure expansion prosthesis.

Oral commissure expansion prosthesis. An expansion prosthesis to stretch commissures and fibrotic muscles is often essential for patients recovering from head and neck trauma or burns. The prosthesis is easily made in one appointment using Triad resin and a 7 mm expansion screw. Depending on the frequency of use, varying degrees of opening of the jaws can be obtained. The prosthesis is inexpensive to make and can easily be modified as needed. It is convenient for use because the patient controls the pressure that is applied by the prosthesis.


Microwave-cured tracheostoma vents.

Microwave-cured tracheostoma vents. This article describes a technique of making custom flexible and combined flexible/rigid tracheostoma vents. The combined flexible rigid tracheostoma vent provides a flexible material that is nonirritating in the peristomial region and maintains a patent tracheostoma by the rigidity of the hard acrylic resin section. The flexible tracheostoma vent can be easily inserted and is more comfortable than the rigid commercially available tracheostomy tube. The use of microwave-cured materials permits fabrication during a single visit. The steps involved in the fabrication of the tracheostoma vents are simple and require no elaborate laboratory equipment.


Influence of tooth contact on the path of condylar movements. The correlation between condylar inclination and tooth guidance was tested by comparison of recordings of condylar movement in right and left parasagittal planes during lateral excursion, opening, and protrusive movements in 13 subjects with temporomandibular joint (TMJ) clicks and 15 subjects without TMJ clicks. The characteristic tracing of mandibular movements at the condyle with tooth-guided versus non-tooth-guided conditions were investigated by use of a computerized Axiograph graph. The generated tracings of each subject were graphed and analyzed to calculate the horizontal condylar inclinations as related to the axis orbital reference plane. Information from a standardized questionnaire provided evidence of a definite correlation between the presence of TMJ clicking and a specific prior medical event (tonsillectomy). The data from computerized tracings of all subjects revealed no significant difference (p 0.05) in the mean angles of condylar guidance at any of the millimeter intervals examined regardless of whether the craniomandibular contact was an articulation of natural teeth or an articulation of maxillary natural teeth against a tray clutch. These results do not suggest that dynamic interarch tooth guidance or the change in vertical dimension reflect a significant alteration in the recordings of condylar guidance in clicking or nonclicking groups.


Edentulous position of the temporomandibular joint. Two bilateral Schuller's position radiographs were made of 10 edentulous patients with complete dentures. In one radiograph, the complete dentures were in place in centric occlusion. For the other radiograph, the complete dentures were removed and the maxillary and mandibular residual ridges approximated as closely as possible. This position is referred to as the edentulous position of the temporomandibular joint (TMJ). Findings indicate that in the edentulous position the average size of the upper and posterior TMJ spaces and the distance from the center of the condyle to the center of the glenoid fossa on the Y axis of the TMJ are smaller than measurements in the intercuspal position. The size of the anterior space and the distance between the two centers on the X axis are larger in the endentulous position. Because vertical dimension is reduced in the endentulous position, the mentum is in a superior and protrusive position. The study indicates that when the maxillary and mandibular residual ridges are approximate there is a pathologic position of the TMJ and the mandible caused by the loss of all teeth. The study shows that the condyle has the potential to move backward and upward excessively. As a result of the study, the concept of the edentulous position of TMJ is introduced. This concept is important in determining the proper position of the condyle in the glenoid fossa and the correct vertical and horizontal jaw relationship of an edentulous patient when complete dentures are made.


Effects of intense chewing on some parameters of masticatory function. This study recorded the influence of 30 minutes of intense chewing on the masticatory function in 17 healthy subjects. Functional recordings of mandibular movements and velocity, measurements of masticatory efficiency, maximal occlusal force, and occlusal force endurance time were performed before and after functional stimulation and finally in a 2- to 5-day follow-up registration. After intense chewing, a substantially decreased masticatory cycle and occlusal level phase duration were recorded. No major mandibular displacements or changes in velocity were recorded. Masticatory efficiency and maximal occlusal force in the incisal region diminished after 30 minutes of intense chewing. Occlusal force endurance time was also lowered after intense chewing. The measurements were close to their original values at the follow-up. Intense chewing had various short-term effects on masticatory function, including a significant reduction of masticatory efficiency, maximal occlusal force, occlusal force endurance, and masticatory cycle duration.


Comparison of an anatomic versus physiologic method of posterior tooth placement for complete dentures. Many authorities agree that artificial teeth should occupy the same positions as their natural predecessors to minimize interference with muscle function. A survey revealed that 59.2% of dental schools taught students to arrange mandibular posterior teeth over the crest of the ridge. That method was compared with a physiologic method of tooth placement. Fifty subjects, 33 women and 17 men, participated in the study. Arranging the mandibular posterior teeth with the central groove over the crest of the ridge resulted in a mean reduction of 2.72 mm in arch width. In the female subjects, the mean reduction in arch width of 3.06 mm was 56% greater than the mean of 1.96 mm recorded for men.


Working cast verification.

Working cast verification. The procedure described can allow correlation of clinical recordings of the patient's centric position with articulated working casts, thereby potentially eliminating most of th occlusal adjustments required when the restoration is seated in the mouth.


The transverse strengths of three denture base resins reinforced with polyethylene fibers. This investigation compared the transverse strengths of three denture base resins with and without polyethylene reinforcement fibers. These fibers were incorporated in 10 specimens each of a high-impact strength resin, a rapid heat-polymerized resin, and a light-activated resin. Each specimen was broken on an Instron universal testing machine using a three-point load after processing and air drying. The values obtained were then compared with values previously recorded for the same type of specimens without incorporated fibers. Only the light-activated denture base resin specimens exhibited a significantly higher mean transverse strength after polyethylene fiber reinforcement.


Shear strength of laboratory-processed composite resins bonded to a silane-coated nickel-chromium-beryllium alloy. The shear bond strengths of three commercial laboratory curing composite resin veneers bonded to a nickel-chromium-beryllium alloy treated with the Silicoater system were evaluated. Two light-cured resins and one heat- and pressure-cured resin were evaluated. No statistically significant difference in bond strengths among the three resins was found. Microscopic analysis of the fracture surfaces indicated that all failures were complex and cohesive in nature within the resin and composite. On the basis of the shear bond strengths measured, any of the composite resin veneers tested appear to be clinically acceptable.


Management of implant malalignment precluding transfer coping placement. Two techniques have been described whereby an impressin can be made when malaligned osseointegrated implant abutments preclude the use of conventional transfer copings.


Marginal accuracy and geometry of cast titanium copings. The biocompatibility of titanium with human tissue is well established; its potential as an alternate metal for crown restorations has yet to be fully investigated. This study measured the geometry and accuracy of coping margins cast in Ti, 99.5% chemically pure. Twenty castings with 45-degree facial and 90-degree palatal margins were made by indirect technique with a commercial system using recommended procedures. They were then cemented with ZnPO4 cement. The coping and die assemblies were embedded in resin, sectioned longitudinally, and measured with a microscope at x50 power. Casting shrinkage was characteristic, particularly along the horizontal axis in the plane of the shoulder. Although horizontal linear shrinkage of 45-degree margins was greater than that for the 90-degree form, the surface of marginal discrepancy was greatest with the 90-degree configuration.


Adhesion of resin to casting alloys.

Adhesion of resin to casting alloys. The bond strength of a composite resin bonded to various dental casting alloys with three adhesive systems--Silicoater, Panavia, and Superbond C&B--was investigated. The metal surfaces were treated solely with aluminum oxide blasting before application of the adhesive. Thermal cycling caused a reduction in bond strength for all combinations of the adhesive systems and alloys, but the Silicoater system recorded the greatest bond strength. The 4-META system was equivalent to Panavia system in bond strengths to most metals and exhibited greater strength with others.


Thermal response to multiple use of a twist drill. The objective of the present investigation was to determine whether injurious thermal changes occur in the pulp chamber if a twist drill is used 10 times, and to find whether there is a correlation between temperature rise and distance between a drilled channel and the pulp chamber. Twenty caries-free, human, premolar teeth were randomly distributed to two dentists. With a new 2 mm twist drill, each dentist prepared 10 pinholes (one hole per tooth). Intrapulpal temperature change during the drilling procedure was recorded. The data were statistically analyzed by the Spearman rank order correlation coefficient. The results showed that twist drills should not be used for more than five pinholes (p less than 0.001). The distance between the pin channel and the pulp chamber does not influence heat generation in the pulp chamber.


A 3-year postoperative clinical evaluation of posts and cores beneath existing crowns. Fabrication of posts and cores for fixed partial denture (FPD) and removable partial denture (RPD) abutment restorations is common in dentistry. The biocompatibility of various post and core techniques with the restorations was clinically evaluated according to location and function. In this study, 154 post and core constructions for 150 patients were observed for a 3-year period to determine if the function of the original restorations remained unsatisfactory. The following techniques were included: (1) screw post and light-curing composite resins, (2) cemented post with parallel sides and light-curing composite resins, and (3) a cast and core technique. Seventeen of the 154 restorations failed; four failures were attributed to root fractures, three to radicular caries, and five to crown dislodgement, while five failures were from detachment of the post and core from the root. The statistical analysis revealed that only the factor "type of abutment" (RPDs and FPDs) had some effect on the failure of the restorations.


The dentin-root complex: anatomic and biologic considerations in restoring endodontically treated teeth. The restoration of endodontically treated teeth has been the focus of considerable controversy and empiricism. Time-tested methods have been highly successful in some respects, but failures are still apparent. The inherent causes of failure are rarely evaluated and the limitations of specific restorative systems are seldom identified. Regardless of the system, there should be a thorough understanding of the anatomy and biology of the dentin and root supporting the restoration on the part of the practitioner, because both endodontic and restorative procedures alter the hard tissues.


Anterior mandibular subapical osteotomy: a useful treatment for patients with severely worn mandibular anterior teeth. Rehabilitation of patients with severe dental wear is a complex diagnostic and restorative problem. As wear occurs, space for restorative materials is lost, and unique treatment techniques are needed to provide good esthetics and function. Use of orthognathic surgery to reposition mandibular anterior teeth and supporting alveolar bone can create a more ideal environment for restorative procedures.


The effect of slot preparation length on the transverse strength of slot-retained restorations. An in vitro study was conducted (1) to compare fracture strength of amalgam restorations retained with retentive slots of different lengths when stressed with a transverse force, (2) to determine if beveling the slot preparation resulted in an increase in fracture resistance to a transverse force, and (3) to evaluate the incidence of unrestorable tooth fracture as it relates to slot preparation length. Six groups of 10 specimens were prepared with slots of increasing length, with each specimen receiving four slots of equal length. Slot preparations in group 6 were beveled. Results showed that shorter slot preparations provided statistically equal amounts of resistance to a transverse force as did the longer preparations. Beveling the slot preparation did not significantly increase fracture strength. Specimens restored with longer slot preparations failed unrestorably more often than restorations retained with shorter slot preparations.


Seating and retention of complete crowns with a new adhesive resin cement. The retentive property of cast gold complete crowns cemented with an adhesive resin cement (Panavia Ex) was compared with retention of crowns cemented with zinc phosphate cement (Flecks) and the conventional resin cement (Comspan). The effect of these agents on seating of crowns also was evaluated. Panavia cement exhibited the highest retentive strength, with values almost twice those obtained with zinc phosphate cement. However, the difference in mean retention values of crowns cemented with Comspan cement or with zinc phosphate cement was not statistically significant. Both resin cements used in this study provided better seating of crowns than did zinc phosphate cement.


The cantilever fixed partial denture--a literature review. The cantilever fixed partial denture (FPD) is a restoration with one or more abutments at one end and unsupported at the other end. Forces transmitted through the cantilevered pontics can cause tilting and rotational movements of the abutments. In a cross-arch unilateral cantilever FPD, the distal cantilevered unit is subjected to comparatively less force than the contralateral posterior abutment. The unilateral lack of terminal abutments causes lateral bending forces activate peripheral inhibitory feedback reactions from the periodontal and/or temporomandibular mechanoreceptors. The greatest strain in distal cantilevered FPDs is recorded mesial to the most distal retainer because most fractures occur in this location. To improve the prognosis of the FPD cantilever, the number of abutments should be increased and the number of pontics decreased. The abutment teeth need long roots and acceptable alveolar support. Prepared abutments require adequate length and parallel axial walls. An equilibrated and harmonious occlusion is necessary, as well as exemplary oral hygiene. A cantilevered FPD with adequate periodontal support can replace any tooth in the dental arch, but is especially useful as an alternative to a removable partial denture. The cantilevered FPD requires at least two abutment teeth. The only documented exception permitting a single abutment is the replacement of a maxillary lateral incisor with the canine as an abutment. An alternative to the cantilevered FPD is the osseointegrated implant. As osseointegrated implants become more popular, the need for the tooth-supported cantilevered FPD may decline, but it will remain an alternative treatment modality.


An impression technique to make a new master cast for an existing removable partial denture. When the master cast for a removable partial denture is lost and a well-fitting framework remains, it may be necessary to replace the master cast. A two-step impression procedure is described that combines the altered-cast technique and the use of a modified disposable tray. Finger pressure is maintained on the major connector throughout the making of both impressions, to prevent framework movement and loss of contact with prepared rest seats.


Reliability of a facebow transfer procedure. The three-dimensional orientation of a maxillary cast mounting from a simulated-kinematic facebow transfer was evaluated in multiple trials among three operators on a single subject. The anterior and posterior anatomic facial reference points were marked on the subject. Each operator performed a separate series of trials to reset the anterior facebow component, the two posterior facebow components, and a control series with no resetting of any facebow components relative to the subject. The x, y, and z coordinates of three reference points on the maxillary cast were determined with a machinist microscope relative to a fixed reference after each facebow transfer. A range of differences between mountings of the maxillary cast were found between trials with all three methods used. These mounting errors were due to setting of the instrument and would be expected in routine clinical use of this instrument.


Determining the occlusal plane with the Camper's plane indicator. Camper's line has been used by many dentists as a reference in determining the plane of occlusion in edentulous patients. This article describes an instrument that provides the dentist with a clear and accurate assessment of the occlusal plane in relation to Camper's line.


Racial norms: esthetic and prosthodontic implications. A review of the orthodontic literature reveals that different races have different cephalometric norms. This has great implications in the placement and arrangement of teeth and in the evaluation of esthetics in people of dissimilar ethnic origins. In the diverse American society, prosthodontists and restorative dentists need to be concerned with the phylogenetic characteristics of their patients. The resultant esthetic differences can have significant importance in the function and design of prostheses.


The UCLA abutment: a four-year review.

The UCLA abutment: a four-year review. The UCLA abutment has been used over the past 4 years in the restoration of osseointegrated implants. The design of the abutment allows fabrication of the restoration directly to the implant fixture, bypassing the transmucosal abutment cylinder. This technique is valuable in overcoming problems of limited interocclusal distance, interproximal distance, implant angulation, and soft tissue response. Another major advantage with the UCLA abutment is that of improved esthetics. After treatment of 46 patients with 118 UCLA abutments, the 4-year success rates are 95.8%.


Silicone nasal radiation carriers.

Silicone nasal radiation carriers. A technique for fabrication of a flexible shielded afterloaded silicone nasal radiation carrier is described. The technique uses a rubber base impression of the nasal cavity from which a silicone radiation carrier is made. Plastic tubes for afterloading of the radioactive sources and a lead shield were incorporated into the carrier. The carrier permitted accurate location of the radioactive sources in the nasal cavity and reduced the radiation exposure.


Occlusal adjustment as treatment for tenderness in the muscles of mastication in category 1 patients. When a lateral pterygoid muscle is more tender to palpation than the other muscles of mastication, and a stress test is positive, an occlusal cause should be suspected. Patients with lateral pterygoid tenderness are divided into three categories according to two criteria: the position of the condyles in their glenoid fossae and the degree of dysfunction in the articulation. Only patients in category 1, those with a centered condylar position and without dysfunction, are discussed in this article. Occlusal adjustment is executed on the basis of information gathered from radiographs of the temporomandibular joint, diagnostic casts, and leaf gauge measurements of unequal bilateral occlusal contact. The amount of tooth structure requiring removal can be determined by using leaf gauges of differing thicknesses. Occlusal adjustments are performed without mandibular manipulation until the tenderness of the lateral pterygoid muscle is relieved.


Passive eruption in the treatment of craniomandibular dysfunction: a posttreatment study of 151 patients. There is sparse posttreatment evaluation of craniomandibular dysfunction (CMD). This study describes the use of an orthopedic interocclusal appliance with passive eruption for the treatment of CMD. The clinical results of 151 patients treated using the passive eruption procedures were assessed at a follow-up time averaging 1.75 years after treatment with a highly structured telephone interview questionnaire. The treated patient population was chronic, averaging 2.58 years in pain and 2.25 previously ineffective treatments for their CMD. Although this was a subjective inquiry, the treated patients confirmed significant reductions in symptoms, a decrease in pain and interference ratings, and reduced health care utilization. A subgroup of 38 patients who previously had no relief with flat-plane therapy exhibited similar positive results. Treatment failures were also assessed but were low. The results are discussed in terms of the patients' support of the efficacy of the passive eruption procedure, including the need for future research.


Microbial contamination in two antimicrobial and four control brands of alginate impression material. Previous investigations have revealed commercial alginate impression material to be contaminated with viable microorganisms. Some manufacturers are now producing alginate materials that contain antimicrobial agents. The purpose of this study was to test and compare two antimicrobial and four control brands without antimicrobial agents of commercial dental alginate impression material for the presence of viable microorganisms. Forty-eight or 96 measured samples of each brand were taken from previously unopened containers using a sterile technique. The samples were placed on chocolate agar plates and in thioglycolate broth tubes and were incubated along with appropriate parallel controls. After incubation, colonies were enumerated, gram-stained, and identified using standard microbiologic methods. The two antimicrobial brands contained viable organisms in 12.5% of the samples incubated on agar media and also contained such organisms from 0% to 16.7% of the samples incubated in thioglycolate media. The four control brands contained viable organisms in from 29.2% to 100% of the samples incubated on agar media and also contained these organisms in from 25% to 79.2% of the samples incubated in thioglycolate media. There was a statistically significant difference (p less than 0.05) in contamination frequencies among some brands. Contamination frequencies of the top and middle portions of the containers did not differ significantly. The concentration of organisms in contaminated samples was 2.8 colony-formed units (CFUs) per gram for the antimicrobial alginates, and from 9 to 161.1 CFUs per gram for the control brands.(ABSTRACT TRUNCATED AT 250 WORDS)


The bond strength of elastomer tray adhesives to thermoplastic and acrylic resin tray materials. This study evaluated the bond strength of selected impression materials (Permlastic, Express, and Hydrosil) to a thermoplastic custom tray material as a function of drying time of the adhesive after application to a tray material. In addition, bond strengths of a polysulfide impression material to an acrylic resin tray material and to a thermoplastic tray material made directly against wax were evaluated. Bond strengths were obtained directly from values of applied load at failure and important conclusions were drawn.


Electromyographic activity of the jaw-closing muscles in patients with osseointegrated implant fixed partial dentures. The control of postural and synergistic jaw reflexes involves interrelated sensory input from receptors in the jaw muscles, temporomandibular joint, periodontal ligament, and mucosa. This investigation was done to determine whether a decrease in intraoral sensory afferent discharge significantly altered the onset of the jaw-unloading reflex. The subject population consisted of three groups with 10 subjects in each group. Group 1 had maxillary and mandibular natural teeth and group 2 consisted of edentulous subjects with complete dentures. Group 3 consisted of edentulous subjects with maxillary complete dentures and mandibular complete implant-supported prostheses. The unloading reflex was initiated with a muscle-unloading device and recorded with a storage oscilloscope. A one-way analysis of variance found no significant differences in the unloading-reflex latency for the masseter or temporal muscles among the three experimental groups (p less than 0.05).


Applying business principles to a prosthodontic practice. Determining the optimum fee for prosthodontic services is difficult. Most methods of determining fees are based on comparisons with other practitioners or with established fee schedules. However, comparisons alone are inadequate because they ignore the practitioner's underlying costs. Since it costs each individual practitioner different amounts to produce dentistry, dental fees should be highly individualized. This article presents a model for evaluating fees for prosthodontic services based on both underlying costs and intangible variables such as the dentist's skill, experience, and quality of care.


Evaluation of heat-cured resin bases following the addition of denture teeth using a second heat cure. This study compared heat-cured acrylic resin denture baseplate distortions following a second heat cure used to add the denture teeth. The second heat cure was done with three different water-bath curing temperatures. The distortions were evaluated in three planes by use of a measuring microscope. Recorded distortions were not clinically significant.


Equipping a dental laboratory: making a shell blaster. A shell blaster has many uses in a dental laboratory. However, because of the size and expense of this piece of equipment, it is not often found in many office laboratories. This article describes a method for making a relatively small, fully functional shell blaster for less than one hundred dollars. The shell blaster can be changed into a sandblaster by removing the walnut shells and refilling it with 26-grit aluminous oxide.


Removable prosthodontic laboratory survey. This article presents a brief review of the literature concerning the curriculum deemphasis for removable prosthodontics, especially on the subject of complete dentures. The authors surveyed commercial dental laboratories specializing in removable dental prosthetics in three major Texas cities to determine whether dentists were submitting adequate records and information with their complete denture work authorizations. Results indicate that dentists are requesting services from their laboratories without providing adequate records.


A simplified matrix for making direct cores. This article describes the use of a pharmaceutical gelatin capsule as a matrix for making various posted and nonposted crown substructures. The procedure used for a cast post and core using this matrix is outlined.


Making an alternative occlusal splint.

Making an alternative occlusal splint. An occlusal splint is commonly used in the diagnosis and management of temporomandibular disorders. In a partially edentulous patient a poorly adapted removable partial denture can prevent the use of a conventional occlusal splint. This article describes the fabrication of an occlusal splint that also incorporates a provisional removable partial denture.


Eliminating coronal discoloration when cementing all-ceramic restorations over metal posts and cores. Opaque procelain was fused over metal posts and cores. This procedure permitted the definitive all-ceramic restorations to possess a more uniform shade between teeth restored with metal posts and cores and adjacent vital teeth.


Kleptomania: a review of the research.

Kleptomania: a review of the research. Research on kleptomania is limited. Earlier views and recent reports of treatment are reviewed in this article. More study is needed to delineate this impulse-control disorder.


Intensity of midlife crisis on responses to the Death Concern Scale. The relationships that exist between the intensity of midlife crisis and individual items on Dickstein's (1972) Death Concern Scale were explored. The question of whether the intensity of a crisis could be used to predict responses to items on the scale was also investigated. A group of 235 person, 30-60 years of age, completed the scale. Pearson product-moment correlation coefficients indicated relationships for 7 of the 30 items on the scale. Using forced-entry regression, with intensity of crisis as the independent variable and the items on the scale as dependent variables, I found 8 scale items with reportable beta scores of .10 or above. The relationships and predictors reflected cognitive and emotional aspects of death.


Degree of asymmetry in lateral preferences: eye, foot, ear. Lateral asymmetry in eye, foot, and ear preference was measured using a 15-item questionnaire administered to 442 subjects. Degree and magnitude of asymmetry were greatest for eye, followed by foot and ear. Intercorrelations of lateral preferences were all positive and significant. Two primary factors, eyedness and earedness, were established.


A study of the comparative structure of guilt and shame in a Chinese society. On the basis of previous theoretical and empirical analyses of the comparative structures of guilt and shame, the authors hypothesized that antecedent condition (personal inadequacy vs. moral norm violation), audience presence, and personal responsibility attribution would distinguish shame from guilt. Although the subject population was Hong Kong Chinese, evidence from previous studies suggests that the comparative structures of guilt and shame are quite similar across cultures. The subjects were asked to recall either a guilt or a shame incident, and their responses were then coded into the predictor variables. The results of the study indicated that guilt was most likely to emerge when individuals had violated a moral norm and held themselves responsible for their conduct. In contrast, shame emerged more frequently when subjects felt personally inadequate than when they had violated moral norms. Moreover, when a guilt incident was reported, and audience was rarely mentioned, whereas subjects who reported a shame incident would generally feel personally responsible and often mentioned being looked at or evaluated. However, neither personal responsibility nor the presence of an audience seemed to be essential for a person to experience shame.


Opponent colour coding is a universal strategy to evaluate the photoreceptor inputs in Hymenoptera. Behavioural tests were carried out with 9 hymenopteran insect species, which ranked certain sets of coloured stimuli according to their subjective similarity to a previously memorized stimulus. Kendall's tau co-efficient is employed for the analysis of correlation between these similarity rankings and the colour distance rankings predicted by various models of neural colour computation. The models are based on the measured spectral sensitivities of photoreceptor colour types and use a variety of simple colour coding systems to derive hypothetical colour distances. The correlation between the predictions of the models and the behavioural results serves as a measure for the likelihood of existence of a colour coding system. In all species, the similarity rankings can be best explained by assuming that colour is coded on a perceptual level by two colour opponent mechanisms. Brightness differences are ignored, indicating that an intensity-coding sub-system is not used in colour discrimination by the insects investigated. The weighting factors of the colour opponent mechanisms differ between species in detail, but not in the principles involved. It is thus possible to employ a standard measure of perceptual colour distance (colour hexagon distance) to predict the capacities of colour discrimination adequately in all the tested insects.


Correlates of a residential pesticide contamination in a self-selected sample. We evaluated the behavioral, health perception, and physical health correlates of a residential pesticide misapplication on 54 individuals and identified factors differentially related to various levels of distress. Study participants were mainly concerned with health issues and exhibited somatic symptoms. Behavioral actions designed to obtain information regarding exposure levels and to reduce exposure were adopted. We found that factors such as a higher contamination level, involvement in a lawsuit, and belonging to a consumer action group, were strongly related to higher levels of psychological distress and, to a lesser extent, to behaviors, somatic symptoms, and health perceptions.


The refractive development of the eye of the American kestrel (Falco sparverius): a new avian model. Most measures of avian visual performance are carried out on commonly available domestic species such as the chicken, and most of the data on avian induced refractive error deals with chickens. Raptors are predatory birds in which good visual resolving ability is particularly important. Behavioral studies indicate that the eyes of raptors have two to three times the resolving ability of the human eye. The domestic chicken is precocial at hatching whereas most raptors are semi-altricial. This study was an effort to determine if the effect of early visual deprivation on the refractive development of the chicken eye can be reproduced in the American kestrel, a species which is not domesticated and in which the need for acute vision is particularly important. Visual deprivation was achieved by unilaterally applying translucent plastic goggles over the eyes of kestrels two days after hatching. Refractive error was measured using a retinoscope and trial lenses. Ocular growth was monitored by A-scan ultrasonography, and frozen ocular sections of sacrificed birds. The effect of the experimental manipulation on the contralateral control eye and body weight was evaluated each day over a 42-day period. The goggles did not significantly affect the normal changes in body weight or the normal pattern of ocular growth and refractive development in the untreated eyes. An analysis of the refractive state changes as a result of form deprivation was made each week for 6 weeks after hatching on both the treated and untreated eyes in a separate group of experimental birds. Visual form deprivation caused a significant myopic shift in refractive error and a significant increase in the vitreous chamber depth in the treated eyes at 3 and 6 weeks of age. However, the amount of myopia produced is much less than that induced in chicks, and in certain cases hyperopia is produced. The kestrels recover from myopia and hyperopia within 10 days of goggle removal, after 3 to 4 weeks of deprivation. This study is the first indication that chickens may not be a representative bird model for studying form-deprivation myopia. First, myopia is not always produced in kestrels in response to form deprivation. Second, kestrels are severely myopic at hatching and therefore, the direction of emmetropization is opposite to that found in hatchling chicks.


Directionality of phase locking in auditory nerve fibers of the leopard frog Rana pipiens pipiens. A dorsal approach to the eighth nerve and free-field stimulation were used to investigate the effect of sound direction and intensity on phase locking in auditory nerve fibers of the leopard frog Rana pipiens pipiens. Tuning curves of 75 auditory neurons were analyzed (Fig. 2). Amphibian papillar neurons, but not basilar papillar neurons, exhibit significant phase locking to short tone bursts at the characteristic frequency (CF), the degree of phase locking (vector strength) decreasing with the neuron's CF (Figs. 3, 4 and 10E). Vector strength increases with sound pressure level to saturate about 20 dB above threshold, while the preferred firing phase is only slightly affected (Figs. 5 and 6). In contrast, sound direction hardly affects vector strength (Figs. 7, 8, 9A and 10A and C), but has a strong influence on the preferred firing phase (Figs. 7, 8, 9B and C, 10B and D): With respect to anterior tone presentation there are phase lags for ipsilateral and phase leads for posterior and contralateral presentation. Phase differences between both ears show a sinusoidal or cardioid/ovoidal directional characteristic; maximum differences are found with antero-lateral tone presentation (Fig. 11). The directionality of phase locking decreases with the neuron's CF (Fig. 10F) and only slightly changes with sound pressure level (Fig. 12). Thus, phase locking of amphibian papilla neurons can potentially provide intensity-independent information for sound localization.


Enhancement of sensitivity in photoreceptors of the honey been drone by light and by Ca2+. Deeply dark adapted (1 h) photoreceptor cells of the honey bee drone show a light-induced enhancement of sensitivity (facilitation) as an aftereffect of illumination or in the presence of dim backgrounds. The Ca(2+)-dependency of this effect was studied: Reduction of extracellular Ca2+ to 0.1 mM decreases the sensitivity of a dark adapted cell, and the light-induced increase in sensitivity due to repetitive, dim, 20 ms test flashes is slower than in normal saline. After a sensitizing conditioning light, the sensitivity drops faster in low-calcium saline. The light-induced enhancement of sensitivity is mimicked by pressure injections of low amounts of Ca2+ (Ca2+/EGTA-buffers; 0.15 microM free Ca2+) into a dark adapted cell. Injection of EGTA alone decreases the sensitivity. Injection of a solution containing ca1 mM free Ca2+ sequentially decreases and later increases the sensitivity transiently. These results suggest a model in which a progressive increase in intracellular Ca2+ concentration by light first increases (facilitates), and, at higher concentrations, decreases (light adapts) the sensitivity of the cells. One possible site of action for this positive and negative feedback control of cell sensitivity by Ca2+ is the endoplasmic reticulum.