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Sequential Supernumerary Teeth Development in a Non-Syndromic Patient; Report of a Rare Case

Isolated impacted supernumerary teeth are quite rare, but they can be seen associated with several syndromes such as cleidocranial dysostosis or Gardner’s syndrome. This article aims to discuss a case of sequential formation of supernumerary teeth with no other associated disease or syndrome. A 17-year-old Iranian male with 8 impacted supernumerary teeth was referred to the department of pediatric dental clinic at Shahid Beheshti Medical University in Tehran with a history of several impacted unerupted teeth. Repeated and periodical clinical and radiographic examinations revealed newly formed teeth buds in unusual dental ages. All extra teeth were associated with generalized enamel hypoplasia to some degree on their relative permanent adjacent teeth. The patient did not have any record of a systemic disease or any syndromic condition to relate his dental problem to. This rare condition involved repeated and continued formation of extra teeth out of the normal numbers and dental age evident in serial radiographs.


INTRODUCTION
Supernumerary teeth (ST) are defined as an extra set of teeth that are counted more than normal count in the component of primary and/or permanent dentition [1] To date several different theories have suggested varying etiologies; factors including: 1. abnormality or hyperactivity of the dental lamina, [2] reactivation of the remaining epithelium after break up in the tooth band (dichotomy theory) [3], and 3. The process of atavism, the return to or appearance of an ancestral condition or type [4]. In addition, familial tendency and racial influences should also be noted when looking at the cause [5]. The formation of multiple supernumerary teeth (MST) does not follow the normal path in Mandelian pattern [6].
The anterior maxillary region appears to be the most usual site of occurrence with mesiodense being the most common ST located at and around the palatal midline [7]. The prevalence of ST is reported between 0.3% and 3.8% in America with the male population being affected twice as frequently as the female group [1]. ST may occur in single or multiple patterns, unilateral or bilateral. Multiple ST is counted for 14% of all ST cases, [1] while it is rarely found in individuals with no other associated syndrome [8]. The most known syndrome associated with ST is cleidocranial dysplasia. There are several other syndromes with a lower frequency of association with ST including: Apert syndrome, Gardner syndrome, Down syndrome and Crouzon disease (Table 1 and 2). The size and shape of ST is different, but in certain cases it is close to the normal adjacent teeth, the so-called supplemental teeth. They may be as variable as those with tuberculates (more than one cusp or tubercle) or even conical (peg in shape) [9]. Several methods have been introduced to classify these extra teeth: 1. Non-sequential in which all ST are developed in a short period of time with no further formation of any tooth bud after a certain age [2]. Sequential where tooth formation will continue for a longer period with newly formed tooth buds appearing in a later stage of life [10,[11][12][13][14]. MST has a direct influence on the treatment protocol and its outcome [15].
The purpose of this article was to report a rare case of sequential MST in a non-syndromic Iranian patient.

CASE REPORT
A 16-year-old male patient was referred to the pediatric dental clinic at Shahid Beheshti Medical University, Tehran in fall 2008 with failure of eruption of several upper and lower permanent teeth (Fig 1). The patient was the second child in his family with no trace and history of any similar condition in other family members. Medical and laboratory test histories revealed no specific medical condition with an overall normal health. The level of intelligence and mental development was assessed as normal based on Wechsler criteria. Physical examination revealed a thin body, slight hyperlaxity in the finger joints raising the possibility of joint problem, later ruled out by a full orthopedic evaluation. Results of a general laboratory test including the thyroid gland function revealed no problem. The present teeth were as follows in the first visit: Enamel hypoplasia was noted in most of the erupted teeth. Severe caries was noted especially in retained primary teeth. The 1st upper left and1st lower right permanent molar teeth were absent as extracted earlier due to severe caries (Fig 2). Radiographic evaluation of the chest and wrist showed no sign of abnormality. Panoramic views (three year apart) were also available for evaluation of the patient's development progress ( Figure 3, 4 and 5). The first radiograph was taken when he was 11 years old, at which three supernumerary teeth were located at the upper anterior and right premolar regions namely (Fig 3).
The second panoramic radiograph was taken at 14 years of age showing four other supernumerary teeth bilaterally in the mandibular premolar and left maxillary premolar areas as indicated below: Interestingly, no signal of any of these teeth could be traced in earlier radiographs. The patient's history revealed that the right and left upper 6 was extracted due to severe caries (Fig 4). New supernumerary teeth were observed in the third radiograph taken at 17 years of age that did not have any trace at earlier radiographs. The locations of these extra teeth were defined between 1 and 1'. This newly appeared tooth was named as 1". The upper left maxillary central incisor was present at the time of oral examination while the right central and both upper lateral insisors remained unerupted.
In addition, the lower left lateral incisor was also present in the oral cavity (Fig 5). There was a total number of 8 extra teeth in the jaw. The collective figure of these extra teeth are shown as: Consultations were sought from oral surgery and orthodontic departments in order to plan the best treatment option for the patient. An overall agreement was achieved to remove all the malformed and malposed teeth including: several unsavable permanent teeth as listed below: The treatment process included a phase of multiple extractions under general anesthesia as several surgical sites needed intervention. This was later followed by an initial step of orthodontic forced tooth movement in order to encourage the eruption of impacted teeth including: The patient was discharged the day after the operation with his orthodontic visits set along with a full mouth follow up at 6 and 12 months. The patient's current status is as close to normal with an appropriately aligned set of teeth in order as shown in Fig 6.

DISCUSSION
Supernumerary teeth are usually seen along with and at the same time as the normal teeth. They can also be seen associated with certain syndromes.
The rate of multiple supernumerary teeth has been reported as 23% among all supernumerary cases [4,16]. An important point is that the development of 5 supernumerary teeth of this report was noticeable over a 5-year period (sequential supernumerary teeth formation. Multiple nonsequential, non-syndromic supernumerary teeth tend to occur more in the mandibular premolar area, as recently reported [17][18][19][20][21]. (Table 3).
Both premaxillary and mandibular premolar regions were equally affected in the current case, followed by maxillary premolar region with a lower incidence (less affected teeth). Gomes et al. (2008) reported three cases of sequential supernumerary teeth in mandibular premolar and premaxillary regions considered as the most frequent areas for these teeth to be detected respectably. The maxillary premolar region was, however, the site least affected. Supernumerary teeth of the current case were more frequent in themaxilla (five in the maxilla and 3 in the mandible) as seen in other reports [9]. Non-syndromic multiple supernumerary teeth are more likely to occur in patients whose other relatives are also Continuous supernumerary teeth formations are thought to be due in part to reactivation of the tooth follicle with no clear explanation. Another possible mechanism is unresorbed remained dental lamina. This could lead to reactivation of the normal permanent teeth at the time of crown completion. Lastly it is thought that the crypts of the supernumerary teeth may have been present but were not detectable on earlier radiographs [2]. The Wnt gene has been considered another likely etiology for supernumerary teeth [22].