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Slavicek * The Masticatory Organ

Sadao Sato:

The dynamic functional

anatomy of the
craniofacial complex and
its relation to the
articulations of dentition


Evoluciona! Aspects of Craníofacial Bones
Craniofacial Bone Connection
Sphenoid Bone
Occipital Bone
Vomer Bone
Temporal Bone Craniolacial Bone Dynamics Occiput-Spheno-Maxillary Complex
incfuding the Vomer in relation to
the growth of the maxillary complex Temporomandibular System The Importance of Occlusal Function
on che Mandibular Growth Craniofacial Growth and Developmenc with
Special Attention to the Occlusal Plañe Implicación of Dental Practice
Every bone that constitutes the modern human skull formed an esscntial framework for adapting the brain and
sensory organs. Craniofacial mandibular structures, bcing a functioning system, are regarded as the most
complicated system ín the human body (Fig. 1). They consist of 28 bones: six ossicular bones (malleus, incus
and stapes), eighr vault bones (occipital, parietal, temporal, frontal and sphenoids) and fourteen facial bones
(maxiila, nasal, lacrimal, ethmoid, concha, vomer, mandible, malar and zygoma).
The craniofacial bones are joined together at their junctions by so-called sututes orsynchondroses. le is important
to understand that, owing to these attachments, the bones are situated within a flexible or moving structure when
pressure or tensión is exerted on ctaniofacial mandibular structures. The sutures resist gross separation of the
component bones, but also permit slight relative movement. However, in the past anatomists regarded cranial
sutures as immovable joints, belíeving that each bone is rigidly positioned and that the bones are rel-atively fixed
to each other, although the movement of skull bones is mainly due to brain growth, mus-ele contraction and
functions of the masticatory


organ. Retzlaff'' '' and Frymann a * reported that crania! bones exhibíted a state of motion. Frymannís' study
using fixed transducers witli the head stabilized in a fixed position revealcd that cra-nial motion is an
independen: one, affected by the individuáis breathing cycles.
To understand the dynamics of the craniofacial complex, it is of utmost importante that we ilrst discuss its
functional anatomy (S m. The cranium is tomposed of the upper and mid facial skeieton. The calvarium surrounds
the superior and lateral por-tions of the brain and the bones of the cranial base lie beneath the brain. Sometimes
all bones sur-rouncling the brain are collectively referred to as the neurocranium, as they originated from the
meninx primitiva thac surrounds the rostal portion of the neural tube. The midfacial skeletal trame is a fur-ther
part, known as the visceral cranium. However, the cranium and the facial bones are not sepárate functional units.
The size of the cranium at birth is approximately 60 to 65% its final size and it grows rapidly. By the age of five
years the cranium has developed to approximately 90% ¡ts final size; this growth is achieved by sequentiaJ
remodeling of the morphology of each región. External forces applied to these forming structures have the
potential to distort shape and growth, wich grave consequence for the final form and functions.
The floor of the brain case or cranial base was described as a foundation or scaffblding for the face. The facial
complex may also be regarded as a superstructura,
The maxilla is a unique structure in its own way. Aside from one extensión or process that directly braces the
maxilla against the cranial bone, like the maxillo-frontal process, no other contacr exists between the maxilla and
the skull base. It is there-fore braced against other bones as floating buttres-ses"l).
The facial bones also support various organs enclosed in its cavities such as the oral, nasal, orbital,
nasopharyngeal sinuses, which include the organs of sight, breathing, smelling, eating, spea-king and hearing.
Functions of che facial skeieton thac involve denti-tion are mascication, deglutition, speech, respira-tion, facial
expression, and posture as well as stress management. Functional movements of the mandible, chewing,
swallowing, speaking and bruxing behavior, are now regarded as the most

To understand the dynamics of the craniofacial complex, it is of utmost importance thac we first discuss its
functional anatomy
The functions of facial skeieton, which involves the dentición, are masticación, deglutition, speech, respiración,
facial expression, and posture as well as stress management.

R. Slavicek • The Masticatory Organ

effective and important functions of the craniofacial

striictnrc. As homeostasis and the stability of occlu-sion
involve other systeras as well, the dentist is confronced
with problems of equilibration of the teeth, whereby the
problems might origínate from factors quite remote from

Evolutionary Aspects of
Craniofacial Bones

The base of the skulJ that part whicli con-nects the skull vault and the facial skull changed dramatically during
the processes of human evohition.

Therefore, in ontogénesis of modern human, the viscerocranium especially the maxillary complex mainly grows
in downward direction.
The base of the skull, the part that connects the skull vault and the facial skull, changed dramatically during
human evolution. Comparison of a modern human skull with that of a modern ape reveáis same striking
differences "*' (Fig. 2). The human neurocranium with its vertical forehead, bulbous occipur, rounded cranial
vault, and centrally locar-ed foramen magnum appears to constitute the upright postute of the skull, although the
viscerocranium in humans seems to be signifícantly small-er and wider than that in apes. The inferior projec-tion
of the mastoid process in human beings is rela-ted in part to che flexure of the cranial base. The geometry and
mechanics of the ctanial base flexure are determined by the spheno-occipital región of the cranial base.
The anteroposterior dimensión of the human viscerocranium is strikingly smaí!, especially if the rela-tive size of
the neurocranium is taken into account. When viewed in profile, one observes retrog-nathssm of the mid and
lower face to fíat appear-ance with more vertically inclined iong face than that in apes. When a monkey skull is
viewed from below, the projection of the maxillary región is fiar forward, with a longer anteroposterior dimensión
of the spheno-occipital connection of the cranial base. A feature that determines the skull base in humans is the
flexure of the cranial base, which is measured by ascertaining the flexión angle (cranial angle) (Fig. 3). In
comparison to the skull of the quadruped, the skull base angle in humans is rela-tively small (Fig. 4). This is
believed to be mainly due to upright posture, the increase in brain vo-lume, and frontal positioning of the eyes - a
conse-quence of stereoscopic visión. Postnatal changes in the proportion of the human cranium also result in a
smaller basal flexión angle. Therefore, in the ontogénesis of the modern human being, the viscerocranium and
especially the maxillary complex mainly grow in downward direction (Fig. 5).

Sadao Sato

Based on these considerations, the vertical growth

of the viscerocranium in modern humans creates
some difficulty in terms of proper fitting of the
upper and lower dentition, because the descending
spatial position of the maxillary occlusal plañe
easi-ly creates anterior opening of the upper and
lower jaws without continuous mandibular
adaptation by rotation (Fig. 6). Thercfore,
functional adaptation of the mandible to maxillary
occlusal surfaces ehat continuously descend in
vertical position ís fundamental in otder to achieve
proper functional occlu-
sion. The anterior mimic muscles help to cióse the Anterior mimic muscles help to cióse the anterior
opening of the jaws, which prevencs the anterior openiag ofthe jaws which prevenís
development of anterior open bite maloccíusion , , , r
,j. i, ,, , 131 the development oi anterior open blte maloc-

Craniofacial Bone Connection

The bones constituting the craniofacial complex are

in a dynamic state of functional motion during life
ÍM), Cranial bones mainly consist of two parts
(Fig. 7 and 8):
Central connection of bones: ethmoid, sphenoicl,
occiput, vomer, maxillary bones
Bilateral connection of bones: temporal bones,
Lets us first consider the different parts or
srructures that interconnect with each other to form
craniofacial structures.
Sphenoid Bone
The sphenoid bone comes from the word ispheni
meaning wedge, as it forms a wedge between the As they are wedge between the face face and the brain. The
sphenoid bone plays a vital anc[ the b,-role in craniofacial morphology. It is joined by the occipital, ethmoid and
frontal bone, and is consi-dered to be an essencial element of the mid-sagittal cranial base. The sphenoid bone is a
principal central bone of the skull that is formed by cartilage. It provides early protection of capsular attachments
for vital organs and also plays a role in the early development of the skull, both phylogenetically and
It is also a major superstrticture for the attachments of masticatory
muscles, principally the temporalis on the greacer wings, the
superior belly ofthe extet-nal pterygoid in the horizontal portion oi"
the greater wing (wherein both pterygoids arise from

R. Slavicek * The Masticatory Organ

the latera] pterygoid plates) as well as che tensor palatal

muscles originating in che scaphoid fossa and
extending downward, crossing the hook of the
hamulus. In addition, che sphenoid bone serves as a
buccressed área for che temporal bone, as it is nec-
essary to rcsisc che pulí of the external pterygoid
muscles during function of the temporomandibular
joint""(Fig. 9).

It is separated froiii the sphenoid body by a synchondroses known as the spheno-occipital synchondroses.

The synchondrosis between the basilar porción of the occipital bone and the sphenoid bone is considered to be the
greatest joint in the skull.
Occipital Bone
The occipital bone is slighcly funnel-shaped, with a largc- opening known as the foramen magnum. The basilar
process is triangular in shape and is distin-guished by an oucer cortex and by inner cancellous bone. Ic is
hollowed ouc in adults by the sphenoidal sinus. In youngsters, up co puberty, ic is separated from the sphenoid
body by a synchondrosis known as the spheno-occipital synchondrosis.
The synchondrosis becween che basilar porción of the occipical bone and the sphenoid bone is considered ro be
che largest joinr in che skull. Ic is made up of thick fibrous cartilage, which serves as a shock absorber,
permicting growth, and simultaneously providing motional adjnstment againsr external stress.
In great apes, the cranial base is less flexed in the sagitcal plañe.
Vomer Bone
The vomer bone consises of two small flanges of bone chat conform with tbe underside of the body of the
sphenoid. It is ¡mportant because of the nasal septum and its attachments to che palatine and maxillary bones.
Aside from serving as a buctress for the upper jaw to receive shear forces, ir is an impor-tant site of downward
growth of the human face (Fig. 10).
In great apes, the cranial base is less flexed in the sagittal plañe, and the base of the vomer is posi-tioned further
anterioríy. The vomer plays an imporcant role as a transmitter of dynamic forces from the cranial base ro the
maxillary complex.

Temporal Bone
In the dynamic mechanism of the craniofacial skele-ton, the temporal bone is the most importanr one because of
its anatomical posición. The temporal bones are located in the lateral-most aspect of the skull and fie in the space
between the occipital, parietal and sphenoid bones (Fig. 11). The temporal bone's squamosal suture is fan-
shaped and flaps

over the parietal bone at its junction with the squa-ma (Fig. 12).
The temporal bone is the keystone of the cranium because several m úseles affect its movements. One of the key
facrors in dysfunction of the eran-iomandibular sysrem is distortion and displacement of the temporal bone. The
temporal bone consists of three main parts: the internal petrous porrion, the externa! squama and che mastoid
sections. Squama gives a zygomatic process, which extends forward and articulares with the malar bone and aers
as the shock absorber for the TMJ. In the cranial scheme, the temporal bone articulates with the occiput, parietals,
sphenoid, malar and mandibular condyles. Its primary motion is derived from the occiput, which gently moves
the temporal bones into internal and external rotation during the respi-ratory phases of expiration and inspiration,
Two of the primary muscles oí masrication, tempo-ralis and masseter muscles, have a direct iníluence on the
movement of the temporal bone. The large fan-shaped temporalis partly originates in the temporal squama and
inserts in the mandible at the coronoid process and its anterior border. Contraction of this muscle exerts powerful
down-ward and anterior forcé on the squama when the posterior teeth occlude. This forcé has the effect of causing
external rotation, i.e. rhe superior border of the squama moves anteriorly and laterally while the mastoid tips
move superiorly, posteriorly and medi-ally. The mandibular condyles compénsate by mov-ing posteriorly and
medially within the glenoid fossa.
Internal rotation of the temporal follows a movement that is the direct opposite of external rotation. The mastoid
tips move inferiorly, anteriorly and laterally while the superior border of the squama moves posteriorly and
medially. The condyle com-pensates in anterior and lateral position within the fossa.
Contraction of the sternocleidomastoid, splenius capitis, longis capitis and digastric muscles will induce internal
temporal rotation. The stylohyoid and styioglossus muscles provide balancing movement of the temporal bone.
The muscular attach-ments have their origin in the styloid processes. During contraction they inhibit and balance
the movement of the temporal bone. The arriculation between the temporal squama and the parietal bone is
referred to as a shindylesis joint (joinr with a long bevel). This architectural design provides a
The temporal boneís squamosal suture is fan shaped and flaps over the parietal bone at its junction with the

Two of the primary muscles of mastication, temporalis and masseter muscles, have a direct iníluence on the
temporal bone movement.

This forcé will have an effect of causing an external rotation.

The mandibular condyles compénsate by moving posteriorly and medially within the glenoid fossa.

Contraction of the sternocleidomastoid, splenius capitis, longis capitis and digastric muscles will induce an
internal temporal rotation.

R. Slavicek • The Masticatory Organ

Dental malocclusion with mandibular dis-placement will disrupt the temporomandibu-lar joint function, which in
turn causes temporal bone distortion.
gliding potencial for jamming, espedally when the temporalis muscle goes into a spasm. Dental malocclusion
with mandibular displacement will disrupt the function of the temporomandibular joint, which in turn causes
distortion of the temporal bone"41.
The temporal bone affects the rotating movement OÍ the sphenotemporal articulation, which is formed between
the temporal and sphenoid bones; and temporal occipiral articulation, which is formed between the temporal and
occipital bones. The temporal bone itself rotates in the petrotemporal axis of the pyramidal portion. In recent
orthodon-tics, during occlusion or in conjunction with a pros-thetic construction bite, it was found that the facial
bone is secondariLy affected, once mandibular movement is ttansmitted to the temporal bone.
The midline bones of the cranium provide flexión and extensión movements.

The clinical significance of flexion-extension, a side bending and torsión lesión is that they are usually self-
correcting once the primary lesión is resolved.
Craniofacial Bone Dynamics

The sutural connections between bones permit articular mobility of the cranium. The midline bones of the
cranium allow flexión and extensión (Fig. 13) m. Continuous flexión of the midline bones results in a movement
that reduces the anteroposterior dimensions of the cranial base and increases the lateral transverse dimensión (Fig.
14), while the opposite is true in extensión (Fig. 14). The sphenobasilar articulation is the most important joint
for identifying the resultant motional dynamics of craniofacial function. However, The spheno-occipital
synchondrosis acts as a joint that permits various kinds of motion in different planes such as flexion-extension,
side bending, torsión and strain. The motion of flexion-extension occurs in the vertical plañe, similar to norma!
spheno-basilar joint motion. As a general rule, cranial distortions of flexion-extension are transient. Distottions
are a com-pensatory reaction to ptimary lesions of forces sec-ondary to occlusal function. The clinical significance
of flexion-extension, a side bending and torsión lesión, is that they are usually self-correcting once the primary
lesión has resolved. However, correc-tion of these cranial faults does not have a stable effect; relapses are a
common occurrence.
The normal flexion-extension motion responds around the transverse axis. Bilateral tempotal bones respond to
occlusal function through the temporomandibular joint in a manner referred to as externa! and interna! rotation.
As the bilateral bones go into


externa] tocación, che midline bones go inco flexión. Tooch extracción, defleccive concacc of poseedor teeth,
deviación of the occlusal plañe, hypertonicity of che craniomandibular-hyoid-cetvical conneccion of muscles,
clenching and bruxism, and many other faccors may cause minor co major bone malalign-ment.
As midline bones go inco flexión, the anterior por-tion of the sphenoid rotates downward. This causes the
posterior portion of che ethmoid to tócate downward, with its anterior part rotacing upward. When rocacing
upwatd, it moves posrero-superior-ly under rhe glabella. This, in conjunecion with vomer flaccening and vercical
elongación of che maxilla with external rotación, causes lengrhening and widening of the face.
As che sphenoid goes inco flexión, it descends downward, carrying che vomer againsr che hard palace, causing
che palace co ñateen, and vercical elongation of che maxilla. This is responsible for poor anceroposterior
dimensions of che maxillary bone and also hinders adequace gcowch of che posterior alveolar process for molar
eruprion, tesulting in posterior discrepaney or posrerior crowding. Jn this sense, posterior discrepaney, which
creares sev-eral rypes of malocclusions, is not a genetic prob-lem, but is closely related to the dynamic scate of
craniofacial scructures.
Tooth extracción, deflective concact of posterior teeth, deviación of occlusal plañe, hypertonicity of cranio-
mandibuiar-hyoid-cervical connection of the muscles, clenching and bruxism, and many other factors may cause a
slight co major bone malalignment.

In this sense, posterior discrepaney which acts in creating many malocclusions ís not a genetic problem, but rather
closely related with the dynamic state of craniofacial structure.

Occiput-Spheno-Maxillary Complex with

the Vomer bone

The occiput-spheno-maxillary syscem consises oí the occipuc, sphenoid bone, maxillary bone and vomer bone
(Fig. 7, 10 and 14). The body of che sphenoid forms an imporranc joinc or synchondrosis wich the basilar
process of the occipital bone. This joint fuses in late puberty, indicating that che dynamic moción of che joinc
concinues uncil che terminal stage of functional growth, as a resulc of arriculacion of upper and lower dencicions.
Hanging down from che undersurface of rhe body of che sphenoid bone are two pairs of bony places, the medial
and che laceral pcerygoid place. The lacera] pterygoid piare provides rhe origin of che pcerygoid muscles, which
are responsible for mandibular movement.
The maxillary bone articulaces díreccly with 45% of cranial bones. Sutura! actachments are shared wich

The maxillary bone articulates directly with 45% of the cranial bones.
R. Slavicek • The Masticatory Organ
One of the primary etiologic factors in cran-iomandibular dysfunction is the loss of vertical dimensión.
the malar, frontal, ethmoid, vomer, lacrimal, inferior nasal concha, palarine and sphenoid bones. The forces
generated duting swallowing, speech, chew-ing and parafunctional acrivities such as clenching and bruxing are
direcred via the vomer ro the sphe-no-basilar área, in order ro enhance rhe flexión movement. The posterior
bicuspid and molar axiai root planes are directed wirhin the tange of the spheno-basilar symphysis. Anaromically,
the sphenoid bone is supporred by the vomer bone, whích rests on the palatine bone and exrends vertically to
contact and support the sphenoid near the spheno-basilar junction. Forces from dental contact and the tongue help
to raise the maxilla, palate and vomer, rhereby directing vertical forcé against rhe sphenoid, ensuring adequate
amplitude of the spheno-basilar symphysis inro flexión and influencing era-nial motion.
One of the primary etiologic factors in cran-iomandibnlar dysfuncrion is loss of rhe verrícal dimensión. Lack of
che vertical dimensión as a result of inadequate normal eruption of natural dentition or loss of molar and bicuspid
teeth or severe attri-tion of the occlusal biring surface and inadequate roorh contacc reduces the amplitude of
spheno-basilar flexión and affeets cranial motion (extensión lesión).

Maxillary Bone Growth According to the Dynamics of the Cranial Base

The process of bone displacement, translatory movement of the entire bone caused by the sur-rounding physical
forces, is a primary and charac-teristic mechanism of skull growth. The entire bone is carried away from irs
articular interfaces, sutures, synchondroses, and che condyle with adjacenc bones ,líil. Displacement of the
maxillary complex is caused by che sum of pushing forces from sphe-noidal motion via the vomer bone. It oceurs
paral-lel to bone growth, thus creating space around the contact surfaces into which the bone can enlarge.
The rotating movement of the cranial base oceurs at the spheno-occipital arricularton. The rotating axes of the
sphenoid and occipital bones are the anterior portion of the sella turcica and the posrerior portion of the major
occipital foramen, respectively. The rorating movement of che sphenoid bone is trans-mitted to the mandible
through the vomer, which
Sadao Sato

resuks íq anteroinferior pushing of the maxilla. The vomer has a direct effect on the rotation of the sphenoid, as
the sphenoid and vomer are communicat-ing with the rostrum of the inferior surface of the sphenoid and the wing
of the vomet. In addition, the rotating movement of the sphenoid bone is inditectly transmitted to the maxilla
because the inferior border of the vomer is connected to the maxillopalatine process and the nasal crest of the
palatine horizontal píate. This is how the move-menr of cranial bones affects the maxilla, especially when the
pushing direction of the maxilla changes in relation to the rotating direction of the cranial base; this would
indícate growth of the maxilla. For example, rotation of the sphenoid bone is flexión. This would influence the
rotating forcé of the wing of the vomer, which is posteroinferior, prevenring anterior pushing of the maxilla.
Instead, it would move inferioriy. On the othet hand, when the rotation of the sphenoid bone is extensión,
rotation of the vomer will be anterior, and rhe maxilla will be strongly pushed anteriorly. The pushing movement
of the maxilla affords adequate space in the posterior portion of the upper teeth, allowing growth of the posterior
border of the maxillary tuberosity.
The direction of displacement of the maxilla is influenced by the dynamic states of the occiput-spheno-ethmoidal
connecrion of the cranial base. There are three types of maxillaty growth secondary to displacement of the
maxillary compiex: transla-tion with the frontal bone, vertical elongation, and anterior rotation (Precious et altl7),
1987) (Fig. 15).
Flexión motion of. the cranial base causes vertical elongation of the maxillary compiex. This is com-monly seen
in the dcvelopment of a Class III skele-tal frame. Extensión of the cranial base causes anterior rotation of the
maxillary compiex. This is relat-ed to the development of a Class II skeíetal frame.
Transtation of the maxilla (antetoposterior) with the frontal bone to which it is attached below the frontal sinus
shifts the maxilla in forward direction. The maxilla is passively displaced due to expansión of the middle cranial
fossa, the anterior cranial base, and the forehead, without the growth process of maxilla itself being directly
involved. Vertical elongation of maxillary compiex and the formation of rhe alveolar process increase the height
of the maxilla.
Bone deposition on the wall of the maxillary tuberosity is mainly important tor crearing space ro allow the
eruption of posterior teeth, resuking in
The rotating movement of the sphenoid bone is transmitted to the mandible through the vomer, which results to
the anteroinferior pushing of the maxilla.

R. Slavicek • The Masticatory Organ

posterior lengthcning of the bony maxillary arch. This

posterior elongation of the upper jaw is couplet! with
translation and anterior rotation of the maxillary
complex, akhough the vertical elongación of maxillary
bone does not provide posterior lengthcning (Fig. 16).
The cooth buds of the upper molars have to be formed
in the relatively small área of the maxillary tuberosity,
indicating posterior discrepaney ilB,lS11, As the
maxilla displaces by forward translation and anterior
rotation, the formación of the alveolar process
accompanies the downward movement of tooth buds.
Thus, posterior crowding of the molars is eliminated.

Temporo-Mandibular Complex

The temporo-mandibular complex is une of the most important functioning systems of the cranium.
Each temporal bone consists of the squamous, petrous and mastoid portions.
The temporo-mandibular compiex is one of the most important functioning systems of the cranium. In the
functional cranial scheme, a U-shaped mandible, representing the most active functional movement in craniofacial
structures, conneets the two temporal bones at the lateral surface of the cranium. The temporo-mandibular system
is com-posed of the articulation of the mandible with the cranium; this joint is referred to as the temporo-
mandibular joint. The mandible and temporal bones affect their posición and movement recipro-cally (Fig. 17).
Each temporal bone consists of the squamous, petrous and mastoid portions. They also have other distinct parts
such as the tympanic píate and tlie styloid process. The parietal notch of the temporal bone articulates with the
mastoid angle of the parietal bone located above the mastoid process. A fur-ther unique characteristic of the
temporal bone is that the squamous temporal considerably overlaps the parietal bone, racher chan incerdigitating,
as many cranial bones do. The type of articulation that oceurs between the temporal, occipital and parietal bones
in the cranium may well reflect the large masticatory forces generated around the cranium. In addition to the
overlapping articulation that oceurs in all hominoid crania, che pariecal bone overlaps with the mastoid portion of
the cemporal bone as well as with the occipital bone. Rak (1978)(2S| and Kimbei and Rak (1985) B " reported
that this migbt be due to the resistance to extreme masticatory stresses in the vault bones of this región. The
condition of overlapping vault bones

Sadao Sato

appears to be a unique adaptación among fiomi-


The Importance of the Function of

Occlusion for Mandibular Growth

h has long been believed that the growing enlarge-ment of condylar cartilage was the primary reason for
mandibular displacement. According to this concept, the pressures exerted on the glenoid cavity by the growing
conciyie caused the mandible to be displaced out of articulator contact m,
Two simple questions may be raised in an attempt to explain clinical experience and the aiticulation of teeth.
First, how do the upper and lower teeth fit together if the mandible is displaced by predeter-mined condylar
growth? Second, is the maxillary bone, includíng upper dentition, adaptable to the continuously changing
mandibular dentition?
Recent studics showed that mandibular displacement is the primary process and that condylar growth is secondary
and adaptive. This reestablish-es the relationship of the displaced mandible in the temporomandibular joint
The mandible is greatly influenced by functíonal demands, especialíy the articulation. Thcse are con-crolled by
the central nerve-muscle system. According to Moss, a specific cranial component controls each function while
the size, shape anci spa-tial position of the individual components are rela-tively independent of each other.
The functional matrix includes the functioning space and the soft tissue components required for a specific
function such as breathing or mastication. The function of the mandible is always executed in relation to the
spatiaüy positioned upper dentition (Fig. 18). Mandibular translation is caused by the functional shift of the
mandible, which is induced by the functional articulation of teeth. The entire mandible is displaced downward
and forward, away from íts articular joints.
This translatory movement stimulates the enlarge-ment and remodeling of the condyles and the rami, which take
place parallel to displacement. Bone growth processes are directed upward and back-ward to an extent that equals
the displacement of the mandible. From this standpoint of the mastica-tory system, the cranial determinant of
mandibular growth is the spatial position of maxillary teeth.
However, recent studies showed that mandibular displacement is che primary process and condylar growth is
secondary and adaptive.

R. Slavicek • The Masticatory Organ

Craniofacial Growth and

Development with Specia! Attention
on the Occlusal Plañe

The most significanc point in the cybernetic model is that occlusal function is an impor-
tant factor in the mandibular growth.

The most important point in this concept is that mandibular growth is not only controlled by the endocrine
systcm and intrínsic capacity of the mandibular growth, but also the posición of the occlusal surface {functional
occlusal plañe) of the maxillary teeth to which it is functioning wich.
Petrovic (1975) (2Í''27' comprehensively studied fac-tors affecting the growth of the maxillofacial skulJ. As a
result, he described the cybernetic model of mandibular growth using Moss' concept as his fun-dament (JS'M>.
The most significant point in the cybernetic model is that occlusal function ¡s an important factor in mandibular
growth '■''■'. In anteroinferior displacement of the maxilla, the mandible is able to functionally adapt. This
displacement clirects adaptation of mandibular growth. In the cybernetic model, the functional factor that regulates
mandibular growth is occlusal function.
The cybernetic model of Petrovic can be simptified in the manner shown in Fig. 19. The most important local
factor in the control of mandibular growth is the spacial position of the maxillary occlusal surfaces and the
maxillary dental arch. Functional movement of the mandible is dependent on the action of the central nervous
system and masticatory muscles. Anteroinferior growth of the maxilla functionally shifts the mandible, making
the TMJ adjust to the new mandibular posirion, which leads to mandibular remodeling or growth.
system and the ¡ntrinsic capacity oí mandibular growth, but also by the position of the occlusal surface
(functional occlusal plañe) of the maxillary ceeth, with which it is functioning. For instance, in a pacient in
whom the maxilla descends vertically, the functional occlusal surface will change to inferior posirion. In response
to this, the mandible will move inferiorly and etongate vertically (Fig. 20).
Moteover, adaptación to the new mandibular position is not always simply due to mandibular growrb and
internal remodeling of temporomandibular joint. The functional forcé from the mandible to the temporal bone
through the joint, the masseter mus-ele, changes in traction forcé from the masticacory muscles to the temporal
bone, and movement or rotación of the temporal bone, are liable to alter positional adaptation of the mandible.
In addition, the tensión of che medial and laceral pterygoid process, which is relaced to the positional

Sadao Sato

change of the mandible, affects rotación of the sphe-noid bone. Movement of the sphenoid bone changes
maxiliary movement and the vertical posición through the vomer. The altered mandibular posición due to
occlusion controls the harmony of the entire maxillofacial skeieton.
Occlusal function and the maxillofacial skeieton are closely relatcd, creating a unified dynamic mecha-nism. The
balance of this dynamic mechanism has a great influence on the growth of the maxillofacial skeieton in active
infants. Therefore, orthodontic occlusal treatment is not simply an alterarion of occlusion but che consideration of
a maxillofacial dynamic mechanism. This type of mandibular adaptation to occlusion causes a load on the
mandibular condyle, where its growth will be regu-lated. However, when this load exceeds the adap-tive capacity
of the TMJ, it affects function in the temporal bone, articular disc, and masticatory mus-cíes, causing TMJ
On the other hand, an increase in the vertical dimensión that exceeds the growth of the mandibular condyle
results in rotation of the mandible, pre-senting an open bite condition of the front teeth and creating a fulcrum in
the molars, which in chis case causes an abnormal load for the TMJ.
As mentioned earlier, the increase in che vertical dimensión and mandibular growth are closely relat-ed. It is
important co develop and maincain che harmony of both. Once the vertical dimensión mercases or decreases, the
mandible adapts through func-tional displacement.
The occlusal plañe is the most important compo-nenc influencing che vercical dimensions of che lower face, For
insrance, the vertical position of posterior teeth in a Class III high angle and in open bite malocclusion is not
stable during growth (Fig. 21). Continuous molar eruption oceurs noc only during growth, buc also during post-
puberty. In this sense, genecics may noc be che solé reason for this type of malocclusion. Rather, the continued
eruption of second and third molars in a limited space must be che major concriburing factor. The development
of such malocchtsions must be regard-ed as an effect of posterior discrepaney or posterior crowding ll2-yy'.

The occlusal function and the maxillofacial skele ton are closely related, creating a whole dynamic mechanism.

R. Slavicek • The Masticatory Organ

Cephalometric Evaluation of the Denture Frame (Denture Frame Analysis)

The skeleton, whose shape is directly related to occlusion and is the basic unit that supports the maxilla and
mandible, is known as the denture frame. Since the denture frame is a basic skeleton chat supports the upper and
lower dentition, it must be in harmony, especially with the occlusal plañe. The denrure frame changes in response
to occlusal changes because mandibular displacemenr affects it. The changes associated with its morphol-ogy and
growth are closely related to occlusal func-tion.
Occlusal construcción is the most important mea-sure for establishing the sparial position of the occlusal plañe in
the denture frame. In other words, orthodontic occlusal treatment restores the harmony of the denture frame and
occlusion through attaining a correcr occlusal plañe. From this stand-point, denture frame analysis is done to
determine the basic morphology of the denture frame <M).
The palatal plañe (PP), occlusal plañe (OP), mandibular plañe (MP) and AB plañe (AB) of the morphology of the
denture frame are closely related to occlusal funcrion. Listed below are the refer-ence points and planes used in
denture frame analysis (Fig. 22).

l.FH plañe (FH)

Palatal plañe (PP)
Mandibular plañe (MP)
AB plañe (AB)
Occlusal plañe (OP)
A', 6", A'-F 6'-P
Maxillary median incisal axis
Mandibular median incisal axis
9- lst molar axis of the upper and lower mandible

Denture frame analysis is measured with the above mentioned Ítems, which are also studied with regard to their
respective functional background.
This determines the position of the denture frame in the craniofacial skeleton and is an importanr índex to
determine the functional adaptation capacity of the mandible to occlusion. When the FH-MP is high, the
functional adaptation capacity due to anterior rotation of the mandible to the occlusion is low.
Usually, when the mandible shows excellent adaptation capacity due to its growth, it displays pro-trusive
rotation. However, when the adaptation capacity is poor, it usually displays a retruded rotation. In case of
protrusive rotation with bone remodeling of the inferior border of the mandible, there is a minimal change in the
FH-MP angle while the AB plañe and the MP angle decrease due to the prottusive position of the mandible (Fig.
21). In case of retruded rotation, the FH-MP angle increases, with minimal changes in the AB-MP angle. This
presents the so-called high angle condi-tion.

It is the angle formed between the palatal plañe (PP) and the mandibular plañe (MP). This shows the basíc
morphology of the denture frame. When this is increased, like the FH-MP, it docs not induce protrusive rotation
of the mandible as a functional response; rather it adapts to the occlusion through backward rotation. Although
the PP-MP and the FH-MP are nearly the same, the sígnificant differ-ence lies in the descent of the palatal plañe
due to the protrusive rotation of the maxilla. This is usually observed in patients with mandibular dístocclu-sion
associated with deep overbite.

This is the angle of the occlusal plañe (OP) and the mandibular plañe (MP). Normally, the occlusal plañe and the
mandible have a functional relation-ship in order to maintain the OP-MP angle with neuromuscular function. In
othet worcSs, when the occlusal plañe changes to parallel or slightly horizontal during the growth process, the
mandibular plañe also moves in parallel to it. Even ¡f the occlusal plañe is changed to horizontal, the mandible
reaets to maintain the OP-MP angle by rotating protrusively in response to the occlusal plañe.
This phenomenon is also seen in individuáis with notmal occlusion, and slight changes of the occlusal plañe are
recovered through this type of mandibular adaptation. This does not result in a serious occlusal abnormality
because it maintains the func-tional occlusion. However, when the occlusal plañe is excessively displaced, it
results in a backward rotation of the mandible, leading to an increase in the OP-MP angle.
Since the vertical support of the occlusion is insuffi-cient, mandibular condyle growth is inhibited. The OP-MP
angle does not adapt forward and remains decreased even during the growth process. The angle of the OP-MP is
not merely the angle formed between the occlusal plañe and mandibular plañe. It is the measurement of the
reiationship of the occlusal plañe and the mandibular plañe as a functional unit of the denture frame, which has a
dynamic relarionship with the functional adaptation capacity of the mandible.

This is the ratio of the OP-MP angle to the PP-MP angle. In effect, it shows the positional reiationship of the
denture frame and the occlusal plañe. The valué of a normal occlusal plañe is 0.54; which is the basic
morphology of the denture frame. If it exceeds 0.60 it is presumed that there is a deviation of the occlusal plañe
and that the mandible is not adapting to it. In an occlusal plañe of less than 0.5, the posterior vertical dimensión
is insufficient, which leads to a retruded mandible brought about by the inhibition of the mandibular condylar
growth due to a chronic compression load.

This is the angle formed between the AB plañe, the point of A and B, and the mandibular plañe (MP). It reveáis
the anterior border of the denture frame and the anteroposterior reiationship of the lower and upper jaws. This
usually shows the anterior dis-placement of the mandible due to its forward rotation. When there ¡s over-eruption
in the molar part, rhe mandible avoids the posterior interference through protrusive displacement. Persistenr
push-ing of the molar in posterior discrepaney allows protrusive displacement to oceur contínuously, which
somehow affeets the mandibular condyle growth and alters the denture frame morphology. There is a mutual
reiationship between the change of the occlusal plañe and the change of the AB
plañe, which resuics in an alteration of che occlusal plañe to fíat, associatecl with a reduction of the AB-MP
angle. Howevet, when the adaptation capacity of the mandible is lew, there is no change in the AB-MP angle,
and there is a tendeney for the PP-MP to increase.

It is the distance between the A and P. This repre-sents the anteropostetior diameter of the maxillaty basal bone.
The A'-P in a 6-year-old child with a normal occlusion is 44.1 ram. and this gradually increases during growth.
At the age of 13 years it becomes 50.0 mm. and is nearly consistent there -aftet.
The increase of A'-P' is btought about by the growth of the bone in the posterior border of the maxillary
tuberosity. However when the growth in this pare is decreased, the A -P angle is sustained, ieading to an
insufficient space in the posterior den-títion, resulting in posterior discrepaney.

It is the distance between che A' and 6'. This shows the protrusive length of the lst molar in the maxillary basal
bone. In an individual with a normal occlusion and without posterior discrepaney, the distance nearly does not
change at all and the lst molar position is extremeiy stable during the growth period.
However, in a patient with posterior discrepaney, A'-ó ' decreases because of the erupción of che 2nd and 3rd
molar associated with the mesial move-ment and the vertical pushing on the lst molar. In effect, both the mesial
movement and supraerup-tion are forms of posterior discrepaney. The degree of posterior discrepaney can be
estimated with the A'-ó' parameter.

This is the ratio of the valúes measured above. It shows the anteroposterior position of the lst molar tooth in the
maxillary basal bone.

0 Denture frame of the upper and lower frontal teeth and the measurement of the relationship of tipping and
position of the molar.
R. Slavicek • The Masticatory Organ

1 - AB (°): the angle formed between the tooth axis of the maxillaty central incisor and the AB plañe.
1 _ AB (mm): the distance from the incisal inar-gin of the maxillary centra! incisor to the AB plañe.
1-AB(D): the angle formed between the tooth axis of the mandibular central incisor and the AB plañe.
1 -AB (mm): the distance from the incisal mar-gin of the mandibular central incisor to the AB plañe.
ínter-molar (°):the angle formed between the tooth axis of the upper and the lower lst molar.

The angle and position of the frontal teeth are all evaluated through the relationship of the AB plañe. Changes in
the AB plañe are due to maxillary rota-tion and adaptational change of mandibular position to the occlusal plañe.
Moreover, the AB plañe and the occlusal plañe are nearly at right angles to each other, and this reflects the
adaptive capactty of the mandible to changes in the occlusal plañe. For example, the vertical dimensión does
not increase when there is a steep occlusal plañe; the AB-MP angle increases because the mandible adapts
to it. As a result, there is the relationship of the occlusal plañe to the tright angle. On the other hand, when the
occlusal plañe changes to fíat, the mandible takes the protruded position and the AB-MP angle decreases, thus
maintaining the relationship of the occlusal plañe to the right angLe. The first molar axis has the most stable
centric stops when the occlusal forcé is in vertical direction. However, in a patient with posterior discrepancy,
mesial tipping is usually extensive and this has to be uprighted through an orthodontic occlusal recon-struction.
Uprighting of the molars provides space for the dental arch, which offers the possibility to improve crowding and

Impl¡catión for Dental Practice -Developmental Mechanism of Growth


Research studies of rnaxiilofacial skull growth occu-py an important position in dental and orthodontics

research studies. When continuing the occlusa! management of an orthodontic patient, ir is important co noce rhar
che important elements of the maxillofacial growth concept are certainly within the maxilla and che mandible.
The growth of the mandible chrough time disregards the orthodontic approach and the efforts of both the surgeon
and the patient are instantly wasted.
Various orthodontists are puzzled by the thought chat the growth phenomenon is nothing but abnor-malicy.
Whac, then, is che mechanism of chis type of growth abnormality? To ascertain this, it is by all means important
to conduct a very accurate occlusal reconstruction.
As mentioned, environmental faccors have a srrong influence on the maxillofacial skuil growth afcer birth and,
more importantly, in che dynamic func-cion of the stomatognachic syseem. Without doubt, the abnormalities of
occlusal funecion could easily displace the mandible. In facr, various malocclu-sions show a displacement of the
mandible from the center position. Moreover, this displacement in mal-occlusions increases with age (Fig. 22).
As understood in the cybernetic model of Petrovic, mandibular displacement. mediated by the neuro-muscular
system, induces secondary growth of the condyle. A persistent mandibular displacement consequently results in
displacement of the skelecal morphology. According ro Moss, che latent growth capacity of the cartilage is
excremely low. Mandibular elongation is explained as a secondary or compensatory growth, which is achieved
through the functional displacement of the mandible, relat-ed to the prorrusive movement of the maxilla.
If this is true, it may be concluded chat the abnor-malicy in mandibular growch is actually an abnor-mal
adaptation to occlusal function in the normal skeletal pattern. Moreover, the sudden increase in the abnormality of
the TMJ, post puberty, creates an abnormal occlusal function which makes the mandibular condyle adapt by
means of immense growth. This growth, however, diminishes the growth capacity of the mandibular condyle.
Either way, the abnormal growth is assumed to be proba-bly caused by the functional factor of the
stomatognachic system in occlusal function. In the field of orthodontics, it was long believed that growth-related
development was the basic cul-prit. Orthodontists blame the growth factor to be che unknown cause of skeletal
malocclusion. In case of no response co malocclusion treacmenr, or when
Sadao Sato
the anticipated growth does not match with skele-tal changes, or if there is recurrence of malocclusion after
surgical treatment, abnormal growth may be considered co be the underlying cause. All inconve-nient
circumstances for the orthodontist are due to growth. If growth-related development alone is, indeed, the cause of
the development of malocclusion, it would be impossible to disregard such development and simply improve
malocclusion. In the long run, we cannot help but disregard orthodontic treatment.
To assert that growth is the culprit of all, as men-tioned a while ago, is incorrect. Rather, the abnormal growth
pattern is the result of mandibular adaptation related to occlusal function abnormality. Therefore, early orthodontic
management has a very important implication in the harmony of max-illofacial skeleton growth. This víewpoint
is important in reconsidering the developmental process of skeletal malocclusion.
Management does not end with tooth replacement, especially in occlusal training and occlusal guid-ance. The
harmony of the maxillofacia) skeleton and the management of the entire growth are important. In order to achieve
these, it is important to understand the relationship between occlusa! development, the maxillofacial skeleton,
and the development of specific skeletal growth abnormality. This theory is merely based on the dynamic
mechanism of the maxillofacial skeleton and the developmental mechanism of skeletal malocclusion.
- Sadao Sato

Figure la and Ib: Composición of the craniofacial complex. The skull consists of severa! difTerenc sophisdcated bones that collectively
fonn a hollow bony shell rhar isouses the brain and sense organs, and provides a base for the teerh and rhe chewing muscles. In the stage
of growth, the bones are in a flexible srare and are dynamically incerrelated. The cornponcnts also have che ability to adapt to fonctions of
the skull. The skull functions as a base and a srrucrural framework for the first stage of the digescive system and mastica-tory organ. It also
serves as an cncasement for che brain and fnr the sense organs of sight, smell, and hearing. The functional balance of craníolacial bones is
influenced by occlusa! funccions such as masticación, respiration, spcech, clenching and bruxism.

Figure 2a and 2b: Composición of the skull of humans and primaces. Thc- conneccion of che Occipital-Sphenoid-Vomer-Maxillary bones
in the primate skull (a) shows an expanded and longer anteroposterior dimensión tlia n that in humans; (b) che human skull indicates
expansión of the ncnrocranium and reduction ot facial prognachism. A shift ín che posición of che foramen magnum can be seen due to
thc uprighting effecc of che skull and che mercase in brain size. As a consequence ol the great reducrion in che anreroposccrior dimen-
sions of che viscerocranium, the human skull exhibited wider and more verrical growch than the primare one.

R. Slavicek * The Masticatory Organ

Figuce 3a and 3b: Comparison of cephalogram ccacings of human and primare skulls. lo contrast ro humar», primaces have a large crania)
base angle (N-S-Ba) with a posteriorly located foramen magnum and forward translation of che vomec and che maxillarv bone. The
modern human face cends co cotate backward and downward underneach the brain case, with the brain developing on che top of che
facial skeleton. The human cranial base located between che face and the brain assumes a Iarger bend, thereby reducing rhe degree of
flexure (N-S-Ba) compaced to chac in primaces.
Figure 4: Supemnposirion of cephalogram tracings feom mod- Figure 5: Vcrticalization of the viscerocranium during ontoge-
ern humans and primates. This superimposicion indicares how neric growth and development. As rhe viscerocranium increas-
the flexure of rhe cranial base angle is related to changes in es in its vertical rather chan anteroposterior dimensions, the
rhe craniofacial skeleton. Reducción of che ccanial base angle facial complex of the modern human creares rhe necessiry of
grcatly influences the facial profile and che dirección of growch functional mandibular adaptación in order co fu upper and
of the maxillary complex. lower denticions.

Sadao Sato

Figure 6a and 6b: Adaptation of occlusion against verticalized growth ofrlie facial skeleron. Vertical growth of the viscerocranium ¡n
rhe human skull creates an anterior open bite (a); the maxillary complex rranslares downward. resulting in posrerior contact of the
upper and lower tcetli (wedge effect). Functions of the anrerior mimic musties such as the orbicularis oris, mentalis, depressor and
leva-ror anguli oris, and buccinator mtiscles, include closing the mandible and helping to adapt the mandible by rotational movement, so
that it flts with thc upper and lower occlusal surfaecs (b). Patients with weak mimic muscle activity develop an anterior open bite mal-
occlusion, as thc mandible cannot adapt through rotation.

. i '



Figure 7: Craniofacial conoecrion of the Occiput-Sphenoid-Vomer-Max.illary bones. The sphenoid bonc is located in the cenrer ot che skull
and jains wich other mid-line bones such as che occiput, ethmoid, and vomer. lt is direedy connected to the maxillary bone via the vomer
and palatine bones. The sphenoid bone is also connected to the occipica! bone by a syn-chondrosis kitown as the spheno-occipital
synchondrosis. which is in dynamic motion during rhe developmenc of occlusion. Thc- dynamic motion of the crania! base is cransferred to
thc maxillary bonc through tbe vomer bone.
Figure 8: Temporo-mandibular camplex. The mandible is connected with the temporal bone through the temporomandibu-lai joinr. The
camplex is the mosc dynamic functional unit in the ctaniofacial skeleton. Dynamic movement of this complex influcnces the statc of the
Occipuc-Spheno-Maxillary complex.

R. Siavicek • The Masticatory Organ
Figure 9: Connection ot the sphenoíd and temporal bones. The vertical and horizontal portion of the greater wing of the sphenoid and
témpora! bone are interconnectcd by a heavy butt joint (arrow). The dynamics oí" the temporal bone inflti-ence the spheno-occípiral
balance of the cranial base through chis heavy joint. If the glenoid fossa were to receive compres-sion forcé from occlusion, especially
when the upper and lower reeth grind strongly during bruxism, the forces would be rransferred to the ctanial base via the rotationai
movement of the temporal bone.
Figutc 10: Tbe dynarnic connection of the Sphenoid-Vomer-Maxillary bones. The vomer bone plays an important role in ttansferring ctanial
motion to the maxillary bone. Therefore: the motion of the craniai base influences displacement of the maxillary bone.

Figure 11: Connection oí mid-line bones and bilateral temporal bones. The mid-line bones of the cranium undergo a motion defined as
flexión and extensión. Two of the mid-line bones, the greatet wings of sphenoid and occiput, articúlate with the petrous porción of the
temporal bone. Thís pettotis extensión acts as a totational axis (petto-temporal axis) during motional activities.
Figure 12: Dynamics of the Temporo- Pariera I suture, The long bevcled suture of temporo-parietal bones possesses the ability ofgliding
movement. Reciprocating movements of the suture from external forces adjust themselves to balance cranial bones. The presence of
malocckisían wíll disrupt the temporo-mandibular joint, resulting in mandibular displacement, which in tutn causes discottion of the tempotal


Figure- 13: Sagittal connccrion ofthe Occipat-Sphenok!-Vomer-Maxillary bones. The flexion-extension motion ofthe cranial base
iníluences the dirección of maxillary bone dis-placcmenc, followed by sutural growth.
Figure 14a, 14b and 14c: Sagittal expression ofthe relation shíp between motion ofthe cranial base and disphicemcnt of the maxillaty
complex. Flexión ofthe cranial base causes vertí-cal elongación ofthe maxílla while extensión causes anterior rotation ofthe maxillaty

Figure ]4b
Figure 14c

R. Slavicek • The Masticatory Organ
Figure 15c and 15d

Figure 15a-15d: Different types of maxillary booe displáceme»!:. There are 3 rypes of maxillary displacement: translation (b), veccical
eiongarion (c), and anterior rocacion (d), according co che growch study done by Precious er al. (1987). Ic was suggesced chat che
differenc types of maxillary displacement were closely refaced with cranial growth and cranial moción. Inccease of che anterior crania!
base causes cranslacional displacement of che maxillary complex. The flexión motion of che cranial base induces veccical elongación of
che maxilla while extensión provides ancerior rotation of the maxilla, as shown by an ancerior-upwacd inclinación of che palatal plañe on
che cephalogram,
Sadao Sato

Figure 16; Growth ofthe upper ¡aw and eruption oí posterior reetli. Most of the growth in the anteroposterior dimensions ol
the maxilia originares through bone apposition from the posterior aspect to the maxillary cubcrosity. The inicial
appositional growth at the tuberosity arises with forward translation ofthe maxillary complex. Lack of maxillary translation
makes k difficult co provide eruption space for the posterioi molars; this creates posterior dis-crepanty.

Figure 17a and 17b: Frontal view ofthe craniofaciai complex. Connecrion and poscurc ofsphenoid, temporal bone, vomer, maxilia, and
mandible are elosely interrelated with tbe dynamic kmcrion ofocclusion (a). Unilateral over-eruption of posterior teecb creates posterior
interference and induces a mandibular lateral shilc. Ci>nsec|ucnrly the individual dcveksps an asymmecrical balance ofthe craniofaciai
complex {b).

R. Slavicek • The Masticatory Organ

Figure ISa and 18b: Functíon of occlusion and mandibular growth. In che growing facial skeleton, adaptabdity is primarily located in tile
functíon of dentición and secondarily in thc sutures and ar the condyies. The growtli of che lower face is guidcd by che function of
occiusion, followed by secondary condylar growch. Thus, che chrce-dimensional change of the occiusal plañe is an extremely ímportant
determinanc of facial growth (a). Hori2ontalization of thc maxillary occiusal plañe provides rotarional mandibular udaptation, wirii a
simultaneous reduction in the mandibular plañe angic (b).
Figure 19: Denture frame analysis of che lower face. Palatal Figure 20: Longitudinal changes in che dencure frame in a
plañe (PP). mandibulac plañe (MP), maxillary occiusal plañe normally growing subject. The pattern of mandibular growth
(OP), and AB plañe (AB) are used to assess rhe conscruction of is closely relaccd to changes in the spatíal position and inclina-
the lower face. The Frankfort horizontal plañe (FH) is used as cion of the upper occiusal plañe.
a ctanial reference line,

Sadao Sato

Figure 21a and 21b: Longitudinal growtli paccerns ofdenrure frame in cases developed skeletal Class II! (a) and Class II open bite (b)
malocclusions. Alreration of occlusal plañe related not only with mandibular posttire, but also with dynamic srace of the cranial base.

Figure 22a and 22b: Shows twa adults with skeletal Class III (a) and skeletal Class II (b) malocclusions. Differenccs in the length and angle
of cranial base, posirion and inclination of che occlusal plañe, position and postare of the maxilla and mandible, and dento-alveo-lar
vertical heighr are seen.

R. Slavicek • The Masticatory Organ

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2. Rctzlaff, E, Ernest, W: The structures of cranial bone sutures. J. Am. Osteop. Assoc. 607-608, 1976
3- Frymann, VM.: A study of the rhyrhmic motions of the living cranium. Journal of the American Osteo. Assn. 1:70,1971
Frymann, VM.: Relación of disturbances of craniosacral mechanisms co symptomatology of the newborn: srudy of 1,250 infanes, J. Am.
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Kragt, G.: Measuremenr of bone displacemenr in a macera-red human skuli induced by orrhodontk fortes: A hologra-phic study. J.
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Latham, RA: The sliding ot cranial bones at sutural surfaces during growth. J. Anat. 103:593, 1968
Blum, C: The effect ofmovemenr, stress and mechanoeiec-tríc aetivicy within the cranial matrix. lat. J. Orrhodonr. 25:6-14, 1987
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Wood,J,; Dynamic response of human cranial bones. j. Biomech. 4:1-12, 1971
Gillespie, B.R.: Dental considerations ot craniosacral mechanism. J. Craniomand. Pract. 3:380-384, 1985
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Cousin, R.R, Fciiarr, R.: Etude Ontogenetique des Elemems Saginaux du Fossc Cerebrale Anterieure chez líHomme Orientation
Vestibulaire. Archives Anat. Path. 9:383-395, 197 1
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Uplcdger, John E., Rctzlaff, Ernest W., Vrcdevoogd, M.F.: Diagnosis and treatment of Tempuro-parictal suture head pain. Ostcopathic
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Flooper, H.: Cranio-gnathic implication. In Orrhopedic Gnarhology. Hockel, J.L. and Creek, W (ed.) Quintessence Publishing Co., Inc, pp
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McNamara, J. A. Jr.: N'euromuscular and skeletal adaptarions to altered funcrion in the orofacial región. Am.J. Orthod. 64:578-606, 1973
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- Sadao Sato