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Developmental facial abnormalities and the temporomandibular joint
Developmental facial abnormalities and the temporomandibular joint
Bernard G. Sarnat,
MD, DDS, Beverly Hills, Calif
Eruption of the teeth and normal development of the mandible as well as some portions of the upper jaw and face are related to function of the growth center in the mandibular condyle. Abnormalities may occur when the activities of this center are either stimulated or depressed by disease or injury. Factors influencing apposition and resorption of bone further modify the growth pattern of the TMJ and face.
The dynamics of the growth of bones are compli cated. Although the basic blueprint of a bone is inherent, the form and architecture may be modi fied during prenatal and postnatal growth by lo cal and systemic influences acting upon various
GROW TH 8 Weeks
FftTTERN OF PIG
16 Weeks
CONTROL
M A N D IB L E I
I 2 0 Weeks
Fig 1 ■ Serial tracings of lateral cephalom etric radiographs of m andible of grow ing pig superposed on o u tlin e s o f fo u r radiopaque im plants. Note superior and posterior d irection and am ount of growth in region o f condyle and posterior border o f ramus. See Fig 2.
108
growth centers and sites. The end result at any given tim e is a record of the effects of all the vicis situdes. The group of bones comprising the tem porom andibular joint and face is no exception. A n integral part of the TM J, the mandibular condyle, bears a site o f endochondral bone forma tion, the condylar cartilage. Appositional growth of this portion of the condyle contributes directly to the increase of mandibular height and length, and indirectly to eruption of the teeth and devel opment of portions of the upper jaw and face. Growth of the condyle and ramus is in a superior and posterior direction (Fig 1). Because o f the articulation of the condyle in the mandibular fos sa, the mandible moves downward and forward (Fig 2). The cartilage in the head of the mandible
Fig 2 ■ Superposed tracings o f lateral cephalom etric radio graphs o f norm al human co n tro l at 5 years 5 m onths, 10 years 5 m onths, and 15 years 7 m onths. A lthough condyle and ramus grow superiorly and posteriorly, m andible a ctually moves downward and forw ard because of a rticu la tio n of condyle in m andibular fossa. See Fig 1.
bances of the condyle and related structures. They range from under- or overdevelopment of only one condyle to under- or overdevelopment of the entire face. All of these conditions can result in facial, as well as occlusal, disharmonies. Any al teration in the size and shape of the condyloid process affects the TMJ. Since the mandible is a single bone, change in one joint will be reflected in the opposite one. In some instances of a general disturbance, changes in the TMJ are only part of the total effect. The resulting malfunctions of the TMJs are manifested by a number of clinical signs (Table). This report is not meant to be all-inclusive but rather to present selected material which can serve as a basis for further study. For additional and de tailed information, other sources are available.1-9
is homologous neither to an epiphyseal cartilage, because it is not interposed between two bony parts, nor to articular cartilage, because the con dylar surface is covered by fibrous tissue. The con dylar cartilage is, however, homologous to that in the head of the clavicle. The histologic arrange ment of tissues is not the same at all centers of endochondral bone growth (Fig 3). On the basis of this difference, certain clinical problems can be explained.
Facial abnormalities and condylar growth activity There are many causes for the various unilateral (Fig 4, 6) and bilateral (Fig 5, 7) growth distur
Table ■ P o s itio n o f m id lin e of ch in a n d o th e r c lin ic a l fin d in g s in d iffe re n tia l d ia g n o s is o f te m p o ro m a n d ib u la r jo in t c o n d itio n s . Midline of chin
C o n d y la r motion
Con dition
Mouth closed
Mouth open
N o r m al
No deviation
No deviation
None
A n t er io r dislocation (u nilateral)
Deviation to unaffected side
Deviation is dec reased
P r om in e n ce of chin on the side unaffected
M a n di b ul a r teeth buccal to maxillary on unaffected side
An te ri or dislocation ( b il at e ra l)
No deviation
No deviation
S ym m e tr ic al p ro m in e nc e of chin
P r em a t ur e m ol ar contact a n d anteriorly op ene d bite
No deviation
Deviation to affected side
May have swelling in associated areas of t ra u m a or fracture
Un u su a lly un c ha nge d
No deviation
No deviation
Retropositioning of mand ible
P r em a t ur e mo la r contact a nd anteriorly opened bite
No deviation
Deviation to affected side
None
Us ually un c ha nge d
Unaffected side flat; chin a pp ea rs p ro m i n e n t on affected side
Fracture d dislocated condyloid process (u n i la t e r a l) Fracture d dislocated condyloid process (b il a t e r a l) Partial ankylosis without gro wt h a rre st ( un ilateral) Partial ankylosis with growth arrest (u n i la t e r a l)
T u m o r of condyle
Deviation to affected side Deviation to unaffected side
Deviation is increased
Facial de formity
Deviation IS
decreased
G ro w th arre st (u ni la t er a l)
Deviation to affected side
Deviation is increased
Growth arre st (b i la t e r al )
No deviation
No deviation
Chin a p p ea rs p r o m in e nt on unaffected side
Unaffected side flat; chin ap p ea rs p ro m i n e n t on affected side M a r ke d sym me tr ica l u n d e r d e v el op m en t of chin and ma ndi bl e
Occlusion
Unaffected side
Affected side
Degree of op en in g
Normal
H in g e and glide
Hi nge and glide
Norm al
Hi nge and glide
Slight hinge and rotation
Limited b y muscle spas m on affected side
Slight hinge
Ma n d i b le fixed in limited op en position
No ne
Limited
None
Ve r y limited
Hinge and glide
Slight hinge
Limited
Distal positioning of m a n d i b u la r teeth on affected side; fre quent lingual occlusion on unaffected side
Hinge and glide
Slight hinge
Limited
M a n di b ul a r teeth buccal to maxillary on unaffected side (c r o ss b i t e )
H ing e and glide
Hinge or hinge and glide
Distal positioning of ma n d i b u la r teeth on affected side; fr equent lingual occlusion on unaffected side
Hinge and glide
Hinge ancT glide
Retropositioning of m a n d i b u la r teeth
Hinge and glide
Hinge and glide
Relatively normal
Relatively normal
Relatively no rma l
* From S ar n at , B. G. ( e d ) . T h e t e m p o r o m a n d ib u l a r joint, ed 2. Spr ingfield , Ml. Cha rle s C T h o m a s , 1 9 6 4 , pp 1 9 8 - 1 9 9 .
Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 109
COSTOCHONDRAL JUNCTION | CONDYLE O F RIB
OF
MANDIBLE
SYNCHONDROSIS AT OF SKULL
BASE
Fig 3 ■ D iagram m atic representation of variatio n s in tissue arrangem ent adjacent to sites of endo chondral bone fo rm a tio n in rib, m an d ib u la r condyle, a long bone, and a cran ia l synchondrosis, a: zone o f ossifica tio n ; b: zone of h yp ertrophic ca rtilag e ; c: germ inal area and zone o f p ro life ra tin g ca rtilag e (area of endochondral bone fo rm a tio n is the same in all instances); d: zone o f resting c a rti lage cells; e: degenerating cartilage w ith c a lcifie d m atrix; f: chondrogenic zone; g: fib ro u s connec tiv e tissue; h; bone and m arrow of epiphysis; i; a rtic u la r cartilage. Arrangem ent of tissues a pproxi m atin g areas of endochondral bone fo rm a tio n varies in each example. Note in p a rtic u la r th a t there is bone on e ith e r side o f growth ca rtilag e in the long bone (epiphysis). In contrast, th e re is bone on one side and fib ro u s tissue on o ther side o f growth cartilage of m andibular condyle.
Underdevelopment Any disturbance of the condylar cartilage (see list) that will decrease its growth activity will result in underdevelopment of the mandible (Fig 4, 5). The subsequent deformity of the jaws and face is determined not only by the severity and duration of the noxious agent, but also by the particular time of occurrence. Thus, the effect will be more decided if the disturbance occurs early in life when condylar growth activity is greater, than if it oc curs later in life when activity is decreased and the adult m andibular shape and size have been assumed. Unilateral disorders of the condyle usually re sult from local conditions although, occasionally, they may result from some type of systemic in volvement (Fig 4). Bilateral disturbances of the condyle also may result from local causes such as fractured displaced condyloid processes, but prin 110 ■ JADA, Vol. 79, July 1969
cipally they are caused by some systemic con dition (Fig 5). The characteristic clinical and radiographic ob servations on the human m andible after an arrest of growth of one condyle are: ■ on the side of injury, a short, wide condyloid process and ramus, in a more anterior position than its opposite; a relatively longer, heavier, and posteriorly directed coronoid process; a shallow sigmoid notch; a short body; a decided antegonial notch; unerupted and impacted molars; and full ness of the face; ■ on the opposite, uninjured side, elongation of the body of the mandible and a flat appearance of the face; ■ malocclusion of the teeth with the mandible skewed toward the side of the affected condyle (Fig 4D, E). With a bilateral condylar growth arrest there is usually a symmetrical lack of growth of the man-
Causes of underdevelopm ent of tem porom andibular jo in t and m andible* U nilate ral P renatal grow th distu rban ce: c on dylar hypoplasia o r aplasia Postnatal grow th disturbance Traum a Infection R adiation Id io p a th ic: progressive he m ifacial atrophy B ila tera l P renatal grow th distu rban ce H ereditary C hrom osom al anom alies E dw ard’s syndrom e (trisom y 18) T rip lo id y syndrom e T u rn e r’s syndrom e A chondroplasia N anocephalic dw arfism M a ndib u lo fa cia l dysostosis O culom andibulodyscephaly Progeria H anh art’s syndrom e Larsen’s syndrom e U llric h -F e ic h tig e r syndrom e N onhereditary Robin syndrom e M oebius’ syndrom e A rthrom yodysplasia congenita R adiation of fe tu s Postnatal grow th disturbance Endocrine H ypothyroidism H y p o p itu ita ris m D ietary de ficie ncy: v ita m in D Id io p a th ic: rh eum a toid a rth ritis *From Sarnat, B.G., and Laskin, D.M. The tem porom an dibu la r jo in t. In Zegarelli, E.V., and Kutscher, A.H. Diagnosis of d is eases of th e m outh. P hilade lphia, Lea & Febiger, in press.
dible (micrognathia) with the chin retruded to about the level of the hyoid bone (Fig 5 E, F). Bilateral antegonial notching is present. Clinically, patients with condylar growth arrest and retarded mandibular development may have disturbances in the eruption and the position of teeth, particularly in the region of the affected ramus. This is true for at least two reasons. First, the m andibular ramus does not increase in height sufficiently to open the space between the upper and lower jaw s into which the teeth erupt with concomitant growth of the alveolar processes. Second, posterior growth of the ramus is affected, so that length of the body of the mandible is di minished and the last molars are left within the ramus. It is well known that tooth eruption de pends considerably on the growth of the mandible.
Local causes Any local interference (such as trauma, infection, or radiation) which affects the condylar growth center will alter the orderly progression of devel opment and result in some type of TM J and m an dibular deformity (Fig 4C, E). These conditions
Fig 4 ■ U nila te ra l underdevelopm ent of m andible and face arranged in approxim ate chro n o lo g ic order of occurrence. In some instances (C, D, E) m an d ib u la r condyle was involved p rim a rily. In other instances (A, B, F) condyle was involved secondarily. A: This p a tie nt was born w ith external ear and a u d itory canal absent. There was lesser developm ent of con dyle and m andible on affected side and m acrostom ia. B: U nderdevelopm ent of rig h t side of m andible and face sec ondary to shorter rig h t sternom astoid m uscle (to rtic o llis , wryneck). A lthough to rtic o llis may be noted a t b irth , fa cia l d e form ity may not become m an ife st u n til many m onths later. Increased pressure on the condylar growth center, because of sh o rt sternom astoid muscle, is one explanation given fo r growth arrest. C: R ight m an d ib u la r condyle was resected in g row ing m onkey several m onths before death. Note asym m etry, lesser developm ent in both h e ig h t and w id th o f rig ht side of face, and lower p o sition of rig h t external ear. TMJ area on rig ht side fa ile d to develop norm ally. D: Growth arrest and ankylosis of rig h t TMJ in human s ku ll. E: Growth arrest and ankylosis o f rig h t side of m andible as a result of system ic in fe ctio n which spread from h u m e ru sto T M J d u ring infancy. F: Hem ifacial atrophy; th is may not be c lin ic a lly apparent u n til second decade of life ; so ft and hard tissues are affected; etiology is unknown. Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 111
of the jaw. Although some degree of facial paraly sis may be noted at the time of injury, the skeletal deformity is not usually discovered until months afterward. Later in life, direct traum a to the joint or indirect traum a from a blow to the chin, with or without a condylar fracture, also may result in an altered TM J and underdeveloped mandible, provided that the injury occurs during the growth period. ■ Infection: Inflammation on an infectious basis is another cause of changes in the TM J and under development of the mandible. Primary infection of the condylar cartilage is uncommon. M ore fre quent is the spread of regional infection to this region. In the past, otitis media as a result of an upper respiratory infection or scarlet fever, was a frequent antecedent to suppuration of the tem porom andibular region (Fig 5C, D). Since the ad vent of antibiotics, this complication is seldom seen. Growth arrest may also be secondary to a dental infection with spread to the regional tissues and the joint. Hematogenous spread of infection from distant regions also can involve the TM J. F or example, the organisms responsible for osteo myelitis in a long bone may pass to the jaw joint and set up a new focus with resulting growth a r rest and ankylosis (Fig 4E). Prim ary osteomyelitis of the TM J is rare.
Fig 5 ■ B ilateral underdevelopm ent of m andible arranged in approxim ate chro n o lo g ic order o f occurrence. A: Prenatal m an d ib u la r m icrognathia (Robin syndrome). B: Probable prenatal fa cia l diplegia w ith underdevelopm ent of m andible. There is b ila te ra l fa cia l m uscle weakness and m asklike fa c ia l appearance. C and D: Photograph and radiograph of p a tie n t who had sca rlet fever as an in fa n t and b ila te ra l o titis m edia th a t spread to both TMJs a ffe ctin g the condylar c a rti laginous growth centers. Note relatively norm al-sized m axil la and d e fin ite ly underdeveloped m andible. E and F: Photo graph and radiograph o f p a tie n t showing e ffe cts of b ila te ra l condylar growth arrest from rheum atoid a rth ritis . End re s u lt was predicted when p a tie n t was fir s t seen more than ten years earlier.
should be differentiated from hemifacial atrophy in which both bony and soft tissues regress on pos sibly a neurotrophic or traumatic basis (Fig 4F). ■ Trauma: Growth arrest and deformity of the facial skeleton may result from birth traum a (for ceps or breech deliveries) directly to the TMJ region or indirectly transmitted from another part 112 ■ JADA, Vol. 79, July 1969
■ Radiation: Radiation therapy of tumors in the region of the growing condyle not only may destroy the tum or but also affect the condylar growth center and the TM J. This may result in a growth arrest, an asymmetrical mandible, and ankylosis. The radiation-damaged bony tissue may be subject to osteomyelitis and sequestration and the soft tissue to dermatitis and, after 10 or 15 years, carcinoma of the skin.
Systemic causes Hereditary conditions: In achondroplasia, there is a dysfunction of cartilage characterized by a failure to contribute the normal amount of growth. The result is a dwarf with short limbs and lack of development, particularly of the middle third of the face, with concomitant deep saddling of the nose, relative bulging of the forehead, and a relative mandibular prognathism. Since the im portant growth center of the mandible, the condyle, also contains cartilage, the last finding seems para doxical. Apparently cartilage formation in the m
condyle of the mandible is affected to a lesser de gree than in those centers at the base of the skull. This may be due to the fact that in the condyle the new cartilage cells are formed from the connective tissue covering more or less as they are in the perichondrium. In the cranial synchondroses or in an epiphyseal cartilage plate, the new cells form from the cartilage itself. This function is impaired in achondroplasia. ■ Prenatal conditions: Mandibular micrognathia (Robin syndrome, Fig 5A), a prenatal anomaly of unknown etiology, is associated with cleft pal ate, glossoptosis, inspiratory retraction of the sternum, cyanosis, and malnutrition. In many in stances, the postnatal increment of mandibular growth, as related to total facial growth, is suffi cient to overcome the extreme lack of develop ment of the chin that is observed at birth. The glossoptosis is lessened, and spontaneous resolu tion of the respiratory and feeding problems re sults. During this period, however, it may be neces sary to maintain the tongue in an anterior position by suturing it to the lower lip. Micrognathia also occurs in offspring whose mothers, while pregnant, received pelvic X-ray irradiation. Microcephalus, microphthalmia, and deficiency in the dentition may be associated with this. Various other prenatal anomalies of the TMJ and related structures have been reported. These are usually unilateral but may sometimes be bi lateral. A number of facial structures also may be affected in various combinations. In addition, as sociated anomalies are frequently found in other parts of the body. Some of the findings range from underdevelopment of only the condyle to under development of an entire side of the face. The ar ticular fossa, the eminence, the condyloid and coronoid processes, the lower ramus, and part or even all of the mandibular body (and teeth) may be rudimentary or absent. Associated with this may be macrostomia. The external ear may be abnormal in configuration, size, and position, and partially or totally absent (Fig 4A). The external opening of the auditory canal is sometimes unex posed, and the canal, middle and inner ears, tem poral bone, zygoma, and maxilla may be deficient. The etiology may be genetic or environmental and the deformity is related to maldevelopment of the first and second branchial arches. ■ Inflammatory lesions: Rheumatoid arthritis is a cause of inflammation that results in mandibular
underdevelopment (Fig 5E, F). The TMJ is at times the first to manifest clinical symptoms of this disease. The proliferation of cartilage in the condyle is inhibited in much the same manner as in joints elsewhere in the body. Systemic infections can also affect the TMJ and result in growth retardation or arrest. These in clude gonorrhea, syphilis, tuberculosis, typhoid fever, dysentery, pneumonia, influenza, scarlet fever, and measles. Instances of this, however, are quite rare. ■ Dietary deficiencies: Because a lack of vita min D has a systemic effect, the manifestations seen in the condylar cartilage region are only part of the total picture. Other cartilaginous growth centers also are affected. In rachitic children the reduced cartilaginous growth not only produces a shortness of the extremities, but also results in a definite facial disharmony. Delayed eruption and malpositioning of the teeth occur because the intermaxillary space required for eruption is de creased as a result of the shorter ramus. In addition, the anterior border of the ramus fails to resorb at the time the teeth are about to erupt. ■ Endocrine disturbances: Both hypothyroidism and hypopituitarism can affect the growing man dible as well as other parts of the skeleton. The severe results of hypothyroidism are manifest in understature and disproportion. Studies of cretins reveal a generalized retardation of growth within the facial area, and a relatively larger cranial skeleton. The teeth are retarded in development and in eruption, but their size is not affected. Therefore, the teeth and the alveolar processes seem overly large for the smaller body of the max illa and mandible. In hypopituitarism facial growth is decreased proportionately so that the jaws, though small, are in proper relationship.
Ankylosis and facial underdevelopment Ankylosis of the TMJ and facial underdevelop ment frequently occur together (Fig 4D, E). The deformity is believed mistakenly to be a result of the ankylosis. Actually, both could be caused by the same etiologic agent. Thus, a child may have had a middle ear infection which spread to the TMJ and affected it as well as the condylar growth center. Whereas the ankylosis is manifest early, the growth deformity is not apparent until later. In patients who are almost completely unable Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 113
to open the mouth, as in a false or extra-articular ankylosis, and whose condylar growth has not been affected, there is no deformity. In addition, if the TMJ has been affected on only one side with condylar growth arrest and ankylosis, comparable findings are not seen on the opposite side of the jaw which has restricted motion but no growth arrest. The condyle plays a vital role in mandibular and facial growth. Before this important growth center is damaged or removed in children, due consideration should be given to the serious de formity which must result. Thus, in ankylosis of the TMJ, it may be desirable to postpone resec tion of the condyle until maximal mandibular growth has been attained. The degree to which the growth center of the condyle has been affected can be determined by taking serial cephalometric radiographs at 6- to 12-month intervals. If the study indicates that growth is continuing, post ponement of surgical intervention should be con sidered to avoid an even more severe growth ar rest. This need not constitute a similar problem in the adult.
Treatment: general considerations Functional and cosmetic treatment of growth de ficiencies of the TMJ and related areas is difficult; the dysplastic pattern of growth continues. In uni lateral disturbances the discrepancy between the two sides of the face becomes greater with increase in age because of lack of growth of the affected side. Even though the deformity may not be pro gressive, it is not self-correcting and there is no way to compensate for the lost or retarded growth. Orthodontic, prosthetic, and surgical procedures give functional and cosmetic improvement. The surgical procedures commonly used in uni lateral deformities are directed toward contributing bulk and increasing length by means of bone, cartilage, and soft tissue grafts and flaps. Osteot omy, ostectomy, and condylectomy have been performed. Micrognathia has been treated by a sliding osteotomy in the body or ramus, or by a vertical osteotomy in the body with a bone graft. Bone, cartilage, or alloplastic materials have been used as a masking procedure to build up the flat side in asymmetry when one condyle has been af fected or to build up the mental area when there has been a symmetrical arrest. Transplantation of either a metatarsal or a rib-cartilage bone graft with an actively growing endochondral site has 114 ■ JADA, Vol. 79, July 1969
been done as a replacement for the lost or dam aged growth center. Certain aspects of treatment may be undertaken when the patient is still growing but the final re sult cannot be attained until growth of the face has ceased. The associated deformities, such as partially or totally absent ears, can be alleviated by use of cartilage, skin grafts and flaps, or prostheses. The facial weakness is made less conspicu ous after strips of autogenous fascia are inserted subcutaneously and attached near the midline of the face and posteriorly to the temporal muscle.
Overdevelopment
Causes of overdevelopment of the TMJ and the mandible are shown in the accompanying list. Causes of overdevelopment of temporomandibular joint and mandible.* Unilateral Developmental Condylar hyperplasia Hemifacial hypertrophy Neoplastic Fibrous dysplasia Chondroma, osteochondroma, or osteoma of condyle Bilateral Hereditary Klinefelter’s syndrome Angiokeratoma corporis diffusum syndrome Developmental true prognathism Endocrine Giantism Acromegaly *From Sarnat, B.G., and Laskin, D.M. The temporomandibu lar joint. In Zegarelli, E.V., and Kutscher, A.H. Diagnosis of dis eases of the mouth. Philadelphia, Lea & Febiger, in press.
Local conditions m Unilateral hyperplasia o f the mandibular con dyle: This condition is characterized by a slow ly developing distortion and enlargement of the TMJ, a progressive unilateral enlargement of the mandible, facial asymmetry, and shifting of the midline of the chin to the unaffected side with re sulting crossbite malocclusion (Fig 6C-F). The ramus and the body of the affected side of the man dible are longer and larger than the opposite side. Concomitant with increased downward growth of the mandible, which carries the teeth with it, there is a compensatory eruption of the maxillary teeth and downward growth of the maxillary al veolar bone in an attempt to maintain occlusion.
The discrepancy between the two sides of the mandible usually becomes apparent during the second decade of life. For unknown reasons, one condylar growth center becomes more active than the other. Enlargem ent of the condyle has been related to abnormally rapid chondrogenesis with subsequent ossification. Since the histological pic ture is relatively normal and the condition is selflimiting, it is thus not truly a neoplastic process. A histologic diagnosis of chondroma or osteo chondroma is made during the period when growth is still active or osteoma after growth has ceased. The timing of surgical treatment is a most im portant consideration. In children, for instance, if the hyperactive condylar growth center is removed or arrested, the once larger side of the mandible may eventually fall behind the growing side which has not been treated.
■ Prognathic mandible: The prognathic m an dible is larger and in a more forward position than the maxilla, so that the chin appears to be unduly prom inent (Fig 7A, B). In addition, the normal intermaxillary relationship between the teeth is disturbed, so that the m andibular teeth are more anterior to the comparable ones in the maxilla. While there may be considerable m or phologic variation within the group of prognathic mandibles, these are common features: the m an dibular angle tends to be more obtuse; the sig moid notch forms the arc of a larger circle; the condyle and TMJ are not enlarged; the m andibu lar neck is longer and relatively narrower; the linear distance between the superior aspect of the condyle and gnathion (lowest anterior point on the chin) is greater than in the normal man dible; and because of the unusual length of the m andibular body, impaction of molars does not occur. Less frequently seen in a unilateral m andib ular prognathism with a crossbite malocclusion (Fig 6B). Etiology: No definite etiologic factors have been implicated in true mandibular prognathism. It is possible that it may be a genetic problem that is present at birth and proceeds to unfold with growth.
Differential diagnosis: Other conditions that give the appearance of m andibular prognathism must be differentiated from the true type of prognathism previously mentioned. Pituitary dysfunction (giant-
Fig 6 ■ U nilateral overdevelopm ent of m andible and face arranged in approxim ate chro n o lo g ic order o f occurrence. A: Prenatal hem ifacial hypertrophy. E ntire rig h t side of face in clu d in g TMJ was involved. B: U nila te ra l overgrowth of rig h t side of m andible w ith o u t c lin ic a l or radiographic evi dence o f condylar enlargem ent. C and D: Preoperative photo graph and radiograph of p a tie n t w ith le ft condylar hyper plasia, (CH). Note th a t w ith teeth in occlusion m id lin e of ch in is sh ifte d to p a tie nt's right. D and E: Postoperative photograph and radiograph o f same p a tie n t in C and D a fte r resection o f le ft condylar enlargem ent and rep o sitioning of m andible.
ism, acromegaly) leads to an overgrowth and char acteristic prognathism. The normal-sized lower jaw may appear prom inent because of a forward shift due to malposed teeth. Bilateral chronic an terior dislocation also gives the appearance of prognathism (Fig 7E, F). In another group, the mandible is relatively prom inent in comparison with an underdeveloped maxilla, as in certain patients with a cleft palate or achondroplasia. Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 115
an underdeveloped mandible may appear some years later. Therefore, such surgical procedures should be postponed until the child has attained, or nearly attained, adulthood. Patients with sys temic conditions causing mandibular prognathism, as in hyperpituitary disturbances, should not be treated for this local problem without full consid eration of the larger problem.
Systemic conditions • Prenatal hemifacial hypertrophy: In various conditions there is unilateral enlargement of the facial bones including the TMJ. One of these is prenatal hemifacial hypertrophy (Fig 6A). Some times other parts of the body are involved. A l though this condition is present at birth, the dif ferences in size become more accentuated with growth. Not only the TM J, facial bones, jaws and teeth, but also the soft structures including the tongue, palate, and ear are enlarged on one side. The enlarged teeth help differentiate this from other deformities of mandibular overgrowth in which tooth size is unchanged.
Fig 7 ■ A and B: Preoperative photograph and radiograph of p a tie n t w ith decided bilateral m andibular prognathism of unknow n etiology. C and D: Postoperative photograph and radiograph o f same p a tie n t in A and B a fte r b ila te ra l subcondylar osteotom y and retro p o sitio ning o f m andible. E and F: Photograph and radiograph of p a tie n t w ith ch ro n ic b ila t eral u n re ducible a n te rio r dislocation of m andibular condyles w ith changes in TMJs. T his co n d itio n, as w ell as acrom eg aly and others, m ust be considered in d iffe re n tia l diagnosis of p ro m in e n t m andible. Arrow indicates a rtic u la r eminence.
Surgical considerations: Recurrence of prognathism may appear because of continued growth at the condyle when individuals not past their teens are treated by means of either osteotomy of the ramus or ostectomy of part of the m andibular body. C on versely, if the condylar growth centers o f the m an dible are disturbed by surgical treatment and max illary growth continues, an opposite deformity of 116 ■ JADA, Vol. 79, Ju ly 1969
■ Endocrine disturbances— giantism and acromeg aly: Overactivity of the eosinophilic cells of the anterior lobe of the pituitary gland may affect the condylar growth center and the growth of the jaws to a notable degree. This is well illustrated in giantism and acromegaly. In giantism, before the epiphyses have closed there is a proportionate overdevelopment of the osseous system with a massiveness and protrusion of the mandible. There is a definite disproportion between the size of the crowns of the teeth, which show no enlargement, and the large size of the jawbones. In contrast with giantism or hyperpituitarism of adolescence, acromegaly or hyperpituitarism of the adult is characterized by the development of evident disharmonies of the body. Statural growth is not affected because the onset of the disease be gins after the epiphyses have closed. The skeleton however, shows increased density and over growth of osteophytic prominences caused by sub periosteal bone deposition. The central feature of the acromegalic changes in the skull is the enormous enlargement of the mandible. This is due to the latent epiphyseal-like growth potential of the m andibular condyle. A l though growth hormone stimulates periosteal ap-
positional growth of the other facial bones, this growth does not keep pace with the excessive endochondral condylar growth. Consequently the mandible grows out of proportion to the maxilla. The tongue also becomes greatly enlarged and may be responsible for compensatory bone apposi tion along the anterior border of the mandible.
Summary and conclusions The mandibular condyle, an integral part of the TMJ, contains an important epiphyseal-like growth center. Prenatal, postnatal, local, or sys temic conditions, which either stimulate or depress the activity of this zone, may cause over- or under development of the mandible and related struc tures. The degree of the subsequent deformity will depend not only on the type, intensity, ex tent, and chronology of the noxious agent but also on the particular susceptibility and growth activity of the center. In addition, factors that influence apposition and resorption of bone further modify the growth pattern of the TMJ and face. Although some facial abnormalities reflect alter ations in growth primarily of the mandibular con dyle, there are other abnormalities in which con dylar changes are secondary and only part of a larger involvement of the face and sometimes of other parts of the body. An appreciation of normal and abnormal growth is an aid in the early recog nition and proper treatment of developmental de formities of the face and TMJ. A great deal has been learned about the pre natal and postnatal etiology of facial and other abnormalities. During the past decade great strides have been made in deciphering the genetic code. Some aberrations of growth which were believed to have a hereditary basis are now known to be the result of teratogenic agents. These exciting, fas cinating, and rapidly developing fields of study have much to offer. Another interesting factor to consider is the ef fect of our external environment—for example, variations in gravity on the growth centers, and the resulting changes in size and shape of jaws, face, and body. On earth, gravity is considered
normal or 1.OG. What skeletal and other changes will occur in environments of hypogravity (Moon, 0.18G) or hypergravity (Jupiter, 2.65G)? As yet, relatively little information is available.
This report was supported in pa rt by research g ra n t HD 0 0179 from the National In s titu te of C hild Health and H u man Development, US Public Health Service. Doctor Sarnat is a tte nd in g p lastic surgeon, departm ent of surgery, Cedars-Sinai M edical Center and Research In s ti tu te , Los Angeles, and 435 N Roxbury Dr, Beverly H ills, C a lif 90210. He was fo rm e rly professor and head of th e de p a rtm e n t of oral and m axillo facial surgery, College o f Den tis try , and c lin ic a l a ssistant professor o f p la stic surgery, College of M edicine, U niversity o f Illin o is, Chicago. The fo llo w in g illu s tra tio n s have been obtained from o ther sources. Fig 1 from Robinson, I.B., and Sarnat, B.G. Growth pattern o f the pig m andible: a serial roentgenographic study using m e ta llic im plants. Am er J Anat 96:37 Jan 1955; Fig 2 from Sarnat, B.G.; Brodie, A.G.; and Kubacki, W.H. A 14year report o f fa cia l grow th in case of com plete anodontia w ith ectoderm al dysplasia. Am er J Dis C hild 86:162 Aug 1953; Fig 3 from Roy, E.W., and Sarnat, B.G. Growth in length of rabbit ribs a t the costochondral ju n ctio n . Surg Gynec O bstet 103:481 Oct 1956; Fig 4A; 5E,F; 6C, D, E, F; and 7 from Sarnat, B.G., editor, The tem porom andibular jo in t, ed. 2. S p ringfield, Charles C Thomas, 1964; F ig 4 B , E; 6A, B from Sarnat, B.G., and Robinson, I.B. Surgery of the m andible: Some c lin ic a l and experim ental considerations. Plast and Reconst Surg 17:27 Jan 1956; Fig 4D courtesy o f Dr. E. Lloyd DuBrul. Fig 5A, B, C, D from Sarnat, B.G. De velopm ental fa cia l abnorm alities and th e tem porom andibu lar jo in t. Dent Clin N Am er Nov 1966.
1. Brash, J.C.; McKeag, H.; and Scott, J.H. Aetiology o f irre g u la rity and m alocclusion o f th e teeth, ed 2. London, Dental Board o f the U nited Kingdom , 1956. 2. Farmer, E.D., and Lawton, F.E. Stones’ oral and dental diseases, ed 5. Edinburgh, E. & S. Livingstone, Ltd., 1966. 3. Gorlin, R.J., and Pindborg, J.J. Syndromes o f the head and neck. New York, M cG raw-Hill Book Co., 1964. 4. Sarnat, B.G. Facial and neurocranial growth a fte r re moval of the m andibular condyle in the Macaca rhesus m on key. Am er J Surg 94:19 July 1957. 5. Sarnat, B.G. (ed.) The tem porom andibular jo in t, ed 2. S p rin g fie ld , III, Charles C Thomas, 1964. 6. Sarnat, B.G., and Robinson, I.B. Surgery of the m an dible: some c lin ic a l and experim ental considerations. Plast Reconstr Surg 17:27 Jan 1956. 7. Thoma, K.H., and Goldman, H.M. Oral pathology, ed 5. St. Louis, C. V. Mosby Co., 1960. 8. W einm ann, J.P., and Sicher, H. Bone and bones, ed 2. St. Louis, C. V. Mosby Co., 1955. 9. W orth, H.M. (ed.) Principles and practice of oral radio logic in te rp re tatio n . Chicago, Year Book Medical Publishers Inc., 1963.
I
Sarnat: FACIAL ABNORMALITIES AND TMJ a 117
Bernard G. Sarnat,
MD, DDS, Beverly Hills, Calif
Eruption of the teeth and normal development of the mandible as well as some portions of the upper jaw and face are related to function of the growth center in the mandibular condyle. Abnormalities may occur when the activities of this center are either stimulated or depressed by disease or injury. Factors influencing apposition and resorption of bone further modify the growth pattern of the TMJ and face.
The dynamics of the growth of bones are compli cated. Although the basic blueprint of a bone is inherent, the form and architecture may be modi fied during prenatal and postnatal growth by lo cal and systemic influences acting upon various
GROW TH 8 Weeks
FftTTERN OF PIG
16 Weeks
CONTROL
M A N D IB L E I
I 2 0 Weeks
Fig 1 ■ Serial tracings of lateral cephalom etric radiographs of m andible of grow ing pig superposed on o u tlin e s o f fo u r radiopaque im plants. Note superior and posterior d irection and am ount of growth in region o f condyle and posterior border o f ramus. See Fig 2.
108
growth centers and sites. The end result at any given tim e is a record of the effects of all the vicis situdes. The group of bones comprising the tem porom andibular joint and face is no exception. A n integral part of the TM J, the mandibular condyle, bears a site o f endochondral bone forma tion, the condylar cartilage. Appositional growth of this portion of the condyle contributes directly to the increase of mandibular height and length, and indirectly to eruption of the teeth and devel opment of portions of the upper jaw and face. Growth of the condyle and ramus is in a superior and posterior direction (Fig 1). Because o f the articulation of the condyle in the mandibular fos sa, the mandible moves downward and forward (Fig 2). The cartilage in the head of the mandible
Fig 2 ■ Superposed tracings o f lateral cephalom etric radio graphs o f norm al human co n tro l at 5 years 5 m onths, 10 years 5 m onths, and 15 years 7 m onths. A lthough condyle and ramus grow superiorly and posteriorly, m andible a ctually moves downward and forw ard because of a rticu la tio n of condyle in m andibular fossa. See Fig 1.
bances of the condyle and related structures. They range from under- or overdevelopment of only one condyle to under- or overdevelopment of the entire face. All of these conditions can result in facial, as well as occlusal, disharmonies. Any al teration in the size and shape of the condyloid process affects the TMJ. Since the mandible is a single bone, change in one joint will be reflected in the opposite one. In some instances of a general disturbance, changes in the TMJ are only part of the total effect. The resulting malfunctions of the TMJs are manifested by a number of clinical signs (Table). This report is not meant to be all-inclusive but rather to present selected material which can serve as a basis for further study. For additional and de tailed information, other sources are available.1-9
is homologous neither to an epiphyseal cartilage, because it is not interposed between two bony parts, nor to articular cartilage, because the con dylar surface is covered by fibrous tissue. The con dylar cartilage is, however, homologous to that in the head of the clavicle. The histologic arrange ment of tissues is not the same at all centers of endochondral bone growth (Fig 3). On the basis of this difference, certain clinical problems can be explained.
Facial abnormalities and condylar growth activity There are many causes for the various unilateral (Fig 4, 6) and bilateral (Fig 5, 7) growth distur
Table ■ P o s itio n o f m id lin e of ch in a n d o th e r c lin ic a l fin d in g s in d iffe re n tia l d ia g n o s is o f te m p o ro m a n d ib u la r jo in t c o n d itio n s . Midline of chin
C o n d y la r motion
Con dition
Mouth closed
Mouth open
N o r m al
No deviation
No deviation
None
A n t er io r dislocation (u nilateral)
Deviation to unaffected side
Deviation is dec reased
P r om in e n ce of chin on the side unaffected
M a n di b ul a r teeth buccal to maxillary on unaffected side
An te ri or dislocation ( b il at e ra l)
No deviation
No deviation
S ym m e tr ic al p ro m in e nc e of chin
P r em a t ur e m ol ar contact a n d anteriorly op ene d bite
No deviation
Deviation to affected side
May have swelling in associated areas of t ra u m a or fracture
Un u su a lly un c ha nge d
No deviation
No deviation
Retropositioning of mand ible
P r em a t ur e mo la r contact a nd anteriorly opened bite
No deviation
Deviation to affected side
None
Us ually un c ha nge d
Unaffected side flat; chin a pp ea rs p ro m i n e n t on affected side
Fracture d dislocated condyloid process (u n i la t e r a l) Fracture d dislocated condyloid process (b il a t e r a l) Partial ankylosis without gro wt h a rre st ( un ilateral) Partial ankylosis with growth arrest (u n i la t e r a l)
T u m o r of condyle
Deviation to affected side Deviation to unaffected side
Deviation is increased
Facial de formity
Deviation IS
decreased
G ro w th arre st (u ni la t er a l)
Deviation to affected side
Deviation is increased
Growth arre st (b i la t e r al )
No deviation
No deviation
Chin a p p ea rs p r o m in e nt on unaffected side
Unaffected side flat; chin ap p ea rs p ro m i n e n t on affected side M a r ke d sym me tr ica l u n d e r d e v el op m en t of chin and ma ndi bl e
Occlusion
Unaffected side
Affected side
Degree of op en in g
Normal
H in g e and glide
Hi nge and glide
Norm al
Hi nge and glide
Slight hinge and rotation
Limited b y muscle spas m on affected side
Slight hinge
Ma n d i b le fixed in limited op en position
No ne
Limited
None
Ve r y limited
Hinge and glide
Slight hinge
Limited
Distal positioning of m a n d i b u la r teeth on affected side; fre quent lingual occlusion on unaffected side
Hinge and glide
Slight hinge
Limited
M a n di b ul a r teeth buccal to maxillary on unaffected side (c r o ss b i t e )
H ing e and glide
Hinge or hinge and glide
Distal positioning of ma n d i b u la r teeth on affected side; fr equent lingual occlusion on unaffected side
Hinge and glide
Hinge ancT glide
Retropositioning of m a n d i b u la r teeth
Hinge and glide
Hinge and glide
Relatively normal
Relatively normal
Relatively no rma l
* From S ar n at , B. G. ( e d ) . T h e t e m p o r o m a n d ib u l a r joint, ed 2. Spr ingfield , Ml. Cha rle s C T h o m a s , 1 9 6 4 , pp 1 9 8 - 1 9 9 .
Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 109
COSTOCHONDRAL JUNCTION | CONDYLE O F RIB
OF
MANDIBLE
SYNCHONDROSIS AT OF SKULL
BASE
Fig 3 ■ D iagram m atic representation of variatio n s in tissue arrangem ent adjacent to sites of endo chondral bone fo rm a tio n in rib, m an d ib u la r condyle, a long bone, and a cran ia l synchondrosis, a: zone o f ossifica tio n ; b: zone of h yp ertrophic ca rtilag e ; c: germ inal area and zone o f p ro life ra tin g ca rtilag e (area of endochondral bone fo rm a tio n is the same in all instances); d: zone o f resting c a rti lage cells; e: degenerating cartilage w ith c a lcifie d m atrix; f: chondrogenic zone; g: fib ro u s connec tiv e tissue; h; bone and m arrow of epiphysis; i; a rtic u la r cartilage. Arrangem ent of tissues a pproxi m atin g areas of endochondral bone fo rm a tio n varies in each example. Note in p a rtic u la r th a t there is bone on e ith e r side o f growth ca rtilag e in the long bone (epiphysis). In contrast, th e re is bone on one side and fib ro u s tissue on o ther side o f growth cartilage of m andibular condyle.
Underdevelopment Any disturbance of the condylar cartilage (see list) that will decrease its growth activity will result in underdevelopment of the mandible (Fig 4, 5). The subsequent deformity of the jaws and face is determined not only by the severity and duration of the noxious agent, but also by the particular time of occurrence. Thus, the effect will be more decided if the disturbance occurs early in life when condylar growth activity is greater, than if it oc curs later in life when activity is decreased and the adult m andibular shape and size have been assumed. Unilateral disorders of the condyle usually re sult from local conditions although, occasionally, they may result from some type of systemic in volvement (Fig 4). Bilateral disturbances of the condyle also may result from local causes such as fractured displaced condyloid processes, but prin 110 ■ JADA, Vol. 79, July 1969
cipally they are caused by some systemic con dition (Fig 5). The characteristic clinical and radiographic ob servations on the human m andible after an arrest of growth of one condyle are: ■ on the side of injury, a short, wide condyloid process and ramus, in a more anterior position than its opposite; a relatively longer, heavier, and posteriorly directed coronoid process; a shallow sigmoid notch; a short body; a decided antegonial notch; unerupted and impacted molars; and full ness of the face; ■ on the opposite, uninjured side, elongation of the body of the mandible and a flat appearance of the face; ■ malocclusion of the teeth with the mandible skewed toward the side of the affected condyle (Fig 4D, E). With a bilateral condylar growth arrest there is usually a symmetrical lack of growth of the man-
Causes of underdevelopm ent of tem porom andibular jo in t and m andible* U nilate ral P renatal grow th distu rban ce: c on dylar hypoplasia o r aplasia Postnatal grow th disturbance Traum a Infection R adiation Id io p a th ic: progressive he m ifacial atrophy B ila tera l P renatal grow th distu rban ce H ereditary C hrom osom al anom alies E dw ard’s syndrom e (trisom y 18) T rip lo id y syndrom e T u rn e r’s syndrom e A chondroplasia N anocephalic dw arfism M a ndib u lo fa cia l dysostosis O culom andibulodyscephaly Progeria H anh art’s syndrom e Larsen’s syndrom e U llric h -F e ic h tig e r syndrom e N onhereditary Robin syndrom e M oebius’ syndrom e A rthrom yodysplasia congenita R adiation of fe tu s Postnatal grow th disturbance Endocrine H ypothyroidism H y p o p itu ita ris m D ietary de ficie ncy: v ita m in D Id io p a th ic: rh eum a toid a rth ritis *From Sarnat, B.G., and Laskin, D.M. The tem porom an dibu la r jo in t. In Zegarelli, E.V., and Kutscher, A.H. Diagnosis of d is eases of th e m outh. P hilade lphia, Lea & Febiger, in press.
dible (micrognathia) with the chin retruded to about the level of the hyoid bone (Fig 5 E, F). Bilateral antegonial notching is present. Clinically, patients with condylar growth arrest and retarded mandibular development may have disturbances in the eruption and the position of teeth, particularly in the region of the affected ramus. This is true for at least two reasons. First, the m andibular ramus does not increase in height sufficiently to open the space between the upper and lower jaw s into which the teeth erupt with concomitant growth of the alveolar processes. Second, posterior growth of the ramus is affected, so that length of the body of the mandible is di minished and the last molars are left within the ramus. It is well known that tooth eruption de pends considerably on the growth of the mandible.
Local causes Any local interference (such as trauma, infection, or radiation) which affects the condylar growth center will alter the orderly progression of devel opment and result in some type of TM J and m an dibular deformity (Fig 4C, E). These conditions
Fig 4 ■ U nila te ra l underdevelopm ent of m andible and face arranged in approxim ate chro n o lo g ic order of occurrence. In some instances (C, D, E) m an d ib u la r condyle was involved p rim a rily. In other instances (A, B, F) condyle was involved secondarily. A: This p a tie nt was born w ith external ear and a u d itory canal absent. There was lesser developm ent of con dyle and m andible on affected side and m acrostom ia. B: U nderdevelopm ent of rig h t side of m andible and face sec ondary to shorter rig h t sternom astoid m uscle (to rtic o llis , wryneck). A lthough to rtic o llis may be noted a t b irth , fa cia l d e form ity may not become m an ife st u n til many m onths later. Increased pressure on the condylar growth center, because of sh o rt sternom astoid muscle, is one explanation given fo r growth arrest. C: R ight m an d ib u la r condyle was resected in g row ing m onkey several m onths before death. Note asym m etry, lesser developm ent in both h e ig h t and w id th o f rig ht side of face, and lower p o sition of rig h t external ear. TMJ area on rig ht side fa ile d to develop norm ally. D: Growth arrest and ankylosis of rig h t TMJ in human s ku ll. E: Growth arrest and ankylosis o f rig h t side of m andible as a result of system ic in fe ctio n which spread from h u m e ru sto T M J d u ring infancy. F: Hem ifacial atrophy; th is may not be c lin ic a lly apparent u n til second decade of life ; so ft and hard tissues are affected; etiology is unknown. Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 111
of the jaw. Although some degree of facial paraly sis may be noted at the time of injury, the skeletal deformity is not usually discovered until months afterward. Later in life, direct traum a to the joint or indirect traum a from a blow to the chin, with or without a condylar fracture, also may result in an altered TM J and underdeveloped mandible, provided that the injury occurs during the growth period. ■ Infection: Inflammation on an infectious basis is another cause of changes in the TM J and under development of the mandible. Primary infection of the condylar cartilage is uncommon. M ore fre quent is the spread of regional infection to this region. In the past, otitis media as a result of an upper respiratory infection or scarlet fever, was a frequent antecedent to suppuration of the tem porom andibular region (Fig 5C, D). Since the ad vent of antibiotics, this complication is seldom seen. Growth arrest may also be secondary to a dental infection with spread to the regional tissues and the joint. Hematogenous spread of infection from distant regions also can involve the TM J. F or example, the organisms responsible for osteo myelitis in a long bone may pass to the jaw joint and set up a new focus with resulting growth a r rest and ankylosis (Fig 4E). Prim ary osteomyelitis of the TM J is rare.
Fig 5 ■ B ilateral underdevelopm ent of m andible arranged in approxim ate chro n o lo g ic order o f occurrence. A: Prenatal m an d ib u la r m icrognathia (Robin syndrome). B: Probable prenatal fa cia l diplegia w ith underdevelopm ent of m andible. There is b ila te ra l fa cia l m uscle weakness and m asklike fa c ia l appearance. C and D: Photograph and radiograph of p a tie n t who had sca rlet fever as an in fa n t and b ila te ra l o titis m edia th a t spread to both TMJs a ffe ctin g the condylar c a rti laginous growth centers. Note relatively norm al-sized m axil la and d e fin ite ly underdeveloped m andible. E and F: Photo graph and radiograph o f p a tie n t showing e ffe cts of b ila te ra l condylar growth arrest from rheum atoid a rth ritis . End re s u lt was predicted when p a tie n t was fir s t seen more than ten years earlier.
should be differentiated from hemifacial atrophy in which both bony and soft tissues regress on pos sibly a neurotrophic or traumatic basis (Fig 4F). ■ Trauma: Growth arrest and deformity of the facial skeleton may result from birth traum a (for ceps or breech deliveries) directly to the TMJ region or indirectly transmitted from another part 112 ■ JADA, Vol. 79, July 1969
■ Radiation: Radiation therapy of tumors in the region of the growing condyle not only may destroy the tum or but also affect the condylar growth center and the TM J. This may result in a growth arrest, an asymmetrical mandible, and ankylosis. The radiation-damaged bony tissue may be subject to osteomyelitis and sequestration and the soft tissue to dermatitis and, after 10 or 15 years, carcinoma of the skin.
Systemic causes Hereditary conditions: In achondroplasia, there is a dysfunction of cartilage characterized by a failure to contribute the normal amount of growth. The result is a dwarf with short limbs and lack of development, particularly of the middle third of the face, with concomitant deep saddling of the nose, relative bulging of the forehead, and a relative mandibular prognathism. Since the im portant growth center of the mandible, the condyle, also contains cartilage, the last finding seems para doxical. Apparently cartilage formation in the m
condyle of the mandible is affected to a lesser de gree than in those centers at the base of the skull. This may be due to the fact that in the condyle the new cartilage cells are formed from the connective tissue covering more or less as they are in the perichondrium. In the cranial synchondroses or in an epiphyseal cartilage plate, the new cells form from the cartilage itself. This function is impaired in achondroplasia. ■ Prenatal conditions: Mandibular micrognathia (Robin syndrome, Fig 5A), a prenatal anomaly of unknown etiology, is associated with cleft pal ate, glossoptosis, inspiratory retraction of the sternum, cyanosis, and malnutrition. In many in stances, the postnatal increment of mandibular growth, as related to total facial growth, is suffi cient to overcome the extreme lack of develop ment of the chin that is observed at birth. The glossoptosis is lessened, and spontaneous resolu tion of the respiratory and feeding problems re sults. During this period, however, it may be neces sary to maintain the tongue in an anterior position by suturing it to the lower lip. Micrognathia also occurs in offspring whose mothers, while pregnant, received pelvic X-ray irradiation. Microcephalus, microphthalmia, and deficiency in the dentition may be associated with this. Various other prenatal anomalies of the TMJ and related structures have been reported. These are usually unilateral but may sometimes be bi lateral. A number of facial structures also may be affected in various combinations. In addition, as sociated anomalies are frequently found in other parts of the body. Some of the findings range from underdevelopment of only the condyle to under development of an entire side of the face. The ar ticular fossa, the eminence, the condyloid and coronoid processes, the lower ramus, and part or even all of the mandibular body (and teeth) may be rudimentary or absent. Associated with this may be macrostomia. The external ear may be abnormal in configuration, size, and position, and partially or totally absent (Fig 4A). The external opening of the auditory canal is sometimes unex posed, and the canal, middle and inner ears, tem poral bone, zygoma, and maxilla may be deficient. The etiology may be genetic or environmental and the deformity is related to maldevelopment of the first and second branchial arches. ■ Inflammatory lesions: Rheumatoid arthritis is a cause of inflammation that results in mandibular
underdevelopment (Fig 5E, F). The TMJ is at times the first to manifest clinical symptoms of this disease. The proliferation of cartilage in the condyle is inhibited in much the same manner as in joints elsewhere in the body. Systemic infections can also affect the TMJ and result in growth retardation or arrest. These in clude gonorrhea, syphilis, tuberculosis, typhoid fever, dysentery, pneumonia, influenza, scarlet fever, and measles. Instances of this, however, are quite rare. ■ Dietary deficiencies: Because a lack of vita min D has a systemic effect, the manifestations seen in the condylar cartilage region are only part of the total picture. Other cartilaginous growth centers also are affected. In rachitic children the reduced cartilaginous growth not only produces a shortness of the extremities, but also results in a definite facial disharmony. Delayed eruption and malpositioning of the teeth occur because the intermaxillary space required for eruption is de creased as a result of the shorter ramus. In addition, the anterior border of the ramus fails to resorb at the time the teeth are about to erupt. ■ Endocrine disturbances: Both hypothyroidism and hypopituitarism can affect the growing man dible as well as other parts of the skeleton. The severe results of hypothyroidism are manifest in understature and disproportion. Studies of cretins reveal a generalized retardation of growth within the facial area, and a relatively larger cranial skeleton. The teeth are retarded in development and in eruption, but their size is not affected. Therefore, the teeth and the alveolar processes seem overly large for the smaller body of the max illa and mandible. In hypopituitarism facial growth is decreased proportionately so that the jaws, though small, are in proper relationship.
Ankylosis and facial underdevelopment Ankylosis of the TMJ and facial underdevelop ment frequently occur together (Fig 4D, E). The deformity is believed mistakenly to be a result of the ankylosis. Actually, both could be caused by the same etiologic agent. Thus, a child may have had a middle ear infection which spread to the TMJ and affected it as well as the condylar growth center. Whereas the ankylosis is manifest early, the growth deformity is not apparent until later. In patients who are almost completely unable Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 113
to open the mouth, as in a false or extra-articular ankylosis, and whose condylar growth has not been affected, there is no deformity. In addition, if the TMJ has been affected on only one side with condylar growth arrest and ankylosis, comparable findings are not seen on the opposite side of the jaw which has restricted motion but no growth arrest. The condyle plays a vital role in mandibular and facial growth. Before this important growth center is damaged or removed in children, due consideration should be given to the serious de formity which must result. Thus, in ankylosis of the TMJ, it may be desirable to postpone resec tion of the condyle until maximal mandibular growth has been attained. The degree to which the growth center of the condyle has been affected can be determined by taking serial cephalometric radiographs at 6- to 12-month intervals. If the study indicates that growth is continuing, post ponement of surgical intervention should be con sidered to avoid an even more severe growth ar rest. This need not constitute a similar problem in the adult.
Treatment: general considerations Functional and cosmetic treatment of growth de ficiencies of the TMJ and related areas is difficult; the dysplastic pattern of growth continues. In uni lateral disturbances the discrepancy between the two sides of the face becomes greater with increase in age because of lack of growth of the affected side. Even though the deformity may not be pro gressive, it is not self-correcting and there is no way to compensate for the lost or retarded growth. Orthodontic, prosthetic, and surgical procedures give functional and cosmetic improvement. The surgical procedures commonly used in uni lateral deformities are directed toward contributing bulk and increasing length by means of bone, cartilage, and soft tissue grafts and flaps. Osteot omy, ostectomy, and condylectomy have been performed. Micrognathia has been treated by a sliding osteotomy in the body or ramus, or by a vertical osteotomy in the body with a bone graft. Bone, cartilage, or alloplastic materials have been used as a masking procedure to build up the flat side in asymmetry when one condyle has been af fected or to build up the mental area when there has been a symmetrical arrest. Transplantation of either a metatarsal or a rib-cartilage bone graft with an actively growing endochondral site has 114 ■ JADA, Vol. 79, July 1969
been done as a replacement for the lost or dam aged growth center. Certain aspects of treatment may be undertaken when the patient is still growing but the final re sult cannot be attained until growth of the face has ceased. The associated deformities, such as partially or totally absent ears, can be alleviated by use of cartilage, skin grafts and flaps, or prostheses. The facial weakness is made less conspicu ous after strips of autogenous fascia are inserted subcutaneously and attached near the midline of the face and posteriorly to the temporal muscle.
Overdevelopment
Causes of overdevelopment of the TMJ and the mandible are shown in the accompanying list. Causes of overdevelopment of temporomandibular joint and mandible.* Unilateral Developmental Condylar hyperplasia Hemifacial hypertrophy Neoplastic Fibrous dysplasia Chondroma, osteochondroma, or osteoma of condyle Bilateral Hereditary Klinefelter’s syndrome Angiokeratoma corporis diffusum syndrome Developmental true prognathism Endocrine Giantism Acromegaly *From Sarnat, B.G., and Laskin, D.M. The temporomandibu lar joint. In Zegarelli, E.V., and Kutscher, A.H. Diagnosis of dis eases of the mouth. Philadelphia, Lea & Febiger, in press.
Local conditions m Unilateral hyperplasia o f the mandibular con dyle: This condition is characterized by a slow ly developing distortion and enlargement of the TMJ, a progressive unilateral enlargement of the mandible, facial asymmetry, and shifting of the midline of the chin to the unaffected side with re sulting crossbite malocclusion (Fig 6C-F). The ramus and the body of the affected side of the man dible are longer and larger than the opposite side. Concomitant with increased downward growth of the mandible, which carries the teeth with it, there is a compensatory eruption of the maxillary teeth and downward growth of the maxillary al veolar bone in an attempt to maintain occlusion.
The discrepancy between the two sides of the mandible usually becomes apparent during the second decade of life. For unknown reasons, one condylar growth center becomes more active than the other. Enlargem ent of the condyle has been related to abnormally rapid chondrogenesis with subsequent ossification. Since the histological pic ture is relatively normal and the condition is selflimiting, it is thus not truly a neoplastic process. A histologic diagnosis of chondroma or osteo chondroma is made during the period when growth is still active or osteoma after growth has ceased. The timing of surgical treatment is a most im portant consideration. In children, for instance, if the hyperactive condylar growth center is removed or arrested, the once larger side of the mandible may eventually fall behind the growing side which has not been treated.
■ Prognathic mandible: The prognathic m an dible is larger and in a more forward position than the maxilla, so that the chin appears to be unduly prom inent (Fig 7A, B). In addition, the normal intermaxillary relationship between the teeth is disturbed, so that the m andibular teeth are more anterior to the comparable ones in the maxilla. While there may be considerable m or phologic variation within the group of prognathic mandibles, these are common features: the m an dibular angle tends to be more obtuse; the sig moid notch forms the arc of a larger circle; the condyle and TMJ are not enlarged; the m andibu lar neck is longer and relatively narrower; the linear distance between the superior aspect of the condyle and gnathion (lowest anterior point on the chin) is greater than in the normal man dible; and because of the unusual length of the m andibular body, impaction of molars does not occur. Less frequently seen in a unilateral m andib ular prognathism with a crossbite malocclusion (Fig 6B). Etiology: No definite etiologic factors have been implicated in true mandibular prognathism. It is possible that it may be a genetic problem that is present at birth and proceeds to unfold with growth.
Differential diagnosis: Other conditions that give the appearance of m andibular prognathism must be differentiated from the true type of prognathism previously mentioned. Pituitary dysfunction (giant-
Fig 6 ■ U nilateral overdevelopm ent of m andible and face arranged in approxim ate chro n o lo g ic order o f occurrence. A: Prenatal hem ifacial hypertrophy. E ntire rig h t side of face in clu d in g TMJ was involved. B: U nila te ra l overgrowth of rig h t side of m andible w ith o u t c lin ic a l or radiographic evi dence o f condylar enlargem ent. C and D: Preoperative photo graph and radiograph of p a tie n t w ith le ft condylar hyper plasia, (CH). Note th a t w ith teeth in occlusion m id lin e of ch in is sh ifte d to p a tie nt's right. D and E: Postoperative photograph and radiograph o f same p a tie n t in C and D a fte r resection o f le ft condylar enlargem ent and rep o sitioning of m andible.
ism, acromegaly) leads to an overgrowth and char acteristic prognathism. The normal-sized lower jaw may appear prom inent because of a forward shift due to malposed teeth. Bilateral chronic an terior dislocation also gives the appearance of prognathism (Fig 7E, F). In another group, the mandible is relatively prom inent in comparison with an underdeveloped maxilla, as in certain patients with a cleft palate or achondroplasia. Sarnat: FACIAL ABNORMALITIES AND TMJ ■ 115
an underdeveloped mandible may appear some years later. Therefore, such surgical procedures should be postponed until the child has attained, or nearly attained, adulthood. Patients with sys temic conditions causing mandibular prognathism, as in hyperpituitary disturbances, should not be treated for this local problem without full consid eration of the larger problem.
Systemic conditions • Prenatal hemifacial hypertrophy: In various conditions there is unilateral enlargement of the facial bones including the TMJ. One of these is prenatal hemifacial hypertrophy (Fig 6A). Some times other parts of the body are involved. A l though this condition is present at birth, the dif ferences in size become more accentuated with growth. Not only the TM J, facial bones, jaws and teeth, but also the soft structures including the tongue, palate, and ear are enlarged on one side. The enlarged teeth help differentiate this from other deformities of mandibular overgrowth in which tooth size is unchanged.
Fig 7 ■ A and B: Preoperative photograph and radiograph of p a tie n t w ith decided bilateral m andibular prognathism of unknow n etiology. C and D: Postoperative photograph and radiograph o f same p a tie n t in A and B a fte r b ila te ra l subcondylar osteotom y and retro p o sitio ning o f m andible. E and F: Photograph and radiograph of p a tie n t w ith ch ro n ic b ila t eral u n re ducible a n te rio r dislocation of m andibular condyles w ith changes in TMJs. T his co n d itio n, as w ell as acrom eg aly and others, m ust be considered in d iffe re n tia l diagnosis of p ro m in e n t m andible. Arrow indicates a rtic u la r eminence.
Surgical considerations: Recurrence of prognathism may appear because of continued growth at the condyle when individuals not past their teens are treated by means of either osteotomy of the ramus or ostectomy of part of the m andibular body. C on versely, if the condylar growth centers o f the m an dible are disturbed by surgical treatment and max illary growth continues, an opposite deformity of 116 ■ JADA, Vol. 79, Ju ly 1969
■ Endocrine disturbances— giantism and acromeg aly: Overactivity of the eosinophilic cells of the anterior lobe of the pituitary gland may affect the condylar growth center and the growth of the jaws to a notable degree. This is well illustrated in giantism and acromegaly. In giantism, before the epiphyses have closed there is a proportionate overdevelopment of the osseous system with a massiveness and protrusion of the mandible. There is a definite disproportion between the size of the crowns of the teeth, which show no enlargement, and the large size of the jawbones. In contrast with giantism or hyperpituitarism of adolescence, acromegaly or hyperpituitarism of the adult is characterized by the development of evident disharmonies of the body. Statural growth is not affected because the onset of the disease be gins after the epiphyses have closed. The skeleton however, shows increased density and over growth of osteophytic prominences caused by sub periosteal bone deposition. The central feature of the acromegalic changes in the skull is the enormous enlargement of the mandible. This is due to the latent epiphyseal-like growth potential of the m andibular condyle. A l though growth hormone stimulates periosteal ap-
positional growth of the other facial bones, this growth does not keep pace with the excessive endochondral condylar growth. Consequently the mandible grows out of proportion to the maxilla. The tongue also becomes greatly enlarged and may be responsible for compensatory bone apposi tion along the anterior border of the mandible.
Summary and conclusions The mandibular condyle, an integral part of the TMJ, contains an important epiphyseal-like growth center. Prenatal, postnatal, local, or sys temic conditions, which either stimulate or depress the activity of this zone, may cause over- or under development of the mandible and related struc tures. The degree of the subsequent deformity will depend not only on the type, intensity, ex tent, and chronology of the noxious agent but also on the particular susceptibility and growth activity of the center. In addition, factors that influence apposition and resorption of bone further modify the growth pattern of the TMJ and face. Although some facial abnormalities reflect alter ations in growth primarily of the mandibular con dyle, there are other abnormalities in which con dylar changes are secondary and only part of a larger involvement of the face and sometimes of other parts of the body. An appreciation of normal and abnormal growth is an aid in the early recog nition and proper treatment of developmental de formities of the face and TMJ. A great deal has been learned about the pre natal and postnatal etiology of facial and other abnormalities. During the past decade great strides have been made in deciphering the genetic code. Some aberrations of growth which were believed to have a hereditary basis are now known to be the result of teratogenic agents. These exciting, fas cinating, and rapidly developing fields of study have much to offer. Another interesting factor to consider is the ef fect of our external environment—for example, variations in gravity on the growth centers, and the resulting changes in size and shape of jaws, face, and body. On earth, gravity is considered
normal or 1.OG. What skeletal and other changes will occur in environments of hypogravity (Moon, 0.18G) or hypergravity (Jupiter, 2.65G)? As yet, relatively little information is available.
This report was supported in pa rt by research g ra n t HD 0 0179 from the National In s titu te of C hild Health and H u man Development, US Public Health Service. Doctor Sarnat is a tte nd in g p lastic surgeon, departm ent of surgery, Cedars-Sinai M edical Center and Research In s ti tu te , Los Angeles, and 435 N Roxbury Dr, Beverly H ills, C a lif 90210. He was fo rm e rly professor and head of th e de p a rtm e n t of oral and m axillo facial surgery, College o f Den tis try , and c lin ic a l a ssistant professor o f p la stic surgery, College of M edicine, U niversity o f Illin o is, Chicago. The fo llo w in g illu s tra tio n s have been obtained from o ther sources. Fig 1 from Robinson, I.B., and Sarnat, B.G. Growth pattern o f the pig m andible: a serial roentgenographic study using m e ta llic im plants. Am er J Anat 96:37 Jan 1955; Fig 2 from Sarnat, B.G.; Brodie, A.G.; and Kubacki, W.H. A 14year report o f fa cia l grow th in case of com plete anodontia w ith ectoderm al dysplasia. Am er J Dis C hild 86:162 Aug 1953; Fig 3 from Roy, E.W., and Sarnat, B.G. Growth in length of rabbit ribs a t the costochondral ju n ctio n . Surg Gynec O bstet 103:481 Oct 1956; Fig 4A; 5E,F; 6C, D, E, F; and 7 from Sarnat, B.G., editor, The tem porom andibular jo in t, ed. 2. S p ringfield, Charles C Thomas, 1964; F ig 4 B , E; 6A, B from Sarnat, B.G., and Robinson, I.B. Surgery of the m andible: Some c lin ic a l and experim ental considerations. Plast and Reconst Surg 17:27 Jan 1956; Fig 4D courtesy o f Dr. E. Lloyd DuBrul. Fig 5A, B, C, D from Sarnat, B.G. De velopm ental fa cia l abnorm alities and th e tem porom andibu lar jo in t. Dent Clin N Am er Nov 1966.
1. Brash, J.C.; McKeag, H.; and Scott, J.H. Aetiology o f irre g u la rity and m alocclusion o f th e teeth, ed 2. London, Dental Board o f the U nited Kingdom , 1956. 2. Farmer, E.D., and Lawton, F.E. Stones’ oral and dental diseases, ed 5. Edinburgh, E. & S. Livingstone, Ltd., 1966. 3. Gorlin, R.J., and Pindborg, J.J. Syndromes o f the head and neck. New York, M cG raw-Hill Book Co., 1964. 4. Sarnat, B.G. Facial and neurocranial growth a fte r re moval of the m andibular condyle in the Macaca rhesus m on key. Am er J Surg 94:19 July 1957. 5. Sarnat, B.G. (ed.) The tem porom andibular jo in t, ed 2. S p rin g fie ld , III, Charles C Thomas, 1964. 6. Sarnat, B.G., and Robinson, I.B. Surgery of the m an dible: some c lin ic a l and experim ental considerations. Plast Reconstr Surg 17:27 Jan 1956. 7. Thoma, K.H., and Goldman, H.M. Oral pathology, ed 5. St. Louis, C. V. Mosby Co., 1960. 8. W einm ann, J.P., and Sicher, H. Bone and bones, ed 2. St. Louis, C. V. Mosby Co., 1955. 9. W orth, H.M. (ed.) Principles and practice of oral radio logic in te rp re tatio n . Chicago, Year Book Medical Publishers Inc., 1963.
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