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Clinical implications of the temporomandibular joint
Clinical implications of the temporomandibular joint ROBERT
M.
Palisades,
Pacific
RICKETTR,
D.D.S.,
M.H.”
Calif.
THE orthodontist is expected to possess consummate knowledge of temporomandibular growth, morphology, function, and characteristics. He should be the master of occlusion and functional articulation. The temporomandibular joint, however, continues to cause more controversy and present more inconsistencies than any other structure with which the orthodontist is concerned. Because it is mechanical and connected with the teeth, this joint can be a@ected by traumatic phenomena. As a biologic entity, it serves unique purposes and must be approached scientifically and logically. SCIENTIFIC
INVESTIGATION
AND
THE
TEMPOROMANDIBULAR
JOINT
Any acquired knowledge obtained in a systematic manner might be classified as scientific. One of the most fundamental and primary levels of scientific investigation is that of obtaining descriptive knowledge. An investigator in a,natomy tries to explain the structural nature of his subject. In order to accomplish this technically, it is necessary to measure, and trustworthy methods must be devised by which dimensional deswiptions can be attained. The establishment of ranges of variation in structural anatomy and function is basic and is considered a scientific study. The second task of any investigator is one of logic-of organization, classification, and formulation of hypotheses. It involves the handling or control of protocol facts derived from basic technical procedure. Therefore, verification becomes a di&icult task of the clinician in a clinical science. When I was assigned the subject of “Clinical Implications of the TemporoPresented 12, 1965, *On
416
the
before as part staff
the American Association of of a panel discussion on “The
of the
University
of California
Orthodontists in Temporomandibular
at Los
Angeles.
Dallas, Texas, Joint.”
May
Volume Number
Temporomandibular
52 6
joint
4 17
mandibular Joint” as my part of this panel discussion, I decided to attempt to describe a method, to enumerate pertinent protocol facts, to formulate certain hypotheses, and to present evidence to justify certain conclusions. METHODOLOGY
In 1964, in writing about roentgenographic procedures in the temporomandibular joint,l I concluded that, essentially, two major techniques out of the dozen or so listed had come to use standardized head-holding equipment with controlled x-ray exposures. The two most usable were (1) the transcranial oblique view and (2) the body-section x-ray or laminagraphy, which has been used in the research that I started in 1947. (This technique, also called planigraphy or tomography, should not be confused with pantomyography, which is employed for dental purposes.) Laminagraphy combines cephalometrics with undistorted body sections made at standard enlargements. Duplicated views are obtained with the same accuracy as routine cephalometric roentgenograms. The DOME Xectograph, which I designed, is illustrated in Fig. 1. This technique permits the patient to be seated upright so that standard frontal and lateral or oblique cephalometric roentgenograms can be obtained at a standardized 60 inch patient-target distance. In addition, the tube is set in motion and, at prescribed depths, cuts, layers, or x-ray body sections are obtained as required and at the same size as the cephalograms. In addition to straight lateral joint “cuts,” the head can be turned to a view that is perpendicular to the transverse axis of the condyle. A 20 degree oblique standard view of the temporomandibular joint has come to be employed. One side of the mandible is aligned parallel to the film. The complete buccal occlusion, together with the ramus and joint, is oriented in one plane (Fig. 2). This oblique-view body section yields an excellent portrayal of the upper and lower third molars in addition to the tuberosity, the pterygoid plates, and exceptional deta.il of the joint itself. Laminagraphy of the joint is used in conjunction with frontal and lateral standard cephalometrics. In clinical practice it has come into routine use for all orthodontic cases. Laminagraphy is essential to the diagnosis of pathologic conditions of the joint. Cuts in other planes are pa,rticularly useful in cleft palate dia,gnosis. ROLE
OF THE
TEMPOROMANDIBULAR
JOINT
IN
RELATION
TO
PhTHOLOGIC
CONDITIONS
On numerous occasions I have published findings on normal form and function,2-4 and I find no reason to alter those values. Lindblom,5 using controlled transcranial views and stereoptics, essentially corroborated my findings. However, it may be fruitful to discuss clinical implications in view of this joint’s functions or the total role that it plays. Therefore, three main functions of this joint may be listed: 1. Its role in the act of mouth opening. 2. Its role in dental articulation or functional occlusion.
418
Rick&s
@v,
Fig. 1. I )OME Sectograph for c~ephalometric rocntgenograplly aud i:c,1)II:Llomt,t~il. lamir lagra consi stin g of oriented at p shot, head-holding apparatus, moving caesettc racok, depth indicator overk lead driving rod (above), track for moving x-ray hbc, and rotating anode I ube, centered in illustration at 5 foot distance for routine head films (helow\
Volume Number
Fig.
Temporomanndibular
52 6
2. Lateral
20 degree
oblique
laminagraph.
Note
structures
in focus
in this
joint
4 19
plane.
3. Its growth function and the effects of subsequent degeneration or breakdown that might occur under pathologic conditions. This joint usually can be made to hinge for, roughly, the first half of the normal extent of opening, although the typical patient translates the condyle forward quite early in the act. As a provision for wide mouth-opening without obstruction of the airway by retraction of the chin, the condyle is brought far forward or the head is tilted backward. Limited opening is typical in patients with condyle fractures. Size and shape of the mandible have been shown to be related to the opening and closing movements. By anatomic arrangement, it is the role of the external pterygoid muscle to stabilize, protect, or modify the respiratory airway and provide the mechanism for protruding the mandible during speech. This muscle further helps to control the delicate movements of incision a.nd lateral excursion. The external pterygoid lies almost parallel to the functioning surface of the joint which it must cause to slide. During a slide, a resistance can introduce friction, and pathologic situations appa.rently can be established rather easily. Thus, one of the primary functions of this joint is to provide a mechanism for opening and protrusion of the mandible, and for this a slide is necessary. When this translatory movement cannot be obtained, functional impairment results. The second consideration, in terms of purpose and function of this joint, is its role in relation to articulation of the teeth. I have stated on numerous occaof the teeth. Portions of the dentition sions that this joint is a disarticulator are separated and sections of the arches are brought into functional relationship
420
IZicketts
for a particular activity, instead of all the teeth WCiLYillg against all tllck othc’l teeth all of the t.ime. Under this scheme, thcrc is a conser\ra tzion ot’ II~IIW~I~Y energy, a conservation of tooth tissue, and a beautiful and harmonious pattern in normal occlusion and normal functional art,itulation. During incision the condylo is brought forwa.rd and, with normal joint form and normal overbite, t.he posterior teeth are not, in contact. The condyle, b! moving forward on the eminence, must also move downward. By virtue of this relationship, the posterior teeth are disarticulated. Stresses and wear on the posterior teeth are prevented as fun&ion is directed to the anterior portion of the denture. In lateral excursions, the condyle is brought downward a.nd forward on the eminence on one side only. The ipsilateral condyle rotates. Contact. in t,he cuspid or corner of the elliptical arch form is obtained unila.t.erally. Disarticulation is obtained on a unilateral basis, a.nd forces are still directed at one particular area in the denture, at the curve of the a,rc of the dental arch. This function has been referred to as “cuspid protect.ion” (Fig. 3). The normal pattern of function is cxcrcised in complete muscular harmony. The teeth act as receptors and are closely linked by neurologic reflexes to the muscles and joint. Functional patterns with smoot,h, integrated patterns of muscle coordination are obtained and controlled by the neuromuscular circuit.
Fig. teeth
3. During lateral of that side while
excursion, downward and cuspid contact disarticulates
forward posterior
condyle teeth
movements of Tvorking”
disarticulate side.
Volume Number
52 6
Temporomandibular
joint
42 1
In 1953 I published an analysis of 180 pathologic cases.O A premise was made that temporomandibular joint disease stemmed from problems in functional occlusion. Four distinct types of traumatic joint disturbance seemed to accrue from four different types of clinical malocclusion. The first of these conditions (Type I) was abnormal overjet, characterized by the typical Class II, Division 1 relationship. The patient would move the mandible forward in compensation for the protruding teeth during incision and speech, but the condyle usually was drawn backward to a normal position in the fossa in forced occlusion (although some patients sustain a mesial displacement). An abnormal range of function stresses the joint and thus results in condyle trauma. Type II was identified as true distal thrust or posterior displacement. When the condyle was dislocated backward, it apparently lodged behind the bulbous portion of the articular disc, and clicking or snapping became audible. The inclines of the teeth could cause this type of displa,cement by influencing muscular and ligamentous structures. Another type of problem (Type III) was one of interference phenomenon. Contralateral tooth contact (opposite to the working side) upsets the normal integrated pattern of movement, and traumatic conditions in one or both joints subsequently occur. If the posterior teeth on the left side contact during the mandible’s lateral excursion to the right, trauma is experienced. Normally, the overbite of the cuspids and premolars helps separate the teeth of the opposite side. I concluded that there is no such thing as a so-called balancing side in normal occlusions. On the contrary, when balancing cusps were found, joint pathosis often was present. Type IV was one of loss of posterior support. Although all joints sustain contact, this joint is not designed for heavy weight-bearing and, with the loss of posterior teeth, it may become overstressed. If force becomes continuous, the joint breaks down as a result of excessive pressures of long duration. Degenerative joint disease is progressive and has been shown to result from a single traumatic episode. Continued trauma produces continuous re-injury. When interferences develop in occlusion, the muscle patterns become distorted and function becomes confused. Actual mechanical trauma set up by occlusal interferences will either wear the teeth, loosen the teeth, or jar the joint. Thus, tooth attrition, periodontal breakdown, or traumatic arthritis can develop. Indeed, all three of these conditions can prevail in the same person, although it is possible that only one of them may occur. If the condyle is already forward, or if the eminence is flat, there can be no separation or disarticulation of the posterior teeth. In that case, a situation of wear or trauma on the teeth is set up and severe attrition results. If a small condyle is placed posteriorly in a large fossa, no functional eminence results during the early phase of excursion, although an eminence may actually be present. Because of the la.ck of condyle juxtaposition with the eminence, there is no separation of the posterior teeth. This can be demonstrated by pushing the mandible directly from side to side. In either of these situations, the teeth wear excessively. This is exactly what
Lack of eminence height or absence of a functioning joint also is a factor in clinical diagnosis, for traumatic joint conditions ostensibly can occur even in children. For instance, a patient wit.h a slight Class II malocclusion who also has slight ailway limitat.ions in the pharynx might adapt, to a forward mandibular position. No functional eminence results, particularly in the young, a.nd the condyle may begin to be pathologically t,raumatized. CONDYLE
GROWTH
The overwhelming clinical significance of the temposromandibular joint is related to growth of the mandible. On the basis of my observations, I took the stand that function did not influence mandibular growth.7 This related to the concept of release of pressure by a pulling forward of the condyle out of the confines of a fossa, which did not cause the mandible to grow. Patients in whom this phenomenon was observed did not experience a,n increased amount of growth in the mandible. Distal displacement did not appear to be a growthlimiting factor because of overwhelming growth turgor in the normal healthy child. On the basis of recent evidence, however, it is conceivable (but sheer speculation at this point) that growth can be affected, but because of excessive traumatic function with pathologic regression. Could forward positions of the mandible damage the condyle, influence cartilage growth, and alter mandibular growth and form? Growth should be discussed from the standpoint of (1) normal growth significance of the condyle, (2) results of a biologic interference, and (3) relationships following traumatic interference. For more than a decade, I have described growth of the condyle as it influences the development of the mandible, first, as an explanation of changes during treatment and, second, as a biologic background for prognosis of growth during orthodontic treatment. Variation in growth was described from studies with laminagraph sections through the condyle, ramus, and part of the mandible. It was observed, after superimposing on the lower border of the mandible, that average growth tended to proceed almost directly up the long axis of the condylar head.* The chin allegedly would be directed downward and forward by upward and backward growth of the mandibular condyle. This seemed to be an acceptable description of normal behavior and served at least as a working hypothesis or an explanation of chin behavior. It also wa,s observed however, that not all faces developed in a constantly parallel fashion. Development might follow a generally constant pattern of consistent change toward a longer face (vertical increases). At the opposite extreme, deeper faces or horizontal increases were observed. Thus, dolichofacial (long) patterns or brachyfacial (short, square) characteristics tended to develop in consistent directions, although gradients in growth were not necessarily
V01um.9 Number
52 6
Temporomandibular
joint
423
even. Slight variations were observed, but one distinguished type did not tend to reverse or transpose to another distinguished type. In the distinction of these types, I showed in 1952, that in patients who developed greater facial length mandibles tended to become more obtuse.8 These patients developed higher mandibular plane angles with growth and their condyles grew more posteriorly than straight up the condyle axis. This finding came as a shock; it had always been assumed that a more backward direction of condylar growth would lead to a forward position of the chin, but such was not the case. Backward condylar growth, with obtusely developing mandibles, was observed in patients whose chins were moving downward or downward and backwa,rd, just opposite to the formerly conceived pattern. At the other extreme, those patients dereloping facial squareness (brachyfacial characteristics), with chins that were observed to move straight forward from a cephalometric standpoint, were identified as having preponderantly upward and forward condylar growth. The mandible was growing more in an arc and contributing to a forward swing of the chin. Facial height in this type was not increasing at the sa.me rate as facial depth. Condylar growth and mandibular form, therefore, became some of the chief factors in the prognosis of facial growth, as far as pattern was concerned. An attempt was made to combine the long axis of the condyle with the plane of the body of the mandible in a technique for growth estimation. It was only natural, therefore, that I received with great enthusiasm the confirmation of this concept by the implant work o’f Bjiirk.s Bjiirk’s findings went even further in degree tha.n had been originally hypothesized. This particular point should be re-emphasized again and again, since many, even after reading it and studying it, still do not understand what was found or conceive of the mechanisms involved in growth of the condyle and the direction of growth behavior of the chin. It is often referred to erroneously from the podium and in the literature. Let us state this concept, so adequately revealed by implant studies, in another way. Bjiirk placed pins in the ma.ndible and employed them for future references of superposition. From the original mandibular plane of the first recorded x-ray film, he measured t.he condyle inclination and made growth comparisons. The average change in direction of condylar growth was one of a slight upward and forward inclination of about 6 degrees. Findings in individual patients varied widely. Upward and backward directions of 16 degrees to upward and forward directions of 23 degrees were observed. This yielded a total possibility of almost 40 degrees in normal variation of condylar growth on an individual basis. Superpositioning on the implanted pins revealed no appositional growth in the area of pogonion. Furthermore, the area near the mandibular canal and the external oblique ridge was stable, while some lower borders resorbed as others showed apposition. Thus, one can probably gain a better interpretation for growth by using the ridge and canals for reference, rather than the mandibular plane which has been employed in the past. The mandibular plane still is useful for “short hauls,” and we have not dropped its usage except for periods of more than 2 years.
Bjiirk did not include the face in his publications. It. sl~~uld l)tk ~na.tlc vlca~~ that horizontal condyle growth does not. mean horizontal facial growth! l’or tht* mandible is straightening out as the genial angle incrcasrs. Ilowevcr, in som(’ patients the chin can move forward when accompa,nied by back\jrard growth 01 the condyle if depression of teeth is accomplished and bite closurt7 is effected, although this is an atypical finding. Conversely, as mentiomned previously, the typical finding of upward and forward growth of the mandibular condyle shows that the mandible grows in an arc. The angle of the mandible becomes more acute, and ramus and posterior face height increases. The muscles of mastication cause the chin to move forward. Here again the effects of bite opening can be demonstrated. Growth also may follow a long, rectangular pattern. In such cases, the face grows slightly more downward than forward, even with upward and forward growth of the mandibular condyle. Another factor which modifies the effects of condylar growth in the face is the behavior of the cranial base and movement of the housing of the glenoid fossa. However, the greatest clinical implications of the temporomandibular joint over long periods arc those of condylar growth. Direction of behavior of the chin is one characteristic which some clinicians now suspect of being modified, within certain limit,s, by orthodont.ic treatment. The problems related to vertical development. in the denture are the factors with which Schud;r-‘” is working and to which he recently has drawn attention. It seems important, therefore, for the clinician to respect the mechanics of orthodontics, because some mechanical implications are suspected. These must be added to the biologic implications of fa,cial growth for complet,e sophistica,tion in contemporary orthodontic treatment,. The amount of condylar growth is linked to sex, genet,ic factors, and constitutional or muscular type. As long as the orthodontist is dealing with a normal child, the significant fact is tha,t the child will grow. If he does not grow within the first 3 to 6 month period, he will grow in the nest. If he does not grow this year, he will grow next year. The exact nature of “growth recovery” after treatment needs more investigation. Because of uncertainties of growth, and in an effort t,o obtain maximum convenience, some clinicians have attempted to institute orthodontic therapy at the time of so-called pubertal growth spurts. In my opinion, this has been grossly overemphasized and has resulted in some nonsensical conclusions. particularly concerning girls in whom such growth is t,oo little and too late. If growth is to be used to advantage, treatment should be started when there is much growth rema,ining. It is important to obtain a good skeletal relationship in a young patient,, to creat,e a normal environment, for optimum eruption potential, and then to take advantage of growth to emwe the result. Therefore, in discu&ng normal mandibular growth or normal rondyle growtll, we should think of the condyle’s most important function as being that, of facial. growth pog,losis. It becomes a matter of the amount and direction of condylar growth. This can affect orthopedic corr&ion in a very direct manner, and it becomes an integral part of treatment planning for the orthodontist.
Volume Nwrnbsr
Temporomandibular
52 6
joint
425
BZ 12.3 12.61 )I
Fig. 4. Facial characteristics had rheumatoid arthritis, in frontal perspective.
Note
following open-bite
arrest and
of condylar growth in patient thought to have forward condyle position, as well as narrowness
426
Ricketts BIOLOGIC
INTERFEREKCE
The next cat.egory is that of biologic interference iu the growth of this condyle. Four factors of concern here arc as follows: 1. Condylar agenesis, total or partial, or condyle removal. 2. Circulatory disturbances (hemiatrophy, hppcrtrophy. or nutritional) . 3. Rheumatoid arthritis or ext.ension of bacterial infections (acute inflammations). 4. Overgrowth with condylar hyperplasia. In such interferences as those just mentioned, the first three lead to a lack of mandibular growth and t,he result is the so-called “bird face” or “Andy Gump face.” Illustrations of severe underdevelopment are not uncommon in the literature.ll Characteristic features are antegonial notching, warping of mandibular form, an extremely high mandibular plane, elongation of the symphysis, extreme divergence of the occlusal plane to the mandibular plane, and a very short posterior face accompanied by a short ramus and sometimes total absence of the condylar head (Fig. 4). Certain patients may experience a partial condyle arrest without t.otal growth incapacity. Growth is not an “all or none” proposition. In the absence of normal condylar growth, however, a lack of width in the mandible can be observed, together with a forward positioning of the condyle. The patient does not possess a normal temporomandibular joint, although the glenoid fossa might be present. Instead of a temporomandibular joint, a sphenomandibular articulation may form as the condyle articulates as far forward as the great wing of the sphenoid bone. This undoubtedly is a result of Nature’s attempt bo reach a satisfactory occlusal relationship or functional harmony in the event of condylar incapacity.12 It further accounts for the time lag in severity of obvious deformity following the first 2 or 3 years of arrested development. The severity of facial deformity follows the time when functional compensation can no longer occur in the joint. When condylar growth begins to be retarded, there seems also to be a lack of development of the eminence as a hinge-joint articulation obtains in the forward position. In this manner, the usual sliding upper compartment, of the joint is lost and rotation with limited opening by hyoid a&i&y prevails. The clinical picture is similar for agenesis and for condylar disease processes. Opposite to undergrowth is condyla,r overgrowth (Fig. 5). The clinical entity of severe unilateral hyperplasia of the mandible is not uncommon. This condition, of unknown cause, seems to be identified simply with a unilateral hyperplastic condition. One condyle outgrows the other, and severe facial asymmetry with skewing of the mandible to one side develops. Chondroma is suspected, but most biopsies fail to disclose any pathologic condition and reveal simply normal large condyle a.reas with active chondrogenic zones. This condition was reported some years ago, together with its detailed clinical, diagnostic features.13 It is usually characterized by upward and forward growth of the mandibular condyle which results in a large mandible but is atypical of Class III malocclusion. Growth of the Class III type is usually characterized by up-
Volume Number
Temporomandibular
52 6
Fig. 5. Condylar hyperplasia on left, compared to Class III large condylar head and square form of ma.ndible in ease of narrow head and high mandibular angle common in prognathism.
characteristics hyperplasia
joint
427
on right. Note compared to long,
ward and backward growth of the condyle, a long and narrow condylar head and neck, an extremely long mandibular body, and very frequently abnormal facial height anteriorly. Condylar hyperplasia, on the other hand, usually occurs with upward and forward condylar growth and lends to a massive type of mandible in which the ramus is extremely large and the posterior facial height is extremely high. In these cases, Class III malocclusions might be observed, but the most typical condition in this situation is a bilateral Class I occlusion with a preponderant tip of the occlusal plane which has been caused by a radical increase in ramus height on one side only. TRAUMATIC
INTERFERENCE
AND
GROWTH
AND
FORM
The traumatic effects of the mandibular condyle are divided into two categories: (1) macrotrauma, or extraoral trauma, and (2) microtrauma, or intraoral trauma, which can result in chronic trauma in degenerative joint disease and regression. Both are thought to affect the chondrogenic area in the mandibular condyle and directly affect growth during formation. Chronic trauma in joint disease might be discussed separately and independently from growth, but it still affects cartilage and may lead ultimately to the same clinical signs of mandibular undergrowth. By macrotrauma is meant a blow causing a condylar fracture or a joint infraction followed by healing with fibrosis and subsequent undergrowth. This clinical manifestation is almost consistent with rheumatoid arthritis, infectious
LUXATION
OF VERTEBRAE
TRAUMA
Fig. 6. Result of wearing cervical dyles and production of severe formity occurred as a result of chin was noted.
TO JOINT
collar which braced head through chin. Resorption of conClass 11 retrognathic pattern developed. This hideous demacrotrauma to t,he joint, although some resorption of the
arthritis, or condylar agenesis. This is usually the type of trauma that occurs in children’s accidents in which condyles are fractured as a result of falling, bicycle and skating mishaps, hitting dashboards, etc. Subsequent growth arrest of one or both mandibular condyles may occur, although many eases have been reported in which condyles have reunited and growth has been normal even without fracture reduction. That the joint can be inhibited or destroyed is proved by the case of a patient with a history of continued use of a neck collar for cervical vertebrae dislocation (Fig. 6). Microtrauma occurs as a long series of repeated small injurious blows or strains in the joint. These ca.n result from problems in occlusion, loss of tooth support, or functional interferences. Over a period of time, microtrauma may lead to traumatic arthrosis and arthritis with pathologic adaptations in the joint. Many scholars call these normal physiologic adaptations, but, in my opinion, the term is erroneous. This form of joint damage is similar to advanced age changes, and it is commonly seen in other joints by the orthopedic surgeon. Furstman14 showed degenerative changes in the temporomandibular joints of rats following unilateral extraction of posterior teeth.
Volume Number
52 6
Temporomandibular
joint
429
Degenerative joint disease is not well known to dental clinicians. In osteoarthritis, the cartilage disappears and the surface becomes irregular. The exposed bone becomes osteosclerotic, and lipping may occur as a result of proliferation of the perichondrium. Continued trauma continues the process. For this discussion of clinical implications in orthodontics, traumatic arthritis is particularly significant, especially in the young. Older patients may voice no clinical complaints, but they may have episodes of pain with clicking or be in chronic discomfort with many bizarre symptoms of the referred type. CASE
REPORTS
1. Patient A. P., a 34-year-old man, was treated orthodontically at the age of 15 for severe overjet and overbite. Posttreatment models show a good occlusal relation, and photographs suggest that normal facial and dental relationships were attained by the age of 17. The patient began to develop an open-bite when he was about 22 years of age, or 5 years after orthodontic treatment (Fig. 7). By the time he was 34 years old, clicking in both temporomandibular joints was severe. Function was impaired to the extent that the patient was constantly uncomfortable and had become conscious of his facial appearance. After piecing together the history from the photographs and models and studying the CASE
Fig. 7. Condition 20 years after orthodontic clusion. Note severe open-bite and Class II
treatment. relation.
This
was
previously
an
excellent
oc-
430
lZichx?tts
AI= 34
3-65
Fig. 8. Frontal and lateral tracings. Note wide mandible, which is typical Tracings show open-bite and suggestion of tongue problem, but condyle tened with short posterior facial height.
of well-formed face. is forward and flat-
Volume Number
Fig, ward
Temporomandibular
5.2 6
9. Left and right shift of condyle
laminagraph also, which
tracings characterizes
showing apparent chronic advanced
43 1
joint
condyle breakdown. traumatic arthritis.
Note
for-
Fig. 10. A, Reconstructed joint from super-positioning on normal joint of similar mandibular pattern except for condylar head. Darkened area depicts possible area of degeneration or shortening of condylar head and neck. B, If normal reconstructed mandible is positioned, bite will be closed and chin will move forward. Thus, dotted area shows shift of mandible with degenerative changes. These are hypothetical, since no longitudinal roentgenograms were available.
postretentiou head films and laminagraphs 01: tllc, ,joints, it is auggt:yt
DB
DB
8.3
12.8
IO-53
il
DB
II-7
I.57
3.58
n
C
Fig. 11. Series of head plates. A, At age 8 in 1953. B, First molars were removed 1957, when patient was 11 years 7 months of age. C, Changes 14 months later treatment, which was completed in 2 years. D, Three years after treatment, notice of occlusal plane and form of mandible in Iateral tracings.
in January, at start of asymmetry
Volume Number
52 6
Temporomandibular
joint
43 3
CASE 2. Patient D. B. (Fig. 11)) a girl, had a Class I occlusion when first observed. There was an early, severely crowded mixed dentition, and progressive extraction was decided upon. The patient was a chronic mouth breather, so the adenoids were removed in December, 1954. The molars were badly broken down and, after consultation with the patient’s dentist, all four first molars were extracted in March, 1957, to facilitate development of the arch (Fig. 11, 23). Orthodontic therapy was initiated in March, 1958. Because bhe patient had a Class I occlusion originally, only minor Class II intraoral traction appeared to be needed. Bands were removed in June, 1960. From the standpoint of occlusion and esthetics, treatment left little to be desired. All spaces were closed, and all appeared to be well (Fig. 11, C). Retention was uneventful at first, but about 2 years after treatment the patient returned with a complaint of clicking in the left joint. Examination disclosed that a mesial slide of 3 to 4 mm. had developed in the occlusion, and new records were obtained. What appeared to be degenerative joint disease was present in the right temporomandibular articulation (Fig. 11, D). A consultation was held, and the condition was explained.
Fig. 12. Serial comparison shows normal Right side is atypical, with preponderant condyle.
growth on left side between posterior growth and lack
of
ages of height
17-S
8 and 17 years. development in
12-8 R
V-9
A
Fig. 13. A, Comparison of right and left sides showing difference in condyle age of 17 years 9 months. B, Comparison of right side shows shortened condyle This suggests growth arrest and involution of condyle in addition.
B
and ramus after age
at 12.
434
Ricketts
GS 6-10
!5+j3 I
GS 8-D
4-65
I\
Fig. 14. Series of head plate tracings. Darkened area shows condyle fossa relationship. that Class II malocclusion developed in addition to mesial thrust that developed years 5 months to 6 years 10 months of age. Class I relation was obtained followi= cervical strap and Kloehn face-bow, and condyle was back almost to original position.
Note from 4 use of
Volzcme
52
Number
6
Temporomandibuhr
joint
4 35
4-570 6-10 4-5 TO 6-10
Fig. 15. Serial comparisons for Patient G. S. from 4 years 5 months to 6 years 10 months of age showing opening of Y axis and vertical dropping of chin as Class II malocclusion developed. There was no change in SNA, but forward movement of molar was consistent with normal growth. Note backward growth of condyle and eruption of lower molar.
It was decided that some cervical traction therapy should be undertaken in an effort to retract the upper denture and get the condyle back to a normal fossa relationship. The patient was not cooperative, and a dual bite continued. She experienced intermittent episodes of pain and discomfort, but for weeks at a time she was free of any symptoms other than a shift in the occlusion and what appeared to be a forward position of the mandible in occlusion. No pain was involved and the teeth were sound, but the asymmetry in the face continued to worsen. A careful tracing of the x-rays suggested that the condylar form and the condyle fossa relationship were positively normal in the early mixed dentition (Fig. 12). The condyles appeared to be smooth in contour; facial development appeared to be symmetrical and consistent with this patient’s type. A re-examination of the records suggested that the problem could have started at about the time of removal of the first molars and a loss of posterior support (Fig. 13). The postretention records indicated that forward maxillary migration occurred to explain a part of this relapse, but orthodontic treatment to a correct condyle location was doubted. Did this little girl thrust the mandible forward to occlude? CASE 3. Patient G. S., a girl seen at the age of 4 years 5 months, presented a Class I occlusion and wss placed under observation (Fig. 14, A). When the patient was seen at the age of 6 years 10 months, a Class II, Division 2 malocclusion was noted (Fig. 14, B). However, this patient now appeared to function in a pattern of dual bite. It also was suggested that what some call L’functional adaptation” was beginning to occur in the condyle or that a problem of some atypical nature was developing. The condyle fossa relationship was characterized by condylar flattening and a forward mandibular posture. Facial growth had been more vertical (Fig. 15), in spite of the fact that the patient originally appeared brachyfacial
6-10 TO 8-10
Fig. 16. Patient G. S. from 6 years 10 months to 8 years 10 months of age. Y axis closed as chin moved forward. Note distal location of condyle in spit,e of forward position of chin. Note also, in upper right, SNL4 reduction of 4 degrees and vertical growth of condyle, dupression of lower second deciduous molar, and forward migration of lower incisor.
and would be expected to grow in facial depth. With the possibility of traumatic damage, the future seemed uncertain unless the malocclusion was treated early. Treatment of the Class II relation with cervical traction of the maxillary deciduous teeth reduced the need for mandibular protraction for function, and careful comparison of the tracings revealed a change in form (Fig. 14, C). It is not known whether the maIo-cclusion and function affected growth, but it is certainly conceivable that they did in this particular instance. Perhaps, however, the restricting process was of a pathologic nature. DISCUSSION
It is well established that some kind of arthritic process is affecting the temporomandibular joint to a greater degree than most people realize, but the exact nature of this disturbance is still subject to conjecture. When the condition is unilateral, the opposite side serves as a control. In the case of bilateral involvement, the effects are more extreme and controls are lacking. The observations presented here suggest that conditions of this joint can be etiologic factors, problems in treatment, and strong regressive agents in relapses of
orthodontic
cases.
The warping
of the condylar
head and neck, the shortening
of posterior
Temporomandibular
joint
43 7
facial height, the forward migration of the condylar head, the breakdown of the eminence, open-bite production with retraction of the chin, and high mandibular plane angles constitute a syndrome. We think that the condition is of traumatic origin in patients with a propensity toward weak joints or articular weakness, but we need more proof. Systemic problems must be suspected. More women than men demonstrate problems of degenerative joints, but in cases of continued trauma sex seems to be no factor. A second question regarding the syndrome is: When does it occur? Because of the differences in condylar size in unilateral cases, one would suspect that this is entirely a growth phenomenon. Trauma could possibly limit proliferative activity of the chondrogenic zone in the condyle to produce growth deformity. However, it appears that, in addition to growth arrest, the process is involutionary in character. Actual condyle resorption appears to be occurring, and mandibular regression is demonstrated. One may ask: “Has orthodontic treatment anything to do with temporomandibular pathology?” The answer apparently may be: “Yes and no.” Apparently it can, but usually it does not. Joint changes of exactly this degenerative nature have been observed literally hundreds of times in patients who may never have received orthodontic treatment. However, some patients have been seen to experience joint problems before, during, or following orthodontic treatment. Clinical symptoms of joint derangement have been noted as occlusions were changed. Some mesial positions occur inadvertently. Therefore, why should the orthodontist invite undesirable protrusive function15 with inclined planes and removable appliances that force the condyle against the eminence ? In a healthy child growth, if normal, usually will make up for forward discrepancies; wit.hout growth, however, trauma can produce damaging results in some patients. When problems do occur during treatment, it is not known whether the original malocclusion induces functional trauma or whether trauma develops during the changes in occlusion with treatment. At any rate, the orthodontist should be mindful of the possibility of traumatic complications with orthodontic adjustments in a patient of any age. The objective of treatment is to prevent joint dysfunction and to promote normal relationships for ideal growth and development. How does this information affect orthodontics clinically? The implications are that children should be treated early-even in the deciduous dentition. Also, almost without exception, the attempt should be made clinically to overtreat the Class II malocclusion to ensure a condyle seated in the fossa but not in distal displacement. In isolated cases in which patients possess large fossae and very small condylar heads, we try not to move the condyle posterior to a juxtaposition with the eminence. We try to stress the extreme importance of reduction of open-bite or cross-bite, for many patients with open-bite eventually experience joint damage. In the orthodontist’s haste with prefabrication, lighter forces, better efficiency, and greater sophistication in mechanics, he should be reminded that
438
lTZicketts
he is not working on robots but on biologic organisms. He should he thankful that he has been relieved of some of the mechanical drudgery of years past, but he should be more concerned with diagnosis, refinements in trcatmcnt, growth and biology, and the ultimate welfare of the patient. If this presenta,tion does nothing more, it should at least prove to the clinician the importance of careful and comp1et.e diagnosis and of careful treatment carried all the way to a proper conclusion. SUMMARY
Scientific investigation and the temporomandibular joint have been discussed, together with the need for trustworthy methods for viewing the joint. Cephalometric laminagraphy with lateral and oblique views has fulfilled the requirements of a superior technique. Clinica. implications have been enumerated in light of the normal purpose and function of this joint as related to mouth-opening, the role of disarticulation of the teeth in occlusal function, and, most of all, growth or morphologic determinants of the face and jaws. Normal variation in growth of the mandibular condyle has been shown, and its implications with respect to facial form have been emphasized. Aberrations in facial growth have been shown to be due, first, to biologic involvements of the joint and, second, t,o traumatic complications. It is concluded that growth of the condyle is not affected by function in the normal sense. It is hypothesized that when excessive forces of trauma beyond normal individual tolerance are experienced, growth may be affected by pathologic phenomena. In addition, it is conjectured that, even after growth has already occurred, trauma could produce regressive or involutionasy changes that are degenerative in nature. It is suggested that in some patients traumatic arthritis with condylar degeneration may be a strong factor in orthodontic relapse. REFERENCES 1. Ricketts, R. M.: Roentgenography of the Temporomandibular Joint. In Sarnat, Bernard G. (editor) : The Temporomandibular Joint, ed. 2, Springfield, Ill., 1964, Charles C Thomas Publishers, chap. ‘7. 2. Ricketts, R. M.: Variation of Temporomandibular Joint as Revealed by Cephalometric Laminagraphy, AM. J. ORTHOD~WTICS 86: 877898, 1950. 3. Ricketts, R. M.: The Role of Cephalometrics in Prosthetic Diagnosis, J. South. California D. A. 24: 19-30, 1956. 4. Ricketts, R. M.: Abnormal Function of the Temporomandibular Joint, AM. J. OI~THODONTICS 41: 435-441, 19%. 5. Lindblom, G&&a: On the Anatomy and Function of the Temporomandibular Joint, Acta odont. scanclinav. 17: 7-287, Supp. 28, 1966. 6. Ricketts, R. M.: Laminagraphy in the Diagnosis of Temporomandibular Joint Disorders, J. Am. Dent. A. 46: 620-648, 1953. 7. Ricketts, R. M.: Facial and Denture Changes During Orthodontic Treatment as Analyzed From the Temporomandibular Joint, Axr. J. ORTHODONTICS 41: 163-179, 1955. 8. Ricketts, R. M.: A Study of Changes in the Temporomandibular Joint Associated With Treatment of Claw II Malocclusion, Am J. ORTHODONTICS 36: 918-933, 1952.
Volume
52
Number
6
Temporomandibular
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9. BjGrk, Arne: Variations in the Growth Pattern of the Human Mandible: Longitudinal Radiographic Study by the Implant Method, J. D. Res. 42: 400-411, Supp., 1963. 10. Schudy, F. F.: The Rotation of the Mandible Resulting From Growth: Its Implications in Orthodontic Treatment, Angle Orthodontist 35: 36-50, 1965. 11. Engel, M. B., and Brodie, A. G.: Condylar Growth and Mandibular Deformities, Surgery 22: 976, 1947. 12. Sarnat, Bernard G.: F&al and Neurocranial Growth After Removal of the Mandibular Condyle in the Macaca Rhesus Monkey, Am. J. Surg. 94: 19-30, 1957. 13. Ricketts, R. M.: Cephalometric Synthesis, AM. J. ORTHODONTICS 46: 647-673, 1960. 14. Furstman, Lawrence: The Effect of Loss of Occlusion Upon the Mandibular Joint, AM. J. ORTHODONTICS 51: 245-261, 1965. 15. Ricketts, R. M.: The Functional Diagnosis of Malocclusion, Tr. European Orthodont. Sot., pp. l-21, 1958. 984
Monzlment
St.
M.
Palisades,
Pacific
RICKETTR,
D.D.S.,
M.H.”
Calif.
THE orthodontist is expected to possess consummate knowledge of temporomandibular growth, morphology, function, and characteristics. He should be the master of occlusion and functional articulation. The temporomandibular joint, however, continues to cause more controversy and present more inconsistencies than any other structure with which the orthodontist is concerned. Because it is mechanical and connected with the teeth, this joint can be a@ected by traumatic phenomena. As a biologic entity, it serves unique purposes and must be approached scientifically and logically. SCIENTIFIC
INVESTIGATION
AND
THE
TEMPOROMANDIBULAR
JOINT
Any acquired knowledge obtained in a systematic manner might be classified as scientific. One of the most fundamental and primary levels of scientific investigation is that of obtaining descriptive knowledge. An investigator in a,natomy tries to explain the structural nature of his subject. In order to accomplish this technically, it is necessary to measure, and trustworthy methods must be devised by which dimensional deswiptions can be attained. The establishment of ranges of variation in structural anatomy and function is basic and is considered a scientific study. The second task of any investigator is one of logic-of organization, classification, and formulation of hypotheses. It involves the handling or control of protocol facts derived from basic technical procedure. Therefore, verification becomes a di&icult task of the clinician in a clinical science. When I was assigned the subject of “Clinical Implications of the TemporoPresented 12, 1965, *On
416
the
before as part staff
the American Association of of a panel discussion on “The
of the
University
of California
Orthodontists in Temporomandibular
at Los
Angeles.
Dallas, Texas, Joint.”
May
Volume Number
Temporomandibular
52 6
joint
4 17
mandibular Joint” as my part of this panel discussion, I decided to attempt to describe a method, to enumerate pertinent protocol facts, to formulate certain hypotheses, and to present evidence to justify certain conclusions. METHODOLOGY
In 1964, in writing about roentgenographic procedures in the temporomandibular joint,l I concluded that, essentially, two major techniques out of the dozen or so listed had come to use standardized head-holding equipment with controlled x-ray exposures. The two most usable were (1) the transcranial oblique view and (2) the body-section x-ray or laminagraphy, which has been used in the research that I started in 1947. (This technique, also called planigraphy or tomography, should not be confused with pantomyography, which is employed for dental purposes.) Laminagraphy combines cephalometrics with undistorted body sections made at standard enlargements. Duplicated views are obtained with the same accuracy as routine cephalometric roentgenograms. The DOME Xectograph, which I designed, is illustrated in Fig. 1. This technique permits the patient to be seated upright so that standard frontal and lateral or oblique cephalometric roentgenograms can be obtained at a standardized 60 inch patient-target distance. In addition, the tube is set in motion and, at prescribed depths, cuts, layers, or x-ray body sections are obtained as required and at the same size as the cephalograms. In addition to straight lateral joint “cuts,” the head can be turned to a view that is perpendicular to the transverse axis of the condyle. A 20 degree oblique standard view of the temporomandibular joint has come to be employed. One side of the mandible is aligned parallel to the film. The complete buccal occlusion, together with the ramus and joint, is oriented in one plane (Fig. 2). This oblique-view body section yields an excellent portrayal of the upper and lower third molars in addition to the tuberosity, the pterygoid plates, and exceptional deta.il of the joint itself. Laminagraphy of the joint is used in conjunction with frontal and lateral standard cephalometrics. In clinical practice it has come into routine use for all orthodontic cases. Laminagraphy is essential to the diagnosis of pathologic conditions of the joint. Cuts in other planes are pa,rticularly useful in cleft palate dia,gnosis. ROLE
OF THE
TEMPOROMANDIBULAR
JOINT
IN
RELATION
TO
PhTHOLOGIC
CONDITIONS
On numerous occasions I have published findings on normal form and function,2-4 and I find no reason to alter those values. Lindblom,5 using controlled transcranial views and stereoptics, essentially corroborated my findings. However, it may be fruitful to discuss clinical implications in view of this joint’s functions or the total role that it plays. Therefore, three main functions of this joint may be listed: 1. Its role in the act of mouth opening. 2. Its role in dental articulation or functional occlusion.
418
Rick&s
@v,
Fig. 1. I )OME Sectograph for c~ephalometric rocntgenograplly aud i:c,1)II:Llomt,t~il. lamir lagra consi stin g of oriented at p shot, head-holding apparatus, moving caesettc racok, depth indicator overk lead driving rod (above), track for moving x-ray hbc, and rotating anode I ube, centered in illustration at 5 foot distance for routine head films (helow\
Volume Number
Fig.
Temporomanndibular
52 6
2. Lateral
20 degree
oblique
laminagraph.
Note
structures
in focus
in this
joint
4 19
plane.
3. Its growth function and the effects of subsequent degeneration or breakdown that might occur under pathologic conditions. This joint usually can be made to hinge for, roughly, the first half of the normal extent of opening, although the typical patient translates the condyle forward quite early in the act. As a provision for wide mouth-opening without obstruction of the airway by retraction of the chin, the condyle is brought far forward or the head is tilted backward. Limited opening is typical in patients with condyle fractures. Size and shape of the mandible have been shown to be related to the opening and closing movements. By anatomic arrangement, it is the role of the external pterygoid muscle to stabilize, protect, or modify the respiratory airway and provide the mechanism for protruding the mandible during speech. This muscle further helps to control the delicate movements of incision a.nd lateral excursion. The external pterygoid lies almost parallel to the functioning surface of the joint which it must cause to slide. During a slide, a resistance can introduce friction, and pathologic situations appa.rently can be established rather easily. Thus, one of the primary functions of this joint is to provide a mechanism for opening and protrusion of the mandible, and for this a slide is necessary. When this translatory movement cannot be obtained, functional impairment results. The second consideration, in terms of purpose and function of this joint, is its role in relation to articulation of the teeth. I have stated on numerous occaof the teeth. Portions of the dentition sions that this joint is a disarticulator are separated and sections of the arches are brought into functional relationship
420
IZicketts
for a particular activity, instead of all the teeth WCiLYillg against all tllck othc’l teeth all of the t.ime. Under this scheme, thcrc is a conser\ra tzion ot’ II~IIW~I~Y energy, a conservation of tooth tissue, and a beautiful and harmonious pattern in normal occlusion and normal functional art,itulation. During incision the condylo is brought forwa.rd and, with normal joint form and normal overbite, t.he posterior teeth are not, in contact. The condyle, b! moving forward on the eminence, must also move downward. By virtue of this relationship, the posterior teeth are disarticulated. Stresses and wear on the posterior teeth are prevented as fun&ion is directed to the anterior portion of the denture. In lateral excursions, the condyle is brought downward a.nd forward on the eminence on one side only. The ipsilateral condyle rotates. Contact. in t,he cuspid or corner of the elliptical arch form is obtained unila.t.erally. Disarticulation is obtained on a unilateral basis, a.nd forces are still directed at one particular area in the denture, at the curve of the a,rc of the dental arch. This function has been referred to as “cuspid protect.ion” (Fig. 3). The normal pattern of function is cxcrcised in complete muscular harmony. The teeth act as receptors and are closely linked by neurologic reflexes to the muscles and joint. Functional patterns with smoot,h, integrated patterns of muscle coordination are obtained and controlled by the neuromuscular circuit.
Fig. teeth
3. During lateral of that side while
excursion, downward and cuspid contact disarticulates
forward posterior
condyle teeth
movements of Tvorking”
disarticulate side.
Volume Number
52 6
Temporomandibular
joint
42 1
In 1953 I published an analysis of 180 pathologic cases.O A premise was made that temporomandibular joint disease stemmed from problems in functional occlusion. Four distinct types of traumatic joint disturbance seemed to accrue from four different types of clinical malocclusion. The first of these conditions (Type I) was abnormal overjet, characterized by the typical Class II, Division 1 relationship. The patient would move the mandible forward in compensation for the protruding teeth during incision and speech, but the condyle usually was drawn backward to a normal position in the fossa in forced occlusion (although some patients sustain a mesial displacement). An abnormal range of function stresses the joint and thus results in condyle trauma. Type II was identified as true distal thrust or posterior displacement. When the condyle was dislocated backward, it apparently lodged behind the bulbous portion of the articular disc, and clicking or snapping became audible. The inclines of the teeth could cause this type of displa,cement by influencing muscular and ligamentous structures. Another type of problem (Type III) was one of interference phenomenon. Contralateral tooth contact (opposite to the working side) upsets the normal integrated pattern of movement, and traumatic conditions in one or both joints subsequently occur. If the posterior teeth on the left side contact during the mandible’s lateral excursion to the right, trauma is experienced. Normally, the overbite of the cuspids and premolars helps separate the teeth of the opposite side. I concluded that there is no such thing as a so-called balancing side in normal occlusions. On the contrary, when balancing cusps were found, joint pathosis often was present. Type IV was one of loss of posterior support. Although all joints sustain contact, this joint is not designed for heavy weight-bearing and, with the loss of posterior teeth, it may become overstressed. If force becomes continuous, the joint breaks down as a result of excessive pressures of long duration. Degenerative joint disease is progressive and has been shown to result from a single traumatic episode. Continued trauma produces continuous re-injury. When interferences develop in occlusion, the muscle patterns become distorted and function becomes confused. Actual mechanical trauma set up by occlusal interferences will either wear the teeth, loosen the teeth, or jar the joint. Thus, tooth attrition, periodontal breakdown, or traumatic arthritis can develop. Indeed, all three of these conditions can prevail in the same person, although it is possible that only one of them may occur. If the condyle is already forward, or if the eminence is flat, there can be no separation or disarticulation of the posterior teeth. In that case, a situation of wear or trauma on the teeth is set up and severe attrition results. If a small condyle is placed posteriorly in a large fossa, no functional eminence results during the early phase of excursion, although an eminence may actually be present. Because of the la.ck of condyle juxtaposition with the eminence, there is no separation of the posterior teeth. This can be demonstrated by pushing the mandible directly from side to side. In either of these situations, the teeth wear excessively. This is exactly what
Lack of eminence height or absence of a functioning joint also is a factor in clinical diagnosis, for traumatic joint conditions ostensibly can occur even in children. For instance, a patient wit.h a slight Class II malocclusion who also has slight ailway limitat.ions in the pharynx might adapt, to a forward mandibular position. No functional eminence results, particularly in the young, a.nd the condyle may begin to be pathologically t,raumatized. CONDYLE
GROWTH
The overwhelming clinical significance of the temposromandibular joint is related to growth of the mandible. On the basis of my observations, I took the stand that function did not influence mandibular growth.7 This related to the concept of release of pressure by a pulling forward of the condyle out of the confines of a fossa, which did not cause the mandible to grow. Patients in whom this phenomenon was observed did not experience a,n increased amount of growth in the mandible. Distal displacement did not appear to be a growthlimiting factor because of overwhelming growth turgor in the normal healthy child. On the basis of recent evidence, however, it is conceivable (but sheer speculation at this point) that growth can be affected, but because of excessive traumatic function with pathologic regression. Could forward positions of the mandible damage the condyle, influence cartilage growth, and alter mandibular growth and form? Growth should be discussed from the standpoint of (1) normal growth significance of the condyle, (2) results of a biologic interference, and (3) relationships following traumatic interference. For more than a decade, I have described growth of the condyle as it influences the development of the mandible, first, as an explanation of changes during treatment and, second, as a biologic background for prognosis of growth during orthodontic treatment. Variation in growth was described from studies with laminagraph sections through the condyle, ramus, and part of the mandible. It was observed, after superimposing on the lower border of the mandible, that average growth tended to proceed almost directly up the long axis of the condylar head.* The chin allegedly would be directed downward and forward by upward and backward growth of the mandibular condyle. This seemed to be an acceptable description of normal behavior and served at least as a working hypothesis or an explanation of chin behavior. It also wa,s observed however, that not all faces developed in a constantly parallel fashion. Development might follow a generally constant pattern of consistent change toward a longer face (vertical increases). At the opposite extreme, deeper faces or horizontal increases were observed. Thus, dolichofacial (long) patterns or brachyfacial (short, square) characteristics tended to develop in consistent directions, although gradients in growth were not necessarily
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even. Slight variations were observed, but one distinguished type did not tend to reverse or transpose to another distinguished type. In the distinction of these types, I showed in 1952, that in patients who developed greater facial length mandibles tended to become more obtuse.8 These patients developed higher mandibular plane angles with growth and their condyles grew more posteriorly than straight up the condyle axis. This finding came as a shock; it had always been assumed that a more backward direction of condylar growth would lead to a forward position of the chin, but such was not the case. Backward condylar growth, with obtusely developing mandibles, was observed in patients whose chins were moving downward or downward and backwa,rd, just opposite to the formerly conceived pattern. At the other extreme, those patients dereloping facial squareness (brachyfacial characteristics), with chins that were observed to move straight forward from a cephalometric standpoint, were identified as having preponderantly upward and forward condylar growth. The mandible was growing more in an arc and contributing to a forward swing of the chin. Facial height in this type was not increasing at the sa.me rate as facial depth. Condylar growth and mandibular form, therefore, became some of the chief factors in the prognosis of facial growth, as far as pattern was concerned. An attempt was made to combine the long axis of the condyle with the plane of the body of the mandible in a technique for growth estimation. It was only natural, therefore, that I received with great enthusiasm the confirmation of this concept by the implant work o’f Bjiirk.s Bjiirk’s findings went even further in degree tha.n had been originally hypothesized. This particular point should be re-emphasized again and again, since many, even after reading it and studying it, still do not understand what was found or conceive of the mechanisms involved in growth of the condyle and the direction of growth behavior of the chin. It is often referred to erroneously from the podium and in the literature. Let us state this concept, so adequately revealed by implant studies, in another way. Bjiirk placed pins in the ma.ndible and employed them for future references of superposition. From the original mandibular plane of the first recorded x-ray film, he measured t.he condyle inclination and made growth comparisons. The average change in direction of condylar growth was one of a slight upward and forward inclination of about 6 degrees. Findings in individual patients varied widely. Upward and backward directions of 16 degrees to upward and forward directions of 23 degrees were observed. This yielded a total possibility of almost 40 degrees in normal variation of condylar growth on an individual basis. Superpositioning on the implanted pins revealed no appositional growth in the area of pogonion. Furthermore, the area near the mandibular canal and the external oblique ridge was stable, while some lower borders resorbed as others showed apposition. Thus, one can probably gain a better interpretation for growth by using the ridge and canals for reference, rather than the mandibular plane which has been employed in the past. The mandibular plane still is useful for “short hauls,” and we have not dropped its usage except for periods of more than 2 years.
Bjiirk did not include the face in his publications. It. sl~~uld l)tk ~na.tlc vlca~~ that horizontal condyle growth does not. mean horizontal facial growth! l’or tht* mandible is straightening out as the genial angle incrcasrs. Ilowevcr, in som(’ patients the chin can move forward when accompa,nied by back\jrard growth 01 the condyle if depression of teeth is accomplished and bite closurt7 is effected, although this is an atypical finding. Conversely, as mentiomned previously, the typical finding of upward and forward growth of the mandibular condyle shows that the mandible grows in an arc. The angle of the mandible becomes more acute, and ramus and posterior face height increases. The muscles of mastication cause the chin to move forward. Here again the effects of bite opening can be demonstrated. Growth also may follow a long, rectangular pattern. In such cases, the face grows slightly more downward than forward, even with upward and forward growth of the mandibular condyle. Another factor which modifies the effects of condylar growth in the face is the behavior of the cranial base and movement of the housing of the glenoid fossa. However, the greatest clinical implications of the temporomandibular joint over long periods arc those of condylar growth. Direction of behavior of the chin is one characteristic which some clinicians now suspect of being modified, within certain limit,s, by orthodont.ic treatment. The problems related to vertical development. in the denture are the factors with which Schud;r-‘” is working and to which he recently has drawn attention. It seems important, therefore, for the clinician to respect the mechanics of orthodontics, because some mechanical implications are suspected. These must be added to the biologic implications of fa,cial growth for complet,e sophistica,tion in contemporary orthodontic treatment,. The amount of condylar growth is linked to sex, genet,ic factors, and constitutional or muscular type. As long as the orthodontist is dealing with a normal child, the significant fact is tha,t the child will grow. If he does not grow within the first 3 to 6 month period, he will grow in the nest. If he does not grow this year, he will grow next year. The exact nature of “growth recovery” after treatment needs more investigation. Because of uncertainties of growth, and in an effort t,o obtain maximum convenience, some clinicians have attempted to institute orthodontic therapy at the time of so-called pubertal growth spurts. In my opinion, this has been grossly overemphasized and has resulted in some nonsensical conclusions. particularly concerning girls in whom such growth is t,oo little and too late. If growth is to be used to advantage, treatment should be started when there is much growth rema,ining. It is important to obtain a good skeletal relationship in a young patient,, to creat,e a normal environment, for optimum eruption potential, and then to take advantage of growth to emwe the result. Therefore, in discu&ng normal mandibular growth or normal rondyle growtll, we should think of the condyle’s most important function as being that, of facial. growth pog,losis. It becomes a matter of the amount and direction of condylar growth. This can affect orthopedic corr&ion in a very direct manner, and it becomes an integral part of treatment planning for the orthodontist.
Volume Nwrnbsr
Temporomandibular
52 6
joint
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BZ 12.3 12.61 )I
Fig. 4. Facial characteristics had rheumatoid arthritis, in frontal perspective.
Note
following open-bite
arrest and
of condylar growth in patient thought to have forward condyle position, as well as narrowness
426
Ricketts BIOLOGIC
INTERFEREKCE
The next cat.egory is that of biologic interference iu the growth of this condyle. Four factors of concern here arc as follows: 1. Condylar agenesis, total or partial, or condyle removal. 2. Circulatory disturbances (hemiatrophy, hppcrtrophy. or nutritional) . 3. Rheumatoid arthritis or ext.ension of bacterial infections (acute inflammations). 4. Overgrowth with condylar hyperplasia. In such interferences as those just mentioned, the first three lead to a lack of mandibular growth and t,he result is the so-called “bird face” or “Andy Gump face.” Illustrations of severe underdevelopment are not uncommon in the literature.ll Characteristic features are antegonial notching, warping of mandibular form, an extremely high mandibular plane, elongation of the symphysis, extreme divergence of the occlusal plane to the mandibular plane, and a very short posterior face accompanied by a short ramus and sometimes total absence of the condylar head (Fig. 4). Certain patients may experience a partial condyle arrest without t.otal growth incapacity. Growth is not an “all or none” proposition. In the absence of normal condylar growth, however, a lack of width in the mandible can be observed, together with a forward positioning of the condyle. The patient does not possess a normal temporomandibular joint, although the glenoid fossa might be present. Instead of a temporomandibular joint, a sphenomandibular articulation may form as the condyle articulates as far forward as the great wing of the sphenoid bone. This undoubtedly is a result of Nature’s attempt bo reach a satisfactory occlusal relationship or functional harmony in the event of condylar incapacity.12 It further accounts for the time lag in severity of obvious deformity following the first 2 or 3 years of arrested development. The severity of facial deformity follows the time when functional compensation can no longer occur in the joint. When condylar growth begins to be retarded, there seems also to be a lack of development of the eminence as a hinge-joint articulation obtains in the forward position. In this manner, the usual sliding upper compartment, of the joint is lost and rotation with limited opening by hyoid a&i&y prevails. The clinical picture is similar for agenesis and for condylar disease processes. Opposite to undergrowth is condyla,r overgrowth (Fig. 5). The clinical entity of severe unilateral hyperplasia of the mandible is not uncommon. This condition, of unknown cause, seems to be identified simply with a unilateral hyperplastic condition. One condyle outgrows the other, and severe facial asymmetry with skewing of the mandible to one side develops. Chondroma is suspected, but most biopsies fail to disclose any pathologic condition and reveal simply normal large condyle a.reas with active chondrogenic zones. This condition was reported some years ago, together with its detailed clinical, diagnostic features.13 It is usually characterized by upward and forward growth of the mandibular condyle which results in a large mandible but is atypical of Class III malocclusion. Growth of the Class III type is usually characterized by up-
Volume Number
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52 6
Fig. 5. Condylar hyperplasia on left, compared to Class III large condylar head and square form of ma.ndible in ease of narrow head and high mandibular angle common in prognathism.
characteristics hyperplasia
joint
427
on right. Note compared to long,
ward and backward growth of the condyle, a long and narrow condylar head and neck, an extremely long mandibular body, and very frequently abnormal facial height anteriorly. Condylar hyperplasia, on the other hand, usually occurs with upward and forward condylar growth and lends to a massive type of mandible in which the ramus is extremely large and the posterior facial height is extremely high. In these cases, Class III malocclusions might be observed, but the most typical condition in this situation is a bilateral Class I occlusion with a preponderant tip of the occlusal plane which has been caused by a radical increase in ramus height on one side only. TRAUMATIC
INTERFERENCE
AND
GROWTH
AND
FORM
The traumatic effects of the mandibular condyle are divided into two categories: (1) macrotrauma, or extraoral trauma, and (2) microtrauma, or intraoral trauma, which can result in chronic trauma in degenerative joint disease and regression. Both are thought to affect the chondrogenic area in the mandibular condyle and directly affect growth during formation. Chronic trauma in joint disease might be discussed separately and independently from growth, but it still affects cartilage and may lead ultimately to the same clinical signs of mandibular undergrowth. By macrotrauma is meant a blow causing a condylar fracture or a joint infraction followed by healing with fibrosis and subsequent undergrowth. This clinical manifestation is almost consistent with rheumatoid arthritis, infectious
LUXATION
OF VERTEBRAE
TRAUMA
Fig. 6. Result of wearing cervical dyles and production of severe formity occurred as a result of chin was noted.
TO JOINT
collar which braced head through chin. Resorption of conClass 11 retrognathic pattern developed. This hideous demacrotrauma to t,he joint, although some resorption of the
arthritis, or condylar agenesis. This is usually the type of trauma that occurs in children’s accidents in which condyles are fractured as a result of falling, bicycle and skating mishaps, hitting dashboards, etc. Subsequent growth arrest of one or both mandibular condyles may occur, although many eases have been reported in which condyles have reunited and growth has been normal even without fracture reduction. That the joint can be inhibited or destroyed is proved by the case of a patient with a history of continued use of a neck collar for cervical vertebrae dislocation (Fig. 6). Microtrauma occurs as a long series of repeated small injurious blows or strains in the joint. These ca.n result from problems in occlusion, loss of tooth support, or functional interferences. Over a period of time, microtrauma may lead to traumatic arthrosis and arthritis with pathologic adaptations in the joint. Many scholars call these normal physiologic adaptations, but, in my opinion, the term is erroneous. This form of joint damage is similar to advanced age changes, and it is commonly seen in other joints by the orthopedic surgeon. Furstman14 showed degenerative changes in the temporomandibular joints of rats following unilateral extraction of posterior teeth.
Volume Number
52 6
Temporomandibular
joint
429
Degenerative joint disease is not well known to dental clinicians. In osteoarthritis, the cartilage disappears and the surface becomes irregular. The exposed bone becomes osteosclerotic, and lipping may occur as a result of proliferation of the perichondrium. Continued trauma continues the process. For this discussion of clinical implications in orthodontics, traumatic arthritis is particularly significant, especially in the young. Older patients may voice no clinical complaints, but they may have episodes of pain with clicking or be in chronic discomfort with many bizarre symptoms of the referred type. CASE
REPORTS
1. Patient A. P., a 34-year-old man, was treated orthodontically at the age of 15 for severe overjet and overbite. Posttreatment models show a good occlusal relation, and photographs suggest that normal facial and dental relationships were attained by the age of 17. The patient began to develop an open-bite when he was about 22 years of age, or 5 years after orthodontic treatment (Fig. 7). By the time he was 34 years old, clicking in both temporomandibular joints was severe. Function was impaired to the extent that the patient was constantly uncomfortable and had become conscious of his facial appearance. After piecing together the history from the photographs and models and studying the CASE
Fig. 7. Condition 20 years after orthodontic clusion. Note severe open-bite and Class II
treatment. relation.
This
was
previously
an
excellent
oc-
430
lZichx?tts
AI= 34
3-65
Fig. 8. Frontal and lateral tracings. Note wide mandible, which is typical Tracings show open-bite and suggestion of tongue problem, but condyle tened with short posterior facial height.
of well-formed face. is forward and flat-
Volume Number
Fig, ward
Temporomandibular
5.2 6
9. Left and right shift of condyle
laminagraph also, which
tracings characterizes
showing apparent chronic advanced
43 1
joint
condyle breakdown. traumatic arthritis.
Note
for-
Fig. 10. A, Reconstructed joint from super-positioning on normal joint of similar mandibular pattern except for condylar head. Darkened area depicts possible area of degeneration or shortening of condylar head and neck. B, If normal reconstructed mandible is positioned, bite will be closed and chin will move forward. Thus, dotted area shows shift of mandible with degenerative changes. These are hypothetical, since no longitudinal roentgenograms were available.
postretentiou head films and laminagraphs 01: tllc, ,joints, it is auggt:yt
DB
DB
8.3
12.8
IO-53
il
DB
II-7
I.57
3.58
n
C
Fig. 11. Series of head plates. A, At age 8 in 1953. B, First molars were removed 1957, when patient was 11 years 7 months of age. C, Changes 14 months later treatment, which was completed in 2 years. D, Three years after treatment, notice of occlusal plane and form of mandible in Iateral tracings.
in January, at start of asymmetry
Volume Number
52 6
Temporomandibular
joint
43 3
CASE 2. Patient D. B. (Fig. 11)) a girl, had a Class I occlusion when first observed. There was an early, severely crowded mixed dentition, and progressive extraction was decided upon. The patient was a chronic mouth breather, so the adenoids were removed in December, 1954. The molars were badly broken down and, after consultation with the patient’s dentist, all four first molars were extracted in March, 1957, to facilitate development of the arch (Fig. 11, 23). Orthodontic therapy was initiated in March, 1958. Because bhe patient had a Class I occlusion originally, only minor Class II intraoral traction appeared to be needed. Bands were removed in June, 1960. From the standpoint of occlusion and esthetics, treatment left little to be desired. All spaces were closed, and all appeared to be well (Fig. 11, C). Retention was uneventful at first, but about 2 years after treatment the patient returned with a complaint of clicking in the left joint. Examination disclosed that a mesial slide of 3 to 4 mm. had developed in the occlusion, and new records were obtained. What appeared to be degenerative joint disease was present in the right temporomandibular articulation (Fig. 11, D). A consultation was held, and the condition was explained.
Fig. 12. Serial comparison shows normal Right side is atypical, with preponderant condyle.
growth on left side between posterior growth and lack
of
ages of height
17-S
8 and 17 years. development in
12-8 R
V-9
A
Fig. 13. A, Comparison of right and left sides showing difference in condyle age of 17 years 9 months. B, Comparison of right side shows shortened condyle This suggests growth arrest and involution of condyle in addition.
B
and ramus after age
at 12.
434
Ricketts
GS 6-10
!5+j3 I
GS 8-D
4-65
I\
Fig. 14. Series of head plate tracings. Darkened area shows condyle fossa relationship. that Class II malocclusion developed in addition to mesial thrust that developed years 5 months to 6 years 10 months of age. Class I relation was obtained followi= cervical strap and Kloehn face-bow, and condyle was back almost to original position.
Note from 4 use of
Volzcme
52
Number
6
Temporomandibuhr
joint
4 35
4-570 6-10 4-5 TO 6-10
Fig. 15. Serial comparisons for Patient G. S. from 4 years 5 months to 6 years 10 months of age showing opening of Y axis and vertical dropping of chin as Class II malocclusion developed. There was no change in SNA, but forward movement of molar was consistent with normal growth. Note backward growth of condyle and eruption of lower molar.
It was decided that some cervical traction therapy should be undertaken in an effort to retract the upper denture and get the condyle back to a normal fossa relationship. The patient was not cooperative, and a dual bite continued. She experienced intermittent episodes of pain and discomfort, but for weeks at a time she was free of any symptoms other than a shift in the occlusion and what appeared to be a forward position of the mandible in occlusion. No pain was involved and the teeth were sound, but the asymmetry in the face continued to worsen. A careful tracing of the x-rays suggested that the condylar form and the condyle fossa relationship were positively normal in the early mixed dentition (Fig. 12). The condyles appeared to be smooth in contour; facial development appeared to be symmetrical and consistent with this patient’s type. A re-examination of the records suggested that the problem could have started at about the time of removal of the first molars and a loss of posterior support (Fig. 13). The postretention records indicated that forward maxillary migration occurred to explain a part of this relapse, but orthodontic treatment to a correct condyle location was doubted. Did this little girl thrust the mandible forward to occlude? CASE 3. Patient G. S., a girl seen at the age of 4 years 5 months, presented a Class I occlusion and wss placed under observation (Fig. 14, A). When the patient was seen at the age of 6 years 10 months, a Class II, Division 2 malocclusion was noted (Fig. 14, B). However, this patient now appeared to function in a pattern of dual bite. It also was suggested that what some call L’functional adaptation” was beginning to occur in the condyle or that a problem of some atypical nature was developing. The condyle fossa relationship was characterized by condylar flattening and a forward mandibular posture. Facial growth had been more vertical (Fig. 15), in spite of the fact that the patient originally appeared brachyfacial
6-10 TO 8-10
Fig. 16. Patient G. S. from 6 years 10 months to 8 years 10 months of age. Y axis closed as chin moved forward. Note distal location of condyle in spit,e of forward position of chin. Note also, in upper right, SNL4 reduction of 4 degrees and vertical growth of condyle, dupression of lower second deciduous molar, and forward migration of lower incisor.
and would be expected to grow in facial depth. With the possibility of traumatic damage, the future seemed uncertain unless the malocclusion was treated early. Treatment of the Class II relation with cervical traction of the maxillary deciduous teeth reduced the need for mandibular protraction for function, and careful comparison of the tracings revealed a change in form (Fig. 14, C). It is not known whether the maIo-cclusion and function affected growth, but it is certainly conceivable that they did in this particular instance. Perhaps, however, the restricting process was of a pathologic nature. DISCUSSION
It is well established that some kind of arthritic process is affecting the temporomandibular joint to a greater degree than most people realize, but the exact nature of this disturbance is still subject to conjecture. When the condition is unilateral, the opposite side serves as a control. In the case of bilateral involvement, the effects are more extreme and controls are lacking. The observations presented here suggest that conditions of this joint can be etiologic factors, problems in treatment, and strong regressive agents in relapses of
orthodontic
cases.
The warping
of the condylar
head and neck, the shortening
of posterior
Temporomandibular
joint
43 7
facial height, the forward migration of the condylar head, the breakdown of the eminence, open-bite production with retraction of the chin, and high mandibular plane angles constitute a syndrome. We think that the condition is of traumatic origin in patients with a propensity toward weak joints or articular weakness, but we need more proof. Systemic problems must be suspected. More women than men demonstrate problems of degenerative joints, but in cases of continued trauma sex seems to be no factor. A second question regarding the syndrome is: When does it occur? Because of the differences in condylar size in unilateral cases, one would suspect that this is entirely a growth phenomenon. Trauma could possibly limit proliferative activity of the chondrogenic zone in the condyle to produce growth deformity. However, it appears that, in addition to growth arrest, the process is involutionary in character. Actual condyle resorption appears to be occurring, and mandibular regression is demonstrated. One may ask: “Has orthodontic treatment anything to do with temporomandibular pathology?” The answer apparently may be: “Yes and no.” Apparently it can, but usually it does not. Joint changes of exactly this degenerative nature have been observed literally hundreds of times in patients who may never have received orthodontic treatment. However, some patients have been seen to experience joint problems before, during, or following orthodontic treatment. Clinical symptoms of joint derangement have been noted as occlusions were changed. Some mesial positions occur inadvertently. Therefore, why should the orthodontist invite undesirable protrusive function15 with inclined planes and removable appliances that force the condyle against the eminence ? In a healthy child growth, if normal, usually will make up for forward discrepancies; wit.hout growth, however, trauma can produce damaging results in some patients. When problems do occur during treatment, it is not known whether the original malocclusion induces functional trauma or whether trauma develops during the changes in occlusion with treatment. At any rate, the orthodontist should be mindful of the possibility of traumatic complications with orthodontic adjustments in a patient of any age. The objective of treatment is to prevent joint dysfunction and to promote normal relationships for ideal growth and development. How does this information affect orthodontics clinically? The implications are that children should be treated early-even in the deciduous dentition. Also, almost without exception, the attempt should be made clinically to overtreat the Class II malocclusion to ensure a condyle seated in the fossa but not in distal displacement. In isolated cases in which patients possess large fossae and very small condylar heads, we try not to move the condyle posterior to a juxtaposition with the eminence. We try to stress the extreme importance of reduction of open-bite or cross-bite, for many patients with open-bite eventually experience joint damage. In the orthodontist’s haste with prefabrication, lighter forces, better efficiency, and greater sophistication in mechanics, he should be reminded that
438
lTZicketts
he is not working on robots but on biologic organisms. He should he thankful that he has been relieved of some of the mechanical drudgery of years past, but he should be more concerned with diagnosis, refinements in trcatmcnt, growth and biology, and the ultimate welfare of the patient. If this presenta,tion does nothing more, it should at least prove to the clinician the importance of careful and comp1et.e diagnosis and of careful treatment carried all the way to a proper conclusion. SUMMARY
Scientific investigation and the temporomandibular joint have been discussed, together with the need for trustworthy methods for viewing the joint. Cephalometric laminagraphy with lateral and oblique views has fulfilled the requirements of a superior technique. Clinica. implications have been enumerated in light of the normal purpose and function of this joint as related to mouth-opening, the role of disarticulation of the teeth in occlusal function, and, most of all, growth or morphologic determinants of the face and jaws. Normal variation in growth of the mandibular condyle has been shown, and its implications with respect to facial form have been emphasized. Aberrations in facial growth have been shown to be due, first, to biologic involvements of the joint and, second, t,o traumatic complications. It is concluded that growth of the condyle is not affected by function in the normal sense. It is hypothesized that when excessive forces of trauma beyond normal individual tolerance are experienced, growth may be affected by pathologic phenomena. In addition, it is conjectured that, even after growth has already occurred, trauma could produce regressive or involutionasy changes that are degenerative in nature. It is suggested that in some patients traumatic arthritis with condylar degeneration may be a strong factor in orthodontic relapse. REFERENCES 1. Ricketts, R. M.: Roentgenography of the Temporomandibular Joint. In Sarnat, Bernard G. (editor) : The Temporomandibular Joint, ed. 2, Springfield, Ill., 1964, Charles C Thomas Publishers, chap. ‘7. 2. Ricketts, R. M.: Variation of Temporomandibular Joint as Revealed by Cephalometric Laminagraphy, AM. J. ORTHOD~WTICS 86: 877898, 1950. 3. Ricketts, R. M.: The Role of Cephalometrics in Prosthetic Diagnosis, J. South. California D. A. 24: 19-30, 1956. 4. Ricketts, R. M.: Abnormal Function of the Temporomandibular Joint, AM. J. OI~THODONTICS 41: 435-441, 19%. 5. Lindblom, G&&a: On the Anatomy and Function of the Temporomandibular Joint, Acta odont. scanclinav. 17: 7-287, Supp. 28, 1966. 6. Ricketts, R. M.: Laminagraphy in the Diagnosis of Temporomandibular Joint Disorders, J. Am. Dent. A. 46: 620-648, 1953. 7. Ricketts, R. M.: Facial and Denture Changes During Orthodontic Treatment as Analyzed From the Temporomandibular Joint, Axr. J. ORTHODONTICS 41: 163-179, 1955. 8. Ricketts, R. M.: A Study of Changes in the Temporomandibular Joint Associated With Treatment of Claw II Malocclusion, Am J. ORTHODONTICS 36: 918-933, 1952.
Volume
52
Number
6
Temporomandibular
joint
43 9
9. BjGrk, Arne: Variations in the Growth Pattern of the Human Mandible: Longitudinal Radiographic Study by the Implant Method, J. D. Res. 42: 400-411, Supp., 1963. 10. Schudy, F. F.: The Rotation of the Mandible Resulting From Growth: Its Implications in Orthodontic Treatment, Angle Orthodontist 35: 36-50, 1965. 11. Engel, M. B., and Brodie, A. G.: Condylar Growth and Mandibular Deformities, Surgery 22: 976, 1947. 12. Sarnat, Bernard G.: F&al and Neurocranial Growth After Removal of the Mandibular Condyle in the Macaca Rhesus Monkey, Am. J. Surg. 94: 19-30, 1957. 13. Ricketts, R. M.: Cephalometric Synthesis, AM. J. ORTHODONTICS 46: 647-673, 1960. 14. Furstman, Lawrence: The Effect of Loss of Occlusion Upon the Mandibular Joint, AM. J. ORTHODONTICS 51: 245-261, 1965. 15. Ricketts, R. M.: The Functional Diagnosis of Malocclusion, Tr. European Orthodont. Sot., pp. l-21, 1958. 984
Monzlment
St.