Extraction, orthodontic treatment, and craniomandibular dysfunction J. M. H. Dibbets and L. Th. van der Weele Groningen, The Netherlands

Signs and symptoms attributed to craniomandibular dysfunction (CMD) were registered in the Groningen longitudinal prospective study over a 15-year period. It is concluded that none of the three treatment types--removable appliances, Begg mechanics, and chin cups--should be considered causal factors for the signs and symptoms registered many years later. Furthermore, a comparison was made among nonextraction, extraction of all first premolars, and extraction of other teeth with regard to CMD and it was concluded that the original growth pattern that caused the teeth to be selected for extraction-rather than the extraction itself-is the most likely factor responsible for the frequency of CMD reported years later. This conclusion agrees with one based on a previously postulated idea about the relationship between dysfunction symptoms and growth patterns. (AMJ ORTHOD DENTOFACORTHOP1991 ;99:210-9.)

M u c h confusion exists over the precise relationship between orthodontic factors on the one hand and signs and symptoms of craniomandibular disorders or dysfunction on the other. Alternately, occlusion, orthodontic anomalies, and treatment procedures are considered responsible for the reported symptoms. Although the relationship between occlusion and dysfunction has been studied for several decades, it appears that occlusal interferences are still regarded as causal factors by some authors, 18 while they are considered of minor importance by others. 9"~4 To quote Zarb: "Compelling evidence correlating tooth position irrefutably with increased risk of TMJ dysfunction is not available. ''x5 On the relationship between dysfunction and orthodontic anomalies there is ample literature. 6.t°.tr-3° Motsch 3~ presented a literature review containing 109 references , and he concluded that the frequency of dysfunction problems in patients with dysgnathic jaws differed only slightly from that in patients with eugnathic jaws. It appears that a consistent relationship between orthodontic malocclusion and CMD has not been established. The relationship between orthodontic treatment and dysfunction has been documented in several recent studies. a25° Despite suggestive case reports, studies have failed to find a causal relationship between the types of treatment and posttreatment dysfunction. 32,34.36,4~-51 From the Departmentof Orthodontics,Schoolof Dentistry, Universityof Gronhagen. 8/1/18470

210

Long-term studies, especially, are unanimous on this point? 3s~ Fairly recently, the problem of extraction became linked to dysfunction when some researchers connected the reports of symptoms with records of previous extractions. 464g'52 The profession is beginning to formulate an answer. 53"54 Our study analyzes the relationship between orthodontic treatment types and extractions, on the one hand, to signs and symptoms as registered in the Groningen longitudinal CMD study, on the other. The analysis is based on comparison between subsamples of this closed study group. Only by this method can unknown effects--introduced when an untreated and thus morphologically different sample is used as a control--be excluded. Inferences and statistical conclusions have to be restricted to information drawn from an orthodontically treated population. MATERIAL AND METHOD

The study, which was prospectively designed, allows the analysis of longitudinal data on the development of CMD in an orthodontically treated sample. The patients, all referred to the Department of Orthodontics of the University of Groningen, were assigned to the study without any selection as to dysfunction criteria. From January 1970 to April 1972, information was recorded on 172 patients before the start of their respective treatments. Fifty-five percent were girls. The average age was 12.5 years; 88% were between 8 and 15 years of age. The distribution of the Angle classification was 14% for Class I, 69% for Class II, and 17% for Class III.

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Extraction, orthodontic treatment, and CMD

211

sub

ob 4030-

2o:

100 0 1 2 3 a, N=173 161 158 155 109

. . . . . . . . . . . . . . . . . .

.

years

S;10 103

S~15 109

Fig. 1. CMD symptom frequencies through time. Sub, Subjectively communicated symptoms: clicking, pain, limitation of mouth opening. Ob, Objectively palpated clicking and crepitation. X, "Deformed or flattened" condylar projection on infracranial contact radiographs with the mouth opened maximally. Frequencies registered at the timepoint t = 0 before orthodontic treatment started to t = 1, 2, 3, and 4 years later. At 10 years after the start of this investigation (t = S + 10) and at 15 years (t = S + 15), follow-up examinations were given. The vertical axis denotes symptom percentages. The horizontal axis denotes time. N, Number of individuals involved. Sub continues to increase; Ob and X level off after 4 years.

The group treated with removable appliances (39%) underwent mostly some type of functional treatment. The group with fixed appliances (44%) was treated with Begg Class I and II mechanics. Seventeen percent were treated with either Begg Class III mechanics or chincup (14 hours per day minimum, 500 gm tension on each side). Thirty-four percent of the study group was treated without extractions; in 29%, all four first premolars were removed ("4 _+_ 4") and in 37% other extractions were performed. The teeth extracted included lateral incisors, two upper premolars, four second premolars, and first or second molars. The decisions to extract and what to extract were based on profile analysis and arch discrepancy considerations, but these decisions were sometimes ruled out by caries conditions. After prelim° inary statistical analysis, we decided to separate the group in whom the first premolars were extracted from the groups with other extractions. The three resulting groups contained adequate numbers for statistical testing. After 4 years, 109 patients were on recall; in 1980, there were 103; and in 1985, 111 patients volunteered for the follow-up study. Because data for some patients were not complete, these numbers may fluctuate throughout the analysis. Between 1970 and 1975, the documentation was repeated at l-year intervals. The time of documentation is indicated as t = 0 for the start of orthodontic treatment t o t = 1, t = 2, t = 3, a n d t = 4 f o r e a c h e n suing year. A protocol was used to collect prespecified items on dysfunction. For the present analysis, no sep-

aration between unilateral or double-sided symptoms

was attempted. At each documentation the protocol was completed, and among others a lateral cephalogram and infracranial open-mouth projections were made according to the method of Parma. The documentation was repeated at 10 years and 15 years after the start of this investigation, in 1980 and in 1985. These time points are indicated as t = S + I0 and t = S + 15, respectively. Craniomandibular dysfunction was registered in three categories as follows: Subjectively perceived symptoms. Symptoms reported by the subject during questioning and categorized as clicking, pain, or limited ability to open the mouth. The investigator pointed to the joint and asked: "Does it ever hurt?" "Does it ever click?" "Do you ever experience limited opening? ,,36.42 Objectively identified symptoms. Symptoms detected by the investigator after light palpation of the joints bilaterally and a request that the subject open his or her mouth as widely as possible. These symptoms are categorized as clicking and crepitation. Component X: The appearance of the condyle on the infracranial open-mouth radiograph was categorized at sight as deformed or flattened, "yes" or "no." Because this judgment depends greatly on experience, it was performed by a single researcher, who described the procedure in great detail in 1966. ~°The construction of an index was considered inappropriate. ~5 Tables and graphs were constructed from the observations registered at the specific time points and X2 tests were performed. The level of significance was

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Table I. Distribution o f subjectively perceived symptoms and objectively identified symptoms before orthodontic treatment (0) and approximately 15 years later, according to the Angle classification

Class (%)

Symptoms Subjective At 0yr At 15yr Objective At0yr At l5yr

I

I

Class 11 (%)

]

Class 111 (%)

I

30 79

23 62

0* 58

46 64

21 40

10" 26

,×5 significant:p < 0.05

Table II. Distribution of nonextraction group, group in which all four first premolars were extracted, and group with all other types of extraction, according to treatment type modes

Group Nonextractions First premolar extraction Other extractions Total Average age (yr)

Removable appliance

Begg I and H

39 (59) 3 (5)

5 (7) 41 (55)

24 (36) 66 11.4

29 (39) 75 14.4

I

Class III

I

Total

Average age O'r)

14 (47) 5 (17)

58 49

10.8 13.3

I1 (37) 30 10. l

64 171

13.4

Table III. Distribution o f group with no extractions, group in which all four first premolars were extracted, and group with all other types of extraction, according to the Angle classification

oro No extractions First premolar extraction Other types of extraction Total Average age (yr)

i

C,ass, 5 (21) 15 (62) 4(17) 24 14.2

I

C,ass,, 40 (34) 29 (25) 4__29(42) l 18 12.8

et = 0.05. Two questions were analyzed: (1) Is orthodontic treatment ultimately connected with C M D ? (2) Do extractions affect the incidence of C M D ? RESULTS

The prevalence of symptoms is depicted in Fig. 1. The prevalence of subjectively perceived symptoms (sub in the graph) increased throughout the study period from 20% to 62%. Clicking and crepitation prevalence (ob in the graph) increased from 23% before treatment to 36% after 4 years and then stabilized. The prevalence o f deformities or flattening, observed radiographically, increased only slightly from the start to 4 years later and then stabilized at around 25%.

I

I 13 (45) 5 (17) 11 (38) 29 I0.0

o,o, 58 49 64 171

I

Avero eo e , 10.8 13.3 13.4

The distribution of CMD over the Angle classification is depicted in Table I. Before orthodontic treatment had even started, the frequency of subjectively perceived symptoms and objectively identified symptoms was significantly different statistically in the three Angle classes. Table II shows the relationship between the decision to extract and the types of treatment. There were differing preferences for each of the treatment regimens, as could be expected. Nonextraction was preferred with removable appliances, first premolars were the teeth most often extracted, with Begg mechanics. The other extractions were distributed uniformly over the types of treatment.

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Extraction, orthodontic treatment, and CMD

% 80 70 60 50 4030-

213

Sub B I,II

~

REM CI [11

20-

10 0

t

= 0

1

2

3

4

S +10

S

+15

Fig. 2. Subjectively communicated symptoms: clicking, pain, limitation of mouth opening and tre~itment modalities. (For legends, see Fig. 1.) B I II, Begg mechanics, Class I and II cases. REM, Removable appliances, mainly functional. CI III, Begg Class Ill mechanics or chin cup. No significantly different symptom frequencies for the three types of treatment after 10 and 15 years. */9 < 0.05. % 60"

Ob

50.

B I,II REM

40, 30. ---e

20" 10. 0

CI Ill

r .-e" =0

1

2

3

4

S +10

S +15

Fig. 3. Objectively palpated clicking or crepitation and treatment modalities. (For Legends, see Fig. 1.) B I II, Begg mechanics, Class I and II cases. REM, Removable appliances, mainly functional. Cl III, Begg Class I11mechanics or chin cup. No significantly different symptom frequencies for the three types of treatment after 10 and 15 years. *p < 0.05.

Table IlI displays the relationship between the decision to extract and the Angle classification. The decision to extract first premolars obviously is distributed differently over the classes, compared with both of the other categories. The prevalence of CMD in the three types of treatment and the results of statistical testing are depicted in Figs. 2 through 4. It may be observed that before any orthodontic treatment had started, the initial assignment of patients to one of the three treatment regimens had produced three groups with significantly differing symptom frequencies. Four years later, after treatment and retention, these differences appeared to be significant only for palpated clicks and crepitation and not for subjective clicks, pain, or limitation of mouth opening or for radiographic deformities or fiat-

tening. After 10 years, and again after 15 years, all three types of treatment had equal symptom frequencies, although Class III treatment had a notably lower frequency of objectively determined symptoms. The prevalence of CMD in the three extraction groups and the results of statistical testing are depicted in Figs. 5 through 10. The frequency of subjectively identified clickhzg (Fig. 5) was not registered as significantly different between the nonextraction group and the other two groups during orthodontic treatment and retention (t = 0, I, 2, 3, and 4). After 10 and 15 years, the frequencies in the nonextraction group and other extractions group became equal. However, the frequencies for the first-premolar extraction group always exceeded both of the others, although not to a significant degree until after 15 years. Reports of pain and Ihni-

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Dibbets and van der Weele

% 60 50

302010O"

X

~

40

= 0

1

........

B I,II • CI III

e- . . . . . . . . . . .

REM

2

3

4

S +10

S

+15

Fig. 4. =Deformed or f[attened~ condylar projection on infracranial contact radiographs (with the mouth opened maximally) and treatment types. (For legends, see Fig. 1.) B I I/, Begg mechanics, Class I and II cases. REM, Removable appliances, mainly functional. CI ill, Begg Class III mechanics or chin cup. No significantly different symptom frequencies for the three types of treatment after 10 and 15 years. *p < 0.05.

% 90

Sub c 4±4

.e

80. 70 60" .--'"

50

other non

40 30 20 10" O" = 0

1

2

3

4

S +10

S

+15

Fig. 5. Subjectively communicated clicking frequencies in three groups: nonextraction, four firstpremolar extraction (4 +- 4), and any other type of extraction. (For legends, see Fig. 1.) Subjectively perceived clicking was reported at significantly higher frequencies after 15 years for the group in which all four first premolars had been extracted. See discussion for comments. *p < 0.05.

% 60 50

Sub p

40 .e

30 20

4+4 NON

other

10' 0 = 0

1

2

3

4

S +10

S

+15

Fig. 6. Pain reported in three groups: no extractions, extraction of all four first premolars (4 - 4), and all other types of extraction. (For legends, see Fig. 1.) Pain is distributed similarly at all time points.

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Extraction, orthodontic treatment, and CMD

215

% 60" 50 40" 30"

Sub I

20. 10. O.

-e

_- ~~ =0

........ 1

2

3

~

4

S +i0

~

4+-4

non • other S +15

Fig. 7. Subjectively perceived limitation of mouth opening in three groups: no extractions, extraction

of all four first premolars (4 -- 4), and all other types of extraction. (For legends, see Fig. 1.) Reports of limited mouth opening are distributed similarly at all time points.

% 60 50

Ob c

40

r°-O--

4+4 . . . . . . . . . . . . .

-0

. . . . . . . . .

30 20

non

10 0

=0

i

2

3

4

S+10

S+15

Fig. 8. Objectively identified clicking frequencies in three groups: no extractions, extraction of all four first premolars, (4 _ 4), and all other types of extraction. (For legends, see Fig. 1.) Objectively determined clicking is recorded at constantly higher frequencies at all time points for the group in which all four first premolars were extracted. Therefore, the selection for extraction, rather than the extraction itself, appears to be the criterion related to the incidence of posttreatment clicking.

tation of mouth openhzg were distributed similarly over the three groups at all time points during the 15 years of this study, as may be seen in Figs. 6 and 7. Palpated clickhlg frequencies are depicted in Fig. 8. At no time point was there a significant difference among the three groups, but it is obvious that frequency for the first-premolar extraction group parallels that of both other groups at the higher levels. Crepitation was reported at all time points in equally low percentages in the three groups, as may be seen in Fig. 9. The frequencies of diagnosed deformed or flattened condyles were significantly different during the first 3 years, with the first premolar extraction group scoring highest. After 10 and 15 years, there was no longer any difference, as can be seen in Fig. 10. DISCUSSION Prevalence

Fig. 1 shows the prevalence of subjectively identified clicking, pain, or limitation of mouth opening, increasing from before the onset of orthodontic treatment to 15 years later. Objectively identified frequen-

cies of clicking or crepitation, as well as diagnoses of condylar deformities orflattenhzg from infracranial radiographs, in contrast, level off after 4 years. However, in individual patients, symptoms may come and go; they are by no means stable characteristics. 56 Control group

At this point, a most important question arises: Are differences of CMD symptom registrations in different subsamples caused by the sampling factor, or are they contaminated by hidden correlations with other variables? It is important to note that the decision to use a sample of untreated controls as a reference is considered methodologically incorrect. This procedure would introduce a sample group of subjects who had never needed orthodontic treatment and, consequently, would have different characteristics with regard to CMD. Our study concerns effects of orthodontic procedures on CMD development, and lhtts both the study groups and the reference group must contain comparable samples of subjects in need of orthodontic treatment. Unfortunately, even this restriction does not prevent adverse

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Am. J. Orthod. Dentofac. Orthop. March 1991

Dibbets and van der Weele

% 60 50 40 30

O b cr other

20 .B ..............

10

- - - ~ = . .~. . . . . . .

~



4±4

0 =0

1

2

3

4

S +10

S +15

Fig. 9. Objectively identified crepitation frequencies in three groups: no extractions, extraction of all four first premolars (4 -- 4), and all other types of extraction. (For legends, see Fig. 1.) Objectively identified crepitation is distributed similarly at all time points.

% 6050

X

40•

30-"

20-



~

4+4

= other

100 = 0

1

2

3

4

S +10

S

+15

Fig. 10. Diagnosed =deformed or flattened" condylar projection ("X") in three groups: no extractions, extraction of all four first premolars (4 ___4), and all other types of extraction. (For legends, see Fig. 1.) "Deformed or flattened" condylar projections are distributed similarly after 10 and 15 years. *p < 0.05.

sampling effects. In Table I it may be seen that Class I always showed the highest CMD frequencies, before ireatment as well as 15 years later. Crass III, on the other hand, always showed much lower percentages, while Class II occupied an intermediate position. Since the literature reports only minor differences in percentages of symptoms between the Angle classes, 3' one might wonder whether the subjects with truly severe anomalies who were referred to the clinic in the 1970s represented a n o r m a l orthodontic population. Treatment modalities

Age most probably accounts for the statistically different percentages during the first years of the study for the three types of treatment, as seen in Figs. 2 through 5. At the start of this study, the patients in the group with Class I and Class II occlusion who were being treated with the Begg fixed appliance were 3 to 4 years older than patients in both other treatment groups (see Table II). The misleading effect of age on CMD was studied previously by a comparison between children just out of retention and children of the same age who

were yet untreated because they had been referred at an older age. 45 The overriding influence of age disappears after 10 years. Apparently, an age difference in the early teens has a more dramatic influence on CMD symptom frequencies than it has in the 20s. The three treatment groups had similar CMD frequencies after 10 or more years, and thus the idea that one of these types of treatment is specifically harmful to the temporomandibular joint must be rejected. Since the biomechanical principles of all three treatment types are comp!etely different and even evoke opposite reactions in the TMJ region, any relationship between orthodontic treatment and CMD has to be rejected. None of the three treatment types--removable appliances, Begg mechanics, and chincups--relate to the symptoms registered. Extractions

From Table III it follows that the decision for nonextraction and the decisions for any other types of extraction, except that of first premolars, were distributed similarly over the three Angle classes, while the

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Extraction, orthodontic treatment, and CMD 2| 7

decision to extract first premolars shows a deviant distribution. This choice was made in 63% of the Class I group and in only 17% of the Class III group. As a consequence, higher Class I CMD percentages will contaminate the first-premolar extraction group most strongly, while they then are not counterbalanced by the low percentages of Class III CMD. Therefore the precise relationship between CMD and extraction will remain unknown. For subjectively identified clicking, Fig. 5 shows no statistically significant differences in frequency among the three groups during the first 10 years of the study. However, after 15 years, the frequency of clicking in the first-premolar extraction group significantly exceeds that for both of the others. It also appears that the objectively identified click was registered at all timepoints more frequently in the first-premolar extraction group than in both other groups. This difference is evidenced by the upper curve in Fig. 8, which parallels both others, beginning before the extractions were even performed. Since any relationship between CMD and treatment biomechanics is rejected, Begg treatment, with its emphasis on first premolars, cannot be considered as a causal factor in CMD. Thus the suggestion that adverse sampling effects were caused by stratification with respect to extractions is strengthened. Selection for extraction appears to be the criterion responsible for higher frequencies of CMD, rather than the extraction itself. When Figs. 5 through 10 are considered in combination, it is evident that over a 15-year period there exists no relationship at all between the choice of not to extract or to extract either first premolars or any other teeth and the registration of pain, limitation of mouth opening, crepitation, and radiologic signs. The literature relates these signs and symptoms to internal derangement of the temporomandibular joint, 5759 but there exists some controversy. 6°'61Clicking frequencies, whether subjectively or objectively identified, were always higher in the first-premolar extraction g r o u p - even before the extractions were performed. The decision for or against extraction was certainly not taken at random, since it was based on profile analysis and arch discrepancies. Furthermore, our studies show a connection between CMD symptoms and facial configuration. 42"6~As a consequence, there is evidence in support of the following chain: CMD signs and toms42.62

symp-

Growth patterns ~ Decision with respect to extraction

Their common denominator, the growth pattern, suggests a spurious component in the assumed relationship between extraction and subsequent CMD. CONCLUSIONS

We reached the following conclusions as a result of our research: 1. The three types of orthodontic treatment applied in this study--removable appliances, Begg Class I and II mechanics, and Class III mechanics--appear to have no relationship to reported symptoms of CMD many years after completion of treatment. 2. Symptoms that indicate serious CMD p r o b l e m s - for example, pain, limitation of mouth opening, and crepitation or condylar deformation--do not appear to be related to nonextraction, to first-premolar extraction, or to any other type of extraction. 3. Clicking joints do not appear to be associated with nonextraction therapy or with any type of extraction therapy, except for therapy that involves extraction of first premolars. 4. Selection for extraction of the four first premolars apparently segregates a population with a higher, but not significantly higher, frequency of objectively identified clicking. 5. It appears that those criteria which, in 1970, led the practitioner to prescribe first-premolar extraction were the same criteria that gave rise, in the long run, to subjectively identified clicking. It is impossible with the material at hand to know whether to ascribe this reported clicking to the extraction or to sampling effects--especially to selection for orthodontic treatment, which, in turn, is related to growth patterns. Henk Flanderijn constructed the graphs from the computer output. Lilian Gaillard performed indispensable and accurate secretarial assistance. Dr. J. T. Wilmink assisted in the final preparation of the text. Prof. Dr. G. Boering initiated the collection of data. Dr. W. F. Suurenbroek and Dr. R. K. Kraal supervised the followups. Luida Noordhof assured reference backup. REFERENCES

1. SlavicekR. Das stomatognatheSystem. InformOrthod Kieferorthop 1981;13:281-99. 2. LindblomG. Physiologyof the temporomandibularjointand the relation between joint and teeth. Ned Tijdschr Tandheelk 1956;63:505-10. 3. PerryHT. Relationofocelusionto temporomandibularjointdysfunction. The orthodontic viewpoint. J Am Dent Assoc 1969; 79:137-41. 4. Roth RH. Temporomandibularpain-dysfunctionand occlusalrelationships. Angle Orthod 1973;43:136-54. 5. RichardsLC, BrownT. Dentalattritionand degenerativearthritis of the temporomandibularjoint. J Oral Rehabil 1981;8:293-307.

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6. Egermark-Eriksson 1, lngervall B. Anomalies of occlusion predisposing to occlusal interference in children. Angle Orthod 1982;52:293-9. 7. Weinberg LA. The role of stress occlusion, and condyle position in TMJ dysfunction pain. J Prosthet Dent 1983;49:532-45. 8. Ramfjord SP, Ash MH. Occlusion. 3rd ed. Philadelphia: Saunders, 1983. 9. Rieder CE, Martinoff JT. The prevalence of mandibular dysfunction. Part II. A multiphasie dysfunction profile. J Prosthet Dent 1983;50:237-44. 10. Boering G. Arthrosis deformans van het kaakgewricht. Leiden: Stafleu en Tholen, 1966, 94-110. 11. Budtz-J6rgensen E, Luan W, Holm-Pedersen P, Fejerskov O. Mandibular dysfunction related to dental, occlusal and prosthetic conditions in a selected elderly population. Gerodontics 1985; 1:28-33. 12. Carlson GE, Droukas BCh. Dental occlusion and the health of the masticatory system. J Craniomandib Pract 1984;2:141-7. 13. Storey AT. The neuropbysiology of temporomandibular disorders. In: Carlson DS, McNamara JA, Ribbens KA, eds. Developmental aspects of temporomandibularjoint disorders. Ann Arbor: Center for Human Growth and Development, University of Michigan, 1985:115-44. 14. Meng HP, Dibbets JMH, Weele LTh van der, Boering G. Symptoms of temporomandibular joint dysfunction and predisposing factors. J Prosthet Dent 1987;57:215-22. 15. Zarb G. Developmental aspects of temporomandibular joint disorders. In: Carlson DS, McNamara JA, Ribbens KA, eds. Developmental aspects of temporomandibular joint disorders. Ann Arbor: Center for Human Growth and Development, University of Michigan, 1985:105-13. 16. Furlong FJ. A radiographic investigation of the temporomandibular joint in Class 111 malocclusion. [Master's Thesis] Chicago: Northwestern University, 1954. 17. Williamson EH. Temporomandibular dysfunction in pretreatment adolescent patients. AM J OR'HIOD 1977;72:429-33. 18. Mohlin B. Need for orthodontic treatment with special reference to mandibular dysfunction. [Thesis]. G6teborg, Sweden: University of G6teborg, 1982. 19. Mohlin B, Thilander B. The importance of the relationship between malocclusion and mandibular dysfunction and some clinical applications in adults. Eur J Orthod 1984;6:192-204. 20. Moyers RE. The development of occlusion and temporomandibular joint disorders. In: Carlson DS, McNamara JA, Ribbens KA, eds. Developmental aspects of temporomandibular joint disorders. Ann Arbor: Center for Human Growth and Development, University of Michigan, 1985:53-70. 21. Herzog G, Boentaran D, lngervall B. Symptome der mandibuliiren Dysfunktion bet Kindern und Jugendlichen mit Malokklusion. Sehweiz Monatsschr Zahnmed 1985;95:390-400. 22. Nesbitt BA, Moyers RE, Tenttave T. Adult temporomandibular joint disorder symptomatology and its association with childhood occlusal relations. In: Carlson DS, McNamara JA, Ribbens KA, eds. Developmental aspects of temporomandibular joint disorders. Ann Arbor: Center for Human Growth and Development, University of Michigan, 1985:183-90. 23. Pullinger AG, Hollender L, Solberg WK, Petersson A. A tomographic study of mandibular condyle position in an asymptomatie population. J Prosthet Dent 1985;53:706-13. 24. Lindquist B, Olsson M. Mandibular function in children before orthodontic treatment compared with the status in children with no need for orthodontic treatment. Abstr Eur Soc Orthod 1985;25.

25. Stringert HG, Worms FW. Variations in skeletal and dental patterns with structural and functional alterations of the temporomandibular joint: a preliminary report. AM J ORTHOD 1986; 89:285-97. 26. Solberg WK, Bibb CA, Nordstr6m BB, Hansson TL. Malocclusion associated with temporomandibular joint changes in young adults at autopsy. AM J OR'I'tIOD 1986;89:326-30. 27. Riolo ML, Brandt D, TenHave TR. Associations between occlusal characteristics and signs and symptoms of TMJ dysfunction in children and young adults. AM J OR'moP DEr,rrOFAC ORTHOP 1987;92:467-77. 28. Ahlgren J. Mandibular growth and dysfunction: a cephalometric and electromyographic analysis of a cross-bite case. Br J Orthod 1975;2:195-200. 29. Brandt D. Temporomandibular disorders and their association with morphologie malocclusion in children. In: Carlson DS, McNamara JA, Ribbens KA, eds. Developmental aspects of temporomandibular joint disorders. Ann Arbor: Center for Human Growth and Development, University of Michigan, 1985: 279-98. 30. Rakosi T. Funktionelle Kiefergelenkst6mngen bet Kindem. Fortschr Kieferorthop 1971;32:37-57. 31. Motsch A. Epidemiologie funktioneller St6mngen. Dtsch Zahniirztl Z 1985;40:147-55. 32. Reichbom-Kjennemd AM. Functional adaptation of the temporomandibularjoints and bite raising by means of an AndressenHiiupl activator in a case of distocclusion. Odontol Tidskr 1964;72:305-11. 33. Mathews JR. Functional considerations of the temporomandibular articulation and orthodontic implications. Angle Orthod

1967;37:81-93. 34. Pancherz H. Long-term effects of activator (Andresen appliance) treatment. Odontol Revy (Supp 35), 1976. 35. Helkimo M. Epidemiologic surveys of dysfunction of the masticatory system. Oral Sci Rev 1976;7:54-66. 36. Dibbers JMH. Juvenile temporomandibularjoint dysfunction and eraniofacial growth: a statistical analysis. Leiden: Stafleu en Tholen, 1977. 37. Greene CS. Orthodontics and the temporomandibular joint. Angle Orthod 1982;52:166-72. 38. Solberg WK. Current concepts on the development of TMJ dysfunction. In: Carlson DS, McNamara JA, Ribbens KA, eds. Developmental aspects of temporomandibular joint disorders. Ann Arbor: Center for Human Growth and Development, University of Michigan, 1985:37-47. 39. Wyatt EW. Preventing adverse effects on the temporomandibular joint through orthodontic treatment. AM J ORTHOD DENTOFAC ORIHOP 1987;91:493-9. 40. Rinehuse DJ. Counterpoint: preventing adverse effects on the temporomandibular joint through orthodontic treatment. AM J ORTHOI) DEN'rOFACORaq-IOP1987;91:500-6. 41. Nilner M. Functional disturbances and diseases in the stomatognathie system among 7- to 18-year-olds. J Craniomandib Pract 1985;3:358-67. 42. Dibbets JMH, Weele LTh van der, Bocring G. Craniofacial morphology and temporomandibular joint dysfunction in children. In: Carlson DS, McNamara JA, Ribbens KA, eds. Developmental aspects of temporomandibularjoint disorders. Ann Arbor: Center for Human Growth and Development, University of Michigan, 1985:151-82. 43. Sadowsky C, Begole EA. Long-term status of temporomandibular joint function and functional occlusion after orthodontic treatment. AM J ORTIIOD 1980;78:201-12.

Volume 99 Number 3

Extraction, orthodontic treatment, and CMD

44. Sadowsky C, Poison AM. Temporomandibular disorders and functional occlusion after orthodontic treatment: results of two long-term studies. AM J ORTrIOD 1984;86:386-90. 45. Dibbets JMH, Weele LTh van der. Orthodontic treatment in relation to symptoms attributed to dysfunction of the temporomandibular joint. AM J OgraOD DEtCrOFACORTHOP 1987;91: 193-9. 46. Larsson E, R6nnerman A. Mandibular dysfunction symptoms in orthodontieally treated patients ten years after the completion of treatment. Eur J Orthod 1981;3:89-94. 47. Janson M, Hasund A. Functional problems in orthodontic patients out of retention. Eur J Orthod 1981;3:173-9. 48. Janson M. Die kieferorthop~dische Behandelung--ein Risikofaktor f ~ funktionelle und okklusale St6rungen? Dtsch Zahn~tztl Z 1985;40:432-40. 49. Wisth PJ. Mandibular function and dysfunction in patients with mandibular prognathism. AM J OR~OD 1984;85:193-8. 50. Madone G, Ingervall B. Stability of results and function of the masticatory system in patients treated with the Herren type of activator. Eur J Oahod 1984;6:92-106. 51. Dahl BL, Krogstad BS, Ogaard B, Eckersberg 1". Signs and symptoms of craniomandibular disorders in two groups of 19year-old individuals, one treated orthodontically and the other not. Acta Odontol Scand 1988;46:89-93. 52. Kirveskari P, Alanen P. Association between tooth lossand TMJ dysfunction. J Oral Rehabil 1985;12:!89-94. 53. Gianelly AA. Oahodontics, condylar position and TMJ status. AM J ORTHODDEN'I~FACORlqtOP 1989;95:521-3. 54. Gianelly AA. Condylar position and extraction treatment. AM J ORTHOD DENTOFACORTHOP 1988;93:201-5.

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55. Weele LTh van der, Dibbets JMH. Helkimo's index: a scale or just a set of symptoms? J Oral Rehabil 1987;14:229-37. 56. Weele LTh van der, Dibbets JMH. Conceptual models for analyzing symptoms of temporomandibular joint dysfunction. J Craniomandib Pract 1986;4:357-66. 57. Mejersj6 C, Carlsson GE. TMJ pain and dysfunction: relation between clinical and radiographic findings in the short and longterm. Scand J Dent Res 1984;92:241-8. 58. Hansson L-G, Hansson T, Petersson A. A comparison between clinical and radiologic findings in 259 temporomandibular joint patients. J Prosthet Dent 1983;50:89-94. 59. Kopp S, Rockier B. Relationship between clinical and radiographic findings in patients with mandibular pain-dysfunction. Acta Radiol (Stockholm) 1979;20:465. 60. lsberg A, Eliasso S. A cephalometrie analysis of patients with coronoid process enlargement and locking. AM J ORrHOD DENTOFACORTHOP 1990;97:35-40. 61. Nickerson JW, Moystad A. Observations on individuals with radiographic bilateral condylar remodeling. Oral Surg Oral Med Oral Pathol 1982;1:21-37. 62. Dibbets JMH, Weele LTh van der, Uildriks AKJ. Symptoms of dysfunction: indicators of growth patterns? J Pedod 1985;9:26584.

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AAO MEETING CALENDAR

1991uSeattle, Wash., May 11 to 15, Seattle Convention Center 1992uSt. Louis, Mo., May 10 to 13, St. Louis Convention Center 1993--Toronto, Canada, May 16 to 19, Metropolitan Toronto Convention Center 1994--Orlando, Fla., May 1 to 4, Orange County Convention and Civic Center 1995--San Francisco, Calif., May 7 to 10, Moscone Convention Center 1996mDenver, Colo., May 12-15, Colorado Convention Center

Extraction, orthodontic treatment, and craniomandibular dysfunction.

Signs and symptoms attributed to craniomandibular dysfunction (CMD) were registered in the Groningen longitudinal prospective study over a 15-year per...
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