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Computed tomography evaluation of temporomandibular joint alterations in patients with class II division 1 subdivision malocclusions: condyle-fossa relationship
ORIGINAL ARTICLE
Computed tomography evaluation of temporomandibular joint alterations in patients with Class II Division 1 subdivision malocclusions: Condyle-fossa relationship Robert Willer Farinazzo Vitral, DDS, MSc, PhD,a Carlos de Souza Telles, DDS, PhD,b Marcelo Reis Fraga, DDS, MSc,c Roberto Sotto Maior Fortes de Oliveira, DDS, MSC,c and Orlando Motohiro Tanaka, DDS, MSc, PhDd Juiz de Fora, Rio de Janeiro, and Curitiba, Brazil Thirty persons with Class II Division 1 subdivision malocclusions, ranging in age from 12 years 8 months to 42 years, underwent computed tomography of the temporomandibular joints. The images obtained from sagittal slices were used to assess the depth of the mandibular fossa, the angulation of the posterior wall of the articular tubercle, the condyle-fossa relationship, and the concentric position of the condyles associated with this malocclusion. Paired Student t tests were applied, and Pearson product moment correlations (r) were determined after measurements on both Class I and Class II sides were obtained. No statistically significant asymmetries were found in the depth of the mandibular fossa, the angulation of the posterior wall of the articular tubercle, or the condyle-fossa relationship. However, a statistically significant (P ⬍ .05) anterior positioning of the condyles was observed. (Am J Orthod Dentofacial Orthop 2004;126:48-52)
n a previous study,1 the dimensional and positional symmetries of the condyles were evaluated from axial computed tomography (CT) images in a sample of patients with Class II Division 1 subdivision malocclusions. Although such images provide valuable information regarding the condyles, they do not allow visualization and analysis of the condyle-fossa relationship, which would provide important complementary information. Because Class II subdivision malocclusions have a different type of occlusion on each side of the dental arch,2 visualization and analysis of the condyle-fossa relationship might be useful for evaluating whether such occlusal asymmetry can cause morphologic alterations in the joint structures and in the condyle-fossa relationship. They could also help to determine whether this type of malocclusion is due to the asymmetric position of these structures. These are controversial
I
a
Associate professor, Universidade Federal de Juiz de Fora, Brazil. Emeritus professor, Universidade Federal do Rio de Janeiro, Brazil. c Professor, Universidade Federal de Juiz de Fora, Brazil. d Associate professor, Pontifı´cia Universidade Cato´lica do Parana´, Curitiba, Brazil. Reprint requests to: Dr Robert Willer Farinazzo Vitral, Av Rio Branco 2595/1604, Juiz de Fora-MG CEP: 36010 907, Brazil; e-mail, robertvitral@ acessa.com. Submitted, April 2003; revised and accepted, June 2003. 0889-5406/$30.00 Copyright © 2004 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2003.06.012 b
48
subjects. The influence of occlusion on joint morphology is still not completely understood. Some investigators have indicated that occlusal factors are related to joint morphology,3-14 whereas others have failed to demonstrate such a correlation.15-18 Opinions also differ as to the importance of occlusion on the condylefossa relationship. Studies by Myers et al,19 Mongini,20 Mongini and Schmid,21,22 Pullinger et al,23 O’Byrn et al,24 and Schudy25 showed a significant correlation between these variables. However, Cohlmia et al26 reported no relationship between them. Burley15 evaluated the articular structures of the temporal bone in patients with different types of malocclusions (Classes I, II, and III) and showed that they do not produce functional stimuli capable of altering the contour of the anterior wall of the mandibular fossa. Ricketts27 stated that the articular components of the temporal bone and mandible are independent variables. Matsumoto and Bolognese18 found no correlation between radiographic morphologic characteristics of the temporomandibular joint (TMJ) and occlusion in a group of Class I malocclusion subjects. By evaluating human autopsy material, Solberg et al28 found a significant correlation between the shape of the condyle and the articular structures of the temporal bone. A similar finding was observed by Matsumoto and Bolognese,14 whose study on dried skulls demonstrated a significant
Vitral et al 49
American Journal of Orthodontics and Dentofacial Orthopedics Volume 126, Number 1
correlation between the shape of the condyle and the depth of the mandibular fossa. Pullinger et al23 stated that nonconcentric condylar positioning is a feature of Class II malocclusion and that the condyles are more anteriorly positioned in patients with Class II Division 1 malocclusion than in those with Class I. Cohlmia et al26 observed that subjects with malocclusions frequently show nonconcentric condylar positioning and mild condyle-fossa relationship asymmetry, in which the left condyle is placed more anteriorly than the right. Myers et al19 pointed out that, in functional posterior crossbite, the condyle is displaced superiorly on the crossbite side and inferiorly on the opposite side. Mongini,20 Mongini and Schmid,21,22 and Ben-Bassat et al29 reported that crossbites and occlusal interferences that cause condyle displacement might produce an asymmetric condylar relationship in the adult or different condylar growth rates in a growing individual, to establish a concentric relationship of the condyles with symmetric joint spaces. According to Bednar,30 visualization of the TMJ is often difficult because of its anatomy and the adjacent structures. Danforth et al31 stated that such difficulty might be eliminated by the use of CT, which allows precise visualization of anatomic details. Thus, reliable data concerning morphology, irregularities, and condyle-fossa relationship can be obtained. The purpose of this study was to investigate, with sagittal slice CT imaging, the condyle-fossa relationship and the concentric position of the condyles in a sample of subjects with Class II Division 1 subdivision malocclusion.
intervals, using the helicoidal technique. Because this procedure provides images on the axial plane, it was reformatted to produce images sagittaly. The selected imaging slices were processed in Advantage Windows I (General Electric). The measurements were determined by tracing the selected image structures. As in most CT images, the dimensions did not correspond to the real size of the structures. Therefore, a scale for measurement conversion was determined for each image. The Class I side of the dental arch was called side I, and the Class II side was called side II. The following measurements were assessed:
MATERIAL AND METHODS
Measurements of the anterior and posterior joint spaces were compared for sides I and II to evaluate the concentric position of the condyles in their respective mandibular fossae. Paired Student t tests were used for each measurement studied to evaluate the average of differences between sides I and II for each element of the sample. Pearson product moment correlation coefficients (r) were determined to quantify the degree of correlation between the values obtained on sides I and II for each measurement.
Thirty persons with Class II Division 1 subdivision malocclusions, ranging in age from 12 years 8 months to 42 years, underwent CT of the TMJs. All participants met the following requirements: all permanent teeth erupted, except third molars; no functional mandibular deviations; and no evident facial asymmetry. Symptoms of temporomandibular disorders were not considered in selecting these subjects, because most such disorders are related to disc positioning, and the purpose of this study was to evaluate the skeletal structures of the TMJ. The CT images were obtained with patients in centric occlusion (maximum dental intercuspation), and their heads were positioned so that the Frankfort and the midsagittal planes were perpendicular to the floor. The helicoidal CT was performed with a ProSpeed scanner (General Electric Medical Systems, Tokyo, Japan) with 120 kV and 160 mA. We obtained 1-mmthick tomographic imaging slices spaced at 3-mm
●
●
●
●
●
Depth of the mandibular fossa: measured from the most superior point of the fossa to the plane formed by the most inferior point of the articular tubercle to the most inferior point of the auditory meatus (Fig 1). Angulation of the posterior wall of the articular tubercle: represented by the angle between the plane of the posterior wall of the articular tubercle and the plane obtained from the most inferior point of the articular tubercle to the most inferior point of the auditory meatus (Fig 2). Anterior joint space: expressed by the shortest distance between the most anterior point of the condyle and the posterior wall of the articular tubercle (a in Fig 3). Superior joint space: measured from the shortest distance between the most superior point of the condyle and the most superior point of the mandibular fossa (s in Fig 3). Posterior joint space: represented by the shortest distance between the most posterior point of the condyle and the posterior wall of the mandibular fossa (p in Fig 3).
RESULTS
The descriptive statistics for each measurement analyzed in the comparison of structures on sides I and II are shown in Table I. The descriptive statistics for the evaluation of the concentric position of the condyles are shown in Table II. The mean depths of the mandibular fossa were 8.26
50 Vitral et al
Fig 1. Depth of mandibular fossa.
American Journal of Orthodontics and Dentofacial Orthopedics July 2004
Fig 2. Angulation of posterior wall of articular tubercle.
and 8.30 mm for sides I and II, respectively (P ⫽ .745, r ⫽ 0.822). The mean angulations of the posterior wall of the articular tubercle were 51.37° and 52.40° for sides I and II, respectively (P ⫽ .211, r ⫽ 0.867). The mean anterior joint spaces were 1.32 and 1.23 mm for sides I and II, respectively (P ⫽.350, r ⫽ 0.734). The mean superior joint spaces were 1.29 and 1.41 mm for sides I and II, respectively (P ⫽ .098, r ⫽ 0.787). The mean posterior joint spaces were 1.86 and 1.85 mm for sides I and II, respectively (P ⫽ .932, r ⫽ 0.673). In the evaluation of the concentric position of the condyles on side I, the mean values were 1.32 and 1.86 mm for the anterior and posterior joint spaces, respectively (P ⫽ .005, r ⫽ 0.079). On side II, the mean values were 1.23 and 1.85 mm for the anterior and posterior joint spaces, respectively (P ⫽ .005, r ⫽ 0.147). DISCUSSION
Fig 3. Anterior joint space (a), superior joint space (s), and posterior joint space (p).
The difficult visualization of the TMJ (due to its complex anatomy and the superimposition of adjacent structures) might be a factor responsible for the discrepancies in the results of different studies concerning this joint. Bean et al32 reported that a comparison between the images of the articular components with and without soft tissue covering often showed incompatible forms. Studies that evaluated radiographically the shapes of the temporal and mandibular structures of the TMJ found no correlation between them.18,27 On the other hand, significant correlation between these structures was found in studies on human autopsy material28 and dried skulls.14 According to Kahl et al,33 CT of the TMJ provides a detailed description of bone
structures and shows 100% agreement between the images and surgical findings. They also pointed out that the sagittal slice technique is the most appropriate to evaluate the condyle-fossa relationship, the depth of the mandibular fossa, the angulation of the articular tubercle, and the length of the condylar neck. Our results for the angulation of the posterior wall of the articular tubercle and the depth of the mandibular fossa were not statistically significant when sides I and II were compared. Moreover, high Pearson product moment correlations were found (r ⫽ 0.822 and 0.867, respectively). Nonsignificant results were also obtained when the condyle-fossa relationship was assessed through mea-
Vitral et al 51
American Journal of Orthodontics and Dentofacial Orthopedics Volume 126, Number 1
Table I.
Statistical analysis: structures on sides I and II
Depth of mandibular fossa (mm) Angulation of posterior wall of articular tubercle (°) Anterior joint space (mm) Superior joint space (mm) Posterior joint space (mm)
Side I
Side II
Side I ⫺ side II
P (paired Student t test)
8.26 (1.17) 51.37 (8.55)
8.30 (1.06) 52.40 (8.58)
⫺0.04 (0.67) ⫺1.03 (4.42)
.745 .211
0.822 0.867
1.32 (0.58) 1.29 (0.55) 1.86 (0.84)
1.23 (0.73) 1.41 (0.65) 1.85 (0.72)
0.08 (0.48) ⫺0.12 (0.39) 0.01 (0.63)
.350 .098 .932
0.734 0.787 0.673
r (Pearson product moment correlation)
Data are expressed as mean (standard deviation). Table II.
Statistical analysis: concentric position of condyles
Concentric position of condyles, side I (mm) Concentric position of condyles, side II (mm)
P (paired Student t test)
r (Pearson product moment correlation)
Anterior joint space
Posterior joint space
Anterior joint space ⫺ posterior joint space
1.32 (0.58)
1.86 (0.84)
⫺0.54 (0.98)
.005
0.079
1.23 (0.73)
1.85 (0.72)
⫺0.61 (1.10)
.005
0.147
Data are expressed as mean (standard deviation).
surements of the anterior, superior, and posterior joint spaces. A previous study,1 in which the same sample of patients was used, demonstrated that the condyles were symmetrically positioned. Associating this finding with the results in the present study, we can conclude that the mandibular fossae also show such symmetry. Christiansen et al34 evaluated 2 groups of subjects who underwent CT of the temporal bone (group I had no radiographic signs of TMJ disease, and group II had neither radiographic nor clinical signs of joint disease) and found values of 59.6° (group I) and 60.0° (group II) for the angulation of the posterior wall of the articular tubercle. However, their results cannot be compared with those of the Class II subdivision sample in our study because they did not specify the plane from which the angulation was measured. According to the literature, the most significant morphologic alterations and positioning asymmetries of the TMJ structures are related to the absence of teeth, dental abrasion, premature occlusal contact points, functional mandibular deviations, posterior crossbites, and dentoskeletal asymmetries.4-9,11,12,20,21 We assessed the concentric position of the condyles and found that the anterior joint spaces for sides I and II were significantly smaller (P ⬍ .05) than the posterior joint spaces. Therefore, we might assume that, in this sample, there was no concentric position of the condyles because they were more anteriorly positioned
in relation to their mandibular fossae. These results are in line with the views of Pullinger et al,23 who stated that it is a feature of Class II malocclusion to exhibit more anteriorly positioned condyles, compared with Class I. However, Pullinger et al23 evaluated Class II Division 1 malocclusions, which show a bilateral Class II relationship. Cohlmia et al26 evaluated the ratio of posterior to anterior joint space in Class II Division 1 patients and found values of 1.26 for the left side and 1.01 for the right. They observed that the left condyle was more anteriorly positioned than the right; that might be attributable to a unilateral pattern of mastication and cranial base asymmetries. In the Class II subdivision sample evaluated here, this ratio was 1.40 and 1.50 for sides I and II, respectively; this demonstrates less centralization on side II (although not statistically significant). Cohlmia et al26 suggested that the asymmetric position of the condyles was a characteristic of the normal population. Blaschke and Blaschke35 found considerable variation in condylar positioning in normal joints. Given the lack of a definite pattern of condylar positioning, Lam et al36 considered questionable the clinical relevance of measuring the joint spaces for diagnostic purposes. On the basis of the results from this study, it can be concluded that no centralization of the condylar process was observed, because the condyles were more anteri-
52 Vitral et al
orly positioned. We might assume that this result represents normal people and those with malocclusions. Although the Class II Division 1 subdivision sample had such characteristics, they do not seem to be unique to this type of malocclusion. CONCLUSIONS
There were no significant differences between sides I (Class I) and II (Class II) in the condyle-fossa relationship, the depth of the mandibular fossa, and the angulation of the posterior wall of the articular tubercle in the sample of Class II Division 1 subdivision patients. Evaluation of the concentric position of the condyles in their respective mandibular fossae showed a nonconcentric positioning for side I and side II; this demonstrates a statistically significant anteriorly positioned condyle. REFERENCES 1. Vitral RWF, Telles CS. Computed tomography evaluation of temporomandibular joint alterations in Class II Division 1 subdivision patients: condylar symmetry. Am J Orthod Dentofacial Orthop 2002;121:369-75. 2. Angle EH. Classification of malocclusion. Dental Cosmos 1899; 61:248-64. 3. Breitner C. Further investigations of bone changes resulting from experimental orthodontic treatment. Am J Orthod Oral Surg 1941;27:605-32. 4. Mongini F. Modificazioni dell’articolazione temporo-mandibolares nell’edentulismo parziale. Minerva Stomatol 1968;17: 850-8. 5. Mongini F. L’articolazione temporo-mandibolare nel morso profondo e nel morso incrociato. Minerva Stomatol 1968;17: 903-8. 6. Mongini F. Remodelling of the mandibular condyle in the adult and its relationship to the condition of the dental arches. Acta Anat 1972;82:437-53. 7. Mongini F. Dental abrasion as a factor in remodeling of the mandibular condyle. Acta Anat 1975;92:292-300. 8. Mongini F. Anatomic and clinical evaluation of the relationship between the temporomandibular joint and occlusion. J Prosthet Dent 1977;38:539-51. 9. Blackwood HJJ. Pathology of the temporomandibular joint. J Am Dent Assoc 1969;79:118-24. 10. Wedel A, Carlsson G, Sagne S. Temporomandibular joint morphology in a medieval skull material. Swed Dent J 1978;2:177-87. 11. Granados JI. The influence of the loss of teeth and attrition on the articular eminence. J Prosthet Dent 1979;42:78-85. 12. Richards JL, Brown T. Dental attrition and degenerative arthritis of the temporomandibular joint. J Oral Rehabil 1981;8:293-307. 13. O’Ryan F, Epker BN. Temporomandibular joint function and morphology: observations on the spectra of normalcy. Oral Surg 1984;58:272-9. 14. Matsumoto MAN, Bolognese AM. Bone morphology of the temporomandibular joint and its relation to dental occlusion. Braz Dent J 1995;6:115-22. 15. Burley MA. An examination of the relation between the radiographic appearance of the temporomandibular joint and some features of the occlusion. Br Dent J 1961;110:195-200.
American Journal of Orthodontics and Dentofacial Orthopedics July 2004
16. Dorier M, Cimasoni G. Variations de l’angle goniaque et des diedres condyliens mandibulaires en fonction de l’abrasion dentaire et de la perte des dents. Schweiz Monatsschr Zahnheil 1965;75:201-7. 17. Dorier M, Spirgi M, Nicolas GM. Variations de l’inclinasion de la paroi ante`rieure de la cavite` gle`noide de l’os temporal en fonction de l’aˆ ge, du sexe, de l’abrasion dentaires et de la perte totale des dents. Schweiz Monatsschr Zahnheil 1966;77:968-85. 18. Matsumoto MAN, Bolognese AM. Radiographic morphology of the temporomandibular joint related to occlusal characteristics. Braz Dent J 1994;5:115-20. 19. Myers DR, Barenie JT, Bell RA, Willamson EH. Condylar position in children with functional posterior crossbites: before and after crossbite correction. Pediatr Dent 1980;2:190-4. 20. Mongini F. Influence of function on temporomandibualar joint remodeling and degenerative desease. Dent Clin North Am 1983;27:479-94. 21. Mongini F, Schmid W. Treatment of mandibular asymmetries during growth. Eur J Orthod 1987;9:51-67. 22. Mongini F, Schmid W. Craniomandibular and temporomandibular joint orthopedics. Berlin: Quintessense Publishing; 1989. p. 29-46. 23. Pullinger A, Solberg W, Hollender L, Petersson A. Relationship of mandibular condylar position to dental occlusion factors in an asymptomatic population. Am J Orthod Dentofacial Orthop 1987;91:200-6. 24. O’Byrn BL, Sadowsky C, Schneider B, Begole EA. An evaluation of mandibular asymmetry in adults with unilateral posterior crossbite. Am J Orthod Dentofacial Orthop 1995;107:394-400. 25. Schudy F. Treatment of adult midline deviation by condylar repositioning. J Clin Orthod 1996;30:343-7. 26. Cohlmia JT, Ghosh J, Sinha PK, Nanda RS, Currier GF. Tomographic assessment of temporomandibular joints in patients with malocclusion. Angle Orthod 1996;66:27-36. 27. Rickets RM. Various conditions of the temporomandibular joint as revealed by cephalometric laminagraphy. Angle Orthod 1952; 22:98-105. 28. Solberg WK, Bibb CA, Nordstro¨ m BB, Hansson TL. Malocclusions associated with temporomandibular joint changes in young adults at autopsy. Am J Orthod 1986;89:326-30. 29. Ben-Bassat Y, Yaffe A, Brin I, Freeman J, Ehrlich Y. Functional and morphological-occlusal aspects in children treated for unilateral posterior cross-bite. Eur J Orthod 1993;15:57-63. 30. Bednar J. TMJ imaging. CDS Rev 1990;83:45-8. 31. Danforth RA, Otis LL, Kipnis V, Ong SH, Voss R. Corrected TMJ tomography: effectiveness of alternatives to SMV tracing. Am J Orthod Dentofacial Orthop 1991;100:547-52. ¨ berg T. Comparison between radiologic 32. Bean LR, Omneli KA, O observations and macroscopic tissue changes in temporomandibular joints. Dentomaxillofac Radiol 1997;6:90-106. 33. Kahl B, Fischbach R, Gerlach KL. Temporomandibular joint. Morphology in children after treatment of condylar fractures with functional appliance therapy: a follow-up study using spiral computed tomography. Dentomaxillofac Radiol 1995;24:37-45. 34. Christiansen EL, Chant TT, Thompson JR, Hasso JR, Hinshaw D Jr, Copp S. Computed tomography of the normal temporomandibular joint. Scand J Dent Res 1987;95:499-509. 35. Blaschke D, Blaschke T. Normal TMJ bony relationships in centric occlusion. J Dent Res 1981;60:90-104. 36. Lam PH, Sadowsky C, Omerza F. Mandibular asymmetry and condylar position in children with unilateral posterior crossbite. Am J Orthod Dentofacial Orthop 1999;115:569-75.
Computed tomography evaluation of temporomandibular joint alterations in patients with Class II Division 1 subdivision malocclusions: Condyle-fossa relationship Robert Willer Farinazzo Vitral, DDS, MSc, PhD,a Carlos de Souza Telles, DDS, PhD,b Marcelo Reis Fraga, DDS, MSc,c Roberto Sotto Maior Fortes de Oliveira, DDS, MSC,c and Orlando Motohiro Tanaka, DDS, MSc, PhDd Juiz de Fora, Rio de Janeiro, and Curitiba, Brazil Thirty persons with Class II Division 1 subdivision malocclusions, ranging in age from 12 years 8 months to 42 years, underwent computed tomography of the temporomandibular joints. The images obtained from sagittal slices were used to assess the depth of the mandibular fossa, the angulation of the posterior wall of the articular tubercle, the condyle-fossa relationship, and the concentric position of the condyles associated with this malocclusion. Paired Student t tests were applied, and Pearson product moment correlations (r) were determined after measurements on both Class I and Class II sides were obtained. No statistically significant asymmetries were found in the depth of the mandibular fossa, the angulation of the posterior wall of the articular tubercle, or the condyle-fossa relationship. However, a statistically significant (P ⬍ .05) anterior positioning of the condyles was observed. (Am J Orthod Dentofacial Orthop 2004;126:48-52)
n a previous study,1 the dimensional and positional symmetries of the condyles were evaluated from axial computed tomography (CT) images in a sample of patients with Class II Division 1 subdivision malocclusions. Although such images provide valuable information regarding the condyles, they do not allow visualization and analysis of the condyle-fossa relationship, which would provide important complementary information. Because Class II subdivision malocclusions have a different type of occlusion on each side of the dental arch,2 visualization and analysis of the condyle-fossa relationship might be useful for evaluating whether such occlusal asymmetry can cause morphologic alterations in the joint structures and in the condyle-fossa relationship. They could also help to determine whether this type of malocclusion is due to the asymmetric position of these structures. These are controversial
I
a
Associate professor, Universidade Federal de Juiz de Fora, Brazil. Emeritus professor, Universidade Federal do Rio de Janeiro, Brazil. c Professor, Universidade Federal de Juiz de Fora, Brazil. d Associate professor, Pontifı´cia Universidade Cato´lica do Parana´, Curitiba, Brazil. Reprint requests to: Dr Robert Willer Farinazzo Vitral, Av Rio Branco 2595/1604, Juiz de Fora-MG CEP: 36010 907, Brazil; e-mail, robertvitral@ acessa.com. Submitted, April 2003; revised and accepted, June 2003. 0889-5406/$30.00 Copyright © 2004 by the American Association of Orthodontists. doi:10.1016/j.ajodo.2003.06.012 b
48
subjects. The influence of occlusion on joint morphology is still not completely understood. Some investigators have indicated that occlusal factors are related to joint morphology,3-14 whereas others have failed to demonstrate such a correlation.15-18 Opinions also differ as to the importance of occlusion on the condylefossa relationship. Studies by Myers et al,19 Mongini,20 Mongini and Schmid,21,22 Pullinger et al,23 O’Byrn et al,24 and Schudy25 showed a significant correlation between these variables. However, Cohlmia et al26 reported no relationship between them. Burley15 evaluated the articular structures of the temporal bone in patients with different types of malocclusions (Classes I, II, and III) and showed that they do not produce functional stimuli capable of altering the contour of the anterior wall of the mandibular fossa. Ricketts27 stated that the articular components of the temporal bone and mandible are independent variables. Matsumoto and Bolognese18 found no correlation between radiographic morphologic characteristics of the temporomandibular joint (TMJ) and occlusion in a group of Class I malocclusion subjects. By evaluating human autopsy material, Solberg et al28 found a significant correlation between the shape of the condyle and the articular structures of the temporal bone. A similar finding was observed by Matsumoto and Bolognese,14 whose study on dried skulls demonstrated a significant
Vitral et al 49
American Journal of Orthodontics and Dentofacial Orthopedics Volume 126, Number 1
correlation between the shape of the condyle and the depth of the mandibular fossa. Pullinger et al23 stated that nonconcentric condylar positioning is a feature of Class II malocclusion and that the condyles are more anteriorly positioned in patients with Class II Division 1 malocclusion than in those with Class I. Cohlmia et al26 observed that subjects with malocclusions frequently show nonconcentric condylar positioning and mild condyle-fossa relationship asymmetry, in which the left condyle is placed more anteriorly than the right. Myers et al19 pointed out that, in functional posterior crossbite, the condyle is displaced superiorly on the crossbite side and inferiorly on the opposite side. Mongini,20 Mongini and Schmid,21,22 and Ben-Bassat et al29 reported that crossbites and occlusal interferences that cause condyle displacement might produce an asymmetric condylar relationship in the adult or different condylar growth rates in a growing individual, to establish a concentric relationship of the condyles with symmetric joint spaces. According to Bednar,30 visualization of the TMJ is often difficult because of its anatomy and the adjacent structures. Danforth et al31 stated that such difficulty might be eliminated by the use of CT, which allows precise visualization of anatomic details. Thus, reliable data concerning morphology, irregularities, and condyle-fossa relationship can be obtained. The purpose of this study was to investigate, with sagittal slice CT imaging, the condyle-fossa relationship and the concentric position of the condyles in a sample of subjects with Class II Division 1 subdivision malocclusion.
intervals, using the helicoidal technique. Because this procedure provides images on the axial plane, it was reformatted to produce images sagittaly. The selected imaging slices were processed in Advantage Windows I (General Electric). The measurements were determined by tracing the selected image structures. As in most CT images, the dimensions did not correspond to the real size of the structures. Therefore, a scale for measurement conversion was determined for each image. The Class I side of the dental arch was called side I, and the Class II side was called side II. The following measurements were assessed:
MATERIAL AND METHODS
Measurements of the anterior and posterior joint spaces were compared for sides I and II to evaluate the concentric position of the condyles in their respective mandibular fossae. Paired Student t tests were used for each measurement studied to evaluate the average of differences between sides I and II for each element of the sample. Pearson product moment correlation coefficients (r) were determined to quantify the degree of correlation between the values obtained on sides I and II for each measurement.
Thirty persons with Class II Division 1 subdivision malocclusions, ranging in age from 12 years 8 months to 42 years, underwent CT of the TMJs. All participants met the following requirements: all permanent teeth erupted, except third molars; no functional mandibular deviations; and no evident facial asymmetry. Symptoms of temporomandibular disorders were not considered in selecting these subjects, because most such disorders are related to disc positioning, and the purpose of this study was to evaluate the skeletal structures of the TMJ. The CT images were obtained with patients in centric occlusion (maximum dental intercuspation), and their heads were positioned so that the Frankfort and the midsagittal planes were perpendicular to the floor. The helicoidal CT was performed with a ProSpeed scanner (General Electric Medical Systems, Tokyo, Japan) with 120 kV and 160 mA. We obtained 1-mmthick tomographic imaging slices spaced at 3-mm
●
●
●
●
●
Depth of the mandibular fossa: measured from the most superior point of the fossa to the plane formed by the most inferior point of the articular tubercle to the most inferior point of the auditory meatus (Fig 1). Angulation of the posterior wall of the articular tubercle: represented by the angle between the plane of the posterior wall of the articular tubercle and the plane obtained from the most inferior point of the articular tubercle to the most inferior point of the auditory meatus (Fig 2). Anterior joint space: expressed by the shortest distance between the most anterior point of the condyle and the posterior wall of the articular tubercle (a in Fig 3). Superior joint space: measured from the shortest distance between the most superior point of the condyle and the most superior point of the mandibular fossa (s in Fig 3). Posterior joint space: represented by the shortest distance between the most posterior point of the condyle and the posterior wall of the mandibular fossa (p in Fig 3).
RESULTS
The descriptive statistics for each measurement analyzed in the comparison of structures on sides I and II are shown in Table I. The descriptive statistics for the evaluation of the concentric position of the condyles are shown in Table II. The mean depths of the mandibular fossa were 8.26
50 Vitral et al
Fig 1. Depth of mandibular fossa.
American Journal of Orthodontics and Dentofacial Orthopedics July 2004
Fig 2. Angulation of posterior wall of articular tubercle.
and 8.30 mm for sides I and II, respectively (P ⫽ .745, r ⫽ 0.822). The mean angulations of the posterior wall of the articular tubercle were 51.37° and 52.40° for sides I and II, respectively (P ⫽ .211, r ⫽ 0.867). The mean anterior joint spaces were 1.32 and 1.23 mm for sides I and II, respectively (P ⫽.350, r ⫽ 0.734). The mean superior joint spaces were 1.29 and 1.41 mm for sides I and II, respectively (P ⫽ .098, r ⫽ 0.787). The mean posterior joint spaces were 1.86 and 1.85 mm for sides I and II, respectively (P ⫽ .932, r ⫽ 0.673). In the evaluation of the concentric position of the condyles on side I, the mean values were 1.32 and 1.86 mm for the anterior and posterior joint spaces, respectively (P ⫽ .005, r ⫽ 0.079). On side II, the mean values were 1.23 and 1.85 mm for the anterior and posterior joint spaces, respectively (P ⫽ .005, r ⫽ 0.147). DISCUSSION
Fig 3. Anterior joint space (a), superior joint space (s), and posterior joint space (p).
The difficult visualization of the TMJ (due to its complex anatomy and the superimposition of adjacent structures) might be a factor responsible for the discrepancies in the results of different studies concerning this joint. Bean et al32 reported that a comparison between the images of the articular components with and without soft tissue covering often showed incompatible forms. Studies that evaluated radiographically the shapes of the temporal and mandibular structures of the TMJ found no correlation between them.18,27 On the other hand, significant correlation between these structures was found in studies on human autopsy material28 and dried skulls.14 According to Kahl et al,33 CT of the TMJ provides a detailed description of bone
structures and shows 100% agreement between the images and surgical findings. They also pointed out that the sagittal slice technique is the most appropriate to evaluate the condyle-fossa relationship, the depth of the mandibular fossa, the angulation of the articular tubercle, and the length of the condylar neck. Our results for the angulation of the posterior wall of the articular tubercle and the depth of the mandibular fossa were not statistically significant when sides I and II were compared. Moreover, high Pearson product moment correlations were found (r ⫽ 0.822 and 0.867, respectively). Nonsignificant results were also obtained when the condyle-fossa relationship was assessed through mea-
Vitral et al 51
American Journal of Orthodontics and Dentofacial Orthopedics Volume 126, Number 1
Table I.
Statistical analysis: structures on sides I and II
Depth of mandibular fossa (mm) Angulation of posterior wall of articular tubercle (°) Anterior joint space (mm) Superior joint space (mm) Posterior joint space (mm)
Side I
Side II
Side I ⫺ side II
P (paired Student t test)
8.26 (1.17) 51.37 (8.55)
8.30 (1.06) 52.40 (8.58)
⫺0.04 (0.67) ⫺1.03 (4.42)
.745 .211
0.822 0.867
1.32 (0.58) 1.29 (0.55) 1.86 (0.84)
1.23 (0.73) 1.41 (0.65) 1.85 (0.72)
0.08 (0.48) ⫺0.12 (0.39) 0.01 (0.63)
.350 .098 .932
0.734 0.787 0.673
r (Pearson product moment correlation)
Data are expressed as mean (standard deviation). Table II.
Statistical analysis: concentric position of condyles
Concentric position of condyles, side I (mm) Concentric position of condyles, side II (mm)
P (paired Student t test)
r (Pearson product moment correlation)
Anterior joint space
Posterior joint space
Anterior joint space ⫺ posterior joint space
1.32 (0.58)
1.86 (0.84)
⫺0.54 (0.98)
.005
0.079
1.23 (0.73)
1.85 (0.72)
⫺0.61 (1.10)
.005
0.147
Data are expressed as mean (standard deviation).
surements of the anterior, superior, and posterior joint spaces. A previous study,1 in which the same sample of patients was used, demonstrated that the condyles were symmetrically positioned. Associating this finding with the results in the present study, we can conclude that the mandibular fossae also show such symmetry. Christiansen et al34 evaluated 2 groups of subjects who underwent CT of the temporal bone (group I had no radiographic signs of TMJ disease, and group II had neither radiographic nor clinical signs of joint disease) and found values of 59.6° (group I) and 60.0° (group II) for the angulation of the posterior wall of the articular tubercle. However, their results cannot be compared with those of the Class II subdivision sample in our study because they did not specify the plane from which the angulation was measured. According to the literature, the most significant morphologic alterations and positioning asymmetries of the TMJ structures are related to the absence of teeth, dental abrasion, premature occlusal contact points, functional mandibular deviations, posterior crossbites, and dentoskeletal asymmetries.4-9,11,12,20,21 We assessed the concentric position of the condyles and found that the anterior joint spaces for sides I and II were significantly smaller (P ⬍ .05) than the posterior joint spaces. Therefore, we might assume that, in this sample, there was no concentric position of the condyles because they were more anteriorly positioned
in relation to their mandibular fossae. These results are in line with the views of Pullinger et al,23 who stated that it is a feature of Class II malocclusion to exhibit more anteriorly positioned condyles, compared with Class I. However, Pullinger et al23 evaluated Class II Division 1 malocclusions, which show a bilateral Class II relationship. Cohlmia et al26 evaluated the ratio of posterior to anterior joint space in Class II Division 1 patients and found values of 1.26 for the left side and 1.01 for the right. They observed that the left condyle was more anteriorly positioned than the right; that might be attributable to a unilateral pattern of mastication and cranial base asymmetries. In the Class II subdivision sample evaluated here, this ratio was 1.40 and 1.50 for sides I and II, respectively; this demonstrates less centralization on side II (although not statistically significant). Cohlmia et al26 suggested that the asymmetric position of the condyles was a characteristic of the normal population. Blaschke and Blaschke35 found considerable variation in condylar positioning in normal joints. Given the lack of a definite pattern of condylar positioning, Lam et al36 considered questionable the clinical relevance of measuring the joint spaces for diagnostic purposes. On the basis of the results from this study, it can be concluded that no centralization of the condylar process was observed, because the condyles were more anteri-
52 Vitral et al
orly positioned. We might assume that this result represents normal people and those with malocclusions. Although the Class II Division 1 subdivision sample had such characteristics, they do not seem to be unique to this type of malocclusion. CONCLUSIONS
There were no significant differences between sides I (Class I) and II (Class II) in the condyle-fossa relationship, the depth of the mandibular fossa, and the angulation of the posterior wall of the articular tubercle in the sample of Class II Division 1 subdivision patients. Evaluation of the concentric position of the condyles in their respective mandibular fossae showed a nonconcentric positioning for side I and side II; this demonstrates a statistically significant anteriorly positioned condyle. REFERENCES 1. Vitral RWF, Telles CS. Computed tomography evaluation of temporomandibular joint alterations in Class II Division 1 subdivision patients: condylar symmetry. Am J Orthod Dentofacial Orthop 2002;121:369-75. 2. Angle EH. Classification of malocclusion. Dental Cosmos 1899; 61:248-64. 3. Breitner C. Further investigations of bone changes resulting from experimental orthodontic treatment. Am J Orthod Oral Surg 1941;27:605-32. 4. Mongini F. Modificazioni dell’articolazione temporo-mandibolares nell’edentulismo parziale. Minerva Stomatol 1968;17: 850-8. 5. Mongini F. L’articolazione temporo-mandibolare nel morso profondo e nel morso incrociato. Minerva Stomatol 1968;17: 903-8. 6. Mongini F. Remodelling of the mandibular condyle in the adult and its relationship to the condition of the dental arches. Acta Anat 1972;82:437-53. 7. Mongini F. Dental abrasion as a factor in remodeling of the mandibular condyle. Acta Anat 1975;92:292-300. 8. Mongini F. Anatomic and clinical evaluation of the relationship between the temporomandibular joint and occlusion. J Prosthet Dent 1977;38:539-51. 9. Blackwood HJJ. Pathology of the temporomandibular joint. J Am Dent Assoc 1969;79:118-24. 10. Wedel A, Carlsson G, Sagne S. Temporomandibular joint morphology in a medieval skull material. Swed Dent J 1978;2:177-87. 11. Granados JI. The influence of the loss of teeth and attrition on the articular eminence. J Prosthet Dent 1979;42:78-85. 12. Richards JL, Brown T. Dental attrition and degenerative arthritis of the temporomandibular joint. J Oral Rehabil 1981;8:293-307. 13. O’Ryan F, Epker BN. Temporomandibular joint function and morphology: observations on the spectra of normalcy. Oral Surg 1984;58:272-9. 14. Matsumoto MAN, Bolognese AM. Bone morphology of the temporomandibular joint and its relation to dental occlusion. Braz Dent J 1995;6:115-22. 15. Burley MA. An examination of the relation between the radiographic appearance of the temporomandibular joint and some features of the occlusion. Br Dent J 1961;110:195-200.
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