- Email: [email protected]
Correlation of mandibular deviation with temporomandibular joint MR dimensions, MR disk position, and clinical symptoms
Correlation of mandibular deviation with temporomandibular joint MR dimensions, MR disk position, and clinical symptoms Tazuko K. Goto, DDS, PhD,a Satoko Nishida, BA,b Eiji Nakayama, DDS, PhD,c Yasuhiko Nakamura, RT,d Shuji Sakai, MD, PhD,e Hidetake Yabuuchi, MD, PhD,f and Kazunori Yoshiura, DDS, PhD,g Fukuoka, Japan KYUSHU UNIVERSITY AND KYUSHU UNIVERSITY HOSPITAL
Objective. The objective of this study was to investigate the difference of the temporomandibular joint (TMJ) between deviated and nondeviated sides of the mandible in adult patients with mandibular deviation.
Study design. TMJ size, disk displacement, and clinical symptoms of 28 patients were examined clinically and by magnetic resonance imaging (MRI). Twelve age- and sex-matched control subjects were also used to evaluate which side of the mandible in patients was similar to the control. Results. The TMJ on the deviated side showed a smaller condyle and a higher incidence of disk displacement than the nondeviated side and those in the controls. However, the clinical symptoms showed no differences between the deviated and nondeviated sides, and no association with disk displacement. Conclusions. Our results suggest that the deviated side was the abnormal side and may have some association with mandibular deviation. However, the clinical symptoms could not indicate those differences. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:743-9)
Patients with a mandibular deviation who have a lateral shift in the midline of the mandible may show asymmetric temporomandibular joint (TMJ) conditions because of the asymmetry of the shape of the face and occlusion. However, actual differences such as condyle
We are grateful to Ms Tomomi Yamada, Department of Medical Information Science, Kyushu University Hospital, and Prof Masashi Sugisaki, Department of Dentistry, Jikei University School of Medicine, for expert statistical advice. We also thank radiological technologists, Department of Radiology, Kyushu University Hospital, for their support for MR examinations. This study was supported by Grants in Aid of Scientific Research from the Ministry of Education, Japan (No. 16591887) and the Kyusyu University Foundation. a Assistant Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. b Research Assistant, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. c Associate Professor, Department of Oral and Maxillofacial Radiology, Kyushu University Hospital, Fukuoka, Japan. d Radiological Technologist, Department of Radiology, Kyushu University Hospital, Fukuoka, Japan. e Associate Professor, Department of Health Sciences, School of Medicine, Kyushu University, Fukuoka, Japan. f Assistant Professor, Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. g Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. Received for publication Feb 15, 2005; returned for revision May 7, 2005; accepted for publication May 18, 2005. 1079-2104/$ - see front matter Ó 2005 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2005.05.063
size, disk displacement, and clinical symptoms of temporomandibular disorder (TMD) between the deviated and nondeviated side of the mandible remain obscure. The anterior-posterior width of the condyle on the deviated side has been shown, using lateral images, to be smaller than that in the nondeviated side in patients with mandibular deviation.1,2 However, so far no studies have shown medio-lateral diameters (mm) of condyle that have associations with TMD3,4; furthermore, no studies of the area (mm2) of condyle have been performed. Anterior disk displacements have been seen mostly in the deviated side of the mandible in patients with mandibular deviation.1,5 Other articles have shown that in mandibular prognathism with asymmetry there is a higher incidence of disk displacement on both sides (56.8% and 66.7%),6,7 whereas little displacement is seen in patients with simple mandibular prognathism (18.2%).6 TMD may be associated with disturbed facial skeleton growth such as mandibular deviation in rabbits8 or in humans.9-11 Clinical signs and symptoms of TMD in patients with mandibular asymmetry have a high prevalence (35.3% to 85.7%).5-7,12-14 In addition, skeletal Class III with asymmetry always shows a higher incidence of TMD than without asymmetry.5,6 However, it is unknown whether there is any difference in TMJ symptoms between the deviated and nondeviated sides. We hypothesized that there may be differences in TMJ between the deviated and nondeviated sides of the mandible in adult patients with mandibular deviation 743
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Fig 1. Measurement of the horizontal diameter of the temporomandibular joint condyle. The medio-lateral diameter of each condyle was measured between the medial (M) and lateral (L) poles of the condyle on its medio-lateral axis. A line was drawn through the M and L on the condyle. The parallel line to the M-L lines was drawn to intersect the anterior edge and posterior edge of the condyle. The distance between A and P in a direction perpendicular to the medio-lateral axis of the condyle was measured as the antero-posterior diameter.
undergoing orthognathic surgery. The deviated side may be the abnormal side, and the nondeviated side might show similarities with controls. The purpose of this study was to investigate (1) the difference in TMJ size, disk displacement, and clinical symptoms between the deviated and nondeviated sides of the mandible and (2) whether the clinical symptoms reflect those differences and whether they can indicate disk displacement without diagnostic imaging in mandibular deviation cases. MATERIALS AND METHODS Subjects The study was carried out in 28 patients with mandibular deviation, 17 females and 11 males. Their age at the time of examination ranged from 17 to 34 years old. Their mandibular deviation was not due to dentition, so they are planning to undergo orthognathic surgery. Both the left and the right sides of the condyle on each patient were analyzed. All subjects had a lateral deviation of the mandible, with the deviation between the midline of the upper and lower incisors ranging from 3 to 11 mm (mean 5.8 mm). No cases of trauma, condylar hyperplasia, or congenital craniofacial syndrome were included. None of the subjects had any history of orthodontics. As controls, 12 adults (6 females and 6 males, 20 to 30 years old) were investigated. All subjects had a normal skull shape, normal occlusion, well-arranged dentitions, and no signs of craniofacial anomalies or TMD. Informed consent, which was reviewed and approved by the Ethics Committee of the Faculty of Dentistry, Kyushu University, was obtained from each of the subjects before the study.
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Condylar size measurements MRI studies were performed with a 1.5-tesla system (Magnetom Vision, Siemens AG, Erlangen, Germany). The axial images, which were used to measure the horizontal condylar head size, were obtained from highquality, 3-dimensional image sets by means of 3-dimensional magnetization-prepared rapid gradient-echo imaging (3D MP RAGE; TR 9.7 ms, TE 4.0 ms, TI 300 ms) in both groups of patients and control subjects. The data were analyzed using imaging-processing software (NIH image 1.62, National Institutes of Health, Bethesda, Md) on a Power Macintosh G4 (Apple Computer, Inc, Tokyo, Japan). The images were displayed as a series of contiguous axial images (pixel size 0.45 3 0.45 mm) at intervals of 1 mm. The outlines of the condyles were traced, and the areas of the condyles were measured on the computer monitor on each axial section. The maximum area of each condyle was employed for analysis. In addition, we measured the medio-lateral diameter of each condyle between the medial and lateral poles of the condyle on its medio-lateral axis. The anteroposterior diameters of the condyle were measured as the maximum distances between the extreme anterior and posterior points of the condyle in a direction perpendicular to the medio-lateral axis of the condyle (Fig 1). The ratio of the medio-lateral diameter to the antero-posterior diameter was then calculated. Statistical analysis At first, the sizes of the condyles were compared between the joints on the deviated side and nondeviated side of the mandible in patients. Statistical analyses were conducted with paired t test. The size of the condyle on each side for each patient was compared with that from controls to determine which side was similar to the controls. The mean data of the right and left sides were used as the data from each control subject because there was no difference between the right and left sides. With respect to the patient group, we selected 22 from 28 patients using random sampling (11 females and 11 males, 16 to 28 [mean 21.3] years of age, so that the ratio of female and male would be 1:1). We used t test and multiple comparison (Bonferroni’s method) to determine the differences between each side of the patients and controls. A level of P \ .05 was considered to be significant. Disk displacements Disk displacement was investigated using MRI with a head coil. An initial axial localizer that was parallel to the Frankfort horizontal plane and could maximally visualize the lateral and medial poles of both condyles was obtained. Oblique sagittal images of the TMJ
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(TR 2000 ms, TE 15 ms, FOV 15 cm, 3-mm section thickness) were then obtained at the closed- and opened-mouth positions. The subjects were asked to clench their teeth slightly on their intercuspal position at the closed-mouth position. At the maximum openedmouth positions, the subjects were instructed first to open their mouths as far as possible and then slightly decrease the degree of mouth opening to avoid discomfort while maintaining a maximum opening. Acrylic plastic blocks were placed in their mouths during the imaging process. The degree of disk displacement was classified as a normal disk position or anterior disk displacement at both the closed- and opened-mouth positions according to the criteria15-18 in the oblique sagittal images. The results of the lateral disk shifting are very often hazardous. Therefore, we did not evaluate them to simplify the presentation of the results. All MR images were evaluated separately by 2 specialists in maxillofacial radiology, blind to the deviation side of the mandible, TMJ symptoms, or any other information on the patients. As well as the one single image, all of the oblique sagittal MR images were assessed for disk displacement. Final assessments were carried out from a consensus of both radiologists. Clinical TMJ symptoms TMJ symptoms such as pain and joint sounds (clicking and crepitus) were clinically evaluated by the same trained examiner. The spontaneous pain and pain on mandibular movements were assessed by careful questioning and palpation. The joint sounds were determined by careful questioning and listening by the examiner. Palpation over the joints to detect the irregularity in the condylar path was also performed. RESULTS Size of the condyle Difference between the deviated and nondeviated sides of the mandible. The area and the medio-lateral diameter of the condyle of the deviated side were significantly smaller than that of the nondeviated side of the mandible. In particular, the medio-lateral diameter of the deviated side showed a larger standard deviation than the nondeviated side. However, the antero-posterior diameter, the ratio of the medio-lateral diameter to the antero-posterior diameter, showed no significant differences between the deviated and nondeviated sides (Table I). Differences between each side of the patients and controls. The area and the medio-lateral diameter of the condyle of the deviated side were significantly smaller than that of the controls, whereas the nondeviated side of the mandible did not show any significant difference
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Table I. Size of the condyle in patients with mandibular deviation Deviated side (n = 28) Mean 6 SD Area (mm2) Medio-lateral diameter (mm) Antero-posterior diameter (mm) Ratio of ML to AP* (ML/AP)
Nondeviated side (n = 28) Mean 6 SD
120.1 6 29.5 147.7 6 28.8 P \ .0001 16.8 6 2.9 18.3 6 2.0 P \ .0045 8.0 6 1.5 8.5 6 1.5 NS 2.2 6 0.6 2.2 6 0.4 NS
*Ratio of medio-lateral diameter to antero-posterior diameter.
to the controls. The nondeviated sides were similar to the controls. On the other hand, the antero-posterior diameter, the ratio of the medio-lateral diameter to the antero-posterior diameter, showed no significant differences between the patients and controls (Fig 2). Disk displacement The disk displacement at the closed-mouth position is shown in Table II. Anterior disk displacements can be seen more on the deviated side (64.3%) than on the nondeviated side (25.0%). At the opened-mouth position (Table III), 8 (28.6%) TMJ disks showed without reduction and they were seen on the deviated side only. All 28 disks showed the normal position in the nondeviated side at the opened-mouth position. Clinical TMJ symptoms TMJ pain was found in 2 joints from the deviated side only. TMJ sound was diagnosed clinically in 21 (37.5%) joints, and these showed almost the same incidence on both the deviated and nondeviated sides (11 joints and 10 joints, respectively; see Table IV). The association between TMJ sound and disk displacement is shown in Table V. On the deviated side, even if the TMJ showed no sound clinically, 39.3% of joints showed disk displacement. On the nondeviated side, 50% of joints showed no TMJ sound clinically and no disk displacement, whereas 14.3% of joints showed disk displacement even with no sound. From the results, no definite association was found between TMJ sound and disk displacement. DISCUSSION This study documents, for the first time, the differences in horizontal TMJ condyle size between the mandibular deviated and nondeviated sides in young adults with mandibular deviation undergoing orthognathic surgery. The medio-lateral diameters (mm) of the condyle that have some association with TMD,3,4
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Table II. Comparisons of disk position between the deviated and nondeviated sides of patients at the closed-mouth position (n = 56 joints in total) Disk position (no. of joints) Normal (31) Anterior disk displacement (25)
Deviated side (n = 28)
Nondeviated side (n = 28)
10 (35.7%) 18 (64.3%)
21 (75.0%) 7 (25.0%)
Table III. Comparisons of disk position between deviated and nondeviated sides of patients at the opened-mouth position (n = 56 joints in total) Disk position at closed-mouth position (no. of joints)
Disk position at opened-mouth position
Deviated side (n = 28)
Normal (31) Normal 10 (35.7%) Anterior disk With reduction 10 (35.7%) displacement (25) Without reduction 8 (28.6%)
Nondeviated side (n = 28) 21 (75.0%) 7 (25.0%) 0 (0.0%)
Table IV. Clinical signs and symptoms in patients with mandibular deviation (n = 56 in total, n = 28 joints in each side of the mandible) TMJ pain, n (%) TMJ sound, n (%)
Click Crepitus
Deviated side
Nondeviated side
2 (7.1) 10 (35.7) 1 (3.6)
0 9 (32.1) 1 (3.6)
furthermore, the area (mm2) of condyle, have been unknown in such patients. For this purpose, axial MR images were used to measure the horizontal condyle size. We investigated the contiguous axial MR images at 1-mm intervals, so that the axial image would be representative of the entire condylar head. By using the sequence of 3D MP RAGE for TMJ, we were able to evaluate the size and shape of the condyle in more detail than previous studies, without any excessive physical burden or cost to the patients. Our results clearly showed that the TMJ condyle of the deviated side of the mandible was the abnormal side. The deviated side showed a smaller condyle and a higher incidence of disk displacement than the nondeviated side. In addition, the deviated side was
Fig 2. Comparison of the size of the condyle between each side of the patients and controls. Means and standard deviations are shown. A, Maximum area of the condyle (mm2). B, Medio-lateral diameter. C, Antero-posterior diameter. D, Ratio of medio-lateral diameter to antero-posterior diameter. *P \.05 with Bonferroni method.
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Table V. Clinical TMJ sound and disk displacement at the closed-mouth position in patients with mandibular deviation Deviated side (n = 28) Disk displacement
No TMJ sound, n (%) TMJ sound, n (%)
Nondeviated side (n = 28) Disk displacement
Total of both sides (n = 56) Disk displacement
No (n = 10)
Yes (n = 18)
No (n = 21)
Yes (n = 7)
No (n = 31)
Yes (n = 25)
6 (21.4) 4 (14.3)
11 (39.3) 7 (25.0)
14 (50.0) 7 (25.0)
4 (14.3) 3 (10.7)
20 (35.7) 11 (19.6)
15 (26.8) 10 (17.9)
significantly smaller than the control. Our study was performed in the age- and sex-matched patients and controls. Therefore, our results provide a valuable reference for examination of patients with mandibular deviation. Association between condylar size and TMD In patients with TMD (no information about jaw deformity), the condyle had a smaller medio-lateral diameter with resorption of the lateral pole of the condyle in accordance with advancement of internal derangement.3,4 Comparing each side of the patients and controls in our study, the area and the medio-lateral diameter of the condyle from the deviated side was significantly smaller, whereas the size of the condyle from the nondeviated side was similar to that of the controls. Our results suggest that there is a possible association between TMD and a small condyle size, especially in terms of the area and the medio-lateral diameter. On the other hand, there were no differences in antero-posterior diameter for the deviated and nondeviated sides in our study. Also, in other studies of TMD patients, the antero-posterior diameter showed no correlation with the radiological stage of internal derangement,4 or resorption of the lateral pole the condyle.19 These suggest that any association between antero-posterior diameter and TMD might be minor. Association between condylar size and mandibular deviation TMD is the principal cause of both acquired facial skeleton remodeling and unstable occlusion in patients with intact dentition.20 The condyle on the deviated side was smaller and more deformed than on the nondeviated side in 6 patients with a mandibular deviation on the transpharyngeal radiographs.1 From previous laminography results reported by Akahane et al,2 the anteriorposterior width of the condyle in the asymmetry class III was found to be smaller on the shifted side than on the unshifted side of the mandible. Our study showed different results because of the methods used. Previous studies have measured the antero-posterior diameter by visual comparison, or using a different level of condyle using x-ray images in the lateral direction, and therefore
direct comparisons are difficult. Previous results, however, suggested that the deviated side is different from the nondeviated side, and there may be some possible association between condylar size and mandibular deviation. In our study, the area and the medio-lateral diameter of the condyle of the deviated side were significantly smaller, whereas the condylar size of the nondeviated side was similar to that of controls. Our results suggest there is a possible association between condyle size and mandibular deviation. The mean of the ratio of the medio-lateral/anteroposterior diameter in our patients was the same in both the deviated and nondeviated sides. However, the shape of the condyle of the deviated side showed large variations (eg, concave, round, and flat; see Fig 3). Our results suggest that the ratio of the medio-lateral/ antero-posterior diameter could not explain the variation in condylar shape in mandibular deviation cases; it is important also to make qualitative observations from axial images. Association between disk displacement and mandibular deviation Link and Nickerson1 showed that all 6 patients with a mandibular deviation had anterior disk displacement without reduction. Kobayashi et al5 demonstrated that no disks were displaced in patients with a simple mandibular prognathism, but 15 (58%) of 26 patients with mandibular prognathism and asymmetry had displaced disks, and in 14 (93%) of the 15 patients disk displacement was seen on the deviated side. Interestingly, Ueki et al6 reported mandibular prognathism with asymmetry showed a higher incidence of disk displacement (56.8%), whereas few displacements were seen in patients with simple prognathism (18.2%). Our results clearly showed that anterior disk displacements are seen more on the deviated side than on the nondeviated side. At opened-mouth positions, all of the nonreduced disks were seen only on the deviated side, whereas reduction was seen on the nondeviated side. These results suggest that disk displacement may be associated with the skeletal morphology, and mandibular deviation has a stronger association with TMD than simple mandibular prognathism.
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mandibular asymmetry; several other factors also come into play. Can clinical symptoms act as an index of disk displacement or mandibular deviation? Patients with mandibular deviation have a high incidence of TMD symptoms.5-7,12-14 When comparing the skeletal Class III with asymmetry and without asymmetry, Class III with asymmetry always shows a higher incidence of TMD.5,6 These previous results show that asymmetry cases probably show a higher incidence of TMJ symptoms. However, other studies have concluded that there is no correlation between TMJ signs and symptoms and disk displacement.5,22,23 Patients with disk displacement do not always have signs and symptoms of TMJ dysfunction, and patients with symptoms did not always have disk displacement. Our results also showed no clear correlation between clinical TMJ sound and disk displacement. Twenty-one (37.5%) joints showed TMJ sound, and the sound occurred not only on the deviated side but also on the nondeviated sides. Eleven (39.3%) joints showed disk displacement on the deviated side, although they showed no TMJ sound clinically. These results suggest that it is difficult to diagnose TMD with associated mandibular deviation from clinical symptoms only.
Fig 3. Examples of axial images of the condyles. The deviated side showed a wide variation in shape, eg, concave, flat, and round.
Isberg21 concluded that inductions of craniofacial growth changes include anterior and posterior condylar functioning, trauma, ankylosis, coronoid process impingement, disk displacement, disease destroying the condyle growth site, and systemic disease. Nonreducing disk displacement during growth has been found to be associated with mandibular asymmetry with a midline shift to the ipsilateral side in rabbits8 and in adult humans.11 These previous results suggest that there is an association between TMD and mandibular deviation, especially on the deviated side. We should focus on TMD in the younger generation because some young TMD patients may develop mandibular deviation during puberty. In our study, meanwhile, 35.7% of TMJ on the deviated side showed no TMJ disk displacement. Therefore, we should also take into account that disk displacement is not always an etiological factor in
CONCLUSION TMJ on the deviated side of the mandible in patients with mandibular deviation was characterized by a smaller condyle and higher incidence of disk displacement than on the nondeviated side, and these differ from the controls. It is assumed that the area and mediolateral diameter of the condyle predicted mandibular deviation and/or TMD, whereas the antero-posterior diameter did not. The ratio of the medio-lateral diameter/antero-posterior diameter could not represent the condylar shape in mandibular deviation cases, thus suggesting that it is also important to evaluate the shape qualitatively in each patient. Our results suggest that it is important to pay attention to TMJ in mandibular deviation cases, especially on the deviated side. However, no association was found between clinical symptoms and disk displacement, so it is important to include an objective examination such as MRI, which can help determine the morphology of bone and the disk of the condyles in each patient with no radiation hazard to the patient. REFERENCES 1. Link JJ, Nickerson JW Jr. Temporomandibular joint internal derangements in an orthognathic surgery population. Int J Adult Orthodon Orthognath Surg 1992;7:161-9. 2. Akahane Y, Deguchi T, Hunt NP. Morphology of the temporomandibular joint in skeletal class III symmetrical and asymmetrical
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cases: a study by cephalometric laminography. J Orthod 2001;28: 119-27. Kurita H, Ohtsuka A, Kobayashi H, Kurashina K. Resorption of the lateral pole of the temporomandibular condyle in temporomandibular disc displacement. Dentomaxillofac Radiol 2001;30: 88-91. Kurita H, Ohtsuka A, Kobayashi H, Kurashina K. Alteration of the horizontal mandibular condyle size associated with temporomandibular joint internal derangement in adult females. Dentomaxillofac Radiol 2002;31:373-8. Kobayashi T, Honma K, Izumi K, Hayashi T, Shingaki S, Nakajima T. Temporomandibular joint symptoms and disc displacement in patients with mandibular prognathism. Br J Oral Maxillofac Surg 1999;37:455-8. Ueki K, Nakagawa K, Takatsuka S, Shimada M, Marukawa K, Takazakura D, et al. Temporomandibular joint morphology and disc position in skeletal class III patients. J Craniomaxillofac Surg 2000;28:362-8. Yamada K, Hanada K, Hayashi T, Ito J. Condylar bony change, disk displacement, and signs and symptoms of TMJ disorders in orthognathic surgery patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;91:603-10. Legrell PE, Isberg A. Mandibular length and midline asymmetry after experimentally induced temporomandibular joint disk displacement in rabbits. Am J Orthod Dentofac Orthop 1999; 115:247-53. Schellhas KP, Pollei SR, Wilkes CH. Pediatric internal derangements of the temporomandibular joint: effect on facial development. Am J Orthod Dentofac Orthop 1993;104:51-9. Trpkova B, Major P, Nebbe B, Prasad N. Craniofacial asymmetry and temporomandibular joint internal derangement in female adolescents: a posteroanterior cephalometric study. Angle Orthod 2000;70:81-8. Isberg A, Legrell PE. Facial asymmetry in adults following temporomandibular joint disc displacement with onset during growth. World J Orthod 2000;1:164-72. Karabouta I, Martis C. The TMJ dysfunction syndrome before and after sagittal split osteotomy of the rami. J Maxillofac Surg 1985;13:185-8. Kerstens HCJ, Tuinzing DB, van der Kwast WAM. Temporomandibular joint symptoms in orthognathic surgery. J Craniomaxillofac Surg 1989;17:215-8.
Goto et al 749 14. White CS, Dolwick MF. Prevalence and variance of temporomandibular dysfunction in orthognathic surgery patients. Int J Adult Orthodon Orthognath Surg 1992;7:7-14. 15. Roberts D, Schenck J, Joseph P, Foster T, Hart H, Pettigrew J, et al. Temporomandibular joint: magnetic resonance imaging. Radiology 1985;155:829-30. 16. Helms CA, Gillespy T 3rd, Sims RE, Richardson ML. Magnetic resonance imaging of internal derangement of the temporomandibular joint. Radiol Clin North Am 1986;24:189-92. 17. Katzberg RW. Temporomandibular joint imaging. Radiology 1989;170:297-307. 18. Drace JE, Enzmann DR. Defining the normal temporomandibular joint: closed-, partially open-, and open-mouth MR imaging of asymptomatic subjects. Radiology 1990;177:67-71. 19. Kurita H, Koike T, Narikawa J, Nakatsuka A, Kobayashi H, Kurashina K. Relationship between alteration of horizontal size and bony morphological change in the mandibular condyle. Dentomaxillofac Radiol 2003;32:355-8. 20. Schellhas KP, Piper MA, Omlie MR. Facial skeleton remodeling due to temporomandibular joint degeneration: an imaging study of 100 patients. Am J Roentgenol 1990;155:373-83. 21. Isberg A. Growth changes. In: Isberg A, ed. Temporomandibular joint dysfunction: a practitioner’s guide. London, UK: Taylor & Francis; 2001. p. 145-58. 22. Dahlberg G, Petersson A, Westesson PL, Eriksson L. Disk displacement and temporomandibular joint symptoms in orthognathic surgery patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:273-7. 23. Westesson PL, Eriksson L, Kurita K. Reliability of a negative clinical temporomandibular joint examination: prevalence of disk displacement in asymptomatic temporomandibular joints. Oral Surg Oral Med Oral Pathol 1989;68:551-4. Reprint requests: Tazuko K. Goto, DDS, PhD Department of Oral and Maxillofacial Radiology Faculty of Dental Science, Kyushu University 3-1-1, Maidashi, Higashi-ku Fukuoka 812-8582, Japan [email protected]
Objective. The objective of this study was to investigate the difference of the temporomandibular joint (TMJ) between deviated and nondeviated sides of the mandible in adult patients with mandibular deviation.
Study design. TMJ size, disk displacement, and clinical symptoms of 28 patients were examined clinically and by magnetic resonance imaging (MRI). Twelve age- and sex-matched control subjects were also used to evaluate which side of the mandible in patients was similar to the control. Results. The TMJ on the deviated side showed a smaller condyle and a higher incidence of disk displacement than the nondeviated side and those in the controls. However, the clinical symptoms showed no differences between the deviated and nondeviated sides, and no association with disk displacement. Conclusions. Our results suggest that the deviated side was the abnormal side and may have some association with mandibular deviation. However, the clinical symptoms could not indicate those differences. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:743-9)
Patients with a mandibular deviation who have a lateral shift in the midline of the mandible may show asymmetric temporomandibular joint (TMJ) conditions because of the asymmetry of the shape of the face and occlusion. However, actual differences such as condyle
We are grateful to Ms Tomomi Yamada, Department of Medical Information Science, Kyushu University Hospital, and Prof Masashi Sugisaki, Department of Dentistry, Jikei University School of Medicine, for expert statistical advice. We also thank radiological technologists, Department of Radiology, Kyushu University Hospital, for their support for MR examinations. This study was supported by Grants in Aid of Scientific Research from the Ministry of Education, Japan (No. 16591887) and the Kyusyu University Foundation. a Assistant Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. b Research Assistant, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. c Associate Professor, Department of Oral and Maxillofacial Radiology, Kyushu University Hospital, Fukuoka, Japan. d Radiological Technologist, Department of Radiology, Kyushu University Hospital, Fukuoka, Japan. e Associate Professor, Department of Health Sciences, School of Medicine, Kyushu University, Fukuoka, Japan. f Assistant Professor, Department of Clinical Radiology, Graduate School of Medical Sciences, Kyushu University, Fukuoka, Japan. g Professor, Department of Oral and Maxillofacial Radiology, Faculty of Dental Science, Kyushu University, Fukuoka, Japan. Received for publication Feb 15, 2005; returned for revision May 7, 2005; accepted for publication May 18, 2005. 1079-2104/$ - see front matter Ó 2005 Mosby, Inc. All rights reserved. doi:10.1016/j.tripleo.2005.05.063
size, disk displacement, and clinical symptoms of temporomandibular disorder (TMD) between the deviated and nondeviated side of the mandible remain obscure. The anterior-posterior width of the condyle on the deviated side has been shown, using lateral images, to be smaller than that in the nondeviated side in patients with mandibular deviation.1,2 However, so far no studies have shown medio-lateral diameters (mm) of condyle that have associations with TMD3,4; furthermore, no studies of the area (mm2) of condyle have been performed. Anterior disk displacements have been seen mostly in the deviated side of the mandible in patients with mandibular deviation.1,5 Other articles have shown that in mandibular prognathism with asymmetry there is a higher incidence of disk displacement on both sides (56.8% and 66.7%),6,7 whereas little displacement is seen in patients with simple mandibular prognathism (18.2%).6 TMD may be associated with disturbed facial skeleton growth such as mandibular deviation in rabbits8 or in humans.9-11 Clinical signs and symptoms of TMD in patients with mandibular asymmetry have a high prevalence (35.3% to 85.7%).5-7,12-14 In addition, skeletal Class III with asymmetry always shows a higher incidence of TMD than without asymmetry.5,6 However, it is unknown whether there is any difference in TMJ symptoms between the deviated and nondeviated sides. We hypothesized that there may be differences in TMJ between the deviated and nondeviated sides of the mandible in adult patients with mandibular deviation 743
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Fig 1. Measurement of the horizontal diameter of the temporomandibular joint condyle. The medio-lateral diameter of each condyle was measured between the medial (M) and lateral (L) poles of the condyle on its medio-lateral axis. A line was drawn through the M and L on the condyle. The parallel line to the M-L lines was drawn to intersect the anterior edge and posterior edge of the condyle. The distance between A and P in a direction perpendicular to the medio-lateral axis of the condyle was measured as the antero-posterior diameter.
undergoing orthognathic surgery. The deviated side may be the abnormal side, and the nondeviated side might show similarities with controls. The purpose of this study was to investigate (1) the difference in TMJ size, disk displacement, and clinical symptoms between the deviated and nondeviated sides of the mandible and (2) whether the clinical symptoms reflect those differences and whether they can indicate disk displacement without diagnostic imaging in mandibular deviation cases. MATERIALS AND METHODS Subjects The study was carried out in 28 patients with mandibular deviation, 17 females and 11 males. Their age at the time of examination ranged from 17 to 34 years old. Their mandibular deviation was not due to dentition, so they are planning to undergo orthognathic surgery. Both the left and the right sides of the condyle on each patient were analyzed. All subjects had a lateral deviation of the mandible, with the deviation between the midline of the upper and lower incisors ranging from 3 to 11 mm (mean 5.8 mm). No cases of trauma, condylar hyperplasia, or congenital craniofacial syndrome were included. None of the subjects had any history of orthodontics. As controls, 12 adults (6 females and 6 males, 20 to 30 years old) were investigated. All subjects had a normal skull shape, normal occlusion, well-arranged dentitions, and no signs of craniofacial anomalies or TMD. Informed consent, which was reviewed and approved by the Ethics Committee of the Faculty of Dentistry, Kyushu University, was obtained from each of the subjects before the study.
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Condylar size measurements MRI studies were performed with a 1.5-tesla system (Magnetom Vision, Siemens AG, Erlangen, Germany). The axial images, which were used to measure the horizontal condylar head size, were obtained from highquality, 3-dimensional image sets by means of 3-dimensional magnetization-prepared rapid gradient-echo imaging (3D MP RAGE; TR 9.7 ms, TE 4.0 ms, TI 300 ms) in both groups of patients and control subjects. The data were analyzed using imaging-processing software (NIH image 1.62, National Institutes of Health, Bethesda, Md) on a Power Macintosh G4 (Apple Computer, Inc, Tokyo, Japan). The images were displayed as a series of contiguous axial images (pixel size 0.45 3 0.45 mm) at intervals of 1 mm. The outlines of the condyles were traced, and the areas of the condyles were measured on the computer monitor on each axial section. The maximum area of each condyle was employed for analysis. In addition, we measured the medio-lateral diameter of each condyle between the medial and lateral poles of the condyle on its medio-lateral axis. The anteroposterior diameters of the condyle were measured as the maximum distances between the extreme anterior and posterior points of the condyle in a direction perpendicular to the medio-lateral axis of the condyle (Fig 1). The ratio of the medio-lateral diameter to the antero-posterior diameter was then calculated. Statistical analysis At first, the sizes of the condyles were compared between the joints on the deviated side and nondeviated side of the mandible in patients. Statistical analyses were conducted with paired t test. The size of the condyle on each side for each patient was compared with that from controls to determine which side was similar to the controls. The mean data of the right and left sides were used as the data from each control subject because there was no difference between the right and left sides. With respect to the patient group, we selected 22 from 28 patients using random sampling (11 females and 11 males, 16 to 28 [mean 21.3] years of age, so that the ratio of female and male would be 1:1). We used t test and multiple comparison (Bonferroni’s method) to determine the differences between each side of the patients and controls. A level of P \ .05 was considered to be significant. Disk displacements Disk displacement was investigated using MRI with a head coil. An initial axial localizer that was parallel to the Frankfort horizontal plane and could maximally visualize the lateral and medial poles of both condyles was obtained. Oblique sagittal images of the TMJ
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(TR 2000 ms, TE 15 ms, FOV 15 cm, 3-mm section thickness) were then obtained at the closed- and opened-mouth positions. The subjects were asked to clench their teeth slightly on their intercuspal position at the closed-mouth position. At the maximum openedmouth positions, the subjects were instructed first to open their mouths as far as possible and then slightly decrease the degree of mouth opening to avoid discomfort while maintaining a maximum opening. Acrylic plastic blocks were placed in their mouths during the imaging process. The degree of disk displacement was classified as a normal disk position or anterior disk displacement at both the closed- and opened-mouth positions according to the criteria15-18 in the oblique sagittal images. The results of the lateral disk shifting are very often hazardous. Therefore, we did not evaluate them to simplify the presentation of the results. All MR images were evaluated separately by 2 specialists in maxillofacial radiology, blind to the deviation side of the mandible, TMJ symptoms, or any other information on the patients. As well as the one single image, all of the oblique sagittal MR images were assessed for disk displacement. Final assessments were carried out from a consensus of both radiologists. Clinical TMJ symptoms TMJ symptoms such as pain and joint sounds (clicking and crepitus) were clinically evaluated by the same trained examiner. The spontaneous pain and pain on mandibular movements were assessed by careful questioning and palpation. The joint sounds were determined by careful questioning and listening by the examiner. Palpation over the joints to detect the irregularity in the condylar path was also performed. RESULTS Size of the condyle Difference between the deviated and nondeviated sides of the mandible. The area and the medio-lateral diameter of the condyle of the deviated side were significantly smaller than that of the nondeviated side of the mandible. In particular, the medio-lateral diameter of the deviated side showed a larger standard deviation than the nondeviated side. However, the antero-posterior diameter, the ratio of the medio-lateral diameter to the antero-posterior diameter, showed no significant differences between the deviated and nondeviated sides (Table I). Differences between each side of the patients and controls. The area and the medio-lateral diameter of the condyle of the deviated side were significantly smaller than that of the controls, whereas the nondeviated side of the mandible did not show any significant difference
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Table I. Size of the condyle in patients with mandibular deviation Deviated side (n = 28) Mean 6 SD Area (mm2) Medio-lateral diameter (mm) Antero-posterior diameter (mm) Ratio of ML to AP* (ML/AP)
Nondeviated side (n = 28) Mean 6 SD
120.1 6 29.5 147.7 6 28.8 P \ .0001 16.8 6 2.9 18.3 6 2.0 P \ .0045 8.0 6 1.5 8.5 6 1.5 NS 2.2 6 0.6 2.2 6 0.4 NS
*Ratio of medio-lateral diameter to antero-posterior diameter.
to the controls. The nondeviated sides were similar to the controls. On the other hand, the antero-posterior diameter, the ratio of the medio-lateral diameter to the antero-posterior diameter, showed no significant differences between the patients and controls (Fig 2). Disk displacement The disk displacement at the closed-mouth position is shown in Table II. Anterior disk displacements can be seen more on the deviated side (64.3%) than on the nondeviated side (25.0%). At the opened-mouth position (Table III), 8 (28.6%) TMJ disks showed without reduction and they were seen on the deviated side only. All 28 disks showed the normal position in the nondeviated side at the opened-mouth position. Clinical TMJ symptoms TMJ pain was found in 2 joints from the deviated side only. TMJ sound was diagnosed clinically in 21 (37.5%) joints, and these showed almost the same incidence on both the deviated and nondeviated sides (11 joints and 10 joints, respectively; see Table IV). The association between TMJ sound and disk displacement is shown in Table V. On the deviated side, even if the TMJ showed no sound clinically, 39.3% of joints showed disk displacement. On the nondeviated side, 50% of joints showed no TMJ sound clinically and no disk displacement, whereas 14.3% of joints showed disk displacement even with no sound. From the results, no definite association was found between TMJ sound and disk displacement. DISCUSSION This study documents, for the first time, the differences in horizontal TMJ condyle size between the mandibular deviated and nondeviated sides in young adults with mandibular deviation undergoing orthognathic surgery. The medio-lateral diameters (mm) of the condyle that have some association with TMD,3,4
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Table II. Comparisons of disk position between the deviated and nondeviated sides of patients at the closed-mouth position (n = 56 joints in total) Disk position (no. of joints) Normal (31) Anterior disk displacement (25)
Deviated side (n = 28)
Nondeviated side (n = 28)
10 (35.7%) 18 (64.3%)
21 (75.0%) 7 (25.0%)
Table III. Comparisons of disk position between deviated and nondeviated sides of patients at the opened-mouth position (n = 56 joints in total) Disk position at closed-mouth position (no. of joints)
Disk position at opened-mouth position
Deviated side (n = 28)
Normal (31) Normal 10 (35.7%) Anterior disk With reduction 10 (35.7%) displacement (25) Without reduction 8 (28.6%)
Nondeviated side (n = 28) 21 (75.0%) 7 (25.0%) 0 (0.0%)
Table IV. Clinical signs and symptoms in patients with mandibular deviation (n = 56 in total, n = 28 joints in each side of the mandible) TMJ pain, n (%) TMJ sound, n (%)
Click Crepitus
Deviated side
Nondeviated side
2 (7.1) 10 (35.7) 1 (3.6)
0 9 (32.1) 1 (3.6)
furthermore, the area (mm2) of condyle, have been unknown in such patients. For this purpose, axial MR images were used to measure the horizontal condyle size. We investigated the contiguous axial MR images at 1-mm intervals, so that the axial image would be representative of the entire condylar head. By using the sequence of 3D MP RAGE for TMJ, we were able to evaluate the size and shape of the condyle in more detail than previous studies, without any excessive physical burden or cost to the patients. Our results clearly showed that the TMJ condyle of the deviated side of the mandible was the abnormal side. The deviated side showed a smaller condyle and a higher incidence of disk displacement than the nondeviated side. In addition, the deviated side was
Fig 2. Comparison of the size of the condyle between each side of the patients and controls. Means and standard deviations are shown. A, Maximum area of the condyle (mm2). B, Medio-lateral diameter. C, Antero-posterior diameter. D, Ratio of medio-lateral diameter to antero-posterior diameter. *P \.05 with Bonferroni method.
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Table V. Clinical TMJ sound and disk displacement at the closed-mouth position in patients with mandibular deviation Deviated side (n = 28) Disk displacement
No TMJ sound, n (%) TMJ sound, n (%)
Nondeviated side (n = 28) Disk displacement
Total of both sides (n = 56) Disk displacement
No (n = 10)
Yes (n = 18)
No (n = 21)
Yes (n = 7)
No (n = 31)
Yes (n = 25)
6 (21.4) 4 (14.3)
11 (39.3) 7 (25.0)
14 (50.0) 7 (25.0)
4 (14.3) 3 (10.7)
20 (35.7) 11 (19.6)
15 (26.8) 10 (17.9)
significantly smaller than the control. Our study was performed in the age- and sex-matched patients and controls. Therefore, our results provide a valuable reference for examination of patients with mandibular deviation. Association between condylar size and TMD In patients with TMD (no information about jaw deformity), the condyle had a smaller medio-lateral diameter with resorption of the lateral pole of the condyle in accordance with advancement of internal derangement.3,4 Comparing each side of the patients and controls in our study, the area and the medio-lateral diameter of the condyle from the deviated side was significantly smaller, whereas the size of the condyle from the nondeviated side was similar to that of the controls. Our results suggest that there is a possible association between TMD and a small condyle size, especially in terms of the area and the medio-lateral diameter. On the other hand, there were no differences in antero-posterior diameter for the deviated and nondeviated sides in our study. Also, in other studies of TMD patients, the antero-posterior diameter showed no correlation with the radiological stage of internal derangement,4 or resorption of the lateral pole the condyle.19 These suggest that any association between antero-posterior diameter and TMD might be minor. Association between condylar size and mandibular deviation TMD is the principal cause of both acquired facial skeleton remodeling and unstable occlusion in patients with intact dentition.20 The condyle on the deviated side was smaller and more deformed than on the nondeviated side in 6 patients with a mandibular deviation on the transpharyngeal radiographs.1 From previous laminography results reported by Akahane et al,2 the anteriorposterior width of the condyle in the asymmetry class III was found to be smaller on the shifted side than on the unshifted side of the mandible. Our study showed different results because of the methods used. Previous studies have measured the antero-posterior diameter by visual comparison, or using a different level of condyle using x-ray images in the lateral direction, and therefore
direct comparisons are difficult. Previous results, however, suggested that the deviated side is different from the nondeviated side, and there may be some possible association between condylar size and mandibular deviation. In our study, the area and the medio-lateral diameter of the condyle of the deviated side were significantly smaller, whereas the condylar size of the nondeviated side was similar to that of controls. Our results suggest there is a possible association between condyle size and mandibular deviation. The mean of the ratio of the medio-lateral/anteroposterior diameter in our patients was the same in both the deviated and nondeviated sides. However, the shape of the condyle of the deviated side showed large variations (eg, concave, round, and flat; see Fig 3). Our results suggest that the ratio of the medio-lateral/ antero-posterior diameter could not explain the variation in condylar shape in mandibular deviation cases; it is important also to make qualitative observations from axial images. Association between disk displacement and mandibular deviation Link and Nickerson1 showed that all 6 patients with a mandibular deviation had anterior disk displacement without reduction. Kobayashi et al5 demonstrated that no disks were displaced in patients with a simple mandibular prognathism, but 15 (58%) of 26 patients with mandibular prognathism and asymmetry had displaced disks, and in 14 (93%) of the 15 patients disk displacement was seen on the deviated side. Interestingly, Ueki et al6 reported mandibular prognathism with asymmetry showed a higher incidence of disk displacement (56.8%), whereas few displacements were seen in patients with simple prognathism (18.2%). Our results clearly showed that anterior disk displacements are seen more on the deviated side than on the nondeviated side. At opened-mouth positions, all of the nonreduced disks were seen only on the deviated side, whereas reduction was seen on the nondeviated side. These results suggest that disk displacement may be associated with the skeletal morphology, and mandibular deviation has a stronger association with TMD than simple mandibular prognathism.
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mandibular asymmetry; several other factors also come into play. Can clinical symptoms act as an index of disk displacement or mandibular deviation? Patients with mandibular deviation have a high incidence of TMD symptoms.5-7,12-14 When comparing the skeletal Class III with asymmetry and without asymmetry, Class III with asymmetry always shows a higher incidence of TMD.5,6 These previous results show that asymmetry cases probably show a higher incidence of TMJ symptoms. However, other studies have concluded that there is no correlation between TMJ signs and symptoms and disk displacement.5,22,23 Patients with disk displacement do not always have signs and symptoms of TMJ dysfunction, and patients with symptoms did not always have disk displacement. Our results also showed no clear correlation between clinical TMJ sound and disk displacement. Twenty-one (37.5%) joints showed TMJ sound, and the sound occurred not only on the deviated side but also on the nondeviated sides. Eleven (39.3%) joints showed disk displacement on the deviated side, although they showed no TMJ sound clinically. These results suggest that it is difficult to diagnose TMD with associated mandibular deviation from clinical symptoms only.
Fig 3. Examples of axial images of the condyles. The deviated side showed a wide variation in shape, eg, concave, flat, and round.
Isberg21 concluded that inductions of craniofacial growth changes include anterior and posterior condylar functioning, trauma, ankylosis, coronoid process impingement, disk displacement, disease destroying the condyle growth site, and systemic disease. Nonreducing disk displacement during growth has been found to be associated with mandibular asymmetry with a midline shift to the ipsilateral side in rabbits8 and in adult humans.11 These previous results suggest that there is an association between TMD and mandibular deviation, especially on the deviated side. We should focus on TMD in the younger generation because some young TMD patients may develop mandibular deviation during puberty. In our study, meanwhile, 35.7% of TMJ on the deviated side showed no TMJ disk displacement. Therefore, we should also take into account that disk displacement is not always an etiological factor in
CONCLUSION TMJ on the deviated side of the mandible in patients with mandibular deviation was characterized by a smaller condyle and higher incidence of disk displacement than on the nondeviated side, and these differ from the controls. It is assumed that the area and mediolateral diameter of the condyle predicted mandibular deviation and/or TMD, whereas the antero-posterior diameter did not. The ratio of the medio-lateral diameter/antero-posterior diameter could not represent the condylar shape in mandibular deviation cases, thus suggesting that it is also important to evaluate the shape qualitatively in each patient. Our results suggest that it is important to pay attention to TMJ in mandibular deviation cases, especially on the deviated side. However, no association was found between clinical symptoms and disk displacement, so it is important to include an objective examination such as MRI, which can help determine the morphology of bone and the disk of the condyles in each patient with no radiation hazard to the patient. REFERENCES 1. Link JJ, Nickerson JW Jr. Temporomandibular joint internal derangements in an orthognathic surgery population. Int J Adult Orthodon Orthognath Surg 1992;7:161-9. 2. Akahane Y, Deguchi T, Hunt NP. Morphology of the temporomandibular joint in skeletal class III symmetrical and asymmetrical
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cases: a study by cephalometric laminography. J Orthod 2001;28: 119-27. Kurita H, Ohtsuka A, Kobayashi H, Kurashina K. Resorption of the lateral pole of the temporomandibular condyle in temporomandibular disc displacement. Dentomaxillofac Radiol 2001;30: 88-91. Kurita H, Ohtsuka A, Kobayashi H, Kurashina K. Alteration of the horizontal mandibular condyle size associated with temporomandibular joint internal derangement in adult females. Dentomaxillofac Radiol 2002;31:373-8. Kobayashi T, Honma K, Izumi K, Hayashi T, Shingaki S, Nakajima T. Temporomandibular joint symptoms and disc displacement in patients with mandibular prognathism. Br J Oral Maxillofac Surg 1999;37:455-8. Ueki K, Nakagawa K, Takatsuka S, Shimada M, Marukawa K, Takazakura D, et al. Temporomandibular joint morphology and disc position in skeletal class III patients. J Craniomaxillofac Surg 2000;28:362-8. Yamada K, Hanada K, Hayashi T, Ito J. Condylar bony change, disk displacement, and signs and symptoms of TMJ disorders in orthognathic surgery patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2001;91:603-10. Legrell PE, Isberg A. Mandibular length and midline asymmetry after experimentally induced temporomandibular joint disk displacement in rabbits. Am J Orthod Dentofac Orthop 1999; 115:247-53. Schellhas KP, Pollei SR, Wilkes CH. Pediatric internal derangements of the temporomandibular joint: effect on facial development. Am J Orthod Dentofac Orthop 1993;104:51-9. Trpkova B, Major P, Nebbe B, Prasad N. Craniofacial asymmetry and temporomandibular joint internal derangement in female adolescents: a posteroanterior cephalometric study. Angle Orthod 2000;70:81-8. Isberg A, Legrell PE. Facial asymmetry in adults following temporomandibular joint disc displacement with onset during growth. World J Orthod 2000;1:164-72. Karabouta I, Martis C. The TMJ dysfunction syndrome before and after sagittal split osteotomy of the rami. J Maxillofac Surg 1985;13:185-8. Kerstens HCJ, Tuinzing DB, van der Kwast WAM. Temporomandibular joint symptoms in orthognathic surgery. J Craniomaxillofac Surg 1989;17:215-8.
Goto et al 749 14. White CS, Dolwick MF. Prevalence and variance of temporomandibular dysfunction in orthognathic surgery patients. Int J Adult Orthodon Orthognath Surg 1992;7:7-14. 15. Roberts D, Schenck J, Joseph P, Foster T, Hart H, Pettigrew J, et al. Temporomandibular joint: magnetic resonance imaging. Radiology 1985;155:829-30. 16. Helms CA, Gillespy T 3rd, Sims RE, Richardson ML. Magnetic resonance imaging of internal derangement of the temporomandibular joint. Radiol Clin North Am 1986;24:189-92. 17. Katzberg RW. Temporomandibular joint imaging. Radiology 1989;170:297-307. 18. Drace JE, Enzmann DR. Defining the normal temporomandibular joint: closed-, partially open-, and open-mouth MR imaging of asymptomatic subjects. Radiology 1990;177:67-71. 19. Kurita H, Koike T, Narikawa J, Nakatsuka A, Kobayashi H, Kurashina K. Relationship between alteration of horizontal size and bony morphological change in the mandibular condyle. Dentomaxillofac Radiol 2003;32:355-8. 20. Schellhas KP, Piper MA, Omlie MR. Facial skeleton remodeling due to temporomandibular joint degeneration: an imaging study of 100 patients. Am J Roentgenol 1990;155:373-83. 21. Isberg A. Growth changes. In: Isberg A, ed. Temporomandibular joint dysfunction: a practitioner’s guide. London, UK: Taylor & Francis; 2001. p. 145-58. 22. Dahlberg G, Petersson A, Westesson PL, Eriksson L. Disk displacement and temporomandibular joint symptoms in orthognathic surgery patients. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 1995;79:273-7. 23. Westesson PL, Eriksson L, Kurita K. Reliability of a negative clinical temporomandibular joint examination: prevalence of disk displacement in asymptomatic temporomandibular joints. Oral Surg Oral Med Oral Pathol 1989;68:551-4. Reprint requests: Tazuko K. Goto, DDS, PhD Department of Oral and Maxillofacial Radiology Faculty of Dental Science, Kyushu University 3-1-1, Maidashi, Higashi-ku Fukuoka 812-8582, Japan [email protected]