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Improvement of asymmetric stomatognathic functions, unilateral crossbite, and facial esthetics in a patient with skeletal Class III malocclusion and mandibular asymmetry, treated with orthognathic surgery
CASE REPORT
Improvement of asymmetric stomatognathic functions, unilateral crossbite, and facial esthetics in a patient with skeletal Class III malocclusion and mandibular asymmetry, treated with orthognathic surgery Nobuo Takeshita,a Masahiko Ishida,b Hisako Watanabe,c Takashi Hashimoto,c Takayoshi Daimaruya,c Masakazu Hasegawa,d and Teruko Takano-Yamamotoe Sendai, Japan
Patients with a dentofacial skeletal deformity have not only esthetic and morphologic problems related to facial proportions and dentition, but also problems of stomatognathic functions. Therefore, in addition to morphologic analysis, functional analysis is important for the diagnosis and evaluation of treatment in these patients. However, no reports have described longitudinal simultaneous evaluations of stomatognathic functions, and the comprehensive effects of surgical orthodontics on the stomatognathic functions are unclear. A patient was diagnosed as having a skeletal Class III jaw-base relationship, mandibular asymmetry, unilateral crossbite, asymmetric stomatognathic functions, and a temporomandibular disorder. She was treated with a combination of surgery and orthodontic therapy. As a result, facial proportions and occlusion improved; in particular, asymmetric stomatognathic functions, including masticatory muscle activity, condylar movement, and occlusal force, became symmetric between the left and right sides. Moreover, after 2 years of retention, the activity of the masticatory muscles and the values of occlusal force and occlusal contact area exceeded those at pretreatment. These results suggest that improvement of asymmetric stomatognathic functions can be achieved by correction of dentofacial morphology by surgical orthodontic treatment in patients with mandibular asymmetry. (Am J Orthod Dentofacial Orthop 2013;144:441-54)
P
atients with a dentofacial skeletal deformity have not only esthetic and morphologic problems related to facial proportions and the dentition, but also problems of stomatognathic functions, such as masticatory muscle activity, mandibular and condylar movement, and occlusal force.1-7 Therefore, in addition From the Division of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Tohoku University, Sendai, Japan. a Assistant professor. b Postgraduate student. c Adjunct assistant professor. d Instructor. e Professor and chair. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Reprint requests to: Teruko Takano-Yamamoto, Division of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai City, Miyagi 980-8575, Japan; e-mail, [email protected]. Submitted, revised and accepted, September 2012. 0889-5406/$36.00 Copyright Ó 2013 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2012.09.024
to morphologic analysis, functional analysis is important for the diagnosis and evaluation of treatment results in these patients. Some previous case reports presented findings of stomatognathic function. Maeda et al8 and Nakajima et al9 reported improvement of electromyographic activity of the masseter and temporalis muscles in surgical orthodontic cases with maxillary and mandibular prognathism, respectively. Furthermore, orthognathic surgery for patients with unilateral crossbite and occlusal cant resulted in correction of asymmetric incisal and condylar paths using a 6 degrees of freedom jaw movement recording system.10,11 However, although masticatory muscle activity, occlusal force, and condylar movement are all important factors for normal stomatognathic function, they were only individually evaluated in previous case reports, and the comprehensive effects of surgical orthodontics on stomatognathic function is unclear. The prevalence of temporomandibular disorder (TMD) symptoms, such as joint sounds and pain, limited 441
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Fig 1. Pretreatment facial and intraoral photographs.
opening of the mouth, and articular disc displacement, was found to be higher in patients with mandibular prognathism and mandibular asymmetry than in those without mandibular asymmetry.12,13 In contrast, Goto et al14 reported that although the temporomandibular joint (TMJ) on the deviated side showed a higher incidence of disc displacement in patients with mandibular asymmetry, clinical TMD symptoms showed no difference between the deviated and nondeviated sides. On the other hand, it has been reported that TMD symptoms can be improved by orthognathic surgery in patients Therefore, with mandibular prognathism.10,15 diagnosis and posttreatment evaluation of the TMJ are important for patients with mandibular asymmetry and prognathism treated by orthognathic surgery. Magnetic resonance imaging is useful to make a diagnosis of the TMJ because of its capacity to evaluate the
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soft and hard tissues without physical invasion. Anteroposterior and transverse disc displacements are diagnosed by sagittal and coronal magnetic resonance images, respectively. However, the transverse disc position in patients with mandibular asymmetry is not well known. This case report describes a skeletal Class III patient with mandibular asymmetry and unilateral crossbite treated by a combination of surgery and orthodontic therapy. For the first time, we longitudinally evaluated changes of occlusion, skeletal morphology, and stomatognathic functions such as masticatory muscle activity, occlusal force, condylar movement, and anteroposterior and transverse disc positions. As a result, it was suggested that the improvement of asymmetric stomatognathic functions can be achieved by correction of dentofacial morphology by surgical orthodontics in patients with mandibular asymmetry.
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Fig 2. Pretreatment dental casts.
Fig 3. Pretreatment cephalometric and panoramic radiographs.
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Table I. Cephalometric summary Japanese norm (adult) Measurement Angular ( ) SNA SNB ANB Mp-SN Gonial angle U1-SN L1-FH L1-Mp IIA Linear (mm) S-N N-Me Me/NF Ans-Ptm/NF Go-Me Ar-Go Ar-Me Overjet Overbite
Mean
SD
Pretreatment
Posttreatment
Postretention
80.8 77.9 2.8 37.1 122.1 105.9 56.0 93.4 123.6
3.6 4.5 2.4 4.6 5.3 8.8 8.1 6.8 10.6
82.3 82.9 0.6 34.6 130.1 107.7 61.3 90.4 127.3
82.3 80.8 1.6 37.4 132.2 106.1 60.0 89.2 127.3
82.2 80.6 1.6 37.1 132.6 106.5 60.0 89.0 127.4
67.9 125.8 68.6 52.1 71.4 47.3 106.6 3.1 3.3
3.7 5.0 3.7 3.0 4.1 3.3 5.7 1.1 1.9
75.0 130.6 71.8 59.3 78.4 49.9 118.7 2.6 1.2
74.7 129.4 70.8 59.6 76.3 47.6 115.3 1.7 1.2
74.6 129.6 70.7 59.7 76.2 47.5 115.0 1.5 1.3
Means and standard deviations from Wada et al.31
Fig 4. Electromyographic recordings of masticatory muscles. Ta, Anterior temporalis muscle; Mm, masseter muscle; Tp, posterior temporalis muscle. DIAGNOSIS AND ETIOLOGY
A young woman, age 18 years 8 months, came to the outpatient clinic of Tohoku University Hospital in Japan. Her chief complaints were mandibular protrusion and facial asymmetry. The facial photographs showed a mandibular deviation toward the right and a concave profile (Fig 1). The mandibular dental midline was deviated 3.5 mm toward the right compared with the
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maxilla, and she had anterior and right posterior crossbites (Figs 1 and 2). The molar relationships were Class III on both sides. Overjet and overbite were –1.5 and 2 mm, respectively (Figs 1 and 2). A panoramic radiograph showed that all third molars were impacted (Fig 3). The cephalometric analysis showed a skeletal Class III jawbase relationship, an average mandibular plane angle, and normal inclinations of the maxillary and mandibular
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Fig 5. Occlusal force and occlusal contact area recordings (1 represents the center of the occlusal force): A, pretreatment; B, posttreatment; C, postretention. Rt, Right side; Lt, left side.
Table II. Occlusal force and occlusal contact area Pretreatment
Occlusal force (N) % Occlusal contact area (mm2) %
Total 735.2 100 17.1 100
Right 475.7 64.7 10.6 62.0
Posttreatment Left 259.5 35.3 6.5 38.0
Total 518.2 100 11.3 100
Right 263.4 50.8 5.9 51.9
Postretention Left 254.8 49.2 5.4 48.1
Total 837.3 100 23.4 100
Right 422.0 50.4 12.4 52.9
Left 415.3 49.6 11.0 47.1
Fig 6. Sagittal view of condylar movement during 6 degrees of freedom jaw movement recording.
anterior teeth (Fig 3, Table I). The posteroanterior cephalogram showed a mandibular deviation toward the right of 4 mm. Electromyographic monitoring showed that activities of the masseter and anterior and posterior temporalis muscles were lower during unilateral chewing on the
left side than on the right side (Fig 4). During tapping, the masseter muscle was mainly activated on the right side; in contrast, the posterior temporalis muscle was mainly activated on the left side. An occlusal-force recording system showed higher values of occlusal force and occlusal contact area on the right side than on the
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Table III. Condylar path length during jaw movements Condylar path length (mm) Maximum open-close Right Left Laterotrusion Right Left Protrusion Right Left
Pretreatment
Posttreatment
Postretention
12.8 11.5
16.4 11.2
17.2 15.6
11.2 6.9
8.5 9.0
9.8 9.7
7.2 5.9
10.6 12.1
11.0 11.8
Fig 7. Magnetic resonance images: A-D, I-L, and Q-T, sagittal planes; E-H, M-P, and U-X, coronal planes. Arrows show disc positions: a, Anterior side; p, posterior side; m, mesial side; l, lateral side.
left (Fig 5, A; Table II). A 6 degrees of freedom jaw movement recording system showed that condylar path length was shorter on the left side than on the right during lateral and protrusive jaw movements (Fig 6, Table III). Manipulation of the TMJ elicited clicking sounds on the left side. The sagittal magnetic resonance images showed anterior articular disc displacement with reduction on the right TMJ (Fig 7, A and C). In contrast, a normal disc position was shown on the left side (Fig 7, B and D). The coronal magnetic resonance images did not show a transverse displacement of the disc on the right side (Fig 7, E and G). On the left side, lateral displacement of the anterior band of the disc was shown in the closed-mouth position, but not in the openmouth position (Fig 7, F and H).
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TREATMENT OBJECTIVES
The patient was diagnosed as having a skeletal Class III jaw-base relationship, mandibular asymmetry, unilateral crossbite, asymmetric stomatognathic functions, and TMD. The treatment objectives were to correct the skeletal deformity, obtain an ideal occlusion, and improve the asymmetric stomatognathic functions by a combination of surgery and orthodontic therapy. We planned to perform presurgical orthodontic treatment focused on maintaining normal inclinations of the maxillary and mandibular incisors to obtain an ideal incisor relationship after surgery. A bilateral sagittal split ramus osteotomy was planned to correct the mandibular asymmetry
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Fig 8. Posttreatment facial and intraoral photographs.
and the protrusion after the improvement of the asymmetric stomatognathic function. The impacted mandibular right and left third molars were to be extracted before surgery so as not to interfere with the surgical procedures.
expected that asymmetric stomatognathic functions could be improved in patients with mandibular asymmetry by orthognathic surgery.17,18 Therefore, we decided to perform a combination of surgery and orthodontic therapy to improve both dentofacial morphology and stomatognathic functions.
TREATMENT ALTERNATIVES
Because it is possible to achieve a good treatment outcome using miniscrew anchorage in patients with a skeletal discrepancy, orthodontic camouflage with miniscrew anchorage could be a treatment alternative to correct the anterior and unilateral crossbites in our patient.16 However, it could not sufficiently correct the mandibular protrusion and the facial asymmetry, which were the patient’s chief complaints. Furthermore, it was
TREATMENT PROGRESS
After checking the oral hygiene status and giving toothbrushing instructions, we placed 0.018 3 0.025-in preadjusted edgewise appliances on the maxillary and mandibular dental arches, and leveling and alignment were started with 0.016-in and 0.014-in nickel-titanium archwires for the maxilla and mandible, respectively. Subsequently, tooth alignment proceeded by changing the
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Fig 9. Posttreatment dental casts.
Fig 10. Posttreatment cephalometric and panoramic radiographs.
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Fig 11. Superimposed pretreatment (solid line) and posttreatment (dotted line) cephalometric tracings: A, on the sella-nasion plane at sella; B, on the palatal plane at ANS; C, on the mandibular plane at menton.
archwires sequentially, and 0.016 3 0.022-in stainless steel archwires were used to adjust the tooth positions just before surgery. Both mandibular third molars were extracted 5 months before surgery, and the extraction sockets were cured by bone formation at the time of surgery. After presurgical orthodontic treatment for 1 year 4 months, a sagittal split ramus osteotomy was performed. The mandible was set back 2 mm on the right side and 5.5 mm on the left side. Postsurgical orthodontic treatment was performed for 7 months. The occlusion was detailed using 0.017 3 0.025-in beta-titanium archwires, and then the edgewise appliances were removed. The duration of active treatment was 2 years 1 month. Retention was started with Begg-type retainers, and the patient was followed for 2 years. TREATMENT RESULTS
As a result of the setback and the transverse rotation of the mandible by the sagittal split ramus osteotomy, the mandibular protrusion and the asymmetry were corrected, and facial esthetics were improved (Fig 8). The anterior and right posterior crossbites were corrected, and the mandibular midline was coincident with the maxillary midline (Figs 8 and 9). Class I canine and molar relationships were obtained. The posttreatment panoramic radiograph showed no remarkable apical root
resorption or alveolar bone loss (Fig 10). The posttreatment cephalometric analysis showed that a skeletal Class I jaw relationship had been achieved (Figs 10 and 11, Table I). Clear changes of the maxillary and mandibular incisor inclinations were not shown, indicating that the normal incisor inclinations were maintained (Figs 10 and 11, Table I). A posteroanterior cephalogram showed that the mandibular midline coincided with the facial midline (Fig 10). A posttreatment electromyographic recording showed no remarkable differences of the activity of the masseter and the anterior and posterior temporalis muscles during unilateral chewing on the left and right sides (Fig 4). During tapping, activities of these masticatory muscles were balanced on the 2 sides (Fig 4). However, activity of the masticatory muscles decreased during clenching (Fig 4). Occlusal force and occlusal contact area showed almost the same values on the left and right sides, although each value decreased compared with the values before treatment (Fig 5, B; Table II). The 6 degrees of freedom jaw movement recording system showed an increase of the right condylar path length during maximum mouth opening and closing (Fig 6, Table III). The asymmetric condylar path lengths during lateral and protrusive jaw movements were improved (Fig 6, Table III). In addition, the condylar path lengths on
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Fig 12. Postretention facial and intraoral photographs.
both sides increased during protrusive jaw movements (Fig 6, Table III). The clicking sounds still remained, and the sagittal and coronal magnetic resonance images showed no clear changes of articular disc positions (Fig 7, I-P). After 2 years of retention, an acceptable facial profile and occlusion were maintained (Figs 12-15, Table I). The symmetric masticatory muscle activities were also maintained (Fig 4). Moreover, they were increased during tapping and clenching compared with those at posttreatment. The occlusal force and occlusal contact area increased during the retention phase, and they showed higher values than before treatment (Fig 5, C; Table II). The left condylar path length during maximum mouth opening and closing increased; consequently, the difference of condylar path length between the right and
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left sides shown just after active treatment was corrected (Fig 6, Table III). The symmetric condylar path lengths during lateral and protrusive jaw movements were maintained. Although the disc displacement and the clicking sounds still remained in the TMJ, they have not worsened (Fig 7, Q-X). DISCUSSION
Patients with mandibular asymmetry and unilateral crossbite have asymmetric activity of masticatory muscles.3,19 Asymmetry of muscle size and orientation, and a difference of myosin heavy chain composition between the right and left sides might be associated with the asymmetric activity of the masticatory muscles in these patients.20,21 Sforza et al17 reported that orthognathic surgery for a mandibular
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Fig 13. Postretention dental casts.
Fig 14. Postretention cephalometric and panoramic radiographs.
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Fig 15. Superimposed posttreatment (solid line) and postretention (dotted line) cephalometric tracings: A, on the sella-nasion plane at sella; B, on the palatal plane at ANS; C, on the mandibular plane at menton.
prognathism patient with mandibular asymmetry resulted in improvement of the asymmetric activity of the masticatory muscles. In our patient, activities of the masseter and anterior and posterior temporalis muscles were lower during unilateral chewing on the left side than on the right side before treatment. Furthermore, the masseter muscle and the posterior temporalis muscle were mainly activated on the right and the left sides during tapping, respectively. These results indicated asymmetric activity of the masticatory muscles in this patient. On the other hand, the posttreatment electromyographic recording showed symmetric activities of the masticatory muscles during unilateral chewing and tapping, and these results suggest that this patient obtained balanced masticatory muscle activity by surgical orthodontics. It is known that occlusal force and occlusal contact area are greater on the deviated side than on the nondeviated side in patients with mandibular asymmetry.7 However, the effects of surgical orthodontics on the asymmetry of occlusal force and occlusal contact area are unclear. In this patient, occlusal force and occlusal contact area were greater on the deviated side than on the nondeviated side before treatment. On the other hand, they were balanced between the 2 sides after postsurgical orthodontic therapy. These results suggest the possibility of correcting the asymmetry of occlusal force and
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occlusal contact area by surgical orthodontics in patients with mandibular asymmetry. The effects of orthognathic surgery on masticatory muscle activity and occlusal force have been individually reported.22,23 However, there have been no reports regarding simultaneous longitudinal assessments of masticatory muscle activity, occlusal force, and occlusal contact area in a surgical orthodontic patient. In our patient, asymmetric masticatory muscle activity, occlusal force, and occlusal contact area were corrected after active treatment, and the obtained symmetric stomatognathic functions were maintained during the retention phase. Moreover, although the activity of the masticatory muscles and the values of occlusal force and occlusal contact area decreased after active treatment, they increased during retention and showed higher activity and values than before treatment. These results indicate the long-term stability of balanced stomatognathic function obtained by orthognathic surgery in a patient with mandibular asymmetry. Furthermore, it is suggested that stomatognathic function decreases just after active treatment, but it recovers and subsequently exceeds the pretreatment values during the retention phase, possibly in correlation with masticatory muscle activity, occlusal force, and occlusal contact area in surgical orthodontic patients.
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In patients with mandibular deviation, condylar path length on the deviated side was longer than on the nondeviated side during mouth opening and closing, and lateral and protrusive jaw movements.5,6 Not only skeletal discrepancy but also asymmetric condylar movement can be corrected by orthognathic surgery for patients with mandibular asymmetry.11,18 In this patient, condylar path length on the nondeviated side was shorter than on the deviated side during lateral and protrusive jaw movements before treatment. The asymmetric condylar path length was corrected after active treatment, mainly because of an increase of condylar path length on the nondeviated side. These results are consistent with previous reports.5,6,11,18 However, the relationships between condylar movement and masticatory muscle activity have been unclear. In this patient, improvements of asymmetric condylar movement and masticatory muscle activity were shown after active treatment. Because jaw movement is directly regulated by the contraction of the masticatory muscles, it is speculated that skeletal correction by orthognathic surgery resulted in improvement of asymmetric masticatory muscle activity, followed by improvement of asymmetric condylar movement.24 Moreover, little is known about the change of the condylar path length during the retention phase in patients who undergo orthognathic surgery. In this patient, condylar path length on both sides during maximum mouth opening and closing increased during the retention phase. The inferior head of the lateral pterygoid muscle regulates the anterior movement of the condyle during mouth opening.25 Because activities of the masseter muscle and the anterior and posterior temporalis muscles increased during the retention phase in this patient, it is possible that activity of the lateral pterygoid muscle also increased and contributed to the increase of the condylar path length. It has been reported that there is a close relationship between mandibular asymmetry and TMD.12,13,26 It is important to make a diagnosis of TMD before orthodontic treatment of patients with mandibular asymmetry. Disc displacement, which is a form of TMD, is often diagnosed by analysis of the anteroposterior disc position with sagittal magnetic resonance images. However, coronal magnetic resonance images are needed to diagnose transverse displacement and rotation of the disc.27 In this patient, the coronal magnetic resonance images showed lateral displacement of the anterior band of the disc on the nondeviated side in the closed-mouth position, but no displacement in the open-mouth position. These results suggest lateral disc displacement with reduction on the nondeviated side. A common cause of clicking in the
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TMJ is disc displacement with reduction.28 Therefore, the clicking sound on the nondeviated side in this patient might have been due to the reduction of the lateral disc displacement. In addition, anterior disc displacement is frequently seen on the deviated side in patients with mandibular asymmetry.12,29 Anterior disc displacement with reduction was observed on the deviated side in our patient. Because overload of the TMJ can be a cause of disc displacement, it is suggested that asymmetric occlusal force and masticatory muscle activity lead to overload of the TMJ on the deviated side and then cause anterior disc displacement.30 It has been reported that an intraoral ramus osteotomy can improve anterior disc displacement.10 However, little is known about the effect of orthognathic surgery on transverse disc displacement. Although there were no clear changes of the lateral disc displacement after the sagittal split ramus osteotomy in this patient, further study is needed to clarify the effect of orthognathic surgery on transverse disc position by evaluating coronal magnetic resonance images. CONCLUSIONS
Longitudinal simultaneous evaluation of stomatognathic function was performed as well as analysis of dentofacial morphology for a skeletal Class III patient with mandibular asymmetry. As a result of the evaluation, it was indicated for the first time that surgical orthodontics could comprehensively improve asymmetric stomatognathic functions including masticatory muscle activity, condylar movement, and occlusal force. In addition, with sagittal and coronal magnetic resonance images, we could evaluate the 3-dimensional position of the articular disc, and it was shown that although the articular disc displacements were not corrected, at least no worsening of these displacements occurred after surgery in this patient. This case report demonstrates the importance of analysis of stomatognathic function and the TMJ as well as dentofacial morphology to make a diagnosis and to evaluate the treatment outcome in a patient with a dentofacial skeletal deformity. REFERENCES 1. Kobayashi T, Honma K, Shingaki S, Nakajima T. Changes in masticatory function after orthognathic treatment in patients with mandibular prognathism. Br J Oral Maxillofac Surg 2001;39: 260-5. 2. Deguchi T, Garetto LP, Sato Y, Potter RH, Roberts WE. Statistical analysis of differential lissajous EMG from normal occlusion and Class III malocclusion. Angle Orthod 1995;65:151-60. 3. Dong Y, Wang XM, Wang MQ, Widmalm SE. Asymmetric muscle function in patients with developmental mandibular asymmetry. J Oral Rehabil 2008;35:27-36.
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4. Wang D, Fu H, Zeng R, Yang X. Changes of mandibular movement tracings after the correction of mandibular protrusion by bilateral sagittal split ramus osteotomy. J Oral Maxillofac Surg 2009;67: 2238-44. 5. Oguri Y, Yamada K, Fukui T, Hanada K, Kohno S. Mandibular movement and frontal craniofacial morphology in orthognathic surgery patients with mandibular deviation and protrusion. J Oral Rehabil 2003;30:392-400. 6. Ishizaki K, Suzuki K, Mito T, Tanaka EM, Sato S. Morphologic, functional, and occlusal characterization of mandibular lateral displacement malocclusion. Am J Orthod Dentofacial Orthop 2010;137:454.e1-9. 7. Goto TK, Yamada T, Yoshiura K. Occlusal pressure, occlusal contact area, force and the correlation with the morphology of the jaw-closing muscles in patients with skeletal mandibular asymmetry. J Oral Rehabil 2008;35:594-603. 8. Maeda A, Soejima K, Ogura M, Ohmure H, Sugihara K, Miyawaki S. Orthodontic treatment combined with mandibular distraction osteogenesis and changes in stomatognathic function. Angle Orthod 2008;78:1125-32. 9. Nakajima K, Yamaguchi T, Maki K. Surgical orthodontic treatment for a patient with advanced periodontal disease: evaluation with electromyography and 3-dimensional conebeam computed tomography. Am J Orthod Dentofacial Orthop 2009;136:450-9. 10. Miyatake E, Miyawaki S, Morishige Y, Nishiyama A, Sasaki A, Takano-Yamamoto T. Class III malocclusion with severe facial asymmetry, unilateral posterior crossbite, and temporomandibular disorders. Am J Orthod Dentofacial Orthop 2003;124: 435-45. 11. Hashimoto T, Fukunaga T, Kuroda S, Sakai Y, Yamashiro T, Takano-Yamamoto T. Mandibular deviation and canted maxillary occlusal plane treated with miniscrews and intraoral vertical ramus osteotomy: functional and morphologic changes. Am J Orthod Dentofacial Orthop 2009;136:868-77. 12. 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. 13. 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. 14. Goto TK, Nishida S, Nakayama E, Nakamura Y, Sakai S, Yabuuchi H, et al. Correlation of mandibular deviation with temporomandibular joint MR dimensions, MR disk position, and clinical symptoms. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:743-9. 15. Hu J, Wang D, Zou S. Effects of mandibular setback on the temporomandibular joint: a comparison of oblique and sagittal split ramus osteotomy. J Oral Maxillofac Surg 2000; 58:375-80.
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16. Sakai Y, Kuroda S, Murshid SA, Takano-Yamamoto T. Skeletal Class III severe openbite treatment using implant anchorage. Angle Orthod 2008;78:157-66. 17. Sforza C, Peretta R, Grandi G, Ferronato G, Ferrario VF. Soft tissue facial planes and masticatory muscle function in skeletal Class III patients before and after orthognathic surgery treatment. J Oral Maxillofac Surg 2008;66:691-8. 18. Hashimoto T, Kuroda S, Lihua E, Tanimoto Y, Miyawaki S, TakanoYamamoto T. Correlation between craniofacial and condylar path asymmetry. J Oral Maxillofac Surg 2008;66:2020-7. 19. Matsumoto R, Ioi H, Goto TK, Hara A, Nakata S, Nakasima A, et al. Relationship between the unilateral TMJ osteoarthritis/osteoarthrosis, mandibular asymmetry and the EMG activity of the masticatory muscles: a retrospective study. J Oral Rehabil 2010; 37:85-92. 20. Goto TK, Nishida S, Yahagi M, Langenbach GE, Nakamura Y, Tokumori K, et al. Size and orientation of masticatory muscles in patients with mandibular laterognathism. J Dent Res 2006;85: 552-6. 21. Raoul G, Rowlerson A, Sciote J, Codaccioni E, Stevens L, Maurage CA, et al. Masseter myosin heavy chain composition varies with mandibular asymmetry. J Craniofac Surg 2011;22:1093-8. 22. Trawitzki LV, Dantas RO, Mello-Filho FV, Marques W Jr. Masticatory muscle function three years after surgical correction of Class III dentofacial deformity. Int J Oral Maxillofac Surg 2010;39: 853-6. 23. Kim YG, Oh SH. Effect of mandibular setback surgery on occlusal force. J Oral Maxillofac Surg 1997;55:121-6. 24. Greenfield BE, Wyke BD. Electromyographic studies of some of the muscles of mastication. Br Dent J 1956;100:129-43. 25. Ash MM Jr. Wheeler’s dental anatomy, physiology and occlusion. Philadelphia: W. B. Saunders; 1993. 26. 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. 27. Arat FE, Arat ZM, Tompson B, Tanju S. Muscular and condylar response to rapid maxillary expansion. Part 3: magnetic resonance assessment of condyle-disc relationship. Am J Orthod Dentofacial Orthop 2008;133:830-6. 28. Isberg A. Temporomandibular joint dysfunction: a practitioner’s guide. Oxford: Isis Medical Media; 2001. 29. Link JJ, Nickerson JW Jr. Temporomandibular joint internal derangements in an orthognathic surgery population. Int J Adult Orthod Orthognath Surg 1992;7:161-9. 30. Nitzan DW. The process of lubrication impairment and its involvement in temporomandibular joint disc displacement: a theoretical concept. J Oral Maxillofac Surg 2001;59:36-45. 31. Wada K, Matsushita K, Shimazaki S, Miwa Y, Hasuike Y, Susami R. An evaluation of a new case analysis of a lateral cphalometric roentgenogram. J Kanazawa Med Univ 1981;6: 60-70.
American Journal of Orthodontics and Dentofacial Orthopedics
Improvement of asymmetric stomatognathic functions, unilateral crossbite, and facial esthetics in a patient with skeletal Class III malocclusion and mandibular asymmetry, treated with orthognathic surgery Nobuo Takeshita,a Masahiko Ishida,b Hisako Watanabe,c Takashi Hashimoto,c Takayoshi Daimaruya,c Masakazu Hasegawa,d and Teruko Takano-Yamamotoe Sendai, Japan
Patients with a dentofacial skeletal deformity have not only esthetic and morphologic problems related to facial proportions and dentition, but also problems of stomatognathic functions. Therefore, in addition to morphologic analysis, functional analysis is important for the diagnosis and evaluation of treatment in these patients. However, no reports have described longitudinal simultaneous evaluations of stomatognathic functions, and the comprehensive effects of surgical orthodontics on the stomatognathic functions are unclear. A patient was diagnosed as having a skeletal Class III jaw-base relationship, mandibular asymmetry, unilateral crossbite, asymmetric stomatognathic functions, and a temporomandibular disorder. She was treated with a combination of surgery and orthodontic therapy. As a result, facial proportions and occlusion improved; in particular, asymmetric stomatognathic functions, including masticatory muscle activity, condylar movement, and occlusal force, became symmetric between the left and right sides. Moreover, after 2 years of retention, the activity of the masticatory muscles and the values of occlusal force and occlusal contact area exceeded those at pretreatment. These results suggest that improvement of asymmetric stomatognathic functions can be achieved by correction of dentofacial morphology by surgical orthodontic treatment in patients with mandibular asymmetry. (Am J Orthod Dentofacial Orthop 2013;144:441-54)
P
atients with a dentofacial skeletal deformity have not only esthetic and morphologic problems related to facial proportions and the dentition, but also problems of stomatognathic functions, such as masticatory muscle activity, mandibular and condylar movement, and occlusal force.1-7 Therefore, in addition From the Division of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Tohoku University, Sendai, Japan. a Assistant professor. b Postgraduate student. c Adjunct assistant professor. d Instructor. e Professor and chair. All authors have completed and submitted the ICMJE Form for Disclosure of Potential Conflicts of Interest, and none were reported. Reprint requests to: Teruko Takano-Yamamoto, Division of Orthodontics and Dentofacial Orthopedics, Graduate School of Dentistry, Tohoku University, 4-1 Seiryo-machi, Aoba-ku, Sendai City, Miyagi 980-8575, Japan; e-mail, [email protected]. Submitted, revised and accepted, September 2012. 0889-5406/$36.00 Copyright Ó 2013 by the American Association of Orthodontists. http://dx.doi.org/10.1016/j.ajodo.2012.09.024
to morphologic analysis, functional analysis is important for the diagnosis and evaluation of treatment results in these patients. Some previous case reports presented findings of stomatognathic function. Maeda et al8 and Nakajima et al9 reported improvement of electromyographic activity of the masseter and temporalis muscles in surgical orthodontic cases with maxillary and mandibular prognathism, respectively. Furthermore, orthognathic surgery for patients with unilateral crossbite and occlusal cant resulted in correction of asymmetric incisal and condylar paths using a 6 degrees of freedom jaw movement recording system.10,11 However, although masticatory muscle activity, occlusal force, and condylar movement are all important factors for normal stomatognathic function, they were only individually evaluated in previous case reports, and the comprehensive effects of surgical orthodontics on stomatognathic function is unclear. The prevalence of temporomandibular disorder (TMD) symptoms, such as joint sounds and pain, limited 441
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Fig 1. Pretreatment facial and intraoral photographs.
opening of the mouth, and articular disc displacement, was found to be higher in patients with mandibular prognathism and mandibular asymmetry than in those without mandibular asymmetry.12,13 In contrast, Goto et al14 reported that although the temporomandibular joint (TMJ) on the deviated side showed a higher incidence of disc displacement in patients with mandibular asymmetry, clinical TMD symptoms showed no difference between the deviated and nondeviated sides. On the other hand, it has been reported that TMD symptoms can be improved by orthognathic surgery in patients Therefore, with mandibular prognathism.10,15 diagnosis and posttreatment evaluation of the TMJ are important for patients with mandibular asymmetry and prognathism treated by orthognathic surgery. Magnetic resonance imaging is useful to make a diagnosis of the TMJ because of its capacity to evaluate the
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soft and hard tissues without physical invasion. Anteroposterior and transverse disc displacements are diagnosed by sagittal and coronal magnetic resonance images, respectively. However, the transverse disc position in patients with mandibular asymmetry is not well known. This case report describes a skeletal Class III patient with mandibular asymmetry and unilateral crossbite treated by a combination of surgery and orthodontic therapy. For the first time, we longitudinally evaluated changes of occlusion, skeletal morphology, and stomatognathic functions such as masticatory muscle activity, occlusal force, condylar movement, and anteroposterior and transverse disc positions. As a result, it was suggested that the improvement of asymmetric stomatognathic functions can be achieved by correction of dentofacial morphology by surgical orthodontics in patients with mandibular asymmetry.
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Fig 2. Pretreatment dental casts.
Fig 3. Pretreatment cephalometric and panoramic radiographs.
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Table I. Cephalometric summary Japanese norm (adult) Measurement Angular ( ) SNA SNB ANB Mp-SN Gonial angle U1-SN L1-FH L1-Mp IIA Linear (mm) S-N N-Me Me/NF Ans-Ptm/NF Go-Me Ar-Go Ar-Me Overjet Overbite
Mean
SD
Pretreatment
Posttreatment
Postretention
80.8 77.9 2.8 37.1 122.1 105.9 56.0 93.4 123.6
3.6 4.5 2.4 4.6 5.3 8.8 8.1 6.8 10.6
82.3 82.9 0.6 34.6 130.1 107.7 61.3 90.4 127.3
82.3 80.8 1.6 37.4 132.2 106.1 60.0 89.2 127.3
82.2 80.6 1.6 37.1 132.6 106.5 60.0 89.0 127.4
67.9 125.8 68.6 52.1 71.4 47.3 106.6 3.1 3.3
3.7 5.0 3.7 3.0 4.1 3.3 5.7 1.1 1.9
75.0 130.6 71.8 59.3 78.4 49.9 118.7 2.6 1.2
74.7 129.4 70.8 59.6 76.3 47.6 115.3 1.7 1.2
74.6 129.6 70.7 59.7 76.2 47.5 115.0 1.5 1.3
Means and standard deviations from Wada et al.31
Fig 4. Electromyographic recordings of masticatory muscles. Ta, Anterior temporalis muscle; Mm, masseter muscle; Tp, posterior temporalis muscle. DIAGNOSIS AND ETIOLOGY
A young woman, age 18 years 8 months, came to the outpatient clinic of Tohoku University Hospital in Japan. Her chief complaints were mandibular protrusion and facial asymmetry. The facial photographs showed a mandibular deviation toward the right and a concave profile (Fig 1). The mandibular dental midline was deviated 3.5 mm toward the right compared with the
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maxilla, and she had anterior and right posterior crossbites (Figs 1 and 2). The molar relationships were Class III on both sides. Overjet and overbite were –1.5 and 2 mm, respectively (Figs 1 and 2). A panoramic radiograph showed that all third molars were impacted (Fig 3). The cephalometric analysis showed a skeletal Class III jawbase relationship, an average mandibular plane angle, and normal inclinations of the maxillary and mandibular
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Fig 5. Occlusal force and occlusal contact area recordings (1 represents the center of the occlusal force): A, pretreatment; B, posttreatment; C, postretention. Rt, Right side; Lt, left side.
Table II. Occlusal force and occlusal contact area Pretreatment
Occlusal force (N) % Occlusal contact area (mm2) %
Total 735.2 100 17.1 100
Right 475.7 64.7 10.6 62.0
Posttreatment Left 259.5 35.3 6.5 38.0
Total 518.2 100 11.3 100
Right 263.4 50.8 5.9 51.9
Postretention Left 254.8 49.2 5.4 48.1
Total 837.3 100 23.4 100
Right 422.0 50.4 12.4 52.9
Left 415.3 49.6 11.0 47.1
Fig 6. Sagittal view of condylar movement during 6 degrees of freedom jaw movement recording.
anterior teeth (Fig 3, Table I). The posteroanterior cephalogram showed a mandibular deviation toward the right of 4 mm. Electromyographic monitoring showed that activities of the masseter and anterior and posterior temporalis muscles were lower during unilateral chewing on the
left side than on the right side (Fig 4). During tapping, the masseter muscle was mainly activated on the right side; in contrast, the posterior temporalis muscle was mainly activated on the left side. An occlusal-force recording system showed higher values of occlusal force and occlusal contact area on the right side than on the
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Table III. Condylar path length during jaw movements Condylar path length (mm) Maximum open-close Right Left Laterotrusion Right Left Protrusion Right Left
Pretreatment
Posttreatment
Postretention
12.8 11.5
16.4 11.2
17.2 15.6
11.2 6.9
8.5 9.0
9.8 9.7
7.2 5.9
10.6 12.1
11.0 11.8
Fig 7. Magnetic resonance images: A-D, I-L, and Q-T, sagittal planes; E-H, M-P, and U-X, coronal planes. Arrows show disc positions: a, Anterior side; p, posterior side; m, mesial side; l, lateral side.
left (Fig 5, A; Table II). A 6 degrees of freedom jaw movement recording system showed that condylar path length was shorter on the left side than on the right during lateral and protrusive jaw movements (Fig 6, Table III). Manipulation of the TMJ elicited clicking sounds on the left side. The sagittal magnetic resonance images showed anterior articular disc displacement with reduction on the right TMJ (Fig 7, A and C). In contrast, a normal disc position was shown on the left side (Fig 7, B and D). The coronal magnetic resonance images did not show a transverse displacement of the disc on the right side (Fig 7, E and G). On the left side, lateral displacement of the anterior band of the disc was shown in the closed-mouth position, but not in the openmouth position (Fig 7, F and H).
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TREATMENT OBJECTIVES
The patient was diagnosed as having a skeletal Class III jaw-base relationship, mandibular asymmetry, unilateral crossbite, asymmetric stomatognathic functions, and TMD. The treatment objectives were to correct the skeletal deformity, obtain an ideal occlusion, and improve the asymmetric stomatognathic functions by a combination of surgery and orthodontic therapy. We planned to perform presurgical orthodontic treatment focused on maintaining normal inclinations of the maxillary and mandibular incisors to obtain an ideal incisor relationship after surgery. A bilateral sagittal split ramus osteotomy was planned to correct the mandibular asymmetry
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Fig 8. Posttreatment facial and intraoral photographs.
and the protrusion after the improvement of the asymmetric stomatognathic function. The impacted mandibular right and left third molars were to be extracted before surgery so as not to interfere with the surgical procedures.
expected that asymmetric stomatognathic functions could be improved in patients with mandibular asymmetry by orthognathic surgery.17,18 Therefore, we decided to perform a combination of surgery and orthodontic therapy to improve both dentofacial morphology and stomatognathic functions.
TREATMENT ALTERNATIVES
Because it is possible to achieve a good treatment outcome using miniscrew anchorage in patients with a skeletal discrepancy, orthodontic camouflage with miniscrew anchorage could be a treatment alternative to correct the anterior and unilateral crossbites in our patient.16 However, it could not sufficiently correct the mandibular protrusion and the facial asymmetry, which were the patient’s chief complaints. Furthermore, it was
TREATMENT PROGRESS
After checking the oral hygiene status and giving toothbrushing instructions, we placed 0.018 3 0.025-in preadjusted edgewise appliances on the maxillary and mandibular dental arches, and leveling and alignment were started with 0.016-in and 0.014-in nickel-titanium archwires for the maxilla and mandible, respectively. Subsequently, tooth alignment proceeded by changing the
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Fig 9. Posttreatment dental casts.
Fig 10. Posttreatment cephalometric and panoramic radiographs.
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Fig 11. Superimposed pretreatment (solid line) and posttreatment (dotted line) cephalometric tracings: A, on the sella-nasion plane at sella; B, on the palatal plane at ANS; C, on the mandibular plane at menton.
archwires sequentially, and 0.016 3 0.022-in stainless steel archwires were used to adjust the tooth positions just before surgery. Both mandibular third molars were extracted 5 months before surgery, and the extraction sockets were cured by bone formation at the time of surgery. After presurgical orthodontic treatment for 1 year 4 months, a sagittal split ramus osteotomy was performed. The mandible was set back 2 mm on the right side and 5.5 mm on the left side. Postsurgical orthodontic treatment was performed for 7 months. The occlusion was detailed using 0.017 3 0.025-in beta-titanium archwires, and then the edgewise appliances were removed. The duration of active treatment was 2 years 1 month. Retention was started with Begg-type retainers, and the patient was followed for 2 years. TREATMENT RESULTS
As a result of the setback and the transverse rotation of the mandible by the sagittal split ramus osteotomy, the mandibular protrusion and the asymmetry were corrected, and facial esthetics were improved (Fig 8). The anterior and right posterior crossbites were corrected, and the mandibular midline was coincident with the maxillary midline (Figs 8 and 9). Class I canine and molar relationships were obtained. The posttreatment panoramic radiograph showed no remarkable apical root
resorption or alveolar bone loss (Fig 10). The posttreatment cephalometric analysis showed that a skeletal Class I jaw relationship had been achieved (Figs 10 and 11, Table I). Clear changes of the maxillary and mandibular incisor inclinations were not shown, indicating that the normal incisor inclinations were maintained (Figs 10 and 11, Table I). A posteroanterior cephalogram showed that the mandibular midline coincided with the facial midline (Fig 10). A posttreatment electromyographic recording showed no remarkable differences of the activity of the masseter and the anterior and posterior temporalis muscles during unilateral chewing on the left and right sides (Fig 4). During tapping, activities of these masticatory muscles were balanced on the 2 sides (Fig 4). However, activity of the masticatory muscles decreased during clenching (Fig 4). Occlusal force and occlusal contact area showed almost the same values on the left and right sides, although each value decreased compared with the values before treatment (Fig 5, B; Table II). The 6 degrees of freedom jaw movement recording system showed an increase of the right condylar path length during maximum mouth opening and closing (Fig 6, Table III). The asymmetric condylar path lengths during lateral and protrusive jaw movements were improved (Fig 6, Table III). In addition, the condylar path lengths on
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Fig 12. Postretention facial and intraoral photographs.
both sides increased during protrusive jaw movements (Fig 6, Table III). The clicking sounds still remained, and the sagittal and coronal magnetic resonance images showed no clear changes of articular disc positions (Fig 7, I-P). After 2 years of retention, an acceptable facial profile and occlusion were maintained (Figs 12-15, Table I). The symmetric masticatory muscle activities were also maintained (Fig 4). Moreover, they were increased during tapping and clenching compared with those at posttreatment. The occlusal force and occlusal contact area increased during the retention phase, and they showed higher values than before treatment (Fig 5, C; Table II). The left condylar path length during maximum mouth opening and closing increased; consequently, the difference of condylar path length between the right and
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left sides shown just after active treatment was corrected (Fig 6, Table III). The symmetric condylar path lengths during lateral and protrusive jaw movements were maintained. Although the disc displacement and the clicking sounds still remained in the TMJ, they have not worsened (Fig 7, Q-X). DISCUSSION
Patients with mandibular asymmetry and unilateral crossbite have asymmetric activity of masticatory muscles.3,19 Asymmetry of muscle size and orientation, and a difference of myosin heavy chain composition between the right and left sides might be associated with the asymmetric activity of the masticatory muscles in these patients.20,21 Sforza et al17 reported that orthognathic surgery for a mandibular
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Fig 13. Postretention dental casts.
Fig 14. Postretention cephalometric and panoramic radiographs.
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Fig 15. Superimposed posttreatment (solid line) and postretention (dotted line) cephalometric tracings: A, on the sella-nasion plane at sella; B, on the palatal plane at ANS; C, on the mandibular plane at menton.
prognathism patient with mandibular asymmetry resulted in improvement of the asymmetric activity of the masticatory muscles. In our patient, activities of the masseter and anterior and posterior temporalis muscles were lower during unilateral chewing on the left side than on the right side before treatment. Furthermore, the masseter muscle and the posterior temporalis muscle were mainly activated on the right and the left sides during tapping, respectively. These results indicated asymmetric activity of the masticatory muscles in this patient. On the other hand, the posttreatment electromyographic recording showed symmetric activities of the masticatory muscles during unilateral chewing and tapping, and these results suggest that this patient obtained balanced masticatory muscle activity by surgical orthodontics. It is known that occlusal force and occlusal contact area are greater on the deviated side than on the nondeviated side in patients with mandibular asymmetry.7 However, the effects of surgical orthodontics on the asymmetry of occlusal force and occlusal contact area are unclear. In this patient, occlusal force and occlusal contact area were greater on the deviated side than on the nondeviated side before treatment. On the other hand, they were balanced between the 2 sides after postsurgical orthodontic therapy. These results suggest the possibility of correcting the asymmetry of occlusal force and
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occlusal contact area by surgical orthodontics in patients with mandibular asymmetry. The effects of orthognathic surgery on masticatory muscle activity and occlusal force have been individually reported.22,23 However, there have been no reports regarding simultaneous longitudinal assessments of masticatory muscle activity, occlusal force, and occlusal contact area in a surgical orthodontic patient. In our patient, asymmetric masticatory muscle activity, occlusal force, and occlusal contact area were corrected after active treatment, and the obtained symmetric stomatognathic functions were maintained during the retention phase. Moreover, although the activity of the masticatory muscles and the values of occlusal force and occlusal contact area decreased after active treatment, they increased during retention and showed higher activity and values than before treatment. These results indicate the long-term stability of balanced stomatognathic function obtained by orthognathic surgery in a patient with mandibular asymmetry. Furthermore, it is suggested that stomatognathic function decreases just after active treatment, but it recovers and subsequently exceeds the pretreatment values during the retention phase, possibly in correlation with masticatory muscle activity, occlusal force, and occlusal contact area in surgical orthodontic patients.
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In patients with mandibular deviation, condylar path length on the deviated side was longer than on the nondeviated side during mouth opening and closing, and lateral and protrusive jaw movements.5,6 Not only skeletal discrepancy but also asymmetric condylar movement can be corrected by orthognathic surgery for patients with mandibular asymmetry.11,18 In this patient, condylar path length on the nondeviated side was shorter than on the deviated side during lateral and protrusive jaw movements before treatment. The asymmetric condylar path length was corrected after active treatment, mainly because of an increase of condylar path length on the nondeviated side. These results are consistent with previous reports.5,6,11,18 However, the relationships between condylar movement and masticatory muscle activity have been unclear. In this patient, improvements of asymmetric condylar movement and masticatory muscle activity were shown after active treatment. Because jaw movement is directly regulated by the contraction of the masticatory muscles, it is speculated that skeletal correction by orthognathic surgery resulted in improvement of asymmetric masticatory muscle activity, followed by improvement of asymmetric condylar movement.24 Moreover, little is known about the change of the condylar path length during the retention phase in patients who undergo orthognathic surgery. In this patient, condylar path length on both sides during maximum mouth opening and closing increased during the retention phase. The inferior head of the lateral pterygoid muscle regulates the anterior movement of the condyle during mouth opening.25 Because activities of the masseter muscle and the anterior and posterior temporalis muscles increased during the retention phase in this patient, it is possible that activity of the lateral pterygoid muscle also increased and contributed to the increase of the condylar path length. It has been reported that there is a close relationship between mandibular asymmetry and TMD.12,13,26 It is important to make a diagnosis of TMD before orthodontic treatment of patients with mandibular asymmetry. Disc displacement, which is a form of TMD, is often diagnosed by analysis of the anteroposterior disc position with sagittal magnetic resonance images. However, coronal magnetic resonance images are needed to diagnose transverse displacement and rotation of the disc.27 In this patient, the coronal magnetic resonance images showed lateral displacement of the anterior band of the disc on the nondeviated side in the closed-mouth position, but no displacement in the open-mouth position. These results suggest lateral disc displacement with reduction on the nondeviated side. A common cause of clicking in the
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TMJ is disc displacement with reduction.28 Therefore, the clicking sound on the nondeviated side in this patient might have been due to the reduction of the lateral disc displacement. In addition, anterior disc displacement is frequently seen on the deviated side in patients with mandibular asymmetry.12,29 Anterior disc displacement with reduction was observed on the deviated side in our patient. Because overload of the TMJ can be a cause of disc displacement, it is suggested that asymmetric occlusal force and masticatory muscle activity lead to overload of the TMJ on the deviated side and then cause anterior disc displacement.30 It has been reported that an intraoral ramus osteotomy can improve anterior disc displacement.10 However, little is known about the effect of orthognathic surgery on transverse disc displacement. Although there were no clear changes of the lateral disc displacement after the sagittal split ramus osteotomy in this patient, further study is needed to clarify the effect of orthognathic surgery on transverse disc position by evaluating coronal magnetic resonance images. CONCLUSIONS
Longitudinal simultaneous evaluation of stomatognathic function was performed as well as analysis of dentofacial morphology for a skeletal Class III patient with mandibular asymmetry. As a result of the evaluation, it was indicated for the first time that surgical orthodontics could comprehensively improve asymmetric stomatognathic functions including masticatory muscle activity, condylar movement, and occlusal force. In addition, with sagittal and coronal magnetic resonance images, we could evaluate the 3-dimensional position of the articular disc, and it was shown that although the articular disc displacements were not corrected, at least no worsening of these displacements occurred after surgery in this patient. This case report demonstrates the importance of analysis of stomatognathic function and the TMJ as well as dentofacial morphology to make a diagnosis and to evaluate the treatment outcome in a patient with a dentofacial skeletal deformity. REFERENCES 1. Kobayashi T, Honma K, Shingaki S, Nakajima T. Changes in masticatory function after orthognathic treatment in patients with mandibular prognathism. Br J Oral Maxillofac Surg 2001;39: 260-5. 2. Deguchi T, Garetto LP, Sato Y, Potter RH, Roberts WE. Statistical analysis of differential lissajous EMG from normal occlusion and Class III malocclusion. Angle Orthod 1995;65:151-60. 3. Dong Y, Wang XM, Wang MQ, Widmalm SE. Asymmetric muscle function in patients with developmental mandibular asymmetry. J Oral Rehabil 2008;35:27-36.
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4. Wang D, Fu H, Zeng R, Yang X. Changes of mandibular movement tracings after the correction of mandibular protrusion by bilateral sagittal split ramus osteotomy. J Oral Maxillofac Surg 2009;67: 2238-44. 5. Oguri Y, Yamada K, Fukui T, Hanada K, Kohno S. Mandibular movement and frontal craniofacial morphology in orthognathic surgery patients with mandibular deviation and protrusion. J Oral Rehabil 2003;30:392-400. 6. Ishizaki K, Suzuki K, Mito T, Tanaka EM, Sato S. Morphologic, functional, and occlusal characterization of mandibular lateral displacement malocclusion. Am J Orthod Dentofacial Orthop 2010;137:454.e1-9. 7. Goto TK, Yamada T, Yoshiura K. Occlusal pressure, occlusal contact area, force and the correlation with the morphology of the jaw-closing muscles in patients with skeletal mandibular asymmetry. J Oral Rehabil 2008;35:594-603. 8. Maeda A, Soejima K, Ogura M, Ohmure H, Sugihara K, Miyawaki S. Orthodontic treatment combined with mandibular distraction osteogenesis and changes in stomatognathic function. Angle Orthod 2008;78:1125-32. 9. Nakajima K, Yamaguchi T, Maki K. Surgical orthodontic treatment for a patient with advanced periodontal disease: evaluation with electromyography and 3-dimensional conebeam computed tomography. Am J Orthod Dentofacial Orthop 2009;136:450-9. 10. Miyatake E, Miyawaki S, Morishige Y, Nishiyama A, Sasaki A, Takano-Yamamoto T. Class III malocclusion with severe facial asymmetry, unilateral posterior crossbite, and temporomandibular disorders. Am J Orthod Dentofacial Orthop 2003;124: 435-45. 11. Hashimoto T, Fukunaga T, Kuroda S, Sakai Y, Yamashiro T, Takano-Yamamoto T. Mandibular deviation and canted maxillary occlusal plane treated with miniscrews and intraoral vertical ramus osteotomy: functional and morphologic changes. Am J Orthod Dentofacial Orthop 2009;136:868-77. 12. 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. 13. 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. 14. Goto TK, Nishida S, Nakayama E, Nakamura Y, Sakai S, Yabuuchi H, et al. Correlation of mandibular deviation with temporomandibular joint MR dimensions, MR disk position, and clinical symptoms. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2005;100:743-9. 15. Hu J, Wang D, Zou S. Effects of mandibular setback on the temporomandibular joint: a comparison of oblique and sagittal split ramus osteotomy. J Oral Maxillofac Surg 2000; 58:375-80.
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16. Sakai Y, Kuroda S, Murshid SA, Takano-Yamamoto T. Skeletal Class III severe openbite treatment using implant anchorage. Angle Orthod 2008;78:157-66. 17. Sforza C, Peretta R, Grandi G, Ferronato G, Ferrario VF. Soft tissue facial planes and masticatory muscle function in skeletal Class III patients before and after orthognathic surgery treatment. J Oral Maxillofac Surg 2008;66:691-8. 18. Hashimoto T, Kuroda S, Lihua E, Tanimoto Y, Miyawaki S, TakanoYamamoto T. Correlation between craniofacial and condylar path asymmetry. J Oral Maxillofac Surg 2008;66:2020-7. 19. Matsumoto R, Ioi H, Goto TK, Hara A, Nakata S, Nakasima A, et al. Relationship between the unilateral TMJ osteoarthritis/osteoarthrosis, mandibular asymmetry and the EMG activity of the masticatory muscles: a retrospective study. J Oral Rehabil 2010; 37:85-92. 20. Goto TK, Nishida S, Yahagi M, Langenbach GE, Nakamura Y, Tokumori K, et al. Size and orientation of masticatory muscles in patients with mandibular laterognathism. J Dent Res 2006;85: 552-6. 21. Raoul G, Rowlerson A, Sciote J, Codaccioni E, Stevens L, Maurage CA, et al. Masseter myosin heavy chain composition varies with mandibular asymmetry. J Craniofac Surg 2011;22:1093-8. 22. Trawitzki LV, Dantas RO, Mello-Filho FV, Marques W Jr. Masticatory muscle function three years after surgical correction of Class III dentofacial deformity. Int J Oral Maxillofac Surg 2010;39: 853-6. 23. Kim YG, Oh SH. Effect of mandibular setback surgery on occlusal force. J Oral Maxillofac Surg 1997;55:121-6. 24. Greenfield BE, Wyke BD. Electromyographic studies of some of the muscles of mastication. Br Dent J 1956;100:129-43. 25. Ash MM Jr. Wheeler’s dental anatomy, physiology and occlusion. Philadelphia: W. B. Saunders; 1993. 26. 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. 27. Arat FE, Arat ZM, Tompson B, Tanju S. Muscular and condylar response to rapid maxillary expansion. Part 3: magnetic resonance assessment of condyle-disc relationship. Am J Orthod Dentofacial Orthop 2008;133:830-6. 28. Isberg A. Temporomandibular joint dysfunction: a practitioner’s guide. Oxford: Isis Medical Media; 2001. 29. Link JJ, Nickerson JW Jr. Temporomandibular joint internal derangements in an orthognathic surgery population. Int J Adult Orthod Orthognath Surg 1992;7:161-9. 30. Nitzan DW. The process of lubrication impairment and its involvement in temporomandibular joint disc displacement: a theoretical concept. J Oral Maxillofac Surg 2001;59:36-45. 31. Wada K, Matsushita K, Shimazaki S, Miwa Y, Hasuike Y, Susami R. An evaluation of a new case analysis of a lateral cphalometric roentgenogram. J Kanazawa Med Univ 1981;6: 60-70.
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