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Changes in border movement of the mandible in skeletal Class III before and after orthognathic surgery
Int. J. Oral Maxillofac. Surg. 2014; 43: 213–216 http://dx.doi.org/10.1016/j.ijom.2013.07.740, available online at http://www.sciencedirect.com
Clinical Paper Orthognathic Surgery
Changes in border movement of the mandible in skeletal Class III before and after orthognathic surgery
K. Ueki, K. Marukawa, A. Moroi, M. Sotobori, Y. Ishihara, R. Iguchi, A. Kosaka, Y. Nakano, M. Higuchi, R. Nakazawa Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
K. Ueki, K. Marukawa, A. Moroi, M. Sotobori, Y. Ishihara, R. Iguchi, A. Kosaka, Y. Nakano, M. Higuchi, R. Nakazawa: Changes in border movement of the mandible in skeletal Class III before and after orthognathic surgery. Int. J. Oral Maxillofac. Surg. 2014; 43: 213–216. # 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The purpose of this study was to examine the changes in border movement of the mandible before and after mandibular ramus osteotomy in patients with prognathism. The subjects were 73 patients with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO) with and without Le Fort I osteotomy. Border movement of the mandible was recorded with a mandibular movement measure system (K7) preoperatively and at 6 months postoperatively. Of the 73 patients, 21 had measurements taken at 1.5 years postoperative. Data were compared between the pre- and postoperative states, and the differences analyzed statistically. There was no significant difference between SSRO alone and SSRO with Le Fort I osteotomy in the time-course change. The values at 6 months postoperative were significantly lower than the preoperative values for maximum vertical opening (P = 0.0066), maximum antero-posterior movement from the centric occlusion (P = 0.0425), and centric occlusion to maximum opening (P = 0.0300). However, there were no significant differences between the preoperative and 1.5 years postoperative measurements. This study suggests that a postoperative temporary reduction in the border movement of the mandible could recover by 1.5 years postoperative, and the additional procedure of a Le Fort I osteotomy does not affect the recovery of mandibular motion after SSRO.
Orthognathic surgery can induce not only morphological but also functional improvements. However, surgical invasion can affect the recovery of mandibular functions. Several investigators have assessed the immediate to medium term functional results, as all groups of skeletal 0901-5027/020213 + 04 $36.00/0
malocclusion tend to have some degree of hypomobility of the temporomandibular joint (TMJ) postoperatively.1–9 Surgical orthodontic correction of skeletal Class III physiology has been reported to have favourable effects on the function of the mandible, such as
Key words: border movement of the mandible; orthognathic surgery; sagittal split ramus osteotomy; Le Fort I osteotomy. Accepted for publication 16 July 2013 Available online 14 August 2013
increased ranges of maximum motion in the anterior, posterior, and lateral excursions.10 It was shown in previous questionnaire studies that, with the recovery of normal occlusion, there was an improvement in chewing efficiency in more than 75% of patients who had undergone
# 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
214
Ueki et al.
surgical–orthodontic correction of a skeletal Class III malocclusion.11,12 Yazdani et al.13 concluded that sagittal split ramus osteotomy (SSRO) resulted in the greatest effect, and extraoral vertical ramus osteotomy (EVRO) in the least effect, on limitation of movement after mandibular setback surgery, although electric devices such as the kinesiograph were not used in that study. Studies using the kinesiograph for mandibular motion after mandibular setback surgery with Le Fort I osteotomy are few, although there are some studies on mandibular advancement surgery and mandibular setback surgery alone. The purpose of this study was to examine the time-course changes in mandibular motion before and after SSRO with and without Le Fort I osteotomy for patients with prognathism, using a kinesiograph. Patients and methods Patients
The subjects consisted of 16 men and 57 women (average age 30.6 11.7 years) with mandibular prognathism without severe TMJ dysfunction. The subjects had no history of temporomandibular disorder such as locking. The patients with slight muscular dysfunction or sound in the TMJ were included, however subjects with maximum vertical mouth opening of under 30 mm were excluded. Forty-one patients underwent SSRO alone and 32 underwent SSRO with Le Fort I osteotomy. Two unsintered hydroxyapatite and polyL-lactic acid (uHA/PLLA) miniplates
(28 mm 4.5 mm 1.5 mm with four screws (2 mm 8 mm); Super-FixorbMX, Takiron Co., Osaka, Japan) were used for bilateral internal fixation of the mandible (the u-HA/PLLA group). Two uHA/PLLA L-type miniplates (10 mm 22 mm 1.4 mm with four screws (2 mm 8 mm); Super-Fixorb-MX, Takiron Co.) and straight uHA/PLLA plates two (28 mm 4.5 mm 1.4 mm with four screws (2 mm 8 mm); Super-FixorbMX, Takiron Co.) were used to fix the maxilla. None of the patients underwent maxillomandibular fixation (MMF) after surgery. However, maxilla–mandibular traction with an elastic was performed until the occlusion was stable. No patient performed postoperative mandibular exercises or training to promote recovery of mandibular motion. Border movement of the mandible was recorded with a mandibular movement measurement system (K7; Myotronics Inc., Kent, WA, USA) preoperatively and at 6 months postoperatively. Multiple sensors in a lightweight array tracked the motion of a magnet attached to the midpoint of the lower incisors (Fig. 1). Of the 73 patients, 21 had measurements taken until 1.5 years postoperative. Preoperative and postoperative measurements of maximum vertical opening, maximum antero-posterior movement from centric occlusion, maximum lateral deviation on the left and right, and centric occlusion to maximum opening were compared and the differences analyzed statistically.
Statistical analysis
Data were analyzed using Dr. SPSS II (SPSS Japan Inc., Tokyo, Japan). The total time-course changes from preoperative to 6 months and 1.5 years postoperative were examined by repeated measures analysis of variance (ANOVA). Comparisons between each time period were performed by paired t-test. Differences were considered significant at P < 0.05. Results
There was no significant difference between SSRO alone and SSRO with Le Fort I osteotomy in the time-course change by repeated measures ANOVA. With regard to the results of the 73 subjects observed preoperatively and at 6 months postoperatively, the values at 6 months postoperative were significantly lower than the preoperative values for maximum vertical opening (P < 0.0001), maximum antero-posterior movement from centric occlusion (P < 0.0001), and centric occlusion to maximum opening (P < 0.0001). When the paired comparisons were performed statistically in the 21 patients who had measurements taken at 1.5 years, similar results were obtained (Fig. 2 and Table 1). The values at 6 months postoperative were significantly lower than the preoperative values for maximum vertical opening (P = 0.0066), maximum anteroposterior movement from centric occlusion (P = 0.0425), and centric occlusion to maximum opening (P = 0.0300). However, there were no significant differences between the preoperative and 1.5 years postoperative measurements. Discussion
Fig. 1. (A) The K7 system. (B) Multiple sensors, in an extremely lightweight (four ounces) spectacle-like array, track the motion of a tiny magnet attached to the lower incisal gingiva with adhesive material. (C) Tracking of the border movement of the mandible.
SSRO surgical methods have been used for many years to correct mandibular prognathism. SSRO with rigid fixation has several advantages associated with it, such as a larger bony interface between the segments, easier fixation, and earlier healing. Therefore, SSRO can provide immediate postoperative jaw mobilization without MMF. Furthermore, Le Fort I osteotomy is also used very frequently with SSRO for orthognathic surgery.14 As functional changes following orthognathic surgery are important, many studies have documented masticatory functions such as masticatory efficiency,14,15 muscle activity,16 bite force, and occlusal contacts.17–20 Several studies have reported that mandibular advancement surgery limits mandibular mobility
Changes in border movement of the mandible (mm) 70 60
50 40
Pre-operaon 6 months
30
1.5 years
20 10 0
MVO
CO to MAP
MLDL
MLDR
CO to MO
Fig. 2. Results of border movement of the mandible in the patients followed up for 1.5 years. MVO, maximum vertical opening; CO to MAP, maximum antero-posterior movement from centric occlusion; MLDL, maximum lateral deviation left; MLDR, maximum lateral deviation right; CO to MO, centric occlusion to maximum opening. Error bars indicate the standard deviation.
to a greater extent than some other orthognathic surgical procedures. Other studies have indicated that this reduction in mobility is temporary, resolving within 6 months to 1 year. Aragon et al.21 reported that protrusive movement and lateral excursion of the mandible did not recover to the preoperative levels after a sagittal split osteotomy was performed for advancement of the mandible. Boyd et al.22 also reported a significant reduction in protrusive movement in patients who had undergone sagittal split osteotomies for correction of mandibular retrusion. On the other hand, Nagamine et al.10 reported that the mean maximum anterior and posterior excursions of the mandible, as well as the lateral excursion, increased significantly after corrective surgery. Youssef et al.23 reported that mandibular excursions and cycle duration during mastication changed significantly with surgery. Boyd et al.22 reported that significant differences in the recovery patterns of mandibular mobility exist between SSRO and intraoral vertical ramus osteotomy (IVRO) procedures; this was demonstrated by measuring the maximal mandibular opening and the lateral
and protrusive excursions. In the study of Yazdani et al.13 on Class III patients, reduced mandibular movement range was one of the complications of SSRO, IVRO, and EVRO. In this study, reduced mandibular motion was recognized in the maximum vertical opening, maximum antero-posterior movement from centric occlusion, and centric occlusion to maximum opening after 6 months. However, values had recovered by 1.5 years postoperative, although the mean values did not reach the preoperative values. This result may have been affected by a decrease in mandibular length by setback surgery. On the other hand, maximum lateral deviation on the left and right were also reduced after 6 months. However, the values after 1.5 years tended to be larger than the preoperative values. This change might be related to the change in the chewing path after surgery. In short, this result suggests that the chewing movement changed from a linear pattern with a long opening distance to a lateral grinding movement. With regard to chewing pattern, Arai and Ishikawa24 suggested that the skeletal Class III physiology typically demon-
Table 1. Results of border movement of the mandible through 1.5 years of follow-up (n = 21 patients). Preoperative, mm
MVO CO to MAP MLDL MLDR CO to MO
6 months, mm
1.5 years, mm
Mean
SD
Mean
SD
Mean
SD
38.8 24.7 6.3 7.9 48.1
10.0 9.0 4.3 4.4 12.9
32.8 19.6 5.9 6.4 41.7
10.7 9.5 3.5 3.5 15.1
36.1 25.1 6.9 8.6 44.1
10.1 7.8 2.8 3.5 12.6
SD, standard deviation; MVO, maximum vertical opening; CO to MAP, maximum anteroposterior movement from centric occlusion; MLDL, maximum lateral deviation left; MLDR, maximum lateral deviation right; CO to MO, centric occlusion to maximum opening.
215
strates an unstable linear pattern with a long opening distance. Proschel et al.25 concluded that patients with prognathism most frequently exhibit chopping patterns characterized by nearly vertical closing strokes, whereas mastication in patients without prognathism is dominated by lateral grinding movements. Proschel et al.25 found that the characteristic chewing mode of a person with mandibular prognathism did not interfere with the occlusal profile, and hence did not react to alterations. In our previous study,26 no significant differences were found in the distributions of chewing patterns in both the symmetry and asymmetry groups before and after treatment. These results suggest that surgical orthodontic treatment does not significantly change the chewing pattern in patients with prognathism regardless of symmetry. The habitual chewing movement may be related to limited mandibular movement, although these movements serve different functions so they are difficult to compare functionally. In this study, there was no significant difference in time-course changes in mandibular motion between SSRO alone and SSRO with Le Fort I osteotomy. Previous studies on functional examination have shown a similar tendency. For the change in maximum mouth opening (MMO), the differences among surgical procedures (SSRO with and without Le Fort I osteotomy, IVRO with and without Le Fort I osteotomy) and the relationship between MMO and the MMF period were examined statistically. Results suggested that there were no significant differences between single-jaw surgery and doublejaw surgery in terms of postoperative time-dependent changes in the recovery of MMO. However, the MMF period was associated with the recovery of MMO.4 For the changes in occlusal force and contact, the difference among surgical procedures (SSRO with and without Le Fort I osteotomy, IVRO with and without Le Fort I osteotomy) was examined statistically. Results suggested that the combination of IVRO or SSRO and Le Fort I osteotomy did not affect postoperative time-dependent changes.27 In conclusion, this study suggests that a postoperative temporary reduction in the border movement of the mandible could recover by 1.5 years postoperative, and the additional procedure of a Le Fort I osteotomy did not affect the recovery of mandibular motion after SSRO. Funding
None.
216
Ueki et al.
Competing interests
None declared. 9.
Ethical approval
Not required.
10.
Patient consent
Not required. 11.
References 1. Stacy GC. Recovery of oral opening following sagittal ramus osteotomy for mandibular prognathism. J Oral Maxillofac Surg 1987;45:487–92. 2. Athanasiou AE. Electrognathographic patterns of mandibular motion after bilateral vertical ramus setback osteotomy. Int J Adult Orthodon Orthognath Surg 1992;7: 23–9. 3. Yang XW, Long X, Yeweng SJ, Kao CT. Evaluation of mandibular setback after bilateral sagittal split osteotomy with Hunsuck modification and miniplate fixation. J Oral Maxillofac Surg 2007;65:2176–80. 4. Ueki K, Marukawa K, Hashiba Y, Nakagawa K, Degerliyurt K, Yamamoto E. Assessment of the relationship between the recovery of maximum mandibular opening and the maxillomandibular fixation period after orthognathic surgery. J Oral Maxillofac Surg 2008;66:486–91. 5. Throckmorton GS, Ellis III E, Sinn DO. Functional characteristics of retrognathic patients before and after mandibular advancement surgery. J Oral Maxillofac Surg 1995;53:898–909. 6. Zarrinkelk HM, Throckmorton GS, Ellis III E, Sinn DP. Functional and morphological alterations secondary to superior repositioning of the maxilla. J Oral Maxillofac Surg 1995;53:1258–67. 7. Song HC, Throckmorton GS, Ellis III E, Sinn DP. Functional and morphological alterations after anterior and/or inferior repositioning of the maxilla. J Oral Maxillofac Surg 1997;55:41–50. 8. Zarrinkelk HM, Throckmorton GS, Ellis III E, Sinn DP. Functional and morphological
12.
13.
14.
15.
16.
17.
18.
19.
changes after combined maxillary intrusion and mandibular advancement surgery. J Oral Maxillofac Surg 1996;54:828–37. Throckmorton GS. Functional deficits in orthognathic surgery patients. Semin Orthod 2006;12:127–37. Nagamine T, Kobayashi T, Nakajima T, Hanada K. The effects of surgical-orthodontic correction of skeletal Class III malocclusion on mandibular movement. J Oral Maxillofac Surg 1993;51:385–9. Tomizawa M, Nakajima T, Ueda K, Azumi T, Hanada K. Evaluation by patients of surgical orthodontic correction of skeletal Class III malocclusion: survey of 41 patients. J Oral Surg 1981;39:590–6. Nagamine T, Kobayashi T, Hanada K, Nakajima T. Satisfaction of patients following surgical-orthodontic correction of skeletal Class III malocclusions. J Oral Maxillofac Surg 1986;44:944–8. Yazdani J, Ebrahimi H, Talesh KT, Khashabi E, Pourshahidi S, Tadbir AA. Comparing the effect of 3 orthognathic surgical methods on the mandibular range of movement. J Craniofac Surg 2010;21:703–5. Shiratsuchi Y, Kouno K, Tashiro H. Evaluation of masticatory function following orthognathic surgical correction of mandibular prognathism. J Craniomaxillofac Surg 1991;19:299–303. Kobayashi T, Honma K, Nakajima T, Hanada K. Masticatory function in patients with mandibular prognathism before and after orthognathic surgery. J Oral Maxillofac Surg 1993;51:997–1001. Raustia AM, Oikarinen KS. Change in electric activity of masseter and temporal muscles after mandibular sagittal split osteotomy. Int J Oral Maxillofac Surg 1994;23:180–4. Ellis E, Throckmorton GS, Sinn DP. Bite forces before and after surgical correction of mandibular prognathism. J Oral Maxillofac Surg 1996;54:176–81. Throckmorton GS, Buschang PH, Ellis E. Improvement of maximum occlusal forces after orthognathic surgery. J Oral Maxillofac Surg 1996;54:1080–6. Kim YG, Oh SH. Effect of mandibular setback surgery on occlusal force. J Oral Maxillofac Surg 1997;55:121–6.
20. Iwase M, Sugimori M, Kurachi Y, Nagumo M. Changes in bite force and occlusal contacts in patients treated for mandibular prognathism by orthognathic surgery. J Oral Maxillofac Surg 1998;56:850–5. 21. Aragon SB, Van Sickels JE, Dolwick MF, Flanary CM. The effects of orthognathic surgery on mandibular range of motion. J Oral Maxillofac Surg 1985;43:938–43. 22. Boyd SB, Karas ND, Sinn DP. Recovery of mandibular mobility following orthognathic surgery. J Oral Maxillofac Surg 1991;49: 924–31. 23. Youssef RE, Throckmorton GS, Ellis III E, Sinn DP. Comparison of habitual masticatory cycle and muscle activity before and after orthognathic surgery. J Oral Maxillofac Surg 1997;55:699–707. 24. Arai K, Ishikawa H. Frontal chewing path incisor point in skeletal Class III patients. J Jpn Orthod Soc 1994;53:154–68. 25. Proschel PA, Hummer H, Hofmann M, Spitzer W. Reaction of mastication to occlusal changes induced by correction of mandibular prognathism. J Prosthet Dent 1990;64:211–8. 26. Ueki K, Marukawa K, Shimada M, Nakagawa K, Yamamoto E, Niizawa S. Changes in the chewing path of patients in skeletal Class III with and without asymmetry before and after orthognathic surgery. J Oral Maxillofac Surg 2005;63:442–8. 27. Ueki K, Marukawa K, Shimada M, Nakagawa K, Yamamoto E. Changes in occlusal force after mandibular ramus osteotomy with and without Le Fort I osteotomy. Int J Oral Maxillofac Surg 2007;36:301–4.
Address: Koichiro Ueki Department of Oral and Maxillofacial Surgery Division of Medicine Interdisciplinary Graduate School of Medicine and Engineering University of Yamanashi 1110 Shimokato Chuo Yamanashi 409-3893 Japan Tel: +81 55 273 9673; Fax: +81 55 273 8210 E-mails: [email protected], [email protected]
Clinical Paper Orthognathic Surgery
Changes in border movement of the mandible in skeletal Class III before and after orthognathic surgery
K. Ueki, K. Marukawa, A. Moroi, M. Sotobori, Y. Ishihara, R. Iguchi, A. Kosaka, Y. Nakano, M. Higuchi, R. Nakazawa Department of Oral and Maxillofacial Surgery, Division of Medicine, Interdisciplinary Graduate School of Medicine and Engineering, University of Yamanashi, Yamanashi, Japan
K. Ueki, K. Marukawa, A. Moroi, M. Sotobori, Y. Ishihara, R. Iguchi, A. Kosaka, Y. Nakano, M. Higuchi, R. Nakazawa: Changes in border movement of the mandible in skeletal Class III before and after orthognathic surgery. Int. J. Oral Maxillofac. Surg. 2014; 43: 213–216. # 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved. Abstract. The purpose of this study was to examine the changes in border movement of the mandible before and after mandibular ramus osteotomy in patients with prognathism. The subjects were 73 patients with mandibular prognathism who underwent sagittal split ramus osteotomy (SSRO) with and without Le Fort I osteotomy. Border movement of the mandible was recorded with a mandibular movement measure system (K7) preoperatively and at 6 months postoperatively. Of the 73 patients, 21 had measurements taken at 1.5 years postoperative. Data were compared between the pre- and postoperative states, and the differences analyzed statistically. There was no significant difference between SSRO alone and SSRO with Le Fort I osteotomy in the time-course change. The values at 6 months postoperative were significantly lower than the preoperative values for maximum vertical opening (P = 0.0066), maximum antero-posterior movement from the centric occlusion (P = 0.0425), and centric occlusion to maximum opening (P = 0.0300). However, there were no significant differences between the preoperative and 1.5 years postoperative measurements. This study suggests that a postoperative temporary reduction in the border movement of the mandible could recover by 1.5 years postoperative, and the additional procedure of a Le Fort I osteotomy does not affect the recovery of mandibular motion after SSRO.
Orthognathic surgery can induce not only morphological but also functional improvements. However, surgical invasion can affect the recovery of mandibular functions. Several investigators have assessed the immediate to medium term functional results, as all groups of skeletal 0901-5027/020213 + 04 $36.00/0
malocclusion tend to have some degree of hypomobility of the temporomandibular joint (TMJ) postoperatively.1–9 Surgical orthodontic correction of skeletal Class III physiology has been reported to have favourable effects on the function of the mandible, such as
Key words: border movement of the mandible; orthognathic surgery; sagittal split ramus osteotomy; Le Fort I osteotomy. Accepted for publication 16 July 2013 Available online 14 August 2013
increased ranges of maximum motion in the anterior, posterior, and lateral excursions.10 It was shown in previous questionnaire studies that, with the recovery of normal occlusion, there was an improvement in chewing efficiency in more than 75% of patients who had undergone
# 2013 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
214
Ueki et al.
surgical–orthodontic correction of a skeletal Class III malocclusion.11,12 Yazdani et al.13 concluded that sagittal split ramus osteotomy (SSRO) resulted in the greatest effect, and extraoral vertical ramus osteotomy (EVRO) in the least effect, on limitation of movement after mandibular setback surgery, although electric devices such as the kinesiograph were not used in that study. Studies using the kinesiograph for mandibular motion after mandibular setback surgery with Le Fort I osteotomy are few, although there are some studies on mandibular advancement surgery and mandibular setback surgery alone. The purpose of this study was to examine the time-course changes in mandibular motion before and after SSRO with and without Le Fort I osteotomy for patients with prognathism, using a kinesiograph. Patients and methods Patients
The subjects consisted of 16 men and 57 women (average age 30.6 11.7 years) with mandibular prognathism without severe TMJ dysfunction. The subjects had no history of temporomandibular disorder such as locking. The patients with slight muscular dysfunction or sound in the TMJ were included, however subjects with maximum vertical mouth opening of under 30 mm were excluded. Forty-one patients underwent SSRO alone and 32 underwent SSRO with Le Fort I osteotomy. Two unsintered hydroxyapatite and polyL-lactic acid (uHA/PLLA) miniplates
(28 mm 4.5 mm 1.5 mm with four screws (2 mm 8 mm); Super-FixorbMX, Takiron Co., Osaka, Japan) were used for bilateral internal fixation of the mandible (the u-HA/PLLA group). Two uHA/PLLA L-type miniplates (10 mm 22 mm 1.4 mm with four screws (2 mm 8 mm); Super-Fixorb-MX, Takiron Co.) and straight uHA/PLLA plates two (28 mm 4.5 mm 1.4 mm with four screws (2 mm 8 mm); Super-FixorbMX, Takiron Co.) were used to fix the maxilla. None of the patients underwent maxillomandibular fixation (MMF) after surgery. However, maxilla–mandibular traction with an elastic was performed until the occlusion was stable. No patient performed postoperative mandibular exercises or training to promote recovery of mandibular motion. Border movement of the mandible was recorded with a mandibular movement measurement system (K7; Myotronics Inc., Kent, WA, USA) preoperatively and at 6 months postoperatively. Multiple sensors in a lightweight array tracked the motion of a magnet attached to the midpoint of the lower incisors (Fig. 1). Of the 73 patients, 21 had measurements taken until 1.5 years postoperative. Preoperative and postoperative measurements of maximum vertical opening, maximum antero-posterior movement from centric occlusion, maximum lateral deviation on the left and right, and centric occlusion to maximum opening were compared and the differences analyzed statistically.
Statistical analysis
Data were analyzed using Dr. SPSS II (SPSS Japan Inc., Tokyo, Japan). The total time-course changes from preoperative to 6 months and 1.5 years postoperative were examined by repeated measures analysis of variance (ANOVA). Comparisons between each time period were performed by paired t-test. Differences were considered significant at P < 0.05. Results
There was no significant difference between SSRO alone and SSRO with Le Fort I osteotomy in the time-course change by repeated measures ANOVA. With regard to the results of the 73 subjects observed preoperatively and at 6 months postoperatively, the values at 6 months postoperative were significantly lower than the preoperative values for maximum vertical opening (P < 0.0001), maximum antero-posterior movement from centric occlusion (P < 0.0001), and centric occlusion to maximum opening (P < 0.0001). When the paired comparisons were performed statistically in the 21 patients who had measurements taken at 1.5 years, similar results were obtained (Fig. 2 and Table 1). The values at 6 months postoperative were significantly lower than the preoperative values for maximum vertical opening (P = 0.0066), maximum anteroposterior movement from centric occlusion (P = 0.0425), and centric occlusion to maximum opening (P = 0.0300). However, there were no significant differences between the preoperative and 1.5 years postoperative measurements. Discussion
Fig. 1. (A) The K7 system. (B) Multiple sensors, in an extremely lightweight (four ounces) spectacle-like array, track the motion of a tiny magnet attached to the lower incisal gingiva with adhesive material. (C) Tracking of the border movement of the mandible.
SSRO surgical methods have been used for many years to correct mandibular prognathism. SSRO with rigid fixation has several advantages associated with it, such as a larger bony interface between the segments, easier fixation, and earlier healing. Therefore, SSRO can provide immediate postoperative jaw mobilization without MMF. Furthermore, Le Fort I osteotomy is also used very frequently with SSRO for orthognathic surgery.14 As functional changes following orthognathic surgery are important, many studies have documented masticatory functions such as masticatory efficiency,14,15 muscle activity,16 bite force, and occlusal contacts.17–20 Several studies have reported that mandibular advancement surgery limits mandibular mobility
Changes in border movement of the mandible (mm) 70 60
50 40
Pre-operaon 6 months
30
1.5 years
20 10 0
MVO
CO to MAP
MLDL
MLDR
CO to MO
Fig. 2. Results of border movement of the mandible in the patients followed up for 1.5 years. MVO, maximum vertical opening; CO to MAP, maximum antero-posterior movement from centric occlusion; MLDL, maximum lateral deviation left; MLDR, maximum lateral deviation right; CO to MO, centric occlusion to maximum opening. Error bars indicate the standard deviation.
to a greater extent than some other orthognathic surgical procedures. Other studies have indicated that this reduction in mobility is temporary, resolving within 6 months to 1 year. Aragon et al.21 reported that protrusive movement and lateral excursion of the mandible did not recover to the preoperative levels after a sagittal split osteotomy was performed for advancement of the mandible. Boyd et al.22 also reported a significant reduction in protrusive movement in patients who had undergone sagittal split osteotomies for correction of mandibular retrusion. On the other hand, Nagamine et al.10 reported that the mean maximum anterior and posterior excursions of the mandible, as well as the lateral excursion, increased significantly after corrective surgery. Youssef et al.23 reported that mandibular excursions and cycle duration during mastication changed significantly with surgery. Boyd et al.22 reported that significant differences in the recovery patterns of mandibular mobility exist between SSRO and intraoral vertical ramus osteotomy (IVRO) procedures; this was demonstrated by measuring the maximal mandibular opening and the lateral
and protrusive excursions. In the study of Yazdani et al.13 on Class III patients, reduced mandibular movement range was one of the complications of SSRO, IVRO, and EVRO. In this study, reduced mandibular motion was recognized in the maximum vertical opening, maximum antero-posterior movement from centric occlusion, and centric occlusion to maximum opening after 6 months. However, values had recovered by 1.5 years postoperative, although the mean values did not reach the preoperative values. This result may have been affected by a decrease in mandibular length by setback surgery. On the other hand, maximum lateral deviation on the left and right were also reduced after 6 months. However, the values after 1.5 years tended to be larger than the preoperative values. This change might be related to the change in the chewing path after surgery. In short, this result suggests that the chewing movement changed from a linear pattern with a long opening distance to a lateral grinding movement. With regard to chewing pattern, Arai and Ishikawa24 suggested that the skeletal Class III physiology typically demon-
Table 1. Results of border movement of the mandible through 1.5 years of follow-up (n = 21 patients). Preoperative, mm
MVO CO to MAP MLDL MLDR CO to MO
6 months, mm
1.5 years, mm
Mean
SD
Mean
SD
Mean
SD
38.8 24.7 6.3 7.9 48.1
10.0 9.0 4.3 4.4 12.9
32.8 19.6 5.9 6.4 41.7
10.7 9.5 3.5 3.5 15.1
36.1 25.1 6.9 8.6 44.1
10.1 7.8 2.8 3.5 12.6
SD, standard deviation; MVO, maximum vertical opening; CO to MAP, maximum anteroposterior movement from centric occlusion; MLDL, maximum lateral deviation left; MLDR, maximum lateral deviation right; CO to MO, centric occlusion to maximum opening.
215
strates an unstable linear pattern with a long opening distance. Proschel et al.25 concluded that patients with prognathism most frequently exhibit chopping patterns characterized by nearly vertical closing strokes, whereas mastication in patients without prognathism is dominated by lateral grinding movements. Proschel et al.25 found that the characteristic chewing mode of a person with mandibular prognathism did not interfere with the occlusal profile, and hence did not react to alterations. In our previous study,26 no significant differences were found in the distributions of chewing patterns in both the symmetry and asymmetry groups before and after treatment. These results suggest that surgical orthodontic treatment does not significantly change the chewing pattern in patients with prognathism regardless of symmetry. The habitual chewing movement may be related to limited mandibular movement, although these movements serve different functions so they are difficult to compare functionally. In this study, there was no significant difference in time-course changes in mandibular motion between SSRO alone and SSRO with Le Fort I osteotomy. Previous studies on functional examination have shown a similar tendency. For the change in maximum mouth opening (MMO), the differences among surgical procedures (SSRO with and without Le Fort I osteotomy, IVRO with and without Le Fort I osteotomy) and the relationship between MMO and the MMF period were examined statistically. Results suggested that there were no significant differences between single-jaw surgery and doublejaw surgery in terms of postoperative time-dependent changes in the recovery of MMO. However, the MMF period was associated with the recovery of MMO.4 For the changes in occlusal force and contact, the difference among surgical procedures (SSRO with and without Le Fort I osteotomy, IVRO with and without Le Fort I osteotomy) was examined statistically. Results suggested that the combination of IVRO or SSRO and Le Fort I osteotomy did not affect postoperative time-dependent changes.27 In conclusion, this study suggests that a postoperative temporary reduction in the border movement of the mandible could recover by 1.5 years postoperative, and the additional procedure of a Le Fort I osteotomy did not affect the recovery of mandibular motion after SSRO. Funding
None.
216
Ueki et al.
Competing interests
None declared. 9.
Ethical approval
Not required.
10.
Patient consent
Not required. 11.
References 1. Stacy GC. Recovery of oral opening following sagittal ramus osteotomy for mandibular prognathism. J Oral Maxillofac Surg 1987;45:487–92. 2. Athanasiou AE. Electrognathographic patterns of mandibular motion after bilateral vertical ramus setback osteotomy. Int J Adult Orthodon Orthognath Surg 1992;7: 23–9. 3. Yang XW, Long X, Yeweng SJ, Kao CT. Evaluation of mandibular setback after bilateral sagittal split osteotomy with Hunsuck modification and miniplate fixation. J Oral Maxillofac Surg 2007;65:2176–80. 4. Ueki K, Marukawa K, Hashiba Y, Nakagawa K, Degerliyurt K, Yamamoto E. Assessment of the relationship between the recovery of maximum mandibular opening and the maxillomandibular fixation period after orthognathic surgery. J Oral Maxillofac Surg 2008;66:486–91. 5. Throckmorton GS, Ellis III E, Sinn DO. Functional characteristics of retrognathic patients before and after mandibular advancement surgery. J Oral Maxillofac Surg 1995;53:898–909. 6. Zarrinkelk HM, Throckmorton GS, Ellis III E, Sinn DP. Functional and morphological alterations secondary to superior repositioning of the maxilla. J Oral Maxillofac Surg 1995;53:1258–67. 7. Song HC, Throckmorton GS, Ellis III E, Sinn DP. Functional and morphological alterations after anterior and/or inferior repositioning of the maxilla. J Oral Maxillofac Surg 1997;55:41–50. 8. Zarrinkelk HM, Throckmorton GS, Ellis III E, Sinn DP. Functional and morphological
12.
13.
14.
15.
16.
17.
18.
19.
changes after combined maxillary intrusion and mandibular advancement surgery. J Oral Maxillofac Surg 1996;54:828–37. Throckmorton GS. Functional deficits in orthognathic surgery patients. Semin Orthod 2006;12:127–37. Nagamine T, Kobayashi T, Nakajima T, Hanada K. The effects of surgical-orthodontic correction of skeletal Class III malocclusion on mandibular movement. J Oral Maxillofac Surg 1993;51:385–9. Tomizawa M, Nakajima T, Ueda K, Azumi T, Hanada K. Evaluation by patients of surgical orthodontic correction of skeletal Class III malocclusion: survey of 41 patients. J Oral Surg 1981;39:590–6. Nagamine T, Kobayashi T, Hanada K, Nakajima T. Satisfaction of patients following surgical-orthodontic correction of skeletal Class III malocclusions. J Oral Maxillofac Surg 1986;44:944–8. Yazdani J, Ebrahimi H, Talesh KT, Khashabi E, Pourshahidi S, Tadbir AA. Comparing the effect of 3 orthognathic surgical methods on the mandibular range of movement. J Craniofac Surg 2010;21:703–5. Shiratsuchi Y, Kouno K, Tashiro H. Evaluation of masticatory function following orthognathic surgical correction of mandibular prognathism. J Craniomaxillofac Surg 1991;19:299–303. Kobayashi T, Honma K, Nakajima T, Hanada K. Masticatory function in patients with mandibular prognathism before and after orthognathic surgery. J Oral Maxillofac Surg 1993;51:997–1001. Raustia AM, Oikarinen KS. Change in electric activity of masseter and temporal muscles after mandibular sagittal split osteotomy. Int J Oral Maxillofac Surg 1994;23:180–4. Ellis E, Throckmorton GS, Sinn DP. Bite forces before and after surgical correction of mandibular prognathism. J Oral Maxillofac Surg 1996;54:176–81. Throckmorton GS, Buschang PH, Ellis E. Improvement of maximum occlusal forces after orthognathic surgery. J Oral Maxillofac Surg 1996;54:1080–6. Kim YG, Oh SH. Effect of mandibular setback surgery on occlusal force. J Oral Maxillofac Surg 1997;55:121–6.
20. Iwase M, Sugimori M, Kurachi Y, Nagumo M. Changes in bite force and occlusal contacts in patients treated for mandibular prognathism by orthognathic surgery. J Oral Maxillofac Surg 1998;56:850–5. 21. Aragon SB, Van Sickels JE, Dolwick MF, Flanary CM. The effects of orthognathic surgery on mandibular range of motion. J Oral Maxillofac Surg 1985;43:938–43. 22. Boyd SB, Karas ND, Sinn DP. Recovery of mandibular mobility following orthognathic surgery. J Oral Maxillofac Surg 1991;49: 924–31. 23. Youssef RE, Throckmorton GS, Ellis III E, Sinn DP. Comparison of habitual masticatory cycle and muscle activity before and after orthognathic surgery. J Oral Maxillofac Surg 1997;55:699–707. 24. Arai K, Ishikawa H. Frontal chewing path incisor point in skeletal Class III patients. J Jpn Orthod Soc 1994;53:154–68. 25. Proschel PA, Hummer H, Hofmann M, Spitzer W. Reaction of mastication to occlusal changes induced by correction of mandibular prognathism. J Prosthet Dent 1990;64:211–8. 26. Ueki K, Marukawa K, Shimada M, Nakagawa K, Yamamoto E, Niizawa S. Changes in the chewing path of patients in skeletal Class III with and without asymmetry before and after orthognathic surgery. J Oral Maxillofac Surg 2005;63:442–8. 27. Ueki K, Marukawa K, Shimada M, Nakagawa K, Yamamoto E. Changes in occlusal force after mandibular ramus osteotomy with and without Le Fort I osteotomy. Int J Oral Maxillofac Surg 2007;36:301–4.
Address: Koichiro Ueki Department of Oral and Maxillofacial Surgery Division of Medicine Interdisciplinary Graduate School of Medicine and Engineering University of Yamanashi 1110 Shimokato Chuo Yamanashi 409-3893 Japan Tel: +81 55 273 9673; Fax: +81 55 273 8210 E-mails: [email protected], [email protected]