A three-dimensional comparison of the pharyngeal airway after mandibular distraction osteogenesis and bilateral sagittal split osteotomy

Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 1632e1637

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A three-dimensional comparison of the pharyngeal airway after mandibular distraction osteogenesis and bilateral sagittal split osteotomy €mmerer c, Gerhard Scho € n d, Reinhard Bschorer b Daniel Schneider a, b, *, Peer W. Ka €dtmann & Dr. Herzog, Rostock, Germany Oral and Maxillofacial Surgery e Partnership Dr. To Department of Oral and Maxillofacial Surgery, HELIOS Kliniken Schwerin (Head: Univ.-Prof. Dr. Dr. Reinhard Bschorer MD, DDS, PhD), Wismarsche Strabe 393-397, 19049 Schwerin, Germany c Department of Oral, Maxillofacial and Plastic Surgery, University Medical Center of Rostock, Germany d Department of Medical Biometry and Epidemiology, University Medical Center Hamburg-Eppendorf, Germany a

b

a r t i c l e i n f o

a b s t r a c t

Article history: Paper received 23 March 2015 Accepted 21 July 2015 Available online 29 July 2015

Purpose: The goal of this retrospective study was to examine the radiological changes in the pharyngeal airway following mandibular distraction osteogenesis (DO) and bilateral sagittal split osteotomy (BSSO). Material and methods: Between 2005 and 2009, a total of 41 nonsyndromic patients underwent a mandibular osteotomy (nDO ¼ 23; nBSSO ¼ 18). Digital volume tomography images were created for preoperative and postoperative evaluations of both groups. The Dolphin 3D program was used for comparative analysis of the pharyngeal airways. Results: After DO, the airway volumes (VOL) improved by 6.8 mL. In comparison, an improvement of 5.9 mL was observed as result of BSSO. The minimum axial areas (AREA) of the enlargements increased by 109.1 mm2 with DO and 103.1 mm2 with BSSO. The airway areas (SA) increased by 193.8 mm2 with DO and 185.2 mm2 with BSSO. There were no significant differences between two surgical procedures in terms of the parameters describe above (pVOL ¼ 0.358; pAREA ¼ 0.752; pSA ¼ 0.777). However, the initial preoperative values (pVOL ¼ 0.020; pAREA ¼ 0.005) and the patients' ages (pAREA ¼ 0.042; pSA ¼ 0.007) did have significant effects on the postoperative values. Conclusion: Both DO and BSSO expanded the pharyngeal airways of all nonsyndromic patients. © 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

Keywords: Mandibular distraction osteogenesis Bilateral sagittal split osteotomy Orthognathic surgery Pharyngeal airway Upper airway Airway change

1. Introduction In orthognathic surgery, it is generally accepted that the forward motion of the mandible has an advantageous effect on the expansion of the airway in the pharyngeal area (Lee et al., 2014). Bilateral sagittal split osteotomy (BSSO) is an accepted treatment option for the advancement of mandible (Geha et al., 2006; Monson, 2013). However, some studies have reported complications, such as impairment of the inferior alveolar nerve (Mensink et al., 2012; AlNawas et al., 2014; Baas et al., 2015), the possibility of growth disabilities, as well as postoperative relapse (Gassmann et al., 1990;

* Corresponding author. Strempelstraße 6, 18057 Rostock, Germany. Tel.: þ49 385 520 30 80; fax: þ49 385 520 30 77. E-mail addresses: [email protected] (D. Schneider), reinhard. [email protected] (R. Bschorer).

Schreuder et al., 2007; Ow and Cheung, 2010a). The cause of the relatively high rate of relapse seems to be the acute stretching of soft tissue, including muscles and tendons (van Strijen et al., 2004; Vos et al., 2009). Mandibular distraction osteogenesis (DO) is an alternative procedure to BSSO. DO was first mentioned in the medical literature in the beginning of the 20th century. The Russian Ilizarov is credited with its popularization as early as the 1950s; he established the method for the extension of the extremities (Ilizarov, 1989). In the following decade, the initial experimental animal studies focused on the extension of the mandible. In 1992, McCarthy et al. performed the first mandibular distraction osteogenesis in a human patient (McCarthy et al., 1992). The gentler, gradual stretching of the soft tissue appears to be an advantage of DO (Schreuder et al., 2007). With DO, longer distances of gradual movement are also possible. Additionally, high levels of stability with precise settings of the occlusion are possible when the patient is awake (Schreuder et al., 2007). The medical literature describes

http://dx.doi.org/10.1016/j.jcms.2015.07.014 1010-5182/© 2015 European Association for Cranio-Maxillo-Facial Surgery. Published by Elsevier Ltd. All rights reserved.

D. Schneider et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 1632e1637

another possible advantage of DO, namely, the reduced possibility of nerve damage (Ow and Cheung, 2010a,b). Distraction is also possible for child patients (Baas et al., 2010; Abramson et al., 2013). Both surgical methods lead to improvements in occlusion, chewing functions, and facial aesthetics. Since 1979, the enlargement of the pharyngeal airway has been accepted as a result of BSSO (Kuo et al., 1979; Agbaje et al., 2014). This result is relevant because mandibular retrognathia is usually associated with small, irregularly formed airways (El and Palomo, 2011). This condition significantly increases patient morbidity and mortality (Kim et al., 2010; Okushi et al., 2011; Abramson et al., 2013). Mandibular distraction osteogenesis has subsequently become an accepted alternative to tracheostomy and to BSSO or maxillomandibular advancement (Verse et al., 2009; Ubaldo et al., 2015). The aim of the present study was to analyze and compare the radiological changes in the pharyngeal airway following bilateral sagittal split osteotomy and mandibular distraction osteogenesis. Secondary aims were an evaluation of the influence of patient gender, age, and initial value on differences between the preoperative and postoperative airway values. 2. Material and methods Within the scope of this retrospective, noninterventional caseecontrol study, a total of 41 nonsyndromic patients were analyzed between 2005 and 2009. Data were collected case-specifically after the examination of the completeness of the patient's files and a digital body imaging procedure. Inclusion criteria were patients with a mandibular retrognathia who were treated via mandibular orthognathic surgery by DO or BSSO in the Department of Oral and Maxillofacial Surgery at the HELIOS Kliniken Schwerin during the period. Exclusion criteria of this study were as follows: patients with incomplete medical record and missing data from the hospital database; and patients with another treatment or incomplete digital volume tomography images. The following data were collected from a total of 27 (70.7%) female and 12 (29.3%) male patients. The average age was 31.6 years, and the median was 32.1 years. The minimum patient age was 17.8 years, and the maximum patient age was 52.1 years. Of these patients, 23 (56.1%) were treated with DO, and 18 (43.9%) were treated with BSSO. The average advancement of the BSSO patients was 7.4 mm. The average displacement length of the DO patients was 10.7 mm. Digital volume tomographic images were created for preoperative and postoperative evaluations of both groups. To increase the reproducibility, anatomical radiological landmarks were defined. Additionally, the upper and lower boundaries of the pharyngeal airway were determined. For each patient, the airway volume (VOL) [mL], the sagittal airway area (SA) [mm2], and the minimum axial area (AREA) [mm2] were recorded in the data set (Table 1).

The respiratory volume was evaluated using the Dolphin 3D program (Fig. 1). All calculations were made using the statistical program R Version 3.1.0. Significant differences between the improvements in the two surgical procedure groups were statistically tested. The study pursued the following questions: Did the initial values, patient genders, or patient ages affect the differences between the two groups? Linear regressions were calculated based on the differences between the two measurement points (dependent variable) and the grouping variables of the patient gender, age, and the initial value (independent variable). 3. Results 3.1. Comparison of measurements before and after mandibular distraction osteogenesis and bilateral sagittal split osteotomy The preoperative average values of the airway volumes were 16.1 mL (median 14.6 mL) for the DO group and 14.3 mL (median 11.8 mL) for the BSSO group. The postoperative average values were 22.9 mL (median 21.2 mL) for the DO group and the 20.2 mL (median 17.7 mL) for the BSSO group. The average improvements in the airway volumes were 6.8 mL for the DO group and 5.9 mL for the BSSO group. The difference was 0.87 mL (confidence interval [CI] ¼ 1.02e2.76). Therefore, there was no significant difference (p ¼ 0.358) (Table 2, Fig. 2). The average initial value for the minimal axial areas for the DO group was 150.9 mm2 (median 142.3 mm2). The average value before surgery for the BSSO group was 147.9 mm2 (median 144.8 mm2). The postoperative averages were 260.1 mm2 (median 265.0 mm2) for the DO group and 250.9 mm2 (median 252.9 mm2) for the BSSO group. The minimum axial areas improved by an average of 109.1 mm2 for the DO group and an average of 103.1 mm2 for the BSSO group. The difference of 6.05 mm2 (CI ¼ 32.42e44.52) between the two groups was not significant (p ¼ 0.752) (Table 3; Fig. 3). The preoperative average values for the airway areas were 553.2 mm2 (median 573.7 mm2) for the DO group and 551.2 mm2 (median 526.5 mm2) for the BSSO group. The DO group reached a postoperative average airway area value of 747.0 mm2 (median 763.2 mm2), whereas the BSSO group reached an average value of 736.4 mm2 (median 689.4 mm2). The airway area of the DO group improved by an average of 193.8 mm2. The average improvement of the BSSO group was 185.2 mm2. The difference of 8.61 mm2 (CI ¼ 52.39e69.61) was not significant (p ¼ 0.777) (Table 4, Fig. 4). 3.2. Influence of initial preoperative value and patient gender and age A linear regression model was calculated to simultaneously examine the effects of group, preoperative value, gender, and age

Table 1 Defined limiting points, determined limits of the pharyngeal airway to be measured, and the determined parameters in the data set. Boundary points Boundary points/Determined parameters

Definition

BA (Basion) PNS (Posterior nasal spine) C3 V (Vallecula) BA e PNS C3 e V Airway volume (VOL) [mL] Airway area (SA) [mm2] Minimum axial area (AREA) [mm2]

The furthest lying posterior-inferior point in front of the foramen magnum The furthest posterior point of the hard (bony) palate The furthest anterior-inferior point of the third cervical vertebra The cross-section of the epiglottis and the base of the tongue The upper boundary of the pharyngeal airway to be measured The lower boundary of the pharyngeal airway to be measured The total airway volume between the upper and lower boundary The sagittal airway area between the upper and lower boundary Calculated by the software

Modified from Valladares-Neto et al., 2013.

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Fig. 2. Enlargements of the airway volumes [mL] (before and after surgery) for the DO and BSSO procedures shown for each individual case. The airway volumes increased by averages of 6.8 mL for the DO group and. 5.9 mL for the BSSO group. The difference was 0.87 mL (confidence interval ¼ 1.02e2.76; p ¼ 0.358).

Fig. 1. Measurement factors from the Dolphin 3D program. The upper boundary between the BA and PNS and the lower boundary of the pharyngeal airway between C3 and V can be clearly identified. The determined airway area is shown in bright pink in the upper picture. The determined airway volume is presented in a three-dimensional bright pink dye in the lower picture. The minimum axial area is marked in green in the lower picture [Source: Dolphin 3D© DO patient].

on the differences both before and after surgery. Statistically, the airway volume of the BSSO group increased by an average of 0.87 mL (CI ¼ 1.02e2.76) less than that of the DO group (Table 2, Fig. 2). However, this increase was possibly due to patient age, gender, or initial values. We next examined the group difference while accounting for these variables. After controlling for these variables, the BSSO group's average increase in airway volume was 0.69 mL (CI ¼ 2.48e1.10) less than that of the other group. This

finding indicates that a portion of the difference was not dependent on group differences but, rather, was dependent on additional variables. However, the difference was still not significant (p ¼ 0.441). Furthermore, patient age (p ¼ 0.381) and gender (p ¼ 0.346) had no influence on the difference before and after surgery. However, the initial preoperative values (p ¼ 0.020) did affect the difference. Therefore, a 0.25 mL (CI ¼ 0.04e0.46) increase in the difference (dependent variable) in the airway volume was expected for each increase in the initial value of 1 (Table 5). In terms of the minimum axial area, the group difference changed. This difference was now 1.82 mm2 (CI ¼ 34.46e38.10) for the BSSO group. Here, the difference was also not caused solely by a group difference. The initial preoperative value of the minimum axial area affected (p ¼ 0.005) the difference before and after surgery. Therefore, a 6.19 mm2 (CI ¼ 1.97e10.42) increase in the difference (dependent variable) of the minimum axial area was expected for every additional unit by which the initial value increased. Patient age also influenced the difference before and

Table 2 Comparison of the airway volumes [mL] before and after surgery according to surgical procedure. Airway volume [mL] Parameter

DO Before surgery After surgery BSSO Before surgery After surgery

Mean

CI

Median

SD

Minimum

Maximum

18.2 25.8

14.6 21.2

4.9 6.6

8.4 12.1

25.7 38.6

17.0 24.1

11.8 17.7

5.3 7.7

8.1 10.1

24.3 35.6

Min

Max

16.1 22.9

14.0 20.1

14.3 20.2

11.7 16.4

CI, confidence interval; Max, maximum; Min, minimum; SD, standard deviation. t-Test DO after minus DO before. Difference (CI): 6.82 (5.63e8.00), p < 0.001. t-Test BSSO after minus BSSO before. Difference (CI): 5.94 (4.33e7.56), p < 0.001. t-Test difference between the differences between DO und BSSO. Difference (CI): 0.87 (1.02e2.76), p ¼ 0.358.

D. Schneider et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 1632e1637 Table 3 Comparison of the minimum axial areas [mm2] before and after surgery according to surgical procedure. Minimum axial area [mm2] Parameter

Mean

Table 4 Comparison of the airway areas [mm2] before and after surgery according to surgical procedure. Airway area [mm2]

CI Min

DO Before surgery After surgery BSSO Before surgery After surgery

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Median

SD

Min

Max

Parameter

Mean

Max

150.9 260.1

122.7 218.3

179.1 301.8

142.3 265.0

65.2 96.5

66.4 53.9

365.7 476.4

147.9 250.9

123.2 203.9

172.6 298.0

144.8 252.9

49.7 94.6

74.1 109.2

217.0 400.7

CI, confidence interval; Max, maximum; Min, minimum; SD, standard deviation. t-Test DO after minus before. Difference (CI): 109.13, (81.29e136.96), p < 0.001. t-Test BSSO after minus before. Difference (CI): 103.08, (75.76e130.39), p < 0.001. t-Test difference between the differences between DO und BSSO. Difference (CI): 6.05 (32.42e44.52), p ¼ 0.752.

after surgery (p ¼ 0.042). Therefore, a 1.99 mm2 (CI ¼ 0.08e3.90) increase in the difference (dependent variable) of the minimum axial area was expected for every year added to the patient's age. However, gender did not influence the values (p ¼ 0.836) (Table 5). Examination of the airway area revealed shows a 8.04-mm2 (CI ¼ 69.42e53.33) smaller average increase for the BSSO group. Here, the difference was not caused solely by group differences either. The age of the SA patients had a significant effect on the difference before and after surgery (p ¼ 0.007). Therefore, a 4.57 mm2 (CI ¼ 1.34e7.80) increase in the difference between the measuring points (dependent variable) of the SA rate was expected for every year added to the patient's age. The initial preoperative values (p ¼ 0.175) and gender (p ¼ 0.838) had no significant influence (Table 5).

Fig. 3. Enlargements of the minimum axial areas [mm2] (before and after surgery) for the DO and BSSO groups shown for each individual case. The minimum axial areas increased by averages of 109.1 mm2 for the DO group and 103.1 mm2 for the BSSO group. The difference between the two groups was 6.05 mm2 (confidence interval ¼ 32.42e44.52; p ¼ 0.752).

DO Before surgery After surgery BSSO Before surgery After surgery

CI

Median

SD

Min

Max

Min

Max

553.2 747.0

501.6 674.1

604.9 819.9

573.7 763.2

119.5 168.6

272.8 432.1

749.5 989.2

551.2 736.4

490.3 650.6

612.2 822.2

526.5 689.4

122.5 172.5

367.1 482.5

740.8 989.2

CI, confidence interval; Max, maximum; Min, minimum; SD, standard deviation. t-Test DO after minus before. Difference (CI): 193.78 (154.28e233.29), p < 0.001. t-Test BSSO after minus before. Difference (CI): 185.17 (134.78e235.56), p < 0.001. t-Test difference between the differences between DO und BSSO. Difference (CI): 8.61, (52.39e69.61), p-value: 0.777.

4. Discussion The present study examined the pharyngeal airway after DO and compared the results to those after BSSO. The study confirmed that DO of the mandible affects the pharyngeal airway (Ow and Cheung, 2008). Furthermore, DO is highly successful and therefore causes definitive repair of airways that, preoperatively, considered to be too small (Rachmiel et al., 2005). Both DO and BSSO enlarged the pharyngeal airway in all patients in the study. The expansion of the airway volume following DO averaged 6.8 mL (vs. 5.9 mL for BSSO); the expansion of the minimum axial area averaged 109.1 mm2 (vs. 103.1 mm2 for BSSO); and the expansion of the airway area averaged 193.8 mm2 (vs. 185.2 mm2 for BSSO; Tables 2e4). However, no significant differences between the two surgical procedures were found in terms of the parameters mentioned above. For both

Fig. 4. Enlargements of the airway areas [mm2] (before and after surgery) following DO and BSSO shown for each individual case. The airway areas were enlarged by averages of 193.8 mm2 for the DO group and 185.2 mm2 in the BSSO group. The difference between the two groups was 8.61 mm2 (confidence interval ¼ 52.39e69.61; p ¼ 0.777).

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Table 5 Changes in differences between measurement time points compared to initial value according to patient gender and age. Group comparison Parameter

Coefficient

CI Min

Airway volume [mL] Group BSSO 0.69 Pre VOL 0.25 Sex: male 1.09 Age 0.04 Minimum axial area [mm2] Group BSSO 1.82 Pre AREA 6.19 Sex: male 4.84 Age 1.99 Airway area [mm2] Group BSSO 8.04 Pre SA 4.87 Sex: male 8.08 Age 4.57

p-Value Max

2.48 0.04 1.23 0.05

1.10 0.46 3.41 0.14

0.441 0.020 0.346 0.381

34.46 1.97 51.77 0.08

38.10 10.42 42.10 3.90

0.919 0.005 0.836 0.042

69.42 2.27 87.47 1.34

53.33 12.01 71.32 7.80

0.792 0.175 0.838 0.007

CI, confidence interval; Max, maximum; Min, minimum; SD, standard deviation. p-Value is of the linear regression.

surgical procedures and all patients, the airway volume increased by an average of 6.4 mL. The initial preoperative values (pVOL ¼ 0.020; pAREA ¼ 0.005) and patient age (pAREA ¼ 0.042; pSA ¼ 0.007) did have significant effects on the postoperative values. The medical literature suggests that the expansion of the airway in the pharynx area is affected more by the forward movement of the mandible than by that of the maxilla. The results of this study indicated that the forward movement of the mandible led to an expansion of the pharyngeal airway in all cases (Gale et al., n et al., 2011; Herna ndez-Alfaro et al., 2011) (Table 5). 2000; Folta Various types of therapy such as conservative (e.g., weight reduction or sleep hygiene), equipment-based (e.g., continuous positive airway pressure [CPAP] or mandibular protrusion splints) and surgical procedures are described for treatment of obstructive sleep apnea. The first-line therapy should be conservative, via CPAP plus weight and alcohol consumption management. However, nonsurgical procedures depend significantly on patient compliance and thus are limited in clinical effectiveness (Elshaug et al., 2008; Certal et al., 2013; Weaver et al., 2014; White, 2014). Therefore, the correction of obstructive sleep apnea by surgery plays an important role when medical management is not tolerated or is refractive (Schendel et al., 2014). Literature research demonstrated that BSSO is a better investigated surgical procedure to expand the upper airways than is DO (Verse et al., 2009; Jakobsone et al., 2011; Alolayan and Leung, 2014). Although there were no significant differences in airway expension when comparing BSSO and DO, the present study provides evidence for DO as a valuable alternative method for this purpose. Numerous recent studies that have examined the pharyngeal airway after orthognathic surgery via lateral cephalometric body imaging, which is limited in terms of its evaluative capabilities due to two-dimensionality (Waite et al., 1989; Mehra et al., 2001; Aboudara et al., 2009). A recent study by Valladares-Neto et al. analyzed the pharyngeal airway using a three-dimensional examination method (Valladares-Neto et al., 2013). These authors reported an average expansion of the pharyngeal airway of 7.8 mL (present study: DO 6.8 mL, BSSO 5.9 mL) during Le Fort I osteotomy and BSSO. Furthermore, an increase in the minimum axial area of 114.3 mm2 (present study: DO 109.1 mm2, BSSO 103.1 mm2) was reported. These findings are in accordance with reports in the ndez-Alfaro et al., 2011; Valladares-Neto et al., literature (Herna 2013).

However, the evaluation method used in the current study, the Dolphin 3D program, should be discussed critically. According to a study by Water et al. (de Water et al., 2014), this software is inaccurate and lacks dependability. The authors examined the effects of Le Fort III osteotomy on the airway and the differences between the Dolphin 3D©and manual segmentation software systems. Inaccuracies were observed only in relation to very small preoperative airways and resolved themselves with larger airway volumes. Other authors have not confirmed this inaccuracy. The precision and accuracy of this program must be determined for future studies (Weissheimer et al., 2012; Alves et al., 2012). Earlier studies have reported forward movement of the mandible of 10 mm or more using distraction osteogenesis, without any complications. This distance is possible without substantially increasing risk of injury to the inferior alveolar nerve. Based on the findings of Ow and Cheung and Al-Nawas et al., the incidences of persistent inferior alveolar nerve dysfunction are 2.9% for DO (Ow and Cheung, 2009) and 27.8% for BSSO (Ow and Cheung, 2009) and early nerve lesion 11.2% (Al-Nawas et al., 2014) for BSSO. Ow and Cheung also indicated a higher incidence of condylar resorption for BSSO (6.1%) compared with DO (1.4%) (Ow and Cheung, 2009). In conclusion, both mandibular distraction osteogenesis and bilateral sagittal split osteotomy expand the pharyngeal airway. Undoubtedly, DO should be regarded as a treatment of equal value, although it has the possible advantage of a gentler displacement (van Strijen et al., 2004; Whitesides and Meyer, 2004). This potential advantage should be further examined in the future. Additionally, as it was not the aim of this study to analyze the correlation between displacement length and the expansion of the pharyngeal airway, this issue should be examined in future studies as well. Such studies could examine the correlation in relation to complications during both procedures, and the connection between the advancement of the mandible and the expansion of the pharyngeal airway volume. 5. Conclusion In all cases, the applied mandibular distraction osteogenesis expanded the pharyngeal airways and was demonstrated to be a stable procedure. Thus, DO is clearly established as an alternative treatment method for expanding the pharyngeal airways of nonsyndromic patients and should therefore be used in appropriate cases. Conflict of interest Professor Dr. med. Dr. med. dent. R. Bschorer was involved in the development of using distractor in present study (Zurich Distractor II; KLS Martin GmbH & Co., Tuttlingen, Germany). The other authors have no conflicts of interest to disclose. References Aboudara C, Nielsen I, Huang JC, Maki K, Miller AJ, Hatcher D: Comparison of airway space with conventional lateral headfilms and 3-dimensional reconstruction from cone-beam computed tomography. Am J Orthod Dentofacial Orthop 135: 468e479, 2009 Abramson ZR, Susarla SM, Lawler ME, Peacock ZS, Troulis MJ, Kaban LB: Effects of mandibular distraction osteogenesis on three-dimensional airway anatomy in children with congenital micrognathia. J Oral Maxillofac Surg 71: 90e97, 2013 Agbaje JO, Salem AS, Lambrichts I, Jacobs R, Politis C: Systematic review of the incidence of inferior alveolar nerve injury in bilateral sagittal split osteotomy and the assessment of neurosensory disturbances. Int J Oral Maxillofac Surg 44: 447e451, 2015 Al-Nawas B, K€ ammerer PW, Hoffmann C, Moergel M, Koch FP, Wriedt S, et al: Influence of osteotomy procedure and surgical experience on early complications after orthognathic surgery in the mandible. J Craniomaxillofac Surg 42: e284ee288, 2014 Alolayan AB, Leung YY: Risk factors of neurosensory disturbance following orthognathic surgery. PLoS One 9: e91055, 2014

D. Schneider et al. / Journal of Cranio-Maxillo-Facial Surgery 43 (2015) 1632e1637 Alves M, Baratieri C, Mattos CT, Brunetto D, Fontes Rda C, Santos JR, Ruellas AC: Is the airway volume being correctly analyzed? Am J Orthod Dentofac Orthop 141: 657e661, 2012 Baas EM, de Lange J, Horsthuis RBG: Evaluation of alveolar nerve function after surgical lengthening of the mandible by a bilateral sagittal split osteotomy or distraction osteogenesis. Int J Oral Maxillofac Surg 39: 529e533, 2010 Baas EM, Bierenbroodspot F, de Lange J: Bilateral sagittal split osteotomy versus distraction osteogenesis of the mandible: a randomized clinical trial. Int J Oral Maxillofac Surg 44: 180e188, 2015 Certal V, Nishino N, Camacho M, Capasso R: Reviewing the systematic reviews in OSA surgery. Otolaryngol Head Neck Surg 149: 817e829, 2013 El H, Palomo JM: Airway volume for different dentofacial skeletal patterns. Am J Orthod Dentofacial Orthop 139: e511ee521, 2011 Elshaug AG, Moss JR, Hiller JE, Maddern GJ: Upper airway surgery should not be first line treatment for obstructive sleep apnoea in adults. BMJ Clin Res Ed 336: 44e45, 2008  G, Hanzelka T, Klíma K, Hork Folt an R, Hoffmannov a J, Pavlíkova a E, et al: The influence of orthognathic surgery on ventilation during sleep. Int J Oral Maxillofac Surg 40: 146e149, 2011 Gale DJ, Sawyer RH, Woodcock A, Stone P, Thompson R, O'Brien K: Do oral appliances enlarge the airway in patients with obstructive sleep apnoea? A prospective computerized tomographic study. Eur J Orthod 22: 159e168, 2000 Gassmann CJ, Van Sickels JE, Thrash WJ: Causes, location, and timing of relapse following rigid fixation after mandibular advancement. J Oral Maxillofac Surg 48: 450e454, 1990 Geha HJ, Gleizal AM, Nimeskern NJ, Beziat J: Sensitivity of the inferior lip and chin following mandibular bilateral sagittal split osteotomy using piezosurgery. Plast Reconstruct Surg 118: 1598e1607, 2006 ndez-Alfaro F, Guijarro-Martínez R, Mareque-Bueno J: Effect of mono- and Herna bimaxillary advancement on pharyngeal airway volume: cone-beam computed tomography evaluation. J Oral Maxillofac Surg 69: e395e400, 2011 Ilizarov GA: The tension-stress effect on the genesis and growth of tissues. Part I. The influence of stability of fixation and soft-tissue preservation. Clin Orthop Relat Res: 249e281, 1989 Jakobsone G, Stenvik A, Espeland L: The effect of maxillary advancement and impaction on the upper airway after bimaxillary surgery to correct class III malocclusion. Am J Orthod Dentofacial Orthop 139: e369ee376, 2011 Kim J, Kim JK, Hong S, Cho JH: Pharyngeal airway changes after sagittal split ramus osteotomy of the mandible: a comparison between genders. J Oral Maxillofac Surg 68: 1802e1806, 2010 Kuo PC, West RA, Bloomquist DS, McNeil RW: The effect of mandibular osteotomy in three patients with hypersomnia sleep apnea. Oral Surg Oral Med Oral Pathol 48: 385e392, 1979 Lee SH, Kaban LB, Lahey ET: Skeletal stability of patients undergoing maxillomandibular advancement for treatment of obstructive sleep apnea. J Oral Maxillofac Surg 73: 694e700, 2015 McCarthy JG, Schreiber J, Karp N, Thorne CH, Grayson BH: Lengthening the human mandible by gradual distraction. Plast Reconstr Surg 89: 1e8, 1992 discussion 9e10 Mehra P, Downie M, Pita MC, Wolford LM: Pharyngeal airway space changes after counterclockwise rotation of the maxillomandibular complex. Am J Orthod Dentofacial Orthop 120: 154e159, 2001 Mensink G, Zweers A, Wolterbeek R, Dicker Gertjan GJ, Groot RH, van Merkesteyn Richard JPR: Neurosensory disturbances one year after bilateral sagittal split osteotomy of the mandibula performed with separators: a multicentre prospective study. J Cranio-Maxillo-Fac Surg 40: 763e767, 2012 Monson LA: Bilateral sagittal split osteotomy. Semin Plast Surg 27: 145e148, 2013 Okushi T, Tonogi M, Arisaka T, Kobayashi S, Tsukamoto Y, Morishita H, et al: Effect of maxillomandibular advancement on morphology of velopharyngeal space. J Oral Maxillofac Surg 69: 877e884, 2011

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Ow A, Cheung LK: Meta-analysis of mandibular distraction osteogenesis: clinical applications and functional outcomes. Plast Reconstruct Surg 121: 54ee69e, 2008 Ow A, Cheung LK: Skeletal stability and complications of bilateral sagittal split osteotomies and mandibular distraction osteogenesis: an evidence-based review. J Oral Maxillofac Surg 67: 2344e2353, 2009 Ow A, Cheung LK: Bilateral sagittal split osteotomies and mandibular distraction osteogenesis: a randomized controlled trial comparing skeletal stability. Oral Surg Oral Med Oral Pathol Oral Radiol Endod 109: 17e23, 2010a Ow A, Cheung LK: Bilateral sagittal split osteotomies versus mandibular distraction osteogenesis: a prospective clinical trial comparing inferior alveolar nerve function and complications. Int J Oral Maxillofac Surg 39: 756e760, 2010b Rachmiel A, Aizenbud D, Pillar G, Srouji S, Peled M: Bilateral mandibular distraction for patients with compromised airway analyzed by three-dimensional CT. Int J Oral Maxillofac Surg 34: 9e18, 2005 Schendel SA, Broujerdi JA, Jacobson RL: Three-dimensional upper-airway changes with maxillomandibular advancement for obstructive sleep apnea treatment. Am J Orthodont Dentofac Orthop 146: 385e393, 2014 Schreuder WH, Jansma J, Bierman MWJ, Vissink A: Distraction osteogenesis versus bilateral sagittal split osteotomy for advancement of the retrognathic mandible: a review of the literature. Int J Oral Maxillofac Surg 36: 103e110, 2007 Ubaldo ED, Greenlee GM, Moore J, Sommers E, Bollen A: Cephalometric analysis and long-term outcomes of orthognathic surgical treatment for obstructive sleep apnoea. Int J Oral Maxillofac 44: 752e759, 2015 Valladares-Neto J, Silva MAG, Bumann A, Paiva JB, Rino-Neto J: Effects of mandibular advancement surgery combined with minimal maxillary displacement on the volume and most restricted cross-sectional area of the pharyngeal airway. Int J Oral Maxillofac Surg 42: 1437e1445, 2013 van Strijen PJ, Breuning KH, Becking AG, Tuinzing DB: Stability after distraction osteogenesis to lengthen the mandible: results in 50 patients. J Oral Maxillofac Surg 62: 304e307, 2004 Verse T, Bodlaj R, de la Chaux R, Dreher A, Heiser C, Herzog M, Hohenhorst W, €rmann K, Kaschke O, Kühnel T, Mahl N, Maurer JT, Pirsig W, Rohde K, Ho Sauter A, Schedler M, Siegert R, Steffen A, Stuck BA, ArGe Schlafmedizin der Deutschen Gesellschaft für Hals-Nasen-Ohren-Heilkunde, Kopf- und HalsChirurgie: Guideline: treatment of obstructive sleep apnea in adults. HNO 57: 1136e1156, 2009 Vos MD, Baas EM, de Lange J, Bierenbroodspot F: Stability of mandibular advancement procedures: bilateral sagittal split osteotomy versus distraction osteogenesis. Int J Oral Maxillofac Surg 38: 7e12, 2009 Waite PD, Wooten V, Lachner J, Guyette RF: Maxillomandibular advancement surgery in 23 patients with obstructive sleep apnea syndrome. J Oral Maxillofac Surg 47: 1256e1261, 1989 discussion 1262 de Water VR, Saridin JK, Bouw F, Murawska MM, Koudstaal MJ: Measuring upper airway volume: accuracy and reliability of Dolphin 3D software compared to manual segmentation in craniosynostosis patients. J Oral Maxillofac Surg 72: 139e144, 2014 Weaver TE, Calik MW, Farabi SS, Fink AM, Galang-Boquiren MT, Kapella MC, et al: Innovative treatments for adults with obstructive sleep apnea. Nat Sci Sleep 6: 137e147, 2014 Weissheimer A, Menezes LM, Sameshima GT, Enciso R, Pham J, Grauer D: Imaging software accuracy for 3-dimensional analysis of the upper airway. Am J Orthod Dentofacial Orthop 142: 801e813, 2012 White DP: New therapies for obstructive sleep apnea. Semin Respir Crit Care Med 35: 621e628, 2014 Whitesides LM, Meyer RA: Effect of distraction osteogenesis on the severely hypoplastic mandible and inferior alveolar nerve function. J Oral Maxillofac Surg 62: 292e297, 2004