Journal of

Oral Rehabilitation

Journal of Oral Rehabilitation 2014 41; 816--821

The influence of bilateral sagittal split ramus osteotomy on submental-cervical aesthetics S. S. SOYDAN*, S. UCKAN†, A. USTDAL‡, B. BAYRAM* & B. BAYRAK§

*Faculty of

Dentistry, Department of Oral and Maxillofacial Surgery, Baskent University, Ankara, †Faculty of Dentistry, Department of Oral and Maxillofacial Surgery, Medipol University, I_ stanbul, ‡Adana Research and Practice Hospital, Department of Orthodontics, Baskent University, Adana, and §Faculty of Dentistry, Department of Oral and Maxillofacial Surgery, Selcuk University, Konya, Turkey

SUMMARY The effect of orthodontic-surgical treatment on submental-cervical region was evaluated in a very limited number of studies. The aim of this study was to evaluate submentalcervical soft tissue contour changes following mandibular advancement and set-back procedures via bilateral sagittal split ramus osteotomy. Sixtyseven patients were included in this study. Group 1 consisted of 27 skeletal Class II patients who underwent mandibular advancement surgery, whereas Group 2 consisted of 40 skeletal Class III patients who underwent mandibular set-back surgery. Various linear and angular measurements were performed on pre-operative and sixth month post-operative cephalometric radiographs. A new method was used to evaluate the amount of sagging at submental region. The submental length did not change in Group 1; however, it decreased significantly in Group 2 (P < 0
05). The angle between submental plane and facial plane decreased to 95
9° from 98
8° in Group 1(P < 0
05),

Introduction Skin laxity, excessive fat tissues, unfavourable musculature configuration, hyoid bone position and the type of dentofacial deformity have a significant effect on submental-cervical aesthetics. Various surgical procedures have been performed to correct the aesthetic problems in this region as the excision of submental skin, lipectomy, platysma muscle alterations, lifting procedures or chin alterations (1–5). Orthognathic surgery is commonly performed not only to get a better occlusion, comfortable chewing or © 2014 John Wiley & Sons Ltd

whereas it increased to 93
1° from 88
2° in Group2 (P < 0
05). The change of submental soft tissue sag was almost stable in Group 1, while 0
34 mm increase of sag was observed in Group 2. This increase was not statistically significant (P > 0
05). Mandibular set-back and advancement procedures do not remarkably change the submental sag following approximately 6 mm jaw movement. Although mandibular advancement did not significantly effect submental length, soft tissue followed mandibular set-back with a ratio of 1:1 at C-point to projection of soft tissue pogonion and 1:0
7 at C-point to soft tissue menton distances. KEYWORDS: submental-cervical aesthetics, submental sag, oral rehabilitation, sagittal split ramus osteotomy, mandibular advancement, mandibular set-back Accepted for publication 29 May 2014

smooth speaking but also to have better facial aesthetic. Predicting soft tissue changes in relation to skeletal movement is an important step in planning of orthognathic surgery (6). Facial deformity usually accompanies with protrusion or retrusion of chin, and therefore, surgical procedure for the correction of the position of the mandible can lead to change of submental-cervical appearance. It can be hypothesised that mandibular advancement and/or anterior autorotation can improve, and mandibular set-back and posterior autorotation may worsenthe submental-cervical contour. The effect of doi: 10.1111/joor.12203

BSSRO & SUBMENTAL-CERVICAL AESTHETICS orthodontic-surgical treatment on submental-cervical region was evaluated in a very limited number of studies (7–11); furthermore, the effect of mandibular surgical movement direction (advancement/set-back) on submental-cervical contour was not previously investigated. The purpose of this study was to evaluate the soft tissue changes on submental-cervical region after bilateral sagittal split ramus osteotomy (BSSRO). Other than comprehensive linear and angular cephalometric measurements, a new method was also described and used to evaluate the amount of submental sag.

Methods This study has been independently reviewed and approved by Baskent University Institutional Review Board and Ethical Committee with Project no: D-KA 12/02. The experiments were undertaken with the understanding and written informed consent of each subject and according to World Medical Association Declaration of Helsinki (version, 2002). The data were derived from lateral cephalometric radiographs of 67 Caucasian patients (38 female and 29 male) with mean age of 26, 31 years (range 18– 39) who underwent orthognathic surgery between 2009 and 2012 by the same surgical team. The selection criteria included: 1 The patients must not have had any previous orthognathic or cosmetic surgery involving the face, increased submental fat tissue by obesity and/or pathological swelling such as submandibular inflammation; 2 No significant maxillary impaction, down fracture or any type of osseous genioplasty were performed; 3 No adjunctive procedure such as liposuction was performed; 4 Standardised cephalograms were taken in natural head position (Patients were told to keep a slight occlusion of the teeth and not executing tongue movement). Patients were divided into two groups considering the mandibular movement direction. Group 1 consisted of 27 (16 female and 11 male) skeletal Class II patients who had mandibular advancement surgery via BSSRO with or without Le Fort I osteotomy. Group 2 consisted of 40 (22 female and 18 male) skeletal Class III patients who had mandibular

© 2014 John Wiley & Sons Ltd

set-back surgery via BSSRO with or without Le Fort I osteotomy. Fourteen patients had mild maxillary impaction ( 0
05). The mean mandibular setback was 5
75 mm (2
8) in Group 2. Statistically significant differences were observed between pre-operative and post-operative values of C-Me’, C-Pg’, GlPg’.CMe’ and SnMe’/CPg’ in Group 2. Following the 5
75 mm mandibular set-back, the mean decrease of C-Me’ was 3
95 mm and C-Pg’ was 5
13 mm. GlPg’.CMe’ increased from 88
27° to 93
12° and SnMe’/CPg’ from 1
3 to 1
5. The mean increase of submental sag was 0
34 mm (P > 0
05).

Discussion Submental area is important for youthful appearance, but it is important to note that younger patients also © 2014 John Wiley & Sons Ltd

BSSRO & SUBMENTAL-CERVICAL AESTHETICS

Fig. 3. The submental sagging was evaluated by measuring of perpendicular distance between the submental plane (C-Me’) and lowermost point of the submental soft tissue contour.

can present with poor submental-cervical aesthetics (14). The possible reasons of poor submental-cervical aesthetics can be listed as a prominent submental fat pad, excessive or flaccid skin, ptotic platysma, large submandibular glands, increased soft tissue chin pad, suprahyoid muscle anatomy and mandibular retrognathia. There are very few studies in the literature regarding the relationship between the submental-cervical soft tissue changes and orthognathic surgery (7–11). Moreno et al. (7). evaluated the cervical plane angle and submental soft tissue thickness at C-point in 16 patients who underwent submental lipectomy or liposuction and various orthognathic surgeries and compared with 16 adults who has ideal submentalcervical aesthetics. Worms et al. (8). indicated the effect of various types of orthodontic–orthognathic corrections on facial profile. Legan and Burstone (9) described the angle between the submental plane and lower facial plane for the cephalometric analysis of the patients who were treated by orthognathic © 2014 John Wiley & Sons Ltd

surgery. Hayes et al. (10) evaluated the change of hyoid bone position, soft tissue correlations at cervicomental region and cervical plane angle in 24 skeletal Class II patients who underwent mandibular advancement surgery. Ghassemi et al. (11) evaluate the effect of mandibular set-back on the cervical region in 34 patients by initial and sixth month post-operative cephalometric radiographs. However, the effect of the mandibular movement direction on submental-cervical aesthetics was not previously documented in the literature. Lateral cephalometric radiographs were routinely taken from each patient 1 week pre-operatively for pre-operative cephalometric setup and 6 months postoperatively for control. Some authors prefer to use the initial cephalometric radiographs in these kind of soft tissue evaluation studies; however, pre-operative cephalometric radiographs should be preferred. Submental-cervical soft tissue contour can change in years during pre-operative orthodontic treatment via growing. Sixth month post-operative radiograph is ideal for evaluation of the impact of orthognathic surgery on soft tissue contour. Post-operative oedema can release and soft tissue adaptation completes in post-operative 6-month period. Some alternative measurements like C-point to menton, perpendicular distance from C-point to projection of soft tissue pogonion, the angle between the facial plane and submental plane, cervical plane angle and lower vertical height–depth ratio were used in current study. A new measurement method was also performed to determine submental sag. In this method, the perpendicular distance between the submental plane and lowermost point of submental soft tissue was evaluated to determine the amount of submental sagging. The change of SnMe’/CPg’ was not statistically significant in mandibular advancement patients; however, the change in SnMe’/CPg’ was statistically significant in set-back patients. A 0
14 increase of the lower vertical height–depth ratio was an expected result in set-back patients because of the statistically significant decrease in the C-Pg’ distance. Even SnMe’/CPg’ increased and deviated from the norm, clinical aesthetic results were grateful in mandibular set-back patients. One of the main criteria of profile view is cervical plane angle. The change of cervical plane angle following orthognathic surgery has been documented in

819

0
003** 0
000** 0
000** 0
002** 0
123 10
61 5
62 6 0
3 1
48 93
12 54
5 67
07 1
5 0
34 10
04 5
25 6
41 0
25 1
33 88
27 58
45 72
2 1
36 0 0
034* 0
872 0
855 0
945 0
859 9
27 7
82 6
98 0
31 1
56 95
98 53
04 65
11 1
55 0
31 10
28 6
54 6
49 0
34 1
56 98
86 52
89 64
94 1
54 0
27 80–95˚ 57  6 mm 62  6 mm 1
2 –

0
068 13
52 121
10 13
11 118
06 0
164 10
67 122
03 10
53 124
77

Std.Dev.() Post-operative value Std.Dev.() Norm value

105–120˚

Cervical plane angle (°) Gl-Pg’/C-Me’(°) C-Me’(mm) C-Pg’(mm) Sn-Me’/C-Pg’ Submental SAG(mm)

Pre-operative value Pre-operative value

Sig.(p)

Group 2 (n = 40) Group 1 (n = 27)

Std.Dev.()

Post-operative value

Std.Dev.()

Sig.

S . S . S O Y D A N et al. Table 1. The norm values, mean pre-operative and post-operative values of all evaluated parameters and results of statistical comparison of pre-operative and post-operative values. Std. Dev: Standard Deviation; *P < 0
05; **P < 0
01

820

only a few norm determination studies (10, 15, 16). Cervical plane angle is used to describe the contour of the transition from submental plane to the anterior aspect of the neck. Hayes et al. (10) reported approximately 1
5° decrease in the cervical plane angle for each millimetre of isolated mandibular advancement. In the present study, the change of cervical plane angle was not statistically significant for both groups. A decrease of 2° was observed in patients who had mandibular advancement and an increase of 3° was observed in mandibular set-back patients. Powell and Humphreys et al. (17) determined the angle between submental plane and facial plane (lip–chin–throat angle) that should be at the range of 80–95°. In the present study, the angle between the facial plane and submental plane decreased to 95
9° from 98
8° in mandibular advancement group (P < 0
05) as it increased to 93
1° from 88
2° in mandibular set-back group (P < 0
05). Approximately 1° increase was observed in accordance with 1 mm mandibular set-back and 0
5° decrease in accordance with 1 mm mandibular advancement. In our study, the C-Me’ and C-Pg’ distances did not change following 6
11 mm mandibular advancement in Group 1, while these distances decreased significantly following 5
75 mm mandibular set-back. This result was compatible with Ghassemi et al.’s findings. Ghassemi et al. (11) also reported significant reduction of cervical length following mandibular set-back. The present study revealed that soft tissue followed mandibular set-back with a ratio of 1:1 at C-Pg’ and 1:0
7 at C-Me’. The position of C-point may follow the bodily movement of the mandible, and submental length approximately remains same in mandibular advancement patients; however, the localisation of the C-point does not change, and submental length decreased in accordance with mandibular set-back. The change of submental sag was first evaluated in the present study, and it was insignificant both in mandibular advancement and set-back patients. A slight increase of submental sag (0
34 mm) was observed in mandibular set-back patients according to significant decrease of submental length; however, it was clinically negligible. The results of present study revealed that 6 mm mandibular set-back lead to a 6% increase of submental sag. Further clinical studies should be design to investigate the prediction of submental sag following excessive (6 mm