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2016 ghassemi-maxillary advancement versus man
1. YIJOM-3562; No of Pages 7
Please cite this article in press as: Ghassemi M, et al. Maxillary advancement versus mandibular setback in class III dentofacial
deformity: are there any differences in aesthetic outcomes?, Int J Oral Maxillofac Surg (2016), http://dx.doi.org/10.1016/
Clinical Paper
Orthognathic Surgery
Maxillary advancement versus
mandibular setback in class III
dentofacial deformity: are there
any differences in aesthetic
outcomes?
M. Ghassemi, R.-D. Hilgers, U. Fritz, A. Modabber, A. Ghassemi: Maxillary
advancement versus mandibular setback in class III dentofacial deformity: are there
any differences in aesthetic outcomes?. Int. J. Oral Maxillofac. Surg. 2016; xxx: xxx–
xxx. # 2016 International Association of Oral and Maxillofacial Surgeons. Published
by Elsevier Ltd. All rights reserved.
M. Ghassemi1
, R.-D. Hilgers2
,
U. Fritz1
, A. Modabber3
,
A. Ghassemi4
1
Department of Orthodontics, RWTH Aachen
University, Aachen, Germany; 2
Department of
Medical Statistics, RWTH Aachen University,
Aachen, Germany; 3
Department of Oral and
Maxillofacial Surgery, RWTH Aachen
University, Aachen, Germany; 4
Oral and
Maxillofacial Surgery, Klinikum-Lippe,
Detmold, Germany
Abstract. A retrospective evaluation of maxillary advancement and mandibular
setback in class III patients was performed and their aesthetic outcomes compared.
Patients with a sella–nasion–A-point angle (SNA) of 80–848 were selected. Pre- and
postoperative lateral cephalograms were obtained for 34 class III patients; these
were divided into two groups according to the surgical procedure performed:
mandibular setback group (n = 17) and maxillary advancement group (n = 17). The
pre- and postoperative cervical length, lip–chin–throat angle, lower/upper lip
thickness, distance from the lower/upper lip to the aesthetic line, soft tissue angle,
facial contour angle, and nasolabial angle of the two groups were compared.
Significant differences were observed for cervical length (P = 0.0003) and sex
(P = 0.003) when comparing maxillary advancement with mandibular setback.
Although the preoperative cervical length was similar in the two groups, it increased
significantly after maxillary advancement and decreased after mandibular setback.
In this study, the differences in aesthetic outcomes depending on the surgical
procedure performed were considered. Some aesthetically important parameters
proved to be superior after maxillary advancement when compared to mandibular
setback, even with the maxilla in the normal position.
Key words: Class III deformity; maxillary ad-
vancement versus mandibular setback; soft
tissue outcome.
Accepted for publication 29 November 2016
Class III malocclusion is considered one of
the most complex conditions in terms of
diagnosis and treatment planning, and an
increasing demand for surgical correction
has been observed in recent years.1–3
Treat-
ment should include the following goals:
function, aesthetics, long-term stability,
and the selection of the procedure with
the lowest complication rate. The anatomi-
cal feasibility should also be considered.
The level of patient satisfaction is an
important factor that has a significant
Int. J. Oral Maxillofac. Surg. 2016; xxx: xxx–xxx
http://dx.doi.org/10.1016/j.ijom.2016.11.017, available online at http://www.sciencedirect.com
0901-5027/000001+07 # 2016 International Association of Oral and Maxillofacial Surgeons. Published by Elsevier Ltd. All rights reserved.
2. impact on oral health-related quality of
life.4
The facial profile comprises five
main prominences: the forehead, nose,
lips, chin, and the submental–cervical re-
gion.5
Additionally, lip thickness, lip to-
nicity, initial incisor inclination, and lip
height affect the resulting soft tissue
changes and consequently the aesthetic
outcome.6
The final aesthetic outcome,
however, is determined by the procedure
performed, individual soft tissue adapta-
tion, and achievable possible tendency.7,8
The lip and the chin are the two regions
influenced by mandibular setback and
maxillary advancement.
Historically, Class III malocclusions
were treated by isolated mandibular set-
back; however, bimaxillary procedures
have become increasingly frequent.9–12
One important reason for the increase in
bimaxillary procedures is the achievement
of stable long-term results.2,3
However,
one-jaw surgery is often sufficient to cor-
rect most of the dentofacial deformity, and
two-jaw surgery can increase the risk of
complications. The selection of which jaw
to operate on is generally based on the
position of the maxilla and the mandible.
Mandibular setback is generally the pro-
cedure of choice if the mandible is posi-
tioned anteriorly with the maxilla in the
normal position.13
Many studies have compared the aes-
thetic outcomes of mandibular setback
surgery, maxillary advancement surgery,
and combined surgery.9–13
In this study,
the aesthetic outcomes of mandibular
setback surgery were compared to those
of maxillary advancement surgery in
patients suffering from class III dento-
facial deformities with the maxilla in the
normal position. The hypothesis was that
in patients with a class III deformity
with the maxilla in the normal position,
the aesthetic outcome differs between
maxillary advancement and mandibular
setback.
Materials and methods
The study was performed in accordance
with the Declaration of Helsinki statement
for medical research involving human
subjects.16
The study protocol was
reviewed and approved by the Ethics
Committee of RWTH Aachen University
prior to study commencement. As the
patients in this study remained anony-
mous, the consent process was not com-
pulsory.
A retrospective cohort study was con-
ducted based on the clinic medical
records. The patients (n = 34) underwent
combined orthodontic and orthognathic
surgery and were assigned to either the
mandibular setback group (n = 17) or the
maxillary advancement group (n = 17)
according to the surgical procedure per-
formed. Although different orthodontists
performed the orthodontic treatment, one
surgeon performed all of the mandibular
setback procedures and another performed
all of the maxillary advancement proce-
dures. The examiner in this study was
blinded to the surgeon names. The study
inclusion criteria were as follows: (1) non-
syndromic patient with a class III dento-
facial deformity and a preoperative sella–
nasion–A-point angle (SNA) of 80–848
and Wits value of <0 (the Wits value is
the distance between AO (perpendicular
from A-point to occlusal plane) and BO
(perpendicular from B-point to occlusal
plane))16
; (2) the patient had completed
skeletal growth; (3) the surgical treatment
performed was either mandibular setback
or maxillary advancement; (4) the patient
had not undergone previous surgery in-
volving the middle or lower face.
A lateral cephalogram was taken at the
beginning of orthodontic treatment (T1)
and at least 6–10 months postoperatively
(T2), after the postoperative swelling had
subsided. Patients were asked to have their
teeth in occlusion and their lips in an
unstrained and relaxed position to avoid
muscular compensation. The changes in
outcome (pre- and postoperative) were
compared by means of continuous out-
come distances and angles (sagittal, verti-
cal), cervical length (Gn0
–H: the distance
between the soft tissue gnathion (Gn0
)
point and the neck point (H)),17,18
nose
position, and dental, upper lip, and lower
lip changes (Fig. 1).
Statistical analysis
To assess the differences between the two
groups – mandibular setback vs. maxillary
advancement – the analysis of covariance
(ANCOVA) models were adjusted to the
data of the 14 outcome parameters sepa-
rately (Table 1). Specifically, cervical
length served as a dependent variable;
age, sex, and treatment, as well as the
(two-way) interaction between age and
treatment and the (two-way) interaction
between sex and treatment served as inde-
pendent variables (fixed-effects). Normal
errors were assumed and the validity was
checked by residual and influence diag-
nostics. Similar models were used for the
other outcome variables.
Using a backward selection process, the
model was first reduced by removing
the non-important interaction terms
(P > 0.05) and was then continued in
the same way with the main effectors of
sex and age. Of primary interest was the
effect on the main effect treatment group
in the ANCOVA models. The type 1 error
rate for the multiple testing of the 14
outcome variable endpoints was con-
trolled using Hochberg’s multiple testing
procedure.19
The results of the adjusted
effects of the different treatments (adjust-
ed for age and sex and the interaction
term) on the respective outcome variables
are given in Table 2, along with the 95%
confidence intervals for the mean differ-
ence, the P-values, and the (adjusted)
Hochberg significance levels. The overall
significance level was set to 5%. All com-
putations were performed using SAS ver-
sion 9.4 (TS1M1) (SAS Institute, Cary,
NC, USA) in Windows X64 7 Pro (Micro-
soft, Redmond, WA, USA).
Results
This study included 34 patients with a class
III dentofacial deformity and an SNA of
80–848; 14 were male and 20 were female,
and they ranged in age from 16 to 51 years
(mean age 25 years). These patients under-
went combined orthodontic–surgical treat-
ment, and cephalograms were taken pre-
and postoperatively. The mean age of
the maxillary advancement group was
31 years, and the mean age of the mandib-
ular setback group was 25 years
(t = À1.86, df = 35.7, P = 0.070). The
mean mandibular setback was À7.1 mm
(maximum À12.9 mm, minimum À2 mm)
and the mean maxillary advancement was
4.6 mm (maximum 8.5 mm, minimum
2.4 mm).
The sella–nasion–B point angle (SNB),
SNA, and Wits appraisal changed signifi-
cantly depending on the procedure per-
formed (SNB: t = À6.61, df = 27.05,
P = 0.0001; SNA: t = À5.84, df = 25.97,
P = 0.001; Wits: t = À1.75, df = 25.66,
P = 0.008).
There was a significant difference be-
tween the maxillary advancement and
mandibular setback groups with regard
to sex (P = 0.003).
The cervical length differed significant-
ly depending on whether mandibular set-
back or maxillary advancement was
performed (P = 0.0003). The mean preop-
erative cervical length was 55.00 mm
(standard deviation (SD) 7.95) in the man-
dibular setback group and 54.00 mm (SD
11.49) in the maxillary advancement
group. The mean postoperative cervical
length was 46.00 mm (SD 11.28) in the
mandibular setback group and 56.00 mm
(SD 10.97) in the maxillary advancement
group.
2 Ghassemi et al.
YIJOM-3562; No of Pages 7
Please cite this article in press as: Ghassemi M, et al. Maxillary advancement versus mandibular setback in class III dentofacial
deformity: are there any differences in aesthetic outcomes?, Int J Oral Maxillofac Surg (2016), http://dx.doi.org/10.1016/
3. The mean change in the lip–chin–throat
angle was 10.478 (SD 6.5) in the mandib-
ular setback group and À0.648 (SD 9.1) in
the maxillary advancement group; the
change in the lip–chin–throat angle in
the mandibular setback group appeared
to be significantly different to that in
the maxillary advancement group
(P = 0.024), but this difference was not
significant using the Hochberg procedure.
The change in upper lip thickness in
the mandibular setback group was not
significantly different to that in the
maxillary advancement group when
using the Hochberg significance level
(P = 0.029).
The distance between the lower lip and
the aesthetic line in the mandibular set-
back group was not significantly different
to that in the maxillary advancement
group (P = 0.549).
The postoperative change in the soft
tissue facial angle in the maxillary ad-
vancement group (mean À0.888, SD
2.61) was similar to that in the mandibular
setback group (P = 0.128).
The postoperative facial contour angle
did not differ significantly between the
groups using the Hochberg significance
level (P = 0.205).
The postoperative anterior movement
of the upper lip in the mandibular setback
group (mean 0.88 mm, SD 2.75) was sim-
ilar to that in the maxillary advancement
group (mean 1.58 mm, SD 2.93)
(P = 0.549).
Maxillary advancement vs. mandibular setback 3
YIJOM-3562; No of Pages 7
Please cite this article in press as: Ghassemi M, et al. Maxillary advancement versus mandibular setback in class III dentofacial
deformity: are there any differences in aesthetic outcomes?, Int J Oral Maxillofac Surg (2016), http://dx.doi.org/10.1016/
Fig. 1. Graphic showing the mean tracing of the hard and soft tissues (gonion angle, mandible inclination, lower lip to E-line, nasolabial angle, soft
tissue facial angle, nose prominence, upper lip thickness, upper lip length, lower lip length, cervical length, lip–chin–throat angle, facial contour,
upper lip to E-line).
4. The postoperative change in the upper
incisor inclination in the mandibular set-
back group (mean 1.98, SD 7.1) was simi-
lar to that in the maxillary advancement
group (SD 8.2) (P = 0.549).
The nasolabial angle increased after
mandibular setback (SD 7.53) and de-
creased after maxillary advancement
(SD 6.5), but the difference between the
groups was not significant (P = 0.772).
There was no significant difference be-
tween the two groups in mandible inclina-
tion (P = 0.819) or length of the lower lip
(P = 0.820).
Although the nose prominence tended
to decrease more in the mandibular set-
back group (mean À0.94 mm, SD 2.4)
compared with the maxillary advancement
group (mean À1.58 mm, SD 2.9), this
difference was not significant (P = 0.820).
The postoperative change in gonion
angle of the mandibular setback group
(SD 3.6) was similar to that in the maxil-
lary advancement group (P = 0.800).
Discussion
The purpose of this study was to compare
the aesthetic outcomes of maxillary ad-
vancement with those of mandibular set-
back in patients with a class III dentofacial
deformity but with the maxilla in the
normal position (SNA of 80–848). This
should help in selecting the appropriate
jaw if one-jaw surgery is planned, or in
choosing the appropriate amount of
movement for each jaw if two-jaw surgery
is considered.
The facial appearance after maxillary
advancement was more favourable than
that after mandibular setback. It was ob-
served that the cervical length increased
after maxillary advancement in contrast to
mandibular setback. Additionally, man-
dibular setback resulted in a straightening
of the upper lip with a concomitant unde-
sirable increase in the nasolabial angle.
To reduce the selection bias, the sur-
geons were asked for their reasons for
choosing maxillary advancement or man-
dibular setback. The surgical procedure
was chosen based on personal preference
in relation to clinical findings or the posi-
tion of the jaw. Mandibular setback was
the main procedure performed before
2005, but maxillary advancement became
the main procedure thereafter.9–11,14,20
To
reduce measurement bias, all cephalo-
grams were traced and digitized by the
same examiner. The surgical approaches
applied were the one-piece Le Fort I
osteotomy for maxillary advancement
and the bilateral sagittal split osteotomy
for mandibular setback. The preoperative
cervical length was similar in the two
groups, but increased significantly after
maxillary advancement and decreased af-
ter mandibular setback.
No increase in the incidence of double
chin was observed following maxillary
advancement (Fig. 2) when compared to
mandibular setback (Fig. 3). This may
explain the more favourable facial appear-
ance in the maxillary advancement group
and its impact on the chin region. There
was considerable variation in the change
4 Ghassemi et al.
YIJOM-3562; No of Pages 7
Please cite this article in press as: Ghassemi M, et al. Maxillary advancement versus mandibular setback in class III dentofacial
deformity: are there any differences in aesthetic outcomes?, Int J Oral Maxillofac Surg (2016), http://dx.doi.org/10.1016/
Table 1. Values of selected cephalometric variables before and after surgery (mean Æ standard
deviation), with Dahlberg’s standard deviation of error for each variable.
Variables Before surgery After surgery Accidental error
SNA (8) 81 Æ 4.15 81 Æ 4.13 0.8
SNB (8) 83.9 Æ 4.71 80.5 Æ 4.21 0.79
Wits appraisal (mm) À10 Æ 4.08 À4.1 Æ 3.52 0.75
Gonion angle (8) 128.5 Æ 6.32 128.17 Æ 6.87 0.69
Mandible inclination (8) 34.61 Æ 6.83 34.76 Æ 6.44 0.78
Upper 1 inclination (8) 105.61 Æ 7.61 104.88 Æ 5.80 0.81
Lower lip to E-line (mm) À8.3 Æ 3.31 À5.7 Æ 3.71 0.51
Nasolabial angle (8) À2.5 Æ 3.24 À3.4 Æ 3.03 0.78
Soft tissue facial angle (8) 110 Æ 12.53 100.6 Æ 12.2 0.8
Upper lip thickness (mm) 18.2 Æ 3.53 16.5 Æ 3.32 0.51
Pg0
(mm) 13 Æ 3.23 13 Æ 4.23 0.7
Upper lip length (mm) 21.9 Æ 3.34 23.7 Æ 4.43 0.4
Lower lip length (mm) 46.5 Æ 7.52 48.1 Æ 6.13 0.6
Cervical length (mm) 50.6 Æ 10.04 47.9 Æ 10.42 0.72
Lip–chin–throat angle (8) 50.6 Æ 10.14 47.9 Æ 10.32 0.77
Upper lip to E-line (mm) À8.3 Æ 3.32 À5.7 Æ 3.72 0.74
SNA, sella–nasion–A-point angle; SNB, sella–nasion–B-point angle; E-line, aesthetic line; Pg0
,
soft tissue pogonion.
Table 2. Values of the soft tissue cephalometric index in relation to mandibular setback/maxillary advancement.
Source
Least square mean 95% CI for
difference P-value
Hochberg significance
level Commentsa
Mandibular
setback
Maxillary
advancement
Cervical length (mm) 44.439 54.618 À15.343 to À5.014 0.0003 0.0036 (1)b
Lip–chin–throat angle (8) 113.706 106.470 0.977 to 13.495 0.024 0.0071 (1)
Upper lip thickness (mm) 17.010 14.872 0.231 to 4.044 0.029 0.0107 (1)
Lower lip to E-line (mm) À5.784 À3.862 À3.716 to À0.128 0.036 0.0143 (1)
Soft tissue facial angle (8) 93.925 95.133 À3.043 to 0.6295 0.189 0.0179 (1)
Facial contour angle (8) À9.119 À11.174 À1.184 to 5.295 0.205 0.0214 (1)
Upper lip to E-line (mm) À6.414 À5.934 À2.098 to 1.138 0.549 0.0250 (2)
Upper 1 inclination (8) 106.348 105.122 À3.176 to 5.628 0.574 0.0286 (1)
Nasolabial angle (8) 106.585 102.075 À10.335 to 7.752 0.772 0.0321 (1)
Upper lip length (mm) 22.750 23.014 À2.141 to 1.6128 0.775 0.0357 (1)
Mandible inclination (8) 32.154 31.904 À1.964 to 2.463 0.819 0.0393 (1)
Lower lip length (mm) 44.387 43.965 À3.334 to 4.178 0.820 0.0429 (1)
Nose prominence (mm) 15.808 15.603 À1.627 to 2.038 0.820 0.0464 (1)
Gonion angle (8) 126.968 127.149 À3.681 to 3.319 0.916 0.0500 (1)
CI, confidence interval; E-line, aesthetic line; ANCOVA, analysis of covariance.
a
(1) ANCOVA model with baseline value and treatment; (2) ANCOVA model with significant sex.
b
Treatment interaction.
5. in cervical length, which was greater in
patients who had maxillary advancement,
and maxilla impaction due to the autoro-
tation of the mandible. As reported in
previous studies, a straightening of the
upper lip was also found after mandibular
setback, with a concomitant increase in
the nasolabial angle. Increasing the naso-
labial angle has a negative effect on the
aesthetic outcome.22,23
Although the nose
prominence was decreased in the maxil-
lary advancement group, this amount of
decrease was similar to that found in the
mandibular setback group (Table 2).
A consciousness and perception of the
attractiveness of different facial parame-
ters may be useful in compiling the opti-
mal treatment option.23
Generally, the
amount of sagittal discrepancy and the
position of the mandible and the maxilla
vis-a`-vis the skull base are decisive factors
for selecting the surgical procedure. If
there is a small discrepancy, one-jaw sur-
gery will generally be sufficient to correct
the deformity; in such cases, two-jaw sur-
gery will inevitably increase the risk of
complications without additional benefits.
Maxillary advancement vs. mandibular setback 5
YIJOM-3562; No of Pages 7
Please cite this article in press as: Ghassemi M, et al. Maxillary advancement versus mandibular setback in class III dentofacial
deformity: are there any differences in aesthetic outcomes?, Int J Oral Maxillofac Surg (2016), http://dx.doi.org/10.1016/
Fig. 2. Photographs of a patient who underwent maxillary advancement: (a) pre-treatment, (b) post-treatment.
Fig. 3. Photographs of a patient who underwent mandibular setback: (a) pre-treatment, (b) post-treatment.
6. Many studies have shown that mandibular
setback has a negative impact on function
and can lead to a negative aesthetic
outcome in the submental region.4,10,24
In addition, maxillary advancement
increases the width of airways and
improves the aesthetics of the nasolabial
and submental regions.6
The vertical
change was similar in the two groups
(Table 2). A minimal vertical change fol-
lowing maxillary advancement caused a
forward movement of the mandible and
increased the cervical length positively, as
also reported by Proffit et al.3
As recommended in a previous study,
surgeons performing this operation should
limit the amount of mandibular setback to
less than 5 mm and correct the remaining
distance by advancing the maxilla, irre-
spective of the SNA or SNB.15
This has a
positive aesthetic impact on the submental
region, improves the functional outcome,
and shows stable, long-term results, as
reported in other studies.9,25
Some authors
have also reported that isolated mandibu-
lar setback is less predictable and less
stable,22,26–28
and others have shown that
maxillary advancement is a more stable
component and causes larger mandible
autorotation.9,12
The nose, facial contour angle, cervical
length, and facial angle are the main
components of facial aesthetics, and
should all be considered when planning
and predicting the outcome of orthog-
nathic surgery.5,15,22
Vasudavan et al.
showed that the Le Fort I advancement
produces an elevation of the nasal tip, as
evidenced by a reduction in nasal length
and nasofrontal angle, along with an in-
crease in the nasal tip protrusion.29
In the
present study, it was found that advancing
the maxilla had a great effect on the nose
(nasolabial angle and nose prominence),
the cervical length, and the upper lip, as
reported previously.1,19,25,28,30
The dis-
tance from the upper lip to the aesthetic
line – depending on the patient’s sex – was
significantly different after maxillary ad-
vancement when compared with mandib-
ular setback. In female patients, maxillary
advancement was performed more often
than mandibular setback, whereas the op-
posite was the case for male patients. A
possible reason for this is related to the
surgeon’s consideration of the double
chin deformity which can result from
mandibular setback. This requires further
investigation.
In conclusion, maxillary advancement
achieved a significantly more favourable
outcome when considering the cervical
length in class III patients, regardless of
the maxilla position. These findings
should be considered when selecting the
appropriate jaw for osteotomy.
Funding
No funding.
Competing interests
No conflicts of interest.
Ethical approval
The Ethics Committee of the Medical
University of RWTH Aachen E approved
the study (EK 150/30).
Patient consent
Written patient consent was obtained to
publish the clinical photographs.
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Address:
Mehrangiz Ghassemi
Department of Orthodontics
RWTH Aachen University
Pauwelsstrasse 30
52074 Aachen
Germany
Tel: +49 241 8035796; Fax: +49 241 8082459
E-mail: mghassemi@ukaachen.de
Maxillary advancement vs. mandibular setback 7
YIJOM-3562; No of Pages 7
Please cite this article in press as: Ghassemi M, et al. Maxillary advancement versus mandibular setback in class III dentofacial
deformity: are there any differences in aesthetic outcomes?, Int J Oral Maxillofac Surg (2016), http://dx.doi.org/10.1016/