The Direction Of Distal Segment Relapses After
Mandibular Setback Surgery
Vertical Ramus Versus Bilateral Sagittal Split
Osteotomies
Ra'ed Mohammed Ayoub Al-Delayme
Yarmuk University College, Dentistry Dept
Qutabah Abdul Razak
Yarmuk University College, Dentistry Dept
Hassan Ali Hamzah
Babylon University, College of Dentistry .
Abstract
The present study evaluates the direction of postoperative horizontal and vertical changes (relapse) that
occur at B point and pogonion after vertical ramus osteotomy (VRO) without fixation and bilateral sagital
split osteotomy (BSSO) with semirigid internal fixation in mandibular setback operation in eleven patients
with mandibular setback operation B.S.SO (n=6), V.R.O(n=5) .
Postoperative changes (relapse) of B-point and Pogonion in horizontal and vertical axis from 1 week post
operatively (T0) to 1 year post operatively (T2) were assessed and compared with initial direction of set
back. In all VRO cases, distal segments moved posteriorly and inferiorly immediately after the release of
MMF.As for in BSSO cases, distal segments moved anteriorly and supereriorly immediately after the
release of MMF
Keywords
Relapse, B point, pogonion .Vertical ramus osteotomy (VRO), bilateral sagital split
osteotomy (BSSO).
‫الخالصه‬
‫العنهم د اسند‬
‫إن الهدف منن ذن ا الد اس نو ذن تقنم اتجنها النس ا الصه نع عند ام منها اسجنه الفني ال نف ج هنج األتجنهذ ن ااهقنج‬
‫س ن نو اسنند اج اس ام مننها الس ننس العمن د ل ننع و ال ننهادت ننند ن ا ننتعمهق م تلن ننا من الس ننس الق ننمج ل ننع و‬
‫نع‬
‫تنن ن اسنل هنج‬
‫ص ن‬.
‫اللهلن‬
‫إط نهل ذم نج منن ال نس‬
‫لند اصند ا نس مسنونه معنهس ن منن ن‬
‫ال ف ج عد إزالو التلن ا ن ن الف ن ن إمنه صنهألا الس نس ملق نمج لسنه ج الجهسن‬
‫ن‬
‫السقطننو )ن‬
‫ه نتعمهق تلن نا ن ل‬
‫السقطننو ) و‬
‫ال هادت‬
‫صهألا الس س العم د تصس ا القطعو ال ع دت هألتجها الخ فج‬
‫عد إزالو التلن ا ن ن الف ن‬
‫الع‬
‫تصس ا هألتجها اامهمج‬0
Introduction
Postoperative change in skeletal and dental position following the use of a VRO in
the treatment of mandibular horizontal excess has received much attention. Operations in
the vertical ramus, therefore, have become almost automatically considered when the
dental arch as a unit has to be moved (Bloomquist, 2004) .The finding that the pogonion
tends to move posteroinferiorly during intermaxillary fixation has been well documented
(Astrand & Ridell, 1973).This movement, later followed by the anterosuperior “relapse”
that occurs after skeletal fixation wires, does seem to stabilize the initial movement but
does not affect the long-term relapse (Tornes, 1989; Astrand & Ridell, 1973; Smith,
1985).Vertical instability of the VRO develops soon after the release of intermaxillary
fixation in many patients. This problem was initially attributed to the “condylar sag” seen
on x-ray films taken soon after surgery (Hall et al., 1975).
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Journal of Babylon University/Pure and Applied Sciences/ No.(3)/ Vol.(21): 2013
On the other hand, the stability of the sagittal osteotomy of the vertical ramus is the most
studied complication in orthognathic surgery. Since the relapse patterns differ between
mandibular advancements and setbacks, their particular causes most likely differ;
however, many of the principles in preventing relapse may be the same. This highlights
one of the major problems for surgeons attempting to decide on the techniques used to
minimize postoperative skeletal change. There are large variations in research techniques
as well as surgical approaches that exist not only between surgical centers in different
countries but also within the same country ( Bloomquist, 2004). Long term stability
following BSSO may be the most important thing to achieve. Since BSSO has been
introduced, the stability of BSSO has been analyzed in many studies (Busby et al., 2002;
Mobarak et al., 2000).
Materials and Methods
1.
2.
3.
4.
5.
6.
Eleven patients with skeletal class III malocclusion mandibular prognathism and
maxillary hypoplasia (developmental conditions have arisen during post uterine growth
through adulthood) have been chosen
Those patients attended to the service of
maxillofacial surgery in the General Assembly of Damascus Hospital and other private
Centers in Damascus city.
The equipment, instruments and material used include all the basic and special surgical
instruments in the orthognathic surgery.
A total of 11 patients were included in this study based on the following criteria:
All patients had Class III malocclusion with Mandibular prognathism of less than 7 mm.
with or without chin deviation
The patients had no genetic syndromes or other congenital deformities or trauma history.
Facial appearance was often the patient's main concern.
Mandibular setback through a BSSO, V.R.O without genioplasty and with or without Lef
I osteotomy.
Available preoperative and postoperative radiographs with a follow-up of 12 months or
longer.
No other surgery was performed.
The study consisted of six males 54.54% and five females 45.45%. Their mean age at the
time of surgery was 23 years with a range of 19 to 27 years. All the cases underwent
mandibular setback as follows:
Six cases B.S.S.O (intraorally); five V.R.O (three intraorally and two extraorally); seven
cases underwent Bimax (four B.S.S.O; three V.R.O); four cases isolated. All operations
were performed by different team of surgeons with the same supervisors (the investigator
was a surgeon in seven cases and assistance in four cases) as shown in Table (1),
1077
Patient
N0.
Age
(yr)
Gender
Approach
Single or double jaws
1
2
3
4
5
6
26
27
23
19
21
19
M
M
F
F
M
F
Intraorally
Extra orally
Intraorally
Intraorally
Extraorally
Intraorally
Isolated
Bimax
Bimax
Bimax
Isolated
Bimax
7
22
F
Intraorally
Isolated
8
27
M
Intraorally
Isolated
9
10
25
21
M
M
Intraorally
Intraorally
Bimax
Bimax
11
23
F
Intraorally
Bimax
Mean
23
M%=54.54
F%=45.45
Table -1-: Patient no., age (yr), gender, approach, single or double jaws
The mean over jet for all patient (3.8), the mean over jet for V.R.O (3.3) ±SD=1.44 the
mean over jet for B.S.S.O (4.5) ± SD=1.83 Tables (2) and (3) The mean open bite for all
patient (1.27), the mean open bite for V.R.O (1.2) ± SD= 0.72 the mean open bite for
B.S.S.O (1.33) ± SD=0.75 as shown in Table (2), (4)
Table -2-: Degree of over jet and over bit for each patient
Patient
No.
Degree of over jet (mm)
Degree of open Bite (mm)
1
2
3
4
5
6
7
8
9
10
11
-2.5
-3
-1.5
-4.5
-5
-6.5
-3
-1.5
-5
-4
-5.5
1.0
1.0
0.5
1.5
2
2.5
1.0
0.5
1.5
1.0
1.5
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Journal of Babylon University/Pure and Applied Sciences/ No.(3)/ Vol.(21): 2013
Operation
N
O.B
(mm)
V.R.O
5
1.2
0.72
B.S.S.O
6
1.33
0.75
Mean
±SD
S.E
C.V%
Min.
Max.
0.32
0.60
0.5
2.0
0.30
0.56
0.5
2.5
3.81
1.27
Table -3-: Degree of over jet (mm),±SD,
Operation
N
O.J
(mm)
±SD
S.E
C.V%
Min.
Max.
V.R.O
5
3.3
1.44
0.64
0.43
2.5
5.0
B.S.S.O
6
4.5
1.83
o.75
0.40
1.5
6.5
Table -4-: Degree of over bit (mm),±SD
All the basic dental model analysis with presurgical orthodontic and post surgical
orthodontic treatment has been offered for the patients treated by the same orthodontist
(the mean of presurgical orthodontic treatment is 17.29 month and the mean of post
surgical orthodontic treatments is 6.27 month)
The Radiographic and imaging analysis includes full-mouth periapical radiographic, the
panoramic radiographic, computed tomographies, 3-D computed tomography
Surgical treatments
1-BSSO in the standard fashion (Dal Pont) with semi rigid fixation (2.0 mm manipulating
systems) was accomplished with titanium manipulate at the anterior mandibular ramus.
2-VRO was performed without using any fixation systems
3- The Le Fort I was stabilized in its desired position using titanium mini plates and
screws
4-Maxillomandibular fixation (MMF) was released at (6-8weeks) after surgery in both
the VRO and BSSO groups.
1079
5- Elastic tractions used until at least 3 months after surgery to functionally control the
Operation
H.B-Point
H.pogonion
V.B-Point
V.pogonion
V.R.O.
5.04 ± 1.10
5.66 ±1.2
1.4± 0.41
1.06± ,29
B.S.S.O
5.33 ±1.24
5.88 ±1.19
1.25±0.41
0.95±0.33
postsurgical mandibular positions.
All the cases underwent horizontal setback and vertical downward movement at B-point
and pogonion as shown in table (5).
Table -5-: the degrees of surgical movement
Cephalometric analysis
The radiographic material for this study consisted of posteroanterior (PA) and lateral
cephalometric (LC) radiographs for each patient. The PA and LC radiographs were taken
as follows:
(T0) 1 week postoperatively.
(T1) 1 month postoperatively.
(T2) 1 year postoperatively.
The radiographs were taken with the same equipment and analyzed by one
investigator.
Subject assessments
Cephalograms were taken atT0 and T1, with MMF and occlusal splints in place. At
T2, cephalograms were taken in centric occlusion with released elastics and without
occlusal splints in place
Result
The movement of distal segments was assessed in the following axis and following
points:
1- Horizontal change of the B-point.
2- Vertical change of the B point.
3- Horizontal change of the pogonion.
4- Vertical change of the pogonion.
Postoperative changes (relapse) of B-point (X, Y)
Postoperative changes (relapse) of B-point from 1 week post operatively (T0) to 1 year
post operatively (T2) were assessed. The Postoperative changes (relapse) of B-point in
the V.R.O and B.S.S.O are shown in the Table (6). For X, positive values indicate
anterior movement; negative values indicate posterior movement. For Y, positive values
indicate superior movement; negative values indicate inferior movement.
Table -6-: Patient No. , Operation, T0-T1 (mm) X, T0-T1 (mm) Y, T0-T2 (mm) X, T0T2 (mm) Y
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Journal of Babylon University/Pure and Applied Sciences/ No.(3)/ Vol.(21): 2013
Postoperative changes (relapse) of Pogonion (X, Y)
Postoperative changes (relapse) of Pogonion from 1 week post operatively (T0) to 1
year post operatively (T2) were assessed.
The Postoperative changes (relapse) of
pogonion in the V.R.O and B.S.S.O are shown in Table (7). For X, positive values
indicate anterior movement; negative values indicate posterior movement. For Y, positive
values indicate superior movement; negative values indicate inferior movement.
Table -7-: Patient No. , Operation, T0-T1 (mm) X, T0-T1 (mm) Y, T0-T2 (mm) X, T0Patient
No.
Operation
T0-T1
(mm)X
T0-T1
(mm) Y
To-T2
(mm) X
T0-T2
(mm)Y
1
V.R.O.
-0.5
-0.3
-1.5
-0.5
2
V.R.O.
-1.5
-0.5
-2.5
-0.8
3
V.R.O.
-1.0
-0.3
-2.0
-0.6
4
V.R.O.
-1.5
-0.6
-2.5
-1.0
5
V.R.O.
-1.5
-0.4
-3.0
-0.7
6
B.S.S.O.
+2.0
+0.5
+3.0
+1.0
7
B.S.S.O.
+1.5
+0.5
+2.5
+0.7
8
B.S.S.O.
+0.5
+0.3
+1.5
+0.5
9
B.S.S.O.
+1.0
+0.3
+2.0
+0.5
10
B.S.S.O.
+1.5
+0.2
+2 .5
+0.3
T2 (mm) Y
Patient No.
Operation
T0-T1
(mm)X
T0-T1 (mm)
Y
T0-T2 (mm)
X
T0-T2
(mm)Y
1
2
3
4
5
6
7
8
9
10
11
V.R.O.
V.R.O.
V.R.O.
V.R.O.
V.R.O.
B.S.S.O.
B.S.S.O.
B.S.S.O.
B.S.S.O.
B.S.S.O.
B.S.S.O.
-0.5
-1.0
-0.5
-1.0
-1.0
+0.1
+0.5
+0.5
+1.0
+1.0
+1.0
-0.5
-0.5
-0.5
-0.7
-0.6
+1.0
+0.5
+0.3
+0.5
+0.2
+0.5
-1.0
-1.5
-1,0
-1.5
-2.0
+1.5
+1.0
+1.0
+1.5
+2.0
+2.0
-0.7
-1.0
-0.7
-1.3
-1.0
+1.4
+1.0
+0.6
+1.0
+0.5
+0.8
1081
11
B.S.S.O.
+1.5
+0.3
+3.0
+0.6
The comparison between V.R.O. and B.S.S.O movement
Table (8) showed the comparison between V.R.O. and B.S.S.O movement at B-pointa
and pogonion in horizontal and vertical axis.
Table -8-: The comparison between V.R.O. and B.S.S.O movement
Operation
Point
Axis
Per. Of Rel.%
Direction
V.R.O.
B.
X
27.77%
Posteriorly
V.R.O.
.B.
Y
57.14%
Inferiorly
V.R.O
Pog.
X
40.63%
Posteriorly
V.R.O
Pog.
Y
67.92%
Inferiorly
B.S.S.O.
B.
X
28.14%
Anteriorly
B.S.S.O.
B.
Y
70.40%
Superiorly
B.S.S.O.
Pog.
X
40.98%
Anteriorly
B.S.S.O.
Pog.
Y
63.15%
Superiorly
Discussion
Relapse is an important issue of concern following orthognathic surgery, especially,
operations for mandibular setback. (Kaban, 1997 ; Hogevold, 2001 ; Motamed, 1996;
1997; 1998; Yazdani etal., 2010, Chen etal., 2008; Yoshioka., 2008; Mortazavi, 2007).
Mandibular prognathic patients often have an anterior open bite. Therefore, surgery may
involve changes to close the anterior bite and open the posterior bite and this may cause
the increase of posterior vertical height and induce muscle lengthening in the vertical
direction (Kim, 2009).
Postoperative change in skeletal and dental position following the use of a VRO in the
treatment of mandibular horizontal excess has received much attention. Goldstein was the
first to use serial cephalograms to evaluate the postoperative change of the mandible after
surgical correction of the mandibular prognathism(Goldstein, 1974).However, the relapse
of mandibular surgery has been analyzed mainly by horizontal measurements. However,
relapse needs to be classified into horizontal and vertical types to evaluate its patterns and
causes (De Villa, 2005).
Direction of movement in VRO group
In all VRO cases, distal segments moved posteriorly and inferiorly immediately after
the release of MMF.
Many authors noted that The movement occurring in anterosuperior “relapse” that
occurs after skeletal fixation wires, does seem to stabilize the initial movement but does
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Journal of Babylon University/Pure and Applied Sciences/ No.(3)/ Vol.(21): 2013
not affect the long-term relapse(Tornes, 1989; Astrand & Ridell, 1973; Smith, 1985) .
Clockwise rotation and posterior movement of the distal segments are likely to have been
caused by condylar sag and muscular pull (Yoshioka et al., 2008).At 1 month post
surgery, posteriorly and inferiorly movement of the distal segment occurred, and
eventually there was minimal relapse at 1 year after surgery in the IVRO group. his is in
agreement with Yoshioka et al (Yoshioka et al., 2008).
But in Yoshioka et al. the study of anterior and superior repositioning was registered at
1 month post surgery. He mentioned that the postsurgical anterior movement of the distal
segments might have been caused by the adjustment mechanism of the condyle-fossa
relationship as a correction for condyles that were anteriorly positioned at surgery.
Another reason for anterior movement is probably repositioning of the mandible by
muscular pull as function resumes (Yoshioka et al., 2008).These movements are not
registered in my study In my study of the VRO group, the distal segment moved
significantly more posteriorly and inferiorly until 3 months after surgery, compared with
the BSSO group.
Direction of movement in BSSO group
In the BSSO group, the distal segment tended to move anteriorly after MMF removal
and was stable by postoperative 3 months. However, these changes were very small (less
than 1.5 mm) in the horizontal direction at B-point and pogonion point and similar to
previous studies (Harada etal ., 1997; Proffit etal., 1991, De Villa et al., 2005). In all
BSSO cases, distal segments moved anteriorly and supereriorly immediately after the
release of MMF (Choi et al., 2005) . Huang CS mentioned that the general direction of
this postsurgical movement was forward and slightly upward. This could be a result of
both a re-adaptation toward its original position made possible by the nonrigid fixation
and bone resorption or remodeling. (Huang eta., "in press").
Instead of the muscle pulling the bone forward, the bone yields and remodels itself to
adapt to the muscular force.
As mentioned before, there are various speculations on why relapse occurs after
BSSO for mandibular setback. And I agree with Komori et al. (Komori etal., 1989) and
De Villa et al. ( De Villa et al., 2005) who mentioned that the reasons could be
multifactorial, and that in long-term studies the cephalometric measurements reflecting
true surgical relapse could be obscured by factors such as remodeling, mandibular
growth, and differences in the time of follow-up.
Although the subjects in this study were treated by the same surgeon and orthodontist,
I agree with other authors. (Sorokolit & Nanda, 1990; Schatz & Tsimas, 1995, De Villa et
al., 2005) .That the surgical procedure and follow-up treatment itself can vary
significantly among patients and among clinicians.
In 1 report, one fourth of the patients received BSSO with wire osteosynthesis and
maxillomandibular fixation and nearly half of the patients received BSSO with rigid
internal fixation via bone screws. The mandible relapsed forward more than 4 mm as
measured at the chin. (Proffit etal., 1991) .
Mobarak et al. ( Mobarak etal., 2000) however, indicated that BSSO with rigid
fixation for mandibular setback is a fairly stable clinical procedure overall. Three years
after surgery, mean relapse at pogonion representing 26% of the surgical setback (19% at
1083
point B).
Most of the relapse (72%) took place during the first 6 months after surgery
(Kwon etal., 2000).
Conclusions
All VRO cases, distal segments moved posteriorly and inferiorly immediately after the
release of MMF. While in BSSO cases, distal segments moved anteriorly and
supereriorly immediately after the release of MMF.
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