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directs the cut downward to give a favorable lingual split.
The surgical design also provides flexibility in placing the
anterior half of the cut downwards in favorable bicortical
region in cases of anatomical variation this avoids the
possibility of coronoid fracture.

Advantages of a GO osteotomy cut in specific situations to
prevent bad splits are as follows: (1) in regular situations
a GO cut provides flexibility in adjusting the direction
of the posterior medial cut if the anterior cut has been
placed in an unfavorable direction; (2) in cases in which
the ramal occlusal plane angle is < 70°, a parallel
[3]
osteotomy would be directed superiorly, cutting the
inferior portion of the neck of the condyloid process.
[1]
To prevent this from occurring, it is advised to place the
horizontal osteotomy cut at an altered angle of 10°-15°
inferiorly. As the suggested modification already includes
[3]
a 15° bur angulation for the anterior cut, it is not necessary
Figure 1: (a) Anterior half cut running parallel to occlusal plane (colored to adjust the osteotomy cut further; (3) in cases with a
line); (b) posterior half cut (guiding oblique (GO) cut) with an angulation of
“θ” running obliquely downwards and ending in lingual fossa; (c) favorable high lingula, there is an increased incidence of unfavorable
lingual split directed towards inferior body osteotomy by GO cut fractures. A high lingula will place the medial osteotomy
[3]
in a region of the mandibular ramus that has little or no
This completes the anterior half of the traditional medial cancellous bone. In this situation it is suggested that the
[5]
cut. The posterior half of the osteotomy cut is completed medial osteotomy be angled from its typical location in
by directing the bur obliquely downwards at an angle of the mid-ascending ramus up to the lingula of the medial
15°-20° to the anterior half of the osteotomy cut which is ramus. If cancellous bone is not encountered, the medial
[5]
parallel to occlusal plane. Care is taken to avoid damage cut is widened at the expense of cortex along the inferior
to the inferior alveolar neurovascular bundle. aspect of the medial osteotomy until cancellous bone is
seen. However, the widening creates an oblique medial
[5]
After completing the guiding oblique (GO) osteotomy cut directed upwards which increase the possibility of
cut, rest of the procedure is continued following routine bad split. This complication is successfully avoided by the
standard technique. [3]
proposed modification which allows to place the anterior
half of the cut in the favorable (bicortex) cancellous part
RESULTS of anterior ramus which is independent of the direction
of posterior cut. A similar modification can be applied in
The GO cut extends downwards 3 mm posterior to the cases of a thin mandible in which there is little cancellous
lingula from the point where the anterior half of the bone; and (4) several investigators have demonstrated
osteotomy cut was concluded. This creates an oblique an increased risk of unfavorable fractures associated
angle between anterior and posterior osteotomy cuts and with the presence of third molars at the osteotomy site
thus completes the modified medial ramus osteotomy. As during sagittal split ramus osteotomy. [5-8] The authors have
the GO cut directs the splitting forces downwards, there is observed a concentration of stress at the angle created
no possibility of the split propagating upwards to cause a by the buccal and lingual cortex of impacted third molar
coronoid or condylar fracture. during the sagittal split which may result in a lingual plate
fracture. For the same reason a lingual back cut posterior
[5]
DISCUSSION to the lingula is suggested. The addition of a lingual back
cut helps direct the lingual fracture to a more favorable split
A major disadvantage of the traditional medial osteotomy at the inferior border of the osteotomy. The present GO
[5]
cut is the effect that the anterior orientation of the bur has cut acts as a back cut when directed 3-4 mm downwards
on the direction of the posterior cut. Another shortcoming with the same angulation which directs the lingual split
of the cut is its abrupt termination at the posterior end. laterally and inferiorly to the impacted molar providing a
This produces a sharp angle at the junction of the buccal favorable split at the inferior border of the osteotomy.
and lingual cortical plates of ramus of mandible. The In conclusion, splitting the straight medial cut into two
forces applied in the sagittal split may concentrate at this components with angulation in the midpoint makes the
angle, and the stress may be propagated in any direction anterior and posterior cuts independent of each other.
to create bad splits. This is especially true in cases in Although there are many advantages and applications, a
which the posterior cut terminates in the monocortical larger study is required to compare its versatility to that
area of the medial ramus rather in the bicortical region.
of the traditional medial cut. Nonetheless, the current
In contrast to the conventional medial cut, a simple modification has proven to be successful to date in the
modification which incorporates a GO cut in its posterior author’s hands while avoiding the complications of a bad
half minimizes the stress concentrated at this angle, and split or nerve damage.

128 Plast Aesthet Res || Vol 2 || Issue 3 || May 15, 2015