Mandibular Body Ostectomy for Correction of Mandibular

Home , Ostectomy

Oral Science International 9 (2012) 21–25

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Case report

Mandibular body ostectomy for correction of mandibular

prognathism – A technical note

∗

Yoshiyuki Mori , Takafumi Susami, Hideto Saijo, Kazumi Okubo, Natsuko Uchino, Kazuto Hoshi,

Tsuyoshi Takato

Department of Oral-Maxillofacial Surgery, Dentistry and Orthodontics, The University of Tokyo Hospital, Tokyo, Japan

a r t i c l e i n f o a b s t r a c t

Article history: The patient presented with a large mandibular body and acceptable occlusion in the molar region with

Received 4 November 2011

no lateral crossbite.

Received in revised form 5 January 2012

After presurgical orthodontic treatment, mandibular body ostectomy was performed in the missing

Accepted 11 January 2012

second premolar region. To avoid nerve injury, we considered removal of the lateral cortical plate around

the mental foramen and temporary wire ﬁxation of the detached bone segments during contralateral Keywords:

body ostectomy.

Mandibular body ostectomy

Neurosensory supply of the mental region recovered within 3 months after surgery. Three years after

Mandibular prognathism

surgery, the occlusion and periodontal health were good.

Orthognathic surgery

1. Introduction retained; (3) the posterior molar occlusion was acceptable with no

lateral crossbite; (4) the maxillary incisors were labially inclined.

Mandibular body ostectomy for correction of mandibular prog- Based on these characteristics, especially (2) and (3), we opted

nathism is often avoided due to complications such as inferior to perform mandibular body ostectomy.

alveolar nerve injury and the development of other more reli-

able surgical procedures such as mandibular sagittal split ramus 2.1. Overall surgical-orthodontic treatment

osteotomy (SSRO) [1]. However, this procedure still seems to be

most effective in some cases, especially those with a large mandibu- Presurgical orthodontic treatment to improve the labial tipping

lar body. Furthermore, several methods combining mandibular of maxillary incisors was performed using a multi-bracket appli-

body ostectomy with SSRO or vertical ramus osteotomy have been ance for 18 months after extraction of bilateral maxillary second

reported to yield good results [2]. premolars and the retained mandibular second primary molars. The

In this paper, we report a case of mandibular prognathism in space between the ﬁrst premolar and ﬁrst molar was maintained

which we successfully performed mandibular body ostectomy with until operation, and mandibular body ostectomies were performed

minimal injury to the inferior alveolar neurovascular bundle. The in this space.

indications for mandibular body ostectomy and the necessary pre- Postsurgical orthodontic treatment was initiated to move the

cautions are discussed. mandibular molars forward for space closure and to establish an

Angle Class I molar occlusion.

2. Case summary

2.2. Surgical procedures

The patient was a 16-year-old male with anterior crossbite. He

The mental foramina were located in the center of the ostectomy

presented the following characteristics (Figs. 1 and 2): (1) Skeletal

area on both sides. The amount of setback movement planned was

Class III jaw relationship caused by a large mandible. The mandibu-

4 mm on the left side and 7 mm on the right side. A mucoperiosteal

lar body was especially large; (2) mandibular second premolars

finger flap was reflected at the crest of the space to expose the

were missing congenitally and the second primary molars were

mental foramen and the inferior border of the mandible (Fig. 3A).

To avoid tension on the neurovascular bundle, a rectangular bony

∗ cut was designed around the mental foramen (Fig. 3B). Bone cuts

Corresponding author at: Department of Oral-Maxillofacial Surgery, Dentistry

(1 cm × 2 cm) were performed using a ﬁssure bur and the bone

and Orthodontics, The University of Tokyo Hospital, 7-3-1 Hongo, Bunkyo-ku, Tokyo

was removed with an osteotome. The incisal branch of the neu-

113-8655, Japan. Tel.: +81 3 5800 8669; fax: +81 3 5800 6832.

E-mail address: [email protected] (Y. Mori). rovascular bundle was ligated and severed. The main trunk of the

22 Y. Mori et al. / Oral Science International 9 (2012) 21–25

Fig. 1. Preoperative ﬁndings (16 years of age): (A) lateral cephalogram; (B) facial proﬁle and (C) facial diagram of the patient compared with the age and sex-matched

Japanese norm [12]. The mandibular body was especially large.

Table 1

neurovascular bundle was preserved. Ostectomy was performed

Hypoesthesia of the lower lip (Semmes-Weinstein monoﬁlament aesthesiometer).

with a reciprocating saw (Fig. 3C). Tension is usually produced on

Normal threshold is 1.65. Sensory response of the lower lip decreased immediately

the nerve during movement of the bone segment that has already

after surgery but returned to normal within 3 months.

been detached. Thus, to avoid nerve injury during ostectomy on

Postsurgical period Semmes-Weinstein touch test

the opposing side, holes were drilled in the bone and the bone seg-

ments were temporarily ﬁxed using a Ø0.4-mm wire (Fig. 3D). After 3 weeks 3.22

6 weeks 2.44

completion of the ostectomies, the temporary wire ﬁxation was

10 weeks 1.65

released. The anterior segment was moved posteriorly and a con-

tinuous orthodontic rectangular arch wire was applied to the lower

dental arch and intermaxillary ﬁxation was placed. Then, bone seg-

immediately after surgery but recovered to the normal value (1.65)

ments were ﬁxed with titanium miniplates bilaterally (Fig. 4). One

within 3 months (Table 1).

week after surgery, the intermaxillary ﬁxation was released and

intermaxillary elastics were used for 6 weeks.

2.4. Outcome 3 years after surgery

2.3. Sensory response of the lower lip after surgery

The miniplates were removed 1 year after surgery. Conse-

The touch detection test for mental nerve using a Semmes- quently, the orthodontic appliance was removed 2 years after

Weinstein monoﬁlament aesthesiometer [3] revealed that cuta- surgery. Three years after surgery, the patient’s proﬁle and occlu-

neous pressure threshold of the mental region had increased sion had improved (Figs. 5 and 6) and the periodontal tissues at the

Fig. 2. Occlusion before the surgical-orthodontic treatment: (A) frontal view; (B) lower dental arch and (C) panoramic radiograph. Mandibular second premolars were missing

congenitally and the second primary molars were retained. The posterior molar occlusion was acceptable with no lateral crossbite.

Y. Mori et al. / Oral Science International 9 (2012) 21–25 23

Fig. 3. Preservation of neurovascular bundle: (A) a mucoperiosteal finger flap was reflected at the crest of the space to expose the mental foramen and inferior border of

the mandible. Arrows: incision lines; (B) to avoid tension on the neurovascular bundle, rectangular bony cuts were designed around the mental foramen; (C) cortical bone

segment (1 cm × 2 cm) was removed. The incisal branch of the neurovascular bundle was ligated and severed. Main trunk of the neurovascular bundle was preserved. Arrow:

neurovascular bundle and (D) illustration of the ostectomy procedure. During osteotomy of the opposing side, the bone segments were ﬁxed temporarily using Ø0.4-mm

wire.

Fig. 4. Bone ﬁxation. Bone segments were ﬁxed with a rigid orthodontic wire and titanium miniplates. Arrows: drilled holes found as radiolucency.

24 Y. Mori et al. / Oral Science International 9 (2012) 21–25

Fig. 5. Postoperative ﬁndings (at 3 years after surgery): (A) lateral cephalogram; (B) facial proﬁle and (C) facial diagram of the patient 3 years after surgery compared with

before treatment.

ostectomy sites were healthy. On the radiograph, no root injury or alveolar neurovascular bundle during surgery, the need for postop-

resorption of the adjacent teeth was observed and radiolucency of erative periodontal management because the ostectomy site is near

the ostectomy area and drill holes on the right side had disappeared the teeth, and the need for relatively long intermaxillary ﬁxation

(Fig. 6C). There was no neurosensory disturbance of the lower lip because of the small contact area of the bone segments and the need

and incisors. for wire preparation on a prediction model before surgery since an

arch wire is attached to the mandibular dentition intraoperatively.

3. Discussion Attempts to minimize these disadvantages include widening the

contact area of the bone fragment of the ostectomy area to obtain

Mandibular body ostectomy has long been used for surgical postoperative stability, creating space to house the inferior alveolar

correction of mandibular prognathism. Blair [4] ﬁrst reported this neurovascular bundle, and creating enough room for ostectomy in

procedure in 1907. Later, many attempts to preserve the inferior presurgical orthodontic treatment [7–9]. Based on these advances

alveolar neurovascular bundle were reported [5], and a two-step in surgical procedures and considering the features of mandibular

surgery to prevent postoperative infection [6] was introduced. With deformation and occlusal relationship of the patients, we think that

the widespread use of mandibular SSRO such as the Obwegeser-Dal mandibular body ostectomy would be the most effective method

Pont method, mandibular body ostectomy has been performed less for some patients with a large mandibular body [10].

often in recent years [1]. Reasons for this include a high risk of dam- Regarding the indications for mandibular body ostectomy,

age to the teeth adjacent to the ostectomy area and to the inferior the following features are considered: (1) mandibular protrusion

Fig. 6. Occlusion after the surgical-orthodontic treatment (at 3 years after surgery): (A) frontal view; (B) lower dental arch and (C) panoramic radiograph. A good occlusion

was obtained with no periodontal injury at the ostectomy sites. Radiolucency of ostectomy area was not found.

Y. Mori et al. / Oral Science International 9 (2012) 21–25 25

and/or skeletal open bite caused by large mandibular body; (2) body ostectomy has advantages in terms of respiratory care after

congenital or acquired absence of tooth, or bad tooth condition surgery.

in the molar region; (3) the required amount of ostectomy is These results indicate that mandibular body ostectomy is still a

within a single tooth width; and (4) good posterior occlusion treatment option for orthognathic correction of mandibular prog-

[9]. nathism.

As the present patient had these features, we considered

mandibular body ostectomy as the most effective method to Acknowledgments

improve his facial proﬁle and occlusion. If we chose other meth-

ods, such as SSRO, the arch width in the molar region would have

We thank Dr Kikuya Yanase of Yanase Dental & Orthodontic

to be changed in the presurgical orthodontic treatment and dental

Clinic (Ohmiya, Japan) for performing the orthodontic treatment.

implants or bridges might be required in place of primary teeth in

the future.

References

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