Differences in the Buccal Bone Marrow Distance of ≤0.8 mm in the Mandible of Patients Undergoing Sagittal Split Ramus Osteotomy among the Different Skeletal Patterns: A Retrospective Study.

Yu-Chuan Tseng,Szu-Ting Chou,Chin-Yun Pan,Shih-Wei Liang,Shih-Chieh Chen,Chun-Ming Chen

doi:10.3390/jcm10235644

Abstract

This study investigated the relationship between the thickness of the ramus and skeletal patterns using cone-beam computed tomography (CBCT) for sagittal split ramus osteotomy. Ninety participants were categorized into three skeletal patterns (Class I, Class II, and Class III). The first vertical slice (slice 0) was observed in the intact mandibular canal, and then moved forward to 40 mm (slice 21) with a 2 mm interval. The thickness of buccal bone marrow (B value) was measured. A B value of ≤0.8 mm was considered to be the major risk factor causing the occurrence of postoperative lower lip paresthesia. There were 461 sides with a B value of ≤0.8 mm. There was a significant difference in the skeletal patterns [Class III (198 sides: 15.7%) > Class I (159 sides: 12.6%) > Class II (104 sides: 8.3%)]. Class II participants had significantly larger B values (2.14 to 3.76 mm) and a lower occurrence rate (≤0.8 mm) than those of Class III participants (1.5 to 3 mm) in front of the mandibular foramen (from 6 mm to 20 mm). Class III participants had significantly shorter buccal bone marrow distance and a higher occurrence rate of B values (≤0.8 mm) than Class II.

Highlights

In addition to its aesthetic implications, facial deformity is accompanied by severe malocclusion, which in turn leads to problems such as low masticatory efficiency and pronunciation difficulties
The type of orthognathic surgery that can be used to correct both types of mandibular development forms is known as sagittal split ramus osteotomy (SSRO), and it is performed for the advancement or setback of the mandible
With respect to postoperative complications, the cortical bone thickness and bone marrow thickness of the mandibular ramus play an important role in the risks of bad split [1,2,3] and lower lip paresthesia [4,5,6]

Summary

Introduction

In addition to its aesthetic implications, facial deformity is accompanied by severe malocclusion, which in turn leads to problems such as low masticatory efficiency and pronunciation difficulties. In such cases, the orthodontic treatment combined with orthognathic surgery is necessary to correct the relationship between the jaws and improve the patient’s profile. The type of orthognathic surgery that can be used to correct both types of mandibular development forms (mandibular deficiency or protrusion) is known as sagittal split ramus osteotomy (SSRO), and it is performed for the advancement or setback of the mandible. The cortical bone thickness and bone marrow thickness of the mandibular ramus could differ between the two types of mandibular deformities. With respect to postoperative complications, the cortical bone thickness and bone marrow thickness of the mandibular ramus play an important role in the risks of bad split [1,2,3] and lower lip paresthesia [4,5,6]

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