下顎骨を反時計回りに回転させた後の骨格の安定性を3つの外科手術で比較

Comparison of the skeletal stability after mandibular counter-clockwise rotation in three surgical procedures.

抄録

前歯部開咬を伴う下顎変形症の治療は困難である。本研究では、前方開咬を伴う下顎前突症に対する最良の治療法を決定するために、下顎骨骨切り術後の骨格安定性を、口腔内垂直突出骨切り術（IVRO）、従来の矢状分割突出骨切り術（conv-SSRO）、骨固定を行わないSSRO（nonfix-SSRO）の3つの術式で評価した。骨格性の下顎前突を矯正するために下顎骨骨切り術を受けた患者を対象とした。骨格と軟組織の変化は、術前（T1）、術後3±2日（T2）、術後12±3ヵ月（T3）に撮影した側方セファログラムを用いて評価した。IVRO群9例、con-fix-SSRO群11例、non-fix-SSRO群19例の計39例が対象となった。T2-T1の下顎平面角（MPA）は、IVRO群で-2.7±2.0（p＝0.0040）、conv-SSRO群で-3.7±1.7（p＜0.0001）、nonfix-SSRO群で-2.3±0.7（p＜0.0001）であった。MPAの骨格的再発はT2-T1におけるMPAとは関係なく、conv-SSRO群で約1.3°であった。MAPの骨格的再発は、IVRO群（p=0.0402）および非固定SSRO群（p=0.0173）において、T2-T1のMPAと有意に相関した。MPAの再発が1.3°未満の場合、非固定SSRO群ではT2-T1のMPAは2.5°と算出された。T2-T1のMPAが2.5°未満の場合、非固定SSROは信頼できる結果をもたらす可能性があり、2.5°以上の場合、conv-SSROはより良い結果をもたらす可能性がある。

The treatment of mandibular deformities with an anterior open bite is challenging. In this study, skeletal stability after mandibular osteotomies was evaluated to determine the best treatment for mandibular prognathism with an anterior open bite in three procedures: intraoral vertical ramus osteotomy (IVRO), conventional sagittal split ramus osteotomy (conv-SSRO), and SSRO without bone fixation (nonfix-SSRO). Patients who underwent mandibular osteotomy to correct skeletal mandibular protrusion were included. Changes in skeletal and soft tissues were assessed using lateral cephalograms taken before (T1), 3 ± 2 days (T2), and 12 ± 3 months (T3) after surgery. Thirty-nine patients were included: nine in the IVRO group and 11 and 19 in the conv- and nonfix-SSRO groups, respectively. The mandibular plane angles (MPAs) of the T2-T1 were - 2.7 ± 2.0 (p = 0.0040), - 3.7 ± 1.7 (p < 0.0001), and - 2.3 ± 0.7 (p < 0.0001) in the IVRO, conv-SSRO, and nonfix-SSRO groups, respectively. The skeletal relapse of the MPAs was not related to the MPA at T2-T1, and it was approximately 1.3° in the conv-SSRO group. The skeletal relapse of the MAPs was significantly correlated with the MPA of T2-T1 in the IVRO (p = 0.0402) and non-fix-SSRO (p = 0.0173) groups. When the relapse of the MPAs was less than 1.3°, the MPA of T2-T1 was calculated as 2.5° in the nonfix-SSRO group. When the MPA of T2-T1 is less than 2.5°, non-fix SSRO may produce a reliable outcome, and when it is more than 2.5°, conv-SSRO may produce better outcomes.