하악상행지시상분할골절단술시 고정방법에 따른 안정성에 대한 비교연구 ; in vitro study

Abstract

I. Introduction Rigid internal fixation with miniplate and screw has been widely used in oromaxillofacial trauma and orthognatic surgery field. This method has several advantages such as higher long term stability and reduced movement of bone fragment comparing with osteosynthesis using wire fixation. But still most stable and effective fixation technique has not been estabilished yet following sagittal split ramus osteotomy. Thus most of surgeons select fixation technique depending on their experience and preference.

II. Purpose The aim of this study is to evaluate consequential resistence after loading depending on 4 differenct fixation techniques for sagittal split ramus osteotomy.

III. Material and methods 10 synthetic polyurethane hemimandible models were selected which made for simulation of sagittal split ramus osteotomy. Then hemimandibles were fixed with following 4 fixation techniques. Group A : 4 holes miniplate and 4 monocortical screws Group B : 4 holes miniplate and 4 monocortical screws with 1 additional bicortical screw Group C : 4 holes miniplate with 2 monocortical screws and 2 bicortical screws Group D : 4 holes miniplate and 4 monocortical screws with additional 2 hole plate and 2 monocortical screws at retromolar area After fixation with 4 different techniques, hemimandible models were subjected to axial loading using testing machine. The test machine was set up first at a rate of 10mm/120 seconds. Then load value and displacement were measured. Total 48 times of test were recorded and 8 failed tests were excluded with destructed models. Statistical analysis was performed with Man-Whitney U test for comparison of load value at 3mm, 7mm and 10mm displacement among 4 goups.

IV. Results Statistically significant differences were noted between group A and group C at 3 and 7 mm displacement while significant difference was not noted between group A and group B. Between group A and group D, statistically significant differences were found at all displacement point. Among any other groups, statistically significant difference was not obtained.

V. Conclusions According to mechanical tests, monocortical fixation techinique with miniplate and monocortical screw showed less resistant than other techniques. Thus oral and maxillofacial surgeons should consider the additional bicortical screw or miniplate application depending on clinical case to obtain higher stability.