| 摘要: | 正顎⼿術（orthognathic surgery），是為了修正顏⾯顎⾻發育異常所導致的咬合不正所施⾏的⼿術。傳統的正顎⼿術（下顎⾻⽮狀劈開術），在顎⾻切開移動 後，對於各⾻塊間的固定，尚未發展出良好的固定材料，因此在⼿術後為了讓重 新定位的顎⾻可以癒合良好，減少不必要的⾻塊間移動，患者需要接受術後6⾄8週的上下顎間固定術。近代的正顎⼿術發展，⾃從⾻釘⾻板廣泛地應⽤於正顎⼿術中的⾻間固定，此種⽅式⼤幅地減少術後需要將上下顎⽛⿒牢固綁起來的必 要性，同時也改善患者在術後的⽣活品質。因此，我們想知道哪⼀種⾻間固定⽅ 式是最穩定也最適合⽤於下顎⾻⽮狀劈開術。回顧⽂獻，有許多學者針對下顎⾻ 前進（mandible advancement）做了許多體外實驗，但較少針對下顎⾻後退 （mandible setback）的研究，本研究的⽬的，在於經由體外的⽣物⼒學實驗，測 試三種不同的⾻釘⾻板固定模式，在下顎⾻⽮狀劈開後退的案例中，其穩定度的 ⽐較。本實驗使⽤完整的下顎⾻⼈造假⾻模型（Synbone，序號 8596，Malans, Switzerland），分成三組，每組樣本數為8個，每個模型均由同⼀位醫師施⾏下顎 ⾻⽮狀劈開術，後退量為 8mm，再以三種不同⽅式固定。第⼀組： straight miniplate, 1.0 mm thickness, with 4-hole monocortical fixation ; 第⼆組：curved miniplate, 1.25mm thickness, with 4-hole monocortical fixation ; 第三組：Inverted-L type 3 bicortical screws fixation。再分別以材料試驗機( JSV-H1000, Japan instrumentation system Co., Nara, Japan)以incisal vertical loading進⾏⼒學測試。 測量下顎前⽛區的垂直位移量分別為 1mm,3mm,5mm,10mm 時的 resistance force(N).研究結果顯⽰:在使⽤curved plate的組別,不論在1mm,3mm,5mm這三種 不同的位移量時,其強度表現都與Inverted-L type 3 bicortical screws fixation的組 別沒有顯著差異.本研究建議臨床醫師在以下顎⾻⽮狀劈開術進⾏下顎後退的術 式時,可優先考慮以curved plate(1.25mm thickness)為⾻間固定⽅式.
Background:
The bilateral sagittal split ramus osteotomy(BSSRO) is the most popular orthognathic surgical procedure for the correction of mandibular skeletal deformities. Rigid internal fixation in BSSRO can improve postoperative stability and permit early mandibular function. Many modifications of the fixation methods in BSSRO have been published, but no consensus has been reached regarding the best clinical fixation method.
Objective:
The purpose of this study was to evaluate and compare the biomechanical behavior of different internal fixation techniques in bilateral sagittal split ramus osteotomy(BSSRO) for mandibular setback.
Materials and Methods:
Synthetic polyurethane whole-mandible replicas (Synbone, Malans, Switzerland) were used in this study. The distal segment of mandible was repositioned in a 8-mm setback position. The mandible replicas were divided into three groups: Group 1: Straight miniplate with 4-hole monocortical fixation. Group 2: Curved miniplate with 4-hole monocortical fixation. Group 3: Three bicortical screws in an inverted-L pattern fixation. The vertical loads were applied on the incisal edge by the servohydraulic mechanical testing unit. The compression loads(N) at 1, 3, 5, 10mm displacement were analyzed ( p < 0.0167 ).
Results:
Straight miniplate group ( Group 1 )was significantly weaker than the other groups ( Group 2 and 3 ). There was no significant difference between curved miniplate group ( Group 2 ) and inverted L type bicortical screws group ( Group 3 ) at 1, 3, 5 mm displacement. At 10 mm displacement, there was significant difference between Group 2 and Group 3.
Conclusion:
For mandibular setback surgery, this study concluded that the fixation technique based on the curved miniplate group was significantly the same rigid as the fixation observed in the inverted L type bicortical screws group at the displacement ≤ 5mm. |
