電腦輔助設計製作手術模板應用於植牙手術的準確性

Abstract

人工植牙是從60 年代才開始發展的新技術。它是將一鈦金屬人工牙根植入上、下顎骨，讓骨組織和植入的植體產生所謂的骨整合，之後再於癒合好的人工牙根上方置入牙科補綴物。相較於傳統的活動假牙，穩定性較好，病人的接受度也較高，因此近年來尋求植牙治療的病人也越來越多。然而植牙治療的成功與否，除了和植入的植體有無成功的達到骨整合外，也和植體植入的位置、角度及方向有關，唯有精確的將人工牙根植入術前預計的位置，才能成功的將上方的補綴物回復到理想的狀態，達到美觀及功能的要求。 許多電腦輔助植牙技術的應用，即是希望將術前計劃植體植入的位置，成功的轉移至手術過程中，確保將來補綴物製作能達到當初預期的結果。包括電腦導航式手術和電腦輔助設計手術模板的製作，都是為了達到上述目的而發展出的技術。目前市面上充斥各式各樣的商品，宣稱其產品能準確的將術前計劃轉移至手術過程，然而其精密度並未被審慎的評估，而且往往因價格昂貴而無法廣泛的應用在植牙的評估與治療。 在本實驗中，我們使用可重覆置換缺牙區塊的上顎模型，利用金屬套筒導引式的手術模板，來模擬植牙手術的進行。影像的擷取則採用錐體射線電腦斷層攝影， 並利用ImplantMax 植牙軟體系統分析。結果顯示，利用金屬套筒導引式的手術模板輔助植牙手術產生誤差來源的最主要原因是來自手術模板的穩定性，意即手術模板於術前評估時在模型上的位置和手術當中手術模板固定的位置是影響準確性最大的因素，而本實驗使用手術模板輔助植牙手術的方法，所達到的準確度和文獻上其他植牙導引系統並無明顯的差異性，而利用本實驗模型方式來評估Simplant SurgiGuide 的準確性所得結果也和本實驗使用的手術模板所達到的準確性相似。

Introduction: Dental implantation is a recently developed treatment since mid 1960s. By placing a titanium fixture into the jaw bone, a predicable union (osseointegration) between bone tissue and the implant could be achieved. There seems an increasing demand in dental implantation due to its excellent performance compared to conventional dental prostheses. However, the position of the implants has decisive effect on the final results in terms of mastication, phonation, and esthetics. In order to achieve a predicable treatment outcome, a comprehensive diagnostic work-up of the planed implant positions and then precisely transferring to the implant surgery is a paramount before surgery. Image guided navigation surgery or stereographic surgical guide by CAD-CAM technique are developed for this purpose. There are many software and hardware designed by different companies available in the market nowadays. Their convenience and preciseness had been documented in many publications. However, the precision achieved was not tested by other authorities with a standardized method. The high cost of these surgical equipments or products also made them unpopular in routine planning or performing dental implant surgery. Materials and Methods: In this study, we used a simulated dental cast model to test the precision between the planned pre-operative implant position and the actual placed implant position using metal tube guided surgical templates. The radiographic examination and analysis of the implant position were performed with cone-beam CT (i-CAT) and ImplantMax software respectively. Results: The results shown that through high image resolution and precise reference markers, the positions of the implant could be predictably reported repeatedly. The pre-operative implant positions can be precisely transferred with metal tube guided surgical template. The major influencing factor in causing transfer error was the stability of the surgical guide used. That is to say, in performing dental implantation using techniques in this study, the main error was from the repeatability of the position of the surgical guide placed on the model during pre-operative planning and the position placed during surgery. The mean translation deviation were 0.3 and 0.4mm and mean angle deviation were 2.9 and 4.8 degrees in bilateral and unilateral tooth supported surgical guides respectively, which were similar to other systems reported. The mean translation and angle deviation were 0.45 mm and 3.54 degree with Simplant SurgiGuide using our study design. Conclusion: The preoperative planning of implant position could be predictably transferred to the operative field using metal tube guided surgical template. The main source of the error would be caused by the stability of the surgical guide. Using the techniques described in our study, the implant could be placed as accurately as other commercialized products like SimPlant SurgiGuide.