不同植體設計與植體穩定度相關參數於人工合成骨之探討

Abstract

實驗目的 骨整合牙科植體已成為缺牙重建治療計畫中不可或缺的一環，植體立即受力可以縮短植牙治療的時程，已成為目前研究發展的趨勢。植體的初期穩定度決定了植體適不適合立即受力的必要條件。定義上的植體穩定度為植體受力後的微移動，超過關鍵數值可能造成骨整合的失敗，但植體微移動臨床上無法直接以儀器測得。臨床上常用測定植體初期穩定度的方法如植入扭力值或共振頻率分析等方式來代表，但所測得的數值是否能夠直接代表植體的微移動量，又或者微移動的量是否因改變植體形狀，改變骨質會產生不同的結果? 因此本篇文章便想試著去探討在不同植體形狀及不同骨質情況下，植體穩定度相關參數與微移動量之間的關係。 實驗材料與方法 在此實驗中以Sawbone® test block做為均質的模擬骨塊，並選擇不同的密度（10、20pcf分別代表0.16、0.32 g/cc）來模擬不同骨密度的海綿骨，以50 pcf(0.80 g/cc)之1mm的薄層覆蓋在test block上模擬皮質骨。所使用的三種植體來自Nobel Biocare AB (Göteborg, Sweden)具有相同的表面處理但不同形狀，分別為MKIII(4.0x10mm)， MKIV(4.0x10mm) 和 NobelActive(4.3x10mm)。使用廠商建議之鑽孔規則將鑽孔擴大，並以連接至Strain Gauge Transducer Indicator(SR1 Strain Gauge Indicator，Advance Instrument Inc.，Taiwan)之扭力板手（torque wrench，Sensor Development Inc.，MI，USA），將植體慢慢的順時針帶入，直到植體完全沒入，並紀錄最高置入扭力值(peak insertion torque)和最終扭力值(final insertion torque)。 在植體上接上相對應之magnetic peg，使用Osstell® ISQ (Integration Diagnostics, Göteborg, Sweden)測量ISQ (implant stability quotient)值。再將植體接上相對應之5mm高度癒合支台，使用Periotest® (Siemens AG, Bensheim, Germany)水平進行敲擊測試，得到Periotest value。最後將植入植體之骨塊固定於微移動測量儀載具。施力裝置(Dynamic Loading Machine, Advance Instrument Inc., Taiwan）以逐漸增加之扭力平行施加於連接在植體上之5mm癒合支台頂端，及植體微移動的測量是以線性位移計[micro miniature LVDT (Linear Variable Differential Transformer), Singer Instruments & Control Ltd, Israel] 測量位於5mm癒合支台底端的植體移動量。分別記錄施力1N,2N…10N之微移動量。三種植體在相同密度之不同骨塊以隨機方式分配位置，重複測量三次。 實驗結果 (1) 在相同植體的情況下，置入扭力、ISQ會隨著皮質骨厚度增加而提升，也會受到海綿骨密度的增加而提升；Periotest value(PTV)和植體微移動量會隨著皮質骨厚度增加而降低，也會受到海綿骨密度的增加而降低，這樣的趨勢在三種不同植體都可以觀察得到。 (2) 在中等骨質(1+10pcf和20pcf)的情況下，三種植體的置入扭力皆存在有顯著差異；而MKIII及MKIV兩種植體之ISQ值可觀察到顯著差異；而三種植體之PTV皆不存在顯著差異；在植體微移動量方面，MKIII植體與其餘兩種植體(MKIV和NobelActive)存在有顯著差異，其餘兩種植體間則不存在顯著差異。 (3) 在本實驗的骨質及鑽孔規則下，三種植體的置入扭力與植體微移動量呈顯著負相關；ISQ與植體微移動量呈顯著負相關；Periotest value與植體微移動量呈顯著正相關。 結論 (1)骨質會影響植體置入扭力、ISQ、Periotest value以及植體微移動量。(2)MKIV植體在相同骨質及鑽孔規則的情況下可以獲得三種植體中(MKIII，MKIV，NobelActive)最低的植體微移動量。(3)在本實驗的骨質及鑽孔規則下，三種植體的置入扭力與植體微移動量呈負相關；ISQ與植體微移動量呈負相關；Periotest value與植體微移動量呈正相關。

Research goal The purpose of this study was to investigate the correlation between implant macrodesign with implant insertion torque, implant stability quotient, periotest value and implant micromotion in artificial bone blocks of different densities. Material and method 1. Sawbone blocks (30mm x15mm x25mm) were fabricated by combining with or without the 1mm 50 pounds per cubic foot (pcf) short fiber filled epoxy sheet on 10- or 20-pcf (density: 0.16, 0.32 g/cc) polyurethane foam test blocks, four combination blocks were used: 10pcf, 20pcf, 1+10pcf and 1+20pcf. 2. Three types of implant macrodesign (Nobel Biocare AB, Göteborg, Sweden) were used in this study: Nobelbiocare MKIII (4.0mm x 10mm; ø x length), MKIV(4.0mm x 10mm; ø x length) and NobelActive (4.3mm x 10mm; ø x length) implants. 3. Implant site preparations were performed according to manufacturer’s instruction: MK III and MK IV by step drilling with 2-mm, 2.4/2.8-mm, 3-mm drill in 10 mm depth, Counterbore drill was extra used with laminated sawbone blocks. NobelActive with final drill 3.2-mm in 10mm depth. 4. MK III, MK IV, NobelActive implants were inserted into sawbone blocks by hand torque wrench and peak insertion torque (PIT) and final insertion torque (FIT) were recorded. 5. ISQ was recorded with Osstell® ISQ (Integration Diagnostics, Göteborg, Sweden) by connecting implant with a smart peg; 6. Periotest value was recorded with Periotest® (Siemens AG, Bensheim, Germany) by connecting implant with a 5-mm healing abutment. 7. Bone block was then fixed in the vehicle, and lateral force applied to the top of 5 mm healing abutment by a Dynamic Loading Machine (Advance Instrument Inc., Taiwan), and micromotion was measured using [micro miniature LVDT (Linear Variable Differential Transformer), Singer Instruments & Control Ltd, Israel] at the opposite side of the healing abutment. Results: (1) In the same implant macrodesign, insertion torque and ISQ increased with the thickness of the cortical layer and the density of cancellous bone; on the contrast, Periotest value decreased. This trend can be observed in all three types of implant design. (2) In the medium density bone block which including 1+10pcf and 20pcf, insertion torque among three type of implant design had siganificant difference; ISQ among MKIII and MKIV implant had siginificant difference; PTV among three types of implant had no significant difference; and the micromotion between MKIII and MKIV, MKIII and NobelActive had significant difference. (3) With the bone block and the drilling protocol we used in this study, the three types of implant design had their insertion torque negatively related to micromotion; ISQ negatively related to micromotion; and Periotest value positively related to micromotion. Conclusion: (1) IT, ISQ, PTV and implant micromotion were affected by bone density. (2) Based on the same bone quality and drilling protocol, MKIV implant had the lowest implant micromotion among the three implant designs. (3) Under the bone quality and drilling protocol used in this study, IT and ISQ be negatively correlated with implant micromotion; PTV be positively correlated with implant micromotion.