不同長度之支柱螺絲於疲勞測試後扭矩變化之探討

Effects of Screw Length on Changes in Screw Removal Torque after Cyclic Loading

林剛瑋(Kang-Wei Lin)

指導教授 ： 林立德

國立臺灣大學/醫學院/臨床牙醫學研究所/碩士(2017年)

https://doi.org/10.6342/NTU201703589

摘要

研究目的：
牙科植體已廣泛應用於牙科治療中，但植體補綴物的支柱螺絲斷裂是常見的併發症之一，臨床上一旦發生支柱螺絲斷裂，要在口內將支柱螺絲取出的難度甚高。若支柱螺絲長度較短，斷裂在植體內部的部分也會較短，要將斷裂部分取出的難度也會較低。若發生支柱螺絲斷裂，臨床上另一作法是不取出斷裂部分，另取一較短長度之支柱螺絲直接鎖緊支柱。但較短長度的支柱螺絲是否能提供與完整長度支柱螺絲相同的夾緊力以維持支柱和植體間的穩定則尚不清楚。本研究目的即為藉由測量疲勞測試前後之支柱螺絲移除扭矩來比較不同長度支柱螺絲之穩定性。
材料與方法：
本研究使用IDEOSS系統之4mm直徑內接式植體及5mm直徑內接式植體。4mm直徑植體分為使用完整長度10圈螺紋支柱螺絲、較短長度8圈螺紋支柱螺絲及6圈螺紋支柱螺絲組別；5mm直徑植體分為使用完整長度10圈螺紋支柱螺絲及較短長度8圈螺紋支柱螺絲兩組。所有植體總共分為五組，每組含四個樣本。將植體以符合ISO 14801規範之方式包埋於夾具之中後，以廠商建議之扭力值由MODEL-2205NS扭力試驗儀鎖緊支柱螺絲兩次，中間間隔十分鐘，之後再以扭力測試儀測量支柱螺絲之初始移除扭矩。測得初始移除扭矩後，再次將支柱螺絲鎖緊，將特製金屬帽套上支柱，並以符合ISO 14801規範之方式於Instron E3000疲勞測試儀器進行疲勞測試。疲勞測試之頻率設定為15Hz，施力大小設定為以正弦函數方式變化之變動大小，最大施力值為219N，最小施力值為21.9N，施力之次數設定為30萬次，模擬補綴物使用一年之咬合次數。完成後，再以扭力測試儀測量疲勞測試後移除扭矩。
結果：
在初始移除扭矩方面，當使用完整長度10圈螺紋支柱螺絲時，5mm直徑植體之初始移除扭矩較4mm直徑植體大，且達顯著差異。但使用8圈螺紋支柱螺絲時便無顯著差異。在使用4mm直徑植體搭配6圈螺紋支柱螺絲組別中，四組樣本中有兩組樣本無法測得初始移除扭矩。而在疲勞測試後之移除扭矩方面，不論在4mm直徑植體或5mm直徑植體上，使用完整長度10圈螺紋支柱螺絲組別之移除扭矩和使用較短長度8圈螺紋支柱螺絲組別之移除扭矩都沒有顯著差異。
結論：
在模擬使用一年的咬合次數30萬次的疲勞測試下，不論是在4mm直徑植體或5mm直徑植體中，較短長度8圈螺紋的支柱螺絲和完整長度10圈螺紋支柱螺絲的穩定性都沒有顯著差異。

關鍵字

人工牙根 ； 支柱螺絲 ； 支柱螺絲長度 ； 疲勞測試 ； 移除扭矩

並列摘要

Purpose:
One of the major technical complications of fixed implant prosthesis is abutment screw fracture. It’s difficult to remove the fracture segment of abutment screw inside the implant body clinically. If we use a short abutment screw, it will be easier to remove the fracture segment inside the implant body once the abutment screw fractured. The relations between abutment screw length and abutment-implant joint stability has not been well studied. The purpose of this study is to evaluate the relations between abutment screw length and abutment-implant joint stability by measuring the screw initial remove torque value and post-cyclic loading remove torque value.
Material and method:
Twenty IDEOSS internal-connection implants were used. 12 were 4mm-diameter implant and 8 were 5mm-diameter implant. 4mm-diameter group was further separated into three groups: a group using full-length, 10 threads abutment screw, a group using shortened, 8 threads abutment screw and a group using 6 threads abutment screw. 5mm-diameter group was separated into two groups: a group using full-length, 10 threads abutment screw and a group using shortened, 8 threads abutment screw. The implant body were embed into aluminum jigs with epoxy resin and cement-type abutments were attached. Abutment screws were tightened twice with 10 minutes interval with suggested torque by manufactory with the MODEL-2205NS torque machine. The initial remove toque values were measured by the torque machine and were recorded then. After the initial remove torque values were recorded, abutment screws were re-tightened and custom-made metal caps were attached to the abutments. The implant assemblies were loaded with 21.9N-219N sinusoidally at a 15Hz frequency for 300,000 cycles, with corresponded to approximately 1 year of normal masticatory function. After cyclic loading, the post-loading remove torque values were measured with the torque machine and were recorded.
Results:
The initial remove torque value with 10-thread abutment screw of 5mm-diamter implant was greater than 4mm-diameter implant group. The initial remove torque value cannot be measured in two out of four samples in the 4mm-diameter implant with 6-thread abutment screw group. The post-loading remove torque values showed no significant differences between 10-thread abutment screw group and 8-thread abutment screw group in both 4mm-diameter implant and 5mm-diameter implant.
Conclusion:
Within the limitations of this study, short abutment screws provide the same abutment-implant connection stability as full-length abutment screws after cyclic loading.

並列關鍵字

dental implant ； abutment screw ； abutment screw length ； fatigue test ； remove torque value

參考文獻

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