ProFile鎳鈦旋轉器械經臨床使用及消毒後之影響

Abstract

鎳鈦根管銼在使用上有減低醫師手部疲勞及克服彎曲根管的優點，但是無法克服器械斷裂的缺點。本實驗是將臨床使用後的鎳鈦根管銼做分析探討，並利用示差掃描熱量測定，靜態彎曲測試以及疲勞斷裂實驗，以瞭解鎳鈦根管銼經高壓消毒鍋、乾熱消毒鍋及卡夾式快速消毒鍋對ProFile鎳鈦根管銼做多次高溫消毒後其晶相轉變和機械性質的影響。臨床使用後的鎳鈦根管銼以斷裂比例(58.4%)較變形比例(41.6%)高，較大號數以斷裂比例較變形比例高。斷裂中以疲勞斷裂比例(58.6%)高於扭轉斷裂比例(41.4%)。示差掃描熱量測定其結果顯示經多次高溫消毒之鎳鈦根管銼其晶相轉變時之降溫熱焓降低，靜態彎曲測試則發現經多次高溫消毒之鎳鈦根管銼彈性增加且較容易產生變形甚至於容易疲勞斷裂，尤其是經多次乾熱消毒鍋消毒較高壓消毒鍋及卡夾式快速消毒鍋明顯。

A major concern with use of nickel-titanium engine-driven rotary instruments is fracture without warning. The purpose of this study was to analyze the type and frequency of defects in ProFile nickel-titanium rotary endodontic files after routine clinical use and to draw conclusions regarding the reasons for failure. The differential scanning calorimetric (DSC) studies were utilized to undergo phase transformation within rotary nickel-titanium (Ni-Ti) endodontic instruments of the as-received condition and after more heat sterilization cycles. Static Bending Test was tested on the mechanical behavior and cyclic fatigue devices were tested on fatigue resistance of rotary endodontic Ni–Ti instruments after more heat sterilization cycles. The result was nickel-titanium rotary endodontic files after routine clinical used had more percentage on fracture (58.4%) than distortion (41.6%). The large size file had more percentage on fracture than distortion. Fracture of endodontic rotary instruments could occur under two circumstances: torsional fracture and cyclic fatigue. The cyclic fatigue (58.6%) was the major type than torsional fracture (41.4%). The differential scanning calorimetric (DSC) studies exhibit the total enthalpy change decrease within rotary nickel-titanium (Ni-Ti) endodontic instruments after 11 heat sterilization cycles. The heat cycle of the hybrid Ni–Ti instruments may be effective to increase the flexibility and decrease on cyclic fatigue cycle, specially with dry heat sterilization than steam autoclave and cassette autoclave.