Int J Oral Maxillofac Implants. 2021 Jul-Aug;36(4):723-729. doi: 10.11607/jomi.8647.
To assess the impact of abutment angulation on loosening torque, torque loss, and percentage of torque loss in the prosthesis and abutment screws after aging of the implant-supported prosthesis.
Fifty epoxy maxillary casts with missing central, lateral, and canine teeth were used, and each cast received two implants. All casts were divided into five groups (n = 10): (1) both implants received straight abutments (0-0); (2) the central implant received a straight abutment and the canine implant received a 17.5-degree angled abutment (0-17.5); (3) the central implant received a straight abutment and the canine implant received a 35-degree angled abutment (0-35); (4) both implants received 17.5-degree angled abutments (17.5-17.5); and (5) both implants received 35-degree angled abutments (35-35). For each cast, a three-unit zirconia restoration was fabricated, and a torque meter was utilized to tighten the abutment screw (25 Ncm) and prosthesis screw (18 Ncm). The reverse torque value was recorded for each screw. All restorations were subjected to 3,500 thermal cycles between 5°C and 55°C and load cycled for 150,000 cycles with 50-N load. After the loosening torque was measured for each screw, the torque loss and percentage of torque loss were calculated.
There was a statistically significant difference in the torque loss of the central prosthesis screw (P < .001) and canine prosthesis screw (P < .001) between study groups. The 35-35 group showed the highest percentage of torque loss, while the 0-0 group showed the lowest value. A significant difference was found regarding the torque loss of the central abutment screw (P < .001) and canine abutment screw (P < .001). The abutment screws of the 35-35 group showed the highest percentage of torque loss, while the 0-0 groups showed the lowest percentage of torque loss.
Screw loosening of the prosthesis and abutment screws increases with increasing abutment angulation after aging. In the same fixed prosthesis, the torque loss in the prosthesis and abutment screws was higher in canine screws employing different angled abutments.
评估种植体支持修复体老化后基台角度对松动扭矩、扭矩损失和基台螺丝及修复体螺丝扭矩损失百分比的影响。
使用 50 个上颌缺失中切牙、侧切牙和尖牙的环氧模型，每个模型植入 2 个种植体。所有模型分为 5 组（n=10）：（1） 两个基台均为直基台（0-0）；（2） 中央种植体为直基台，尖牙种植体为 17.5 度角基台（0-17.5）；（3） 中央种植体为直基台，尖牙种植体为 35 度角基台（0-35）；（4） 两个基台均为 17.5 度角基台（17.5-17.5）；（5） 两个基台均为 35 度角基台（35-35）。每个模型制作了一个三单位氧化锆修复体，使用扭矩计拧紧基台螺丝（25 Ncm）和修复体螺丝（18 Ncm）。记录每个螺丝的反向扭矩值。所有修复体在 5°C 和 55°C 之间进行 3500 次热循环，并进行 150,000 次 50-N 循环加载。测量每个螺丝的松动扭矩后，计算扭矩损失和扭矩损失百分比。
研究组间中央修复体螺丝（P<.001）和尖牙修复体螺丝（P<.001）的扭矩损失存在统计学差异。35-35 组的扭矩损失百分比最高，0-0 组最低。中央基台螺丝（P<.001）和尖牙基台螺丝（P<.001）的扭矩损失也存在显著差异。35-35 组的基台螺丝扭矩损失百分比最高，0-0 组最低。
种植体支持修复体老化后，基台角度越大，螺丝松动越严重。在同一固定修复体中，不同角度基台的尖牙螺丝扭矩损失和基台螺丝扭矩损失百分比较高。
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