Bahrami Maleki Hamed, Bazooband Mona, Amini Parviz
Department of Prosthodontics, School of Dentistry, Ilam University of Medical Sciences, Ilam, Iran.
General Dentist, Shiraz, Iran.
Clin Exp Dent Res. 2025 Oct;11(5):e70222. doi: 10.1002/cre2.70222.
This in vitro experimental study aimed to evaluate the effects of laboratory contamination of implant abutment screws and connection surfaces on reverse torque values (RTVs), as an indicator of screw preload loss.
Forty-five Dentis One Q implants and 45 CCM UCLA abutments were randomly assigned into three groups (n = 15 per group). Group 1 (control) involved uncontaminated abutments and screws with no restorations. Group 2 (screw contamination) used new abutments attached with screws contaminated by laboratory materials (porcelain powder, metal debris, and polishing paste). Group 3 (connection contamination) included screw-retained restorations fabricated under contaminated conditions and attached using new screws. All samples were subjected to standardized torque (250 N·cm), thermocycling (1500 cycles between 5°C and 55°C), and subsequent RTV measurement. One-way ANOVA and Tukey's post hoc tests were used for statistical analysis (α = 0.05).
Mean RTVs (SD) were 218 (0.15) N·cm (control), 181 (0.14) N·cm (screw contamination), and 207 (0.11) N·cm (connection contamination). RTVs in the screw contamination group were significantly lower than both the control (p < 0.001) and connection contamination groups (p < 0.001). The difference between the control and connection contamination groups was not statistically significant (p = 0.08).
Laboratory contamination of implant components can significantly reduce reverse torque values, particularly in cases of screw contamination, indicating an increased risk of screw loosening. Contamination control during prosthetic procedures is essential to maintaining implant stability.
本体外实验研究旨在评估种植体基台螺钉及连接面的实验室污染对反向扭矩值（RTV）的影响，以此作为螺钉预紧力损失的指标。
将45颗Dentis One Q种植体和45个CCM UCLA基台随机分为三组（每组n = 15）。第1组（对照组）使用未受污染的基台和螺钉，且无修复体。第2组（螺钉污染组）使用附着有被实验室材料（瓷粉、金属碎屑和抛光膏）污染的螺钉的新基台。第3组（连接污染组）包括在污染条件下制作并使用新螺钉附着的螺钉固位修复体。所有样本均接受标准化扭矩（250 N·cm）、热循环（5°C至55°C之间1500次循环）以及随后的RTV测量。采用单因素方差分析和Tukey事后检验进行统计分析（α = 0.05）。
平均RTV（标准差）分别为218（0.15）N·cm（对照组）、181（0.14）N·cm（螺钉污染组）和207（0.11）N·cm（连接污染组）。螺钉污染组的RTV显著低于对照组（p < 0.001）和连接污染组（p < 0.001）。对照组和连接污染组之间的差异无统计学意义（p = 0.08）。
种植体部件的实验室污染会显著降低反向扭矩值，尤其是在螺钉污染的情况下，这表明螺钉松动的风险增加。修复过程中的污染控制对于维持种植体稳定性至关重要。
