Purpose To estimate the effects of the thermal cycling (TC) process on the metal surfaces of Locators, as well as retention loss, and the correlation between them. Materials and methods Twenty‐five new Locator R‐Tx were included in the study. Four areas were marked on each Locators’ patrix metal surface and scanned using a confocal scanner (μsurf explorer; NanoFocus). Three surface roughness parameters were measured in the scans: Sa (average distance of peaks from the central plain of the area), Vmp (volume of the peaks in the area), and Spc (mean curvature of the peaks describing the degree of their sharpness). Retention test was performed using Instron® 4500 compression tension tensile tester at a speed of 10 mm/min. The retention tests were done using a working model made of two acrylic blocks in which the Locator system parts were inserted. The surface parameters measurements and the retention tests were performed 2 times, once before and once after TC. The Locators were subjected to 15,000 TC cycles by investing them into 2 tubs with different water temperatures, 55°C and 5°C. During each 60‐second cycle, the Locators were submerged in each tub for 20 seconds, with a 10 second transition time between the tubs. The post‐TC retention and surface parameters measurements were compared with those prior to TC and the prior to TC measurements served as controls. Changes in parameters before and after TC were analyzed by a two‐way ANOVA nested model with random intercept and slope by restricted maximum likelihood method. Correlation between retention and surface parameters was quantified and examined using Kendall's correlation test. The findings were considered statistically significant if p < 0.05. Results There was a significant decrease in retention of 16.6N at the second retention test (p < 0.001). A significant statistical decrease in surface parameters were measured after TC process, Sa and Vmp (18 ×10–3 μm, p = 0.041 and 0.94 ×10–3 1/μm, p = 0.001, respectively). A significant statistical increase in Spc of 6.4 ×10–3 μm3/μm2 (p = 0.023) was noticed. The correlation between retention decreases and surface changes was not statistically significant. Conclusion The TC process causes a substantial reduction in retention to the Locator system over time. In addition, TC causes significant but minor changes to the Locator surface area. Most of the changes are in the horizontal dimension.

Aim: We assess the accuracy of torque controllers after several aging processes and the bacterial leakage on Implant-Abutment complexes (IAC).Methods: A total of 12 spring-type and 12 friction-type torque controllers and 48 IAC (24 conical and 24 hexagonal connections) were evaluated. Chemical, mechanical, temperature, and pressure-aging methods were applied individually to replicate clinical use. Torque controller accuracy was analyzed before and after aging using a calibrated gauge. To assess bacterial leakage, the IAC were suspended in a bacterial medium for 24 h. Direct Contact Test (DCT) and Polymerase Chain Reaction Test (RT-PCR) analyzed the infiltration of F. nucleatum and P. gingivalis into the IAC micro-gap. Results: A significant decrease in torque after 10 days of aging was found. The spring-type torque controller was affected the most, regardless of the aging method (P < 0.05). PCR results indicated that all groups exhibited significantly more bacterial leakage, regardless of the method used (P < 0.05). The conical IAC demonstrated more bacterial leakage of P. gingivalis compared with the hexagonal IAC (P = 0.07). DCT found bacterial growth in the IAC only before aging and was not identified after aging. Conclusion: Aging affects torque accuracy. A reduction in force was noticed after 10 days. The conical IAC exhibits more bacterial leakage, although this was not statistically significant.