Effect of multiple reuse of commonly used implant analogs on the changes in the distance between internal threads: An in vitro study.

Aim: To assess the effect of multiple reuse of implant analogs of three different materials (SS, Ti, Al) on the changes in the distance between internal threads of implant analog by using two die materials at different time intervals (0, 3rd, 6th, 9th, and 12th). Settings and Design: An in vitro study. Materials and Methodology: Three commonly used implant analog materials (stainless steel, titanium, and aluminum) and two Type- IV die stone materials (Kalrock and Zhermack Elite) were used to make the samples. A total of sixty implant analogs (20 each), sixty corresponding abutments (20 each) and 720 screws (240 each) were taken, which includes stainless steel, titanium, and aluminum manufactured by Adin, Genesis, and Equinox/Myriad plus, respectively. In addition, silicone (light body consistency) was used to make an impression for the internal thread of implant analogs. The obtained samples were tested for changes in the internal threads of implant analogs while reusing the implant analogs at the interval of times (0, 3rd, 6th, 9th, and 12th) using a stereomicroscope at ×50. Here, the measured values at "0" interval were considered the control group. Statistical Analysis Used: The values obtained were statistically analyzed using One way ANOVA, independent t test, and dependent t test for multiple comparisons. Results: Based on the results obtained, the overall comparison of the mean distance between threads 1-2, 3-4, and 5-6 on the replica of internal threads of the stainless steel, titanium, and aluminum implant analog materials at 1-2 has more decrease in distance from 0 to 12th intervals, at 3-4 has less amount of decrease in distance than thread distance at 1-2 from 0 to 12th intervals, and at 5-6 has very less decrease in distance than thread distance at 1-2 and 3-4 from 0 to 12th intervals. On order the mean distance reduction between threads is more at 1-2, followed to that less reduction at 3-4 and very less reduction at 5-6. This infers that the amount of increase in the distance between the internal threads of implant analog at 1-2 has more followed by 3-4 and 5-6, respectively. Conclusion: From the study, the following inferences are drawn: That the aluminum implant analog internal threads have more amount of increase in the distance between threads followed by stainless steel and titanium. Hence, among the three materials, titanium implant analogs were most efficient for reuse.

Comparison of the effect of monolithic and layered zirconia on natural teeth wear: An in vitro study.

AIM: The aim of this study is to compare wear of the natural teeth against monolithic zirconia and layered zirconia with different surface finishing procedures such as unpolished unglazed, polished unglazed, and polished glazed. MATERIALS AND METHODS: The two-bodied wear test was carried out in a custom-made oral wear simulator with a sample size of 60 zirconia specimen opposing natural teeth. Zirconia specimen was divided into two groups layered and monolithic which further subdivided into unpolished unglazed, polished unglazed, and polished glazed groups (n = 10). The amount of enamel wear occurred for 250,000 cycles when opposed by monolithic and layered zirconia with different surface finishing methods was measured by loss of height of each tooth using three-dimensional scanning and loss of weight using sensitive balance at specified time intervals of 50,000 cycles during masticatory test considering baseline measurement as control. The data were statistically analyzed to compare the enamel wear against layered and monolithic zirconia with different surface finishing protocols by repeated ANOVA test. RESULTS: Monolithic polished unglazed zirconia showed least tooth wear followed by monolithic polished glazed zirconia, monolithic unpolished unglazed zirconia, and layered unpolished unglazed zirconia showed highest tooth wear in terms of both height loss and weight loss (P < 0.01). CONCLUSION: Within the limitations of the study, monolithic polished unglazed zirconia is wear-friendly to the opposing natural teeth, and polished surfaces in both the groups showed less tooth wear compared to the glazed surface of zirconia specimen.