Effect of multiple reuse of commonly used implant analogs on the dimensional accuracy and the marginal gap between analog and abutment – An in vitro study

Statement of Problem: During the impression procedure, the implant's exact position in the oral cavity is transferred into the cast using impression post and implant analog. As the implant, analog is a lab component, it can be reused multiple times. Reuse of implant analogs may be desirable for both environmental and financial aspects. When implant analogs are reused, it is important to be assured that they are as accurate as new ones. Reusing of implant analog results in loss of precision which is the major key factor in the failure of implant prosthesis. Purpose of the Study: The purpose of the present in vitro study is to assess the effect of multiple reuse of implant analogs of three different materials (SS, Ti, Al) on the dimensional accuracy (external and internal diameter) of implant analogs and the marginal gap between analog and abutment by using two die materials at different time intervals (0, 3rd, 6th, 9th, and 12th). Materials and Methods: Three commonly used implant analog materials (stainless steel, titanium, and aluminum) and two type – IV die stone materials (Kalrock and Zhermack elite) are 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. Addition silicone (light body consistency) was used to make an impression for the internal thread of implant analogues. The obtained samples are tested for external diameter and internal diameter of implant analogues, the marginal gap between analogue and abutment while reusing the implant analogues 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 as the control group. The values obtained were statistically analyzed using the one-way ANOVA, independent t-test, and dependent t-test for multiple comparisons. Results: Based on the results obtained, there was no change in the external diameter of three materials of implant analog in both die materials. There was an increase in the internal diameter of implant analogs in which the aluminum material exhibits more increase from 0 to 12th interval, and there was an increase discrepancy in the marginal gap between implant analog and abutment in which the aluminum material has more increase from 0 to 12th interval followed by the stainless steel and titanium implant analogs in both die materials. In between the two die materials, no significant difference was observed in all three parameters. Conclusion: From the study, the following inferences are drawn: that titanium implant analogs can be used more than three times but not more than six times, stainless steel implant analogs can be used for not more than three times, and the aluminum implant analogs can be used for one time only. Hence, among the three materials, titanium implant analogs were most efficient for reuse. Clinical implications: Micromovements of the abutment screw due to discrepancy or loss of surface details of threads of implant analog leads to micro-leakage and bacterial infiltration due to marginal gap discrepancy which further causes increased inflammation at the connection level contributing to a marginal bone loss that may affect the long-term success of implant prosthesis/implant.