ABSTRACT
This in vitro study aims to assess inward bacterial microleakage at the implant-healing abutment (IHA) interface in two different implant designs, namely platform switching (PS) and platform matching (PM). Five samples were collected from each of the PS and PM implant systems. In the first phase, healing abutments were tightened onto the implants by 10 Ncm torque. Next, IHA assemblies were immersed in an Escherichia coli (E. coli) suspension for 24 hours and 7 and 14 days. The healing abutments were then unscrewed, and samples were collected from the internal part of the implants and streak-cultured on culture media. After 1 day of incubation, the number of grown colonies was counted. In the second phase, the aforementioned steps were repeated for the assemblies that were torqued by 20 Ncm. Data were analyzed by the Kruskal-Wallis and Mann-Whitney tests (α = 0.05). The mean colony count was found to increase over time in the PM group torqued by 10 and 20 Ncm; however, this increase was only significant for 10 Ncm torque (P = 0.02). In the PS group, the colony count did not follow a certain pattern over time, neither in the 10 Ncm nor in the 20 Ncm torque. The mean colony count in the PS group was lower than that in the PM group at all time points in both torques. This difference was not significant at day 1, irrespective of torque value, but it was significant at 7 and 14 days, in both 10 and 20 Ncm torques (P < 0.05). Thus microleakage is lower in PS than PM design. The selection of a PM or PS design is a more important factor than the applied torque (10 or 20 Ncm) for reduction of bacterial microleakage in Tube-in-Tube implant systems with screw-retained connections.
