Sealing Capability of Implant-Abutment Junction under Cyclic Loading: A Toluidine Blue in Vitro Study

Purpose The aim of the present in vitro study was to evaluate the leakage observed in external hexagon (EH) and cone Morse (CM) tapered implant-abutment connections, using toluidine blue. Methods A total of 60 implants, 30 with a screw-retained EH abutment and 30 with a CM taper internal connection, were used. Toluidine blue was placed into the deepest portion of the internal compartment of the 2 different implant systems, and cyclic loading was applied for each group as follows: 10 samples underwent 1 × 10 ⁶ loading cycles, 10 samples underwent 3 × 10 ⁶ cyclic loading and the least 10 samples underwent 6 × 10 ⁶ cyclic loading. Results No significant differences between the EH and CM groups were detected when the lowest loading cycles were applied (p = 0.2624), while differences were found when the samples were loaded with 3 x 10 ⁶ and 6 x 10 ⁶ cycles (p = 0.00124), with significantly lower toluidine leakage in CM group. Conclusions In conclusion, the results of the present in vitro study demonstrated that flow of the toluidine blue to the external portion of the implant-abutment assembly occurred in both types of implant-abutment connections, with very different percentages. Indeed, the CM taper internal connection seems to be more resistant to the leakage of dyes when compared with EH connections.