Hard tissue reaction to dual acid-etched titanium implants: influence of plaque accumulation. A histological study in...

The aim of this investigation was to evaluate histologically, histometrically, and histomorphometrically the influence of plaque accumulation on the peri-implant hard tissues.

Twelve fully edentulous subjects were selected for this investigation. Four to five standard titanium screw implants were placed interforaminally. Two small custom-made screw implants were incorporated in the region of the former first molar, one in each lower quadrant. One month after abutment connection, plaque control was terminated randomly at one of the custom-made implants and continued at the other implant. The custom-made implants and the surrounding tissue were harvested after different time points of plaque accumulation (7, 21, or 90 days). Thus, according to the plaque control program and implant removal time, there were six groups each with four implants for investigation. After histologic processing of the biopsies, histologic, histometric, and histomorphometric analyses were performed.

Four of the 24 implants were unavailable for analysis. One implant was mobile at abutment connection and another implant was mobile 2 weeks after abutment connection; both implants had to be removed. The bone around two implants was destroyed during the removal with the trephine bur; therefore, these two implants could not be evaluated histologically either. No differences in the histologic appearance of the peri-implant bone between the different groups could be observed. Histomorphometrically, the implant surface in contact with mineralized bone as a fraction of the implant surface (measured from the buccal to the lingual implant shoulder) varied between 59% and 73%. The implant surface in contact with mineralized bone from the first bone-to-implant contact buccally to the first bone-to-implant contact lingually varied between 80.6% and 91.5%. The values for the distance from the implant shoulder to the first bone-to-implant contact, i.e. peri-implant bone loss, varied from 1.1 to 2.2 mm. No statistically significant differences could be found between any of the evaluated variables.

This clinical investigation is the first to evaluate the hard tissue reactions to different plaque accumulation periods. Within the limits of this experiment, it can be concluded that the bone reaction toward the different plaque accumulation periods and in the different plaque control/accumulation groups were similar. It can be further concluded that the observed bone loss is rather attributed to the establishment of the biologic width than to plaque accumulation.