Effect of early exposure on the integration of dental implants: Part 2 - Clinical findings at 6 months postloading

Implant exposure during initial healing after placement has been considered important in both implant integration and postloading effects. This study evaluated the effect of early implant exposure on the clinical findings pre restoration and 6 months postrestoration. Forty-eight implants (24 CPTi and 24 Ti- 13-13) were placed in maxillary and mandibular posterior sites in s ix baboons. Implant exposure was evaluated for 24 of the submerged implants at placement and at each weekly visit for 3 weeks after implant placement, The crestal bone level at maxillary posterior sites was measured at 6-mont h uncovering, and mandibular sites were measured at 3-month uncovering. All sites were again measured 6 months after restoration placement, Periotest readings were recorded at implant uncovering and again 6 months postloading . Arbitrary groupings of the Periotest values were assigned as good = -7 to -1; guarded = 0 to +2 and poor = +3 to +27. At 6 months postloading, there were no statistical differences between CPTi and Ti- 13-13 for change in c restal bone height in either arch. The mean change in maxillary crestal bon e height varied from a 0.59- to 1.35-mm loss. The differences between the m ean exposed and nonexposed changes were not statistically significant. The mean change in mandibular crestal bone height varied from a 0.25- to 0.88-m m loss. Changes in crestal bone height for nonexposed sites from 3-month im plant uncovering to 6 months postloading were statistically significant at the mesial, buccal, and lingual aspects. The mean change for the nonexposed distal aspect approached significance. The differences between the mean ex posed and nonexposed changes were not statistically significant. The overal l percentage of maxillary implants in the good category for nonexposed site s decreased by 41% from uncovering to 6 months after loading, while no chan ge occurred for exposed sites; the percentage of implants in the good categ ory was comparable for early exposed and nonexposed sites (57% and 59%, res pectively). At 6 months after loading, the percentage of implants in the go od category was more favorable for early exposed (88%) than nonexposed site s (50%). A one-stage implant approach should provide similar postloading cl inical results as the two-stage surgical approach.