Effect of early exposure on the integration of dental implants in the baboon: Part 1 - Clinical findings at uncovering

There has been increased discussion on the advantages of a one- versus a tw o-stage surgical approach in the placement of dental endosseous implants. T his study evaluated the influence of early implant exposure on crestal bone height adjacent to the implant surface and Periotest values at uncovering in the baboon. Forty-eight implants (24 commercially pure titanium, 24 tita nium alloy) were placed in maxillary and mandibular posterior sites in 6 ba boons. implant exposure was evaluated weekly for 3 weeks after implant plac ement. The level of bone adjacent to the dental implants was measured at pl acement from the top of the implant collar to the crest of the bone at the mesial, distal, buccal, and lingual surfaces. The maxillary sites were meas ured again at a 6-month uncovering, while the mandibular sites were measure d at a 3-month uncovering. Periotest readings were also recorded at uncover ing. Early implant exposure was more common in the mandible, with the major ity occurring by the second week postplacement. There were no significant d ifferences in the crestal bone height changes at uncovering between the pur e titanium and alloy implants in either arch. In the maxilla, the changes i n crestal bone height were not statistically different between exposed and nonexposed implants at any aspect. In the mandible, the difference in 3-mon th changes between exposed and nonexposed implants was significant for the distal, buccal, and lingual aspects. The overall percentage of implants wit h a Periotest reading in the "good" category was greater for the nonexposed sires as compared to exposed sires. The results of this study suggest that the two-stage surgical approach results in a better clinical outcome as co mpared to the one-stage approach in the baboon model.