EFFECTS OF THE PLATELET-DERIVED GROWTH-FACTOR INSULIN-LIKE GROWTH FACTOR-I COMBINATION ON BONE REGENERATION AROUND TITANIUM DENTAL IMPLANTS - RESULTS OF A PILOT-STUDY IN BEAGLE DOGS

THE PURPOSE OF THIS STUDY WAS TO EVALUATE the early wound healing events of bone around press-fit titanium implants inserted with and without the concurrent application of a combination of platelet-derived growth factor (PDGF) and insulin-like growth factor (IGF-I). Nine months prior to implant placement all mandibular premolar teeth were extracted in 8 beagle dogs. Subsequently, 40 specially manufactured titanium implants with 2 transverse holes in the apical section were press fit into precise recipient sites in the dogs' mandibles. The dogs were sacrificed at 7 and 21 days following implant placement yielding 12 PDGF-B/IGF-I treated and 8 control (placebo gel or non-treated) implants for each observation period. Coded undecalcified sections were analyzed for: 1) percentage of implant surface in contact with new bone; 2) percentage of peri-implant space filled with new bone; and 3) percentage of implant hole filled with new bone. An analysis of variance was used to determine significant differences among the treatment groups. At 7 days, the percentage of bone fill in the peri-implant spaces and the percentage of implant surface in contact with new bone were both significantly increased in PDGF-B/IGF-I treated sites (P < 0.01 for both groups). There was < 1.5% fill of the implant holes in both treated and control sites (no significant differences). At 21 days the percentage of bone fill in the peri-implant spaces was significantly increased in the PDGF-B/IGF-I treated sites (P < 0.01). No significant differences were detected at this time in the percentage of implant hole filled with new bone nor in the percentage of implant surface in contact with new bone. However, 10 of the 12 PDGF-B/IGF-I treated implants exhibited a greater amount of new bone within the implant holes compared to the means of the placebo gel and non-treated implants. These findings suggest that the PDGF-B/IGF-I combination can stimulate bone regeneration around press-fit titanium implants. In this model the effect appears prolonged in areas where larger bone defects exist, such as in the peri-implant marrow spaces.