Alveolar bone formation at dental implant dehiscence defects following guided bone regeneration and xenogeneic freeze-dried demineralized bone matrix

The present study evaluated rate and extent of alveolar bone formation in dental implant dehiscence defects following guided bone regeneration (GBR) and implantation of xenogeneic freeze-dried demineralized bone matrix (xDBM). A total of 16 titanium plasma-sprayed (TPS) and 16 hydroxyapatite-coated (HA) titanium cylinder implants were inserted in 4 mongrel dogs following extraction of the mandibular premolar teeth. Four implant sites per jaw quadrant (2 TPS and 2 HA implant sites) were prepared into extraction sockets in each dog. Buccal alveolar bone was removed to create 3 × 5 mm dehiscence defects. Two jaw quadrants in separate animals received GBR, GBR+xDBM, xDBM (control), or gingival flap surgery alone (GFS; control). Thus, four conditions were available for each implant type (TPS or HA): GBR, GBR+xDBM; xDBM and GFS. The animals received fluorescent bone labels to allow observations of rate and extent of bone formation. Animals were sacrificed at 12 weeks postsurgery and block sections were harvested for histologic analysis. There were no apparent histologic differences between TPS and HA implant defects. GBR and GBR+xDBM resulted in almost complete bone closure of the dental implant dehiscence defect. Rate of bone formation appeared higher following GBR alone. Extent of bone formation appeared somewhat greater following GBR+xDBM; however, delayed. xDBM alone did not adequately resolve the bony defect. In conclusion, GBR results in rapid, clinically relevant bone closure of dental implant dehiscence defects. Adjunctive implantation of xDBM does not appear to significantly improve the healing response in the model used.