Bone healing dynamics at buccal peri-implant sites.

BACKGROUND

It is common belief that immediate implant placement into extraction sites may act to preserve the alveolar process. The objective of this study was to evaluate healing dynamics at buccal peri-implant sites in relation to the dimensions of the alveolar ridge.

METHODS

Bilateral, critical-size, supraalveolar, peri-implant defects were created in 12 male Hound Labrador mongrel dogs following surgical horizontal cut-down of the alveolar ridge. Each jaw quadrant received three 10-mm titanium implants placed 5 mm into extraction sites of the third and fourth premolar teeth leaving 5 mm in a supraalveolar position. The mucoperiosteal flaps were advanced, adapted, and sutured for primary intention healing. Bone fluorescent markers were administered at weeks 3 and 4 postsurgery, and pre-euthanasia. Incandescent, polarized, and fluorescent light microscopies were used to assess the width of the buccal wall of the alveolar ridge and local bone remodeling over the 8-week healing interval.

RESULTS

There was a significant association between the width of the buccal alveolar ridge and extent of bone resorption evaluated by incandescent and fluorescent light microscopy. A non-linear association was observed between the buccal ridge width and resorption of the alveolar ridge. A 2-mm threshold was established to account for this non-linearity. The strength of this association was two times greater in specimens with a buccal ridge width <2 mm compared with a wider ridge (beta=1.62 vs. 0.80) observed by fluorescent light microscopy. Accordingly, mean buccal resorption was significantly greater when the ridge width was <2 mm. Fluorescent light microscopy consistently showed greater buccal resorption compared with incandescent light microscopy (P<0.05). Agreement between the examination techniques was low (concordance correlation coefficient=0.49), especially for higher values of buccal resorption.

CONCLUSION

When implants are placed into extraction sites, proximity to the buccal alveolar crest appears a major consideration. The observations herein suggest that the width of the buccal alveolar ridge should be at least 2 mm to maintain the alveolar bone level. These observations likely have general implications for implant placement using most surgical protocols.