The soft tissue immunologic response to hydroxyapatite-coated transmucosal implant surfaces: a study in humans

OBJECTIVE: To evaluate the soft tissue response in humans immunologically and histologically after placement of mini-implants coated with or without nano-size hydroxyapatite coatings. MATERIAL AND METHODS: Commercially pure (cp) titanium mini-implants (n = 13) or nano-hydroxyapatite-coated ones (n = 12) were randomly placed into partially edentulous jaws. Crevicular fluid was sampled 1 week after placement and subjected to quantitative polymerase chain reaction analysis to explore the inflammatory markers. After 8 weeks, implants and surrounding soft and hard tissue were trephined, and undecalcified ground sections were prepared. Inflammatory cell accumulation within a defined region of interest in the soft tissue was quantified histomorphometrically. RESULTS: No statistically significant differences in immunological response to the different implant surfaces were found for IL-6 (p = .438), TGF-β2 (p = .467), MMP-8 (p = .758), CCL-3 (p = .758), IL-8 (p = .771), and IL-1β (0.771). Histomorphometric evaluation presented no statistically significant difference between the two mini-implant surfaces with regards to number of inflammatory cells (p = .669). CONCLUSION: Nano-hydroxyapatite-coated surfaces in the transmucosal region yielded similar inflammatory response and is suggested to be as biocompatible as commercially pure titanium surfaces