Histomorphometric assessment of bone formation in sinus augmentation utilizing a combination of autogenous and hydroxyapatite/biphasic tricalcium phosphate graft materials: at 6 and 9 months in humans

Objective: The aim of this study was to examine the efficacy of a new biphasic hydroxyapatite/tricalcium phosphate (HA/TCP) bone substitute in combination with particulate autogenous bone in sinus floor augmentation procedures. Material and methods: A simultaneous or a two-stage sinus augmentation and implant placement were conducted in 28 patients. A mixture of HA/TCP and autogenous bone chips in a 1 : 1 ratio was used as the grafting biomaterial. Cylindrical specimen bone retrieval was performed in all patients except one. Specimens were harvested either at 6 (n=14) or 9 (n=13) months post-augmentation. For histologic and histomorphometric evaluations, the non-decalcified tissue processing (Donath's technique) was performed. Results: Newly formed bone around the grafted particles was found in all samples. The encircling, highly cellular bone followed the outline of the grafted particles in direct contact. Both woven and lamellar types of bone were observed. Morphometrically, the total mean bone area fraction of all sections was 34.8 +/- 10.3%, increasing from 28.6 +/- 7.8% at 6 months to 41.6 +/- 8.3% at 9 months (P < 0.001). Mean particle area fraction average was 25.5 +/- 11.6% and 23.5 +/- 9.3% at 6 and 9 months, respectively, with a total mean of 24.5 +/- 10.4%. The increase in bone area fraction was not significantly correlated to the decrease of the grafted particles area fraction. Conclusions: The biphasic HA/TCP showed biocompatible and osteoconductive properties. This alloplast as a composite with autogenous bone chips promotes newly formed bone, which increases in its fraction along an extended healing period.