Histological study of the effect of different hydration times of bone allograft and xenograft particles on the rate of bone formation in critical size defects in the rat calvarium.

Purpose: The aim of this study was to investigate the effect of different bone graft hydration times on bone regeneration.

Methods: Five-mm defects were created on either side of the sagittal plane in the calvaria of 40 rats. In each rat, the right and left defects were filled with allograft (Cenobone^®) and xenograft (Cerabone^®) particles, respectively, based on the grouping that was randomly assigned in the study (no hydration of bone graft, 2-minute saline hydration, 10-minute saline hydration, 30-minute saline hydration, and 2-minute blood hydration). Histological and histomorphometrical analyses were performed eight weeks after surgery. The amount of new bone formation, remaining graft, and connective tissue were analyzed using the general linear model (GLM) and Bonferroni test.

Results: There was no significant difference regarding the mean of new bone, remaining graft, and connective tissue between the xenograft samples in different hydration groups. In the allograft groups, the mean new bone formation of the no-hydration and 2-minute saline-hydrated groups was significantly lower than 30-minute saline-hydrated and blood hydrated groups (P = 0.03 and P = 0.03, respectively). Regarding the variable of the remaining graft particles, the results were almost similar.

Conclusions: The results of this study showed that, the method of bone graft hydration before it is used in treating bone lesions affects osteogenesis. Especially in the case of allograft, rehydration before usage at least for 10 min is recommended.