Bone formation of demineralized human dentin block graft with different demineralization time: In vitro and in vivo study.

Objective: To evaluate structural and physicochemical characteristics of demineralized human dentin block with increasing demineralization time and to assess new bone formation when onlay grafted at different demineralization times in rat calvaria.

Study Design: Extracted human permanent teeth were pretreated and demineralized for 10-90 min. Scanning electron microscopy, X-ray diffraction analysis, inductively coupled plasma spectrometry, and energy dispersive X-ray analysis were performed. Demineralized dentin blocks (DDBs) with the representatives of the different demineralization times (10 and 60 min) were implanted in vivo onto rat calvaria (male Sprague-Dawley, n = 20 for each carrier). For controls, collagen sponge and human freeze-dried corticocancellous bone blocks (FDBB) were implanted onto calvaria (n = 20). The rats were sacrificed 2 or 8 weeks postoperatively and evaluated radiographically, histologically, and histomorphometrically.

Results: With increasing demineralization time, the surface structure of dentin blocks showed increased number and size of dentinal tubules. Moreover, the organic components increased, whereas inorganic components decreased. Crystallinity decreased sharply between 10 and 30 min demineralization time. In our in vivo study, at both time points, animals with DDBs showed significantly better bone formation than controls (p < 0.05). The DDB/60 group showed significantly increased new bone area and bone density than the DDB/10 group at 8 weeks (p < 0.05), but showed higher resorption that significantly decreased total augmented area compared with the DDB/10 group (p < 0.05).

Conclusion: DDB increased new bone formation and bone density. Further studies are needed to determine the optimal demineralization time to maximize space maintenance and bone formation of the graft material.