Tooth hard tissue stimulates bone remodeling as a potential motive force during tooth eruption

Tooth eruption is an orientating action which migrates teeth coronally during life, even in bone or after occlusion contact is lost. The eruption pathway is due to bone resorption near the enamel crown and bone deposition around the cementum-covered roots. Due to their proximity to bone resorption and deposition, we hypothesize that the hard tissues enamel, dentine or cementum are important during eruption. In the present study, extracted human teeth were cut into enamel samples, enamel-dentine samples or dentine-cementum samples, and implanted into bone defects in rabbit tibia. Hematoxylin and eosin, tartrate-resistant acid phosphatase activity, tetracycline tracing and scanning electron microscopy were used to investigate bone resorption and deposition 1-8 weeks after surgery. The results showed that resorption lacunae with numerous osteoclasts were observed facing enamel and significant new bone deposition occurred near the cementum surface, compared to other hard tooth surfaces. These findings indicate that the enamel crown may stimulate bone resorption and initiate the eruption pathway, and that the cementum root may stimulate bone deposition. Bone regeneration initiated by tooth hard tissues may be a potential motive force during tooth eruption.