Induction of heterotopic bone formation by demineralized dentin in rats and guinea pigs

Thirty‐two isogenic and 12 allogenic first molar toothbuds from newborn rats, and 60 allogenic rat and 114 allogenic guinea pig dentin specimens treated in different ways, were implanted in the abdominal muscles of 26 rats and 27 guinea pigs for periods ranging from 4 to 12 weeks. While the non‐vital cytoplasmic substance of whole rat toothbuds was unable to induce heterotopic bone formation, demineralized or undemineralized rat and guinea pig dentin matrix did induce osteogenesis. The results indicated that dentin implanted heterotopically in young guinea pigs might be a suitable model for further studies on the induction of heterotopic bone formation since over 70% of the allogenic demineralized dentin implants in this group gave osteogenesis. It was also found that the bone induction process is retarded and the yield of new bone is low when the dentin is implanted undemineralized. Since none of the 24 sham operations resulted in any hard tissue formation, it appears that the induction of new bone formation by demineralized dentin is a specific process and not merely an unspccific reaction to trauma.