Ultrastructural study of calculus-enamel and calculus-root interfaces

Conclusion: Difficulty in complete calculus removal from tooth surfaces (especially from cementum or dentin) may be due in part to the intimate contact between the calculus and the tooth, due to the chemical bonding between the calculus crystals and the tooth apatite crystals and occasional fusion (i.e., epitaxial growth) of the calculus calcium phosphate crystals with the enamel, dentin or apatite crystals. This cohesive bonding results in fracture planes occurring within the calculus instead of at the calculus-tooth interface.