A review of SEM and TEM studies on the hybridisation of dentine

Hybridised dentine is a molecular-level mixture of resin polymers and demineralised dentine. Mineralised dentine does not allow monomer diffusion and therefore must be ‘conditioned’ to permit this infiltration. When dentine is prepared during clinical restorative procedures, the surface is covered by a smear layer that adheres weakly to the underlying dentine. Dentine conditioning necessitates the removal or modification of the smear layer, thus permitting monomer diffusion into the demineralised collagen network. Hybridisation of dentine permits dental treatments not previously possible. The resulting structure is neither resin nor dentine but a hybrid of both occurring below the dentine surface and within the substrate. The process, a form of tissue engineering, completely changes the physical and chemical properties of dentine and allows many new ultra - conservative therapeutic modalities. The current paper focuses on the hybrid layer [or as sometimes referred to, the inter-diffusion zone] though this does not exclude the possibility of chemical bonding involving both mineral and protein constituents of dentine.