The earlier resin bonded materials, developed as tooth coloured materials, were detrimental to the pulp. The free monomer of these self cured or chemically cured materials was injurious to the health of the pulp. Over the years, with the development of composites and also the tremendous improvements in the material aspect of these resins, the pulp effects are minimum but not absent.
The bond strength of these materials is linked to the etching of the normal mineralized tissue. The etching, since being carried out for 10-15 seconds only, its effect on pulp is minimum or negligible.
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| Etched surface |
To achieve optimal bonding to dentin, the adhesive material (bonding agents) must penetrate the demineralized dentin; enter the dentinal tubules and their branches.
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| Demineralised dentin |
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| Dentinal tubules |
The resin monomer enters the collagen fibers to completely infiltrate the demineralized dentin forming the hybrid layer and over this the composite is filled.
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| Infiltration of resin monomer |
The bonding materials have been tried as ‘pulp capping agents’ with reasonably good results. It imparts healing process. However, the polymerization shrinkage of the composite creating vacuum in between the remaining dentin and the restoration might create problems for the pulp. It has been established that even after curing, the monomer is leached from composites. However, the monomer is usually neutralized by the bonding agents and the remaining dentin thickness. In case the dentin thickness below the composites is less, the leaching monomer can affect the underlying pulp.
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