Biocompatibility of dentine-bonding agents. 2. Pulpal considerations

The paper reviews the literature concerning the biocompatibility of dentine-bonding agents. The literature review indicates that two main hypotheses are presented to explain pulpal inflammation following the placement of materials such as dentine-bonding agents, namely material toxicity and bacterial infection. The paper discusses the role of such factors as microbial microleakage, remaining dentine thickness and the smear layer as factors in determining material toxicity and summarises the reported biocompatibility studies. From this it is concluded that most bonding agents contain constituents which have a potential irritant or toxic effect on the pulpo-dentinal complex. The irritant effect may be due to constituents of the bonding agents, or to poor or lost bonding, or to a combination of all these factors. The recently favoured total-etch technique may cause an increase in dentine permeability by removal of the smear layer and thereby increase the irritant effect of some materials.