Penetration of dentin by different conditioners in vitro: a quantitative study

Abstract

Conditioning agents are known to remove the smear layer that forms on cut dentin with the resultant opening of the orifices of the dentinal tubules. However, much controversy exists over the depth to which these agents penetrate the residual dentin and whether they might damage the underlying pulp. In view of the enormous technical difficulties of studying the depth of penetration of such agents in vivo, an in vitro study was undertaken. Dentin slices of known thickness were prepared with an intact smear layer on both surfaces. The upper surface was treated with the test conditioner, and the depth of penetration was assessed using SEM by the degree of removal of the dentin plugs blocking the orifices of the dentin tubules in the lower untreated surface. No significant penetration of 200 μm slices occurred and only slight penetration of 100 and 50 μm slices. There was little difference in the degree of penetration achieved by the 5 agents studied. The results presented suggest that the chemical toxicity of the conditioners tested will not damage the pulp if the residual dentin depth is greater than 200 μm.