Evaluation of a natural resin-based new material (Shellac F) as a potential desensitizing agent

To evaluate the cytotoxicity of Shellac F, a new fluoride varnish, and its effects on human dentin hydraulic conductance.

Shellac F was compared to another fluoride varnish (Duraphat) and a fluoride containing desensitizing agent (Isodan). The cytotoxicity test was performed on human gingival fibroblasts and through dentin slice on human pulp fibroblasts. The hydraulic conductance (Lp) was recorded by fluid filtration with a Flodec device under a constant pressure (15 cm H2O). The treated surface of the dentin disks and their sections were also investigated with SEM.

The cytotoxicity test on gingival fibroblasts revealed that Duraphat was the least cytotoxic material, followed by Shellac F then Isodan. With dentin slice interposition, a lower level of cytotoxicity was obtained. All of them showed a lower cytotoxicity decreasing on further dilutions (p<0.001). The measurement of hydraulic conductance showed that all materials resulted in a significant decrease in dentin permeability after 24h comprising between 60 and 76%, but there was no statistically significant difference among the materials. This decrease was still over 50% of the initial values after 7 days for all three materials. SEM investigation showed dentin tubules covered with a thick layer of Shellac F or Duraphat whilst no material was observed on dentin surfaces treated with Isodan.

Shellac F showed an adequate cellular compatibility and a significant effect on human dentin hydraulic conductance. This indicates that the new material is safe and seems to be effective as a potential desensitizing agent.