Effect of Erosion/Abrasion Challenge on the Dentin Tubule Occlusion Using Different Desensitizing Agents.

The aim of the study was to evaluate dentinal tubule occlusion, measuring the dentin permeability (Lp) and using different desensitizing agents before and after abrasive/erosive challenge. Dentin discs from 42 healthy human third molars were obtained. Minimum Lp was measured after a smear layer simulation using #600 SiC paper and maximum Lp after an immersion in 0.5 M EDTA. The specimens were treated with different desensitizers: two varnishes (Clinpro XT Varnish-CV, Fluor Protector-FP), a paste (Desensibilize Nano P-NP) and a gel (Oxa Gel-OG). The Lp of each specimen was measured immediately after the desensitizers' application. The discs were subjected to erosion/abrasion cycles for 7 days, with 0.5% citric acid solution (6x/day) and tooth brushing (3x/day). Lp was measured after the first, fourth and seventh day of the challenge. The data were analyzed by 3-way ANOVA with repeated measurements and by a Games-Howell test (α=5%). FP and CV did not show significant differences in Lp immediately after application until the 7th day (p<0.05). OG showed a significant increase in Lp after the 4th and 7th days. NP resulted in a significantly higher permeability compared to the other materials immediately after the application and after the 1st day of challenge. All the desensitizers reduced the dentin permeability immediately after application. However, only the varnishes were able to maintain the occlusive effect after the erosion/abrasion challenge.