Method: Fifty coronal dentin discs (0.08±1.00mm thickness) were obtained from unerupted human third molars. The methodology used for the measurement of Lp was based on the model suggested by Pashley, Stewart and Galloway, 1984. In order to reduce variables, the discs selected had similar initial permeability. The discs were randomly allocated into 5 groups (n=10) according to dentin desensitizer used: G1- Potassium oxalate (experimental gel); G2- Sensitive Pro-Relief (Colgate®); G3- Fluoride gel (SS White); G4- Desensibilize Nano-P (FGM) and G5- Enamel Pro@ Varnish (Premier®). The Lp of each disc was recorded as: minimum Lp (with smear layer), maximum Lp (after etching with 37% phosphoric acid); after treatment (desensitizing agents) and after acid challenge (6% citric acid). The intra and intergroups differences were statistically analyzed by ANOVA and Tukey test, p<0.05. Qualitative analysis was obtained by Confocal Laser Scanning Microscopy.
Result:
Treatment |
Phase |
|||
|
minimum Lp |
maximum Lp |
treatment Lp |
acid challenge Lp |
G1 |
0,035A,a±0,022 |
0,534A,b±0,186 |
0,027A,a±0,016 |
0,027A,a±0,017 |
G2 |
0,016B,a±0,003 |
0,522A,b±0,228 |
0,352BC,c±0,153 |
0,458B,bc±0,223 |
G3 |
0,013BC,a±0,004 |
0,495A,b±0,192 |
0,450B,b±0,163 |
0,438B,b±0,140 |
G4 |
0,010CD,a±0,003 |
0,380A,b±0,173 |
0,219C,c±0,112 |
0,293B,bc±0,133 |
G5 |
0,007D,a±0,004 |
0,398A,b±0,163 |
0,316BC,bc±0,148 |
0,269B,c±0,141 |
Intergroups Lp: different capital letters in the same column = statistical difference.
Intragroups Lp: different small letters in the same line = statistical difference
Conclusion: Although all the desensitizing agents produced some Lp reduction when compared to maximum Lp, G1 was the most effective group. G3 and G5 showed the highest levels of fluid permeation. Only G1 maintained the treatment Lp values after acid challenge. The qualitative analysis showed different patterns of particles precipitation for the different desensitizers studied. Comparison with Lp results suggested that even in the presence of crystals under and inside the dentinal tubules, some desensitizers were not able to reduce dentin filtration.