Effect of dentin desensitizers and dentin bonding agents on dentin permeability

To determine the effect of dentin desensitizing agents (oxalates and glutaraldehyde) and dentin bonding agents, with and without resin-based composite (RBC) on dentin permeability and morphology of the dentin surface. The influence of saliva and toothbrushing on these agents was also evaluated.

Radicular dentin discs +/-1 mm thick were obtained from extracted human teeth. The thickness of the discs was standardized by grinding them with 600 grit silicon carbide powder. Both pulpal and periodontal surfaces of the discs were treated with 6% citric acid for 2 min prior to the baseline measurement of dentin permeability. Permeability was measured for the discs, using a split-chamber apparatus, at four different time points: at baseline, after treatment with each desensitizing modality, after 24 hrs of saliva immersion and after simulated toothbrushing equivalent to 3 weeks of normal brushing. The treatment modalities were: Sensodyne Dentin Desensitizer, Gluma Dentin Desensitizer, All-Bond DS (primers without etching), Etch+Primers (All-Bond 2 system), Etch+Primers+Adhesive and Etch+Primers+Adhesive+RBC (AElite Flo). Radicular dentin discs were prepared separately for scanning electron microscopy (SEM). One group was left untreated as the control group. Discs in the other groups were treated with the modalities listed above. One disc from each group was viewed under the SEM after treatment with the desensitizing modality. The second disc in each group was viewed after 24 hrs of saliva immersion following desensitizing treatment and the third disc after 3 weeks of simulated toothbrushing following desensitizing treatment and saliva immersion.

The greatest reduction in permeability was caused by All-Bond DS followed by Sensodyne Dentin Desensitizer and Etch+Primers+Adhesive+RBC. Gluma Dentin Desensitizer, Etch+Primers, and Etch+Primers+Adhesive did not reduce permeability by a significant amount. Saliva immersion increased permeability significantly only for the Gluma and Etch+Primers+Adhesive groups. There was a trend towards increase in permeability after toothbrushing; however, this increase was not statistically significant for any group (P > 0.05). Thus, placement of primers without etching (All-Bond DS) reduced permeability more than any other treatment modality. These data indicate that etching a sensitive dentin area may be appropriate only if RBC is to be placed in the area. Exposure to saliva and toothbrushing countered the decrease in permeability caused by dedicated desensitizers and dentin bonding agents. The SEM micrographs revealed that in most cases, form corroborated function and the morphology of the dentin surface corresponded to the dentin permeability values.