Clinical evaluation of three desensitizing agents in relieving dentin hypersensitivity.

OBJECTIVES: This in vivo study determined whether the application of three different desensitizing agents on exposed dentin surfaces was effective in reducing dentin hypersensitivity in subjects with slight-to-moderate sensitivity. METHODS: Sixty patients with a history of sensitivity were included in this study. At baseline visit, the initial sensitivity levels were recorded using a visual analog scale (VAS). In order to activate the sensitivity, evaporative (air-blast) and thermal (chloraethyl) stimuli were applied to each subject. The subjects' responses to the stimuli were marked on the VAS. Then, the subjects were assigned to one of the treatment groups or to a placebo. The agents used were Seal&Protect (Dentsply DeTrey GmbH, Konstanz, Germany), Vivasens (Ivoclar Vivadent AG, Schaan, Liechtenstein) and BisBlock (BISCO, Schaumburg, IL, USA); whereas, distilled water was used as the placebo. The subjects were recalled after four weeks, and their responses were again recorded. RESULTS: The VAS scores of the treatment and placebo groups were not different from each other at baseline (p > 0.05), and thermal stimuli caused higher patient discomfort than evaporative stimuli (p < 0.05). Alleviation effects of the desensitizing agents were not significantly different from each other; however, the placebo was an exception (p < 0.05). The differences between the VAS scores at baseline and after four weeks were significant for all three desensitizing agents (p < 0.05). However, in the placebo group, the evaporative stimuli led to insignificant pain variations (p > 0.05). CONCLUSION: It was concluded that the desensitizing agents used in this clinical study were effective in alleviating dentin hypersensitivity. Meanwhile, the placebo response was shown to play a significant role.

Effect of bleaching agents on calcium loss from the enamel surface.

OBJECTIVES: To compare the Ca2+ loss of enamel treated with 38% hydrogen peroxide (HP), 35% HP with light, and 10% carbamide peroxide (CP). METHOD AND MATERIALS: Ten extracted premolars were sectioned buccolingually and longitudinally so that 4 specimens were obtained from each tooth. The specimens were randomly assigned to 1 of 4 groups to receive the following bleaching agents: 38% HP, 35% HP with light, 10% CP, and no agent (control). The specimens were treated with an artificial caries solution (pH 4) for 16 days; the solution was replaced on days 4, 8, 12, and 16. Calcium concentration was determined by an atomic absorption spectrophotometer. Repeated measures ANOVA was performed on concentrations on days 4, 8, 12, and 16. RESULTS: At the end of day 16, calcium ions released per square millimeter were calculated cumulatively as follows: 38% HP group: 27.52 +/- 5.22 microg/mL; 35% HP with light group: 25.15 +/- 4.99 microg/mL; 10% CP group: 19.53 +/- 4.03 microg/mL; control group: 18.35 +/- 4.00 microg/mL. The differences between the control group and the 35% HP with light group and between the control group and 38% HP group were statistically significant. Although demineralization differences were observed between the control group and the 10% CP group, this difference was not significant. CONCLUSIONS: It can be concluded that 35% HP with light and 38% HP may cause significantly more loss of Ca2+ from the enamel surfaces than 10% CP. Also, 10% CP does not vary significantly from the control.

Shear bond strengths of three different resin luting cements to bovine teeth.

This study evaluated the shear bond strengths of dentin/porcelain and enamel/ porcelain specimens bonded with three different dual-cure cements. The specimens were prepared using the heat-pressed ceramic technique. Three different dual-cure cements were used to bond samples to previously prepared bovine enamel and dentin surfaces. The specimens were thermocycled and tested in shear until failure. The shearbond data was subjected to one-way ANOVA, followed by Duncan's multiple range test at a significance level of p < 0.05. The shear bond strengths of Variolink II were significantly higher than those of Rely-X ARC and Panavia F for enamel and dentin (p < 0.05). Bond strenghts in enamel were higher than those of dentin in all materials (p < 0.05).