This in vitro study examined the sealing ability of different desensitizing agents under a chemo-mechanical stress condition. For the study, a total of 144 extracted, caries-free human third molars were used to produce 1 mm-thick dentin discs. The specimens were divided randomly into four groups: Superseal (SS), Gluma (GL), Gluma Self-etch (GS), and Tooth Coat (TC). For each group, the permeability was measured before and after applying the desensitizer, after being exposed to Coca Cola for 5 minutes, and after 3150 strokes of a brushing abrasion. The decrease in permeability after the erosive and abrasive stress was analyzed by ANOVA and Tukey post hoc test. As a result, the dentin permeability decreased significantly for all desensitizers immediately after application (p < 0.05). SS and GS showed a significant difference in permeability reduction observed immediately after application and after acid action with Coca Cola (p < 0.05). After brushing abrasion, the permeability reduction decreased significantly for all desensitizers tested in this study (p < 0.05). TC showed the largest decrease in dentinal permeability compared to that of the other desensitizers and the differences were significant after brushing abrasion (p < 0.05). All tested desensitizers were effective in reducing dentin permeability. The behavioral characteristics under erosive and abrasive stress varied according to the products used. TC exhibited excellent sealing ability among the other desensitizers.

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The purpose of this study was to evaluate the effect of oil lubricant for dental handpiece and to investigate the relationship to the prognosis of dental implants. Materials and Methods:An experiment was conducted on the residual amount of lubricant in the handpiece and the amount of lubricant that will remain in the fixture after drilling. Based on the data, biocompatibility was assessed through the assessment of cytotoxicity with L929 cells and 33 SD rats. This experiment was conducted through an 8 mm-long, 3.5 mm-diameter fixture(Osstem implant Co., Ltd., Korea) and lubricant(KaVo Dental GmbH., Germany) for handpiece. Results:The amount of lubricants in the handpiece decreased with the removal phase, but some of them could be confirmed to remain. In the cytotoxicity assessment, the survival rate was lower over 100 ppm. In experiments with SD rat, there was no significant difference among groups. Conclusion:The surface of the dental implants could be contaminated from some leftover lubricants in the handpiece. Although the lubricant is the biocompatible in cytotoxicity test and SD rat test, it does not mean it has no effect on osseointegration.

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