Effects of two desensitizing dentifrices on dentinal tubule occlusion with citric acid challenge: Confocal laser scanning microscopy study

Background: Dentin hypersensitivity results when patent tubules are exposed to pain-inducing external stimuli. Aim: This study aims to compare the effects of two desensitizing dentifrices containing NovaMin and arginine on dentinal tubule occlusion with and without citric acid challenge in vitro using confocal laser scanning microscopy (CLSM). Materials and Methods: Forty dentin discs were randomly divided into Groups I and II containing twenty specimens each, treated with NovaMin and arginine-containing dentifrices, respectively. Groups I and II were divided into subgroups A and B where IA and IIA underwent CLSM analysis to determine the percentage of tubule occlusion while IB and IIB underwent 0.3% citric acid challenge and CLSM analysis. A novel grading system was devised to categorize tubule occlusion. Results: In Group II, the percentage of occluded tubules was highest for IIA (72.25% +- 10.57%) and least for IIB (42.55% +- 8.65%) having statistical significance (P < 0.0005). In Group I, the difference between IA (49.9% +- 12.96%) and IB (43.15% +- 12.43%) was statistically insignificant (P = 0.249). On the comparison between IB and IIB statistically indifferent result was obtained (P = 0.901), whereas the difference between IA and IIA was statistically significant (P < 0.001). The results of grading system were for IA 50% of samples belonged to Grade 2, for IIA 60% - Grade 3, and for IB 70% and for IIB 90% - Grade 2. Conclusion: Dentinal tubule occlusion with arginine-containing dentifrice was significantly higher than NovaMin. However, it could not resist citric acid challenge as effectively as NovaMin. The effects of NovaMin were more sustainable as compared to arginine-containing dentifrice, thus proving to be a better desensitizing agent.