Randomized clinical trial to determine if changes in dentin tubule occlusion visualized by SEM of replica impressions correlate with pain scores.

PURPOSE: To quantify dentin tubule occlusion and correlate this with pain reduction in vivo. METHODS: This was a single-center, randomized two treatment, examiner-blind, parallel study. 20 participants with confirmed dentin hypersensitivity (DH) were evaluated by Schiff Air Blast, VAS Air Blast and replica impression of the tooth surface to visualize tubule occlusion at baseline and following 4-week twice daily use of either an occluding toothpaste (8% strontium acetate, 1,040 ppm fluoride) or a non-occluding toothpaste (1,450 ppm fluoride). RESULTS: Both treatments increased tubule occlusion significantly from baseline to 4 weeks (P= 0.01) with significant decreases in pain score only seen with the occluding toothpaste (Schiff, P= 0.01; VAS, P= 0.01). Schiff pain score after 4 weeks was markedly reduced following treatment with the occluding toothpaste as compared to the non-occluding toothpaste, (P= 0.05) with no significant differences between the pastes for occlusion score or patient reported VAS, although the scores favored the occluding toothpaste. CLINICAL SIGNIFICANCE: Occlusion scores as obtained by replica impression techniques with SEM imaging correlate significantly with DH pain scores confirming proof of concept. With further refinement, this technique could be used to accurately quantify tubule occlusion in vivo and the associated pain reduction achieved by occluding toothpastes.

Assessment of tubule occlusion properties of an experimental stannous fluoride toothpaste: A randomised clinical in situ study.

OBJECTIVES: To evaluate the ability of a modified in situ model to differentiate dentinal tubule occlusion properties of toothpaste formulations over 10 days of treatment. METHODS: This was a single-centre, three-treatment period, crossover, randomised, single-blind study with healthy participants wearing two lower oral appliances, each retaining four dentine samples, for 10 treatment days during each period of the study. Samples were power-brushed ex vivo twice on each treatment day with a Test toothpaste containing 0.454% stannous fluoride, a Control fluoride toothpaste containing 0.76% sodium monofluorophosphate, or mineral water. Dentine samples were subjected to in situ acid challenge (orange juice) on Days 9 and 10. Scanning electron microscopy images obtained at baseline and after 1, 4, 8 and 10 days of treatment were graded for degree of surface coverage by four calibrated examiners; the primary study endpoint was Day 8. RESULTS: After 4, but not 8, days' treatment, the degree of tubule occlusion increased in the dentine samples treated with the Test or Control toothpastes compared with the water-treated samples (p < 0.01 and p < 0.05, respectively). Following the acid challenge (Day 10), there was a statistically significantly greater degree of occlusion in the Test toothpaste-treated dentine samples compared with those treated with water (p < 0.01). No other comparisons were statistically significant. All study treatments were generally well-tolerated. CONCLUSIONS: This modified in situ model was unable to demonstrate statistically significant between-treatment differences in dentinal tubule occlusion after 8 days. Conversely, there are recognised developments that could be made to better identify product differences. Clinicaltrials.gov: NCT02768194. CLINICAL SIGNIFICANCE: Dentine hypersensitivity can be managed through brushing with stannous fluoride toothpastes, which occlude patent dentine tubules. Clinical studies measure pain but in situ models are needed to demonstrate occlusion intra-orally. However, this study did not demonstrate superior occlusion with stannous toothpaste; further methodological development is required to investigate its mode of action.

In vivo model for microbial invasion of tooth root dentinal tubules.

Objective Bacterial penetration of dentinal tubules via exposed dentine can lead to root caries and promote infections of the pulp and root canal system. The aim of this work was to develop a new experimental model for studying bacterial invasion of dentinal tubules within the human oral cavity. Material and Methods Sections of human root dentine were mounted into lower oral appliances that were worn by four human subjects for 15 d. Roots were then fixed, sectioned, stained and examined microscopically for evidence of bacterial invasion. Levels of invasion were expressed as Tubule Invasion Factor (TIF). DNA was extracted from root samples, subjected to polymerase chain reaction amplification of 16S rRNA genes, and invading bacteria were identified by comparison of sequences with GenBank database. Results All root dentine samples with patent tubules showed evidence of bacterial cell invasion (TIF value range from 5.7 to 9.0) to depths of 200 mm or more. A spectrum of Gram-positive and Gram-negative cell morphotypes were visualized, and molecular typing identified species of Granulicatella, Streptococcus, Klebsiella, Enterobacter, Acinetobacter, and Pseudomonas as dentinal tubule residents. Conclusion A novel in vivo model is described, which provides for human root dentine to be efficiently infected by oral microorganisms. A range of bacteria were able to initially invade dentinal tubules within exposed dentine. The model will be useful for testing the effectiveness of antiseptics, irrigants, and potential tubule occluding agents in preventing bacterial invasion of dentine.

A randomised clinical trial investigating calcium sodium phosphosilicate as a dentine mineralising agent in the oral environment.

OBJECTIVE: The ability of a dentifrice containing the bioactive material calcium sodium phosphosilicate (CSPS) to remineralise the surface of dentine and physically occlude patent tubules was investigated in a 20 day in situ randomised clinical study. METHODS: Changes in surface microhardness and surface topography of dentine specimens treated for 5, 10, 15 and 20 days, twice daily with either a dentifrice containing 5% CSPS or a fluoride-only containing placebo dentifrice were compared. The substantivity of any mineral deposits formed on the surface of dentine were investigated by the application of an intra-oral dietary acid challenge twice daily during the final 10 days of treatment. RESULTS: After 5 and 10 days of treatment, the dentine samples in both treatment groups demonstrated an increase in surface microhardness. After 10 days of treatment the increase in surface hardness was directionally greater for the specimens treated with 5% CSPS dentifrice. Introducing an intra-oral acid exposure resulted in a reduction in surface microhardness which was significantly greater for the specimens treated with the placebo dentifrice compared to the dentifrice containing 5% CSPS, at day 20. Occlusion of the patent tubules was evident at each time-point and was significantly greater for the 5% CSPS containing dentifrice on days 5 and 10. On day 15 both dentifrices demonstrated the same degree of occlusion. CONCLUSION: This in situ study demonstrated that dentifrice containing 5% CSPS may have potential to mineralise and occlude the dentine in the oral environment. CLINICAL SIGNIFICANCE: This work provides evidence of potential agents that can be used to reduce the pain of dentine hypersensitivity when formulated into dentifrice and applied as part of a normal oral hygiene routine.

In vivo model for microbial invasion of tooth root dentinal tubules

ABSTRACT Objective Bacterial penetration of dentinal tubules via exposed dentine can lead to root caries and promote infections of the pulp and root canal system. The aim of this work was to develop a new experimental model for studying bacterial invasion of dentinal tubules within the human oral cavity. Material and Methods Sections of human root dentine were mounted into lower oral appliances that were worn by four human subjects for 15 d. Roots were then fixed, sectioned, stained and examined microscopically for evidence of bacterial invasion. Levels of invasion were expressed as Tubule Invasion Factor (TIF). DNA was extracted from root samples, subjected to polymerase chain reaction amplification of 16S rRNA genes, and invading bacteria were identified by comparison of sequences with GenBank database. Results All root dentine samples with patent tubules showed evidence of bacterial cell invasion (TIF value range from 5.7 to 9.0) to depths of 200 mm or more. A spectrum of Gram-positive and Gram-negative cell morphotypes were visualized, and molecular typing identified species of Granulicatella, Streptococcus, Klebsiella, Enterobacter, Acinetobacter, and Pseudomonas as dentinal tubule residents. Conclusion A novel in vivo model is described, which provides for human root dentine to be efficiently infected by oral microorganisms. A range of bacteria were able to initially invade dentinal tubules within exposed dentine. The model will be useful for testing the effectiveness of antiseptics, irrigants, and potential tubule occluding agents in preventing bacterial invasion of dentine.