Elsevier

Journal of Dentistry

Volume 43, Issue 6, June 2015, Pages 757-764
Journal of Dentistry

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

https://doi.org/10.1016/j.jdent.2014.10.005Get rights and content

Abstract

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.

Introduction

Described as a sharp but transient pain arising in response to a stimuli, dentine hypersensitivity (DH) is a rather common condition affecting up to 42% of the population.1 The origin of DH is generally agreed to result from the exposure of dentine, following either loss of the protective enamel layer or via gum recession, and the development of patent tubules. Currently, a number of inorganic materials are employed in a variety of dentifrice formulations with the aim of depositing material in or on dentine to physically occlude patent dentine tubules and provide relief from the pain of DH.

Calcium sodium phosphosilicate (CSPS) is an ingredient found in a number of professional use and over-the-counter dental products designed to provide relief from DH. CSPS is a bioactive glass (CaO-Na2O-P2O5-SiO2) and was originally developed as bone repair material in the early 1970s.2 CSPS has been reported to form a direct bond with calcified tissue following exposure to an aqueous environment.3 Once in an aqueous environment CSPS has been reported to undergo a series of chemical reactions that result in an increase of the local pH to approximately 9. This creates an environment suitable for silica release, formation of a porous silica gel surface and the formation of calcium apatite.2, 4 A reservoir of calcium and phosphate is formed beneath the silica gel and these ions are released into the aqueous environment through the porous surface. CSPS incorporated in dentifrice formulations has been reported to physically occlude dentine tubules,5 increase dentine mineralization6, 7 and provide relief from the pain of DH. In vitro,6, 8 in situ9 and clinical efficacy studies10, 11, 12, 13, 14 have demonstrated significant levels of dentine occlusion and relief from dentine hypersensitivity, following treatment with CSPS containing dentifrices.

The primary objective of this exploratory in situ study was to evaluate the dentine mineralisation potential of a dentifrice, containing 5% (w/w) CSPS and 1450 ppm fluoride (as sodium monofluorophosphate) compared to baseline and to a CSPS-placebo dentifrice containing 0% CSPS and 1450 ppm fluoride (as sodium monofluorophosphate). Further exploratory objectives were to: (i) evaluate changes in surface topography conferred by the test dentifrices. The null hypothesis being tested was that the addition of 5% CSPS to the dentifrice would not provide an increase in remineralisation or an increase in tubular occlusion and, (ii) to evaluate for each treatment, the influence of acid challenge on dentine mineralisation (surface microhardness), dentine tubule occlusion (scanning electron microscopy) and dentine tissue loss (noncontact profilometry) by comparing assessment results of Day 20 to those of Day 10 using an in situ model.

Section snippets

Study design and methodology

This study was a single centre, single blind (persons responsible for sample analysis), randomised, two treatment, two period crossover design, exploratory in situ study in healthy participants.

During the treatment phase, each participant wore a lower right and left buccal appliance holding 4 dentine specimens each. Specimens in both appliances were treated with the same dentifrice for 20 days (non-consecutive days – Monday to Friday only) with a wash out period of 48 h preceding a second

Surface microhardness (SMH)

The primary efficacy endpoint for this exploratory study was the change from baseline in SMH to all time-points with the main interest on treatment differences. Table 1 and Fig. 2 present mean SMH as a function to Treatment and Day. Although not a powered study, for the Per Protocol (PP) population a statistically significant treatment difference was detected for the Day 20 time-point (p-value = 0.0109). At this time-point, a decrease from baseline in SMH was observed for both treatments but the

Discussion

In vitro models are indispensable for preliminary investigations regarding the mechanism of action and potential efficacy of therapeutic agents; however there is no substitute for the oral environment and dietary influences. In situ models are widely employed to measure a variety of phenomena that occur in the oral environment, including enamel and dentine erosion, abrasion and caries. In situ models can utilise analytical techniques that cannot be used in vivo and can provide a bridge between

Conclusion

In conclusion, this exploratory in situ study has shown that a CSPS containing dentifrice may have potential to occlude and mineralise dentine in the oral environment, and withstand dietary acidic challenges thus we can reject the null hypothesis.

Conflicts of interests

There are no other conflicts of interests.

Acknowledgements

This study was funded and sponsored by GlaxoSmithKline Consumer Healthcare and conducted at The University of Bristol. Charles Parkinson and Peter Jeffery are employees of Glaxo Smith Kline Consumer Healthcare.

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