A randomised clinical trial investigating calcium sodium phosphosilicate as a dentine mineralising agent in the oral environment
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.
References (22)
- et al.
Prevalence of dentine hypersensitivity and study of associated factors: a European population-based cross-sectional study
Journal of Dentistry
(2013) - et al.
Effect of pH and ionic strength on the reactivity of Bioglass 45S5
Biomaterials
(2005) - et al.
Dentine remineralization induced by two bioactive glasses developed for air abrasion purposes
Journal of Dentistry
(2011) - et al.
In situ atomic force microscopy of partially demineralised human dentine collagen fibrils
Journal of Structural Biology
(2002) - et al.
Effect of desensitising toothpastes on dentineal tubule occlusion: a dentine permeability measurement and SEM in vitro study
Journal of Dentistry
(2010) The story of bioglass
Journal of Material Science. Materials in Medicine
(2006)- et al.
Direct chemical bond of bioactive glass-ceramic materials to bone and muscle
Journal of Biomedical Materials Research Symposium
(1973) NovaMin and tooth sensitivity – an overview
Journal of Clinical Dentistry
(2010)- et al.
A comparative in vitro study investigating the occlusion and mineralization properties of commercial toothpastes in a four-day dentine disc model
Journal of Clinical Dentistry
(2011) - et al.
The dentine remineralization activity of a desensitizing bioactive glass-containing toothpaste: an in vitro study
Australian Dental Journal
(2011)