In vitro enamel erosion and abrasion-inhibiting effect of different fluoride varnishes

Highlights

• The authors investigated the erosive and abrasive inhibiting effect of CPP-ACP/NaF and xylitol/NaF varnishes on dental enamel.

• A single-application of fluoride topical varnishes was effective in reducing enamel wear.

• CPP-ACP/NaF varnish had the best effect against enamel loss from erosion-abrasion challenge.

• These findings provide a basis for future studies to determine the effect of CPP-ACP/NaF varnish in preventing clinical erosive tooth wear.

Abstract

Objective

To investigate the erosion and abrasion inhibiting effect of CPP-ACP/NaF and xylitol/NaF varnishes.

Methods

Bovine enamel samples (n = 40) were exposed to the following treatments (n = 10): NaF varnish (Duraphat^®, positive control); CPP-ACP/NaF varnish (MI varnishTM); xylitol/NaF (Profluorid^®) or distilled and deionized water (MilliQ^®, negative control). The samples were submitted for 3 days to 4 cycles/day of erosion (5 min in Sprite Zero) and 2 cycles of abrasion/day after the first and last erosive challenge, with a toothbrush machine and slurries of a placebo toothpaste for 15 s (50 strokes/s). Among the cycles and after the last daily cycle, the specimens remained in artificial saliva. The change in the enamel surface was evaluated by using 3D non-contact optical profilometry with surface roughness (Ra and Sa values) and tooth structure loss (TSL) measurements. Scanning electron microscopy (SEM) assessed the enamel topographic characteristics. Differences in the Ra, Sa and TSL among treatments were tested using one-way ANOVA followed by the Tukey test.

Results

All varnishes promoted better results for Ra and Sa values than the negative control (p = 0.0001), without difference among them (p > 0.05). However, CPP-ACP/NaF varnish stimulated fewer TSL (7.09 ± 0.70 μm) compared to NaF varnish (10.33 ± 1.36 μm, p = 0.002), xylitol/NaF varnish (9.96 ± 0.41 μm, p = 0.007) and the negative control (18.38 ± 3.32 μm, p = 0.0001).

Conclusion

A single-application of fluoride topical varnishes was effective in reducing enamel wear. The CPP-ACP/NaF varnish had the best effect against enamel loss from an erosion-abrasion challenge.

Introduction

Dental erosion is defined as an irreversible loss of tooth tissue by exogenous or endogenous acids without bacterial involvement (Huysmans, Chew, & Ellwood, 2011), accompanied by a progressive softening of the superficial and near-surface layer of enamel. (Huysmans et al., 2011, Lussi and Carvalho, 2014, Lussi and Carvalho, 2015; Shellis, Barbour, Jesani, & Lussi, 2013). This softening surface turns less resistant, increasing the susceptibility to physical wear such as toothbrush abrasion (Ganss, Lussi, & Schlueter, 2014; Rios et al., 2006). Thus, the application of high concentrations of fluoride, especially varnish formulations, has been described to decrease the development of tooth enamel erosion and increase abrasion resistance (Lippert, 2014; Sar Sancakli, Austin, Al-Saqabi, Moazzez, & Bartlett, 2015).

The potential of sodium fluoride (NaF) and stannous fluoride to prevent dental erosion with efficacy has been described in the literature (Algarni et al., 2015; Sorvari, Meurman, Alakuijala, & Frank, 1994; Vieira, Jager, Ruben, & Huysmans, 2007). Recently, other products than fluoride, as casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and Xylitol, have been studied to observe their protective effect against erosion or abrasion.

CPP-ACP is the Recaldent™ technology based on amorphous calcium phosphate (ACP) stabilized by casein phosphopeptides (CPP). The benefits of CPP-ACP nanocomplexes are the high concentration of calcium and phosphate ions that promote enamel remineralisation. In the presence of fluoride ions, there is the production of an ACFP phase (CPP-ACP addicted with fluoride ion), which may contribute to remineralisation when the fluoride ions are disassociated (Cross, Huq, & Reynolds, 2007; Reynolds et al., 2008). Whereas the xylitol is a non-acidogenic sweetener (Makinen, 2010) able to form complexes with calcium ions (Makinen, 2010; Miake, Saeki, Takahashi, & Yanagisawa, 2003). Due this property, some authors believe that xylitol might enhance remineralisation and inhibit the dissolution of calcium and/or phosphate ions from enamel structure (Chunmuang, Jitpukdeebodintra, Chuenarrom, & Benjakul, 2007; Miake et al., 2003; Vongsavan, Surarit, & Rirattanapong, 2014). However, the role of xylitol has not been enough demonstrated as a preventive or remineralising agent (Tuncer, Onen, & Yazici, 2014)

Taking into account that in the researched literature no studies evaluating, at the same time, the effect of CPP-ACP/NaF and Xylitol/NaF varnishes with regard to erosion and abrasion, the purpose of the present study was to investigate the enamel erosion and abrasion-inhibiting effect of NaF fluoride varnishes with or without CPP-ACP and Xylitol.