In vitro effects of alcohol-containing mouthwashes on human enamel and restorative materials

Abstract

The objective of this study was to evaluate the in vitro effects, including surface morphological characteristics and chemical elemental properties, of different mouthwash formulations on enamel and dental restorative materials, simulating up to 6 months of daily use. Human enamel samples, hydroxyapatite, composite resin, and ceramic surfaces were exposed to 3 different mouthwashes according to label directions - Listerine® Cool Mint®, Listerine® Total Care, and Listerine® Whitening - versus control (hydroalcohol solution) to simulate daily use for up to 6 months. The samples were analyzed using scanning electron microscopy (SEM), infrared spectrophotometry (µ-Fourier transform infrared microscopy), energy-dispersive X-ray (EDX) spectroscopy, and color analysis before and after exposure. No relevant changes were observed in the morphological characteristics of the surfaces using SEM techniques. The physical and chemical aspects of the enamel surfaces were evaluated using mid-infrared spectroscopy, and EDX fluorescence was used to evaluate the elemental aspects of each surface. There was no variation in the relative concentrations of calcium and phosphorus in enamel, silicon and barium in composite resin, and silicon and aluminum in the ceramic material before and after treatment. No relevant changes were detected in the biochemical and color properties of any specimen, except with Listerine® Whitening mouthwash, which demonstrated a whitening effect on enamel surfaces. Long-term exposure to low pH, alcohol-containing, and peroxide-containing mouthwash formulations caused no ultra-structural or chemical elemental changes in human enamel or dental restorative materials in vitro.

Effect of mouth rinses on tooth enamel surface

“…By observing the samples' mean values of ΔE, it was verified that the LW group showed the highest color variation and differed from the other groups subjected to immersion in mouth rinses as well as from the control group, which did not present a clinically significant change (ΔE < 3.7) [7,20]; but the groups treated with other mouth rinses also presented significant color variation similar to one another and different than the LW and CG groups. This result corroborates previous studies [2,8] and the results obtained by Torres et al [4], which demonstrated color changes promoted in tooth enamel by Listerine Whitening and Colgate Plax Whitening similar to conventional bleaching with 10% carbamide peroxide gel. This effect can be explained by time of use, although these agents have low hydrogen peroxide concentration and were used for a long period of time (12 weeks).…”

“…However, in an in vitro study, Pelino et al [8], contrary to the findings of the present study, found no changes in tooth enamel structure after the use of different mouth rinses simulating the application for 90 and 180 days, using daily cycles 30 or 60 min, respectively; however, when simulating a long period of daily application with different cycles of immersion times and intervals, the study did not comply with the protocol of daily clini-cal use regarding brushing, immersion time, interval, and total period of treatment as indicated by the manufacturers and adhered to in the present study. This may produce different results than what occurs clinically since brushing one's teeth with fluoride toothpaste prior to or after immersion in the mouth rinses, as indicated by the manufacturers and performed in the present study, may result in changes in the enamel surface not detected in Pelino et al's study [8].…”

“…Mouth rinses are also OTC products and are essentially composed of water, antimicrobials, a coloring agent, and salts [5]; sometimes alcohol is used as solubilizer and preservative [7,8], and hydrogen peroxide or a bleaching agent [2,5,6,8] is used in concentrations of approximately 3% to 6% [1]. It is known that some mouth rinses showed efficacy when used as bleaching agents as described by Torres et al [4] and Lima et al [2]; however, the daily contact of such products for a long period of time without professional supervision can promote changes in the surface of the tooth enamel.…”

“…It is known that some mouth rinses showed efficacy when used as bleaching agents as described by Torres et al [4] and Lima et al [2]; however, the daily contact of such products for a long period of time without professional supervision can promote changes in the surface of the tooth enamel. The implication of continuous or prolonged use of mouth rinse is still controversial; studies suggest that continuous use can cause changes in the surface of the tooth enamel [2,5,9,10], while there are authors [8] who did not find significant alterations in human tooth enamel subjected to mouth rinse by simulating a daily application period with cycles of immersion times and intervals different than those indicated by the manufacturers and that correspond to daily clinical practice. Furthermore, patients have been increasingly concerned about more effective oral hygiene habits; the use of chemical control agents (i.e., mouthwash) has been adopted to complement tooth brushing and flossing.…”

Colour stability and surface properties of high‐translucency restorative materials for digital dentistry after simulated oral rinsing

“…Several studies have reported that acidic solutions, including cola, orange juice, red wine, coffee, and gastric acid, can change the optical properties and surface roughness of toothcoloured dental restorative materials (10)(11)(12)(13)(14)(15). In addition, several oral hygiene solutions currently on the market can also affect the colour of dental restoration materials (16)(17)(18). Indeed, several brands of mouthwashes have a blue or green colour, which apparently is added to make them more visually appealing.…”