Influence of Erosion/Abrasion and the Dentifrice Abrasiveness Concomitant with Bleaching Procedures

Priscila Christiane Suzy Liporoni,1,2 Wan Zaripah Wan Bakar,3 Rayssa Ferreira Zanatta,1 Glaucia Maria Ambrosano,4 Flávio Henrique Baggio Aguiar,5 Bennett T Amaechi2 1Department of Restorative Dentistry, University of Taubaté, Taubaté, SP, Brazil; 2Department of Comprehensive Dentistry, University of Texas Health Science Center at San Antonio, San Antonio, TX, USA; 3School of Dental Sciences, Universiti Sains Malaysia Health Campus, 16150 Kubang Kerian, Kelantan, Malaysia; 4Department of Community Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, SP, Brazil; 5Department of Restorative Dentistry, Piracicaba Dental School, University of Campinas, Piracicaba, SP, BrazilCorrespondence: Flávio Henrique Baggio AguiarUniversity of Campinas - Piracicaba Dental School, Av. Limeira, 901, bairro Areao Piracicaba, SP, BrazilEmail baguiar@unicamp.brPurpose: The aim of this study was to evaluate the effect of erosive/abrasive cycles and two different levels of abrasiveness of dentifrices over enamel and dentin subjected to bleaching.Methods: Enamel and dentin bovine specimens were prepared and submitted to an at-home bleaching treatment using 9.5% hydrogen peroxide gel, which was applied daily (30 min/14 days). Concomitant with bleaching, an erosive cycle was performed using citric acid (0.3%, pH 3.8, 5 mins, 3×/day), followed by immersions in artificial saliva for remineralization (30 mins). Abrasion was done with two (high and low abrasiveness) dentifrices (2×/day, 120 seconds) after the first and third erosive immersion each day. Enamel and dentin softening were assessed by microhardness and erosive tooth wear by optical profilometry. Data were submitted to repeated measures ANOVA, followed by the Tukey’s test with a significance level of 5%.Results: For the enamel and considering the erosive-abrasive cycle, significant differences were found between the groups tested, the bleaching, and the abrasiveness of the dentifrice tested; however, the final microhardness values were significantly lower than the initial ones. For dentin, differences were found between the eroded/abrasion and the non-eroded/abrasion groups, with the former presenting lower microhardness values compared with the latter. In addition, bleaching decreased the microhardness values only for the highly abrasive dentifrice, and the final values were lower than for the initial ones for all tested groups.Conclusion: The use of high and low abrasiveness dentifrices during bleaching and concomitant with erosion/abrasion cycles is more harmful to dentin than to enamel.Clinical Relevance: Although bleaching is considered a conservative treatment, it can cause deleterious effects to dental hard tissue. The association of an at-home bleaching technique with erosion and high- or low- abrasive dentifrices harms dentin more than enamel.Keywords: bleaching, enamel, dentin, erosion, wear