title: In Situ and In Vitro Effects of Two Bleaching Treatments on Human Enamel Hardness.
abstract: The aim of this study was to evaluate in vitro and in situ the effects of two bleaching treatments on human enamel surface microhardness. Sixty enamel slabs from recently extracted thirty molars were used. The specimens were polished with sandpapers under water-cooling. The enamel samples were randomly divided in four groups, treated with 10% hydrogen peroxide (HP) or Whitening Strips (WS) containing 10% hydrogen peroxide and using two conditions: in vitro or in situ model. For in situ condition, six volunteers wore an intra-oral appliance containing enamel slabs, while for in vitro condition the specimens were kept in deionized water after the bleaching protocols. The bleaching treatments were applied one-hour daily for 14 days. Similar amounts of bleaching agents were used in both conditions. Before and after bleaching treatments, microhardness was measured. Statistical analysis (ANOVA and Tukey test) showed that in the in situ condition there was no statistically significant microhardness reduction in the bleached enamel (p>0.05). Significant decrease in hardness was observed for enamel slabs bleached with both treatments in the in vitro condition (p<0.05). Regarding the bleaching agents, in situ results showed no difference between HP and WS, while in vitro WS produced the lowest hardness value. It could be concluded that there was no deleterious effect on enamel produced by any of the bleaching protocols used in the in situ model. The reduction of hardness was only observed in vitro.
authors.affiliation: Faculdade Especializada na Área de Saúde do Rio Grande do Sul, Passo Fundo, RS, Brazil.
authors.forename: Sandrina
authors.initials: S
authors.lastname: Henn-Donassollo
authors.affiliation: Faculdade Especializada na Área de Saúde do Rio Grande do Sul, Passo Fundo, RS, Brazil.
authors.forename: Cristiane
authors.initials: C
authors.lastname: Fabris
authors.affiliation: Faculdade Especializada na Área de Saúde do Rio Grande do Sul, Passo Fundo, RS, Brazil.
authors.forename: Morgana
authors.initials: M
authors.lastname: Gagiolla
authors.affiliation: Faculdade Especializada na Área de Saúde do Rio Grande do Sul, Passo Fundo, RS, Brazil.
authors.forename: Ícaro
authors.initials: Í
authors.lastname: Kerber
authors.affiliation: Faculdade Especializada na Área de Saúde do Rio Grande do Sul, Passo Fundo, RS, Brazil.
authors.forename: Vinícius
authors.initials: V
authors.lastname: Caetano
authors.affiliation: Faculdade Especializada na Área de Saúde do Rio Grande do Sul, Passo Fundo, RS, Brazil.
authors.forename: Vitor
authors.initials: V
authors.lastname: Carboni
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Mabel Miluska Suca
authors.initials: MM
authors.lastname: Salas
authors.affiliation: Faculdade Especializada na Área de Saúde do Rio Grande do Sul, Passo Fundo, RS, Brazil.
authors.forename: Tiago Aurélio
authors.initials: TA
authors.lastname: Donassollo
authors.affiliation: Universidade Federal de Pelotas, Pelotas, RS, Brazil.
authors.forename: Flávio Fernando
authors.initials: FF
authors.lastname: Demarco
mesh_terms: D003743:Dental Enamel; D006244:Hardness; D006801:Humans; D066298:In Vitro Techniques; D014073:Tooth Bleaching