Evaluation of the bleached human enamel by Scanning Electron Microscopy

Abstract

ince bleaching has become a popular procedure, the effect of peroxides on dental hard tissues is of great interest in research. Purpose: The aim of this in vitro study was to perform a qualitative analysis of the human enamel after the application of in-office bleaching agents, using Scanning Electron Microscopy (SEM). Materials and Methods: Twenty intact human third molars extracted for orthodontic reasons were randomly divided into four groups (n=5) treated as follows: G1-storage in artificial saliva (control group); G2-four 30-minute applications of 35% carbamide peroxide (total exposure: 2h); G3-four 2-hour exposures to 35% carbamide peroxide (total exposure: 8h); G4-two applications of 35% hydrogen peroxide, which was light-activated with halogen lamp at 700mW/cm 2 during 7min and remained in contact with enamel for 20min (total exposure: 40min). All bleaching treatments adopted in this study followed the application protocols advised by manufacturers. Evaluation of groups submitted to 35% carbamide peroxide was carried out after two time intervals (30 minutes and 2 hours per session), following the extreme situations recommended by the manufacturer. Specimens were prepared for SEM analysis performing gold sputter coating under vacuum and were examined using 15kV at 500x and 2000x magnification. Results: Morphological alterations on the enamel surface were similarly detected after bleaching with either 35% carbamide peroxide or 35% hydrogen peroxide. Surface porosities were characteristic of an erosive process that took place on human enamel. Depression areas, including the formation of craters, and exposure of enamel rods could also be detected. Conclusion: Bleaching effects on enamel morphology were randomly distributed throughout enamel surface and various degrees of enamel damage could be noticed. Clinical significance: In-office bleaching materials may adversely affect enamel morphology and therefore should be used with caution. Uniterms: Hydrogen peroxide; Carbamide peroxide; Tooth bleaching.esde o aumento da popularidade de tratamentos clareadores, o interesse em se pesquisar os efeitos dos peróxidos nos tecidos dentais duros é crescente. Proposta: O objetivo deste trabalho foi conduzir uma análise qualitativa in vitro do esmalte dental humano após clareamento com agentes para consultório, por meio de Microscopia Eletrônica de Varredura (MEV). Material e métodos: Foram utilizados 20 terceiros molares humanos hígidos, extraídos por motivos ortodônticos, sendo aleatoriamente divididos em 4 grupos (n=5) e tratados da seguinte forma: G1-armazenamento em saliva artificial (grupo controle); G2-4 aplicações de peróxido de carbamida a 35% por 30 min (tempo total de aplicação: 2h); G3-4 aplicações de peróxido de carbamida a 35% por 2 h (tempo total de aplicação: 8h); G4-2 aplicações de peróxido de hidrogênio a 35%, que foi foto-ativado com lâmpada halógena a 700mW/cm 2 por 7 min e mantido em contato com o dente durante 20 min (tempo total de aplicação: 40min). A avaliação dos grupos submetidos ao clareamento ...

Correlation between pH and surface structural changes on human enamel submitted to different tooth whitening agents

“…However, its potential of remineralization is not equivalent to the natural saliva in vivo, and fluoride ions in the oral cavity are essential to the balance of the demineralization process. [12] SEM images showed the dissolution of enamel organic layer (G 2 , G 3 and G 4 ), however, there was no loss of the non-prismatic layer of enamel surface, in discordance with Markovic et al, [13] who reported a dissolution of the nonprismatic layer and exposure of prisms after long exposure to agents with high percentage of hydrogen peroxide. The most severe effect of 38% hydrogen peroxide observed in this experiment resulted from the keeping of the samples in distilled water; [13] the effects of 38% hydrogen peroxide in our samples were probably mitigated by immersion in artificial saliva.…”

“…As well as Oltu and Gurgan, [7] Pinto et al, [3] Efeoglu et al, [1] Miranda et al, [12] Faraoni-Romano et al, [10] artificial saliva was used in this study (G 1 ; pH=7.0) to simulate mouth conditions. However, its potential of remineralization is not equivalent to the natural saliva in vivo, and fluoride ions in the oral cavity are essential to the balance of the demineralization process.…”

“…This fact is probably attributed to the short exposure time to the bleaching gel (3 applications of 15 min) recommended by the manufacturer and attested by the methodology applied in this experiment, as well as to the neutralizing buffering effect of artificial saliva. [1,3,7,10,12] …”

Influence of Standard Load Micro- and Nanopatterned in Surface Roughness of bleached Teeth and submitted to Different Surface Treatments

“…However, the potential for remineralization is equivalent to the in vivo natural saliva, and fluoride ions in the oral cavity are essential for the balance in the demineralization-remineralization process. 12 The most severe effect of hydrogen peroxide 38% was due to the storage of specimens in distilled water; the effects of hydrogen peroxide 38% in our specimens were probably softened by immersion in artificial saliva.…”

Estudo Microscópico da Prevenção da Desmineralização do Esmalte Dentário Durante Tratamento Ortodôntico Utilizando Selante de Fóssulas e Fissuras

“…A erosão do esmalte seria uma conseqüência ao aumento da porosidade e deposição de precipitado. Depressões com formação de crateras, remoção da camada aprismática e exposição dos prismas de esmalte também podem ser detectados 37 . Ao serem observadas as amostras dos dentes do GIII (controle) podem-se constatar severas alterações que são significativas com grande número de crateras de diferentes profundidades distribuídas em meio a áreas de perda da camada superficial do esmalte.…”