Efeito do ácido clorídrico gasoso no esmalte humano e bovino

Objetivo: Avaliar a ação do ácido clorídrico gasoso sobre o esmalte humano e bovino e comparar o padrão de desmineralização desses substratos expostos ao agente erosivo gasoso. Métodos: Oito espécimes de esmalte bovino e oito de esmalte humano foram obtidos (4 × 4 × 2 mm), metade da superfície foi protegida com resina composta e a outra metade exposta ao ácido clorídrico gasoso (gHCl), pH 2 a 37 °C, por 3 min, 8 vezes ao dia, durante 12 dias, e em intervalos os espécimes foram mantidos em saliva artificial. Os espécimes foram analisados quanto ao perfil de desgaste, rugosidade superficial e microdureza (antes e após a exposição ao ácido). Os dados foram analisados estatisticamente por ANOVA de uma via. Resultados: Os dados não mostraram diferença significativa entre o esmalte bovino e humano para todas as propriedades analisadas – microdureza (98,1 ± 5,2, 96,9 ± 4,8), perfil de desgaste (11,5 ± 2,8, 11,4 ± 3,6) e rugosidade (2,6 ± 0,3, 3,3 ± 0,3), respectivamente. Nas imagens, observou-se que gHCl pode causar erosão do esmalte em ambos os grupos. Conclusão: O ácido clorídrico gasoso causa erosão do esmalte de forma semelhante em bovinos e humanos.Objective: To evaluate the action of gaseous hydrochloric acid on human and bovine enamel and compare the demineralization pattern of these substrates exposed to the gaseous erosive agent. Methods: Eight bovine enamel and eight human enamel specimens were obtained (4 × 4 × 2 mm), half surface was protected with composite resin and the other half was exposed to gaseous hydrochloric acid (gHCl), pH 2 at 37 °C, for 3 min, 8 times a day, for 12 days, and in intervals the specimens were maintained in artificial saliva. The specimens were analyzed according to wear profile, surface roughness and microhardness (before and after acid exposition). Data were statistically analyzed by one-way ANOVA. Results: Data showed no significant difference between bovine and human enamel for all properties analyzed – microhardness (98.1 ± 5.2, 96.9 ± 4.8), wear profile (11.5 ± 2.8, 11.4 ± 3.6) and roughness (2.6 ± 0.3, 3.3 ± 0.3), respectively. In images, we observed that gHCl could cause enamel erosion in both groups. Conclusion: Gaseous hydrochloric acid causes similar enamel erosion on bovine and humans

Effect of Nd:YAG laser combined with fluoride on the prevention of primary tooth enamel demineralization

Most studies dealing with the caries preventive action of Nd:YAG laser have been done in permanent teeth and studies on primary teeth are still lacking. The aim of this study was to evaluate in vitro the effect of Nd:YAG laser combined or not with fluoride sources on the acid resistance of primary tooth enamel after artificial caries induction by assessing longitudinal microhardness and demineralization depth. Sixty enamel blocks obtained from the buccal/lingual surface of exfoliated human primary molars were coated with nail polish/wax, leaving only a 9 mm² area exposed on the outer enamel surface, and randomly assigned to 6 groups (n=10) according to the type of treatment: C-control (no treatment); APF: 1.23% acidulated phosphate fluoride gel; FV: 5% fluoride varnish; L: Nd:YAG laser 0.5 W/10 Hz in contact mode; APFL: fluoride gel + laser; FVL: fluoride varnish + laser. After treatment, the specimens were subjected to a des-remineralization cycle for induction of artificial caries lesions. Longitudinal microhardness data (%LMC) were analyzed by the Kruskal-Wallis test and demineralization depth data were analyzed by oneway ANOVA and Fisher&#8217;s LSD test (á=0.05). APFL and APF groups presented the lowest percentage of microhardness change (p<0.05). Demineralization depth was smaller in all treated groups compared with the untreated control. In conclusion, Nd:YAG laser combined or not with fluoride gel/varnish was not more effective than fluoride alone to prevent enamel demineralization within the experimental period

Laser managed in the treatment of hypomineralized occlusal defects in teeth enamel affected by molar-incisor hypomineralization: A randomized controlled clinical study / Uso do laser no tratamento dos defeitos oclusais hipomineralizados em esmalte de dentes afetados pela hipomineralização molar-incisivo: estudo clínico controlado randomizado

Background: Nowadays, observed a growing rate of teeth affected by molar incisor hypomineralization (MIH). These teeth can present persistent inflammation of the pulp, increasing the dentin hypersensitivity and consequently, directly affecting the cleaning of the affected tooth and contributing to the progression of caries lesions. Aims: This study aims to compare the use of diode laser (DL) irradiation (970nm) with the application of a glass ionomer-based sealant (GIC) for the most clinically and cost-effective strategy for the management of first permanent molars affected with MIH. Methods: This is a two-arm, parallel-group, patient randomized superiority-controlled trial, children present MIH molars will be selected and treated either with the application of DL or with the application of GIC-based sealants. Baseline and follow-up evaluations will be assessed through clinical examination and analysis of dental impressions that will be carried out of the affected teeth. The outcomes evaluated will be: 1) presence of post-eruptive breakdown and/or atypical dentin caries lesions, 2) retention rate of sealants 3) parent’s satisfaction, 4) children’s hypersensitivity 5) child-self-reported discomfort 6) impact on the quality of life and 7) the incremental cost-effectiveness. Evaluations will be performed by one trained evaluator after one week, and 1, 6, 12, 18, and 24 months. Multilevel statistical analyzes will be conducted to establish the ability of DL treatment compared to sealing, in joining to plausible factors associated with this efficacy. Discussion: We expect that this study contributes to the best scientific proof concerning the most cost-effective treatment for permanent molars affected with MIH

Evaluation of enamel and root dentin surface wear submitted to bleaching treatment: in vitro and in situ

Devido a alterações químico-estruturais causadas pelo clareamento, os substratos dentais poderiam tornar-se mais susceptíveis a perda tecidual, principalmente se expostos a desafios erosivo/abrasivos. Desta forma, o presente estudo teve como objetivos: 1) analisar in vitro, se o esmalte e a radicular dentina clareada com diferentes agentes e concentrações, apresenta uma maior susceptibilidade ao desgaste, quando submetido a ciclos de erosão e abrasão; 2) comparar o efeito da aplicação de um agente clareador a base de peróxido de carbamida a 10% a um placebo no desgaste do esmalte e da dentina radicular, através de um modelo in situ. Os resultados do estudo in vitro mostraram que, independentemente do agente usado, o clareamento não aumentou o desgaste do esmalte frente a episódios erosivo-abrasivos. Na dentina, o desgaste foi dependente do agente clareador aplicado. Baseado no protocolo in situ adotado, o peróxido de carbamida a 10% não causou maior desgaste superficial no esmalte, mas aumentou a perda de tecido dentinário comparado ao placebo. Pode-se concluir que, em termos de desgaste superficial, o esmalte não foi afetado pelo tratamento clareador, enquanto a dentina mostrou-se mais susceptível. Assim, sugerem-se cuidados adicionais na seleção do agente clareador em situações clínicas que apresentam dentina radicular exposta.Due to the chemical and microstructural alterations caused by bleaching, the dental substrates can become more susceptible to tissue loss, mainly if exposed to erosive/abrasive challenges. Therefore, the present study had the following objectives: 1) to analyze in vitro, if enamel and root dentin that had been bleached with different agents and concentrations, were at increased risk of wear when submitted to cycles of erosion and abrasion; 2) to compare the effect of the application of a 10% carbamide peroxide bleaching agent to a placebo on wear of enamel and root dentin, through an in situ model. The results of the in vitro study showed that independent of agent used, the bleaching demonstrated no increase in the wear of enamel when exposed to the erosive-abrasive episodes. In dentin, the wear was dependent on the bleaching agent applied. Based on the in situ protocol adopted, the 10% carbamide peroxide did not cause higher wear on the enamel, but increased the wear of the root dentin compared to the placebo. It could be concluded that in terms of superficial wear, enamel was not affected by bleaching treatment, while dentin showed to be more susceptible. Thus, additional caution is suggested in the choice of the bleaching agent when root dentin is exposed

Evaluation of enamel and root dentin surface wear submitted to bleaching treatment: in vitro and in situ

Devido a alterações químico-estruturais causadas pelo clareamento, os substratos dentais poderiam tornar-se mais susceptíveis a perda tecidual, principalmente se expostos a desafios erosivo/abrasivos. Desta forma, o presente estudo teve como objetivos: 1) analisar in vitro, se o esmalte e a radicular dentina clareada com diferentes agentes e concentrações, apresenta uma maior susceptibilidade ao desgaste, quando submetido a ciclos de erosão e abrasão; 2) comparar o efeito da aplicação de um agente clareador a base de peróxido de carbamida a 10% a um placebo no desgaste do esmalte e da dentina radicular, através de um modelo in situ. Os resultados do estudo in vitro mostraram que, independentemente do agente usado, o clareamento não aumentou o desgaste do esmalte frente a episódios erosivo-abrasivos. Na dentina, o desgaste foi dependente do agente clareador aplicado. Baseado no protocolo in situ adotado, o peróxido de carbamida a 10% não causou maior desgaste superficial no esmalte, mas aumentou a perda de tecido dentinário comparado ao placebo. Pode-se concluir que, em termos de desgaste superficial, o esmalte não foi afetado pelo tratamento clareador, enquanto a dentina mostrou-se mais susceptível. Assim, sugerem-se cuidados adicionais na seleção do agente clareador em situações clínicas que apresentam dentina radicular exposta.Due to the chemical and microstructural alterations caused by bleaching, the dental substrates can become more susceptible to tissue loss, mainly if exposed to erosive/abrasive challenges. Therefore, the present study had the following objectives: 1) to analyze in vitro, if enamel and root dentin that had been bleached with different agents and concentrations, were at increased risk of wear when submitted to cycles of erosion and abrasion; 2) to compare the effect of the application of a 10% carbamide peroxide bleaching agent to a placebo on wear of enamel and root dentin, through an in situ model. The results of the in vitro study showed that independent of agent used, the bleaching demonstrated no increase in the wear of enamel when exposed to the erosive-abrasive episodes. In dentin, the wear was dependent on the bleaching agent applied. Based on the in situ protocol adopted, the 10% carbamide peroxide did not cause higher wear on the enamel, but increased the wear of the root dentin compared to the placebo. It could be concluded that in terms of superficial wear, enamel was not affected by bleaching treatment, while dentin showed to be more susceptible. Thus, additional caution is suggested in the choice of the bleaching agent when root dentin is exposed

Effect of a 10% carbamide peroxide on wear resistance of enamel and dentine: In situ study

Objectives: This triple-blind, 2 x 2 crossover in situ study, was undertaken to verify whether the wear resistance of enamel and root dentine would be affected by bleaching with a 10% carbamide peroxide agent and a placebo agent. Methods: Thirty slabs of each. substrate (2 mm x 3 mm x 2 mm) were selected for each phase, after flattening and polishing procedures and microhardness test. After a 7-day lead-in period, one specimen of each substrate was randomly bonded on the facial surface of each one of 30 subject`s upper second premolars. The volunteers received instructions on how to perform toothbrushing and application of gel in the tray. Fifteen volunteers bleached their maxillary arch with a 10% carbamide peroxide bleaching agent for a 2-week period, while the remainders used a placebo agent. After a 1-week washout period, a new set of enamel and root dentine slabs were bonded to the premolars and volunteers were crossed over to the alternate agent for 14 days. The resistance of enamel and root dentine to wear following bleaching, toothbrushing and intraoral exposure was measured with a profilometer, using reference areas. Results: For enamel, ANOVA did not demonstrate significant difference between wear provided by placebo and bleaching agent (p = 0.3713), but higher wear depth was observed for bleached root dentine (p = 0.0346). Conclusions: While overnight bleaching caused no alteration in wear resistance of enamel, root dentine showed increased tissue loss. (C) 2008 Elsevier Ltd. All rights reserved.CNPq[477419/2004-6]FAPESP[04/15795-0

Effect of a bleaching agent on abrasion of resin-based restoratives

Purpose: To evaluate the effect of a 10% carbamide peroxide-containing bleaching agent on brushing abrasion of esthetic restorative materials. Methods: Using a randomized complete block design, 150 specimens (n = 15) measuring 3 x 3 x 2 mm were fabricated into acrylic resin cylinders, using one of the restorative materials: a microfilled resin composite (At), a hybrid resin composite (Ch), a flowable resin composite (Wa), a resin-modified glass-ionomer cement (Fj) and a polyacid-modified resin composite (Dy). The bleaching agent or artificial saliva (control) was applied for 2 hours/day. After that, 120 brushing strokes were simulated automatically and the samples were kept in artificial saliva. Such bleaching/brushing cycle was performed daily for 21 days. Wear depth was assessed using profilometry. Results: Bleaching did not show significant effect on wear depth. There was a significant difference among the restorative materials. Tukey`s test showed that (Al=Ch) < (Wa) < (Fj) and that Dy was only different from Fj. (Am J Dent 2009;22:171-174).The State of Sao Paulo Research Foundation (FAPESP)[01/07035-7

Bleaching Agents with Varying Concentrations of Carbamide and/or Hydrogen Peroxides: Effect on Dental Microhardness and Roughness

To evaluate the effect of low and highly concentrated bleaching agents on microhardness and surface roughness of bovine enamel and root dentin. According to a randomized complete block design, 100 specimens of each substrate were assigned into five groups to be treated with bleaching agents containing carbamide peroxide (CP) at 10% (CP10); hydrogen peroxide (HP) at 7.5% (HP7.5) or 38% (HP38), or the combination of 18% of HP and 22% of CP (HP18/CP22), for 3 weeks. The control group was left untreated. Specimens were immersed in artificial saliva between bleaching treatments. Knoop surface microhardness (SMH) and average surface roughness (Ra) were measured at baseline and post-bleaching conditions. For enamel, there were differences between bleaching treatments for both SMH and Ra measurements (p = 0.4009 and p = 0.7650, respectively). SMH significantly increased (p < 0.0001), whereas Ra decreased (p = 0.0207) from baseline to post-bleaching condition. For root dentin, the group treated with CP10 exhibited the significantly highest SMH value differing from those groups bleached with HP18/CP22, HP7.5, which did not differ from each other. Application of HP38 resulted in intermediate SMH values. No significant differences were found for Ra (p = 0.5975). Comparing the baseline and post-bleaching conditions, a decrease was observed in SMH (p < 0.0001) and an increase in Ra (p = 0.0063). Bleaching agents with varying concentrations of CP and/or HP are capable of causing mineral loss in root dentin. Enamel does not perform in such bleaching agent-dependent fashion when one considers either hardness or surface roughness evaluations. Bleaching did not alter the enamel microhardness and surface roughness, but in root dentin, microhardness seems to be dependent on the bleaching agent used.FAPESP Sao Paulo State Research Foundation[03/03802-9]FAPESP Sao Paulo State Research Foundation[04/07613-9