Refrescos ácidos: dissolução do esmalte

Introduction: erosion is the superficial loss of enamel caused by chemical process do not involve bacterias but extrinsic factors as the high consumption of low pH drinks.    Aim: evaluate the enamel superficial roughness of the bovine teeth after the contact of acid solutions.   Material and methods: lemonade (group 1), artificial juice in powder with lemon flavor (group 2), and a light soft drink made of cola and lemon (group 3), evaluate the enamel superficial roughness of the bovine after action of solutions.   Results: the roughness average was: GI (0,0120), GII (0,3215), GIII (0,0275).   Conclusion: the beverage’s effects and the time were statistically significant, GII showed the biggest superficial roughness when compared with GI and GIII.Introdução: erosão é a perda superficial do esmalte causado por processos químicos que não envolvem bactérias, mas fatores extrínsecos como o alto consumo de bebidas que possuem pH muito baixo. Objetivo: avaliação da rugosidade superficial do esmalte de dentes bovinos após a ação de bebidas ácidas. Material e métodos: as amostras foram imersas nas seguintes soluções: GI limonada, GII refresco artificial em pó sabor limão e GIII refrigerante light a base de cola contendo limão, verificando a rugosidade superficial do esmalte após a imersão. Resultados: a média da rugosidade foi GI (0,0120), GII (0,3215), GIII (0,0275).  Conclusão: todas as bebidas testadas interferiram na rugosidade do esmalte; o suco em pó light causou o maior dano ao esmalte; o tempo de exposição do esmalte as bebidas, aumentou os valores da rugosidade

Avaliação in vitro da microdureza superficial do esmalte bovino exposto a soluções ácidas, após receber ou não, clareamento com peróxido de hidrogênio a 35%

Erosão é a perda superficial do esmalte dentário causada por processos químicos que não envolvem bactérias. Alguns fatores intrínsecos e extrínsecos como a presença de substâncias ácidas na cavidade bucal, promovem uma redução do pH do meio, aumentando a erosão ácida. Assim, o objetivo deste estudo foi avaliar a microdureza do esmalte de dentes bovinos clareados e não clareados com peróxido de hidrogênio a 35 %, após a ação de: refrigerante a base de cola, suco artificial em pó contendo citrato de sódio e ácido clorídrico. Os corpos de prova foram divididos em dois grupos, onde 45 amostras de um dos grupos receberam a ação do agente clareador uma vez por semana durante duas semanas. Após este período, as amostras de cada grupo inicial foi dividido em 3 grupos com 15 amostras cada, as quais foram imersas nas soluções ácidas diariamente por 5 minutos e permanecendo 23 horas e 55 minutos em saliva artificial. O experimento foi realizado por 21 dias e as leituras de microdureza de cada corpo de prova foi realizada semanalmente. Os dados obtidos segundo as variáveis: tempo, substância ácida e condição do substrato (esmalte clareado ou não) foram submetidos aos testes estatísticos: Anova e Tukey. Concluiuse que todas as soluções ácidas testadas interferiram com a microdureza do esmalte. Dentes clareados foram os mais susceptíveis aos efeitos erosivos das soluções ácidas. O ácido clorídrico causou o maior dano ao esmalte dentário e o tempo de exposição do esmalte às soluções ácidas influiu diretamente na quantidade de desmineralização.Acid erosion is the loss of enamel surface caused by chemical processes that do not involve bacteria. Some intrinsic and extrinsic factors, as the presence of acid substances in the oral cavity, promote a pH reduction, increasing acid erosion. Thus, the aim of this study was to evaluate the microhardness of bleaching and not bleaching bovine enamel after the effect of a cola drink, an artificial powder juice and hydrochloric acid. The data obtained by the variables: time, acid solution and condition of substrate (enamel whitening or not whitening) were subjected to statistical tests: ANOVA and Tukey. It was concluded that all acid solutions tested interfered with the enamel microhardness. Hydrochloric acid caused the biggest damage to enamel and the time of enamel exposure to acid solutions directly influenced the demineralization amount. Whitened enamel was more affected by acid erosion. -Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES

In vitro evaluation of the microhardness of bovine enamel exposed to acid solutions after bleaching

Acid erosion is a superficial loss of enamel caused by chemical processes that do not involve bacteria. Intrinsic and extrinsic factors, such as the presence of acid substances in the oral cavity, may cause a pH reduction, thus potentially increasing acid erosion. The aim of this study was to evaluate the microhardness of bleached and unbleached bovine enamel after immersion in a soda beverage, artificial powder juice and hydrochloric acid. The results obtained for the variables of exposure time, acid solution and substrate condition (bleached or unbleached enamel) were statistically analyzed by the ANOVA and Tukey tests. It was concluded that a decrease in microhardness renders dental structures more susceptible to erosion and mineral loss, and that teeth left unbleached show higher values of microhardness compared to bleached teeth

In vitro evaluation of the microhardness of bovine enamel exposed to acid solutions after bleaching

Acid erosion is a superficial loss of enamel caused by chemical processes that do not involve bacteria. Intrinsic and extrinsic factors, such as the presence of acid substances in the oral cavity, may cause a pH reduction, thus potentially increasing acid erosion. The aim of this study was to evaluate the microhardness of bleached and unbleached bovine enamel after immersion in a soda beverage, artificial powder juice and hydrochloric acid. The results obtained for the variables of exposure time, acid solution and substrate condition (bleached or unbleached enamel) were statistically analyzed by the ANOVA and Tukey tests. It was concluded that a decrease in microhardness renders dental structures more susceptible to erosion and mineral loss, and that teeth left unbleached show higher values of microhardness compared to bleached teeth

Smear layer removal capacity of disinfectant solutions used with and without EDTA for the irrigation of canals: a SEM study

The purpose of this study was to carry out a scanning electron microscopic (SEM) analysis of the cleaning qualities and smear layer removal from root canal walls, instrumented and irrigated with 2.5% NaOCl, 2.0% chlorhexidine and saline solutions. Fifty extracted teeth were used in this study. All teeth were radiographed to determine the existence of a single canal. The crowns were cut at the cervical limit and the root canals were instrumented with K-type files up to size 45. During root canal preparation, irrigations were made with the different solutions being evaluated: Group 1: 2.5% NaOCl (10 roots); Group 2: 2.5% NaOCl and 17% EDTA for 2 minute (10 roots); Group 3: 2.0% chlorhexidine (10 roots); Group 4: 2.0% chlorhexidine and 17% EDTA for 2 minutes (10 roots); Group 5: saline solution (5 roots); Group 6: saline solution and 17% EDTA for 2 minutes (5 roots). After instrumentation, the canals were irrigated with each one of the solutions and the roots were cut in the buccolingual direction for SEM analysis, at the cervical, middle and apical thirds, to ascertain the presence or absence of smear layer and debris. SEM analysis was performed by three calibrated examiners and scores were submitted to Kruskal-Wallis test at the significance level of p = 5%. Results showed that the use of 17% EDTA decreased the smear layer significantly (p < 0.05) for all evaluated solutions in all thirds. When EDTA was not used, a significantly higher quantity of smear layer on the apical third was observed only in the NaOCl groups. The use of 17% EDTA was significant for debris removal except for the chlorhexidine groups. The following conclusion could be drawn: the use of 17% EDTA was necessary to enhance cleanness of the root canals

Bond Strength of Repaired Composite Resin Restorations

Purpose: To evaluate the bond strength of direct composite resins and composite repairs, using 3 different commercial brands - GI: Palfique Estelite Ó (Tokuyama), GII: Filtek Z350 (3M/ESPE) and GIII: Te Econon (Ivoclar/Vivadent) - and the use of AdperTM Single Bond 2 (3M/ESPE) adhesive system at the base/repair interface. Method: Thirty conic bases (5 mm x 5 mm x 3 mm) of each commercial brand of composite resin were fabricated. All bases of each group were submitted to a thermocycling regimen of 20,000 cycles (5ºC to 55ºC ± 2ºC, for 30 s). The bases of each group were randomly assigned to 3 sub-groups, in which a combination of the commercial brands was performed for the repairs. The specimens were stored in distilled water at 37°C during 7 days and were thereafter tested in tensile strength in a universal testing machine (EMIC - MEM 2000) with 500 kgf load cell running at a crosshead speed of 1.0 mm/min until fracture. Data in MPa were submitted to ANOVA and Tukey’s test (5%).Results: The following results were found: GI: Palfique Estelite Ó (11.22±4.00 MPa), Te Econom (12.03±3.47 MPa) and Filtek Z350 (10.66±2.89 MPa); GII: Palfique Estelite Ó (8.88±2.04 MPa), Te Econom (7.77±1.64 MPa) and Filtek Z350 (10.50±6.14 MPa); and GIII: Palfique Estelite Ó (8.41±2.50 MPa), Te Econom (12.33±3.18 MPa) and Z350 (11.73±3.54 MPa).Conclusion: The bond strengths at the interface of the different composite resins submitted to repair were statistically similar regardless of the commercial brand