Comparative analysis of the effects of ozone and ultrasound on Streptococcus mutans

Streptococcus mutans is one of the principal pathogens of the human oral habitat, being one of the principal etiological agents of carious lesions. Ozone is a powerful oxidant, it has the ability to inactivate microorganisms in general, and ultrasound is an acoustic system generated through a piezoelectric crystal that also presents microbicidal effects. In the present study, a comparative analysis was made of the damage caused to Streptococcus mutans in vitro by ultrasound and ozone, through scanning electron microscopy (SEM) and atomic force microscopy (AF) analysis. In addition, flow cytometry was used to determine microbial viability and the formation of Reactive Oxygen Species (ROS) after the application of different techniques. The data obtained by means of micro- scopic analysis reveal that both ozone and ultrasound produce morphological alterations in bacteria, which become rod-shaped organisms. In addition to this deformation, on the microbial surface it was possible to identify crater-like impressions. In contrast, the irregularity of protuber- ances on the surface of the microbial wall was only detected when ozone was employed. Regarding the formation of ROS, it was observed that that ozone induces a significant growth (p < .05) of these molecules, while ultrasound does not present this effect. Ozone and ultrasound present micro- bicidal effects, however, ozone is more efficient.

Analysis of damage on the Streptococcus mutans immersed in ozonated water: preliminary study for application as mouth rinse

Ozonated water has been demonstrated to induce significant results in terms of the elimination ofmicroorganisms. The present study assessed the damage toStreptococcusmutansafter exposureto ozonated water; the ozone generator was adjusted to provide an outlet concentration of60 mg/L, the samples were submitted to different ozonation times 1, 2, 4, 6, and 10 mi. Scanningelectron microscopy and atomic force images were obtained to identify damage to the bacteria,followed by reactive oxygen species (ROS) evaluation and microbial viability. The results showed asignificant reduction in viability and the images evidenced the generation of gaps on themicrobial wall and surface layer alterations. Ozone can induce significant damage toS.mutans,thus suggesting that the use of ozonated water to prevent carious lesion formation is extremelypromising.

Analysis of damage on the Streptococcus mutans immersed in ozonated water: preliminary study for application as mouth rinse

Ozonated water has been demonstrated to induce significant results in terms of the elimination ofmicroorganisms. The present study assessed the damage toStreptococcusmutansafter exposureto ozonated water; the ozone generator was adjusted to provide an outlet concentration of60 mg/L, the samples were submitted to different ozonation times 1, 2, 4, 6, and 10 mi. Scanningelectron microscopy and atomic force images were obtained to identify damage to the bacteria,followed by reactive oxygen species (ROS) evaluation and microbial viability. The results showed asignificant reduction in viability and the images evidenced the generation of gaps on themicrobial wall and surface layer alterations. Ozone can induce significant damage toS.mutans,thus suggesting that the use of ozonated water to prevent carious lesion formation is extremelypromising.

Effect of Nd:YAG laser on the solvent evaporation of adhesive systems.

OBJECTIVE: This study evaluated the influence of Nd:YAG laser on the evaporation degree (ED) of the solvent components in total-etch and self-etch adhesives. MATERIALS AND METHODS: The ED of Gluma Comfort Bond (Heraeus-Kulzer) one-step self-etch adhesive, and Adper Single Bond 2 (3M ESPE), and XP Bond (Dentsply) total-etch adhesives was determined by weight alterations using two techniques: Control--spontaneous evaporation of the solvent for 5 min; Experimental--Nd:YAG laser irradiation for 1 min, followed by spontaneous evaporation for 4 min. The weight loss due to evaporation of the volatile components was measured at baseline and after 10 s, 20 s, 30 s, 40 s, 50 s, 60 s, 70 s, 80 s, 90 s, 100 s, 110 s, 2 min, 3 min, 4 min, and 5 min. RESULTS: Evaporation of solvent components significantly increased with Nd:YAG laser irradiation for all adhesives investigated. Gluma Comfort Bond showed significantly higher evaporation of solvent components than Adper Single Bond 2 and XP Bond. All the adhesives lost weight quickly during the first min of Nd:YAG laser irradiation. CONCLUSION: The application of Nd:YAG laser on adhesives before light curing had a significant effect on the evaporation of the solvent components, and the ED of Gluma Comfort Bond one-step self-etch adhesive was significantly higher than with Adper Single Bond 2 and XP Bond total-etch adhesives. CLINICAL RELEVANCE: The use of the Nd:YAG laser on the uncured adhesive technique can promote a greater ED of solvents, optimizing the longevity of the adhesive restorations.

AFM characterization of bovine enamel and dentine after acid-etching.

Teeth are constituted mainly of hydroxyapatite molecules (Ca(10)(PO(4))(6)(OH)(2)), grouped in different microstructural arrangements, depending on the dental layer considered (enamel or dentine). In the present work, these dental microstructural arrangements were characterized by atomic force microscopy. Enamel and dentine samples were cut from freshly extracted bovine incisor teeth. After metallographic polishing, the dental surfaces were etched with lactic acid (113.8 mmol/L, pH 3.3). Three etching times were tested: 1, 3 and 5 min. Atomic force micrographs showed that 1 min of etching time was effective to remove the smear layer, polishing debris and scratches, and display the characteristics of interest for both enamel and dentine. Although the bovine dental enamel rod cross-section presented keyhole-like shape, its measured dimensions (8.8 microm of major axis and 3.7 microm of minor axis) exhibited an insignificant discrepancy from human prisms diameters. Bovine dentinal tubules displayed larger mean diameters (4.0 microm) and a lower density (approximately 17,100 tubules/mm(2)) than human dentine, suggesting that the use of bovine dentine as a substitute for human dentine in resin adhesion investigations should be reconsidered. Apatite nanoparticles presented a mean radius (22-23 nm) considerably smaller than that of human teeth.

Avaliaçäo da rugosidade do esmalte dentário após microabrasäo seguida de diferentes métodos de polimento / Evaluation of roughness of tooth enamel after microabrasion followed by different polishing methods

O propósito da presente pesquisa foi avaliar a rugosidade do esmalte dentário após microabrasäo, seguido de diferentes métodos de polimento. Foram selecionados 60 dentes humanos íntegros, que sofreram três avaliaçöes em rugosímetro Perthometer S8P (Pherten-Mahr, Germany). A primeira foi feita no esmalte íntegro. A segunda, após a microabrasäo, e a terceira avaliaçäo foi feita após os procedimentos de polimento. Os dados obtidos com as avaliaçöes foram analisados estatisticamente. De acordo com os resultados, verificou-se que: o ácido clorídrico a 18 por cento promove mais irregularidades na superfície dental; as técnicas de polimento promoveram alisamento semelhante para as duas concentraçöes ácidas, näo havendo diferença estatisticamente significante entre os métodos; os métodos de polimento empregados proporcionaram maior lisura da superfície do esmalte que em sua condiçäo original

Avaliaçäo da rugosidade superficial de cimentos de ionômero de vidro com diferentes sistemas de acabamento e polimento / Surface roughness evaluation of a glass ionomer with different finishing and polishing systems

Foi realizado um estudo experimental no qual se avaliou a rugosidade superficial de três cimentos de ionômero de vidro após acabamento e polimento com dois sistemas diferentes de polimento, utilizando-se dois tipos de agentes lubrificantes. Os cimentos utilizados foram: Dyract (Dentsply), Vitremer (3M) e Vidrion R (S. S. White). Confeccionaram-se 20 corpos-de-prova (c.p.) de 9 mm de diâmetro e 3 mm de espessura com cada material a partir de tubetes anestésicos. Após uma semana de armazenamento em água a 37ºC, todas as amostras tiveram o mesmo acabamento, realizado com broca de 12 lâminas. O polimento foi realizado da seguinte forma: dos 20 c.p. de cada material, 10 foram polidos com discos Sof-Lex de granulaçäo fina e extrafina (3M), sendo cinco c.p., lubrificados com manteiga de cacau e cinco com ácido poliacrílico em gel; os demais c.p. foram polidos com pontas siliconadas verde e cinza (K. G. Sorensen), sendo cinco lubrificados com manteiga de cacau e cinco com ácido poliacrílico em gel. Mediu-se o parâmetro de rugosidade superficial Ra para todos os c.p., em rugosímetro Perthometer S8P, e, para cada um deles, efetuaram-se cinco mediçöes antes e cinco após o polimento, para efeito de amostragem estatística (600 mediçöes ao total). Aplicou-se aos dados obtidos o método estatístico da análise de variância (ANOVA) e o teste de Tukey, concluindo-se que, quanto ao material restaurador, o Dyract apresentou menor rugosidade se comparado ao Vidrion R e Vitremer; em relaçäo ao polimento, os discos Sof-Lex apresentaram resultados superiores às pontas de silicone e os agentes lubrificantes näo apresentaram diferença significante estatisticamente

Avaliação da infiltração marginal por corante em dentes apicectomizados e recobertos com materiais adesivos após irradiação com laser Nd: YAG / Evaluation of marginal infiltration in teeth apicoectomy and capped with adhesive materials after Nd: YAG laser irradiation

Na tentativa de eliminar a infiltração apical, muitos materiais foram pesquisados como retrobturadores, mas apesar das vantagens e desvantagens de cada um, sabe-se que o material ideal ainda não foi encontrado. Procurando reduzir a infiltração apical, o laser tem sido utilizado para ocluir túbulos dentinários seccionados pela fusão e recristalização da superfície dentinária, apresentando bons resultados. O objetivo deste trabalho foi avaliar a capacidade de selamento apical de quatro materiais odontológicos empregados no recobrimento de ápices radiculares seccionados após a irradiação com laser Nd: YAG. Foram utilizados 45 dentes unirradiculados humanos extraídos, divididos em três grupos com 15 dentes cada. Os canais radiculares foram preparados e obturados com guta-percha e cimento pela técnica da condensação lateral ativa. Os dentes receberam apicectomia e recobrimento da superfície radicular seccionada com sistema adesivo dentinário e resina composta, cimento de ionômero de vidro e compômero, após a irradiação com laser Nd: YAG. Os espécimes foram imersos em corante azul de metileno a 2 por cento durante uma semana a 37ºC e as infiltrações ocorridas foram avaliadas com auxílio de um estereomicroscópio. Pôde-se concluir que, no recobrimento apical após a irradiação com laser, o cimento de ionômero de vidro e o compômero foram equivalentes entre si e significativamente melhores que o sistema adesivo dentinário e resina composta