In situ effect of dentifrices associated to CO2 laser in the permeability of eroded root dentin.

OBJECTIVE: The aim of this study was to evaluate, through a crossover 2×2 in situ trial, the effect of a desensitizing dentifrice associated with CO2 laser irradiation to control the permeability of eroded root dentin. BACKGROUND DATA: Facing the increased prevalence of erosive lesion and the need for preventive means to control painful symptoms related to them. METHODS: Eighty slabs of bovine root dentin were subjected to initial erosive challenge (citric acid 0.3%, 2 h), followed by a remineralizing period in artificial saliva (24 h). Specimens were then divided according to dentin treatment: desensitizing dentifrice, desensitizing dentifrice+CO2 laser, fluoride anticavity dentifrice. and fluoride anticavity dentifrice+CO2 laser. After a 2-day lead-in period, 10 volunteers wore an intraoral palatal appliance containing four root dentin slabs, in two phases of 5 days each. During the intraoral phase, one side of the appliance was immersed in 0.3% citric acid, and the opposite side was immersed in deionized water, four times a day. One hour after the immersions, all specimens were brushed with dentifrice slurry provided by the researcher. After a 7-day washout period, volunteers were crossed over on the different dentifrice group. Each phase having been completed, the specimens were evaluated for permeability through an optical microscope. RESULTS: Data were analyzed using ANOVA and no significant difference (p=0.272) was found between the surface treatments performed on bovine root dentin. CONCLUSIONS: It can be concluded that fluoride anticavity or desensitizing dentifrice, regardless of the association with the CO2 laser irradiation, was able to control the permeability of eroded root dentin.

Estudo da variação da permeabilidade, limpeza e contaminação do sistema de canais radiculares, após o preparo químico-cirúrgico e aplicação de laser de alta intensidade / Study of the variation of permeability, cleaning and contamination of the root canal system after preparation and application of high-intensity

A importância do aumento da permeabilidade e da limpeza da dentina radicular está ligada à melhora da sanificação e obturação do sistema de canais radiculares...

The permeability increasing and the cleanliness of root dentin walls are important to improve the sanitization and root canal filling. Thus, this study aimed to evaluate the variations of root dentin permebility of human teeth, after endodontic preparation followed by Er:YAG and Nd:YAG laser irradiation, using free Technetium-99m radioisotope (99mTc) as tracer. Additionally, SEM images were analyzed to evaluate the cleanliness of dentin walls and possible bacterial adhesion after Enterococcus faecalis inoculation...

Avaliaçäo dos efeitos da irradiaçäo laser, utilizando Nd: YAG, CO² e argônico no selamento dentinário e marginal de obturaçöes retrógradas / Evaluation of laser irradiation effects with the use of Nd: YAG, CO² and Argon regarding dentin and marginal sealing of retrograde fillings

Baseado na necessidade da reavaliaçäo de procedimentos clínicos empregando novas técnicas e equipamentos, esse experimento tem por objetivo observar os efeitos da irradiaçäo laser sobre a permeabilidade dentinária e marginal da superfície apical de dentes apicectomizados e retroobturados. Caninos permanentes, extraídos, tratados endodonticamente, tiveram os três milímetros finais das raízes seccionados, obedecendo o angulo de 180º onde foram preparadas cavidades para as obturaçöes retrógadas. os espécimes foram divididos em vinte e um grupos experimentais obedecendo aos seguintes critérios: tipo de material retroobturador - amálgama de prata, ionômero de vidro e resina fotopolimerizável - tipo de laser - Nd: YAG, CO² e Argônio - e momento da irradiaçäo - antes ou depois da retroobturaçäo...

A possible mechanism of acquired acid resistance of human dental enamel by laser irradiation.

A possible mechanism of acquired acid resistance of lased enamel was proposed on the basis of the investigations of optical properties, compositional and structural changes and permeability of lased and unlased human dental enamel. Lased enamel showed a high positive birefringence, suggesting the formation of 'microspaces' in enamel. No new products were found, though a decrease of lattice strain and a slight a-axis contraction were recognized in lased enamel compared with unlased enamel. The contents of water, carbonate and organic substances were reduced in lased enamel. Gradual changes of birefringence were observed in lased enamel during treatment with acid solutions, and this change was attributed to mineralization of the microspaces. The ions released by an acid decalcification would be trapped in the microspaces in lased enamel, whereas such ions diffuse to the surrounding solution in unlased enamel.

Effect of X-ray irradiation on the permeability of bovine dental enamel.

To estimate permeability properties of bovine dental enamel, complex impedance measurements and radioisotope diffusion experiments were carried out before and after X-ray irradiation (single dose, 72 Gy) of enamel specimens. Neither impedance measurements nor diffusion experiments showed significant changes in permeability.