In vitro study of the effects of Nd:YAG laser irradiation on the apical sealing of endodontic fillings performed with and without dentin plugs.

OBJECTIVE: The aim of this study was to evaluate the effects of Nd:YAG laser irradiation on the apical sealing of root canal fillings with or without a dentin plug. BACKGROUND DATA: Previous studies have shown that Nd:YAG laser irradiation of root canal wall dentin promotes its melting, recrystallization, and therefore a less permeable surface. MATERIALS AND METHODS: Thirty extracted and endodontically treated teeth were divided into three groups. Eight specimens of each group were evaluated by means of quantitative analysis, measuring the marginal apical dye leakage. The remaining two specimens were evaluated by means of qualitative analysis, using the scanning electron microscopy (SEM). For the quantitative analysis, the samples of group I were obturated. In group II, the apical third of the samples were irradiated by the Nd:YAG laser at four exposures of 100 mJ/pulse, 1 W, 10 Hz, 3 sec, and obturated. In group III, an apical dentin plug was condensed and lased using the same parameters of group II, and the root canals were obturated. The samples evaluated by SEM were prepared as those analyzed quantitatively; however, their root canals were not filled. RESULTS: There were statistically significant differences among the groups regarding dye leakage. Group II showed the minor leakage average, followed, in order, by groups I and III. SEM analysis revealed open dentinal tubules in group I; melting and recrystallizing of the apical root dentin in group II; and melting and recrystallizing of a portion of the dentin plug in group III. CONCLUSION: The Nd:YAG laser irradiation of the root canal apical third without the presence of dentin plug significantly improved the quality of the apical sealing under the experimental conditions tested.

Method of preparing inter-mouth protectors as a means of preventing dental trauma.

A method of preparing individualized inter-mouth protectors for patients at risk of dental trauma or inclined to suffer trauma is presented. A totally individualized protector is more efficient for the protection and prevention of dental trauma. Two sessions with the patient were required. We conclude that the method was simple, observing all the necessary requirement for this type of device.

["In vitro" analysis of the dentin permeability of the apical third of the root as a function of changes in auxiliary chemicals used in instrumentation]. / Análise "in vitro" da permeabilidade dentinária radicular do terço apical, tendo como fonte de variação a substância quimica auxiliar da instrumentação.

We analyzed the possible percentage variations of dentinal penetration of the methylene blue solution in the apical third, in human teeth pulled out, after it's preparation, utilizing files type K-Flex, and five auxiliary chemical substances. Results have shown that there is a significant difference among the percentage of the dye penetration and among the auxiliary chemical substances used for the chemical-mechanic preparation. We can also prove true that, for apical region, the Endo PTC was the one that showed the greatest percentage of penetration.