Few reports have addressed the effects of diode laser irradiation at 980 nm on the morphology and fracture resistance of dentine. The purpose of this study is to evaluate the effects of 980-nm diode laser on the ultrastructure and fracture resistance of root dentine. The roots of 90 extracted canine teeth were divided into three groups according to the type of irrigating solution (water, NaOCl, and NaOCl/EDTA) and subdivided into three subgroups (n = 10) according to the amount of laser irradiation (without irradiation, 1.5 W/100 Hz and 3.0 W/100 Hz). The roots were filled with an epoxy resin-based sealer and gutta-percha and then subjected to a fracture resistance test. Data were analyzed by ANOVA and the Tukey test (p < 0.05). Additionally, 18 canine teeth were prepared using the same irrigation/irradiation protocols and evaluated by scanning electron microscopy (SEM). The SEM showed greater changes when the laser power increased, and the changes also varied according to the irrigating solution. A modified smear layer was observed in specimens that were treated with water and then laser-irradiated. The laser treatment did not alter the fracture resistance of roots treated with 1.5 W/100 Hz (246.3 ± 29.5 N) and 3.0 W/100 Hz (215.3 ± 25.1 N) laser power. The roots treated with NaOCl were more susceptible to fracture (199.4 ± 15.1 N) than those irrigated with water (254.2 ± 23.0 N) (p < 0.05). The 980-nm diode laser altered the morphology of the dentine but did not affect the fracture resistance of the roots.
This study evaluated the effect of 980-nm diode laser on apical microleakage and intraradicular dentin morphology. Roots of 110 mandibular incisors were used in the study: 92 for microleakage test and 18 for scanning electron microscopy (SEM). Roots were randomly assigned to 3 groups according to the irrigating solution (water, NaOCl and NaOCl/EDTA) and were divided into 3 subgroups according to the laser irradiation protocol (without irradiation, irradiated at 1.5 W and irradiated at 3.0 W). Two specimens of each subgroup were prepared for SEM. The remaining roots were filled with AH Plus and gutta-percha. Apical leakage was assessed by ink penetration and data were analyzed statistically by ANOVA and Tukey-Krammer test (α=0.05). SEM analysis showed intensification of changes with increase of laser power as well as variations according to the irrigating solution. Modified smear layer was observed in specimens treated with water and irradiated with laser. Roots irrigated with NaOCl/EDTA had lower levels of infiltration (0.17 ± 0.18 mm) differing significantly (p<0.05) from those of roots irrigated with water (0.34 ± 0.30 mm), but similar (p>0.05) to those irrigated with NaOCl (0.28 ± 0.29 mm). Non-irradiated roots had lower levels of infiltration (0.10 ± 0.14 mm), differing (p<0.05) from those irradiated at 1.5 W (0.32 ± 0.22 mm) and 3.0 W (0.37 ± 0.32 mm). The 980 nm diode laser modified dentin morphology and increased apical microleakage.
ResumoIntrodução: O hipoclorito de sódio é a substância química auxiliar do tratamento endodôntico mais utilizada devido à sua ação antimicrobiana e à sua capacidade de dissolver matéria orgânica. Objetivo: O objetivo do presente estudo foi comparar a velocidade de dissolução de fragmentos de tecido pulpar bovino em diferentes concentrações de hipoclorito de sódio. Material e método: Fragmentos de tecido pulpar bovino, com peso determinado, foram imersos em 20 mL de hipoclorito de sódio, em frascos de Becker colocados em uma incubadora/agitadora. Foram testadas as concentrações de 1%, 2,5% e 5%, com pH 11, a 36°C. As amostras foram avaliadas visualmente durante a agitação, com auxílio de lupa, até sua completa dissolução. A velocidade de dissolução de cada fragmento foi determinada em miligramas por minuto e a velocidade média de cada grupo, analisada pelos métodos estatísticos de Kruskal-Wallis e Dunn's Multiple. Resultado: Houve diferença estatisticamente significante entre a concentração de 1%, que apresentou a menor velocidade, e as demais. Conclusão: A velocidade de dissolução do hipoclorito de sódio, nas concentrações testadas, se torna mais rápida com o aumento da concentração.Descritores: Hipoclorito de sódio; dissolução; polpa dentária. AbstractIntroduction: sodium hypochlorite is the most used auxiliary chemical substance in endodontic treatment due to its antimicrobial action and its ability to dissolve organic matter. Objective: the objective of the present study was to compare the dissolution speed of bovine pulp tissue fragments in different concentrations of sodium hypochlorite. Material and method: bovine pulp tissue fragments, with determined weight, were immersed in Becker bottles filled with 20 ml of sodium hypochlorite and placed in an incubator/stirrer. Concentrations of 1%, 2.5% and 5%, with pH of 11, at 36°C. Each sample was evaluated visually during the stirring, with the aid of magnifying glass, until its complete dissolution. The speed of dissolution of each fragment was determined in milligrams per minute and by the average speed of each group was analyzed by Kruskal-Wallis and Dunn's Multiple statistical methods. Result: There were statistically significant differences between the concentration of 1%, with the lowest speed, and others. Conclusion: The dissolution speed of sodium hypochlorite of tested concentrations, becomes faster with the increasing of the concentration.Descriptors: Sodium hypochlorite; dissolution; dental pulp.
The aim of this in vitro study was to evaluate the tensile strength of glass fiber posts submitted to different surface treatments. Forty-eight maxillary canines had their crowns sectioned and root canals endodontically treated. The roots were embedded in acrylic resin and distributed into 3 groups according to the surface treatment: Group I: the posts were treated with silane agent for 30 s and adhesive; Group II: the posts were cleaned with alcohol before treatment with silane agent and adhesive; Group III: the posts were submitted to conditioning with 37% phosphoric acid for 30 s before treatment with silane agent and adhesive. Each group was divided into 2 subgroups for adhesive polymerization or not before insertion into the canal: A - adhesive was not light cured and B - adhesive was light cured. All posts were cemented with Panavia F and the samples were subjected to tensile strength test in a universal testing machine at crosshead speed of 1 mm/min. Data were submitted to one-way ANOVA and Tukey's test at 5% significance level. There was statistically significant difference (p<0.01) only between group GIII-B and groups GI-A and GI-B. No significant difference was found among the other groups (p>0.05). It was concluded that the products used for cleaning the posts influenced the retention regardless of adhesive light curing.
Purpose: Dental fusion is defined as the union of two dental germs at some stage of their development. The aim of this article is to report the endodontic treatment of two clinical cases of dental fusion. Case description: In the first case, the patient was referred by an orthodontist for endodontic treatment of tooth 12, which was fused to 13. Surgical separation and later replacement of the involved elements in the dental arch was indicated. In the second case, the patient sought dental attendance due to spontaneous pain. In the radiographic exam, gemination in tooth 11 and fusion of 21 with a supernumerary tooth was observed. The fused teeth were endodontically treated, and patients were referred to other dental specialties to reestablish esthetics and function. Conclusion: The dentist must be able to diagnose, differentiate and treat these dental anomalies adequately, with the goal of maintaining patients' oral health.
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