Resumo Introdução Os dentes tratados endodonticamente são mais suscetíveis à fratura radicular do que os dentes vitais. Para reduzir o risco de fratura, indica-se o uso de coroas e retentores intrarradiculares. No entanto, ainda não está clara a resistência dessas estruturas a fraturas. Objetivo Analisar o comportamento de copings de coroa metalocerâmica cimentados com dois tipos de retentores intrarradiculares sob tensão de tração. Material e método Dezesseis copings de coroa metalocerâmica cimentados com cimento de fosfato de zinco para núcleos e pinos de metal fundido (grupo 1, n= 8) ou com cimento resinoso autoadesivo para núcleos de resina composta com pinos de fibra de vidro (grupo 2, n= 8) foram submetidos a testes de tração após tratamento endodôntico e preparo padronizado. Houve falha quando o coping da coroa e/ou a estrutura pino-núcleo se quebrou e/ou se soltou. Resultado No grupo 1, após a aplicação de uma carga de tração média de 46,83 N, 7 copings e núcleos metálicos se separaram completamente, enquanto em 1 espécime o coping se soltou do núcleo metálico. No grupo 2, uma carga de tração média de 127,68 N resultou em fratura do pino de fibra de vidro, e em 1 caso toda a estrutura coroa-pino-núcleo se soltou. A resistência à tração foi significativamente diferente entre os dois grupos ( P= 0,0085). Conclusão Nossos achados sugerem que copings de coroa metalocerâmica cimentados com cimento resinoso autoadesivo apresentam forte adesão aos núcleos de resina composta associados aos pinos de fibra de vidro, proporcionando uma alternativa segura ao uso de retentores de metal fundido.

Abstract Introduction Endodontically treated teeth are more susceptible to root fracture than vital teeth. In order to reduce the risk of fracture, the use of intra-radicular posts and crowns is indicated. However, their own fracture resistance remains unclear. Objective To analyze the behavior of metal-ceramic crown copings cemented to two types of intra-radicular posts under tensile stress. Material and method Sixteen metal-ceramic crown copings cemented with zinc phosphate cement to cast metal posts and cores (group 1, n = 8) or with self-adhesive resin cement to glass-fiber posts rebased with composite resin (group 2, n = 8) were subjected to tensile testing after endodontic treatment and standardized preparation. Failure occurred when the crown coping and/or post-core assembly fractured and/or detached. Result In group 1, after the application of a mean tensile load of 46.83 N, 7 crown copings and metal cores separated as a whole, while in 1 specimen the coping detached from the metal core. In group 2, a mean tensile load of 127.68 N resulted in glass-fiber post fracture, and in 1 case the entire crown-post-core assembly was detached. Tensile strength differed significantly between the two groups (p = 0.0085). Conclusion Our findings suggest that metal-ceramic crown copings cemented with self-adhesive resin cement show strong adhesion to composite resin cores associated with glass-fiber posts, thus providing a safe alternative to the use of cast metal posts and cores.

Introduction: the presence of residual microorganisms after chemical-surgical preparation of root canals suggests the use of effective intracanal medication, biologically compatible with periapical tissues. Objective: compare the cytotoxicity of intracanal medications in gingival human fibroblasts. Methods: an experimental study was conducted with four different groups: control (G1), Clindamycin Hydrochloride 2g associated to dexamethasone phosphate 0.32g (Clindex) vehicled in alcoholic solution (G2), Clindex vehicled in polyethylene glycol 400 (G3), and NDP: paramonochlorophenol associated to dexamethasone phosphate 0.32g vehicled in polyethylene glycol 400 and saline solution (G4). The cells were stimulated with the medications for 24, 48 and 72 hours. Cell viability was evaluated with the technique of MTT analysis. Readings were performed in an ELISA spectrophotometer. Results: the groups were analyzed in terms of mitochondrial activity. G2 had the best results in the three times studied, followed by G3 and G4. A statistical analysis was performed (ANOVA and complemented by Tukey's test). Significant differences of 1% were found when comparing G2 and G3 with G4. Conclusion: the Clindamycin dexamethasone combination, irrespective of the vehicle, showed greater cell viability than paramonochlorophenol associated to dexamethasone phosphate.

Introducción: la presencia de microorganismos residuales post-preparación químico-quirúrgico de los conductos radiculares, sugiere el empleo de medicación intracanal eficaz y biológicamente compatible con los tejidos periapicales. Objetivo: comparar la citotoxicidad de medicaciones de uso intracanal en fibroblastos gingivales humanos. Métodos: estudio de tipo experimental. Con cuatro diferentes grupos: control (G1), Clorhidrato de Clindamicina 2g asociado a fosfato de dexametasona 0,32g (Clindex) vehiculado en solución alcohólica (G2), Clindex Vehiculado en polietilenoglicol 400 (G3), y NDP: paramonoclorofenol asociado a fosfato de dexametasona 0,32g vehiculado en polietilenoglicol 400 y solución salina (G4). Las células fueron estimuladas con las medicaciones por 24, 48 y 72 horas y la viabilidad celular fue evaluada usando la técnica de análisis de MTT y la lectura fue realizada en el espectrofotómetro de ELISA. Resultados: fueron analizados por medio de la actividad mitocondrial y mostraron que el G2 obtuvo los mejores resultados en los tres tiempos estudiados, seguido por el G3 y el G4. Se realizó análisis estadístico (ANOVA y complementado con la prueba de Tukey) mostraron diferencias significante a nivel de 1% G2 y G3 cuando se compararon con el G4. Conclusión: la combinación Clindamicina dexametasona independiente del vehículo presentó mayor viabilidad celular que el paramonoclorofenol asociado a fosfato de dexametasona.

The aim of this study was to assess qualitatively, by means of SEM images, the cleaning of the dentin walls of root canals after chemical-surgical preparation using Endo-PTC cream with 0.5% and 1% sodium hypochlorite and different final irrigating solutions. Seventy-two single-rooted human teeth were divided into eight groups and prepared using Endo-PTC cream with sodium hypochlorite (NaOCl) at different concentrations, and irrigated with NaOCl at different concentrations. Final irrigation was performed with either EDTA-T or EDTA-C. The best results were obtained with Group 1, followed by Groups 5, 2, 7, 8, 3, 6 and 4. We can conclude that the use of 0.5% NaOCl during instrumentation and final flush of the root canals was more efficient in cleaning than was 1% sodium hypochlorite. EDTA-T was more efficient in removing smear layer than EDTA-C, and the cervical third presented better cleaning of the root canal walls than did the middle third, which showed cleaner dentin walls than the apical third.

O estudo das imagens do dente em tratamento endodôntico e das suas estruturas anexas favorece a identificação precoce das alterações capazes de comprometer o prognóstico de sucesso. A perfeita informação radiográfica e a correta interpretação comprovadamente orientam a conduta terapêutica, estreitando a relação entre a cura e a patologia. Assim sendo, e devido à importância da fidelidade desse procedimento, os autores apresentam um dispositivo que, acoplado a qualquer posicionador comercializado, possibilita a tomada de imagens semelhantes sob o aspecto das suas dimensões. A importância desse fato surgiu da necessidade do confronto das imagens obtidas entre as sessões do tratamento. Os estudos clínicos indicaram que o posicionador personalizado obtido através de moldagem com material pesado favoreceu sensivelmente as análises comparativas das áreas da superfície radicular externa acometidas de reabsorção cemento-dentinária, como seqüela de trauma dental, bem como as regiões portadoras de rarefação óssea periapical no decorrer da avaliação da neoformação.

The study of images of teeth under endodontic treatment, as well as neighboring structures, favours the early identification of the alterations that may jeopardize a prognosis of success. The perfect radiographic information and the correct interpretation guide the therapeutic approach, enhancing the relationship between pathology and healing. Due to the importance of this procedure, the authors show an instrument that, coupled to any commercial positioner, allows similar image taking under the aspect of its dimensions. The importance of this fact derived from the need of comparing the images obtained during treatment. Clinical studies indicated that the customized positioner, obtained by means of impression with heavy material, increasingly benefited the comparative analysis of areas on the external root surface with cementum-dentin resorption, such as dental trauma sequela and regions with periapical bone rarefaction during the evaluation of the new bone formation.