Avaliação do desvio apical em canais instrumentados pelos sistemas K3 e ProTaper

OBJECTIVES: this study evaluated the apical deviation of curved root canals instrumented with K3 and ProTaper systems. MATERIAL AND METHODS: twenty root canals of human maxillary and mandibular first molars were employed, which were divided into 2 groups: group A (10 teeth) was instrumented with the K3 system, and group B (10 teeth) with the ProTaper system. Evaluation of deviation was performed by double radiographic exposure. Radiographs were achieved before and after instrumentation, with 0.3-second, thus allowing superimposition of images. Three-dimensional computerized tomograph was performed in 3 specimens in each group, as an additional means to evaluate the apical deviation. RESULTS: were evaluated by the parametric test Student-Newman-Keuls at 5%, which did not reveal significance between groups concerning the apical deviation. The results of computerized tomograph images demonstrated that the larger deviation of the root canal occurred at the distolingual area for both systems. CONCLUSIONS: both techniques produced a mild apical deviation. Computerized microtomography was shown to be accurate for experimental endodontics studies.OBJETIVOS: avaliar o desvio apical de canais radiculares curvos instrumentados pelos sistemas K3 e ProTaper. MATERIAIS E MÉTODOS: foram utilizados 20 canais radiculares de primeiros molares superiores e inferiores humanos, os quais foram divididos em 2 grupos, o grupo A (10 dentes) foi instrumentado pelo sistema K3 e o grupo B (10 dentes) com o sistema ProTaper, a forma de avaliação do desvio foi a dupla exposição radiográfica. As tomadas radiográficas foram feitas antes e após a instrumentação, com um tempo de 0,3 segundos em cada exposição, ocorrendo assim, sobreposição das imagens. Em 3 espécimes, de cada grupo, foi realizada a tomografia computadorizada tridimensional, como forma adicional de avaliar o desvio apical . Os resultados obtidos foram avaliados pelo teste paramétrico Student-Newman-Keuls 5% o qual denotou não haver significância em relação ao desvio apical entre os grupos estudados. Os resultados das imagens de tomografia computadorizada mostraram que o maior desvio do canal radicular ocorreu na área disto-lingual, para ambos os sistemas estudados. CONCLUSÃO: ambas as técnicas promoveram desvio apical. A tomografia computadorizada revelou ser um método de análise promissor em estudos in vitro na área de endodontia

Fracture of abutment screw supporting a cemented implant-retained prosthesis with external hexagon connection: a case report with sem evaluation

One of the causes of implant failures in cemented implant-retained prostheses is the fracture of abutment screw or UCLA abutment. This article reports a case of simultaneous fracture of two UCLA abutments screws occurring in an implant-supported prosthesis placed in the mandibular molar region. The fractured structures were examined under scanning electron microscopy to investigate the probable causes of the failure, which were not related to failures on materials or fabrication of the screws, but rather were due to shear forces. The misfit in cemented prostheses may be the most likely cause of shear force generation

Wear of K3 and ProTaper files after simulated clinical use in curved canals

Objective: To assess wear, after simulated clinical use of K3 (SybronEndo, Orange, CA, EUA) and ProTaper files (Dentsply-Maillefer, Tulsa, Oklahoma, EUA) in 46 mesiovestibular roots of human maxillary first molars, recently extracted and with mean angulation of 40°.Methods: The teeth were divided as follows: a) K3 (SybronEndo, Orange, CA, EUA) (with radial bands) and b) ProTaper (Dentsply-Maillefer, Tulsa, Oklahoma, EUA) (without radial bands). The files were assessed by scanning electronic microscopy before first use to visualize fabrication defects, and after 7 and 13 cycles of debridement in the canals. Debridement with files K3 (SybronEndo, Orange, CA, EUA) and ProTaper (Dentsply-Maillefer, Tulsa, Oklahoma, EUA) was performed in accordance with the manufacturers’ recommendations. The criteria for wear assessment were: defects (stretching, shortening/spiral inversion, presence of craters), oblique cracks and fracture. After assessment by SEM and before they were used, metal barbs on the crest of the spirals and oblique scratches due to the machining process were found in all the files.Results: In the K3 system (SybronEndo, Orange, CA, USA), after being used seven times, all the instruments showed cutting angle defects,and 25/08 and 25/10 had oblique cracks in the body of the active part leading to ductile fracture after being used for the eighth time. In the ProTaper system (Dentsply-Maillefer, Tulsa, Oklahoma, USA), after being used seven times, in addition to cutting angle defects, the files also presented cracks, and ruptile fracture occurred in F3 during use for the thirteenth time. At the end of preparation, craters were seen along the active part of the files.Conclusion: In the final analysis, it was seen that the system are equivalent with regard to the defects found, irrespective of the active part design,being proportional to the number of cycles of use, and these defects could act as points of greater fragility, favoring fracture

Evaluation of apical deviation in root canals instrumented with K3 and ProTaper systems Avaliação do desvio apical em canais instrumentados pelos sistemas K3 e ProTaper

OBJECTIVES: this study evaluated the apical deviation of curved root canals instrumented with K3 and ProTaper systems. MATERIAL AND METHODS: twenty root canals of human maxillary and mandibular first molars were employed, which were divided into 2 groups: group A (10 teeth) was instrumented with the K3 system, and group B (10 teeth) with the ProTaper system. Evaluation of deviation was performed by double radiographic exposure. Radiographs were achieved before and after instrumentation, with 0.3-second, thus allowing superimposition of images. Three-dimensional computerized tomograph was performed in 3 specimens in each group, as an additional means to evaluate the apical deviation. RESULTS: were evaluated by the parametric test Student-Newman-Keuls at 5%, which did not reveal significance between groups concerning the apical deviation. The results of computerized tomograph images demonstrated that the larger deviation of the root canal occurred at the distolingual area for both systems. CONCLUSIONS: both techniques produced a mild apical deviation. Computerized microtomography was shown to be accurate for experimental endodontics studies.<br>OBJETIVOS: avaliar o desvio apical de canais radiculares curvos instrumentados pelos sistemas K3 e ProTaper. MATERIAIS E MÉTODOS: foram utilizados 20 canais radiculares de primeiros molares superiores e inferiores humanos, os quais foram divididos em 2 grupos, o grupo A (10 dentes) foi instrumentado pelo sistema K3 e o grupo B (10 dentes) com o sistema ProTaper, a forma de avaliação do desvio foi a dupla exposição radiográfica. As tomadas radiográficas foram feitas antes e após a instrumentação, com um tempo de 0,3 segundos em cada exposição, ocorrendo assim, sobreposição das imagens. Em 3 espécimes, de cada grupo, foi realizada a tomografia computadorizada tridimensional, como forma adicional de avaliar o desvio apical . Os resultados obtidos foram avaliados pelo teste paramétrico Student-Newman-Keuls 5% o qual denotou não haver significância em relação ao desvio apical entre os grupos estudados. Os resultados das imagens de tomografia computadorizada mostraram que o maior desvio do canal radicular ocorreu na área disto-lingual, para ambos os sistemas estudados. CONCLUSÃO: ambas as técnicas promoveram desvio apical. A tomografia computadorizada revelou ser um método de análise promissor em estudos in vitro na área de endodontia