Retrospective study of endodontic treatment performed by undergraduate students using reciprocating instrumentation and single-cone obturation.

OBJECTIVES: The aim of this cross-sectional retrospective study was to evaluate radiographically the technical quality of root canal treatment performed by undergraduate students using reciprocating NiTi instrumentation and single-cone obturation. METHODS: Endodontic treatment on 1102 teeth performed by undergraduate students from the School of Dentistry of the University of Santa Cecilia (Brazil) was evaluated. All root canal preparations were performed using Reciproc files and were irrigated with 1% NaOCl. The root canal was filled with gutta-percha, along with AH Plus sealer, using the single-cone obturation technique. The technical quality of the root canal treatment was evaluated based on immediate postoperative radiographs. Distance between the end of the filling and the radiographic apex, the filling density, and the taper of the root filling was assessed. Inter-examiner agreement statistic (Kappa) and Chi-square statistic test were used for statistical evaluation of the results. Differences were considered statistically significant when p < 0.05. RESULTS: Anterior teeth, maxillary premolars, and molars presented better results than mandibular premolars and molars (p < 0.05). Mandibular premolars presented a high incidence of a short length of obturation (33.34%) and mandibular molars presented a high incidence of overfilling (6.55%). The majority of the treatment analyzed (62.46%) fulfilled all the criteria showing acceptable working length, taper, and density of obturation. Instrument fractures occurred in eighteen root canals (0.81%). CONCLUSIONS: The use of NiTi reciprocating instruments with the single-cone obturation technique provided an acceptable quality of endodontic treatment in the majority of the cases performed by undergraduate students.

Avaliação da eficiência de sistemas rotatórios na desobturação de canais, através da microtomografia de Raios-X / Evaluation of the efficiency of rotary systems on remove filling materials through X-Ray microtomography

O objetivo do presente trabalho foi avaliar, ex vivo, a eficiência dos sistemas rotatórios ProTaper Universal Retreatment Files e Mani Retreatment Files na desobturação de raízes mesiais de molares inferiores, obturadas pela técnica de ondas contínuas de condensação, determinando-se o volume percentual de material obturador remanescente no sistema de canais radiculares, utilizando-se a microtomografia de raios-X. Um total de 18 molares inferiores portadores de dois canais radiculares mesiais que possuíam curvatura entre 25° e 35° e raio de curvatura menor que 10mm, foram preparados até o instrumento 35/.04 Mtwo. Em seguida foram obturados com guta percha e cimento endodôntico AH-Plus pela técnica de ondas contínuas de condensação e mantidos em estufa a 37°C por sete dias. Imagens microtomográficas dos dentes obturados foram realizadas utilizando o microtomógrafo SkyScan 1172 e parâmetros de 100kV e 100A, gerando imagens de tamanho de 11,88m. Em seguida, os dentes foram divididos aleatoriamente em dois grupos experimentais de acordo com o tipo de instrumento de retratamento avaliado, ProTaper Retreatment Universal Files (PR) e Mani Retreatment Files (MR). De início, a desobturação dos canais radiculares foi realizada com a utilização de brocas de largo associadas a uma gota de solvente para que então os instrumentos de cada sistema fossem utilizados até que a desobturação até o nível do comprimento real de trabalho, fosse alcançada. Após novo escaneamento, as imagens foram reconstruídas utilizando-se o software NRecon e analisadas pelo software CTAn, permitindo a obtenção dos dados quantitativos das amostras

Empregou-se o teste t de Student para determinar a ocorrência de diferença estatística entre os grupos experimentais (p < 0.05). Os volumes, inicial e final médios (mm3) de material obturador remanescente foram de 17,72 e 2,12 para o grupo PR e de 16,61 e 3,71 para o grupo MR, respectivamente. O grupo PR apresentou o menor volume percentual médio de material obturador remanescente (12,76 ± 6,93%), quando comparado ao MR (23,54 ± 10,60%), observando-se diferença estatisticamente significante. Nenhum dos dois sistemas testados, foi capaz de remover completamente o material obturador do interior dos canais radiculares. O sistema rotatório ProTaper Universal Retreatment Files mostrou-se mais eficiente que o sistema Mani Retreatment Files na desobturação de canais mesiais de molares inferiores, obturados pela técnica de ondas contínuas de condensação. As características dos sistemas rotatórios de retratamento podem interferir no volume percentual de material obturador remanescente e conseqüentemente na sua eficiência de desobturação.

The objective of this study was to evaluate, ex vivo, the efficiency of rotary ProTaper Universal Retreatment Files and Mani Retreatment Files in removal procedure of the mesial roots of mandibular molars, obturated by the technique of continuous wave of condensation, determining the volume percentage of material remaining filling in root canals, using the X-Ray micro-CT. A total of 18 mandibular molars with two root canals which had mesial curvature between 25° and 35° and the radius of curvature smaller than 10mm, were prepared by the instrument Mtwo size/taper 35/.04. They were then filled with gutta-percha and sealer Ah-Plus by the technique of continuous wave of condensation and maintained at 37°C for seven days. Micro-CT images of the teeth was carried out using the device SkyScan 1172 on 100kV and 100A as parameters, generating images size 11.88 micrometers. Then the teeth were randomly divided into two groups according to the type of instrument retreatment evaluated ProTaper Universal Retreatment Files (PR) and Mani Retreatment Files (MR). Initially, the procedure for remove the root canal obturation was performed with Largo burs associated with a drop of solvent so that the instrument of each system could be used until the complete removal procedure was reached. After re-scanning, the images were reconstructed with the software used NRecon and analyzed by CTAn software, allowing to obtain quantitative data of the samples. We used the Student t test to determine the occurrence of significant differences between experimental groups (p <0.05). The mean initial and final volumes (mm3) of the remaining filling material were 17.72 and 2.12 for the P group and 16.61 to 3.71 for group MR, respectively.

The PR group had the lowest average volume percentage of remaining filling material (12.76 ± 6.93%) when compared to MR (23.54 ± 10.60%), with a statistically significant difference. Neither of the systems tested were able to completely remove the filling material inside the root canals. The rotary system ProTaper Universal Retreatment Files was more efficient than the system Mani Retreatment Files in removal procedure of mesial canals, filled with the technique of continuous wave of condensation. The characteristics of rotary retreatment system may interfere with the volume percentage of remaining filling material and consequently the efficiency of removal procedure.