Effect of Orthodontic Brackets on the Accuracy of Apex Locators: A Pilot Study.

The purpose of this study was to evaluate the effect of metal orthodontic brackets on the accuracy of electronic apex locator (EAL). The actual canal lengths (ACL) of 40 mandibular incisor teeth were determined. Then, the teeth were randomly divided into two groups (n = 20). Orthodontic metal brackets were applied in the first group, and no brackets, in the second group. The working length of each tooth was measured with an EAL under 3 test conditions according to the distance between the lip clip and sample tooth. Data were analyzed using one-way repeated measures analysis of variance and Tukey's post hoc tests (p = 0.05). In the bracketed samples, when the lip clip was located at 1 cm and 2 cm from the samples. The mean differences between the EAL measurements and ACLs were statistically higher than those when the samples were located 3 cm from the lip clip (p < 0.05). There were also statistically significant differences between EAL measurements and ACLs in the bracketed samples located 1 and 2 cm from the lip clip (p < 0.05). In the nonbracketed group, the differences between EAL measurements and ACLs were not statistically significant in the samples located 1, 2, and 3 cm from the lip clip (p > 0.05). Use of orthodontic metal brackets can negatively influence the accuracy of the electronic apex locator when the distance between the lip clip and bracket was short. A minimum of 3 cm distance should be kept between the lip clip and tooth in order to make consistent electronic measurements.

Evaluation of Apically Extruded Debris Using Continuous Rotation, Reciprocation, or Adaptive Motion.

The aim of this study was to compare the amount of apically extruded debris during root canal instrumentation using ProTaper Next (PTN), Twisted File (TF) Adaptive, and Reciproc instruments. Forty-five extracted human maxillary canines were selected and randomly assigned into 3 groups. The root canals were prepared using PTN instruments with continuous rotation (n=15), TF Adaptive instruments with adaptive motion (n=15), Reciproc instruments with reciprocating motion (n=15). During the preparations, canals were irrigated using distilled water and material extruded apically was collected in pre-weighed Eppendorf tubes. After a 5-day drying period in an incubator, the tubes were weighed and the dry weight of the extruded debris was calculated. Data distributions were assessed via the Shapiro-Wilk test, and groups were compared via the Kruskal-Wallis test. The greatest amount of debris extruded by TF Adaptive and the least by PTN, but the difference was insignificant between groups (p=0.259). All instrumentation systems were associated with debris extrusion.

Evaluation of the Effect of Rotary Systems on Stresses in a New Testing Model Using a 3-Dimensional Printed Simulated Resin Root with an Oval-shaped Canal: A Finite Element Analysis Study.

INTRODUCTION: This finite element analysis study was aimed at evaluating the effects of rotary systems on stresses in photopolymerized resin root models with oval-shaped canals. METHODS: Among the data collected by computed tomographic imaging, a mandibular second premolar tooth with an oval-shaped canal was selected, recorded as Digital Imaging and Communications in Medicine, and transferred to Materialise's Interactive Medical Image Control System software. Three-dimensional modeling was performed to produce photopolymerized resin root models. Root canals were prepared by OneShape (OS; MicroMega, Besancon, France); ProTaper Universal (PTU; Dentsply Tulsa Dental, Tulsa, OK); WaveOne (WO, Dentsply Maillefer, Ballaigues, Switzerland); Mtwo (MT; VDW, Munich, Germany); Twisted File (TF; Kerr Dental, Orange, CA); ProTaper Next (PTN, Dentsply Tulsa Dental), and hand files (HFs) (control). The models were scanned (micro-computed tomographic imaging; SkyScan 1174; Kontich, Belgium), finite element analysis models were created, and stresses were calculated under 300-N loading (at a 45° angle and vertically). RESULTS: The maximum stress values were found to be higher when the roots were loaded at an angle. The range of the stress values was PTU > MT > WO > HF > PTN > OS > TF. The stresses were forwarded toward the apical area in the PTN, OS, and TF models. When loaded vertically, the highest maximum stress values were recorded in the WO model. High stress concentrations were observed at coronal, thus less stress was forwarded toward the apical, giving an advantage to the root. The range of the others was as follows: PTN ≥ PTU > MT > TF > OS ≥ HF. The TF model showed lower maximum stress values, whereas the HF model showed more homogenous stress distribution. CONCLUSIONS: Considering the stress distributions and stress values within the models, it can be concluded that oval-shaped canals prepared by HFs and WO were less likely to result in root fracture.

Evaluation of apically extruded debris using continuous rotation, reciprocation, or adaptive motion

Abstract The aim of this study was to compare the amount of apically extruded debris during root canal instrumentation using ProTaper Next (PTN), Twisted File (TF) Adaptive, and Reciproc instruments. Forty-five extracted human maxillary canines were selected and randomly assigned into 3 groups. The root canals were prepared using PTN instruments with continuous rotation (n=15), TF Adaptive instruments with adaptive motion (n=15), Reciproc instruments with reciprocating motion (n=15). During the preparations, canals were irrigated using distilled water and material extruded apically was collected in pre-weighed Eppendorf tubes. After a 5-day drying period in an incubator, the tubes were weighed and the dry weight of the extruded debris was calculated. Data distributions were assessed via the Shapiro-Wilk test, and groups were compared via the Kruskal-Wallis test. The greatest amount of debris extruded by TF Adaptive and the least by PTN, but the difference was insignificant between groups (p=0.259). All instrumentation systems were associated with debris extrusion.

Resumo O objetivo deste estudo foi comparar a quantidade de detritos apicalmente extruídos durante a instrumentação do canal radicular usando os instrumentos ProTaper Next (PTN), Twisted File (TF) Adaptative e Reciproc. Quarenta e cinco caninos superiores humanos extraídos foram selecionados e distribuídos aleatoriamente em 3 grupos. Os canais radiculares foram preparados utilizando instrumentos PTN com rotação contínua (n = 15), instrumentos TF Adaptative com movimento adaptativo (n = 15), instrumentos Reciproc com movimento oscilatório (n = 15). Durante os preparos, os canais foram irrigados com água destilada e o material extruído foi coletado apicalmente em tubos Eppendorf pré-pesados. Após um período de secagem de 5 dias numa incubadora, os tubos foram pesados e o peso seco dos resíduos extruídos foi calculado. A distribuição dos dados foi avaliada pelo teste de Shapiro-Wilk e os grupos foram comparados pelo teste de Kruskal-Wallis. A maior quantidade de detritos extruídos foi proporcionada pelo TF Adaptive e a menor pelo PTN, mas a diferença não foi estatisticamente significante entre os grupos (p=0,259). Todos os sistemas de instrumentação promoveram extrusão de detritos apicalmente.