Influence of Cervical Preflaring on the Incidence of Root Dentin Defects.

INTRODUCTION: This study evaluated the influence of cervical preflaring on the incidence of root dentin defects after root canal preparation. METHODS: Extracted human maxillary central incisors were selected and allocated to 1 control group and 12 experimental groups (n = 15). Teeth in the control group were left unprepared, whereas the others were prepared using 2 reciprocating single-file systems (Reciproc and WaveOne [WO]), 3 full-sequence rotary systems (ProTaper Universal, ProTaper Next [PTN], and ProFile), and K-files driven by an oscillatory system, with and without cervical preflaring. Roots were then horizontally sectioned at 4, 8, and 12 mm from the apex, stained with 1% methylene blue, and viewed through a stereomicroscope at ×25 magnification. Slices were inspected and the absence/presence of defects (fractures, partial cracks, and craze lines) recorded. Data were analyzed using Kolmogorov-Smirnov and Levene tests followed by the Tukey post hoc test at a significance level of P < .05. RESULTS: No root dentin defects were observed in the control group. WO was associated with a significantly higher number of defects than K-files, ProFile, and PTN (P < .05), but was not significantly different from Reciproc or ProTaper Universal (P > .05). Cervical preflaring significantly reduced the incidence of fractures and other defects in the WO and PTN groups (P < .05). CONCLUSIONS: All instruments caused root dentin defects, regardless of the enlargement or not of the cervical portion. Cervical preflaring was associated with a lower incidence of defects, mainly in root canals prepared with WO and PTN.

The Influence of Cervical Preflaring on the Amount of Apically Extruded Debris after Root Canal Preparation Using Different Instrumentation Systems.

INTRODUCTION: The objective of this study was to evaluate the influence of cervical preflaring on the amount of apically extruded debris after root canal preparation using different instrumentation systems. METHODS: One hundred eighty human maxillary central incisors were selected and randomly divided into 12 groups (n = 15). Root canals were instrumented according to manufacturers' instructions using 2 reciprocating single-file systems (Reciproc [VDW, Munich, Germany] and WaveOne [Dentsply Maillefer, Ballaigues, Switzerland]), 3 full-sequence rotary systems (ProTaper Universal [Dentsply Maillefer], ProTaper Next [Dentsply Tulsa Dental, Tulsa, OK], and ProFile [Dentsply Maillefer]), and K-files (Dentsply Maillefer) driven by an oscillatory system with and without cervical preflaring. Bidistilled water was used as irrigant. Apically extruded debris was collected in preweighed glass vials using the Myers and Montgomery method. After drying, the mean weight of debris was determined using a microbalance. Kolmogorov-Smirnov and Levene tests followed by the Tukey post hoc test were used for statistical analysis. RESULTS: K-files produced significantly more debris than all of the other systems (P < .05). For all systems, cervical preflaring reduced the amount of apically extruded debris when compared with no cervical preflaring (P < .05). CONCLUSIONS: All of the systems extruded debris, irrespective of the preparation technique used (with or without cervical preflaring). Cervical preflaring was associated with the extrusion of smaller quantities of apical debris.

Efecto de la inducción de enfermedad endodóntica sobre el sistema nervioso central (SNC): estudio en ratones / Effect of endodontic disease induction on the central nervous system (CNS): a study in mice

El objetivo de este estudio fue comprender el efecto de la infección periapical asociada a un modelo de estrés sobre los parámetros de evaluación del sistema nervioso central. Para este experimento se seleccionaron 20 ratones machos de la especie Rattus Novergicus en dos grupos, respectivamente, de estrés y apertura (GEA) y apertura (GA). Los procedimientos de inducción de la enfermedad endodóntica se realizaron por medio de una apertura coronaria del 1º molar inferior derecho. Después de la institución del modelo de estrés fue realizada la evaluación motora y psicológica de los animales por medio de pruebas de comportamiento del tipo laberinto elevado en forma de cruz y campo abierto. En relación a la evaluación en el campo abierto no existieron diferencias estadísticas (p>0,05) entre los grupos. Para la evaluación del laberinto en cruz, fueron observadas dos variables. En relación al tiempo de permanencia en el brazo cerrado el GA demostró un mayor tiempo de permanencia comparado al GEA (p<0,05). En relación al brazo abierto, el GEA tuvo un tiempo mayor de permanencia en la región en comparación al GA, inclusive con diferentes estadísticas (p<0,05). Dentro de las limitaciones del estudio, se puede notar que el estrés asociado a la inflamación de los tejidos periapicales llevaron a la modificación del comportamiento del animal.

The aim of this study was to understand the effect of periapical infection associated with a model of stress on the parameters of the central nervous system evaluation. For this experiment we selected 20 male rats divided into two groups: stress and opening group (SOG) and opening group (OG). In the first group, rats were tested for induction of stress associated with endodontic disease through coronary opening of the first lower right molar, the second group, the same procedure was carried out but without the stress partner. After 30 days of the imposition of the stress model was evaluated for motor and mental development of animals through field testing of high-maze behavior in a cross and open. Regarding the open-field assessment there was no statistically significant differences (p> 0.05) for the evaluation of the maze, there are two variables. In terms of time spent in closed arm OG showed a longer hospital stay compared to SOG (p <0.05). Regarding the open design industry, the SOG had a longer hospital stay in the region against the OG, including statistically significant differences (p <0.05). It was seen that the stress associated with inflammation of periapical tissues led to the modification of animal behavior.