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AIMS: The aim of this study is to compare three different methods of measuring root canal curvature and its correlation with canal access angle (CAA) in curved mesiobuccal canals of permanent mandibular first molars. MATERIALS AND METHODS: Sixty human mandibular first molars were used in this study. Standardized access cavities were prepared. After endodontic access, a size 10 K-file was placed in the mesiobuccal canal extending to the apical foramen, and radiographs were taken. Radiographs of each root canal were taken in buccolingual direction with the long axis of the root perpendicular to the central X-ray beam. After that, the radiographs were scanned with a computer Scanner. The angles were measured using the Schneider method, Weine's method, Lutein's method, and correlated with the CAA method. The angular and linear values used in this study were plotted, and the pertinent measurements were made using the program AutoCAD R12. STATISTICAL ANALYSIS: The resultant values were evaluated statistically using ANOVA test and Pearson correlation and multiple regression analyses (P = 0.001). RESULTS: Lutein's method is as effective as the Schneider's method, Wein's method and CAA. method in evaluating root canal curvature. CONCLUSIONS: Scheider/Wein/Luiten method, together with CAA method, may be considered as a reliable guideline for preoperative assessment of canal curvature.

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The curved and dilacerated roots in the posterior teeth often present the major challenge to the clinicians during the endodontic treatments. The efficient biomechanical preparation is also affected by improper instrumentation in the curved or the constricted canals. The use of conventional instruments and techniques in the dilacerated roots may develop ledges, fractured instruments, and canal blockages which further complicate the endodontic treatments. The introduction of ProTaper Universal rotary instruments has made a significant impact in the biomechanical preparation of root canals systems. However, the fracture rate of these files and inconvenience to treat the posterior teeth in reduced mouth opening conditions limits their successful usage in endodontic treatments. The ProTaper Next rotary instruments have noted advantages such as increased flexibility, higher strength, and wear resistance over the conventional rotary endodontic systems. The current case series discusses the endodontic treatment of three severely curved root canal systems successfully treated with ProTaper Next rotary endodontic system.

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BACKGROUND: The process of cleaning and shaping the canal is not an easy goal to obtain, as canal curvature played a significant role during the instrumentation of the curved canals. AIM: The present in vivo study was conducted to evaluate procedural errors during the preparation of curved root canals using hand Nitiflex and rotary K3XF instruments. MATERIALS AND METHODS: Procedural errors such as ledge formation, instrument separation, and perforation (apical, furcal, strip) were determined in sixty patients, divided into two groups. In Group I, thirty teeth in thirty patients were prepared using hand Nitiflex system, and in Group II, thirty teeth in thirty patients were prepared using K3XF rotary system. The evaluation was done clinically as well as radiographically. The results recorded from both groups were compiled and put to statistical analysis. STATISTICAL ANALYSIS: Chi-square test was used to compare the procedural errors (instrument separation, ledge formation, and perforation). RESULTS: In the present study, both hand Nitiflex and rotary K3XF showed ledge formation and instrument separation. Although ledge formation and instrument separation by rotary K3XF file system was less as compared to hand Nitiflex. No perforation was seen in both the instrument groups. CONCLUSION: Canal curvature played a significant role during the instrumentation of the curved canals. Procedural errors such as ledge formation and instrument separation by rotary K3XF file system were less as compared to hand Nitiflex.

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The unique morphology of dilacerated and S-shaped root canals often pose utmost challenges in their endodontic management. Common causes of failures in such cases are primarily related to procedural errors such as ledges, fractured instruments, canal blockages, zip and elbow creations. Knowledge of dental anatomy and its variations is essential for the success of endodontic treatment. A clinician is required to have an insight of the morphology of tooth related to its shape, form and structure before commencing treatment. Routine periapical radiographs aids in assessing these morphological variations in the root canal system. This article gives a review of the literature and reports an interesting case of dilacerated and S-shaped root canals of adjacent teeth in the same patient.

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The aim of this study was to radiographically investigate the curve existing in slightly curved mesiobuccal canal of mandibular first molar by applying Piecewise straight line approximation. Extracted human mandibular molars were radiographed and one hundred radiographs were selected whose mesiobuccal canal showed slight curvature (10-20°) according to Schneider's method. The curves were traced and analyzed using Piecewise straight line method. Each curve was considered as a unit consisting of six different pieces of straight lines joining at seven specific points and the angle of curvature at these points was determined using the slope formula. All curves analyzed in this study had varying degrees of curvatures at different points on the curve. Maximum curvature (0.40°) was recorded at the middle third of the root canal. Within the limitation of the study, significant curvature occurs through out the curve existing in the mesiobuccal canal of mandibular first molar and the middle third of the curve showing greater degree of curvature. There is a possibility of greater curvature occurring in the coronal third of the curve. Though three dimensional studies would be more appropriate, Piecewise straight line approximation may be a better method than existing methods to simulate canal geometry.

El objetivo de este estudio fue investigar radiográficamente la curva existente en el canal radicular mesiobucal ligeramente curvado del primer molar inferior mediante la aplicación de aproximaciones a segmentos de línea recta. Se utilizaron molares inferiores humanos extraídos que fueron radiografiados. Fueron seleccionadas, según el método de Schneider, 100 radiografías cuyo canal mesiobucal mostró una ligera curvatura (10-20°). Las curvas fueron delineadas y analizadas mediante el método de aproximación a segmentos de línea recta. Cada curva se consideró como una unidad que consta de seis diferentes segmentos de línea recta que unen a siete puntos específicos y el ángulo de curvatura en estos puntos se determinó utilizando la fórmula de la pendiente. Todas las curvas analizadas en este estudio tenían diversos grados de curvaturas en diferentes puntos de la curva. La curvatura máxima (0,40°) se registró en el tercio medio del canal radicular. Dentro de la limitación del estudio, una curvatura significativa se produce a través de la curva existente en el canal mesiobucal del primer molar inferior y el tercio medio de la curva que muestra un mayor grado de curvatura. Existe la posibilidad que ocurra una mayor curvatura en el tercio coronal de la curva. Aunque un estudio tridimensional sería más apropiado, la aproximación a segmentos de línea recta puede ser un mejor método que los existentes para simular la geometría del canal.

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Objective:To study the mathematical relation between the measurements of root canal curvature obtained by Schneider's method(?_S) and Weine's method(?_W).Methods:The axis of a curved root canal was simplified by an arc (whose radius was r and central angle ?) and 2 tangent line segments (whose lengths were l_1 and l_2),the relation of ?_S and ?_W was studied with the help of mathematical analysis according to the different ways of determining the measured angles on the simplified axis.The graphs of the function were analysed.Results:The following formulas were proved:(1)tan?_S=(1-cos?_W+ ksin?_W)/(sin?_W+kcos?_W),k=l_2/r;(2)?_W/2≦?_S≦?_W.If ?_W was in the interval [0,?],a proximate linear correlation existed between ?_S and ?_W.Conclusion:There is a complex function between the 2 angles(?_S and ?_W) measured by Schneider's method and Weine's method,the ratio of the length of the apical straight part to the radius of the canal curvature is an important factor determining the different values of ?_S and ?_W.