Objective:This study investigated whether the canal curvature has an influence on the accuracy of Electronic Apex Locator.Materials and Methods:Sixty mandibular posterior teeth were decoronated. A number (No.) 10 file was inserted into the mesiobuccal canal and radiographs were taken to determine the degree of curvature by Schneider's method. Samples were divided into three groups of mild (<20°), moderate (20-36°) and severe curvature (>36°). After enlarging the orifice, the actual canal length was determined by introducing a file until the tip emerged through the major foramen when observed under 20X magnification. The teeth were embedded in an alginate model and the Root ZX was used to determine the electronic length. The data was analyzed by Kruskal-Wallis test followed by Mann-Whitney test.Results:The difference in measurement of Actual and Electronic working length was statistically significant between group 1 and 2 (P < 0.05) as well as between group 1 and group 3 (P < 0.05) with group 1 showing the lowest difference.Conclusion:Considering ± 0.5 mm as tolerance limit for accuracy, the device was 95% accurate for the mild curvature group and 80% accurate for moderate and severe groups.

Aim:The aim of the study is to quantify the amount of debris extrusion after instrumentation with single-file rotary and reciprocating systems used either with conventional irrigation (CI) or passive ultrasonic irrigation (PUI) systems.Methodology:Sixty extracted human mandibular incisors were randomly assigned to two groups (n = 30); rotary single-file system, One Shape (OS-Group 1) and reciprocating single-file system, WaveOne (WO-Group 2) instruments. The two groups were further subdivided into two subgroups (n = 15); (A) PUI and (B) CI. The apically extruded debris was collected in preweighed glass vials as per the Myers and Montgomery method. After drying, the mean weight of debris was assessed with a microbalance and statistically analyzed using analysis of variance and Student's t-test.Results:The reciprocating file system produced significantly more debris compared to the rotary file system using either of the irrigation systems (P = 0.04). CI produced significantly more (P = 0.02) debris extrusion compared to PUI irrespective of the file system used.Conclusion:Under the conditions of this study, both systems caused apical debris extrusion. Rotary single-file system produced less debris extrusion compared to reciprocating single-file system. Use of PUI may be advocated as an alternative to CI, as it causes lesser apical debris extrusion.

The Silorane-based composites improve the marginal adaptation due to their reduced shrinkage, thereby decreasing the residual stress at the adhesive-tooth interface.

Background and Aim: Durability of the bond between the fiber post and the root dentin are an important issue for providing long-term clinical success. The aim of this study was to assess the influence of riboflavin (RF) application on bond strength of fiber posts to root canal dentin using a self-etch adhesive luting system. Materials and Methods: A total of 40 single-rooted teeth freshly extracted for the orthodontic purpose were decoronated below the cementoenamel junction, and standardized to 14 mm in length. Post space preparation was done up to No. 3 Peeso reamer. Teeth were randomly divided into two Groups: Group 1: Pre-treatment with etchant and RF (n = 20) and Group 2: No pre-treatment with RF (n = 20). Both the Groups were restored with fiber posts bonded with a self-etch adhesive luting cement. Teeth were then stored in distilled water for a period of 3 months at 37°C. 1 mm slices of the coronal and middle third of root were obtained, and push-out bond strength testing was done with a universal testing machine. Failure patterns were assessed under a stereomicroscope at ×20 magnification. Results: The values were tabulated, and statistical analysis was done with the Chi-square test and independent t-test. There was a statistically significant difference in push-out bond strength between the two groups (P < 0.001) and also between the coronal and middle third region. Conclusion: Within the limitations of the study, it can be concluded, that pre-treatment with RF during bonding procedure preserves the bond strength of fiber posts to root dentin.

The stress distribution on endodontically treated teeth varies with different tapers of root canal preparation and thus the fracture resistance. The objective of this study was to evaluate the stress distribution on endodontically treated teeth between three different tapers of root canal preparation during simulated application of loads on the teeth. In this study, mandibular incisors with straight and mature canals were chosen, cleaning and shaping was done using Hyflex Nickel Titanium (NiTi) rotary instruments. The enlargement was done till 4%, 6% and 8% for design 1, 2, and 3 respectively following which cone beam computed tomography (CBCT) scans were taken. Three finite element analysis models were designed by using three taper designs of root canal superimposed on the same external morphology of a single mandibular incisor. These generated models were assigned to a total force of 70N and 100N which was applied parallel to the long axis of the tooth and at 45 degrees to the long axis of the tooth respectively. The von Misses stresses (VM) throughout the tooth structures were calculated and compared. The results showed that the peak VM stress on all models were at the site of incisal load points. The area of peri-cervical dentin experienced highest VM stresses in all the three designs. This study concluded that highest enamel stress at the incisal load points was seen in all three canal preparation and with increasing taper of the canal, the VM stresses increased.