Aim: The aim of the study was to evaluate the canal configuration in the mandibular premolars in Delhi/NCR population of North India using cone-beam computed tomography (CBCT). Materials and methods: About 120 CBCT scans were assessed for the root canal configuration in the mandibular premolar according to Vertucci classification. The existence of bilateral symmetry of configuration in the right- and left-side premolars and any gender difference was also studied. Chi-square test was used for statistical analysis. Results: Type I configuration was the most common in both mandibular premolars. In mandibular first premolar, there was 32.3% chance of canal variation from type I, and in the second premolar, approximately, 18.2% chances of variation exists. No gender difference was observed and bilateral symmetrical existence of canal configuration was seen. Conclusion: The most prevalent configuration in mandibular premolars is type I. In the mandibular second premolar, chances of variant configuration are less as compared with the first premolar.

Aim and objectives: To evaluate and compare the depth of penetration of 5.25% sodium hypochlorite solution using different irrigation needles and activation systems using radiographic analysis. Materials and methods: Sixty permanent single-rooted mandibular premolars were selected. The four groups (n = 15) based on the type of irrigation needle used were randomly selected from among the 60 samples, and each group was then subdivided into three subgroups (n = 5) according to the activation method. The crowns were decoronated and root canal preparations were done using hand file systems. Radio labeled 5.25% sodium hypochlorite was used as root canal irrigant. The penetration depth of the irrigant was observed with the aid of a radiograph comparing conventional irrigation needles with side vents, double side vents, and TruNatomy needles and with various activation strategies. The data were statistically analyzed using two-way ANOVA. Results: Except side vent and double side vent needles, all needles appear to significantly differ according to pairwise testing for activations. In comparison to other needles, TruNatomy needles demonstrated greater depth of penetration, whereas conventional needles showed the least depth of penetration of the irrigant. All three systems differ significantly in terms of the activation system. When compared to manual dynamic activation (MDA) and ultrasonic systems, the Endo activator produced the best results.

Objective: Type IX GIC is a preferred permanent restorative material in primary teeth for its tooth-colored restorative material, chemical bonding to tooth structure, better physical properties and fluoride release. This comparative study was done to evaluate physical properties of Cention-N with type IX GIC as manufacturer's claims better properties over GIC. Materials and methods: About 100 samples of 10 mm diameter and 3 mm thickness were made from Type IX GIC and CN using Teflon molds and stored in artificial saliva at pH (5.5) and stored individually in sterile plastic container at a constant temperature during the entire experiment. They were divided into two equal groups (group A and B). Samples from group A were used to determine the change in mass and pH and group B were used to determine fluoride release at different time intervals of 1 week and 1 month and was evaluated using electronic weighing machine, digital pH meter, and spectrophotometer. Results: Statistically significant pH and fluoride release were observed in CN both at the end of 1 week and 1 month, and a significant change in mass was observed in Type IX GIC at the end of 1 month. Conclusion: Cention-N can be a better alternative as it demonstrated an increase in pH and fluoride release than Type IX GIC.

Aim: To evaluate and compare the microhardness of suprananospherical composite and nanohybrid composite after bleaching with 15%; 35% hydrogen peroxide (HP); and 15% carbamide peroxide (CP). Materials and methods: A total of 64 disk-shaped composite specimens were prepared. Groups I and II constitute 32 composite disks made from suprananospherical composite and nanohybrid composite, respectively. Based on the bleaching agent used, each group was subdivided into four subgroups. Subgroups IA and IIA were subjected to bleaching with 15% HP for 15 mins for 10 days. Subgroups IB and IIB were subjected to bleaching with 35% HP for 45 minutes (three sequential 15-minute applications) once a week for three consecutive weeks. Subgroups IC and IIC were subjected to bleaching with 15% CP for 4 hours per day for 14 days. Subgroups ID and IID were kept as control groups where specimens were kept in distilled water for 14 days. After the bleaching procedure, composite disk specimens were subjected to the Vickers microhardness test. Results: Suprananospherical composite showed more reduction in microhardness values than nanohybrid composite. Suprananospherical composite bleached with 35% HP with a ΔH value of 1.248 ± 1.319 showed the highest decrease in microhardness. There was no statistically significant difference between the microhardness of suprananospherical composite and nanohybrid composite after bleaching. About 15% CP caused the least reduction in microhardness in nanocomposites compared to 15 and 35% HP. Conclusion: Suprananospherical and nanohybrid composites exhibited a reduction in microhardness after bleaching with no significant difference between the two composites. About 15% CP caused the least reduction in microhardness values of nanocomposites compared to 15 and 35% HP. Clinical significance: Direct composite resin materials due to their organic matrix are more prone to chemical alteration by bleaching. Reduced surface hardness may affect the durability of restoration.