Materials and Methods: Sixty freshly extracted maxillary incisors teeth collected in saline. Access cavity prepared and canals were made free of bacterial and pulp. The teeth were mounted on the bacteria collecting apparatus. Root canals were contaminated with the Fusobacterium Nucleatum (ATCC25586) and dried at 37°C for 24 h. In Group 1 (Control group): No instrumentation was done and biomechanical preparation done in all other groups with Group 2: Hand K-files, Group 3: Protaper gold, Group 4: K3XF, Group 5: Edge taper platinum, and Group 6: Hyflex CM rotary file systems. Then, the extrude was collected, and it is incubated in Mueller-Hinton agar for 24 h and the number of colony forming units were counted and statistical comparison was done using Kruskal-Wallis test and Mann-Whitney U test.
Results: Hand K-files extruded more bacteria when compared to other four rotary systems, K3XF file system extruded least number of bacteria.
Conclusion: All instrumentation techniques extruded intracanal bacteria apically. However, engine-driven nickel-titanium instruments extruded less bacteria than the manual technique. The K3XF rotary file system comparatively extruded less bacteria than other rotary file systems.
Materials and Methods: A maxillary first premolar typodont tooth was prepared to receive lithium disilicate onlay. Mesio-occluso-distal cavity was prepared with palatal cusp reduction and collar preparation. In the proximal box, gingival seat was placed 1 mm coronal to the cementoenamel junction and mesiodistal width of the seat was kept to 1 mm. Thirty stone models were prepared from thirty rubber base impressions and divided into two groups, based on the technique of fabrication of onlays: (1) Group CL (CAD/CAM lithium disilicate) and (2) Group PL (Pressable lithium disilicate). Fifteen onlays per each group were fabricated by following the manufacturer instructions. Marginal fit of all the samples were analyzed by using stereomicroscope with Image Analysis software. Statistical analysis was done by t-test.
Results: Statistical significant difference was found between both the groups. The lowest marginal discrepancy (41.46 μm) was measured for Group CL (CAD/CAM lithium disilicate) specimens, and the highest (55.95 μm) discrepancy was observed on the Group PL (Pressable lithium disilicate) specimens.
Conclusion: Although there was a statistically significant difference between the two groups, marginal gap of both the groups were in clinically acceptable levels.