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Introduction:The aim of the present study was to observe the influence of speed on cracks in root dentin using the ProTaper system and Revo S system at low, medium and high speed. Method: 36 mandibular premolar teeth that had been extracted for different reasons were selected. The teeth were decoronated and were divided into two groups-Group 1-ProTaper system (n-18) and Group 2-RevoS system (n-18). In group 1, 6 roots were shaped at 250rpm, 6 roots were shaped at 300rpm and 6 roots were shaped at 350rpm. Similar procedure was followed for group 2 at 250, 300,350rpm. After root canal procedure, all roots were sectioned horizontally at 3, 6,9mm from apex and were examined under stereomicroscope for presence of cracks. A Z test was used for data analysis. The significant level was set at P<0.05. Results: At 350rpm more percentage of microcracks were observed for both groups when compared to speed at 250 and 300rpm and at 300rpm both systems showed less incidence of cracks. RevoS system showed fewer incidences of cracks at high speed when compared to ProTaper system. Conclusion: In this in vitro study, instrumentation of root canals with RevoS at high speed made teeth less susceptible to cracks when compared to ProTaper system and 300rpm seems to be reasonable speed to use both these rotary files for cleaning and shaping in vivo with fewer incidence of cracks.

Aim:The present study was conducted to evaluate the effect of intraorifice depth on the sealing ability of intraorifice sealing agent using methylene blue as a dye tracer. Material And Method: Twenty extracted premolars were decoronated , cleaned and shaped and obturated with guttapercha points and following which guttapercha was removed from each group at varying depths of 1mm, 2mm and 3mm respectively and these empty canal space were then filled with light cure glass ionomer cement as intraorifice sealing agent and then the microleakage was measured in each group by assessing the amount of dye penetration using a stereomicroscope by using methylene blue as the dye tracer after the specimens were sectioned longitudinally.