Effect of continuous rotation and reciprocating motion on dentinal microcrack formation in root canal using single file systems: a sem study

Background: Root canal preparations using (NiTi) rotary instruments induces momentary stress concentrations in the root dentin that lead to formation of microcracks. Objective: The objective was to evaluate the incidence of dentinal microcrack formation after root canal preparation using two Continuous rotation : One Shape , Trunatomy & two Reciprocating motion: Wave one Gold, Reciproc blue single file systems under SEM. Materials and Methods: Sixty freshly extracted single root permanent mandibular premolars were selected, decoronated and divided into four groups(n=15) according to the motion used i.e. continuous rotation: Group 1 A(One Shape), Group 1 B Trunatomy)& reciprocating motion: Group 2 A (Wave one Gold), Group 2 B (Reciproc blue). After instrumentation, specimens were sectioned horizontally at 3 mm, 6 mm and 9 mm from the apex, dried in a critical point dryer and then was mounted on metallic stubs and gold sputtering was done. The examination of the specimens were done under Scanning electron microscope (SEM) at 100X magnification. Result: Minimum amount of microcracks were observed in Group 1 B (Trunatomy) at all the three cross-sectional levels of root. The experimental data was compared using using Pearson chi square test. Dentinal microcrack formation between Group 1A v/s Group 1B andGroup 1 B v/s Group 2 A showed no statistically significant difference at 6mm and 9mm levels, however at 3mm distance from the apex, there was a significant difference among both the groups. There was no significant difference among the other groups. Conclusion: There is no definitive conclusion concerning the clinical implications of these dentinal defects in long term. More studies on this topic and the development of more effective methods and analysis are required.