Comparison of root microcrack formation after root canal preparation using two continuous rotational file systems and two reciprocating systems –An Invitro study

Aim:To compare the incidence of dentinal defects after preparation with reciprocating (Reciproc and WaveOne) and fullsequence rotary ProTaper Universal and Protaper Next instruments. Materials and methods:One hundred human mandibular premolars were randomly assigned to 5 groups (n = 20 teeth per group). The root canals were instrumented by using the reciprocating single-file systems Reciproc and WaveOneand the fullsequence rotary protaper universal andProTaper nextinstruments.One group was left unprepared as control. Roots were sectioned horizontally at 3, 6, and 9 mm from the apex and the sections were then observed under a stereomicroscope. The absence/presence of cracks was recorded, and the data were analysed with a chi-square test. The significance level was set atP= .05. Results:The control group Protaper universal, protaper next, waveone and reciproc caused cracks in 0%, 50%, 35%, 15% and 20% of samples, respectively. A statistically significant difference was found between the reciprocating file groups(WaveOne and reciproc) and the continuous rotation group (ProTaper universal and protaper next) (P< .05). However, no significant difference was found among the 2 reciprocating file groups and 2 continuous rotation group(P >.05). Conclusions:Dentinal micro cracks are produced irrespective of motion kinematics andsuch an incidence is less with instruments working in reciprocating motion compared with those working in continuous rotation.