Study On Dentinal Microcracks During Root Canal Preparation

Compare dentinal microcrack incidence in premolars/molars after canal preparation with ProTaper Gold (PTG), ProTaper Next (PTN), WaveOne (WO), and WaveOne Gold (WOG). 80 premolars (straight canals) and 60 molar roots (curved canals) were prepared using PTG, PTN, WO, WOG, or left untreated (controls). Premolars were sectioned at 3/6/9 mm, molars at 3/6 mm. Microcracks were assessed via staining, stereomicroscopy, and Micro-CT. 1. Premolars: All instruments caused microcracks (highest at 3 mm; P<0.05). Cracks were incomplete (63.6%) or craze lines (36.4%), confined to inner/middle canal walls. 2.Molars: PTN and WO caused significantly more cracks than PTG, WOG, and controls (P<0.05). Molar cracks included complete fractures (21.1%), often extending to outer walls. 3.Key differences: Molar cracks were longer, wider, and more buccal-lingual than premolar cracks. Gold-Wire instruments (PTG, WOG) and reciprocating motion reduced crack risk in molars. 1.Microcrack formation depends on instrument kinematics (reciprocating vs. rotary), material (Gold-Wire vs. M-Wire), and root anatomy. 2.For straight premolars, all systems are safe, but apical regions require caution. 3.Gold-Wire instruments (PTG, WOG) and reciprocating motion reduce crack risk in curved molars. 4.Molar cracks are more severe, highlighting the need for instrument selection based on root complexity.