Comparative Assessment of Observed Dentinal Defects Following Root Canal Preparation With TruNatomy, ProTaper Next, and Dia-X Nickel-Titanium Rotary Systems: An In Vitro Study.

Endodontic treatment relies on effective root canal preparation using nickel-titanium (NiTi) rotary instruments; however, dentinal defects may be observed following mechanical canal preparation. A total of 40 extracted human mandibular premolars with single roots and single straight canals were randomly allocated into four groups (n = 10), control (unprepared), TruNatomy (TRN), ProTaper Next (PTN), and Dia-X. Root canal was prepared using an ENDO-MATE DT endodontic motor (NSK, Japan), and horizontally sectioned from the apex using a low-speed diamond disc, corresponding to apical, middle, and coronal root thirds, respectively. Dentinal microcracks were evaluated under a stereomicroscope at ×20 magnification. Dentinal defects were observed in all instrumented groups, while the unprepared control group showed the lowest incidence, with defects detected at the apical and coronal thirds (10% each). No statistically significant differences were found among the three rotary systems at the apical (p = 0.211), middle (p = 0.069), or coronal (p = 0.600) levels. However, overall comparison showed a statistically significant difference among groups (p = 0.043), with significant differences between the control group and TRN (p = 0.045), PTN (p = 0.045), and Dia-X (p = 0.010). Dentinal defects were detected at different root levels following preparation with all three rotary systems, with higher overall defect incidence than in the unprepared control group; however, the present methodology does not allow definitive attribution of these defects to instrumentation.