Objectives: To evaluate the influence of access cavity designs and minimally invasive NiTi rotary files on apical debris extrusion and preparation time.

Materials and Methods: Eighty extracted maxillary first molars with curved mesio-buccal canals were randomly allocated into four groups: conservative or standard access combined with ProTaper Gold (PTG) or TruNatomy (TN) rotary systems. Debris extrusion was quantified, and preparation time was recorded. Data underwent two-way ANOVA and Tukey’s tests.

Results: Both cavity design and file type significantly impacted debris extrusion and preparation time (p<0.05). The conservative cavity combined with TN showed minimal debris extrusion at (245.6 ± 63.6 mg), which was significant compared to other groups (P<0.05); however, the standard cavity with TN had the shortest preparation time at 3.355 min.

Conclusions: Conservative cavities combined with minimally invasive rotary files minimize apical debris extrusion and reduce canal preparation time, supporting conservative endodontic approaches. However, when conservative cavities are combined with larger-taper rotary files, they do not significantly reduce apical debris extrusion.