Fracture resistance and volumetric dentin change after management of broken instrument using static navigation - An in vitro study.

Abstract

Context: Guided endodontics has been revolutionizing endodontics, emphasizing the need to further investigate its capabilities in terms of degrading separated instruments will be of great value.

Aims: The aim of this study was to compare, in vitro, the static endodontic guide and ultrasonic methods for managing separated instruments, focusing on fracture resistance, dentin changes, and procedural time.

Materials and methods: Twenty-two extracted double-rooted maxillary first premolars were decoronated to 15 mm in length and mounted in acrylic resin blocks for standardized cone-beam computed tomography (CBCT) scanning. Size 25/0.06 rotary files were notched at 3 mm and separated in the coronal third of the buccal canals under controlled conditions. Teeth were randomly assigned into two groups (n = 11): Group G utilized static endodontic guides fabricated for instrument degradation, and Group U employed conventional ultrasonic technique for retrieval. Volumetric dentin loss, fracture resistance, and time required for retrieval were evaluated using CBCT scans, universal testing machines, and stopwatch recordings.

Statistical analysis: Normality tested; t-test for parametric, Mann-Whitney for nonparametric.

Results: The ultrasonic group showed significantly higher fracture resistance and less root canal volume increase compared to the static endodontic guide group. However, the ultrasonic group required significantly more time for retrieval. All differences were statistically significant (P < 0.001).

Conclusions: The study compares ultrasonic and static endodontic guides for instrument retrieval, highlighting static endodontic guides' speeds but increased dentin loss, deeming them unsuitable for degrading instruments with burs. Further research is needed.