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Updated: Oct 7, 2026
Guided Endodontics: Three-Dimensional Planning and Template-Aided Preparation of Endodontic Access Cavities
Published on: May 24, 2022
Planning protocol for apical preparation maximizing root canal wall instrumentation and preserving root dentin
Bruno Carvalho de Sousa1, Fabio Luiz Cunha D'Assunção2, Celso Luiz Caldeira3
1Faculty of Dentistry, Sobral campus, Federal University of Ceará, 563 Estanislau Frota street, 62010-560, Sobral, Ceará, Brazil.
Introduction:
This study developed a personalized root canal instrumentation planning protocol designed to minimize uninstrumented canal walls while preserving a remaining dentin thickness (RDT) of at least 0.5 mm and compared it with the best available planning protocol.
Methods:
One hundred maxillary lateral incisors were scanned by micro-CT, and 400 cross-sections were analyzed at 1, 2, 3, and 4 mm from the apical foramen. Canal diameters, aspect ratio, and minimum RDT were measured. Virtual preparation was planned using 5 NiTi systems (ProTaper Ultimate, Reciproc Blue, SRF Sequence MKLife, HyFlex EDM, and WaveOne Gold) individually and a new hybrid protocol allowing instruments from multiple systems and hand K-files when necessary. The primary outcomes were uninstrumented canal surfaces and RDT <0.5 mm. Paired risk ratios (RRs), exact McNemar tests, and Bayes factors (BF10) were calculated.
Results:
The mean canal taper was 0.08 mm/mm, and the mean aspect ratio was 1.40 ± 0.59. Among single-system protocols, ProTaper Ultimate produced the lowest frequency of uninstrumented surfaces (215/400; 53.8%). The new protocol reduced this frequency to 52/400 (13.0%), corresponding to a 76% reduction versus ProTaper Ultimate (RR of 4.13; 95% CI, 3.20-5.34; p <.001). The hybrid protocol was also the only strategy with no sections presenting RDT <0.5 mm (0/400), whereas single-system protocols ranged from 1.8% to 4.5%. The protocol significantly outperformed every tested single-system strategy for both primary outcomes.
Conclusions:
The new personalized hybrid instrumentation planning substantially reduced uninstrumented canal surfaces while preventing critical dentin thinning compared with existing customized single-system protocols.