Conservative Dentistry (Endodontics Department), Faculty of Oral and Dental Medicine, Misr International University, Cairo, Egypt. · Associate Researcher Professor, Restorative and Dental Materials Department, Oral and Dental Research Institute, National Research Centre, Giza, Dokki, 12622, Egypt. · Professor of Endodontics, Ain Shams University, Cairo, Egypt.
Background: Removing fiber posts during endodontic retreatment remains challenging due to their strong adhesive
bonding to radicular dentin, which increases the risk of excessive dentin loss and structural compromise. Guided
endodontic navigation has recently gained attention as a technique capable of enhancing precision and minimizing
iatrogenic damage.
Aim:To compare and asses the fracture resistance of teeth following fiber-post removal using two techniques
conventional freehand removal and static guided endodontic navigation using two instrument systems: ultrasonic tips
and Endo Tracer burs.
Materials and Methods: 36 human extracted mandibular premolars with standardized morphology were prepared
using a rotary nickel– titanium system and root canal filled using the single obturation cone technique and AH Plus
root canal sealer. Fiber posts (0.8 mm, 2% taper) were cemented using dual-cure resin cement. Teeth got mounted in
custom U-shaped epoxy resin molds simulating the dental arch. Group I underwent conventional freehand post
removal, while Group I used static guided navigation designed through the merging of CBCT and optical surface
scans. Groups were further subdivided into two subgroups in accordance with the instrument type (ultrasonic tip
ET18D or Endo Tracer bur). Fracture resistance was then measured with the use of an Instron Universal Testing
device. Finally, data was by using two-way ANOVA and independent t-test. Results: Guided navigation significantly
increased fracture resistance compared to the conventional technique (p < 0.001). Ultrasonic instrumentation
demonstrated higher fracture-resistance values than burs in both groups, with statistically significant differences within the guided technique (p = 0.005). No significant interaction was found between the technique and instrument type (p = 0.366).
Conclusion: Static guided endodontic navigation preserved radicular dentin and resulted in significantly higher
fracture resistance than conventional freehand post removal. Ultrasonic instruments exhibited superior performance
compared with burs. Guided navigation represents a safer and more conservative approach for fiber-post removal.
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