Defense Date

2026

Document Type

Thesis

Degree Name

Master of Science in Dentistry

Department

Dentistry

First Advisor

Awab Abdulmajeed

Second Advisor

Abdulmuhsen Marafi

Third Advisor

Garry Myers

Fourth Advisor

Caroline Carrico

Abstract

Objective:

Accessing canals through full-coverage zirconia crowns is challenging and may increase the risk of misdirection, excessive dentin removal, and prolonged chair time. Guided endodontic access has been proposed to improve efficiency and precision. This study compared the accuracy and time efficiency of guided versus free-hand endodontic access through zirconia restorations. The hypothesis was that guided access would enhance canal localization precision and significantly reduce access time.

Methods:

Thirty-two extracted maxillary premolars were restored with 1-mm–reduced monolithic zirconia crowns (3Y-TZP, Katana HTML, Kuraray, Japan) and mounted in Modupro models. Teeth were assigned to two groups (n = 16 each): guided (CBCT and intraoral scans with fiducial markers used to design and verify 3D-printed guides) or free-hand (no guide or CBCT). Access was performed using round diamond burs until canal orifices were located and straight-line access achieved. Access time was recorded. For fracture load testing, specimens were mounted in acrylic resin and loaded using a universal testing machine with a 4-mm stainless steel indenter at 1.25 mm/min until failure. Fracture load was recorded in Newtons (N). Normality was assessed using the Kolmogorov–Smirnov test. Due to non-normal distribution, medians and interquartile ranges (IQR) were reported. Group comparisons were analyzed using the Wilcoxon rank-sum test with significance set at α = 0.05.

 

Results:

The median time was 58.6 seconds (IQR: 55.8–69.0) for the 3DG group and 245.8 seconds (IQR: 217.2–288.8) for the FH group, with significantly faster access times in the guided group (p < 0.0001). The median fracture load was 1612.9 N (IQR: 1176.8–1801.9) for the 3DG group and 1186.9 N (IQR: 1111.9–1294.5) for the FH group; however, this difference was not statistically significant (p = 0.1486).

Conclusion:

Guided endodontic access significantly reduced procedure time compared with free-hand access and provided a more predictable approach for reaching canal orifices through zirconia crowns. These results support incorporation of guided access in cases with full coverage restorations.

Rights

© The Author

Is Part Of

VCU University Archives

Is Part Of

VCU Theses and Dissertations

Date of Submission

6-10-2026

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