Defense Date


Document Type


Degree Name

Master of Science in Dentistry



First Advisor

Amber Ather

Second Advisor

Garry L. Myers

Third Advisor

Caroline Carrico

Fourth Advisor

Ana Andrada

Fifth Advisor

Aniket Jadhav


Objective: To evaluate the association of portal of exit (POE) of the second mesiobuccal (MB2) canal with the prevalence of apical periodontitis (AP) in previously treated maxillary molars

Methods: Cone beam computed tomography (CBCT) scans of 106 previously treated maxillary molars seen for either recall or retreatment in the past 3 years were included in the study. Scans were reviewed by one endodontic resident and one board-certified endodontist to determine the POE (separate versus common) of the missed MB2 canal and the presence or absence of a periapical hypo-dense area. Association between AP and portal of exit was assessed using Fisher’s exact test. Significance level was set at 0.05

Results: 106 cases with a missed canal were evaluated. Among the 99 cases with apical periodontits, the prevalence of separate POEs was 84% in comparison to 16% for common POE (p-value<0.0001). In teeth with a missed MB2 with separate POE, there was a 94% prevalence of apical periodontitis, in contrast to 89% in teeth with a common POE, with no statistical significance. Teeth with a separate POE were associated with 2.08x the odds of apical periodontitis than those with common canals (95% CI:[0.37-11.65])

Conclusion: A separate portal of exit of MB2 constituted the bulk of cases included in the study. Even though there was a slightly higher prevalence of PARL for separate POEs in comparison to teeth with a common POE, the difference was not statistically significant. Substantial efforts must be directed towards locating and debriding the MB2 canal, irrespective of the portal of exit.


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Available for download on Sunday, April 28, 2024