Bilateral Palatal Root Agenesis of Maxillary Fourth Premolars in 2 Welsh Corgis: A Cone Beam Computed Tomography (CBCT)-Based Case Report

Palatal root agenesis of the maxillary fourth premolar (PM4) is a rarely reported developmental anomaly in dogs. This report describes 2 cases of bilateral palatal root agenesis in Welsh Corgis that had complicated crown-root fractures. Initial intraoral radiography suggested absence of the palatal root; however, cone beam computed tomography (CBCT) with 3-dimensional reconstruction provided definitive visualization confirming complete bilateral absence of the palatal roots and associated root canal systems in both patients. Based on these anatomical findings, conventional root canal treatment was performed only on the mesiobuccal and distal roots, which resulted in favorable clinical outcomes during the follow-up period. Furthermore, a 10-year retrospective review of 6683 dental records across 2 referral hospitals identified only 2 cases among 244 Welsh Corgis, which corresponded to record-based frequencies of 0.03% (95% CI, 0.004–0.108%) in the overall canine population and 0.82% (95% CI, 0.099–2.929%) in Welsh Corgis. These findings suggested that palatal root agenesis of the maxillary PM4, although rare, may occur bilaterally and should be carefully considered during diagnosis and treatment planning of fractured carnassial teeth. This study highlighted the utility of CBCT in distinguishing true root agenesis from other anatomical variations. Although both cases occurred in Welsh Corgis, larger studies are required to determine whether any breed-related tendency exists.