Evaluation of Apical Closure Status of Canine, Maxillary Fourth Premolar, and Mandibular First Molar Teeth Using Retrospective Single-Time-Point Radiographic and Computed Tomography Data in Dogs

The age at which tooth apical closure in dogs occurs is important for planning endodontic surgery. Limited previous studies in this area have demonstrated apical closure between 7 and 10 months of age. This study aimed to determine the apical closure status for canine, maxillary fourth premolar, and mandibular first molar teeth based on retrospective computed tomography (CT) and dental radiography data. Seven hundred and eighty-eight teeth from 149 patients were assessed by 2 examiners as either open, inconclusive, or closed. Fifty percent of studied apices were found to be closed by 10 months, and 95% closed by 17 months. Mandibular first molar and maxillary fourth premolar teeth apices were determined to close earlier than canine teeth, with 95% closed by 7 months. Canine teeth apices were found to be closed between 7 and 18 months. In dogs over 25 kg, teeth with closed apices were measured in younger dogs and over a shorter age range (95% were closed between 7 and 13 months) than in dogs under 25 kg (95% were closed between 8 and 17 months). A higher percentage of maxillary canine teeth apices were open at a later date than mandibular canine teeth apices. The results show that while some teeth apices close during the previously reported age range of 7 to 10 months, significant variation exists (7 to 18 months). This should be considered when planning endodontic therapy in young patients.