The intercuspal and interorifice distances of maxillary molars: A cone-beam computed tomography study

Proper and conservative endodontic access cavity preparation is a crucial step in performing a successful root canal treatment that ensures a long-term prognosis. This study aimed to evaluate the intercuspal and interorifice length of maxillary first and second molars using cone beam computed tomography (CBCT).

The CBCT scans of 400 mature and intact maxillary first and second molars (16, 17, 26, and 27) were evaluated. The measured variables included the distances between the buccal cusps (intercuspal distance) and buccal orifices (interorifice distance), the interorifice/intercuspal ratio, and the angle at the intersection of interorifice and intercuspal lines. The variables were compared between different teeth and between male and female patients.

The interorifice and intercuspal distances were significantly greater in males compared to females (P<0.05), except for the intercuspal distance in the left maxillary second molar (P=0.056). There was a statistically significant difference concerning the angle formed between the interorifice and intercuspal lines among tooth numbers 26 and 27 (P=0.044). The interorifice/intercuspal ratio was significantly different between the maxillary first and second molars on the right (P=0.006) and left sides (P<0.001).

The angle formed between the intercuspal and interorifice distances and the interorifice/ intercuspal ratio was greater in the maxillary first molars compared to the second molars. Moreover, males generally had larger internal and external anatomical features than females. Hence, when preparing a conservative access cavity in maxillary molars, clinicians are advised to consider both the external tooth anatomy and the patient's gender as important factors