Location and dimensions of access cavity in permanent incisors, canines, and premolars

BACKGROUND: Ideal access cavity assures unobstructed straight-line access to the apical third of the root canal and preserves tooth structure. AIM: The aim of the study was to determine the location and dimensions of access cavity with straight-line access in incisors, canines, and premolars and to evaluate the largest diameter of their root canals in the mesiodistal and vestibulooral direction. MATERIALS AND METHODS: Twenty extracted teeth of each group were randomly selected and digitally radiographed from the mesiodistal and vestibulooral direction. Position of the straight-line access midline in relation to anatomical landmarks (incisal edges, fissures, and cusps) was recorded. The largest diameters in mesiodistal and vestibulooral direction were measured. Relative frequencies of access position and mean and standard deviation of both diameters were calculated. RESULTS: For the anterior teeth, the predominant location of straight-line access was from incisal edge, except for maxillary central incisors, where location was equally distributed between incisal edge and oral surface. In mandibular premolars, the straight-line access was positioned vestibular from central fissure. In mesiodistal direction, the largest diameter was found for maxillary central incisors and canines (1.54 mm), while the smallest diameter was found for mandibular incisors (0.64 mm). In vestibulooral direction, the largest diameter was found for maxillary first premolar (5.28 mm), while the smallest diameter was found for maxillary lateral incisor (1.39 mm). CONCLUSIONS: Knowledge of location and size of access cavity facilitates achieving balance between straight-line access to the apical third of the root canal and preservation of tooth structure.