The success of endodontic therapy is based on a number of criteria, particularly the conservation of tooth structure. This principle requires a systematic approach to pulp chamber access. By correlating the occlusal anatomy with the location of the root canal orifice, a dentist may find a number of guidelines for improving access design. In this in vitro study, the authors evaluated 29 human maxillary first molars. Digital radiographs and digital occlusal photographs were taken of each specimen before and after decoronation at the cementoenamel junction (CEJ). The three images were superimposed on one another and evaluated for occlusal and pulpal patterns. The thickness of the pulp chamber walls of the CEJ varied, based on the circumference of individual teeth. In addition, the canal orifices at the pulp chamber floor exhibited a consistent pattern relative to the cusp tips, which may assist in access design.