RESUMO
INTRODUCTION: Ultraconservative access cavities (UCACs) have been proposed to reduce crown weakening, but there is no consensus about their design and size and about their advantages and disadvantages, which are also related to how differently they are performed. The purpose of the present study was to evaluate the possible use of a novel Dynamic Navigation System (DNS) in planning and executing UCACs and its precision in vitro, compared with a manual approach (MA) without any guide. METHODS: Twenty radiopaque, artificial teeth replicas were randomly divided into 2 identical groups and scanned using cone-beam computed tomography. In the first group (MA) MB1 canal orifice was reached, starting from the central part of the molar occlusal surface, using a micro endodontic bur. In the second group, DNS allowed to plan and execute a more direct, straight-line truss access. After cavity preparation, teeth were scanned again, and cone-beam computed tomography images were compared. Data were statistically analyzed with analysis of variance test. RESULTS: Significant differences (P < .05) were found in the tested parameters between the 2 groups. The DNS group was significantly more precise, showing smaller mean values in the angulation (4.8°) and in the maximum distance from the ideal position (0.34 mm), when compared with MA group (mean values, 21.2° and 0.88 mm, respectively). CONCLUSIONS: Hence, we may conclude that the use of DNS increased the benefits of UCACs by minimizing the potential risk of iatrogenic weakening of critical portions of the crown and reducing negative influences to shaping procedures.