Linguoaxial wall and cervicoincisal dimension of anterior crown preparation: effect on retention

This study sought to evaluate the effect of the linguoaxial wall, a lingual auxiliary groove, and the cervicoincisal dimension of the anterior tooth preparation on retention. A simulated maxillary central incisor was prepared following "ideal" guidelines. The linguoaxial wall of these preparations was modified and the samples were divided into three groups: preparations with a linguoaxial wall (Group 1), preparations with a linguoaxial wall and groove (Group 2), and preparations with no linguoaxial wall (Group 3). Ten metal dies and crowns were fabricated from each preparation group. A universal testing machine subjected cemented crowns to force along the long axis of the dies and load-to-dislodgement was measured. All preparations were shortened by 3.0 mm and crowns for the reduced-height groups were fabricated, cemented, and subjected to similar force. The preparations with the groove produced higher mean retention than the other groups. Among the reduced-height groups, the preparations with the groove also produced higher mean retention than the other groups. There were no differences in mean retention for the short and long preparation heights of each group.