Influence of preparation features on retention and resistance. Part II: three-quarter crowns

Four three-quarter crown variations were tested for retention and resistance and compared with results of a previous study.¹⁵ Preparations with boxes or four grooves are the most retentive of the three-quarter crown designs used in the study. Lingual placement of proximal grooves enhanced the retention. Three-quarter crowns with V-shaped grooves are the least resistant of the preparation designs with retention/resistance features.