Comparative analysis of auxiliary retentive factors affecting retention of complete cast metal crown
AIMS: To compare and evaluate the effect on retention by the provision of auxiliary retentive features i.e. two opposing grooves or two opposing boxes in the preparation of complete crowns of varying heights. METHODS AND MATERIAL: Steel dies prepared without auxiliary retentive factors and with retentive grooves and boxes were cemented with cast crowns and systematically grouped into three classes and the retentive forces were measured using instron testing machine. STATISTICAL ANALYSIS USED: ANOVA and Student's "t" test were used to get the significant results. RESULTS: The mean forces required to dislodge cemented crowns from the respective dies were maximum for the dies with preparation height of 8 mm with proximal box incorporated (Subgroup IIIC2) i.e. 34.90 kg and minimum for the dies with preparation height of 4 mm with no auxiliary feature (Subgroup IA) i.e. 12.19 kg. CONCLUSIONS: The increase in retention by providing additional retentive features like grooves and boxes has been found to be statistically significant. These are recommended to be created while preparing teeth on short clinical crowns.