Effect of Cast Modification on Denture Base Adaptation Following Maxillary Complete Denture Processing.

PURPOSE: To investigate the effect of cast modifications on denture base adaptation in coronal and sagittal projections following maxillary complete denture processing.

MATERIALS AND METHODS: A total of 60 edentulous maxillary casts (n = 10) were distributed among six groups. Group 1 was the control group with no modification, groups 2 through 6 included a butterfly postdam preparation, groups 3 and 4 also included a 10-mm wide/4-mm deep box with addition of four round holes in group 4, and groups 5 and 6 also included a 20-mm wide/4-mm deep box with addition of four round holes in group 6. The boxes were prepared at the mid-heel area of the casts. Two layers of baseplate wax (1 mm each) were used to standardize denture base thickness across the groups. A standard technique was used to replicate the denture tooth set-up, and standardized processing was done for all the groups. Following deflasking, casts with the dentures were sectioned in the coronal and sagittal directions. Microscopic pictures were taken at preselected points. Data were organized in tables, and statistical analyses were performed using repeated measure ANOVA, Tukey post hoc tests, and post hoc comparison tests set at 5% level of significance.

RESULTS: Maximum gaps were measured at the mid-palatal area followed by nearby areas and the areas near ridge crests in both coronal and sagittal projections. The analyses revealed significant differences between the groups in coronal projection (1/2, 3/4, 5/6) and sagittal projection (1, 2, 3/4, 5/6) without significant differences within the pairs. The groups were ranked from the highest group 1 to the lowest group 6 relative to the gap means. Post hoc comparisons showed that points 1C and 2A had the highest gap means across the study groups.

CONCLUSIONS: Within the limitations of this study, it can be extrapolated that the denture base adaptation can be effectively increased with the box preparation at the mid-heel aspect of the casts. Significant reduction of gaps was seen when the box size increased from 10 to 20 mm in coronal and sagittal projections; however, the addition of four holes had no significant effect on gap size alterations.