Abstract:
Purpose: To compare the retentive force of the denture on different undercut of modified custom abutments (0.01,0.02,0.03 and 0.04 inch) before and after insertion removal cycle with cylindrical custom abutments were used as a control group by conducting 5 times each. Method: The retentive force was measured before and after 480 insertion-removal cycles by universal testing machine. The data were analyzed using two-way repeated measures ANOVA and Bonferroni (α=0.05) and compared the difference of the retentive force of different undercut of modified custom abutments before and after insertion-removal cycle by one-way ANOVA. Result: The factor between insertion-removal cycle and the amount of undercut gauge affected the retentive force significantly (p<0.05) and statistically significant differences of the retentive force before and after insertion-removal cycle were found in all groups. (p<0.05) Conclusion: No statistically significant differences were found in the retentive force of the cylindrical abutments, 0.01 and 0.02 undercut gauge of modified custom abutments before and after insertion-removal cycle. The retentive force of 0.03 and 0.04 undercut gauge of modified custom abutments were significantly higher than 0.01 and 0.02 undercut gauge of modified custom abutments. The ratio of the difference of the retentive force of different undercut of modified custom abutments before and after insertion-removal cycle is not significantly different.