Effect of Pattern Elevation on the Fit of Co-Cr Copings Produced for Implant Abutments

Abstract

Objectives: The study's purpose was to evaluate the efficacy of pattern elevation compared to other methods used for fit manipulation of metal copings produced for implant abutments Methods: Seventy-seven pattern resin and eleven wax patterns were produced for Friadent 4.5mm diameter straight abutment and were assigned into eight groups. Four resin groups were elevated from the abutment for 250μ, 500μ, 750μ and 1000μ respectively in order to produce a die spacer effect, then were recapped and remargined with resin, one resin group was elevated for 1000μ then was recapped and remargined with wax, while the other two groups were used without any elevation. The patterns were invested and cast with Co-Cr alloy. One resin group (no pattern elevation) was invested separately and followed a different heating cycle prescribed by the manufacturer to produce extra investment expansion. After casting, the copings were subjected to sequential fitting rounds. The amount of vertical marginal gap was measured after each fitting cycle. And the data were analyzed statistically by ANOVA and Dunnett C Post hoc test. Results: The 1000 μ-elevated wax recapped and remargined group showed significantly better marginal fit at the beginning of the fitting process and less time needed to reach target marginal adaption zones. Compared to the control group (no elevation-pattern resin), only the wax, and 500 μ elevated groups did also show significantly less fitting time. Conclusion: Pattern elevation is effective in reducing the fitting time. However, the recapping and remargining process has a significant influence on effectiveness.