3D EVALUATION OF MICROGAPS AT THE IMPLANT-ABUTMENT CONNECTION BEFORE AND AFTER THERMODYNAMIC CYCLING

Purpose: To analyze the microgap changes between hybrid -abutment crowns made of two materials and three internal taper connection implants with different connection designs before and after thermodynamic loading. Materials and Methods: A total of 30 implants -10 each of Straumann Bone Level Implant -RC (STR); GC AADVA Implant (AAD); and Astra-Tech OsseoSpeed EV (AST) -were included in this laboratory study. Each implant had an internal taper connection, but their designs were slightly different. Five hybrid -abutment crowns were fabricated using a lithium disilicate ceramic (LD), and five were fabricated using polymethylmethacrylate (PMMA) with CAD/CAM technologies for each implant system, providing six sample groups STR-LD, AAD-LD, AST-LD, STR-PMMA, AAD-PMMA, and ASTPMMA. The microgap volume was measured using micro -CT images obtained before and after thermodynamic loading equivalent to 4 months of clinical use. Student ttest, one-way ANOVA, and Tukey test were used for comparisons. Results: The greatest microgap volume increase was recorded (3.405% +/- 1.567%) in the AST-LD group, and the lowest increase (0.45% +/- 0.373%) was in the STR-PMMA group. A statistically significant difference in microgap increase was not detected among PMMA and LD groups: for STR-LD/STR-PMMA (t test: P = .273); for AAD-LD/AAD-PMMA (t test: P = .374); and for AST-LD/AST-PMMA (t test: P = .268). However, the difference in the microgap increase between the different implant systems was statistically significant. Conclusions: The microgap between hybrid -abutment crowns and implants increased after short-term thermodynamic cycling. Hybrid -abutment crowns with different elastic modulus showed similar microgap increase. The geometric shape of the connection influenced the microgap increase. Intl Prosthodont 2024;37:e99 -e111. doi: 10.11607/ijp.8308