A Clinical Study Assessing the Influence of Anodized Titanium and Zirconium Dioxide Abutments and Periimplant Soft Tissue Thickness on the Optical Outcome of Implant-Supported Lithium Disilicate Single Crowns

Purpose: To assess the influence of anodized titanium and zirconium dioxide abutments and peri-implant soft tissue thickness on the optical outcome of implant-supported lithium disilicate single crowns. Materials and Methods: Twenty patients with a missing maxillary single incisor, canine, or first premolar received an endosseous implant after a two-stage surgery protocol. After healing and soft tissue conditioning, peri-implant soft tissues were reproduced in the impression, and the thickness was measured. Customized abutments were made of titanium, gold-anodized titanium, pink-anodized titanium, and zirconium dioxide. The definitive prosthesis was a lithium disilicate crown stratified by feldsphatic porcelain. Customized abutments were screwed (35 Ncm), and the crown was temporarily placed on the abutment with a try-in paste. Color measurements were made using a spectrophotometer. CIELab color scale was employed following the formula: ΔE = (ΔL)2 + (Δa)2 + (Δb)2. Data were analyzed using repeated-measures analysis of variance (ANOVA), Bonferroni and Pearson's correlation tests (α = .05). Results: Abutment material type significantly affected the ΔE values at both the periimplant soft tissue (P = .0001) and coronal level (P = .001). The lowest ΔE values were obtained with zirconia abutments at both soft tissue (6.06 ± 3.2) and coronal level (5.76 ± 2.9) compared with those of other abutments (soft tissue: 8.96 ± 3.1 to 11.56 ± 3.4; coronal: 8.66 ± 6.1 to 10.42 ± 6.3). Mean soft tissue thickness (1.63 ± 0.64 mm) affected the ΔE values at the peri-implant soft tissue level for only titanium and pink-anodized titanium abutments (P = .024 and P = .048, respectively). In all conditions, correlation coefficients between ΔE and the abutment materials were higher for titanium (r = -0.544; P = .024) and the least for zirconia (r = -0.313; P = .238) and gold-anodized titanium (r = -0.393; P = .119) abutments. Conclusion: All abutment types demonstrated noticeable color difference at both the soft tissue and coronal levels. Zirconia abutments showed the lowest ΔE values at both measurement zones. Soft tissue thickness did not affect the ΔE values at the periimplant soft tissue level. Keywords: color, implant abutments, lithium disilicate, oral implants, soft tissue, spectrophotometer, titanium, zirconia