A Clinical Study Assessing 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

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: Delta E = (Delta L)(2) + (Delta a)(2) + (Delta b)(2). Data were analyzed using repeated-measures analysis of variance (ANOVA), Bonferroni and Pearson's correlation tests (alpha = .05). Results: Abutment material type significantly affected the Delta E values at both the peri-implant soft tissue (P = .0001) and coronal level (P = .001). The lowest Delta E 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 Delta E 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 Delta E 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 Delta E values at both measurement zones. Soft tissue thickness did not affect the Delta E values at the peri-implant soft tissue level.