A Comparison of Zirconia CAD/CAM to Conventionally Fabricated Single Implant Restorations in the Esthetic Zone

Abstract

Objective: This project aimed to determine whether single tooth implant restorations fabricated with CAD/CAM zirconia abutments/porcelain fused to zirconia crowns reveal different biological and esthetic outcomes compared with prefabricated anatomic titanium abutments/porcelain fused to metal crowns in the esthetic zone. Materials and Methods: Thirty patients who needed a single implant restoration in the esthetic zone were included in the study. Twenty-nine patients completed screening, baseline, crown insertion, one-month, six-month and one-year follow-up visits. At the screening visit, the patients were randomly allocated into two groups: the prefabricated anatomic titanium abutments/ porcelain fused to metal crown (Ti) group and the CAD/CAM zirconia abutments/ porcelain fused to zirconia crowns (Zr) group. Plaque and bleeding scores, microbial profiles, probing depth, width of keratinized tissue, vertical bone changes, pink and white esthetic scores, papilla height, and clinical crown height were evaluated through several study time points. Furthermore, patients’ self-esteem, satisfaction, and esthetic evaluations were assessed using visual analog scores (VAS). A simple scale called subjective and objective esthetic classification (SOE) was created to assess the esthetic success of treatment. Statistical analyses were performed using the Mann Whitney U test, Chi-square test and a generalized linear mixed model. Results: All implants were successfully osseointegrated with a 100% survival rate over one year. Biologically, both groups had comparable outcomes except that the mean prevalence of the bacteria in the Zr group was significantly greater than in the Ti group at the final visits for Streptococcus intermedius (p< 0.0001). Also, the Treponema denticola DNA probe signal was lower in the Zr group than the in Ti group at the final visits (p= 0.0007). In addition, the mean of probing depth of the mesial tooth at the mesio-lingual site (p= 0.02) was less in the Zr group. All the esthetic parameters showed no statistically significant differences between both groups. Patients’ self-esteem, satisfaction, and esthetic evaluations did not differ between groups. Conclusion: After one year of clinical performance, the Zr group showed comparable results to the Ti group. This indicated that good clinical, biological and esthetic outcomes could be achieved by either treatment option. Further observations and follow-up are required to evaluate long-term results.