Abutment-free Tissue-Level Implants for Personalized Monolithic Zirconia Implant Crowns: A Retrospective Cohort Study

Purpose: This study aims to compare the peri-implant bone surrounding a new abutment free tissue-level implant design with classic tissue-level implants restored with titanium-base abutments. Materials and methods: A retrospective cohort study was conducted between 2018 and 2022 in patients requiring dental implants. A total of 53 patients received either a novel abutment-free tissue-level implant (n₁ = 50 sites) or a conventional tissue-level implant (n₂ = 50 sites). Patients were monitored for one year after prosthetic loading, with the primary endpoint being any change in hard tissue around the implant. Bone resorption was evaluated using cone beam computed tomography (CBCT). Statistical analyses included Fisher’s exact test for categorical variables and Student’s t-test for continuous variables. Longitudinal outcomes were assessed using linear mixed models to account for within patient correlations over time. The models incorporated treatment group, time, and their interaction, with statistical significance evaluated using Wald tests. Non-inferiority was assessed with one-sided p-values <0.025, while two-sided p-values <0.05 indicated statistical significance. Results: No significant differences in patient demographics or complications were found between abutment-free and conventional implants. However, abutment-free implants exhibited less buccal bone loss than traditional implants. The abutment-free implant group had significantly lower buccal bone loss (p-values of 0.025 and 0.024 for oral palatal/lingual bone and alveolar ridge width, respectively). Conclusion: The results of this study suggest that abutment-free dental implants offer advantages in reducing buccal bone loss compared to conventional implants, potentially due to their ability to mitigate risks to peri-implant tissues. Further research is warranted to evaluate their long-term efficacy and safety.