Bone-Level Versus Tissue-Level Titanium Dental Implants: A Comparative Cross-Sectional Study.

Objectives
To compare the long-term survival rate and prevalence of peri-implant diseases between bone-level (BL) and tissue-level (TL) titanium implants. The secondary objective was to assess the effect of implant diameter and other risk indicators of peri-implant diseases on the outcomes of implant therapy.Materials And Methods
Adult patients with at least one non-molar implant-supported prosthesis (ISP) were included in the study. Relevant clinical and radiographic outcomes, along with patient-related, anatomical, surgical and prosthetic-related factors, were analysed.Results
A total of 266 patients and 336 ISPs were included after a mean follow-up of 11.2 ± 1.5 years. Implant survival rates at the implant level were 99.4% and 98.2% for BL and TL implants, respectively. The prevalence of peri-implant health, mucositis and peri-implantitis was comparable between BL (21.1%, 67.5% and 11.4%, respectively) and TL implants (20.5%, 70.5% and 9.0%). Implants with a diameter of 3.3 mm showed lower peri-implantitis rates (7.2%) compared to those with 4.1 mm (13.3%; p = 0.02). Notably, 3.3 mm TL implants exhibited a significantly lower peri-implantitis rate (4.8%) than BL implants (9.6%; p < 0.001). Multilevel regression at the implant level showed that parafunctional habits (OR = 0.33, 95% CI: 0.12-0.91) and greater mucosal thickness (OR = 0.44, 95% CI: 0.32-0.60) were cross-sectionally associated with decreased odds of mucositis, whereas higher plaque scores were cross-sectionally associated with increased odds (OR = 1.29, 95% CI: 1.03-1.61). Age was cross-sectionally associated with peri-implantitis (OR = 0.96, 95% CI: 0.93-0.99), higher plaque score (OR = 1.45, 95% CI: 1.11-1.90), larger implant diameter (OR = 2.98, 95% CI: 1.19-7.45) and smoking (OR = 4.54, 95% CI: 1.42-14.5), while greater mucosal thickness (OR = 0.17, 95% CI: 0.08-0.37) was cross-sectionally associated with a reduced risk of developing this condition.Conclusions
BL and TL implants at non-molar sites exhibited comparable survival and peri-implant disease rates. However, TL implants with 3.3 mm diameter showed lower peri-implantitis rates. A higher plaque score increased the risk of both mucositis and peri-implantitis, whereas smoking was a strong risk indicator for peri-implantitis. Greater mucosal thickness was protective against both conditions.