Survival and mechanical complications of single- and multiple-unit cement-retained posterior implant-supported restorations with custom CAD/CAM Atlantis titanium abutments: An up to 10-year retrospective analysis

Purpose: To evaluate the survival of and incidence of mechanical complications with single- and multiple-unit cement-retained posterior implant-supported restorations with custom CAD/CAM Atlantis titanium abutments (Dentsply Sirona, Charlotte, NC, USA). Materials and methods: This retrospective clinical study analysed 196 Astra Tech OsseoSpeed TX Internal Hexagon implants (Dentsply Sirona) placed in 85 patients between January 2011 and January 2021. Customised Atlantis titanium abutments and cement-retained metal-ceramic crowns were employed. The clinical outcomes recorded were implant and abutment survival rates, and mechanical complications. The results were analysed according to implant length and diameter, arch, implant position and single- or multiple-unit restoration. Results: Over the observation period (up to 10 years), implant and abutment survival rates were 98.5% and 100.0%, respectively. The mean observation period for the single- and multiple-unit implant-supported restorations was 106.00 ± 20.84 months, with a minimum of 41 months and a maximum of 120 months. For the 67 single-unit and 129 multiple-unit posterior implant-supported restorations, four mechanical complications were recorded: two cases of screw loosening, one case of chipping or fracture of veneering materials, and one case of crown decementation. No screw or abutment fractures were observed. Conclusions: According to the results of this retrospective clinical study, cement-retained posterior implant-supported restorations with custom CAD/CAM Atlantis titanium abutments showed high survival rates over a follow-up period of up to 10 years. No statistically significant differences were recorded when comparing implant position, implant diameter, implant length, single- versus multiple-unit restoration and arch.