Influence of Abutment Characteristics on Marginal Bone Level Changes in Immediate Loading Implant-Supported Full-Arch Fixed Dental Prostheses: a Retrospective Case Series Study with 1-Year Follow-Up

Background: The aim was to evaluate the influence of axial abutment height, abutment angulation, angulated abutment side and implant site on peri-implant marginal bone loss and marginal bone remodeling after 1 year of follow-up in immediate loading implant-supported full-arch fixed dental prostheses.Methods: A retrospective analysis was conducted of patients treated with immediate loading implant-supported full-arch fixed dental prostheses.The retrieved data were: sex, age, implant number, implant length, abutment height, abutment angulation (axial or angulated), implant site (maxilla or mandibular), implant failure and periimplant marginal bone level changes.The marginal bone loss and marginal bone remodeling were evaluated after 6 and 12 months of functional loading trough orthopantomographies.The differences were calculated for axial abutment height (2 vs. 3 mm), abutment angulation for the whole sample and specifically within 3 mm abutments (axial vs. angulated), angulated abutment side (mesial vs. distal) and implant site (maxilla or mandible).The t-test were used for statistical analysis, the level of significance (P≤0.05) was stablished.Results: Seventeen patients (mean age, 65 years) with a total of 87 dental implants were included.No implant failed.The mean marginal bone loss was -0.24 [0.89 standard deviation (SD)] mm at 6 months and -0.51 (0.26 SD) mm at 12 months.No significant differences were observed in marginal bone changes neither between 2-and 3-mm axial abutments nor between axial and angulated abutment.Marginal bone changes were higher in 2-mm axial abutments than in 3-mm ones, in angulated abutment than in axial ones, and in mesial sites of angulated abutments than distal sites, but all these differences were non-significant.Considering only 3-mm high abutments, significantly higher marginal bone loss was detected after 12 months and more bone remodeling after 6 months for angulated abutments than for axial ones.All marginal bone changes were higher in maxillary implants, but only for marginal bone loss after 12 months were differences statistically significant.Conclusions: Within the limitations of this study, 3-mm angulated abutments had significantly more marginal bone loss after 12 months and more bone remodeling after 6 months than 3 mm axial ones.Axial abutment height and angulated abutment side did not significantly influence marginal bone loss nor bone remodeling.Maxillary implants showed significantly more marginal bone loss than mandibular implants after 1 year of functional loading.More clinical studies with better design and longer follow-up are necessary to address this topic.