Marginal Bone Loss in Posterior Implants Placed at Different Levels and Different Prosthetic Designs: A Retrospective Study With a Minimum of 1-Year Follow-Up.

Various factors influence marginal bone loss after implant placement. This study explored the association between marginal bone loss and posterior implants positioned at different bone levels. Computer records and radiographs of patients with at least 2 adjacent implants were retrieved. Cases were categorized into nonsplinted prosthesis and splinted prosthesis groups. Radiographic measurements were conducted at the time of abutment placement (T0), 1-3 years follow-up (T1), and the last visit (T2), measuring the vertical distance between adjacent implants. Multilevel linear regression models using generalized estimating equations were employed, with a significance level set at 5% (α = 0.05). Fifty-six patient records were included, comprising 120 implants: 84 nonsplinted (70%) and 36 splinted (30%). In the nonsplinted group, marginal bone loss progression significantly depended on crestal height differences. For the mesial sides of posterior implants, marginal bone loss measured 1.0 ± 0.6 mm from T0 to T1, 2.4 ± 1.1 mm from T1 to T2, and 3.4 ± 1.2 mm from T0 to T2. Similarly, the distal sides of the most anteriorly placed implant exhibited marginal bone loss of 1.0 ± 0.7 mm from T0 to T1, 2.4 ± 1.0 mm from T1 to T2, and 3.5 ± 1.2 mm from T0 to T2. Nonsplinted implants demonstrated a higher progression of marginal bone loss. This study suggests that nonsplinted implants may lead to a more pronounced progression of marginal bone loss, particularly concerning crestal height differences, underscoring the need for further research.