Impact of over-contoured restorations on the marginal bone around tissue-level implants: A retrospective radiographic...

The emergence angle (EA) and emergence profile (EP) of implant restoration are critical factors influencing peri-implant health. An EA greater than 30° with a convex EP has been associated with the risk of peri-implantitis in bone-level implants. This study aims to evaluate the impact of crown contour on the marginal bone in tissue-level (TL) implants.

This retrospective study analyzed 200 TL implants in 101 patients. The EAs were categorized into two groups: <40° and ≥40°. The marginal bone level (MBL) was measured radiographically over three time periods: 1-2 years, > 2 up to 5 years, and > 5 years post-restoration. Generalized estimating equation models were used to determine potential factors influencing MBL changes.

A negative relationship was observed between MBL and EA (p < 0.001). After adjusting for confounders, implants with EAs ≥40° had 0.43 mm less MBL change (95% CI: -0.60 mm, -0.25 mm) compared with EAs <40°. EP did not significantly impact MBL differences between groups.

Tissue-level implants with over-contoured restorations with an EA of ≥40° did not negatively impact the MBL, and this finding was statistically significant. The risk indicators of a 30° restorative EA threshold and a convex profile did not apply to TL implants.

The contours of implant crowns are critical factors that influence the health of implants. Wide crown contours with a 30° angle or more and a convex profile have been associated with implant disease. The aim of this study was to evaluate the impact of crown contours on the bone levels around tissue level (TL) implants. This is a retrospective study which analyzed 200 TL implants. The crown contours were evaluated as an angle <40° and ≥40° and concave, convex, and straight crown profiles. The bone level around implant margins (MBL) were measured using radiographs at three time periods: 1-2 years, > 2 up to 5 years, and > 5 years post-restoration. Generalized estimating equation models were used to determine potential factors influencing MBL changes. A negative relationship was observed between MBL and implant angle (p < 0.001). After adjusting for confounders, implants with angles ≥40° had 0.43 mm less MBL change compared with angles <40°. The crown profile did not significantly impact MBL differences between groups. TL implants with over-contoured crowns with angles of ≥40° did not negatively impact the MBL, and this finding was statistically significant. The risk indicators of a 30° crown angle threshold and a convex profile did not apply to TL implants.