28/12/2023
...and just before 2023 was about to cut the finish line, an interesting study on the implant supracrestal complex design was just published in JPD from a group in Yonsei University (Han et al 2023). The study measures angles of the abutment/prosthesis and relates them to changes of the marginal bone level. The measurements use 2D periapical radiographs, but moving away from subjective tangent lines and follow a "plane and point" reproducible definition of angles, similar to our 2023 paper in CEDR. They measure 3 angles, one for each vertical millimetre for the first 3 mm of the abutment.
🎯Maybe not surprisingly, they found that its the angle at the first and second mm which really relates with increased marginal bone loss, not the entire contour and not the top 3rd mm from the bone margin. The cut-off points they reported were between 28-34 degrees for the angle defined by first mm range, and 20-33 degrees for the angle by the 2nd mm range. This is what we would describe as the “Deep Angle”, which in our study we defined at the 1.5 mm distance from the implant platform, somewhere in-between the measurements in this study. Also they very wisely avoided the term “emergence angles”, as the true point of emergence is not visible in periapical radiographs.
😍 I think we have made true progress towards methods which can now quantify more precisely and reproducibly the elements of the prosthetic design, while at the same time shed light in its impact to the clinical outcomes. At the same time, it becomes apparent that we have different “regions” in the implant supracrestal complex that cannot be assessed with one single measure, angle or descriptor. The Deep angle seems to be what determines the early marginal bone loss or remodelling, while the Mucosal Emergence angle is what relates to inflammation! These two features might be at times 2mm apart, but it's a whole different process they define!
Before the year ends, have a look at the study by Jin-Won Han et al in JPD 2023!
https://www.thejpd.org/article/S0022-3913(23)00780-1/fulltext