The 3D emergence profile on implant-supported restorations: A method for evaluating restorative angles

Statement of ProblemEmerging evidence indicates that the emergence profile and subsequent restorative angle play a crucial role in clinical outcomes and can potentially affect the development and progression of peri-implant diseases. However, the traditional evaluation of the emergence profile and angle has been limited to mesial and distal sites using periapical x-rays, without considering the buccal sites. PurposeTo describe a novel 3D method to estimate the emergence profile and restorative angles around single implant-supported crowns including buccal sites. Materials and MethodsA total of 30 implant-supported crowns (11 molars, 8 premolars, 8 central incisors and 1 canine) were extra-orally scanned using an intraoral scanner and the STL files produced were imported into a 3D software. The crown/abutment interface of each crown was delineated, and apico-coronal lines were automatically drawn following the shape of the crown. Three reference points were defined on the apico-coronal lines at the transition edge of the biological (BC) and the esthetic zone (EC) and the resulting angles were then calculated. The reliability of the measurements (2D and 3D) were assessed using the intraclass correlation coefficient (ICC). ResultsIn anterior restorations, the mean angle of the esthetic zone amounted to 162 +/- 14 degrees at mesial sites, to 140 +/- 10 degrees at buccal sites and to 163 +/- 11 degrees at distal sites. The corresponding angles at the biological zones, amounted to 155 +/- 13 degrees at mesial sites, 139 +/- 15 degrees at buccal sites and 157 +/- 5 degrees at distal sites. In posterior restorations, the mean angle of the esthetic zone amounted to 162 +/- 12 degrees at mesial sites, to 157 +/- 13 at buccal sites and to 162 +/- 11 at distal sites. The corresponding angles at the biological zone, amounted to 158 +/- 8 at mesial sites, 150 +/- 15 degrees at buccal sites and 156 +/- 10 at distal sites. The ICC for all measurements ranged between 0.77 and 0.99 indicating a good intra-examiner reliability. ConclusionWithin the limitations of the present study, the 3D analysis seems to be a reliable and applicable method for the quantitative evaluation of the emergence profile in daily practice. Future randomized clinical trials are needed to assess whether a 3D analysis with the ensuing the emergence profile serves as a predictor for clinical outcomes. Clinical SignificanceThe development and implementation of a 3D workflow will provide technicians and dentists with the ability to assess the restorative angle of implant-supported restorations during the provisional phase and the final restoration. This approach may help achieve an aesthetically pleasing restoration while minimizing potential clinical complications.