Volume of unsupported peri-implant soft tissue over time: A cross-sectional observation study.

STATEMENT OF PROBLEM: Supraimplant emergence profile changes have revealed that, when not supported, peri-implant soft tissue collapses. However, this phenomenon has not been described qualitatively and quantitatively in 3 dimensions. PURPOSE: The purpose of this cross-sectional clinical study was to analyze changes in the supraimplant emergence profile digitally over time when the peri-implant soft tissue was not supported. MATERIAL AND METHODS: A data set consisting of 16 participants with 16 implants was used. After removal of the healing abutment or the interim restoration, 4 intraoral optical impressions were made successively on the patient to record the supraimplant emergence profile at 4 different times: 0 second (T(0)), 30 seconds (T(0.5 min)), 2 minutes (T(2 min)), and 5 minutes (T(5 min)). The supraimplant emergence profile surfaces obtained were closed with a 3D meshing software program (Meshmixer) to obtain the volume of the supraimplant emergence profile at each time. The reference volume at T(0) (Vol T(0)) corresponded to the volume created during the mucosal healing phase, which, theoretically, should be preserved for the fabrication of the definitive crown. The different volumes (Vol T(0.5 min), Vol T(2 min), and Vol T(5 min)) were compared with Vol T(0) to analyze the volumetric changes, kinetics, and topography of this variation by using a 3D visualization and analysis software program (Avizo). A nonparametric Wilcoxon test for paired samples was used for comparison. RESULTS: The supraimplant emergence profile volume decreased by an average of 5% at 30 seconds (P<.001), 10% at 2 minutes (P<.001), and 14% at 5 minutes (P<.001). CONCLUSIONS: The supraimplant emergence profile collapsed significantly in 3D when unsupported for 30 seconds or more.