Influence of Angulation in Cervical Prosthetic Emergences Relative to the Gingival Tissue of Teeth Treated under the Biologically Oriented Preparation Technique (BOPT)

Abstract

Background: The objective of this study was to digitally evaluate the effect of the cervical emergence of restorations in terms of gingival tissue volume. Materials and methods: In this study, 31 upper front teeth (from canine to canine) were selected and prepared using the biologically oriented preparation technique (BOPT). Each tooth had undergone a change in its provisional process with different emergence profile angles: 30° and 60°. Each sample was digitalised (STL file) using an intraoral scanner. By using various pieces of manipulation software for STL files, a volumetric analysis protocol was carried out. Changes in gingival thickness and position were measured at the buccal and the lingual positions. Results: By increasing the angulation of the emergence profile to 60°, the gingival thickness increased by 0.255 ± 0.381 mm (p = 0.001; t-test) at buccal and by 0.038 ± 0.381 mm at lingual (p = 0.600; t-test). In relation to the gingival height, at buccal, there is an apical displacement of 0.262 ± 0.246 mm (p = 0.001; t-test), and at lingual, there is an apical displacement of 0.390 ± 0.279 mm (p = 0.001; t-test). It was shown that an increase in the provisional emergence profile angle significantly diminishes the gingival height while significantly increasing gingival thickness. The Pearson’s correlation coefficient, r = 0.636, was moderately high and significant (p = 0.001; Pearson). Conclusions: The soft tissue surrounding the BOPT restored tooth evolved according to the prosthetic emergence angle of the provisional restoration, enabling us to plan for an apico-coronal and bucco-lingual displacement of the gingival tissue prior to the definitive restoration.