## 1 Introduction  
The digital work-flow in dentistry has increased in recent years due to technological advances in intraoral scanners and software. Intraoral scanners can digitalise the oral cavity and create a virtual three-dimensional model; the individual images obtained are stitched together with other ones, and the result is a mesh of points that creates a three-dimensional (3D) virtual model of the object being scanned [1,2].  
Recently, superimposition and comparisons of 3D digital images have been used to measure the volume and contour changes in various fields of dentistry. This process can be described as an objective method to quantify three-dimensional changes and achieve a precise measurement and volumetric reconstruction [3].  
A healthy relationship between dental restorations and the periodontitis is of fundamental importance to ensure clinical success in both the function and esthetic harmony of full coverage restorations. One of the most common complications derived from fixed prostheses is gingival recession, which constitutes an important clinical concern. This problem is largely associated with the iatrogenic effects produced during dental preparation or as a result of a poor prosthetic fit; it will compromise esthetics, and thus is particularly detrimental in the anterior region. Subgingival horizontal preparations have been conventionally indicated in cases of aesthetic demand; however, they are related to adverse periodontal reactions, such as inflammation, bleeding, deeper probing, and recession [4].  
The biologically oriented preparation technique (BOPT) is a protocol whereby vertical preparation eliminates the anatomical emergence profile of the crown corresponding to the cement-enamel union (CEJ) to create a new emergence with a prosthesis that imitates the natural tooth at the very moment it is positioned. The protocol for the manufacture of the provisional prosthesis is of key significance as it determines the new emergence context, placing it at different levels within the gingival sulcus. This allows the surrounding soft tissue to adjust its form and position to accommodate the new prosthetic profile, thereby guiding the healing, the reinsertion, and the thickening of the gingival tissue [4; 5; 6; 7; 8].  
It has been suggested that thicker soft tissue biotypes are associated with less tissue recession, higher crestal bone levels, and better aesthetics. A thin tissue biotype has been shown to be more prone to tissue recession. Furthermore, there is evidence that thick soft tissue may be protective against crestal bone loss. As a result of these findings, many authors have recommended the routine use of connective tissue grafts to thicken the labial soft tissue to >2 mm [9; 10]. This is an important clinical finding because, traditionally, soft tissue grafts have been used to enhance the thin soft tissue, to thicken the buccal bone and crestal labial soft-tissue around teeth and implants, and vice-versa [11].  
The authors who have published on the BOPT technique have detected a clinical thickening of the gingival tissue and a soft tissue stability improvement around dental restorations [4; 7; 8], but the measurement mechanisms used by these authors have been subject to variation. It was also noted by these authors that this technique enables gingival tissue to be displaced in an apico-coronal and bucco-lingual direction, thereby modifying the cervical emergence of the tooth-supported prosthesis.  
The objective of this study was to digitally evaluate the effects of cervical emergence in the gingival tissue volume and thereby quantify and objectively outline the modifications taking place in the gums. The established hypothesis was that a change in the angulation of the cervical emergence of the BOPT prosthesis would modify the incisal position of the gingival margin and the thickness of the adjacent gingiva.