## 1 Introduction  
In daily practice, performing direct adhesive restorations in the posterior region is one of the most frequent dental procedures [1; 2; 3]. It is well known that when adhesive restorations are planned, the working area has to be properly isolated and a strict protocol has to be followed for the successful usage of these restorative materials. Today, utilizing rubber dam isolation is highly recommended when treating posterior teeth adhesively [4; 5]. As stated by [PERSON] et al., the lifespan of resin-based composites is longer when rubber dam isolations are used [6] as it keeps away moisture (saliva, sulcus fluid, blood) from the working field, which this way will not compromise the adhesion to dentin [7; 8]. Proper isolation of these teeth is essential, especially in cases of subgingival, extensive cavities or hard tissue deficiencies. In order to safely treat such situations, in 1998 [PERSON] and [PERSON] introduced a technique named \"vertical margin relocation\" (CMR) [9], which was renamed to \"deep margin elevation\" (DME) in 2012 by [PERSON] and [PERSON] [10]. DME is indicated when the isolation of the gingival margin of a Class II interproximal cavity is not straightforward by applying the rubber dam alone as an alternative to performingsurgical gum recontouring (gingivectomy) to expose the covered gingival margin [11]. In these cases, a base of direct resin composite is placed by using a metal interproximal matrix to elevate the existing gingival part, which will later serve as a foundation for the future indirect bonded restoration. As a result of this, the previously subgingivally located margin can be predictably captured by a conventional impression and/or intraoral optical scanning (IOS) [10]. However, the application of rubber dam isolation can be extremely complicated in DME cases for several reasons: (i) the presence of deep carious lesions located subgingivally that interfere with the rubber dam clamp, (ii) difficulties in applying the matrix system and rubber dam on the same tooth, (iii) interference between the clamp and the matrix, (iv) irregular gum line making rubber dam inversion impossible, etc. [12]. Not only can the placement of the rubber dam be problematic but also the selection and application of the appropriate matrix can pose challenges. These situations often require chairside modified matrices (e.g., a greater curve or \"banana-shaped\" matrix) [10] or chairside tailoring of conventional matrices (e.g., the \"matrix-in-a-matrix\" technique) [13], making these cases highly dependent on the operator's skills. Furthermore, proper adaptation of these modified solutions is often challenging and time-consuming, whereas adaptation is of key importance to reach success in these delicate cases. Due to the above-mentioned difficulties, many articles indicate the surgical modification (gingivectomy) of the involved gum area [14; 15; 16]. However, such surgery is often demanding both from the operator's and the patient's side [16]. Whenever biologically possible (without violation of the biological width), the aim would be to solve these situations with proper matrices without correction of the gum. The ideal matrix must provide not only proper sealing at the gingival margin but also an ideal emergence profile to the new restorative margin to facilitate the establishment of the contact point with the future final restoration. As shown by [PERSON] et al., a proper contact point establishment increases the success of indirect restorations with previous DME [17]. The often irregular shape of the interproximal cavity margin before DME can benefit from using an individualized matrix to assist in the DME and the core build-up process. Over the past decade, digital innovation has played a significant role in the advancement of dentistry [18]. The ongoing developments in additive manufacturing (3D printing) and IOS have enabled the design and production of highly accurate dentures [19].