## 1 Introduction  
Implants have become a common treatment option for missing teeth, especially after reports of the clinical success of osseointegration [1]. One of the reasons for the clinical success of implants is related to the marginal gap between the restoration and the implant abtument, which is considered an important factor in prosthodontics [2]. Poor internal fit can lead to a thicker cement layer, which may influence the stability of dental restoration and lead to bacterial penetration along the implant abtument [3, 4]. Studies have shown that an accumulation of bacterial plaque on the margins of the restoration and between the parts of the implant may contribute to bacterial colonization on the abtument interface [5] This may lead to chronic inflammatory infiltrates, increased marginal bone loss, and implant failure in advanced cases [6]. Therefore, the marginal abtument-prosthetic misfit is an important issue in implant rehabilitation. The term \"fit\" has been mentioned abundantly in the literature. The different sites between the restoration and the tooth or implant abtument can be defined as internal gap, marginal gap, vertical gap, horizontal gap, etc. [3]. [PERSON] et al. defined two terms in his study: the marginal discrepancy (MD) and the absolute marginal discrepancy (AMD), which are meaningful factors in the present study [3]. The MD or the vertical value is measured from the cervical margin of the casting to the preparation margin, while the AMD is measured from the cavosurface of the preparation to the cervical margin of the cast. It is defined as the angular combination of the MD and the extension error (Figure 1) [3,4]. The closeness of the clearance between an implant abutment and the prosthesis indicates the precision of fit. The MD represents the cemented surface which can be dissolved as result of exposure to the oral environment, while the AMD increases plaque accumulation [4]. Therefore, the main goal is to minimize the two marginal misfits, MD and AMD, and decrease bacterial colonization while keeping the surface clean and without roughness due to residual cement. There is no consensus regarding a clinically acceptable misfit. Several studies examined the MD value between CAD/CAM manufacturing and preparation. They reported that the MD of CAD/CAM systems ranged from 50 \(\upmu\)m to 100 \(\upmu\)m and a 90 \(\upmu\)m MD was clinically acceptable [4,7, 8, 9, 10]. The MD values were measured using light microscopy, a scanning electron microscope (SEM), and epoxy replicas [8, 9, 10]. Some studies have shown that a CAD/CAM implant fit is superior to that of conventional cast frameworks [11], although a few in vitro studies showed lower values of misfit for the conventional method than those of CAD/CAM systems [11]. [PERSON] et al. compared the marginal fit between metal ceramic, press on metal, and zirconia restorations. He found that mean MD measurements for press on metal ceramic restoration (81.6 \(\upmu\)m \(\pm\) 18.3 \(\upmu\)m) were lower than mean values (98.2 \(\upmu\)m \(\pm\) 34.6 \(\upmu\)m) in CAD/CAM zirconia restorations [12]. In a study by [PERSON] et al., the CAD/CAM group had significantly higher MD mean values (80.58 \(\upmu\)m) than the coping milling (Zirkonzahn) and base metal alloy groups (50.33 \(\upmu\)m and 42.27 \(\upmu\)m), respectively [13]. These results support the study by [PERSON] and [PERSON], who reported that crowns and abutments fabricated by CAD/CAM demonstrate similar survival rates as conventionally fabricated prostheses [14]. In an integrative review, the clinically acceptable vertical abutment prosthetic misfit in implant-supported prostheses, which is more relevant to the current study, ranged from 50 to 160 \(\upmu\)m [15]. Although 100 \(\upmu\)m is considered an acceptable mean value for vertical misfit, many studies included in the review reported lower mean values. Furthermore, CAD/CAM techniques resulted in lower mean vertical misfit values (less than 120 \(\upmu\)m) compared to the casting technique in this study [15].