## 2 Materials and Methods
### Fabrication of the Restorations  
To fabricate the CM and CMc frameworks, the specimens were scanned and digitized with the Lava Scan ST (3M ESPE, Seefeld, Germany), and the frameworks were designed using CAD software (DWOS version 7.0; Dental Wings, Montreal, QC, Canada). The wax patterns were made with the Projet 1200 3D printer (3D Systems, Rock Hill, SC, USA) and invested with phosphate graphite-free investment plaster (Vestofix; DFS Diamond GmbH, Riedenburg, Germany). The casting was performed using induction and a centrifugal vacuum-casting machine (MIE-200C/R; Ordenta, Arganda del Rey, Spain) under vacuum pressure of 580 mmHg, at a melting temperature of 1480 \({}^{\circ}\)C. After casting, the samples were cleaned with water steam and sandblasted with aluminum-oxide particles (50 \(\upmu\)m) under 50 N/cm\({}^{2}\) pressure (EXTRAmatic 9040; Kavo Dental GmbH, Biberach, Germany). To prepare the LS and LSC frameworks, the scanning and design process was similar to the CM and CMc groups. The CAD design file was transferred to a DMLS unit (PM 100 Dental; Phenix Systems, Clermont-Ferrand, France), and the laser sintering process was performed by building 20 mm layers of alloy powders from the occlusal surface to the margins by applying a Yb-fiber laser at 1650 \({}^{\circ}\)C under an argon atmosphere. All the frameworks were cleaned and sandblasted in the same manner as the casted frameworks. To fabricate the SM and SMc frameworks, the specimens were scanned (Ceramill Map400; [PERSON], Koblach, Austria), and the data were entered into specific design software (Ceramill Mind; [PERSON]). To compensate for the post-sintering shrinkage, the design was enlarged by 11%. These data were pre-set in the software. The frameworks were manufactured from pre-sintered Co-Cr discs in a milling unit (Ceramill Motion 2; [PERSON]). Then, the specimens were placed in a sintering tray (Ceramill Argovert; [PERSON]) and introduced into a sintering furnace (Ceramill Algothem 2; [PERSON]) at 1.30 \({}^{\circ}\)C under an argon atmosphere to prevent oxidation. All the frameworks were cleaned and sandblasted in the same manner as the casted frameworks. The manufacturing process for the HM and HMc frameworks also began with scanning the specimens (3 Shape D750; 3 Shape Dental System, Copenhagen, Denmark) and designing the copings by the specific software (Molder Builder; 3 Shape Dental System). Two sintered Co-Cr discs were inserted in the warehouse (PH 2/120 SAUER; DGM Mori, Stipshausen, Germany) of the milling unit (Ultrasonic 10 linear; DMG Mori, Bielefeld, Germany) and machining was carried out. All the 3D framework designs were done by experienced technicians with the same parameters: 0.5 mm wall-thickness, internal cement space of 50 \(\upmu\)m, a premolar shape pontic, and a connector area of 9 mm\({}^{2}\) (3 mm \(\times\) 3 mm). All the frameworks were cleaned and sandblasted in the same manner as the casted frameworks  
The frameworks were luted onto their corresponding specimen using conventional glass-ionomer cement (Ketac-Cem EasyMix; 3 M ESPE), mixed following the manufacturer's instructions, at room temperature (18-24 \({}^{\circ}\)C) and relative humidity (50 \(\pm\) 10%).