## 2 Materials and Methods  
This laboratory study included 60 specimens, divided into four study groups (A, B, C, D), with 15 samples each. Group A consisted of suprastructures, made of monolithic zirconia implant crown and titanium custom abutment with vertical marginal design. Group B included suprastructures, made of monolithic lithium disilicate implant crown and titanium custom abutment with vertical marginal design. Group C had suprastructures, made of monolithic zirconia implant crown and titanium custom abutment with chamfer marginal design, and Group D was suprastructures, made of monolithic lithium disilicate implant crown and titanium custom abutment with chamfer marginal design. Materials used in this research are displayed in Table 1.  
The sample size was computed using SigmaPlot 15.0 software (Systat Software, Inc., San Jose, CA, USA). The sample size was determined in accordance with prior research that investigated the mechanical performance of implant suprastructures under cyclic loading conditions [23; 24; 25; 26]. All samples with chamfer and vertical margin design were fabricated through digital workflow. Study model of maxilla with 4.5 mm diameter implant TSV (Zimmer Biomet, Warsaw, IN, USA), placed in the area upper first right molar, was scanned with intraoral scanner iTero Element intraoral scanner (Align Technology, San Jose, CA, USA). Stereolithographic image was imported in software for virtual design of prosthetic constructions ExoCad software v.3.2 Elefsina (GmbH, Darmstadt, Germany), where monolithic crowns and customized titanium abutments were designed according to their group assignment. Each customized abutment was designed as a cut back of the monolithic crown, which has the same design in each test group. Custom abutments from Groups A and B were planned with vertical margin design and concave emergence profile, following the concept for biologic-oriented preparation technique (BOPT) of [PERSON], and these from Groups C and D--with subgingival chamfer margin design and concave emergence profile. All crowns were constructed with standard wall thickness, which meets the manufacturer recommendations for the specific material (zirconium dioxide or lithium disilicate)--minimal thickness--1.5 mm, not more than 2.6 mm. Customized abutments were fabricated from titanium blanks GenTek(tm) Pre-milled Abutment Blanks (Zimmer Biomet, Warsaw, IN, USA) in inLab MC X5 milling machine (Dentsply Sirona, Charlotte, NC, USA). Monolithic zirconia crowns were milled in the same device and these of lithium disilicate were produced in inLab MC XL machine (Dentsply Sirona, Charlotte, NC, USA). Crystallization of crowns from group B and D was conducted in furnace Programat P300 (Ivoclar Vivadent, Shaan, Liechtenstein), and sintering of groups A and C--in Zirconmaster S (VOP Ltd., Sofia, Bulgaria), followed by glazing with IPS Ivocolar Glaze Paste (Ivoclar Vivadent, Schaan, Liechtenstein). Cementation of the crowns to the abutments were performed according to the manufacturers' prescriptions. The sample groups differed in the type of abutment preparation and the material of the monolithic crown (Figure 1). \begin{table}
\begin{tabular}{l l} \hline \hline
**Materials** & **Study Groups** \\ \hline Titanium Alloy Blanks GenTek(tm) Pre-Milled Abutment Blank (Zimmer & \\ Biomet, Warsaw, IN, USA), grade 5 titanium & A, B, C, D \\ \hline Zirconium Dioxide Katana (Kuraray Noritake, Tokyo, Japan) & A, C \\ \hline Lithium Disilicate IPS e.max CAD (IvoclarVivadent, Schaan, Liechtenstein) & B, D \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Materials used for fabrication of implant suprastructures. The samples were immersed in distilled water at 37 \({}^{\circ}\)C for 24 h before undergoing testing. Each sample was screw-retained to an implant and fixed into the holder of computer controlled 2-axis machine that simulated masticatory movements, Chewing Simulator CS-4 (SD-Mechatronik, Westerham, Germany) [27] by polymethyl methacrylate (Figure 2).