## 4 Discussion  
The results analysis highlighted Group A--suprastructures made of customized titanium abutments with vertical margin design and monolithic zirconia crowns as the most resistant to compressive forces (4411 MPa). Group D (suprastructures made of customized titanium abutments with chamfer margin design and monolithic lithium disilicate crowns) was with lowest values (1864 MPa)--twice than Group A. Samples were fractured as expected for ceramic materials, with vertical fractures. No abutment or screw fracture was observed. Data revealed better performance of customized abutments with vertical margin design, than the chamfer one. This state was supported by the results from Group B, which had lower results than Group A, but higher than Groups C and D (customized abutments with chamfer design). These findings correspond to the research of [PERSON] et al. [29], who claim that abutments with vertical margin design have better mechanical characteristics.  
Comparison between groups, according to the material, used for crown fabrication, points out statistically significant compressive behavior of zirconia monolithic crowns, than lithium disilicate, which share the opinion of [PERSON] et al. [30], [PERSON] et al. [31], and [PERSON] et al. [32], but it is controversial to the state of [PERSON] et al. for good longevity of lithium disilicate prosthetic constructions [33].  
This tendency becomes more pronounced in zirconia crowns, cemented to abutments with vertical margin design. [PERSON] et al. [34] also support the thesis of the higher mechanical resistance of zirconia crowns, but do not analyze the significance of the abutment's marginal design.  
[PERSON] et al. [35] suggest that biologically oriented margin design in implant supported constructions has several advantages, such as better marginal adaptation of the crown after cementation and minimal microgap in comparison with chamfer margin design.  
Our study revealed that chamfer margin design provides good peri-implant soft tissue support, but bigger abutment reduces the space for the prosthetic construction, which may lead to its lower mechanical resistance. This proves the statement that crowns are weak points of implant suprastructures and that abutments durability is ensured. All this supports better longevity of crown abutments with vertical preparation.  
Studies with same experimental set up, but on natural teeth abutments, report similar results as our findings [36]. This supports the thesis of greater mechanical stability of vertical preparation, but the need for more in-depth studies with a larger number of test samples remains.  
The findings have restricted clinical significance due to the sample number and their laboratory characteristics, highlighting the need for further in vivo research. This study was conducted in dry environment. However, the specimens were stored in water until  
\begin{table}
\begin{tabular}{c c c c c} \hline \hline \multirow{2}{*}{**Differences Between**} & \multicolumn{2}{c}{**Mean**} & \multirow{2}{*}{_p_**-Value**} & \multirow{2}{*}{**95\% CI Lower**} & \multirow{2}{*}{**95\% CI Upper**} \\  & & **Difference** & & & \\ \hline Group A & Group B & 1096.40 & 0.00 & 616.68 & 1576.12 \\ \hline Group A & Group C & 1280.47 & 0.00 & 512.46 & 2048.47 \\ \hline Group A & Group D & 2546.80 & 0.00 & 2026.79 & 3066.81 \\ \hline Group B & Group C &  
testing, it is essential to determine whether, under the biodynamic balance of the oral cavity, the analyzed materials would maintain similar mechanical properties over the long term.