## 4 Discussion  
This study developed a novel friction-based lateral screw-retained method approach by designing a universal coping and surface treatment for an existing abutment. This approach to the novel retention method can be used on most single-implant restorations with a flat surface (in this case, an anti-rotation feature for Dentium), with a simple manufacturing procedure carried out on the coping to give access to the lateral screw and surface treatment performed on the flat surface of the abutment to increase the surface roughness. With this coping, the retrievability of screw-retained implants can be achieved at the same time. Although, currently, this coping design is limited, this design structure can be further developed to provide better support. A study by [PERSON] et al. shows that the maximum fracture resistance strength of porcelain in porcelain-fused-to-metal (PFM) crowns highly depends on its metal structure/substructure design [48]. Sandblasting is carried out in order to increase static friction, which can lead to stronger retention. Sandblasting is performed to create irregularity in the titanium surface of the abutment, which increases the surface roughness [49]. Surface roughness is related to the friction coefficient, and a higher friction coefficient could increase the retention capability of this retention method. Sandblasting was chosen because it is one of the easiest and most inexpensive methods of surface treatment [50], which increases the possibility of this method being replicated and used around the world since it does not need any specific abutment or implant that is manufactured. The result of this study also demonstrates that it can be implemented by modifying the existing surface of the abutment. The results of sandblasting using various particle sizes show a positive correlation between the particle size and the surface roughness. A larger particle size results in a higher surface roughness of the object's surface. This correlation is similar to that of a study by [PERSON] and [PERSON], which also uses various Al\({}_{2}\)O\({}_{3}\) particle sizes [34]. In this study, the highest surface roughness was shown by SB686 T200 (0.67 \(\pm\) 0.04 \(\upmu\)m), which was also significantly higher compared to other groups (\(p\) < 0.01), and the untreated surface of the abutment (0.04 \(\pm\) 0.002 \(\upmu\)m) had the lowest surface roughness (R\({}_{\text{a}}\)), which was also significantly lower compared to other groups (\(p\) < 0.01). However, the result also shows that groups SB102 T200 and SB254 T200 are insignificantly different from each other, but SB254 T200, which has a larger particle size, shows a higher average of surface roughness. The result of this experiment also shows that surface roughness mainly has a positive correlation with the retention force, which confirms the positive correlation between the surface roughness and the static friction coefficient. Though NS groups show a higher retention force than that of SB63 T200, it is insignificant, and it shows that within that surface  
Figure 11: (**a**) Cement-retained and (**b**) lateral screw-retained failure mode. roughness conditions, the retention is mainly affected by the tightening torque instead of friction between the lateral screw and abutment. In this study, the highest retention force was also shown by groups with the highest surface roughness (SB686 T200), and the lowest retention force was shown by both SB63 T200 and NS groups, which also have low surface roughness. A positive correlation between the surface roughness and static friction opens the possibility of using other surface treatment options to increase the surface roughness in the abutment's flat surface, thus increasing the versatility of this method. Other surface treatments that can be used as a strategy to increase the surface roughness are laser etching, acid etching, ion implantation, sputtering, and other combinations of several surface treatment methods such as SLA, which combines sandblasting using large grit and acid etching [51].