Regarding the effect of direction of loading on induced microstrains, it was shown that changing the position of occlusal loading had a considerable effect on the amount of distribution of stresses where axial loading generated even distribution of load around the implant in comparison to off-axial loading where stresses were more pronounced in the area of load application. This might be due to the increase of the horizontal component of the applied load which was stated to generate an increase in the moment and eventually an increase in the compressive load on the side of applied force, to a level higher than the compressive load generated by only the vertical component of the force generated by axial loading [12]. Yet, regardless of other variables, there was no statistically significant difference between axial and off-axial loads. Regarding the off-axial in comparison to axial loading, a particularly high risk of traumatic overload occurred with the standard single-unit implant restoration because the restoration itself is usually wider than the implant, creating the potential for a cantilever effect with high bending moments, in off-axial loading [35]. So the loaded side implants bear more stresses on its distal part due to bending moments of the cantilever on the restorations which in turn transfer more stresses to the peri-implant bone at this side [36]. Flanagan [37] stated that mini implant smaller surface area and volume places more force per square millimeter against the encasing bone than larger diameter implants. So, mini implants may be best used in multiples to resist off-axial forces to prevent metal fatigue and fracture. According to Kheiralla and Younis [12], off-axial loading of single mini implant (3-mm diameter) supporting single molar crown induced mean microstrains value higher than the physiologic limit while in this study, the mean microstrain value of double mini implant supporting metal and Lava Ultimate crowns under off-axial loading were within the physiologic limit (890.8 μɛ and 1137.6 μɛ, respectively).This is in accordance with Balshi et al. [38] who stated that two implants can basically eliminate MD bending and that this situation can enable double implants to induce even less load magnification than a wide diameter implant. In this study, although short-wide implants showed mean peri-implant microstrains under axial loading higher than off-axial loading, axial loading of short-wide implant resulted in compression microstrains in all surfaces in case of metal and lava ultimate crowns, indicating that microstrains were distributed almost equally on all surfaces under both axial and off-axial loading. In this study, it was noticed that short-wide implant showed lowest off-axial loading in comparison with standard and double mini implants. Javris [39] emphasized the biomechanical advantage of wide-diameter implants, particularly in reducing the magnitude of stress delivered to the various parts of the implant. The diameter of the implant is related to the bending fracture resistance or moment of interia, and the increase in diameter decreases the risk of fracture to the power of four, provided all other geometric features remain the same. As a result, wider diameter implants may be used when offset loads (cantilevers) or greater stress conditions (i.e., parafunction, molar regions) exist. Moreover, this feature allows better distribution of occlusal forces [33,41,, 40–42]. Rangert [43] considers that wide, single implants are the best choice to resist lateral forces. An increased width of an implant may decrease offset loads, thus increasing the amount of the implant-bone interface placed under compressive loads [34].