## 4 Discussion  
The geometry of the implants is one of the fundamental parameters to be considered in the clinical picture [32]. In this regard, finite element analysis is a powerful means to study the stresses and possible problems that could lead to implant failure. Some studies have focused on the influence of the length [1] of the implant in relation to the stress distribution; it has been reported that the best range of lengths, which corresponded approximately to the true length of the roots of the teeth, was suggested to be in the range of 8 mm and 13 mm [9; 33; 34; 35]. This criterion was met by the implant object of the present investigation, which has a wheelbase of about 0.8 mm. Similarly, the studies concerning the geometry of the helix showed a close correlation between the same stress and the distribution of stress around the implant. A decrease in the thread pitch of the implant could positively influence the stability of the implant. One of the technical measures concerning the implant geometry, also used on the implants under investigation, was the addition of helixes or micro-helixes up to the crestal module that provided a potentially positive contribution to the implant-bone adhesion as well as to the conservation of marginal bone [33; 35; 36]. In general, as previously treated, bone is remodeled constantly to adapt to external stimuli due to the surrounding environment, a phenomenon known as bone homeostasis. Therefore, the implants were designed to maximize the delivery of optimal favorable voltages, minimizing the amount of extreme adverse stress at the implant-bone interface [37; 38]. Hence, these implants have threads that allowed better stability and a greater surface of implant-bone contact. It is, therefore, evident that a pitch of 0.8 mm has a higher resistance to vertical load. In this study, conical implants were used that produce compressive forces (positive for bone remodeling). On the contrary, in cylindrical implants, cutting forces were more developed due to implant damage [39]. In addition, the double thread was more useful for faster insertion than the single thread. Studies have shown that implants with multiple threads (resulting in a lower height) have a higher percentage of the bone-implant interface [40]. In addition, a greater depth of the helix can be an advantage in areas of softer bone and when there was greater occlusal strength due to increased functional surface in contact with bone [35]. In contrast, the decrease in the depth of the filled allows for easier insertion into the denser bone without the need for tapping [41]. The results obtained regarding this localized study of the peri-crestal zone were extremely interesting [42; 43]. Firstly, both implants generated significantly lower stress distributions in the peri-crestal area than the yield stress of the material constituting the abutment (the maximum stress developed in this area was 100 MPa in the face of a yield stress of 860 MPa Ti6 Al4V). This result makes it possible to affirm that both implants will be able to withstand occlusal forces for a considerable life span, which is an excellent result that guarantees the clinical success of the treatment. There were substantial differences concerning the uniformity of stress distribution. The dental implant with zero inclination of the abutment had a very uniform and axisymmetric stress distribution; the stress distribution was, for the same occlusal forces considered in all 3 cases (100 N, 200 N, and 300 N), much lower than the implant distributions with an inclination of 15\({}^{\circ}\)of the abutment. In addition, stresses were distributed gradually over a finite and substantially defined range (for an occlusal force of 100 N stress \(\rightarrow\) range in MPa (18, 25); for an occlusal force of 200 N \(\rightarrow\) stress range in MPa (36, 50); for an occlusal force of 300 N \(\rightarrow\) stress range in MPa (50, 70)). On the other hand, the 15-prong implant had a stress concentration in the peri-crestal area of the implant, meaning localized stress.