## 4 Discussion  
Since the one-piece cylindrical-shaped implant with a transmucosal convergent neck and hyperbolic geometry and the abutment/implant system with sub-crestal straight cylindrical-shaped neck showed significantly different behavior, the null hypothesis was rejected. A progressive crack propagation with fracture of the implant body occurred when the dental implant under mechanical fatigue no longer had the physical endurance to withstand repeated stress loading conditions. To decrease the incidence of negative events, some authors tried to reduce mechanical failure rates by modifying the features of the implant systems under investigation, such as diameter and screw joint design, and/or the shape, length, material, and number of the components [16,17]. Studies suggested that the use of orthodontic mini dental implants (MDI) and small diameter implants (SDI),necessary to achieve skeletal expansion, could lead to complications such as fracture, mucositis and ulceration [18,19]. Even though many other factors, such as different surgical procedures (techniques of drilling in the opposite rotatory direction to conventional drills) or various surgery devices for implant positioning, e.g., electromagnetic instruments (Magnetic mallet(r), Osseootouch, Turbigo, Milano, Italy [[https://www.osseootouch.com/](https://www.osseootouch.com/)]([https://www.osseootouch.com/](https://www.osseootouch.com/))) or piezosurgical devices (Piezosurgery(r)touch, Mectron, Carasco, Italy), (KaVo SONICflex(r) KaVo Italia srl, Genoa, Italy) could affect postimplant osseodesification and, in turn, implant fracture [20]. Implant transmucosal designs were launched as a result of clinical studies attesting that the cresal implant/abutment interface, as well as the type of connections, platforms, and surface properties of the components, had great effects on biological dimensions and the amount of soft tissue inflammation, as well as on the marginal bone levels around implants [21]. As regards transmucosal designs, it was suggested that concave designs might reduce the compression around the healing peri-implant connective tissue and promote cell adhesion [22]. Moreover, in the following phases of healing, a narrow design seemed to reduce marginal bone loss, providing a wider/horizontal space versus the smaller space of the conventional flared transmucosal components [23]. However, very recent review papers suggest there isno evidence for differences in marginal bone loss or implant survival rate between standard and narrow implants [24], or between bone-level and transmucosal dental implants, after a period of follow-up v from 12 to 60 months [25]. Some authors suggest that both ascond surgery, required  
Figure 5: Failure modes in dynamic load test for Prama (**A**) and Premium (**B**). for uncovering a submerged implant, and the connection/reconnection of the healing screw and prosthesis, could be factors that affect healing and stability of the peri-implant environment [26]. Nevertheless, in the absence of definitive evidence attesting whether transmucosal or submerged healing might have a more favorable long-term influence, we must assume similar behavior regarding the stability of the hard and soft peri-implant tissues for both procedures [27, 28]. The present study showed data of two different implant systems from a single manufacturer and compared their load-bearing capacity. Mean results of static fracture resistance tests (excluding those from narrow implants) ranged between 390 N and 434 N and were in line with previous studies describing transmucosal implants with or without a ferrule effect (0.38 cm with UFL from 362 N to 445 N) and standard/wide-diameter implants (0.4 cm or higher with UFL of 565.64 \(\pm\) 185.46 N) [29, 30]. Itisclear from Figure 2 that the transmucosal and equicrestal standard diameter implants behaved differently in the presence of a gradual progressive force, with the transmucosal design showing slightly nonsignificant higher resistance.