## 1 Introduction
On the contrary, those connections which are more resistant to the bacterial leakage, e.g., Cone-Morse and conical ones, could be positioned more apically in relation to the alveolar crest with a very small or no peri-implant bone resorption [13; 14; 15]. Thus, the subcrestal positioning of a Cone-Morse connection could be possible from biological and clinical points of view [13; 14; 15]. This practice could carry significant beneficial implications, mainly from an aesthetic point of view, because it would allow a better prosthetic emergence profile. However, different and controversial results have been reported in the literature by in vitro, animal, and clinical studies, as well as systematic reviews of the literature, about different resorption rates related to implants inserted in equicrestal or subcrestal positions [16; 17; 18; 19; 20; 21; 22; 23; 24; 25; 26; 27; 28; 29; 30; 31; 32]. In recent years, Finite Element Analysis (FEA) studies demonstrated to be extremely useful in evaluating several different aspects of the biomechanical characteristics of dental implants and bone [33; 34]. FEA analysis is a computational simulation technique that uses numerical methods to model and analyze the behavior of an object or structure under load. In case of dental implants, an FEA model can be created to represent the implant, surrounding bone, and gum tissue. The model can be used to simulate loading conditions to which the implant is subjected during chewing and to evaluate the stress and deformation factors generated into the bone and within the implant itself. The Finite Element Method (FEM) can also be used to study the behavior of dental implants based on the depth of dental insertion into the bone tissue and is also able to provide information about the load distribution between the implant and the surrounding bone at different insertion depths. This may help identifying areas of increased strain or overload that could affect the stability and durability of the system [35; 36; 37; 38; 39; 40]. Furthermore, FEA studies could help assess how insertion depth affects the primary stability of the implant, thereby identifying the ideal depth for achieving the optimal implant anchorage in bone tissue, since primary stability is considered a critical factor for successful bone integration. In this context, the FEA could also estimate the surrounding bone response to the implant insertion at different depths. This may provide simulated indications of possible bone resorption or increase in bone density, which may occur over time due to the interaction between implant and bone [40; 41; 42]. This information is important to ensure that neither the implant nor the bone would be subjected to excessive stresses that could lead to implant failure or complications. It is important to note that FEA is a numerical simulation tool, and its predictions depend on the accuracy of data and material properties used in the model. Therefore, FEA studies should be considered as a support for the interpretation of the results and further clinical decisions should be made basing on an overall assessment, also taking into account other patient-specific clinical and radiographic considerations [33; 34; 35; 36; 37; 38; 39; 40; 41; 42]. For that reason, this study has been conducted to perform a FEA survey of implants presenting a Cone-Morse implant-abutment assembly, inserted in different positions relative to the alveolar crest. The hypothesis that is carried out is related to the non-dependence of bone thickness with the depth of insertion of the implant.