## 1 Introduction  
Modern implants in dentistry, with proper connection, have a success rate of 97.0% throughout a 10-year interval [1]. This long-term success of dental implants in bone is achieved when osseointegration occurs [2]. This can be expected when following the correct indications for dental implants [3]. Because of the high success rate, there is an increased demand for dental implants in daily practice. It is expected that the prevalence of dental implants will increase from 5.7% in 2015 to possibly 23% in 2026 [4].  
Despite the high success rate, osseointegration can also be impeded by inflammation and infection surrounding the implant in a process named peri-implantitis [5]. This inflammation can lead to the loss of supporting bone and is successive and progressive [6]. Peri-implantitis can be caused by both biological and mechanical factors. Mechanical factors, such as a supra structure with partial marginal fit and overloads, can be risk factors for developing peri-implantitis [7]. They may be associated with a limitation in proper oral hygiene, which assists in developing peri-implantitis [8].  
Due to several implant companies, there are a lot of designs and approaches to consider in the contact between abutments and implants. Previous literature showed that the implant-abutment joint has an impact on the mucosal integration around implants and affects the risk of developing peri-implantitis in the future [9], due to having a significant role in technical and biological complications [10].  
Over time, different connection designs have been developed, each possessing distinct mechanical, biological, and esthetic attributes aimed at preserving the stability of the implant-prosthesis interface. However, fundamentally, two major groups of geometries exist: internal and external connections [11]. External connections feature an external hexagon on the implant platform. Internal connections can be commonly categorized into internal hexagon, internal octagon, and Morse taper connections, with the latter currently experiencing widespread utilization due to optimal sealing and better load distribution [12].  
Despite the advantages of Morse taper implants, there is a rising occurrence of complications, including mechanical issues and peri-implantitis. Similarly to other mechanical structures, implants are susceptible to fracture with prolonged usage, and an improper partial implant-abutment joint is one of the many factors that can facilitate its occurrence [13]. Remarkably, this concern is rarely acknowledged or discussed in the literature [14]. This can lead to problems, like crown fractures, peri-implantitis, abutment-screw loosening, implant fracture, and other outcomes that could be avoided if not for the lack of data about the abutment joint in terms of stress [15].  
One of the tools to study dental implants is finite-element analysis (FEA). Finite-element analysis stands as a research instrument for mechanical analyses within biological research. This methodology calculates mechanical responses with the aid of modeling intricate structures and their characteristics [16]. This method is crucial for predicting the performance of both implant materials and bone structures [17]. It is possible to investigate implant-supported restorations, facilitating the assessment of stress distribution and the identification of critical geometries that could lead to clinical failures [18].  
Therefore, the purpose of this in silico study was to investigate the effect of implant-abutment contact surfaces on the stress generation of Morse taper implants under oblique loading. The hypothesis of this study was that there is no difference between Bone-Level and Tissue-Level implants in terms of stress distribution, regardless of the number of contact surfaces between implant and abutment.