## 1 Introduction  
With the development of 3D printing, its applications are increasing. The technology is ideal both in industry, where it is used to print designs and prototypes, among other things, and in less obvious fields such as medicine. It is possible to create teaching aids in this way, such as anatomical models, or elements intended for direct permanent contact with the human body. The use of 3D printing in medicine makes it possible to produce individual pieces in a short period of time, minimizing production costs [1]. One of the main fields of medicine where 3D printing has found its application is dentistry. The possibilities offered by this technique have made the process of creating dental restorations more precise, efficient, and customized for even the most demanding patients. Using incremental technologies, elements necessary for implant-prosthetic treatment, such as temporary prosthetic restorations designed to be attached to dental implants, are increasingly being made. They are mainly used in the osteointegration stage of the new implant with the bone, where they have both an aesthetic function, recreating the patient's smile from the first day after the procedure, and also a functional one, making it possible to return to normal life while waiting for the final permanent prosthesis [2,3]. Depending on the incremental technology used, different groups of materials are used, and so for FDM (Fused Deposition Modelling), these are thermoplastic materials, and for SLS (Selective Laser Sintering) photopolymer materials. In recent years, these are the ones that have gained popularity in dentistry [4,5]. Compared to other groups of materials, photopolymers stand out for their fast production time and high aesthetics of fabricated parts, making them an attractive choice for use in the production of temporary prosthetic restorations. Although these products are intended for use in the human body for no longer than 6 months, the durability of the materials under the changing conditions of the oral cavity, where they are exposed to dynamic chewing forces and temperature, is still a topic of research [4,6]. During activities of daily life such as speaking or chewing, a person makes an average of about 1500 to 2000 jaw movements per day, so the photopolymer materials used in dentistry must show sufficient resistance to cyclic loads [7,8]. The forces that occur during the occlusion phenomenon accompanying the contact between the upper and lower teeth can lead to the phenomenon of material fatigue, which can lead to wear or damage. In the context of temporary restorations that are to be used for only a few months, this aspect is extremely important. Any inconsistencies that arise in the healing stage of the oral cavity can affect the patient's comfort and health. Unfortunately, the available research on materials used in 3D printing in dentistry is mainly based on evaluating mechanical strength under static conditions [9]. The subject of fatigue testing remains largely under-researched. Comprehensive fatigue strength analyses of materials used for temporary reconstructions on implants are lacking in the literature [10]. Available studies focus on evaluating materials such as polyamides, polycarbonates, and epoxy resins, which are not used in medicine due to the lack of confirmation of their neutrality in the human body environment. They show that these materials have a high resistance to static loading, but their behaviour under cyclic loading is less stable, limiting their use in demanding oral conditions [11,12,13]. In consideration of the above, there is a need for full fatigue analyses of materials used in implant prosthetics for additive technologies. These will allow us to assess how these materials behave under prolonged, repetitive mechanical loads, sometimes even exceeding the patient's recommended range of use. Periodonal testing, otherwise known as fatigue analysis, is a key element in assessing the durability of dental materials, which usually show high resistance to static loads.