BACKGROUND Modern prosthetic technologies make it possible to fabricate prosthetic restorations without material loss and to make prosthetic restorations with complex geometric shapes in a relatively simple way. One such technology is selective laser melting (SLM), or additive manufacturing of metal materials, better known as 3D printing from metal or selective laser melting, but currently the most commonly used method is casting. The present study investigated use of dental chromium-cobalt alloys for prosthetic bridges and compared methods of processing dental chromium-cobalt alloys to obtain the best mechanical properties. MATERIAL AND METHODS We used dental chromium-cobalt alloy (SCHEFTNER GMBH) for laser melting StarbondCoSEeasy Powder with grain size of 10-30 µm and StarbondCoS alloy casting, made in accordance with the European standard EN ISO 22674. SLM-made specimens and induction melted alloy castings were prepared for the study. A centrifugal casting system with induction current melting of the metal alloy was used to produce the samples. The melting and casting process is automatic and limits changes in chemical composition. RESULTS The results show that none of the samples changed their chemical composition, while the samples made by SLM had better mechanical properties. CONCLUSIONS The SLM technique makes it possible to produce restorations faster and cheaper without any loss of quality compared to restorations made with the casting technique. Casting technology reduces mechanical properties, but still provides good mechanical properties.

Background/Objectives: Chronic stress has an undeniable effect in generating emotional disorders and physiological changes. It results in excessive muscle tension throughout the body, also in the masticatory system. A situation of chronic stress was the COVID-19 pandemic. The aim of this paper was to assess the prevalence of specific masticatory pain symptoms, their severity, and the co-occurrence of associated symptoms (otological symptoms and headaches) in patients diagnosed before and during the COVID-19 pandemic. Methods: A total of 202 patients were divided into two groups: Group A (mean age of 36.46; F = 64; and M = 37) and B (mean age of 26.04; F = 70; and M = 31) included patients who presented for the study before and after the COVID-19 pandemic, respectively. The Oral Behaviours Checklist (OBC) questionnaire was used: patients with result ≥2 scores in the OBC were evaluated by DC/TMD. To evaluate the intensity of pain in masticatory structures, the elements of the RDC-TMD questionnaire were used. Otologic symptoms and headaches were assessed as coexisted complaints. Results: A significant increase in pain occurrence was observed in Group B mainly for masseter muscles (p < 0.0001), temporalis (p = 0.0044), and medial pterygoid muscles (p = 0.0153). A significantly more frequent reporting of pain/tenderness was observed among men in most of the evaluated muscles. For the lateral pterygoid muscles, changes in palpation pain did not reach statistical significance. There was a statistically significant difference in the intensity of pain in the temporomandibular joint area between both the entire groups A and B (p = 0.000152), as well as between women in Group A and B (p = 0.006453) and men in the study groups (p = 0.007990). An increase in the incidence of headaches was observed among men in Group B (Group A with 40.6% vs. Group B with 67.3%). The most commonly reported otological symptom in both groups was ear pain and/or discomfort in the preauricular region, with the frequency of otological symptoms being higher in Group B. Conclusions: (1) The COVID-19 pandemic affected the incidence and severity of masticatory muscle pain and associated complaints. (2) A decrease in the age of patients reporting complaints of masticatory mm pain was observed during the COVID-19 pandemic. (3) An increase in the frequency of headaches was observed in the male group during the pan-demic, while in women there was an increase in palpation tenderness of masticatory muscles.