BACKGROUND this study aims to validate two occlusal-force-measuring devices by comparing them to a universal testing machine and assessing their reliability across various dental and prosthetic groups. The research comprised two parts: part 1 assessed the measurement accuracy of the Occlusal Force Meter GM 10® (OFM) (Morita, Nagano Keiki, Higashimagome, Ohta-ku, Tokyo, Japan) and a prototype (PRO) by comparing them to a calibrated universal testing machine (ZWICK). Part 2 involved analyzing the devices' reliability based on clinical bite force measurements from study participants. RESULTS both devices become more accurate and reliable compared to the ZWICK over time of usage. Additionally, higher deviation from the ZWICK can be observed for higher values of forces applied and vice versa for both devices. The PRO's intraoral alignment influences its mean values compared to the OFM in different dental and prosthetic groups. CONCLUSIONS both devices had limitations and required quadratic function calibration, making them suitable only for progression measurements. The study concludes that both the OFM and PRO devices can measure occlusal forces with improved accuracy over time. Intraoral alignment should be considered. Their easy-to-use clinical application would allow a more widespread use of masticatory function diagnosis, which could indicate the need for treatment and improve treatment planning.