The Department of Stomatology of the National Institute of Respiratory Diseases requires diagnosing the level of bruxism suffered by Institute personnel. Bruxism is excessive teeth grinding or jaw clenching often related to stress or anxiety. It is an oral parafunctional activity that does not have a masticatory function that can lead to occlusal trauma. Bruxism can be diagnosed through the measurement of the Maximum Functional Masticatory Force (MFMF). This is an indicator of the functional state of the stomatognathic system (mouth, teeth, jaws, pharynx, and structures involved in chewing, swallowing, and speech) and it can be an indicator of the individual’s stress level. This force can be measured with a medical device called Gnathodynamometer. However, due to the commercial cost, it can be difficult to acquire. Therefore, the objective of this work was to design and build a prototype of a gnathodynamometer that can measure the MFMF up to 75 kgf, in two of the molar and premolar dental groups simultaneously, which could provide an auxiliary criterion for decision-making about diagnosis and treatment of patients who suffer bruxism. A prototype of a Gnathodynamometer was constructed. A preliminary functional test a strength test with a healthy subject, was made, as well as a strength test.