Background: Personality traits are one of the major factors influencing the behavior and functioning of an individual, and they play a crucial role in the development of psychosomatic disorders and diseases. This paper aimed to evaluate the importance of personality traits in temporomandibular disorder (TMDs) development using the NEO-FFI Personality Inventory by Paul Costa and Robert McCrae (the Five-Factor Model of Personality, known as the Big Five). Moreover, the relationship between personality type and the intensity of dysfunctional changes in the stomatognathic system was assessed using the NEO-FFI Personality Inventory by Paul Costa and Robert McCrae (the Five-Factor Model of Personality, known as the Big Five). Material and Methods: The study included a group of 75 adult participants (aged 19–52) with TMD diagnosed according to DC/TMD criteria and a control group of 75 participants without symptoms of dysfunction. The study consisted of a questionnaire and clinical study; the questionnaire included the NEO-FFI psychological questionnaire and a self-authored one. The clinical part consisted of extra- and intraoral dental examinations. Results: Participants who clenched their teeth showed a greater degree of conscientiousness than those who did not exhibit this symptom (p = 0.048). Presence of headaches was correlated with greater severity of neuroticism (p = 0.001). Moreover, participants with enamel cracks showed a lower intensity of extraversion (p = 0.039), and those with worn hard dental tissues showed a higher intensity of neuroticism (p = 0.03), a lower intensity of conscientiousness (p = 0.01), and a lower intensity of extroversion (p = 0.046). Acoustic symptoms during mandibular movements were found to be linked with a higher level of neuroticism (p = 0.020), a lower level of extraversion (p = 0.035), and a lower level of conscientiousness, whereas pain upon mandibular movements were linked to a lower level of conscientiousness (p = 0.025). Participants with pain upon palpation of the masticatory muscles showed a lower level of conscientiousness (p = 0.01) compared to those without pain symptoms. Episodes of mandibular blockage or problems with its adduction depend on the intensity of conscientiousness (p = 0.007). Moreover, people from the study group with high levels of neuroticism showed lower protrusion values (p = 0.016). Conclusion: The intensity of individual personality traits was found to be associated with some TMDs in comparison to healthy controls.