Comparison of Temporomandibular Disorder Signs and Symptoms in CrossFit^® Athletes and Sedentary Individuals

(1) Background: A sedentary lifestyle may aggravate temporomandibular disorder (TMD) symptoms, increasing pain sensitivity and functional limitations. Physical exercise is recommended for pain management and improving quality of life. Comparing CrossFit^® athletes to sedentary individuals allows for examining whether regular high-intensity exercise impacts pain sensitivity and functional limitations associated with TMD. This cross-sectional study assessed the signs and symptoms of TMD in CrossFit^® athletes compared to sedentary individuals. (2) Methods: Participants (n = 121) were divided into four groups: sedentary with TMD (n = 39), sedentary without TMD (n = 37), CrossFit^® athletes with TMD (n = 23), and CrossFit^® athletes without TMD (n = 22). TMD signs and symptoms were evaluated using the Research Diagnostic Criteria for TMD (RDC/TMD) axis I, including mandibular movement patterns, range of motion, joint sounds, muscle pain, and jaw dysfunctions. Statistical analyses included chi-square and Dunn's post hoc tests, ANOVA, and Kruskal-Wallis tests. Correlation and regression analyses were performed to examine associations between CrossFit^® practice and TMD (p ≤ 0.05). (3) Results: Myofascial pain was the most common diagnosis. All athlete groups exhibited greater mandibular movement amplitudes (unassisted opening without pain, p < 0.001, and protrusion, p = 0.039) and less pain (p < 0.001) than sedentary individuals. Pain reports and palpation-induced pain in muscles and joints were significantly associated with a sedentary lifestyle and TMD (p < 0.001). Joint and muscle pain were more prevalent (frequent) among sedentary participants, regardless of TMD diagnosis. Linear regression analysis showed that sedentary individuals without TMD had significantly reduced unassisted mouth opening amplitudes compared to athletes without TMD (p < 0.05). (4) Conclusions: Pain in the masseter, temporalis, posterior digastric, and medial pterygoid muscles was the most common symptom in sedentary individuals with TMD. They experience higher frequency and intensity of pain, as well as greater limitations in mouth movement. Athletes showed higher frequency of joint noises.