OBJECTIVE: To estimate the degree of self-assessed knowledge among dentists in Sweden and Saudi Arabia regarding temporomandibular disorders (TMD) in children and adolescents using a summative form of assessment and further to investigate the possible factors that may influence the self-assessed knowledge. MATERIALS AND METHODS: A questionnaire survey covering four domains (Etiology; Diagnosis and classification; Chronic pain and pain behavior; Treatment and prognosis) regarding TMD knowledge was used. Out of 250 questionnaires (125 in each country) a total of 65 (52%) were returned in Sweden and 104 (83%) in Saudi Arabia. RESULTS: Self-assessed individual knowledge was significantly associated to the level of actual knowledge among the Swedish groups in the domains Etiology; Diagnosis and classification and Treatment and prognosis (p < 0.05). However, in the Saudi Arabian groups a corresponding significant association was only found in the domain Diagnosis and classification (p < 0.05). CONCLUSIONS: This study showed that there is a difference in the accuracy of self-assessment of own knowledge between the dentists in Sweden and Saudi Arabia. The Swedish dentists have a better ability to assess their level of knowledge compared to Saudi Arabian dentists regarding TMD in children and adolescents. This difference could be related to several factors such as motivation, positive feedback, reflection, psychomotor, and interpersonal skills, which all are more dominant in the Swedish educational tradition.