The Relationship Between Centric Relation-Maximum Intercuspation Disharmony and Temporomandibular Dysfunction in Class Ⅱ Patients

Objective To investigate the relationship between the degree of displacement of centric relation--maximum intercuspation (CR-MI) and temporomandibular dysfunction (TMD) in Class Ⅱ patients. Methods The questionnaire and clinical examination were administered in 107 Class Ⅱ patients and students, using the Helkimo index (Di and Ai). The differences in condylar position between CR and MI in all three spatial planes were measured using the Condyle Position Indication (CPI). Results Di positively correlated with degree of CR-MI displacement in all five displacement (P<0.05), while Ai positively correlated with degree of CR-MI displacement except horizontal displacement. Di and Ai significantly correlated with degree of CR-MI discrepancy in all five displacement (P<0.05); With the increasing of Di and Ai rank, the degree of CR-MI displacement and CR-MI discrepancy increased. Also, symptoms of TMD were significantly correlated with the degree of CR-MI displacement and CR-MI discrepancy except horizontal displacement (P<0.05). Severer CR-MI displacement and CR-MI discrepancy were observed in patients who had TMD symptoms. Conclusion In Class Ⅱ patients, degree of CR-MI displacement is an important factor of TMD, and correlated with the severity of TMD.