Ah Ryum Chang1, Jeong Joon Han1, Dae-Seung Kim2, Won-Jin Yi3, Soon Jung Hwang4. 1. Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Research Institute, Seoul National University, Republic of Korea. 2. Interdisciplinary Program in Radiation, Applied Life Science Major, College of Medicine, BK21, and Dental Research Institute, Seoul National University, Republic of Korea. 3. Department of Oral and Maxillofacial Radiology, BK21, and Dental Research Institute, School of Dentistry, Seoul National University, Republic of Korea. Electronic address: wjyi@snu.ac.kr. 4. Department of Oral and Maxillofacial Surgery, School of Dentistry, Dental Research Institute, Seoul National University, Republic of Korea. Electronic address: sjhwang@snu.ac.kr.
Abstract
INTRODUCTION: Functional overloading can lead to disc displacement in the temporomandibular joint (TMJ), and a high incidence of disc displacement has been reported in patients with facial asymmetry. The aim of this study was to assess the dynamic condylar movement in patients (n = 26) with facial asymmetry using a simulation system with 3-dimensional computed tomographic images and tracking camera system. MATERIAL AND METHODS: The intra-articular distance (IAD) between the condyle and glenoid fossa was recorded during TMJ movement as a parameter for functional overloading and compared between Group I with severe asymmetry and Group II with mild asymmetry. RESULTS: The average IAD was shorter in Group I than Group II, especially at the lowest point (P < 0.05). The ratio of IAD narrowing in Group I was significantly larger than in Group II (P < 0.05). The mean IAD were slightly smaller on the deviated side (3.41 mm) than on the nondeviated side (3.55 mm) in Group I, even though there was no statistical significance. The maximum displacement in Group I was longer than in Group II and had no significant difference between deviated side and nondeviated side. CONCLUSION: We suggested that the reduced IAD resulting from TMJ overloading can lead to internal derangement in severe facial asymmetry.
INTRODUCTION: Functional overloading can lead to disc displacement in the temporomandibular joint (TMJ), and a high incidence of disc displacement has been reported in patients with facial asymmetry. The aim of this study was to assess the dynamic condylar movement in patients (n = 26) with facial asymmetry using a simulation system with 3-dimensional computed tomographic images and tracking camera system. MATERIAL AND METHODS: The intra-articular distance (IAD) between the condyle and glenoid fossa was recorded during TMJ movement as a parameter for functional overloading and compared between Group I with severe asymmetry and Group II with mild asymmetry. RESULTS: The average IAD was shorter in Group I than Group II, especially at the lowest point (P < 0.05). The ratio of IAD narrowing in Group I was significantly larger than in Group II (P < 0.05). The mean IAD were slightly smaller on the deviated side (3.41 mm) than on the nondeviated side (3.55 mm) in Group I, even though there was no statistical significance. The maximum displacement in Group I was longer than in Group II and had no significant difference between deviated side and nondeviated side. CONCLUSION: We suggested that the reduced IAD resulting from TMJ overloading can lead to internal derangement in severe facial asymmetry.