PMID- 32789311 OWN - Quintessence Publishing Company, Ltd. CI - Copyright Quintessence Publishing Company, Ltd. OCI - Copyright Quintessence Publishing Company, Ltd. TA - Int J Comput Dent JT - International Journal of Computerized Dentistry IS - 2702-9514 (Electronic) IS - 1463-4201 (Print) IP - 3 VI - 23 PST - ppublish DP - 2020 PG - 235-244 LA - en TI - Biomechanical analysis of temporomandibular joint dynamics based on real-time magnetic resonance imaging FAU - Krohn, Sebastian AU - Krohn S FAU - Frahm, Jens AU - Frahm J FAU - Mahler, Alannah AU - Mahler A FAU - Dathe, Henning AU - Dathe H FAU - Sedaghat, Sam AU - Sedaghat S FAU - Kubein-Meesenburg, Dietmar AU - Kubein-Meesenburg D FAU - Linss, Florian AU - Linss F FAU - Wassmann, Torsten AU - Wassmann T FAU - Bürgers, Ralf AU - Bürgers R CN - OT - temporomandibular joint OT - jaw dynamics OT - biomechanics OT - real-time magnetic resonance imaging OT - instantaneous center of rotation AB - Aim: The traditional hinge axis theory of temporomandibular joint (TMJ) dynamics is increasingly being replaced by the theory of instantaneous centers of rotation (ICR). Typically, ICR determinations are based on theoretical calculations or three-dimensional approximations of finite element models. Materials and methods: With the advent of real-time magnetic resonance imaging (MRI), natural physiologic movements of the TMJ may be visualized with 15 frames per second. The present study employs real-time MRI to analyze the TMJ biomechanics of healthy volunteers during mandibular movements, with a special emphasis on horizontal condylar inclination (HCI) and ICR pathways. The Wilcoxon rank sum test was used to comparatively analyze ICR pathways of mandibular opening and closure. Results: Mean HCI was 34.8 degrees (± 11.3 degrees) and mean mandibular rotation was 26.6 degrees (± 7.2 degrees). Within a mandibular motion of 10 to 30 degrees, the resulting x- and y-translation during opening and closure of the mandible differed significantly (10 to 20 degrees, x: P = 0.02 and y: P < 0.01; 20 to 30 degrees, x: P < 0.001 and y: P = 0.01). Rotation of both 0 to 10 degrees and > 30 degrees showed no significant differences in x- and y-translation. Near occlusion movements differed only for y-translation (P < 0.01). Conclusion: Real-time MRI facilitates the direct recording of TMJ structures during physiologic mandibular movements. The present findings support the theory of ICR. Statistics confirmed that opening and closure of the mandible follow different ICR pathways, which might be due to muscular activity discrepancies during different movement directions. ICR pathways were similar within maximum interincisal distance (MID) and near occlusion (NO), which might be explained by limited extensibility of tissue fibers (MID) and tooth contact (NO), respectively. AID - 833741