Table.
Activity [Location] | Purpose | Application |
---|---|---|
Initial visit [UB] | Collected:
● Informed consent ● Dental impressions ● DC/TMD examination results, completed forms ● Head CT |
Permitted:
● Protection of subjects’ rights ● Fabrication of oral appliances used in dynamic stereometry ● Group categorization (±DD) using DC/TMD, inclusion/exclusion criteria ● 3-dimensional craniomandibular anatomy for numerical modeling |
Imaging visit 1 [PIC] | Collected bilateral MR images of TMJs (1.5 T machine) | Permitted group categorization (±DD) using DC/TMD |
Imaging visit 2 [PIC] | Collected bilateral MR images of TMJs and reference system (using surface coils) | Characterized 3D TMJ anatomy for dynamic stereometry |
Laboratory visit 1 [UB] | Recorded
● Jaw tracking with reference system during static and dynamic jaw tasks ● Masseter and temporalis EMG bilaterally and bite forces during biting tasks Trained subject for ambulatory masseter and temporalis EMG |
Combined:
● Jaw tracking with MR images for dynamic stereometry to determine: ● Q, ΔD, x, y (to calculate ED) ● Eminence shapes (for numerical modeling) ● Subject- and muscle-specific EMG/bite-force data to determine T20 N for laboratory visit 1 Subjects self-recorded EMG unilaterally in their natural environments for 3 days, 3 nights |
Laboratory visit 2 [UB] | Collected ambulatory EMG equipment and data
Recorded masseter and temporalis EMG bilaterally and bite forces during biting tasks (repeated) |
Inspected and filtered completed ambulatory recordings
Determined T20 N for laboratory visit 2; averaged T20 N results for 2 visits and applied to ambulatory EMG for calculation of DF |
Data analysis [UB, UMKC, UZ] | Tested for ±DD group differences using:
● TMJ ED (from dynamic stereometry and numerical modeling) ● Jaw muscle DF (from ambulatory EMG recordings and T20 N) ● MBS (ED2 × DF) |
CT, computed tomography; ΔD, distance of stress-field translation, mm; ±DD, with/without disc displacement; DC/TMD, diagnostic criteria for temporomandibular disorders; ED, energy density; EMG, electromyography; MBS, mechanobehavioral scores; MR, magnetic resonance; PIC, private imaging center; Q, cartilage volume, mm3; T20N, average threshold of EMG activity for 20 N of bite force; TMJ, temporomandibular joint; UB, University at Buffalo School of Dental Medicine; UMKC, University of Missouri–Kansas City School of Dentistry; UZ, University of Zurich School of Dental Medicine; x, product of aspect ratio and compressive strain3; y, velocity of stress-field translation, mm/s.