IADR Abstract Archives
Mechanics and Behavior Associated With Longitudinal Changes in TMJ Integrity
Objectives: Given that fatigue of the TMJ articulating surfaces is related to magnitude and frequency of mechanical work done, the objective was to test if Mechanobehavior Scores (MBS) were correlated with longitudinal changes in TMJ integrity with respect to disc displacement or osseous mandibular condylar changes.
Methods: According to institutional review board oversight, diagnoses were determined in consenting subjects by calibrated examiners using Diagnostic Criteria for Temporomandibular Disorders protocols for two time-points (T1-T2). At T1, subjects were trained to record in-field jaw muscle electromyography, from which duty factors (DFs, % muscle activity time/recording time) were determined. Energy densities (ED, mJ/mm3) were estimated using modeled TMJ loads and in vivo dynamic stereometry. These data were combined to produce T1 MBS (ED2●DF, (mJ/mm3)2●%). T1-T2 changes in TMJ integrity over time were based on magnetic resonance and cone-beam computed tomography imaging criteria (Ahmad et al. 2009). Analysis of Variance and Tukey Honest Significant Difference post hoc tests were used to evaluate differences in MBS amongst subjects where TMJ integrity got worse, got better, or were unchanged, where significance was defined by p<0.05.
Results: Thirty-eight adult subjects (25 females, 13 males) consented to participate. T1-T2 were separated by an average of 6.8±2.1 years (range: 5.3-13.2 years). MBS were determined for 75 TMJs (38 right, 37 left). Forty-nine TMJs that were unchanged over time had average MBS (±Standard Error) of 216±45 (mJ/mm3)2●%. Thirteen TMJs (17%) that got worse over time had an average MBS of 528 ±209 (mJ/mm3)2●%. Both groups had significantly higher MBS (all p<0.01) compared to the 13 TMJs (17%, 80±24 (mJ/mm3)2●%) that got better over time.
Conclusions: Mechanobehavior score, a measure of magnitude and frequency of mechanical work imposed on the articulating surfaces of the TMJ, was significantly related to longitudinal changes in tissue integrity.
Methods: According to institutional review board oversight, diagnoses were determined in consenting subjects by calibrated examiners using Diagnostic Criteria for Temporomandibular Disorders protocols for two time-points (T1-T2). At T1, subjects were trained to record in-field jaw muscle electromyography, from which duty factors (DFs, % muscle activity time/recording time) were determined. Energy densities (ED, mJ/mm3) were estimated using modeled TMJ loads and in vivo dynamic stereometry. These data were combined to produce T1 MBS (ED2●DF, (mJ/mm3)2●%). T1-T2 changes in TMJ integrity over time were based on magnetic resonance and cone-beam computed tomography imaging criteria (Ahmad et al. 2009). Analysis of Variance and Tukey Honest Significant Difference post hoc tests were used to evaluate differences in MBS amongst subjects where TMJ integrity got worse, got better, or were unchanged, where significance was defined by p<0.05.
Results: Thirty-eight adult subjects (25 females, 13 males) consented to participate. T1-T2 were separated by an average of 6.8±2.1 years (range: 5.3-13.2 years). MBS were determined for 75 TMJs (38 right, 37 left). Forty-nine TMJs that were unchanged over time had average MBS (±Standard Error) of 216±45 (mJ/mm3)2●%. Thirteen TMJs (17%) that got worse over time had an average MBS of 528 ±209 (mJ/mm3)2●%. Both groups had significantly higher MBS (all p<0.01) compared to the 13 TMJs (17%, 80±24 (mJ/mm3)2●%) that got better over time.
Conclusions: Mechanobehavior score, a measure of magnitude and frequency of mechanical work imposed on the articulating surfaces of the TMJ, was significantly related to longitudinal changes in tissue integrity.