IADR Abstract Archives
The Effects of Posterior Bite Blocks on Brux-Like Motor Patterns.
Objectives: Posterior bite blocks can be used to increase the vertical occlusal dimension in dental patients with a deep overbite. Skeletal changes such as decreased lower face height are frequently associated with short and long-term use of posterior bite blocks. Electromyography (EMG) is a technique that allows for precise measurement of electrical activity produced by muscle fibers. The primary objective of the current study is to expand on previous results and characterize the impact of posterior bite block treatment on Brux-like patterns of the masseter muscle using EMGs.
Methods: Eight male Sprague-Dawley rats were housed under controlled 12/12 hour light/dark cycles. Two insulated, stainless steel fine-wire electrodes 0.14 mm in diameter with 0.5 mm exposed tips were inserted into the belly of the right masseter muscle, and sutured in place. An electrode pedestal was attached to a custom miniaturized preamplifier with a built in 100X gain. This preamplifier was connected to a 4-channel commutator mounted above the cage. The EMG signals were sent to a secondary Differential AC Amplifier for further amplification (x30) and set with low and high frequency cut-offs of 10 Hz and 10 kHz, respectively. We measured EMGs when the animal exhibited apparent brux-like behavior (no food). We used a non-parametric Kruskal-Wallis test for our statistical analysis.
Results: The EMG Burst duration indicates when the muscle was active, and the Cycle period as the time between the onset of a burst and a subsequent one. We compared a signfificant number of EMG bursts for each: Burst duration (n=225), and Cycle period (n=214). We found that the burst duration significantly increased after one week with Posterior bite blocks (p<.05).
Conclusions: The masticatory muscles are stretched or are under tension, and this produces proprioceptive feedback to the rythm generating circuity in the brainstem. Root mean square (RMS) measurement have been shown to represent the amplitude of the EMG signal. As such, we plan on increasing the number of animals used, and compare normalized mean RMS values for before and after posterior bite block treatment. Together this will inform us of both the timming and amplitude changes the masticatory system uses to compensate.
Methods: Eight male Sprague-Dawley rats were housed under controlled 12/12 hour light/dark cycles. Two insulated, stainless steel fine-wire electrodes 0.14 mm in diameter with 0.5 mm exposed tips were inserted into the belly of the right masseter muscle, and sutured in place. An electrode pedestal was attached to a custom miniaturized preamplifier with a built in 100X gain. This preamplifier was connected to a 4-channel commutator mounted above the cage. The EMG signals were sent to a secondary Differential AC Amplifier for further amplification (x30) and set with low and high frequency cut-offs of 10 Hz and 10 kHz, respectively. We measured EMGs when the animal exhibited apparent brux-like behavior (no food). We used a non-parametric Kruskal-Wallis test for our statistical analysis.
Results: The EMG Burst duration indicates when the muscle was active, and the Cycle period as the time between the onset of a burst and a subsequent one. We compared a signfificant number of EMG bursts for each: Burst duration (n=225), and Cycle period (n=214). We found that the burst duration significantly increased after one week with Posterior bite blocks (p<.05).
Conclusions: The masticatory muscles are stretched or are under tension, and this produces proprioceptive feedback to the rythm generating circuity in the brainstem. Root mean square (RMS) measurement have been shown to represent the amplitude of the EMG signal. As such, we plan on increasing the number of animals used, and compare normalized mean RMS values for before and after posterior bite block treatment. Together this will inform us of both the timming and amplitude changes the masticatory system uses to compensate.