Groen, E.A. (2013) Jaw reflexes in patients with acute oro-facial pain. thesis, Dentistry.
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Abstract
One of the principal human jaw reflex, evoked by mechanical or noxious stimulation in or around the mouth, involves inhibition of activity within the jaw closing muscle such as the masseter and temporalis muscles. It has been suggested that this reflex, the inhibitory jaw reflex, has a protective function Several studies have shown that this reflex is depressed in patients with chronic oro-facial pain conditions, such as TMD (Temporomandibular Disorder), and by conditioning noxious stimuli applied to different parts of the body. It is not known however, whether TMD patients have altered jaw reflexes and are therefore susceptible to TMD, or whether pain from TMD alters the jaw reflexes. The objective of this experimental study was to investigate the influence of acute toothache, the most common form of oro-facial pain, on the inhibitory jaw reflex. By studying patients when they are in pain and when they are pain free, it can be investigated whether pain alters the inhibitory jaw reflex. The research question for this study is therefore: how is the inhibitory jaw reflex influenced in people with acute toothache in comparison with people without a toothache? The inhibitory jaw reflex is evoked by applying electrical stimuli to the perioral region of the upper lip. EMG (electromyogram) records are made from the masseter muscle on the site of the toothache while different intensities are applied in a random order using a computer program. During those records, the subject is biting on a rubber tube to provide a certain level of muscle activity. By studying the same patients on two occasions, they act as their own aged- and sex-matched control group. This makes it possible to detect if the reflex parameters, such as latency, duration, endpoint and magnitude or integral of the inhibitory wave, are altered and if some changes in the sensory and reflex threshold could be identified in patients in presence or absence of toothache. It was found in this study, that when the inhibitory effects were compared statistically, the endpoint of the reflex ended significantly earlier in all subjects when they had an acute toothache. In fact in one subject, the inhibitory jaw reflex was not even detected when toothache was present, but was present when the subject was pain-free. The sensory threshold and reflex thresholds did not differ significantly for when the subjects were in pain compared to when they were pain-free. Due to an artifact it was not possible to determine the latency and therefore also the duration and integral of the reflex. Even with the limitations of this study, it seems that the inhibitory reflex is weaker in patients with an acute toothache and that pain on its own causes a change in the inhibitory jaw reflex.The inhibitory jaw reflex is thought to be a protective reflex as it reduces the likelihood of overloading the temporomandibular joints, periodontal tissues and masticatory muscles. Thus it is possible that in patients with crania-mandibular pain disorders, such as TMD, the protective functions are less which on its own can also cause pain on the long term. These finding are in agreement with previous studies on chronic oro-facial pain, such as TMD, and when noxious stimuli were applied to remote parts of the body. This study is part of a long term research project at the University of Dundee. With a bigger research population and when all the reflex parameters are collected, more effective conclusions can be made. This study contributes to the evolving information on whether changes in the inhibitory jaw reflexes play a role in the diagnosis of painful conditions of the jaw muscles (e.g. TMD). Despite the number of experiments it can be tentatively concluded that the inhibitory jawreflex is weaker in patients with acute oro-facial pain and the data of this study can eventuallyaid in the diagnosis and maybe even treatment of crania-mandibular disorders in the future.
| Item Type: | Thesis (Thesis) |
|---|---|
| Supervisor name: | Juch, dr P.J.W. |
| Supervisor name: | Maillou, P. University of Dundee |
| Faculty: | Medical Sciences |
| Date Deposited: | 25 Jun 2020 10:39 |
| Last Modified: | 25 Jun 2020 10:39 |
| URI: | https://umcg.studenttheses.ub.rug.nl/id/eprint/107 |
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