Effects of exercise therapy on painful temporomandibular disorders.

Temporomandibular disorders (TMD) are common chronic musculoskeletal pain conditions among orofacial pain. Painful TMD condition such as myalgia and arthralgia can be managed by exercise therapy. However, as it is hard to access actual effect of each modality that is included in an exercise therapy programme due to multiple choice of the management modality, their efficacy remains controversial. Therefore, this review focused on the effects of exercise therapy for the management of painful TMD. The aims of this review were to summarise the effects of exercise therapy for major symptoms of painful TMD and to establish a guideline for the management of painful TMD, resulting in higher quality and reliability of dental treatment. In this review, exercise modalities are clearly defined as follows: mobilisation exercise, muscle strengthening exercise (resistance training), coordination exercise and postural exercise. Furthermore, pain intensity and range of movements were focused as outcome parameters in this review. Mobilisation exercise including manual therapy, passive jaw mobilisation with oral appliances and voluntary jaw exercise appeared to be a promising option for painful TMD conditions such as myalgia and arthralgia. This review addressed not only the effects of exercise therapy on various clinical conditions of painful TMD shown in the past, but also an urgent need for consensus among dentists and clinicians in terms of the management of each condition, as well as terminology.

Comparison of the Contact Force Exerted on Teeth by Conventional Macintosh Laryngoscope Versus Video Laryngoscopes.

During laryngoscopy, the laryngoscope blade sometimes comes in contact with the teeth, fracturing or dislocating them. However, no studies have compared the effects of newly marketed video laryngoscopes and the Macintosh laryngoscope (Mac) on teeth. In this study, we measured and compared the force exerted on the teeth of an intubating manikin by the Mac, the Airway Scope (Pentax), and the McGrath MAC (Covidien). The mean force exerted was 141.1 ± 15.7 kg by the Mac, 39.2 ± 10.3 kg by the Airway Scope, and 48.7 ± 6.7 kg by the McGrath MAC. No significant difference was observed between the Airway Scope and the McGrath MAC. When the Mac is inserted, the glottis has to be visually located from outside the oral cavity. However, a significant force is not necessary when inserting video laryngoscopes because a camera is mounted on the blade tip. In this laboratory model, the lower force exerted by the video laryngoscopes should contribute to a reduction in their impact on fracture or dislocation of teeth.

Depressing interleukin-1ß contributed to the synergistic effects of tramadol and minocycline on spinal nerve ligation-induced neuropathic pain.

Our previous study indicated that coadministration of tramadol and minocycline exerted synergistic effects on spinal nerve ligation (SNL)-induced neuropathic mechanical allodynia. However, the underlying mechanisms are still unclear. Recent reports indicated that spinal proinflammatory factor interleukin-1ß (IL-1ß) contributed to the development of neuropathic pain and the positive feedback communication between neuron and glia. Therefore, the present research is to confirm whether spinal IL-1ß-related pathway response contributes to the synergistic effects of tramadol and minocycline on SNL-induced neuropathic pain. Real-time RT-PCR demonstrated IL-1ß up-expression in the ipsilateral spinal dorsal horn 3 days after lesion, which could be significantly decreased by tramadol and minocycline coadministration. Immunofluorescence and Western blot indicated that SNL-induced microglial phosphorylated p38 (p-p38) upregulation was also inhibited by tramadol and minocycline coapplication. Meanwhile, intrathecal administration of p38 inhibitor SB203580 markedly alleviated mechanical allodynia whilst reducing IL-1ß and Fos expression induced by SNL. Moreover, intrathecal neutralized antibody of IL-1ß could depress SNL-induced mechanical allodynia and Fos expression. These results suggest that depressing SNL-induced aberrant activation of the spinal dorsal horn IL-1ß-related pathway contributes to the underlying mechanism of the synergistic effects of tramadol and minocycline coadministration on SNL-induced neuropathic mechanical allodynia.

Increased expression of interleukin-18 in the trigeminal spinal subnucleus caudalis after inferior alveolar nerve injury in the rat.

Interleukin-18 (IL-18) is an important regulator of innate and immune responses, and is known to be expressed in various types of cells and upregulated in pathological conditions including tissue injury and inflammation, suggesting it has both proinflammatory and compensatory roles. Here we show that IL-18 was increased in microglia in the trigeminal spinal subnucleus caudalis (Vc) after peripheral nerve injury. We used a trigeminal neuropathic pain model in which the withdrawal threshold of maxillary whisker pad skin was significantly decreased after inferior alveolar nerve transection, and observed a striking increase in IL-18 expression in the Vc around the obex area from 3d and continued until 14d after nerve injury. The IL-18 labeled cells were largely colocalized with Iba1, suggesting this upregulation occurred in hyperactive microglia. We also found that the IL-18 induction coexisted with phosphorylated p38 MAPK, indicating a possible role of p38 in the regulation of IL-18. Our findings are the first report that injury of trigeminal nerve induced IL-18 upregulation in activated microglia in the Vc, suggesting a possible role of IL-18 in orofacial neuropathic pain.

Influences of molar loss of rat on learning and memory.

PURPOSE: The maxillary unilateral or bilateral molars of rats were extracted, and the influences of the partial loss of occlusal support were evaluated using an 8-arm radial maze and a step-through type passive-avoidance apparatus. METHODS: Rats were randomly allocated to three groups not undergoing molar extraction or undergoing extraction of the maxillary unilateral or bilateral molars. Each group was further divided into two groups for maze or passive-avoidance experiments. Thus, a total of six groups were established. The maze experiment was conducted once daily for 10 days. The number of correct choices, number of errors, and the trial time were recorded. The passive-avoidance experiment consisted of an acquisition trial and retention trial. In the acquisition trial, rats were placed in a light room, and the response latency until their entry into a dark room was measured. After 24h, a similar procedure was performed as a retention trial. RESULTS: In the maze experiment, there was no significant difference by all the groups except on the day 1 in the number of correct choices. But bilateral molar loss group, the number of errors were significantly lower than no extraction group on days 1, 2, 3, 4, and 7. In the passive-avoidance experiment, though the response latency in the retention trial was longer than that in the acquisition trial in all three groups, according to the increase in the number of tooth extraction, it became significantly shorter between P1 and P3. CONCLUSION: These results suggested that molar loss may be a cause of learning/memory impairment.