Reduction in maximal mouth-opening capacity and pain in the TMJ area proved to be reliable indices of TMDs. The effectivness of treatment of TMDs was judged from the interincisal opening distance.5 The interincisal distance was measured at the maximal mouth opening in the absence and presence of pain before and after each treatment. Additionally, subjective TMJ pain scores (on a scale of 0-10 points) were analyzed on a visual analogue scale (VAS) to evaluate pain in maximal mouth opening before and after each irradiation treatment.
The data were represented as means ± SDs. Two-factor ANOVA with repeated measures on one factor followed by Bonferroni correction of the paired t test was performed to determine if there was a significant difference in maximal mouth-opening distances and TMJ pain scores between the first visit and subsequent visits. The paired t test was performed before and after treatment during each visit. Probability values less than 0.05 were considered to be significant.
The painless maximal-mouth opening distance before treatment at the first visit was 33.4 ± 6.5 mm, and the painful maximal mouth-opening capacity was 37.6 ± 6.0 mm (see Fig. 6). These observed interincisal distances were shorter than those of healthy women.6-8 These distances were increased significantly by degrees before treatment. The average painless and painful maximal mouth-opening distances after the fifth treatment were 42.4 ± 5.7 mm (range, 33-53 mm) and 44.2 ± 4.2 mm (range, 39-53 mm), respectively. Compared with the first measured distance, the mouth-opening distances without pain increased by 7.6 ± 4.6 mm, and those with pain increased by 5.6 ± 4.3 mm as a result of our pilot treatment. These improvements in maximal mouth-opening distances were considered to be significant and clinically important.
Additionally, both painless and painful maximal mouth-opening distances measured immediately after each treatment were significantly longer than those measured before treatment. Although these improvements were not sustained until the next visit, the painless and painful mouth-opening distances measured at the fifth visit were maintained at the same lengths as the previous mouth-opening lengths measured after the fourth treatment.
All patients reported moderate pain (5.0 ± 2.7 points) associated with jaw movement in the unilateral mandibular condyle area when assessed using the VAS method at the first visit. Average pain scores for all patients at painful maximal mouth opening immediately after each treatment decreased relative to scores taken before treatment (Fig. 7).
Although this improvement was not sustained for a long period of time, pain scores before treatment decreased by degrees, with the fifth and final measured VAS values being 1.4 ± 1.6. The TMJ pain scores decreased significantly from the third visit onward. In addition, the pain scores measured at the fourth visit were maintained at the same pain scores as measured at the previous visit, which showed improvement during the previous treatment. From that stage onward, sustained relief has continued for 1 year without any treatment, and the VAS value at the 12-month follow-up examination was 0.5 ± 0.5. Our treatment had an analgesic effect on TMJ pain in the short term.
As regards the safety of this treatment, no complications occurred during the observed period.
The current pilot treatment involved the first known application of linearly polarized near-infrared irradiation to TMD patients. An advantage of the present method is that the probe used focuses the light beam to a diameter of 10 mm, enabling it to irradiate a broader region of the joint than the probes of conventional low-power lasers, which focus on a diameter of approximately 1 mm. Therefore, the Super Lizer does not require accuracy in selecting an irradiation point. Additionally, no complications were observed in any of the patients irradiated. Because the Super Lizer emits a high-energy light beam, there is a greater risk of creating a tingling sensation or of burning the skin when irradiating continuously for more than 3 seconds at the maximum power output of 1,800 mW than there is with low-power lasers. Therefore, we performed intermittent irradiation as shown in Figure 5.
The average painless maximal mouth-opening distance before treatment was 33.4 ± 6.5 mm, which represents a shorter interincisal distance than that of healthy women.6-8 Cox and Walker8 reported that the mean value of maximal mouth opening of 700 healthy Nepalese adults with an age range of 18 to 68 years was 47.1 mm (range: 33.7-60.4 mm) and that 98% of the population surveyed fell within this range. In the present pilot study, the average painful maximal mouth-opening distance at the fifth visit was 43.2 ± 4.5 mm (range: 36-53 mm), and it was suggested that our pilot treatment using the Super Lizer resulted in a marked maximal mouth opening. In the previous pilot study, the same treatment in RA-affected TMD patients alleviated TMJ pain, with the fifth visit arrival values of VAS being 0.3 ± 0.5, but showed no remarkable improvements in painful maximal mouth-opening capacity.2,3 The difference in results between RA-affected and non-RA-affected TMDs may be caused by degenerative changes in the mandibular condyle. Conti9 demonstrated that irradiation using a gallium aluminum arsenide 830-nm laser applied to TMD patients did not lead to any marked improvements in TMJ pain. Thus, some differences are evident in the mechanism of TMJ pain relief between the Super Lizer and other low-power lasers.10,11
Although painless and painful maximal mouth-opening distances increased markedly immediately after each treatment, these effects were not sustained until the next visit (Fig. 6 and 7). The maximum power output of the Super Lizer is 1,800 mW at a wavelength of 830 nm and is approximately 20 times as high as that of gallium aluminum arsenide 830-nm diode lasers. This high-energy light beam is partially converted to thermal energy and thus produces a warm sensation. The thermal actions of the Super Lizer probably contribute to these temporary immediate improvements.
Our treatment using the Super Lizer alleviated TMJ pain successfully. In terms of the thermal action on analgesic relief of pain, Carpenter12 showed that thermal energy had an influence on neuronal membrane potential. Additionally, Bellometti and Galzigna13 showed that thermal mud pack therapy using simple methods involving the application of heat decreased prostaglandin (PGE2) and leukotriene (LTB4) serum levels in osteoarthrosis. These researchers concluded that this therapy induced pain relief by reducing inflammatory reaction. Hence, the heat action of the Super Lizer can be a potential etiologic mechanism for relief from TMJ pain in short-term treatment. The potential exists for experimental bias and a placebo effect, however, given that all patients were aware that they were receiving a new treatment for TMDs. Further studies involving a random double-blind trial are needed to clarify the precise mechanism of TMJ pain relief using the Super Lizer.
Our pilot irradiation to four painful TMJ points using the Super Lizer provided relief from the TMJ pain in TMD patients over a period of 4 weeks without complications. Additionally, there was a marked improvement in maximal mouth opening length. The present findings suggest that both the light and thermal actions of the Super Lizer may contribute to relief from the TMJ pain in short-term treatment.
1. Eversole LR, Machado L. Temporomandibular joint internal derangements and associated neuromuscular disorders. J Am Dent Assoc
2. Yokoyama K, Oku T. Relief from the pain
of the juvenile rheumatoid arthritis-affected temporomandibular joint by the irradiation of linear polarized near infrared ray. Pain Clin
3. Yokoyama K, Oku T. Rheumatoid arthritis-affected temporomandibular joint pain analgesia
by linear polarized near infrared irradiation. Can J Anaesth
4. Vickers ER, Cousins MJ, Woodhouse A. Pain
description and severity of chronic orofacial pain
conditions. Aust Dent J
5. Yoshimura Y, Yoshida Y, Oka M, et al. Long-term evaluation of non-surgical treatment of osteoarthrosis of the temporomandibular joint. Int J Oral Surg
6. Landtwing K. Evaluation of the normal range of vertical mandibular opening in children and adolescents with special reference to age and stature. J Maxillofac Surg
7. Mezitis M, Rallis G, Zachariades N. The normal range of mouth opening
. J Oral Maxillofac Surg
8. Cox SC, Walker DM. Establishing a normal range for mouth opening
: its use in screening for oral submucous fibrosis. Br J Oral Maxillofac Surg
9. Conti PCR. Low level laser therapy in the treatment of temporomandibular disorders (TMD): a double-blind pilot study. J Craniomandib Pract
10. Snyder-Mackler L, Bork CE. Effect of helium-neon laser irradiation on peripheral sensory nerve latency. Phys Ther
11. Shimoyama N, Iijima K, Shimoyama M, et al. The effects of helium-neon laser on formalin-induced activity of dorsal horn neurons in the rat. J Clin Laser Med Surg
12. Carpenter DO. Temperature effects on pacemaker generation, membrane potential, and critical firing threshold in Aplysia neurons. J Gen Physiol
13. Bellometti S, Galzigna L. Serum levels of a prostaglandin and a leukotriene after thermal mud pack therapy. J Invest Med
Keywords:Copyright © 2001 Wolters Kluwer Health, Inc. All rights reserved.
Analgesia; Mouth opening; Near-infrared ray; Pain; Temporomandibular disorder