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Pain relief effects of semiconductor laser irradiation
International Congress Series 1248 (2003) 459 – 463
Pain relief effects of semiconductor laser irradiation Eiichi Sakuraba *, Akiko Sekine, Takashi Yanagisawa, Akiyo Yamamoto, Ryosuke Hasegawa, Kazuyuki Kobayashi, Hiroyasu Yamaguchi, Kazuhiro Gomi, Takashi Arai Department of Periodontics and Endodontics, Tsurumi University School of Dental Medicine, Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan
Abstract The purpose of this study was to evaluate the pain relief effects of continuous wave and chopper pulsed wave by semiconductor laser irradiation. The irradiation conditions were as follows: Group A, continuous wave (laser energy 1 w, irradiation time 60 s); Group B, chopper pulsed wave of 20 ms (laser energy 2 w, irradiation time 60 s); Group C, chopper pulsed wave of 20 ms (laser energy 1 w, irradiation time 120 s); and Group D, dummy irradiation. The pain relief effects were evaluated on pulp thermal sensitivity and surface anaesthetic effect. (1) Evaluation of pulp thermal sensitivity: the degree of pulp thermal sensitivity was measured by a pain thermometer on irradiation sites and control sites. (2) Evaluation of surface anaesthetic effects: the mucobaccal holds were penetrated with a 30-gauge cartridge needle, and each subject reported an immediate response to needle penetration on irradiation sites and control sites. For these results of pain relief effects on pulp thermal sensitivity and surface anaesthetic effects, there was statistically significant difference in pain relief effects between the irradiation conditions of chopper pulsed wave and control ( P < 0.05: paired t-test). Also, the irradiation conditions of Group C were significantly more effective than those of Group A. And there was no significant difference between dummy irradiation and control. This study suggests that semiconductor laser irradiation may be useful for pain relief. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Pain relief effects; Semiconductor laser; Continuous wave; Chopper pulsed wave; Dummy irradiation
* Corresponding author. E-mail address: [email protected] (E. Sakuraba). 0531-5131/03 D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0531-5131(03)00052-9
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E. Sakuraba et al. / International Congress Series 1248 (2003) 459–463
1. Introduction The laser is widely used in medical and dental fields, which have a wide range of applications. In general surgery, ophthalmology and dermatology as well as in periodontal surgery, lasers are applied for treatment as the modern technological methods. Recently, the effect of pain relief using various lasers has been investigated. The purpose of this study was to evaluate pain relief effects of continuous wave and chopper pulsed wave of semiconductor laser irradiation.
2. Materials and methods The mandibular canines and mucogingival areas of 10 human subjects (4 males, 6 females; age range, 25 – 37 years) were examined in this study. The right side of the mandible was used as a test site and the left side was used as a control side which was not irradiated. The semiconductor laser LIGHT SURGE 3000 (OSADA, JAPAN) was used in this study. The irradiation conditions were as follows: Group A: Group B: 60 s). Group C: 120 s). Group D:
continuous wave (laser energy 1 w, irradiation time 60 s). chopper pulsed wave of 20 ms (laser energy 2 w, irradiation time chopper pulsed wave of 20 ms (laser energy 1 w, irradiation time dummy irradiation.
The pain relief effects were evaluated by measuring pulp thermal sensitivity and surface anaesthetic effect. 2.1. Evaluation of pulp thermal sensitivity The degree of pulp thermal sensitivity was measured by a pain thermometer on irradiation sites and control sites. Immediately after laser irradiation, the buccal surfaces of canines were heated by the tip of a heat probe from 30 to 65 jC. One week after laser irradiation, pulp thermal sensitivity was measured again. 2.2. Evaluation of surface anaesthetic effects The mucobaccal holds of canine areas were penetrated by a 30-gauge cartridge needle, and each subject reported the degree of needle penetration produced on irradiated sites and control sites. The degree of pain was classified into three grades: grade 1, no pain; grade 2, slight pain; grade 3, pain.
E. Sakuraba et al. / International Congress Series 1248 (2003) 459–463
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One week after laser irradiation, surface anaesthetic effects were examined again.
3. Results 3.1. Evaluation of pulp thermal sensitivity The continuous wave group (Group A) and chopper pulsed wave groups (Groups B and C) indicated significantly lower sensitivities for temperature than the control group (paired t-test; p < 0.05). However, there was no significant difference between the control group and the dummy group (Group D) (Fig. 1). When compared to each test group (Group A, Group B and Group C), there were no significant differences between them (Fig. 2). One week after laser irradiation, there were no significant differences between the sensitivity of the control and test groups as measured by the pain thermometer. 3.2. Evaluation of surface anaesthetic effects The evaluation of pain by needle penetration is shown in Fig. 3. The effects of surface anaesthesia of Group B and Group C were significantly higher than the control group and Group D (paired t-test; p < 0.05).
Fig. 1. Change of the pulp thermal sensitivity.
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Fig. 2. Change of the pulp thermal sensitivity by the difference in the irradiation method.
In Group C with a chopper pulsed wave of 20 ms, the pain was significantly inhibited ( p < 0.05) compared to Group A, which was the condition of continuous wave. After 1 week, this surface anaesthetic effect had returned to previously normal values.
Fig. 3. Evaluation of the pain at the time of the needle penetration.
E. Sakuraba et al. / International Congress Series 1248 (2003) 459–463
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4. Discussions and conclusions This study compared the effects of chopper pulsed wave lasers and continuous wave lasers with identical total output energy, and examined the clinical effectiveness for pain relief of these two waves. At the pulp thermal sensitivity, test groups (Groups A, B and C) demonstrated significantly increased threshold of pulp thermal sensitivity compared to controls. However, there were no significant differences between each test group. At the surface anaesthetic effects, there were no significant differences between chopper pulsed wave groups (Groups B and C). Although, Group C (chopper pulsed wave) indicated a significant reduction of pain than Group A (continuous wave group). This result shows that if total output energy was the same, the application of chopper wave can achieve more effective surface anaesthesia than continuous wave. This study suggests that semiconductor laser irradiation is useful for pain relief, and this pain relief is reversible. We can find some reports on the mechanism of the pain relief with semiconductor laser irradiation. These pain relief mechanisms are based on the following: the inhibition of the releases of the endogenous algogenic substances [1], the specific inhibition of the conduction of the action potentials in the peripheral sensory nerve fibers [2], the improvement of circulation in the peripheral blood vessel [3], and the hyperpolarization of the membrane potentials of the sympathetic ganglion cells [4]. In this study, we found reversible pain relief by semiconductor laser irradiation. Now, we are investigating the direct effects on the conduction of the action potentials in the tactile fine nerve bundle of the African clawed frog (Xenopus), with the same condition as this study.
References [1] A. Honmura, M. Yanase, J. Obata, et al., Therapeutic effect of Ga – Al – As dilde laser irradiation on experimentally induced inflammation in rat, Laser Surg. 12 (1992) 441 – 449. [2] S. Mezawa, M. Siomo, N. Hattori, et al., Effect of soft-laser irradiation on the responses elicited by electrical and heat stimulation of the cat tongue, Jpn. J. Conserv. Dent. 31 (2) (1988) 584 – 593. [3] Z.F. Garrgoulitos, A.J. Welch, K.R. Piller, et al., Laser-irradiation-induced relaxation of blood vessels in vivo, Laser Surg. Med. 10 (1990) 524 – 532. [4] M. Simoyama, Y. Fukuda, et al., Effect of He – Ne laser irradiation on synaptic transmission on the superior cervical ganglion in the rat, J. Clin. Laser Med. Surg. 10 (1992) 337 – 342.
Pain relief effects of semiconductor laser irradiation Eiichi Sakuraba *, Akiko Sekine, Takashi Yanagisawa, Akiyo Yamamoto, Ryosuke Hasegawa, Kazuyuki Kobayashi, Hiroyasu Yamaguchi, Kazuhiro Gomi, Takashi Arai Department of Periodontics and Endodontics, Tsurumi University School of Dental Medicine, Tsurumi, Tsurumi-ku, Yokohama 230-8501, Japan
Abstract The purpose of this study was to evaluate the pain relief effects of continuous wave and chopper pulsed wave by semiconductor laser irradiation. The irradiation conditions were as follows: Group A, continuous wave (laser energy 1 w, irradiation time 60 s); Group B, chopper pulsed wave of 20 ms (laser energy 2 w, irradiation time 60 s); Group C, chopper pulsed wave of 20 ms (laser energy 1 w, irradiation time 120 s); and Group D, dummy irradiation. The pain relief effects were evaluated on pulp thermal sensitivity and surface anaesthetic effect. (1) Evaluation of pulp thermal sensitivity: the degree of pulp thermal sensitivity was measured by a pain thermometer on irradiation sites and control sites. (2) Evaluation of surface anaesthetic effects: the mucobaccal holds were penetrated with a 30-gauge cartridge needle, and each subject reported an immediate response to needle penetration on irradiation sites and control sites. For these results of pain relief effects on pulp thermal sensitivity and surface anaesthetic effects, there was statistically significant difference in pain relief effects between the irradiation conditions of chopper pulsed wave and control ( P < 0.05: paired t-test). Also, the irradiation conditions of Group C were significantly more effective than those of Group A. And there was no significant difference between dummy irradiation and control. This study suggests that semiconductor laser irradiation may be useful for pain relief. D 2003 Elsevier Science B.V. All rights reserved. Keywords: Pain relief effects; Semiconductor laser; Continuous wave; Chopper pulsed wave; Dummy irradiation
* Corresponding author. E-mail address: [email protected] (E. Sakuraba). 0531-5131/03 D 2003 Elsevier Science B.V. All rights reserved. doi:10.1016/S0531-5131(03)00052-9
460
E. Sakuraba et al. / International Congress Series 1248 (2003) 459–463
1. Introduction The laser is widely used in medical and dental fields, which have a wide range of applications. In general surgery, ophthalmology and dermatology as well as in periodontal surgery, lasers are applied for treatment as the modern technological methods. Recently, the effect of pain relief using various lasers has been investigated. The purpose of this study was to evaluate pain relief effects of continuous wave and chopper pulsed wave of semiconductor laser irradiation.
2. Materials and methods The mandibular canines and mucogingival areas of 10 human subjects (4 males, 6 females; age range, 25 – 37 years) were examined in this study. The right side of the mandible was used as a test site and the left side was used as a control side which was not irradiated. The semiconductor laser LIGHT SURGE 3000 (OSADA, JAPAN) was used in this study. The irradiation conditions were as follows: Group A: Group B: 60 s). Group C: 120 s). Group D:
continuous wave (laser energy 1 w, irradiation time 60 s). chopper pulsed wave of 20 ms (laser energy 2 w, irradiation time chopper pulsed wave of 20 ms (laser energy 1 w, irradiation time dummy irradiation.
The pain relief effects were evaluated by measuring pulp thermal sensitivity and surface anaesthetic effect. 2.1. Evaluation of pulp thermal sensitivity The degree of pulp thermal sensitivity was measured by a pain thermometer on irradiation sites and control sites. Immediately after laser irradiation, the buccal surfaces of canines were heated by the tip of a heat probe from 30 to 65 jC. One week after laser irradiation, pulp thermal sensitivity was measured again. 2.2. Evaluation of surface anaesthetic effects The mucobaccal holds of canine areas were penetrated by a 30-gauge cartridge needle, and each subject reported the degree of needle penetration produced on irradiated sites and control sites. The degree of pain was classified into three grades: grade 1, no pain; grade 2, slight pain; grade 3, pain.
E. Sakuraba et al. / International Congress Series 1248 (2003) 459–463
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One week after laser irradiation, surface anaesthetic effects were examined again.
3. Results 3.1. Evaluation of pulp thermal sensitivity The continuous wave group (Group A) and chopper pulsed wave groups (Groups B and C) indicated significantly lower sensitivities for temperature than the control group (paired t-test; p < 0.05). However, there was no significant difference between the control group and the dummy group (Group D) (Fig. 1). When compared to each test group (Group A, Group B and Group C), there were no significant differences between them (Fig. 2). One week after laser irradiation, there were no significant differences between the sensitivity of the control and test groups as measured by the pain thermometer. 3.2. Evaluation of surface anaesthetic effects The evaluation of pain by needle penetration is shown in Fig. 3. The effects of surface anaesthesia of Group B and Group C were significantly higher than the control group and Group D (paired t-test; p < 0.05).
Fig. 1. Change of the pulp thermal sensitivity.
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Fig. 2. Change of the pulp thermal sensitivity by the difference in the irradiation method.
In Group C with a chopper pulsed wave of 20 ms, the pain was significantly inhibited ( p < 0.05) compared to Group A, which was the condition of continuous wave. After 1 week, this surface anaesthetic effect had returned to previously normal values.
Fig. 3. Evaluation of the pain at the time of the needle penetration.
E. Sakuraba et al. / International Congress Series 1248 (2003) 459–463
463
4. Discussions and conclusions This study compared the effects of chopper pulsed wave lasers and continuous wave lasers with identical total output energy, and examined the clinical effectiveness for pain relief of these two waves. At the pulp thermal sensitivity, test groups (Groups A, B and C) demonstrated significantly increased threshold of pulp thermal sensitivity compared to controls. However, there were no significant differences between each test group. At the surface anaesthetic effects, there were no significant differences between chopper pulsed wave groups (Groups B and C). Although, Group C (chopper pulsed wave) indicated a significant reduction of pain than Group A (continuous wave group). This result shows that if total output energy was the same, the application of chopper wave can achieve more effective surface anaesthesia than continuous wave. This study suggests that semiconductor laser irradiation is useful for pain relief, and this pain relief is reversible. We can find some reports on the mechanism of the pain relief with semiconductor laser irradiation. These pain relief mechanisms are based on the following: the inhibition of the releases of the endogenous algogenic substances [1], the specific inhibition of the conduction of the action potentials in the peripheral sensory nerve fibers [2], the improvement of circulation in the peripheral blood vessel [3], and the hyperpolarization of the membrane potentials of the sympathetic ganglion cells [4]. In this study, we found reversible pain relief by semiconductor laser irradiation. Now, we are investigating the direct effects on the conduction of the action potentials in the tactile fine nerve bundle of the African clawed frog (Xenopus), with the same condition as this study.
References [1] A. Honmura, M. Yanase, J. Obata, et al., Therapeutic effect of Ga – Al – As dilde laser irradiation on experimentally induced inflammation in rat, Laser Surg. 12 (1992) 441 – 449. [2] S. Mezawa, M. Siomo, N. Hattori, et al., Effect of soft-laser irradiation on the responses elicited by electrical and heat stimulation of the cat tongue, Jpn. J. Conserv. Dent. 31 (2) (1988) 584 – 593. [3] Z.F. Garrgoulitos, A.J. Welch, K.R. Piller, et al., Laser-irradiation-induced relaxation of blood vessels in vivo, Laser Surg. Med. 10 (1990) 524 – 532. [4] M. Simoyama, Y. Fukuda, et al., Effect of He – Ne laser irradiation on synaptic transmission on the superior cervical ganglion in the rat, J. Clin. Laser Med. Surg. 10 (1992) 337 – 342.