Histometrical Evaluation of the Healing of the Dental Alveolus in Rats After Irradiation with a Low-Powered GaAlAs Laser

Rosane F. Z. Lizarelli*; Tereza L. Lamano-Carvalho**; Luis G. Brentegani** *Physics Institute of São Carlos, University of São Paulo, São Carlos, SP, Brazil. 13560-970 **College of Dentistry of Ribeirao Preto, University of São Paulo, Ribeirao Preto, SP, Brazil. 14.040-000 LIZARELLI, R. F. Z.; LAMANO-CARVALHO, T. L.; BRENTEGANI, L. G.

Histometrical evaluation of the healing of the dental alveolus in rats after irradiation with a low-powered GaAlAs laser. in Lasers in Dentistry V, John D. B. Featherstone, Peter Rechmann, D.D.S., Daniel Fried, Editors, Proceedingsof SPIE Vol. 3593, p. 49-56, 1999. ABSTRACT The aim of the present work was to evaluate histometrically the effect of the irradiation with semiconductor diode GaAlAs 790 nm low-powered laser in the chronology of alveolar repair of rats.
Lasers of low intensity possesses an eminently analgesic, anti-inflammatory and bioestimulant effect, producing an increase of the local micro-circulation and in the speed of healing. Groups of five animals had their upper right incisors extracted under anesthesia and the mucous sutured; three groups received 1.5 J/cm2 of irradiation immediately after the extraction with laser for sweeping on the operated area. After that, the animals were sacrificed in the periods of 7, 14 and 21 days after the dental extraction. The material was decalcified and processed for inclusion in paraffin. Longitudinal sections of 7 micrometers in the alveolus were made and stained with HE.
The histometric analysis was performed with the Merz grid, and 2000 points were counted in each cervical, middle and apical thirds of the alveolus, assessing the percentage of the bone tissue. The results shows that low-powered intensity laser produced acceleration in osseous formation (10%) in some periods. The influence of low-powered laser on the healing process is more significant when we can apply the laser light just after the tissue trauma. Cells with a lower than normal pH, where the redox state is shifted in the reduced direction, are considered to be more sensitive to the stimulate action of light than those with the respective parameters being optimal or near optimal. The proposed redox-regulation mechanism may be a fundamental explanation for some clinical effects of irradiation, a consequence of this was the difference between the groups of 7 days is more significant than between the other groups.

Wound healing Waynant R, US Food & Drug Administration: results from a preliminary wound healing trial.
Notes from a presentation at The 2nd Congress of The world Assoc. for Laser Therapy, Kansas, MO, USA, Sept. 2.5 1998.

A pilot study used six Sprague-Dawley rats - three controls with no treatment and three that were irradiated for 250 seconds with 630 nm. All rats were wounded on both hips - an 8mm circular full thickness hole. The irradiated rats received the 630nm 5 J/cm2 dose on only the left hip. The animals were irradiated one hour after the wounds were given and then one dose per day for four days. The results are: ten days after wounding the closure on the control rats averaged 26%, but irradiated rats averaged a closure of 65% on both left (irradiated) and right hips - a systemic effect on the right, as it received no irradiation.

Lymphadenitis
Oasevich I A, Shargorodskii A G. (Low-intensity infrared laser radiation in the diagnosis and combined treatment of acute nonspecific lymphadenitis of the face and neck in children) Infrakrasnoe nizkointensivnoe lazernoe izluchenie v diagnostike i kompleksnom lechenii ostrogo nespetsificheskogo limfadenita litsa i shei u detei. Stomatologiia (Mosk). 1999; 78 (2): 28-30,

The clinical course of acute nonspecific lymphadenitis of the face and neck was studied in 241 patients aged 1-14 years, in order to improve the diagnosis and therapy of this condition. General clinical examinations were supplemented by laser biophotometry and assessment of the activities of some local defense factors (lysozyme, beta-lysine, secretory and serum IgA). Multiple-modality treatment for the first time included magnetic laser therapy (MLT), and its efficacy was assessed. Results of biophotometry helped define the objective criteria for the diagnosis and evaluation of the treatment efficacy in children with acute lymphadenitis of the face and neck. MLT proved to be a highly effective treatment modality, decreasing the inflammation and correcting oral factors. Use of MLT accelerated all phases of the inflammatory process, promoted its regression at the serous stage, and decreased the incidence of suppurative forms of acute lymphadenitis by 40%.

Nerve effects
a) Ohno T. Pain suppressive effect of low power laser irradiation. A quantitative analysis of substance P in the rat spinal dorsal root ganglion. J Nippon Med Sch. 1997; 64 (5): 395-400. (In Japanese with English abstract)

Under anesthesia, the right sciatic nerve of 41 rats was exposed. 13 rats received laser irradiation and electrical stimulation, 16 rats only electrical stimulation and 12 served as control. Immediately after the electrical stimulation, with or withour laser irradiation, DRG of the 4th to 6th lumbar spinal roots were excised. Immunohistochemical substance P staining and substance P-like immunoreactivity (SP-LI) quantification were done in the excised DRG. There was a statistically significant difference of SP-LI between the control group and the stimulated group. There was no statistically significant difference between the laser irradiation only group and control. These results suggest that laser irradiation suppresses the exitation of the unmyelinated C-fibers in the afferent sensory pathway.

b) Tsuchiya K et al. Diode laser irradiation selectively diminishes slow component of axonal volleys to dorsal roots from the saphenous nerve. Neuroscience Letters. 1993; 161: 65-68.

GaAlAs laser irradiation inhibited the action potentials in the dorsal roots eleicited from the spahenous nerve of the rat. After 830 nm irradiation to the nerve, the amplitude of slower conduction parts of action potentials( <12 m/s) were suppressed. The suppression was dose dependent. After 3 minutes of irradiation the slowest conduction velocity group (<1.3 m/s) were totally diminished and the 1.3-12 m/s group were reduced to 12-67%. In contrast, faster component(>12 m/s) was unaffected by the irradiation. It is suggested that laser irradiation may selectively target fibers conducting at slow velocities which include afferent axons from nociceptors.

Dental
Kurumada F. A study of the application of Ga-As semiconductor laser to endodontics. The effect of laser irradiation on the activation of inflammatory cells and the vital pulpotomy. J Clinical Pediatric Dentistry. 1995; 19: 232.

The effects of GaAs on the activation of machrophages and fibroblasts were examined be determinating the rate of glucose utilization into the cell and the activity of lactate dehydrogenase in culture supernatant. The irradiated macrophages that had been prepared from the perioneal exudate cells, did not show any enhancement of activity, whereas the fibroblast cell line was activated by laser irradiation.
These findings suggest that GaAs irradiation was effective for the growth of fibroblasts and induced suppressive effects for macrophages. Further, the effects of laser on the vital pulpotomy were investigated. It was observed that irradiation induced enhancement of calcification in the wound surface and stimulated formation of calcified tissue. These observations indicate that laser irradiation is a useful method for the vital pulpotomy.

Laser acupuncture special: recent reports:

Laser acupuncture reduces postoperative vomiting.
In a double blind, randomized, placebo controlled study the effectiveness of point P6 acupuncture on postoperative vomiting in children undergoing strabismus (eye) surgery, was studied. A 10 mW 670 nm laser was used and the P6 point was irradiated for 30 seconds 15 minutes before anesthesia and 15 minutes after arriving in the recovery room. In the laser group the incidence of vomiting was 25%. in thge placebo group 85%.

Schlager A et al. Laser stimulation of acupuncture point P6 reduces postoperative vomiting in children undergoing strabismus surgery. Br J Anesth. 1998; 81 (4): 529-532.

Abstracts of ICMART '97 International Medical Acupuncture Symposium, Nicosia, Cyprus, March 26-29 1997:
1) Low energy laser in the treatment of low back pain S. Nikolic, Z. Trojacanec, I.J. Milankovic Institute of ME Physiology, Faculty of Medicine, Skopje, F.Y.R.O.M

Low back pain is felt in the low lumbar, lumbosacral, or sacroiliac region. Most low back pain is related to acute ligamentous (sprain) or muscular(strain) problems, which tend to be self limited, or to the more chronic osteoarthritis or ankylosing spondylitis of the lumbar area. The aim of the study was to explore the pain-alleviating effect of low level laser in low back pain .Thirty-five patients with low back pain have been treated with helium-neon laser type "Bistra" with wavelength 630 nm, average output 15 mW and an irradiance of 250 mW/cm2. The laser was locally applied to 11 sites on and around the low back. After scanning each point was treated for 30 sec, five times weekly for a total of ten treatments. The statistical analysis showed that the laser treated patients had a significant faster pain-alleviating effect compared with the 30 patients treated with medicaments only. Subjective response have been achieved after first three treatments. Irradia laser treatment may be a valuable therapy in low back pain and low energy laser can be employed as a pain relieving method.

2) Laserpuncture in patients with rheumatoids arthritis.
Poliakova A.G., Gladkova N.D., Triphonova T.D. Russia 603155 N. Novgorod., V. Volznskava Nab., 18., Research Institute of Traumatology & Orthopedics

The purpose of this investigation: to determine of laserpuncture (LP) clinical effectiveness among other LT methods in RA concerning pain and articular inflammation.
Results of treatment in 330 patients with diagnosed RA in acute phase in resistance of bases therapy (Voltaren, Indometacin in 100-150 mg during 24h.) were studied.
(1) The investigations were carried out with double-blind controlled placebo tests.
(2) Intravascular radiation (IR) with wavelength 633 nm, articularsurface radiation (ASR) with wavelength 820 nm in continuos regime and
(3) with 890 nm (LP) in pulsed modulated regime with frequency 1-100 Hz methods were compared.

Assessment results of treatment in all groups was performed in accordance with integral clinical value and blood indexes dynamics. Results indicated positive effects (65%) in patients treated with ASR and LP, and were similar. However, ASR method requires 100 points/session versus 10 points/session in LP. Methods of ASR and LP in doses 0,004-0,02 Dj/cm2 (density of energy flow) provided maximal analgesic effect without any side effects and complications. Usage of IR was less effective (12%) and in two cases status impairment or pain and articular syndrome activization were seen.

Conclusion: LP is an optimal supplementary method (in above mentioned parameters) in RA treatment, In our opinion, IR method of LT has some disadvantages and less efficiency. Thus, this method should not be recommended in RA treatment.

3) Application of laser acupuncture in the treatment of periarthritis humeroscapularis.
Branka Nikolic,. spec. Sport's med. Address Zavod za zdravstvenu zastitu radnika ZTP-a "Beograd", 11000 Beograd, Slobodana Penezica Dr. 23 Yugoslavia

The effect of low intensity semi conductor laser was used as treatment methods for periarthritis humeroscapularis. The CC laser (Computer Controlled laser) was applied.
Laser therapy has positive biological effects and antiinflamatory, antioedema effects and analgesia. We treated 18 patients with periarthritis humeroscapularis, 14 were female patients.
The laser was locally applied at the AC points Sj 14, Sj 15, Li 15, Li 10, Sj 5, Si 3, three times a week for the first week and twice a week for the second and the third week. After first treatment 12 of patients had pain - alleviating effect. After 6-7 treatments al had pain - alleviating effect and complete recovery of shoulder's motor activity. Low intensity therapy has its place for treatment of periarthritis humeroscapularis.

4) Laser therapy and immunostimulators in patients with acute orofacial infections.
Kjusepashova Ts., Haydouchka I., Indjov St., Gospodinov D., Wurdjeva M Address Dept. Physical Med. & Rehabil., Plovdiv Med. Institute, 15A V. Aprilov. -4002 Plovdiv, Bulgaria

The acute orofacial infections often are therapeutical problem. The complex treatment of such patients include antimicrobial agents, surgical intervention, immunostimulation with Oxyrich and laser therapy.

Laser system "Six - L - IR" class IIIB, with active medium GaAs, l0w peak power, 904 nm was used. Two methods were applied: 1) distant, local with 100% power, 4000 Hz per 5 min and 400 Hz per 3 min and 2) laser punction for 60 sec in BAP V43, GI4, T14, E36 and point 55 of the ear. Patients were treated for 10 days.
33 patients were tested for their phagocyte activity before and after the treatment. Nitro - blau - tetrazolium test (NBT) for enzymatic activity of the leucocytes was included also. The antiinflammatory and biostimulating effect of the laser therapy is discussed.
These preliminary results emphasize the positive results from complex therapy including laser puncture and immunostimulators in patients with acute orofacial infections

5) Low level laser in the treatment of ulcus cruris

Z. Trojacanec, S. Nikolic, Z. Handziski Institute of ME Physiology, Faculty of Medicine, Skopje, FYROM

Ulcus cruris is a complication following deep vein incompetence and the terms "postphlebetic leg" or "stasis syndrome" are applied. The ulceration is usually small, superficial, and very painful because of exposure of nerve endings. Varicose veins may be seen or palpated close to or continuous with the ulcer. These ulcerations may start after minor trauma to an area of pigmentation, induration, eczema, or edema, and are usually chronic by the time they are seen.
The influence of low level laser under the skin has been examined in large number of laboratory and clinical studies, considering that the skin is a big area for absorbing a great amount of photons. The aim of the study was to explore the role of low level laser in the treatment of slowly healing ulcus cruris. Ten patients with slowly healing ulcus cruris have been treated with helium-neon laser type "Bistra" with wavelength 630 nm, average output 15 mW and an irradiance of 250 mW/cm2. All patients have been previously treated with other therapeutic modalities for six months but without result. Complete healing was achieved in eight patients and two patients showed significant diminution of their lesions. Irradia laser treatment may be a valuable therapy in dermatologic diseases, especially in slowly healing wounds

Reports from The IXX Annual Meeting of The American Society for Laser Medicine and Surgery, Lake Buena Vista, Florida. April 16-18, 1999. Lasers in Surgery and Medicine. Supplement 11, 1999.

1. Report on more than eight years of low level laser therapy of chronic inner ear diseases. Lutz Wilden, Sabine Schübel, Germany. 348 patients (402 ears) were treated with low level laser. Most patients had tinnitus. This study, however, only reports on the objective outcome of the audiometry, taken before and after therapy. The hearing capacity of the patients was improved in all frequency sectors (average value = 20.6%). The best db-reductions were obtained in the low frequencty sector (11.7 db) and in the high frequency sector (14.6 db). There was a close correlation between the improvement of the hearing capacity and the age of the patients and the duration of their disease. In conclusion it can be stated that if LLLT is administred in sufficiently high dosages to the inner ear (cochlea), it is possible to obtain and document significant biostimulative effects.
   
   
2. Lack of stimulatory effect of laser irradiation 660 nm at various radiant exposures upon a radiation impaired wound healing model in murine skin. Lowe A S et al, N. Ireland. Experimental wounds in radiation-impaired (20 Gy) murine skin was exposed to 0.5, 1.5 or 4.0 J/cm2 660 nm laser irradiation three times weekly until closure was complete (15 mW, 5 Hz). Wound size was analysed using a video image analysis system. No evidence of stimulatory effects could be observed at these parameters.
   
   
3. The effect of low-level laser irradiation on lymphocytes from peripheral blood. Stadler I et al, New York, USA. Lymphocyte suspensions were irradiated with argon-dye laser (660 nm) or diode laser (830 nm) at doses varying from 0-5 J/cm2 in the abscence or presence of erythrocytes. Irradiation at 660 nm in the precence of erythrocytes significantly enhanced the proliferation response of lymphocytes. The maximal response was detected at 3 J/cm2. Laser irradiation at 830 nm resulted in a maximal interaction at fluences of 1.5 J/cm2. In abscence of erythrocytes the effect of irradiation showed a weak dose-response relation. No significant change could be detected in cell mediated cytotoxicity. The results indicate that the catalyzed reactive-oxygen-substances play an integral role in laser light interaction with whole blood.
   
   
4. Soft tissue injury during sport activities and traffic accidents - treatment with low level laser therapy: A multicenter double blind, placebo controlled clinical study on 132 patients. Simunovic Z, Trobonjaca T, Switzerland/Croatia. 132 patients were treated with lllt as a monotherapy. Indications were distortion and sprain of the ankle; lesion of the Achilles tendon; dislocation of the knee, shoulder and interfalangeal joints; wrist and cervical spine injuries and both types of epicondylitis. All patients represented acute cases. Two types of irradiation techniques were used: skin contact for trigger points (830 nm) and scanning technique (633/904) for larger surface areas. The laser group was compared to a group of patients treated with conventional therapies. In the lllt group the recovery progress was accelerated by 35-50% in 85% of the patients, as compared to the control group. More abstracts will follow

Low-energy laser irradiation affects satellite cell proliferation and differentiation in vitro. Ben-Dov N et al. Biochimica et Biophysica Acta. 1999- 1448: 372-380.

Here are some selected mini-abstracts from the 2nd Congress World Association for Laser Therapy, September 2-5, 1998. Kansas City, MO, USA.

Onac compared the effect of HeNe laser and monochromatic light at 618 nm.
The intact skin of guinea pigs was irradiated with different doses. The monochromatic light had similar effects as that of HeNe, but weaker. Further on, monochromatic light at low doses had no effect at all and at high doses caused nodular hyperplasia and focal epidermic hypertrophy. Thus, the therapeutic window seems to be narrow for monochromatic light. Onac I et al. Histological study regarding the effects of He-Ne (632.8 nm) laser biostimulation upon the tegument of Cavia Cobaia as compared with that of monochromatic red light (618 nm). Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 52-53.

Asagai reports on the use of GaAlAs (100 mW) laser treatment in a group of 1000 patients with cerebral palsy.
The laser reduces muscle spasm and increases the mobility of the muscles. Although the duration of the LLLT effect was limited to one to several hours, it can be applied in conjunction with conventional functional therapies, thereby enhancing the effects of the latter. Asagai Y et al. Application of low reactive-level laser therapy (LLLT) in the functional training of cerebral palsy patients. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 99-100.

Katsuyama studied the effect of 830 nm laser in a neuropathic pain model of rat.
The left side sciatic nerves of two groups of rats were ligated loosely to produce a neuropathic pain. The latency of the foot withdrawal reflex to noxious heat stimuli was measured before the ligation, immediately after laser/placebo radiation and at 14 days after ligation. The laser group received 72 J through the dermis. This group showed a significant reduction in lef foot withdrawal immediately after irradiation and at 14 days, the right foot being unchanged. Placebo irradiation did not change the latency in the ligated in the ligated group, nor in non-ligated rats. Katsuyama I et al. Laser irradiation suppresses hyperalgesia in neuropathic rats. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 28

Phantom pain after amputations is a severe problem.
Taguchi reports that laser therapy has been the most effective way of releasing the phantom pain of an amputee. Taguchi Y. Clinical experiences of laser applications in physical therapy. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 106

In a study by Amaral 15 mice received a single muscular injection of myotoxin
in the tibialis anterior muscle of both legs.
One group received HeNe 2.6 J, another 8.4 and the third 25 J/cm2 on one leg, while the other was sham irradiated. The 2.6 J group showed a significant difference with evidence of a greater concentration of mitochondria in the treated muscle, whereas the higher doses did not produce this effect.The laser treated mice also showed an increase of cross-section area of the muscle fibers. Amaral A C et al. He-Ne laser action in the regeneration of the tibialis anterior muscle of mice. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; pp 18-19.

In an animal study by Kobayashi the effect of GaAlAs laser on the blood flow in flaps was studied through laser speckle flowgraphy (LSF).
40 rats were divided into four groups. Two groups had random pattern flaps, two had axillary pattern flaps with the dominant vessels intact. Flaps were raised and peripheral blood flow assessed through LSF. Laser irradiation was performed in two groups, either directly on the dominant vessel or at one point on the distal part of the flap. The blood flow directly after irradiation was higher than before irradiation. At day 5 there was a clear difference between the irradiated and the non-irradiated flaps. The flaps irradiated at the dominant vessels had a slightly better outcome than those irradiated at the Kobayashi M et al. Studies of the diode laser therapy on blood supply in the rat model. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 70-71.

Schindl treated a chronic radiation ulcer with HeNe laser, 30 J/cm2.
A video measuring system was used to deterime the number of dermal vessels in the ulcer before and after the laser treatment. After 7 irradiations the ulcer had healed completely. Light microscopy in combination with the video measuring system showed a significant increase in the number of capillaries after laser treatment. Schindl A et al. Increased dermal neovascularization after low dose laser therapy of chronic radiation ulcer determined by a video measuring system. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 34

55 patients with long lasting chronic venous ulcers, suffering for more than 6 months without improvement, were treated with LLLT by Lichtenstein .
42 patients were treated with HeNe, 13 with 780 nm GaAlAs. The follow-up ranged from 6 months to 6 years. Wound closure was achieved after 7 to 40 treatments in most of the patients. Complete healing was achieved in 47 patients and moderate improvment in 4 patients. LLLT was used in parallell Lichtenstein D., Morga B. Laser therapy in ambulatory patients with venous stasis ulcers. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 31-32.

In a study extended over 6 years Soriano treated 231 patients with venous leg ulcers.
The exclusion criterias were diabetes, arterial disease, vasculitis, congestive heart failure and loss of follow up at 6 months. 122 of 154 patients in the laser group fulfilled the study. In the control group (traditional treatment only) 46 of 77 patients fulfilled. Wounds were all of Size Rate 4 or larger (diameter major + diameter minor). A 40 mW GaAs laser at 10.000 Hz was used, The laser was applied in the point technique with a dose of 3 J/cm2 per point around the border and onto the bed of the ulcer in non contact. Three sessions a week were performed for 4 months, or until the ulcer was completely healed. The results were evaluated as complete healing, partial healing (more than 50%) or non healing (less than 50%). In the laser group there was a 70% healing rate and a 14% rate of partial healing. In the control group 26% of the patients had a complete healing and 22% a partial healing. In the laser group, only 19% of the ulcers of great size (>16) healed completely and if the wound was more than one year old, the percentage of complete healing was 40%. Wounds with an oedema failed to heal with the parameters used. Soriano F. GaAs laser treatment of venous ulcers. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 128-130.

The effect of different approaches for laser therapy of acute nonspecific epididymitis was studied by Gomberg .
In a previous study by Reznikov [682], transscrotal HeNe irradiation had proved beneficial. Gomberg compared transscrotal, endolymphatic and laser acupuncture for the treatment of a group of 28 patients. The endolymphatic treatment was performed via a small quartz fiber, inserted into the regional lymphatic node, 0.15 J in total. The transdermal dose was maximum 2.7 J. Laserpuncture (Hegu and Zusanli) was performed using a miximum of 30 J per point. The clinical outcome as well as the polymorphoneucleocyte/lymphocyte index, main population and subpopulations of lymphocytes were evaluated. Endolymphatic irradiation was found to be more efficient than trans-scrotal laser therpay. The former required 4 procedures each with an interval of 24 hours, whereas trans-scrotal irradiation required 1-3 days longer. Laser acupuncture was not effective. Gomberg V G et al. Endolymphatic laser therapy in management of acute nonspecific epididymitis. Proc. 2nd Congress World Assn for Laser Therapy, Kansas City, September 1998; p. 27