Dr. Rosane Lizarelli, D.D.S., Riberao Preto, SP, Brazílie

E-mail: lizarelli@neomundi.com.br

Published jointly in Laser Partner and Laser World (www.laser.nu)

 

Abstract

 

The possibility of reducing the patients' pain and anxiety through low level laser applications has been the main objective of my research within laser therapy. This Editorial deals with the low level laser as an indispensable and irreplaceable tool for the dentist nowadays in the dental office, focusing on an innovative operator modality: its preventive performance.

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Clinically, the use of low level laser therapy has demonstrated excellent results. In terms of tissue healing, largely discussed, it shows evidence of the acceleration process in up to three times, mainly for those patients with physiological disturbances,. This may be considered as an indispensable and preventive procedure. Furthermore, the patient's temporary dysfunction, provoked by a wound, being surgically or not, is reduced. This fact causes a comfort that can be achieved only by low level laser.

My double-blinded study compared a group without laser and with systemic analgesic medication with two other groups with laser: one group with laser only after the surgical procedure and the other with laser therapy before and after the surgery. This study clarified that 790 nm laser therapy with a dose of 1,5 J/cm2 was as effective with regards to the analgesic and anti-inflammatory effect as conventional medication, both for the pain and oedema control.

To accomplish the present study, 45 clinical situations were selected during the Graduation Course of in Implant and Prosthesis of 3i Implants Innovations, Inc., in Ribeirão Preto, São Paulo, Brazil. The selection approach was just constituted in writing in the consent on the part of the patient taking the responsibility in coming back for the follow up care, and also in executing the rules imposed by the methodology of the research. To all the patients it was instituted a systemic medication of preventive anti-bioticotherapy was instituted and also continued after the surgical procedure for 6 days to the base of penicillin, and for the allergic ones, to the clindamicin base.

The piece of equipment of low powered laser chosen was a semiconductor diode of GaAlAs (galium, aluminum and arsenium), that emits in the infra-red close with wavelength of 790 nm and pick power of 30 mW. The emission type is continuous and the application form should be accomplished contacting the gingival tissue; the area of the active point of the crystal of quartz is of 0.13 cm2 (Compact Laser, J. Morita Co., Japan).

The patients were divided in three different groups, constituted of 15 clinical situations each one, as follows:

• Group I: Control, the laser application was simulated, without working the "start", just leaving a "bip" ring. All the patients from that group received that simulation during one minute scanning the operated area. Those patient were well informed with the analgesic and anti-inflammatory systemic medication to the piroxican base (Cicladol 20 mg) twice a day in the postoperative for a period of three days.
• Group II: Lasertherapy sessions in the postoperative immediate, of 24 hs and of 48 hs. It was not instituted the analgesic and anti-inflammatory systemic medication.
• Group III: Lasertherapy sessions in the pre-operative of -48 hs, -24 hs and minutes before the surgical intervention and also in the postoperative in the same way that in the Group II. The patients were equally well educated and have not taken the analgesic and anti-inflammatory systemic medication.
  

The Group III was elaborated based in NICCOLI FILHO's studies (1995) that used the low power of density laser radiation with prevention.

All the applications were accomplished using the same energy parameters and for the same operator and the way of the application was accomplished sweeping the whole area of the tissue to be irradiated, which should be dry preferentially to allow the minimum reflection of the light for the energy not to be lost and absorbed by the tissue. The point of the equipment that contacted the tissue was involved with plastic by hygiene measure and of infection control (in the same way as it is made clinically) which promotes the loss of 10% of energy, that however is not important.

The time of each application was calculated in agreement with the formula of density power ( or intensity). The area of each clinical situation had been calculated associating the clinical exam to the radiographic, determining the same for the probable operative field that would be explored. The chosen energy was based on the studies of Kubasova that says the energy of 0.5 to 5.0 J/cm2 is enough for obtaining of the analgesia effects and of bioestimulation effects. Being like this, the chosen energy density was of 1.5 J/cm2.

The measures, with relationship to the pain and the edema, were accomplished in the immediate postoperative and in the postoperative of 72 hours, always for the same examiner. The examiner asked the patient previously to the laser application what the pain degree was in that moment considering the values of the table 1. with relationship to the edema analysis, the examiner checked the value to each case, according to the table 2.

When we irradiated the area to be operated, like suggested by Niccoli Filho (1995), we believed that we were "preparing" the cells, mainly for the chemical mediators liberation, especially for the histamine, which acts by increasing the vascular permeability. According to Ovsiannikov, this procedure stimulates the immune system. Mikailov and Denisov compared three groups of 112 patients with stages IV of stomach cancer; 32 patients received LLLT before surgery, 38 received it after surgery, and 29 patients did not receive LLLT at all. The laser therapy before the operation was slightly more effective. LLLT increased T-active rosette cells and T-helpers, and decreased T-suppressor cells. The life span of the LLLT patients, as compared to the control group increased by a factor of 2 if surgery was performed and by a factor of 3 if surgery was not performed.

The statistical analysis was just accomplished to check the clearly observed clinical discoveries scientifically. The non-parametric Test of Wilcoxon which compares equal of samples, and with significance degree at level of 5.0% (Tab. 3) was chosen.

With relationship to the painful sensitivity, when we compared GI with GII, and GI with GIII, so much in the immediate postoperative as in the postoperative of 72 hours, we observed there were not significant statistical differences.

Even so, in the immediate postoperative, GIII shows a tendency in being significant, suggesting a superior behavior to GII.

With relationship to the edematous formation, we compared GI with GIII, so much in the immediate postoperative as in the postoperative of 72 hours, we didn't observe significant statistical difference; differently to what we compared, in that situation, GI with GII, where a great tendency to the significance happens.

Table 3 - Statistical results with significance degree at level of 5.0%, when Tc = 138

Event	Samples Pairs	Immediate PO	PO of 72 hours
Pain	GI - GII GI - GIII	| 45.5 | | 107.5 |	| 67.5 | | 22.5 |
Edema	GI - GII GI - GIII	| 133.5 | | 42.0 |	| 135.0 | | 90.0 |

In agreement with the applied methodology and with the obtained results, the use of low power density laser in implanted patients suggested:

1 - A similar behavior to the analgesic and anti-inflammatory systemic medication, suggesting the possibility of replacement;

2 - for pain control, lasertherapy sessions in the pre-operative were more effective than the postoperative lasertherapy sessions, as executed in GIII;

3 - for tumor formation control, lasertherapy sessions in the postoperative were enough, as executed in GII. Cells with acid pH are more susceptible to light. Furthermore, the possible mechanism at a cellular level probably is depending on the monochromatic carachter of the light, which the organisms are not adapted to evolutionwise. Thus, laser light is one of the environment factors (external agents) capable of modifying the cellular proliferation. The stimulus or inhibition caused by the light may be regarded as a sensorial answer to accommodate to the environmental conditions.

So the question is: why don't we prepare the target tissue through low level laser irradiation as a preventive procedure prior to the trauma?

References

1. KARU, T. I. Photobiological fundamentals of low-power laser therapy". Journal of Quantum Eletronics, v. QE-23, 10, October, 1987.
2. KARU, T. I. Molecular mechanism of the therapeutic effect of low-intensity laser radiation. Lasers in the Life Sciences; 2(1): 53-74, 1988.
3. 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, Proc SPIE Vol. 3593, p. 49-56, 1999.
4. LIZARELLI, R. F. Z.; CICONELLI, K. P. C.; BRAGA, C. A.; BERRO, R. J. Low-powered laser therapy associated to oral Implantology. in Lasers in Dentistry V, John D. B. Featherstone, Peter Rechmann, D.D.S., Daniel Fried, Editors, Proc SPIE Vol. 3593, p. 69-73, 1999.
5. NAVRATIL, L.; DYLEVSKY, I. Mechanisms of the analgesic effect of therapeutic lasers in vivo. Laser Therapy, 9: 33-40, 1997.
6. NICCOLI FILHO, W. D. Eficácia da radiação de dois diferentes tipos de laser de baixa energia (HeNe e GaAlAs) na prevenção de mucosites orais em pacientes submetidos a transplantes de medula óssea. Tese de Livre Docéncia. São José dos Campos: Faculdade de Odontologia de São José dos Campos UNESP, 1995. 68p.
7. OVSIANNIKOV, V. A. Analysis of the low-energy laser treatment of some cancers and infections diseases. Journal of Clinical Laser Medicine and Surgery, 15(1):39-44, 1997.
8. MIKHAILOV, V. A., DENISOV, I. N. Activation of the immune system by low level laser therapy (LLLT) for treating patients with stomach cancer in advanced form. Laser and Technology;7,(1): 31-44, 1997.