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LaserWorld Guest Editorial,Nr 8 - 2000.
Low-level laser therapy after molar extraction
By Hana Kucerováa, Tatjana Dostálováa, Lucie Himmlováa, Jirina Bártováa, Jirí Mazánekb
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LaserWorld Guest Editorial,Nr 8 - 2000.


Low-level laser therapy after molar extraction

Hana Kucerováa, Tatjana Dostálováa, Lucie Himmlováa, Jirina Bártováa, Jirí Mazánekb

aInstitute of Dental Research - General Medical Hospital, Vinohradská 48, 120 60 Prague 2, Czech Republic,
E-Mail: dostalova@vus.cz

bFirst Medical Faculty of Charles University Prague, Czech Republic


The aim of the study was to evaluate the different frequencies of low-level laser radiation (diode - 670 nm and Helium-Neon 632,8 nm) on healing process after human molar extractions. Frequencies of 5 Hz, 292 Hz and 9000 Hz were used in experiments. Monitoring of secretory IgA and albumin level in saliva and changes in bone density were used as objective markers of biostimulatory effect. Subjective evaluation of therapy was observed using scale (from - negative therapeutic effect; ++++ excellent treatment effect). Changes of sIgA, albumin levels and bone density were compared in group of 150 patients (non-laser therapy - 30 patients). Differences in levels of the saliva markers (sIgA and albumin) were found to be significant comparing irradiated and non-irradiated groups, as well as comparing groups irradiated by various modulatory frequencies. It was observed significant differences between increase of sIgA res. albumin and subjective treatment feelings. Bone density after extraction and six-months after surgical treatment was examined using the dental digital radiovisiography. There were detected no significant differences between bone density in irradiated and non-irradiated groups perhaps due to our used therapy diagram.

Keywords: dentistry, low-level laser radiation, secretory IgA, albumin,

Extractions of teeth are a part of the dentist's everyday work in his office. It exists many reason for tooth extraction e.g. carries, periodontal diseases, retention or semi-retention tooth etc. After extraction we observe the wound and wound healing is one of the fundamental biological processes allowing the preservation of organism after tissue damage 1,2. Regeneration takes place in three overlapping phases 3.

  • inflammatory phase: lasts several hours, the damaged tissue is infiltrated with the leukocytes and makrophages infiltration and fibroblasts migration, which also occurs and lasts from 1 to 3 days

  • proliferation phase: between second and fourth day - neovascularisation, type III collagen synthesis occurs between day 2 and 16.

  • tissue reconstruction phase: in day 9 to 60 the type III collagen is replaced with type I, the amount of blood vessels is reduced and the reconstruction of fibrous tissue than continues for 6 to 12 months3.

After the extraction the open space of spongiosis is filled with blood clot. The vein re-growth is followed by cells from healing bone marrow. These cells are changed to osteoblasts. The bone is gradually strengthened by lamellar bone. This primary spongiosis structure is, depending on the local conditions, transformed into compact cortical orlamellar bone. The formation of cortical layer, secondary spongiosis and marrow spaces takes approximately 4 months. The final phase of bone differentiation then takes place, where bone is re-modeled into Haversian systems and secondary osteons appear. The re-modellation proceeds from the defect bottom and edges into the central part of the wound. In the extraction pocket the neovascularisation starts. The oxygen supply increases. The oxygen is needed for collagen synthesis and wound epithelisation 4,5 . The components needed for collagen synthesis are provided by phagocytes via damaged tissue. Consecutively, the collagen is transformed into a specific form, the further cell dividing stops, and the veins created by neovascularisation are reduced. The wound surface is epithelised, and the tissue is healed 4.

A normal consequence of using elevators during extractions is that neighouring teeth become sensitive and are difficult to chew with. From literature is known that after extraction the alveolus is irradiated along with the lingual and buccal bony wall 6. Faster coagulation, less postoperative discomfort and quicker healing could be expected 7,8, 9. In our study we decided to objectively evaluate the real effect of low-level laser radiation on healing process after human lower molars extraction 1,3,5, 7,8,9,10. The goal of study was to determine the effects of different frequencies on the healing of extraction wounds via monitoring the changes in secretory IgA and albumin levels in saliva before and after extraction and to evaluate the effects of laser therapy on the healing process of the bone wound via comparing the bone density of laser therapy-treated groups of patients and a group who did not receive any laser therapy treatment in comparison with subjective feeling of patients 1,3,8,9,10,11,12,13.

Low-level diode laser MED 100N (Lasotronic, Zug, Switzerland, diode GaAlAs, wavelength 670 nm, power output 20 mW) and He-Ne Biostimul laser (Medicom, Prague, Czech Republic, wavelength 632,8 nm, output 5 mW) were used to laser therapy (Fig. 1). We used the following laser frequencies:

  • diode laser MED 100N, frequency 292 Hz

  • diode laser MED 100N, frequency 9000 Hz

  • diode laser MED 100N, frequency 5 Hz

  • He-Ne laser Biostimul, frequency 5 Hz

  • control group - no laser radiation.

The use of low-level lasers is currently quite wide-spread in the dentistry offices 2,13. These lasers are usually equipped with not only the continuous beam but also with the adjustable frequency setting. Often enough, they have pre-set Nogier frequencies, Mastalier-adjusted for dentistry (A=292Hz, B=584Hz, C=1168Hz, D=2336Hz, E=4672Hz, F=9344Hz, G=146Hz). The available knowledge in the field of biostimulatory laser therapy do not give a clear-cut answer to the question what is better for the organism: to use continuous beam, to switch among several different frequencies, or to use a beam modulated into an exact frequency. Recommended frequency levels for diagnoses in dentistry that can be found in the literature either are modulated to a exact frequency or do not precise the beam type used : E.g. for the healing of extraction wounds you can find the following options:

  • Smékal, Mašková: continuous (CW) beam, 5Hz

  • Mastelier: 292Hz - "A" frequency per Nogier

  • 3000-9000Hz per Navrátil

  • 9300Hz per the guidebook for Oralaser Oralia Konstanz Switzerland

We focused on monitoring.150 healthy patients between 18 and 65 years old, after the extraction of their lower molars (reason for extraction: semi-retention of third bottom molars, carries of teeth 48,47,46,36,37,38). All patients, including the control group, were briefly informed about the anti-inflammatory, analgesic, regeneratory, and immunomodulatory effects of the laser before its use. In accordance with the 1964 and 1989 Helsinki Declaration they gave an informed agreement to cooperate on this project. Patients were randomly divided into five groups. The patients in every group were after extraction treated with low-level diode laser or read light (group 5 - placebo effect)

  • Group 1 (30 patients) - low-level diode laser MED 100N, (LASOTRONIC, Zug, Switzerland), frequency, 292Hz, (diode GaAIAs, wavelength 670nm, power output 20mW), density 1,5 J/ cm2

  • Group 2 (30 patients) - low-level diode laser MED 100N, (LASOTRONIC, Zug, Switzerland), frequency, 9000 Hz, (diode GaAIAs, wavelength 670nm, power output 20mW), density 1,5 J/ cm2

  • Group 3 (30 patients) - low-level diode laser MED 100N, (LASOTRONIC, Zug, Switzerland), frequency 5Hz, (diode GaAIAs, wavelength 670nm, power output 20mW), density 1,5 /J cm2

  • Group 4 ( 30 patients) - He-Ne Biostimul laser (MEDICOM, Prague, Czech Republic, wavelength 632,8nm, output 5mW), frequency 5Hz, density 1, 5 J/ cm2

  • Group 5, control (30 patients), was not laser-treated at all following the extraction.

Extraction procedure
We have applied local anesthesia (Supracain, Léciva, Czech Rep., Mepivastesin, ESPE, BRD) and extracted the molar. We were used scissors and (or) elevators. Immediately after the extraction, we have irradiated the patients in the groups 1 - 4 with the respective lasers and respective frequencies and energy density 1,5 J/cm2 1,9. The alveolus was irradiated along with the lingual and buccal bony wall. We added the dose into the central part of the wound. The patients were then irradiated with laser for next 4 days.

Determining sIgA and albumin levels
An unstimulated saliva sample (approx. 1 - 1,5ml) was received from each patient prior to the treatment and on the fifth day. Quantitative determination of the secretory IgA and albumin was based on the principle of radial diffusion of saliva sIgA or albumin from the circular pit into a layer of agar gel containing monospecific antagonist. The resulting circular precipitate was evaluated after 96 hours, when a final point of immunodiffusion is achieved. The size of the ring is dependent on the concentration of the proving protein, in our case sIgA and albumin. The concentration of the sample is read directly from the reference table in the kit. Usage of the commerce kit Binding Site allows fast determination of sIgA and albumin in the saliva and guarantees reproducibility and standardization of the method. The sIgA and albumin levels after the treatment were referenced against the levels obtained from the first saliva sample and expressed in percent using the test of Student at the significance level P=0,05. The level of the first sample was considered as 100% (Fig.2).

Bone Density
As an additional marker for analysis of laser biostimulatory effect we evaluated the changes in bone density 6 months after extraction. To obtain the X-ray image, we have used the dental digital radiography method (Radio Visio Graph - RVG, Trophy, France). Isometric images were captured to have possibility to compare the measurements via fixed-point measurement method. We can measure up to 7 specific dimensions. The method itself is non-invasive, since it takes only 15% of the radiation exposure to obtain one conventional X-ray picture 14.

For evaluation we have used digital images taken immediately after the extraction and consecutively after 6 months. To capture the integration in the entire area of the extraction wound we have used the method of sliced RVG images, which we have taken laterally through the extraction wound 7. For that reason we have taken 3-5 slices, depending on the extraction bone area. The slices were 2 mm apart. For each slice, we have established density histogram, characterizing the density spread across the slice. Histograms were evaluated using the computer software program Sigma Scan and Sigma Scan Pro (Jandel, Germany) (Fig. 3).

Subjective patient's response to treatment

To evaluate less postoperative discomfort we prepared the special card containing relevant information on the patients: personal and health information, type of tooth and 5 degree scale of patient ´s sensation from - no change to ++++ excellent results:

- no change

+ less postoperative disconfort

++ better subjective feeling

+++ best subjective feeling

++++ exellent result

RESULTS SIgA and albumin levels:
It was found the significant difference between patients irradiated by laser and control group (Graf 1.) The levels of sIgA and albumin increased in comparison to control. Comparison of the control group with the laser therapy treated patients groups irradiated by various frequencies (Graph 2) shows the most significant increase in the case of patients treated with laser frequency 292 Hz, 9000 Hz and for both the albumin levels and sIgA levels and for 5 Hz for sIgA level. Bone density: The results are in graph form, which compiles the density levels of individual slices for patients after extraction and after 6 months as well as the difference between these two periods (Graph 3). The treatment methods we have used (extraction wounds treated with 1,5 J/cm2 load for 4 days following the extraction) have not shown any significant differences in the bone density compared to the control group 12.

Subjective patient's response to treatment

The better patient ´s sensation after laser therapy was observed. The patients felt more comfort after laser therapy for all types of laser and different frequencies (Graph 4).

The low-level laser has no influence on the process of osseintegration. This effect was observed on fracture healing in rats using He-Ne laser radiation 12. We have not found any differences in the bone density compared to the control group. Frequencies recommended for wound healing in literature often vary 1,8,9,10,. Different frequencies can have varying effect on sIgA and albumin levels 8,9,15. It is therefore important to use frequencies that increase both sIgA and albumin levels or at least don't have a negative effect. We have found significant differences in sIgA and albumin levels between patients exposed to radiation and those who were not. The highest increase in sIgA and albumin levels were found in the group treated with the frequency of 9000Hz. Increase in the level of markers vs. the control group was found even in groups treated with other frequencies (5Hz, 292Hz). Laser therapy objectively improves extraction wound healing and can be recommended as a method of choice16,17. We regard healing of extraction wounds with laser as contributory not only due to subjective feelings of patients who accept laser therapy largely positive due to its non-invasiveness and non-painfulness, but also due to the objectively proven changes in sIgA and albumin levels 8,15.

This research has been supported by the Grant Agency Ministry of Health of Czech Rep. No. 4091-3.


  1. Z.Hložek, J. Hubácek : "Immunostimulatory effect of He-ne laser", Digest of lectures, Proseedings VII of Chvojka day, Olomouc 1995, 7, 65-80.
  2. L.Navrátil, J.Hubácek : " Basic knowledge about biological effect of non-invasive laserotherapy", Non-invasive laserotherapy, Praha, Czech rep., Manus, 1997, 31-51.
  3. J. Pospíšilová : "Healing of wounds", Acta chir. Plast., 1982, 24, 293-303.
  4. M.A. Porgel, Ji Wei Chen, Ken Zhang, : "Effects of Low-Energy Gallium-Aluminum-Arsenide Laser Irradiation on Cultured Fibroblastsand Keratinocytes", Las. Surg. Med., 1997, 4, 426-432.
  5. T.Karu : " Molekular mechanism at the therapeutic effect of low intensity laser radiation", Laser in Life Science 1988, 2, 53-74.
  6. M.Verpanken : Stimulation of wound healing after tooth extraction using low intensity laser therapy, Revue Belge de Medicine Dentaire, 1987,42,134.
  7. S.Fernando et al : "A randomised double blind comparative study of LLLT following surgical extraction of lower third molar teeth", Br. j. Oral. Maxillofac. Surg., 1993, 31,3,170-172.
  8. V.Mašková, M.Smékal : "Possibility using of lasers in dentistry", Cs. stomat., 1991,91,1, 57-64.
  9. L.Navrátil, P. Kuna et al :" Non-invasive laserotherapy ", Praha , Manus, 1997, 5-148.
  10. E.J.Neiburger :" The effect of low laser on intraoral wound healing", N.Y. State. Dent. J., 1995, 61,3,40-43.
  11. .J. Tunér, L. Hode : "It's All in The Parameters: A Critical Analysis of Some Well-Known Negative Studies on Low-Level Laser Therapy ", J. Clin. Las. Med. Surg., 1998, 16, 5, 245-248.
  12. R.David, M.Nissan, I.Cohen, M.Soudry : " Effect of Low-Power He-Ne Laser on Fracture Healing in Rats", Lasers in Surgery and Medicine, 1996,19, 458-464.
  13. A. K.Roynesdaj :" The effect of soft laser application on postoperative pain and swelling ", Int. J. Oral. Maxillofac. Surg., 1993,22,4,242-245.
  14. M.E.Dagenais,B.G.Clark :"Receiver operating characteristics of Radio Visio Graphy ", Oral-Surg-Oral-Med-oral-Pathol., 1995, 79,2,238-245.
  15. E.E.Sagalovich : "Secretory immunity changes in patients with acute and chronic herpetic stomatitis by laser therapy ", Clinical immunology and immunopathology, 1995, 1,7, 385.
  16. M.Verpanken :" Stimulation of wound healing after tooth extraction using low intensity laser therapy " , Revue Belge de Medicine Dentaire, 1987,42,134.
  17. G.Wahl, S.Bastianer : "Soft laser in postoperative care in dentoalveolar treatment", ZWR. 1991,100,8,512-515.


Fig. 1. Low-level diode laser MED 100N (Lasotronic, Zug, Switzerland, diode GaAlAs, wavelength 670 nm, power output 20 mW) and He-Ne Biostimul laser (Medicom, Prague, Czech Republic, wavelength 632,8 nm, output 5 mW)

Fig. 2. Radial diffusion of saliva sIgA or albumin.

Fig. 3. Changes in bone density immediately and  6 months after extraction.

Graph 1.: Secretory IgA and albumin after treatment in relation to their values before treatment.

Graph 2.: Secretory IgA and albumin after treatment in relation to their values before treatment.

Graph 3.: Bone density

Graph 4.: Subjective effect of laser irradiation


Editors note
To promote bone generation repeated irradiation is necessary. The alveolar bone will be healed at 6 months post extraction with or without laser. The interesting matter is the development during the early months and the time when laser treated bone would be of the same quality as non-lased bone at 6 months.

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