The Journal of Japan Society for Laser Surgery and Medicine

The Effect of High-intensity Laser Pulses for Cell Death in Photodynamic Therapy

Yuuichi MIYAMOTO, Yukihiro UMEBAYASHI, Tsuyoshi NISHISAKA

1999 Volume 20 Issue 1 Pages 1-8
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_1

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A study was conducted in the HeLa cells which were incubated with the hematoporphyrin derivative (HpD) for 1h (1μg/ml of HpD in PBS) to compare continuous wave (CW) and pulsed laser (10Hz repetition rate and 7-9 nsec pulse width) light for photodynamic therapy. Cytotoxic effects on the cells were evaluated by fluorescein diacetate (FDA)/propidium iodide (PI) stain method using a flow cytometer. The estimation of the type of cell death was performed by the analysis of the DNA content and observation of the nucleus morphology. The cytotoxicity ratio of the cells irradiated by the pulsed laser light was estimated to be lower than that of the CW laser light. The type of cell death was different between the pulsed and CW laser light. These findings revealed that the cytotoxic effects of the excitation light source were expressed by the difference in the type of cell death namely apoptosis or necrosis.

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[title in Japanese]

[in Japanese]

1999 Volume 20 Issue 1 Pages 9-10
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_9

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Application of Laser to Dental Implants

Hiroshi SHIMIZU, Naoyuki TAGUCHI, Haruka KUSAKARI

1999 Volume 20 Issue 1 Pages 11-19
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_11

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The purpose of this study is to evaluate the effect of low power laser on bone formation, wound healing of gingiva surrounding inserted implants and to assess CO₂ laser ability to eliminate bacteria from titanium implant surface.
The studies about low power laser showed as follows. Laser promotes the turnover rate of bone resorption, sequentially bone formation and collagen, during the initial healing stage in vivo. And laser stimulates DNA and expression of ALP activity in vitro. These results suggest that the low power laser irradiation exerts beneficial effects on wound healing of bone and gingiva.
In the study of CO₂ laser, S. sanguis and P. gingivalis were killed entirely by the irradiation at 286 and 245J/cm², respectively. Laser irradiation did not cause surface alteration, and rise of temperature. And it did not give rise to serious damage of connective tissue cells located around the contaminant area and inhibition of cell adhesion to irradiated area. These results suggest that CO₂ laser irradiation may be useful in removing bacterial contaminants from titanium implant surface.

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Current Status of Laser Application in Periodontics

Isao ISHIKAWA, Akira AOKI

1999 Volume 20 Issue 1 Pages 21-29
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_21

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Based on the various characteristics such as ablation or vaporization, hemostasis, and sterilization effect, laser treatment has been expected to serve as an alternative or adjunctive therapy to the conventional, mechanical instrumentation in periodontal therapy. The CO₂ and Nd: YAG lasers have been approved for soft tissue treatment in periodontics and oral surgery because of their excellent ability for soft tissue ablation accompanied by hemostatic effect. However, these lasers have not shown an effectiveness for the treatment of hard tissues such as the root surface and alveolar bone due to major thermal side-effects to the target and surrounding tissues. Therefore, in periodontics the use of these laser systems has been limited in the soft tissue surgery. Recently, the use of Er: YAG laser has been developed in dentistry and its excellent ability for both of soft and hard tissue ablation has been revealed. The appearance of the Er: YAG laser, of which promising characteristic shows high absorbability in water, has increased laser applications in periodontal treatment as well as in dental caries treatment. In this communication, we report our basic and clinical studies on the Er: YAG laser application to scaling, soft tissue removal, and bone surgery.

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New Trend of Laser Application in Endodontics

Hideaki SUDA

1999 Volume 20 Issue 1 Pages 31-38
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_31

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This article summarizes the new trend of laser application in endodontics. Er: YAG laser is promising in cavity preparation because of its disinfecting and tooth cutting abilities, low noise, less pain and no vibration. Laser is also used for measuring pulpal blood flow. In traumatized and/or developing teeth, laser Doppler flowmetry is sometimes the only method to diagnose tooth pulp vitality. Nd: YAG laser has been tested for pulpotomy, resulting in better formation of dentin bridge on the exposed pulp. We also tested Er: YAG laser for endodontic surgery and found that cut dentin surfaces by Er: YAG laser are clean and free of smeared layer. The use of lasers in endodontics is getting popular year by year among Japanese dentists.

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Autofluorescence Diagnosis for Oral Squamous Cell Carcinoma

Mutsuhiko MURAI, Kenji HASHIMOTO, Ichiro YAMADA, Toru HIRANO

1999 Volume 20 Issue 1 Pages 39-46
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_39

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We made spectral analysis in patients with oral SCC using a UV- excited autofluorescence photographic apparatus and found that there were a bimodal peak at 630 and 680nm at the excitation wavelength of 410nm; we found a clear difference from the autofluorescence of the oral cavity of normal human subjects and oral benign diseases. We considered that fluorescence diagnosis of oral SCC would be possible by means of this method.

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Laser Application in Pediatric Dentistry

Keiko YAMADA

1999 Volume 20 Issue 1 Pages 47-53
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_47

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Lots of studies of laser effects on caries prevention as well as inhibition of enamel demineralization have been reported, and clinical applications of laser for those opportunities are most popular in pediatric dentistry. Currently, Er: YAG laser was developed, and it may be useful for cavity preparation of children patiens, because air turbin is much enough to scare them. Suitable lasers for pulp therapy of deciduous tooth or young permanent tooth should be expected.

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Removal of Hard Dental Tissue (cavity preparation) with the Er: YAG Laser and Molecular Vibration Laser

Mamoru KUMAZAKI

1999 Volume 20 Issue 1 Pages 55-61
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_55

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Studies of the light properties of hard tooth tissue established the infrared and Ultraviolet regions the spectrum which are absorbed by dentin (1981, the Japan Society of Conservative Dentistry.)
These studies show that dentin and enamel absorb light in the regions of the spectrum around 3μm and 10μm. Water also absorbs light in the 3μm region.
The Er: YAG laser is effective in the 3μm region and the CO₂ laser in the 10μm region. However, the CO₂ laser has a clinical drawback: it causes heating which cracks the tooth surface. This makes the Er: YAG the best possibility for clinical applications. (1990, The Japan Laser Dental Society.)
It has also been show that the Er: YAG laser removes hard tooth tissue through the micro-explosive reaction of the OOH-Stem of the hydroxy apatite the hydration shell inside the crystal is instantly vaporized.
Our laboratory is getting good results with the clinical application of the Er: YAG laser delivered with a special contact tip developed here. The complete abscess of pain during the procedure is especially noteworthy. This indicate that laser irradiation in the neighbor hood of 10 micron is a significant area of study in terms of conservation dentistry as well as the study of crystalline structures.

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The Surface Modification with FEL Ablation

Seiji OGINO, Kunio AWAZU

1999 Volume 20 Issue 1 Pages 63-67
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_63

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Free Electron Laser (FEL) having the broad tunability and the unique short pulse structure has been developed and used for various applications. Our FEL irradiation experiments show high efficiency for the photo-induced ablation when the laser is tuned to absorption maximum of the target. Using the FEL tuned to phosphoric acid ion (9.4μm) which is an absorption maximum in infrared region on dentine, we investigate the irradiation effect on dentine. The change of property was analyzed by mass spectoscopy and Energy Dispersive X-ray (EDX) spectroscopy. As a result, the atomic ratio of P/Ca had reduced from 0.65 to 0.60. However it had not changed with Er: YAG laser (2.9μm) or CO₂ laser (10.6μm). Furthermore it was observed that irradiated dentine surface which was amorphous changed to the recrystalized structure. These results indicate that 9.4μm-FEL irradiation caused selective ablation of phosphoric acid ion and annealing.

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Laser Endoscopy and I, until Development of ICG Enhanced Diode Laser Therapy

Hiroaki SUZUKI

1999 Volume 20 Issue 1 Pages 69-72
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_69

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We introduced the endoscopic injection sclerothrapy (EIS) and the endoscopic variceal ligation (EVL) to Japan as a less-invasive treatment for esophageal varices. Nowadays these techniques have been widely accepted as the first choice of the treatment. However, its safety and efficacy were not completely achieved yet. On the other hand, the use of endoscopic laser therapy has been limited to cases of acute variceal bleeding because of laser induced bleeding due to vaporization of surface tissue.
We developed ICG enhanced diode laser therapy as a prophylactic therapy for esophageal varices. In the experimental study, we investigated the effect on the esophageal wall from following points of view, it was possible 1. to irradiate waithout vaporization of surface tissue, 2. to coagulate mucosa and sumucosa where varices are located. 3. to protect laser beam from penetrating into muscle layer. Then we applied this technique in 11 cases with esophageal varices, and clinically its safety and efficacy were suggested. In this paper, we refered the process of developement of this new technique through the results of the experimental and clinical study.

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Biomedical Imaging

-including fluorescence endoscopy, infrared endoscopy, three-dimentional endoscopy and color imaging diagnosis using endoscopic spectroscopy system

Hisao TAJIRI

1999 Volume 20 Issue 1 Pages 73-74
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_73

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Clinical and Basic Study of PDD/PDT

Harubumi KATO, Susumu NAKASIMA

1999 Volume 20 Issue 1 Pages 75-76
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_75

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Current Trends of Laser Application in the Cardiovascular Diseases

Masayoshi OKADA

1999 Volume 20 Issue 1 Pages 77-80
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_77

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Laser Ophthalmology

Shigekuni OKISAKA

1999 Volume 20 Issue 1 Pages 81-82
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_81

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Application of Laser on Day Surgery in Otolaryngology and head and neck

Toshio YAMASHITA

1999 Volume 20 Issue 1 Pages 83-84
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_83

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Application of Laser for oral cancer

Kenji HASHIMOTO

1999 Volume 20 Issue 1 Pages 85-86
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_85

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[title in Japanese]

1999 Volume 20 Issue 1 Pages 87-88
Published: 1999
Released on J-STAGE: September 24, 2012

DOIhttps://doi.org/10.2530/jslsm1980.20.1_87

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