Vaccination is the most effective strategy for prevention of infectious diseases. The health of the human race has been enormously benefited from vaccination, and various vaccines have effectively saved a lot of lives from morbidity and mortality to date. However, development of new vaccines is increasingly facing challenges to meet growing threat from not only existing infectious diseases but also emerging / re-emerging infectious diseases due to global expansion of tourism and human migration. Generally, modern vaccines are safer, but they tend to be highly targeted and less immunogenic on their own. As a result, they often require an immunogenic adjuvant to enhance immune responses and achieve clinical significance. However, many licensed and candidate chemical or biological adjuvant have been linked to side effects, posing safety concern. A new approach, namely laser-based physical adjuvant, may represent alternative strategy to conventional vaccine adjuvant. Historically, Russian military scientists have put an effort to developing vaccine adjuvant using laser light from 1970’s. Subsequently, US scientists including us reproduced their results and further expanded investigation of use of laser to augment the immune response.

In this short review, we cover our recent progress on development of small handheld laser devices for adjuvanting intradermal influenza vaccines.

In Japan, studies on the development of a practical model of the carbon dioxide laser scalpel started to remove highly hemorrhagic brain tumors bloodlessly. The excellent biomedical characteristics of the carbon dioxide laser enable the surgeon to perform bloodless removal of the tumors. The first clinically applicable carbon dioxide laser scalpel in Japan, MEDILASER-S MODEL MEL 442 was completed in 1975 by improving all the drawbacks of the former test model and manufacturing approval was granted by the Ministry of Health and Welfare on April 22, 1980.

Hollow optical fibers have a tube structure in contrast to common glass-optical fibers made of glass wire and light propagates in the hollow core. Therefore, the hollow optical fiber can transmit mid-infrared light including CO₂ laser light that cannot be delivered by common glass fibers because of the glass absorption. Hollow optical fibers are usually based on glass capillary and a metal film and a polymer film that is transparent in the mid-infrared are formed on the inside of the capillary. The polymer film enhances reflection at a targeted wavelength region by optical interference effect and this reduces the transmission loss of the fiber. A common silver plating is usually used for metal film deposition and a polymer solution is injected into the capillary and dried to from a polymer film. Fabricated hollow optical fibers for CO₂ laser light with an inner diameter of 0.7 mm and a length of 1 m show transmission higher than 90% when the fiber is straight. When bending the fiber, although the transmission is lowered, the fiber keeps transmission high enough for clinical applications.

Clinical carbon dioxide laser devices are classified into gas laser, infrared laser, high power laser, continuous and pulse laser and class 4 laser in safety standard levels. Furthermore, carbon dioxide laser have been classified according to the mode of irradiation, clinical medicine and the presence or absence of recognition by the Ministry of Health, Labour and Welfare. The twelve devices are introduced in this paper.

Due to the evaluation of the CO₂ laser, its usage is becoming more frequent among eye clinics. In these eye clinics, the CO₂ laser is mainly used in external eye surgery such as blepharoptosis, blepharoentropion, and the excision of skin tumors around the eye lid. It is not generally used in internal eye operations, such as cataract or glaucoma surgery.

Any accidental exposure of the cornea to the laser may cause strong astigmatism. However, by protecting the cornea with a cornea protection shield and paying close attention, CO₂ lasers may now be used on conjunctivochalasis and conjunctival tumors.

This article will explain the instances in which CO₂ lasers are used in eye clinics by introducing some preoperative, intraoperative and postoperative cases. Through use of the CO₂ laser, bleeding is reduced, and surgery time is dramatically shorter than surgery using scalpel and bipolar technique. It seems likely that the use of the CO₂ laser will spread rapidly across eye clinics.

Laser treatment is now used not only in Otorhinolaryngology and Head and Neck surgery but other medical departments. In this paper, I explained about the laser treatment in Otorhinolaryngology and Head and Neck surgery according to the kind of diseases, such as secretory otitis media, otosclerosis, allergic rhinitis and superficial carcinoma of the pharynx and larynx. I hope it may be easy to understand the contents for every specialist in other medical departments.

CO₂ laser vaporization has been reported to be useful for the treatment of portio erosion, condyloma acuminata, carcinoma in situ of the uterine cervix and Bartholin's glands cyst. Since complication of CO₂ laser vaporization is slight, this treatment has become general treatment. We report here the treatment using CO₂ laser vaporization for the cervical dysplasia including our experience.

Recently, percutaneous coronary intervention and coronary artery bypass grafting are carried out for ischemic myocardial diseases. However, there are some cases which these methods are not carried out, because coronary artery are too small and narrow. For those patients, we have created new channels in the ischemic myocardium by CO₂ laser. Fourtunately, newly created myocardial channels have widely opened in long-term period. So, 1^st clinical operation was done on 12. November 1985. This was the case that 1^st clinical successful case were carried out in the world by transmyocardial laser revascularization.

And then, much attention has to paid to maintain the long-term patency after vascular anastomosis especially for the small-caliber vessels. So, we have arranged some ideas for them with small amount of suture materials. That is, low energy CO₂ laser was utilized to make vascular anastomosis with a few stay sutures. Laser power was 20-40 mW, irradiation time was 6-12 sec/mm.

Currently,the carbon dioxide gas laser approved in the dental field is only at the wavelength of 10,600 nm. The application to the actual oral cavity condition can be applied to the actual oral pathology by abscess incision, chronic periodontal inflammation, evaporation for aesthetic improvement of pigmented gingiva, frenectomy, tumor resection, secondary surgery after implantation of dental implant, gingival fenestration of difficulty eruptive tooth, application to stomatitis, gingivectomy, evaporation of defective granulation tissue, evaporation of inflammatory edematous gingival hyperplasia tissue, treatment for hypersensitivity of teeth. Some of them are introduced.

In recent years, due to advances in technology, laser apparatuses which are small and excellent in operability have been developed, and it became popular also in general animal hospitals. In addition, importance was attached to the idea of quality of life and minimally invasive treatment. Therefore, carbon dioxide laser surgery with less excessive bleeding and less thermal response has become mainstream. In this article, I explain carbon dioxide laser in the veterinary field with a case of onychectomy.

Carbon dioxide laser allows the excellent performance of tissue incision, minimal thermal denaturation of and bleeding from an excised area, and rapid wound healing. Therefore, carbon dioxide laser devices are widely used in dermatology and plastic surgery to treat such skin tumors as seborrheic keratosis, soft fibroma, and pigmented nevus. In addition to single pulse, repeat pulse, and continuous wave laser modes, some of the devices even feature super pulse, ultra-pulse, and a scanner. They allow surgeons to choose precise power output, pulse length, and exposure size for treatment. Such versatile devices that enable the selection of modes catering for individual patients are of great benefit to dermatology and plastic surgery.

Since 2004, the fractional laser devices have been introduced and the non-ablative and ablative fractional laser resurfacing have been essential therapeutic techniques in the field of dermatology and plastic surgery. Especially, fractional carbon dioxide laser devices are utilized for the treatment of scars and photo-aged skin. In this manuscript, we introduce the topics of fractional carbon dioxide laser resurfacing concerning about the specifications of fractional laser devices, clinical indications, therapeutic techniques and complications.

As Japanese population is aging, the importance of non-invasive and non-surgical periodontal treatment is increasing because elder people suffering from some systemic diseases and taking many medicines.

The aim of periodontal treatment is to eliminate the biofilm in the periodontal pocket which is major etiologic factor of periodontal disease. A disadvantage of conventional non-surgical periodontal treatment using scaler is that accessibility of scaler to the bottom of pocket is not enough. Accessibility of the laser fiber is better than scaler, so the effect of biofilm removal is expected.

However, as a point of consider, there is a problem of heat of generation.

We discuss, here, the point of advantage of laser treatment rather than conventional methods and of a consideration for usage of laser.

The Nd:YAG laser wavelength is in the near-infrared region of 1,064 nm and shows negligible water absorption. The Nd:YAG laser has different effects on the irradiated tissue depending on the radiation output and conditions such as time and distance. Therefore, we describe the biological effects on cells constituting periodontal tissue by Nd:YAG laser irradiation with some academic papers.

The diode laser frequently used in the field of dentistry has a wavelength of 810 nm. Its wavelength characteristic is not affected by water and it is absorbed by dark colored substances resulting in thermal effects. When human tissue is irradiated, theoretically the Diode Laser just penetrates the surface and reaches inside. However, in addition to that phenomenon, the tip itself emits high thermal energy due to continuous diffuse reflection. Therefore, when the fiber comes into contact with the tissue, the heat of the tip is first transmitted to the tissue before the laser is absorbed by the tissue and heat is generated, and incision and transpiration develop. The system is small, lightweight, power-saving, and is generally delivered by quartz fiber. It is frequently used for soft tissue incisions and is especially excellent for fine gingival contour modifications. With its low power output; healing promotion and pain relieving effects are achieved. In this article we discuss the current state and potential of Diode Laser use in periodontal disease management.

Recently, periodontitis has been received considerably much attention for its association with systemic diseases. This could be attributed to low grade chronic local infection of periodontal tissue following transient bacteremia. Bacteremia could also occur after dental procedures including periodontal treatment, therefore, to prevent and minimize the occurrence of bacteremia, prophylactic administrations of the antibiotics have been tried, but it could not prevent it perfectly. And repeated usage of antibiotic could also cause side effects such as bacterial resistance and microbial substitution. Er:YAG laser could serve for periodontal treatment in both soft and hard tissues for its specific high water absorption capacity. In the present paper, the application of Er:YAG laser for periodontal treatment and its possibility for novel prophylactic method against transient bacteremia are discussed.

Recently, lasers are being increasingly used in periodontal therapy. Among various lasers, the Er:YAG laser is the most suitable for periodontal treatment because this laser enables effective ablation of periodontal hard and soft tissues with minimal thermal side-effects and thereby does not impair wound healing. A number of clinical studies have applied this laser for periodontal pocket treatment and some reported positive results; however, we have not reached a consensus regarding their effects due to differences in the method and parameters of laser irradiation for pocket therapy. In this article, we review the findings of previous clinical studies and introduce a new treatment procedure using Er:YAG laser combined with conventional pocket treatment.

Currently, one of the most unpredictable regenerative treatment in periodontics is class 3 furcations. Dental endoscopes have enabled direct vision and treatment in the furcation areas without the use of dental mirrors. The combination of dental endoscopes and Er:YAG lasers allow root conditioning and preservation of healthy cementum that can lead to predictable periodontal regeneration. This presentation shows successful treatment outcomes for class 3 furcations utilizing this regenerative technique.

A CO₂ laser with a 10.6 μm wavelength is a type of tissue-surface-absorbed laser, that has excellent characteristics for dental medical application. A CO₂ laser with direct irradiation is disadvantageous to apply to periodontal treatment in scaling or vaporizing hard tissue (tooth, bone); however, the far-infrared radiation causes the proliferation of exogeneous cell and capillary growth factors, activates the fibroblast cells, increases the produce of collagen, and promotes wound healing. It is therefore expected that application of a CO₂ laser to the periodontal treatment would promote the reduction of inflammation, painrelief, wound healing, and tissue regeneration. The application to periodontal treatment with a high power CO₂ laser was approved by the Ministry of Health, Labour and Welfare, and the validity of CO₂ laser applications are discussed.