Laser irradiation tip, laser irradiation handpiece, laser treatment apparatus, and laser irradiation tip end member

A laser irradiation tip has a main body and a tip end portion. The main body is connected with a handpiece and irradiating therapeutic laser with high absorbability in water. The tip end portion being connected with the main body. The main body of the laser irradiation tip has an optical fiber for guiding the therapeutic laser, a water flow path, and an air flow path in a parallel manner. The tip end portion of the laser irradiation tip has a connection portion with the main body, a water guide path communicated with the water flow path of the main body, an air guide path communicated with the air flow path of the main body, a fiber guide portion capable of inserting a tip side portion of the optical fiber, and a mixing chamber of water and air.

TECHNICAL FIELD

The present invention relates to a laser irradiation tip, a laser irradiation handpiece having the laser irradiation tip, a laser treatment apparatus including the laser irradiation handpiece, and a laser irradiation tip end member constituting the laser irradiation tip. More particularly, the present invention relates to improvement of spray mechanism of a treatment device for irradiating laser during spraying of mixed mist of water and air.

BACKGROUND ART

Recently, a laser treatment apparatus has been widely used in the field of dental examination. The laser treatment apparatus basically comprises a laser generation apparatus, an optical guiding device for guiding laser beam, a handpiece connected with the tip end of the optical guiding device, and a laser irradiation tip mounted on the tip end of the handpiece. The laser generation apparatus of the laser treatment apparatus can use several kinds of laser generation apparatus for generating laser such as Er:YAG laser, carbon dioxide laser, Nd:YAG laser, semiconductor laser. Er:YAG laser with high absorbability in water has been used these days, wherein a spray mechanism is attached for spraying mixed mist of water and air on a laser irradiation region taking advantage of absorbability in water. The laser treatment apparatus having the spray mechanism of mixed mist of water and air is disclosed in Patent Literatures 1 to 4.

Patent Literature 1 discloses a dental treatment apparatus for removing matter from the surface of teeth by pulsed laser in which a liquid layer of 10 to 100 micrometers in thickness is formed on teeth. Patent Literature 2 discloses a laser treatment apparatus which is provided with a handpiece for irradiating Er:YAG laser and sprays mixed fluid of liquid and gas to a patient to be irradiated with laser from a position behind an output end of laser. Patent Literature 3 discloses a laser treatment apparatus which avoids extra laser absorption by setting timing of spraying mixed mist of water and air at the time of irradiating laser pulse. The paragraph [0004] in Patent Literature 4 discloses an optical cutter (laser treatment apparatus) for irradiating Nd:YAG laser on an affected area in which water and air are mixed in a mixing chamber provided around a fiber conduit pipe for laser irradiation and delivered along the conduit pipe via a mesh screen. Patent Literature 4 discloses that a program is provided for adjusting size and speed of liquid particles in such a manner that electromagnetic energy is absorbed by damp air and/or atomized fluid particles to impart disruptive forces to skin (referring toFIG. 5).

Patent Literature 5 discloses an apparatus for removing dental caries by laser having a delivery device for supplying cooling water to an irradiation area with laser, not for spraying mixed mist of water and air.

CITATION LIST

Patent Literature

SUMMARY OF INVENTION

Technical Problem

The dental treatment apparatus disclosed in PTL 1 is designed to enhance cutting efficiency by forming a thin water film on the surface of teeth when pulse laser is irradiated; however, it does not disclose specific methods and configuration for forming the water film.

PTL 2 discloses the hourly supply amount of liquid and gas of the mixed fluid of liquid and gas per minute; however it is unclear whether the mixed fluid is in the form of mist. In fact, there is a worry that mist has a large particle diameter and is absorbed in water before laser reaches an object to be cut.

In PTL 3, irradiation of laser and stop of spray are required to be well timed and such a control is anticipated to be difficult. Irradiation pulse frequency of therapeutic laser is 1 to 30 pps (pulse per second), so that it is extremely difficult to timely stop spraying in accordance with the frequency. In case that they are timed, it is clear that, in view of speed of laser, laser irradiation catches up with spray soon and laser is absorbed in water after all.

In the paragraph [0004] in PTL 4, a mesh screen is provided for the mixing chamber for passing the mixture, thereby increasing the number of members unavoidably. A wall can be provided on the outer side of the chamber of the mesh screen and the mixture of water and air can be sprayed from a narrow discharge port around a fiber conduit pipe. Therefore, there is a fear that the spray direction of the mixture may not be fixed and laser may hardly reach the object to be cut. In addition, a complicated apparatus is required in order to program the size and speed of particles, thereby the apparatus becomes expensive and large scale.

PTL 5 discloses a system for supplying cooling water as mentioned above but not for spraying mixed mist of water and air. Therefore, an apparatus for sucking water supplied to an affected area is required so that operation becomes complicated in addition to increase in size and cost of the apparatus. Specifically in dental examination, while a dentist holds a laser handpiece with his dominant hand, the dentist holds patients' lips with the other hand for obtaining wide eyesight and operative field, or he observes by reflecting an area, which is difficult to be perceived, with a dental mirror in the other hand. When a suction mechanism (a vacuum handpiece) is further required to be handled, he needs help of an assistant for sucking and removing cut objects, secretion, and so on. In addition, the patients further suffer from insertion of a plurality of handpieces in mouth.

The present invention is proposed in view of the above-mentioned problems. The object of the present invention is to provide a laser irradiation tip, a laser irradiation handpiece, a laser treatment apparatus and a laser irradiation tip end member in which mixed mist of water and air is extremely minute, and a thin water film is formed on an object to be cut, thereby achieving more efficient cutting ability.

Solution to Problem

The laser irradiation tip of the present invention has a main body and a tip end portion, the main body being connected with a handpiece and irradiating therapeutic laser with high absorbability in water, and the tip end portion being connected with the main body. The main body of the laser irradiation tip has an optical fiber for guiding the therapeutic laser, a water flow path, and an air flow path in a parallel manner. The tip end portion of the laser irradiation tip has a connection portion with the main body, a water guide path communicated with the water flow path of the main body, an air guide path communicated with the air flow path of the main body, a fiber guide portion capable of inserting a tip side portion of the optical fiber, and a mixing chamber of water and air. The optical fiber is inserted into the fiber guide portion so as to project from a front end surface of the tip end portion of the laser irradiation tip, the mixing chamber of water and air is formed by a concave portion which opens on the front end surface of the tip end portion and dents toward the main body side of the laser irradiation tip, tip end open portions of the water guide path and the air guide path face a bottom of the concave portion, and sectional area of the concave portion is larger than total area of the tip end opening portions. Water from the water guide path and air from the air guide path are mixed in the concave portion, and mixed mist of water and air is sprayed substantially parallel to the therapeutic laser in an irradiation direction of the therapeutic laser from a spray end at an opening of the concave portion.

The main body of the laser irradiation tip of the present invention can be constituted with a curved bar-shaped body. In addition, amount of water flowing in the water guide path can be 1.0 to 20.0 milliliter per minute and amount of air flowing in the air guide path can be 0.5 to 15.0 liter per minute. Depth of the concave portion from the spray end can be 0.5 to 1.5 mm. Furthermore, the tip end portion of the laser irradiation tip can be another member different from the main body of the laser irradiation tip, and the connection portion can be a mounting portion capable of attaching or removing the tip end portion to or from the main body.

The laser irradiation handpiece of the present invention is characterized in that a handpiece body capable of handling with fingers incorporates a laser beam guide path for guiding therapeutic laser with high absorbability in water, a water pipe line, and an air pipe line. The above-mentioned laser irradiation tip is attached to the handpiece body in such a manner that the optical fiber provided for the laser irradiation tip, the water flow path, and the air flow path are connected with the laser beam guide path, the water pipe line, and the air pipe line, respectively.

A laser treatment apparatus of the preset invention comprises a laser oscillator for oscillating therapeutic laser with high absorbability in water, a laser transmitter for transmitting the therapeutic laser, a water delivery circuit, an air delivery circuit, and the above mentioned laser irradiation handpiece. The laser irradiation tip end member of the present invention comprises a mounting portion capable of being attached to or removed from a main body of a laser irradiation tip having an optical fiber for guiding therapeutic laser with high absorbability in water, a water flow path, and an air flow path in a parallel manner. The laser irradiation tip end member further comprises a water guide path communicated with the water flow path, an air guide path communicated with the air flow path, a fiber guide portion capable of inserting a tip side portion of the optical fiber, and a mixing chamber of water and air. The optical fiber is inserted into the fiber guide portion so as to project from a tip end portion thereof, the mixing chamber of water and air is formed by a concave portion which opens on a front end surface of the laser irradiation tip end member and dents toward the main body side, and tip end open portions of the water guide path and the air guide path face a bottom of the concave portion, and sectional area of the concave portion is larger than total area of the tip end open portions. Furthermore, water from the water guide path and air from the air guide path are mixed in the concave portion and mixed mist of water and air is sprayed substantially parallel to the therapeutic laser in an irradiation direction of the therapeutic laser from a spray end at the opening of the concave portion.

Advantageous Effects of Invention

In the laser irradiation tip, the laser irradiation handpiece, the laser treatment apparatus, and the laser irradiation tip end member of the present invention, the laser beam generated by the laser oscillator of the laser treatment apparatus reaches the laser irradiation tip mounted on the main body of the laser irradiation handpiece via the laser transmitter and the light guide path housed in the laser irradiation handpiece. The laser beam reached the laser irradiation tip is transmitted to the optical fiber provided on the main body of the laser irradiation tip, passes through the fiber guide portion at the tip end portion of the laser irradiation tip, and is irradiated on a target object from the tip end of the optical fiber projecting from the front end of the tip end portion of the laser irradiation tip. Water sent from the water delivery circuit of the laser treatment apparatus reaches the laser irradiation tip mounted on the main body of the laser irradiation handpiece via the water pipe line housed in the laser irradiation handpiece. The water reached the laser irradiation tip flows to the mixing chamber of water and air, to be mentioned later, via the water flow path of the main body of the laser irradiation tip and the water guide path at the tip end portion of the laser irradiation tip. Air sent from the air delivery circuit of the laser treatment apparatus reaches the laser irradiation tip mounted on the main body of the laser irradiation handpiece via the air pipe line housed in the laser irradiation handpiece. Air reached the laser irradiation tip flows to the mixing chamber of water and air, to be mentioned later, via the air flow path of the main body of the laser irradiation tip and the air guide path at the tip end portion of the laser irradiation tip.

The mixing chamber of water and air is formed by the concave portion which opens on the front end surface of the tip end portion of the laser irradiation tip (the tip end member) and dents toward the main body side of the laser irradiation tip, the tip openings of the water guide path and the air guide path face the bottom of the concave portion, thereby mixing water and air flowing from each tip opening in the concave portion. The sectional area of the concave portion is designed to be larger than total area of the tip openings, so that fluid pressure values of water and air flowing from the tip openings decrease in the concave portion. As a result, water particles are refined and mixed with air, thereby generating uniform mixed mist of water with minute particles and air (called mixed water/air mist, hereinafter). The mixed water/air mist is sprayed substantially parallel to therapeutic laser in the irradiation direction of the therapeutic laser from the spray end at the opening of the concave portion. Because the mixed water/air mist comprises uniform mist of minute water particles and, in addition, is sprayed substantially parallel to therapeutic laser, laser beam irradiated from the tip end of the optical fiber is avoided to be absorbed in the mist before reaching the object to be irradiated. If the object to be irradiated is an object to be cut, like teeth, cutting efficiency is improved with efficient reduction in laser output. The mixed water/air mist attaches on the surface of the object to be irradiated and forms a thin water film, so that energy of laser can be absorbed and distributed, thereby executing efficient transpiration (cutting). Furthermore, the sprayed mixed water/air mist does not form drops of water on the surface of the object to be irradiated, so that it is not necessary to suck and remove water drop, thereby reducing burden on an operator and pain of patients.

When the main body of the laser irradiation tip is constituted with the curved bar-shaped body, the affected area (teeth) is accessible without hindering eyesight of an operator by the handpiece in case of dental examination wherein handpieces are inserted in a narrow oral cavity.

When amount of water flowing in the water guide path of the main body of the laser irradiation tip is designed to be 1.0 to 20.0 milliliter per minute, amount of air flowing in the air guide path is designed to be 0.5 to 15.0 liter per minute, and depth of the concave portion constituting the mixing chamber is designed to be 0.5 to 1.5 mm from the spray end, most suitable spray condition of mixed water/air mist as mentioned above is able to be obtained. When amount of water is less than 1.0 milliliter per minute and amount of air is less than 0.5 liter per minute, water drops become too large and spray condition of mist is apt to be disturbed or pulsated. On the other hand, when amount of water is larger than 20.0 milliliter per minute and amount of air is larger than 15.0 liter per minute, water and air are not appropriately mixed, spray condition of mist is apt to be disturbed, the spray direction of the mist does not become substantially parallel to the therapeutic laser beam, and the spray direction is apt to incline. When depth of the concave portion is less than 0.5 mm, water and air are not well mixed. When the depth of the concave portion is larger than 1.5 mm, water and air are not appropriately mixed, water drops are apt to become larger, the spray condition of the mist does not become substantially parallel to the therapeutic laser beam and the spray direction is apt to incline.

When the tip end portion of the laser irradiation tip is another member different from the main body of the laser irradiation tip, and the connection portion is the mounting portion capable of attaching or removing the tip end portion to or from the main body, the above-mentioned spray function of mixed water/air mist is able to be attached later to an existing laser irradiation tip which is not capable of spraying the mixed water/air mist and the laser irradiation tip is able to be preferably applied in many examinations. When various kinds of laser tips are prepared, such as laser tips having concave portions of different size (sectional area, depth and so on) and the laser tips being different in diameter of the tip end openings of the water guide paths and air guide paths, laser treatment can be executed while spraying mixed water/air mist appropriate for the above-mentioned examination by choosing one of the above-mentioned laser tips. In addition, an operator has freedom for selection of handpiece and treatment methods.

DESCRIPTION OF EMBODIMENTS

Embodiments of the laser irradiation tip, the laser irradiation handpiece having the laser irradiation tip, the laser treatment apparatus, and the laser irradiation tip end member of the present invention are explained based on the drawings. A laser treatment apparatus1shown inFIG. 1is a dental laser treatment apparatus in which a laser oscillator11oscillating laser with high absorbability in water, a water delivery circuit12supplying water (sometimes including normal saline) and an air delivery circuit13supplying air (sometimes including inert gas) are provided in a laser apparatus body10with casters. Laser generated by the laser oscillator11is transmitted to a dental laser irradiation handpiece2, to be mentioned later, via a laser transmitter11a. The laser treatment apparatus1has a flexible hose3feeding laser beam from the laser oscillator11, water from the water delivery circuit12and air from the air delivery circuit13, which are supplied by the apparatus body10, to the dental laser irradiation handpiece2outside the apparatus body10, a setting/operating portion14and a display15provided on the upper front face of the apparatus body10, and a foot controller16connected with the laser apparatus body10. The flexible hose3includes bundles of a laser beam guide body11bconnected with the laser transmitter11aof the laser oscillator11, a water supply tube12aconnected with the water delivery circuit12, and an air supply tube13aconnected with the air delivery circuit13and is connected with a base portion of the dental laser irradiation handpiece2. The setting/operating portion14comprises an operation key, a touch panel, a rotary knob and the like in such a manner that irradiation conditions of laser beam, spray amount of water or air, existence of spraying, and the like are able to be set or operated. The display15comprises a liquid crystal panel (LCD) and the like and displays the set irradiation conditions and the like. The foot controller16is a switch for operating irradiation of laser beam or for operating supply of water or air and is operated with an operator's foot. Furthermore, the laser apparatus body10includes a cooling device for the laser oscillator attached to the laser oscillator11and an electric supply (they are not shown in the figure).

The water delivery circuit12has a tank for containing water such as purified water or normal saline and supplies water to the water supply tube12aby means of a pump mechanism. The air delivery circuit13is designed to generate compressed air or compressed inert gas to be supplied to the air supply tube13a. A blower or a compressor is used for generating air, and a gas cylinder filled with compressed inert gas is used for generating inert gas.

Laser generated by the laser oscillator11is therapeutic laser with high absorbability in water such as Er-YAG laser, Co2laser, Er.Cr:YSGG laser, and Ho:YAG laser. Laser beam generated by the laser oscillator11is guided to the dental laser irradiation handpiece2via the laser transmitter11aand the light guide body11b. The light guide body11bcan be a solid or hollow optical fiber (waveguide) housed in the flexible hose3. Manipulator-type transmitter (multiple joint transmitter) can be used other than the flexible hose3.

The dental laser irradiation handpiece2of the embodiment of the present invention comprises a connection base portion20A connecting with the flexible hose3, a grip portion (a barrel portion)20B connected with the connection base portion20A to be grasped and handled by an operator's hands, a handpiece main body20including a head portion20C extending from the tip side of the grip portion20B, and a dental laser irradiation tip4to be detachably mounted on the head portion20C. A connection portion of the flexible hose3and the connection base portion20A of the handpiece body20is constituted with a detachable connector portion. In such connection, the laser beam guide body11b, the water supply tube12aand the air supply tube13ain the flexible hose3are connected with base end portions of a laser beam guide path21, a water pipe line22, and an air pipe line23, to be mentioned later, respectively, in the handpiece body20. As a result, the laser beam guide body11bin the flexible hose3is optically connected with the laser beam guide path21in the handpiece body20, the water supply tube12ain the flexible tube3is water-tightly connected with the water pipe line22in the handpiece body20, and the air supply tube13ain the flexible hose3is air-tightly connected with the air pipe line23in the handpiece body20.

The connection portion of the handpiece body20and the dental laser irradiation tip4is explained in detail referring toFIG. 2andFIG. 3. As shown inFIG. 2, the handpiece body20has a cylindrical main tube20aextending from the grip portion20B to the head portion20C and an exterior sleeve portion20bexternally fitted on the cylindrical main tube20a. The laser beam guide path21is constituted with a hollow or solid waveguide (optical fiber) and is concentrically provided in the handpiece body20along the longitudinal direction. The tip end portion of the laser beam guide path21is held with a ferrule24as far as the inside of the head portion20C. The ferrule24is inserted into a support ring24aconcentrically fitted in the main tube20ato be supported, the tip end of a fixing threaded member24bscrewed to the support ring24ais aligned with a circumferential groove24cformed around the ferrule24, thereby positioning the ferrule24to be fixed relative to the support ring24a. The support ring24ais positioned at a predetermined position in the main tube20ato be internally fitted and supported via a spacer collar member20dby means of a tubular holder member20cscrewed in the tip end portion of the main tube20a. A tip end21aof the laser beam guide path21inserted to the ferrule24to be supported faces an optical collecting lens (drum lens)25held by the holder member20c.

The water pipe line22and the air pipe line23are formed with a narrow tube; the tip end portions are held by the holder member20cand are communicated with a water communication pipe line22aand an air communication pipe line23aprovided for the holder member20c, respectively. A tip holder26is fitted to the holder member20cand is fixed and held in a fitted condition when a hexagon cap nut27is screwed to a tip end portion of the exterior sleeve portion20b. The tip holder26is a hollow tubular body and a concentrically formed inner tubular portion26ais a joint portion for detachably screwing a tip main body5constituting the dental laser irradiation tip4to be mentioned later. A water communication line22band an air communication line23bare formed on a tube wall of the tip holder26. When the tip holder26is fitted and fixed to the holder member20c, the water communication line22band the air communication line23bare connected with the water communication pipe line22aand the air communication pipe line23avia the circumferential grooves formed on the periphery of the tip holder26, respectively. The tip end portions of the communication lines22b,23bare opened toward the inner tubular portion26aof the tip holder26. Female threaded portion26bfor screwing and connecting with the tip main body5is formed on the inner tubular portion26aof the tip holder26.

InFIG. 2, the water pipe line22and the air pipe line23, the water communication pipe line22aand the air communication pipe line23a, the water communication line22band the air communication line23b, the fixing threaded member24band so on are shown on the same section for convenience; however, they should be formed at appropriate places in the circumferential direction in view of design in such a manner that they do not interfere each other. The air communication pipe line23amay be designed to be diverged for introducing cooling air around the optical collecting lens25and the tip end21aof the laser beam guide path21in order to cool down the vicinity therearound and to remove foreign matters attached on the tip end21aof the laser beam guide path21, an incidence plane and an output plane of the optical collecting lens25, or a base end surface55aof the optical fiber55to be mentioned later. If the laser beam guide path21in the handpiece body20is hollow, the optical collecting lens25is able to be cooled down or foreign matters in the optical fiber55are able to be removed by introducing air in the laser beam guide path21.

A plug portion51in the form of bamboo shoot, multistep like portion, to be screwed and connected with the inner tubular portion26aof the tip holder26and a knurled rotary knob52for screwing the plug portion51are integrally formed at a connection portion of the main body5with the head portion20C of the handpiece main body20. A male threaded portion51ato be screwed to the female threaded portion26bis provided on the circumference of the plug portion51and a milled surface51bis formed on a part of the male threaded portion51a. A gap is formed between the male threaded portion51aand the female threaded portion26b, which are screwed together, by providing the milled surface51band is provided with an air inlet51c. When the plug portion51is screwed and connected with the tip holder26, the air inlet51cis designed to be aligned with the air communication line23band to be communicated with an air flow path54(referring toFIG. 5) in an exterior pipe50, to be mentioned later, via the plug portion51. A water inlet51dis formed at a region of the circumference of the plug portion51in the axially opposite direction to the air inlet51c. When the plug portion51is screwed and connected with the tip holder26, the water inlet51dis designed to be aligned with the water communication line22band to be communicated with a water flow path53(referring toFIG. 5) to be mentioned later, in the exterior pipe50via the plug portion51. Three O-rings51e. . . (referring toFIG. 2) for isolating air communication regions and water communication regions are provided for the circumference of the plug portion51via O-ring grooves51f. . . (referring toFIG. 3) in such a manner that air communication via the air inlet51cbecomes air-tight and water communication via the water inlet51dbecomes water-tight. The base end surface55aof the optical fiber55faces a light emitting surface of the collecting lens25to execute optical connection of laser beam via the collecting lens25.

The laser irradiation tip4of the embodiment of the present invention is explained in detail referring toFIG. 4andFIG. 5. The laser irradiation tip4comprises the tip main body5made of a curved bar-shaped body and a laser irradiation tip end member (the tip end portion of the tip)6detachably mounted on a tip end portion of the main body5. The tip main body5has the curved exterior pipe50, an intermediate pipe50acoaxially provided in the exterior pipe50, and an inner pipe50bcoaxially provided in the intermediate pipe50a. The tip side of the pipe50aextends so as to project from a tip end of the intermediate pipe50aand a tip side of the inner pipe50bextends so as to project from a tip end of the intermediate pipe50a. The plug portion51and the knurled rotary knob52are integrally formed with the exterior pipe50. An annular gap between the exterior pipe50and the intermediate pipe50aconstitutes the air flow path54, an annular gap between the intermediate pipe50aand the inner pipe50bconstitutes the water flow path53, and an inner tubular portion of the inner pipe50bconstitutes a fiber guide portion56. The optical fiber55, the water flow path53and the air flow path54, which are inserted into the fiber guide portion56, are coaxially formed and are provided substantially in parallel with the tip main body5. The plug portion51and the knurled rotary knob52of the tip main body5are integrally formed with metal (stainless steel, nickel-plated brass or the like) or resin. The exterior pipe50is made of metal (stainless steel, brass or the like), ceramics, resin or the like and has an outside diameter of 1.0 to 3.0 mm. The material and dimension are optionally selected and designed in view of material and dimension of surrounding members and necessity of sterilization at high temperature. In view of application to a tip mounted to a contra-type handpiece, the outside diameter of the external pipe50is able to be larger than 3.0 mm.

The laser irradiation tip end member (the tip end portion of the laser irradiation tip)6is detachably mounted on the tip end portion of the tip main body5. The laser irradiation tip end member6in the figures, which is hollow and in the form of an approximate cylinder, is formed with a molded body60made of resin or the like and has a mounting portion (connection portion)61detachable to the exterior pipe50of the tip main body5by external press-fit. An inner tubular portion of the molded body60comprises a large-diameter inner tubular portion60aof which inside diameter is approximately equal to or a little smaller than the outside diameter of the exterior pipe50, a middle-diameter inner tubular portion60bof which inside diameter is approximately equal to the outside diameter of the intermediate pipe50a, and a small-diameter inner tubular portion60cof which inside diameter is approximately equal to the outside diameter of the inner pipe50. The large-diameter inner tubular portion60a, the middle-diameter inner tubular portion60band the small-diameter tubular portion60care formed in concentric with an axial center Lo of the molded body60and in a stepped manner from the mounting portion61to a front end surface62. When the laser irradiation tip end member6is mounted on the tip main body5, the large-diameter inner tubular portion60ais fitted under pressure onto the exterior pipe50, the middle-diameter inner tubular portion60bis air-tightly fitted onto the intermediate pipe50a, and the small-diameter inner tubular portion60cis water-tightly fitted onto the inner pipe50b. A part of the molded body60corresponding to the large-diameter inner tubular portion60asubstantially constitutes the mounting portion61.

When the laser irradiation tip end member6is mounted on the tip main body5, the inner pipe50bof the tip main body5is fitted to the small-diameter inner tubular portion60c, and extends so as to penetrate the laser irradiation tip end member6, namely the molded body60, along the axial center Lo and to project out of the front end surface62. The fiber guide portion56formed by the inner tubular portion of the inner pipe50breaches the laser irradiation tip end member6and also constitutes the fiber guide portion of the laser irradiation tip end member6. The optical fiber55to be inserted in the fiber guide portion56further projects from the tip end of the fiber guide portion56. An exterior body, called a jacket, of a projecting portion of the optical fiber55is removed so as to expose a core material55bmade of a core and a clad, or solely of a core, and the optical fiber55is concentrically held with the laser irradiation tip end member6. The tip end surface55cof the core material55bconstitutes an output end of laser beam.

A stepped portion of the small-diameter inner tubular portion60cand the middle-diameter inner tubular portion60bof the molded body60is formed with a water pocket63acommunicated with the water flow path53and a water guide path63is formed in parallel with the axial center Lo from the water pocket63ato the front end surface62. A stepped portion of the middle-diameter inner tubular portion60band the large-diameter inner tubular portion60ais formed with an air pocket64acommunicated with the air flow path54and an air guide path64extending in parallel with the axial center Lo from the air pocket64ato the front end surface62is formed in the proximity of the water guide path63. The molded body60has a concave portion65which opens on the front end surface62and dents toward the tip main body5. Tip end open portions63b,64bof the water guide path63and the air guide path64face a bottom portion65aof the concave portion65. The open portion of the concave portion65constitutes a spray end65b, to be mentioned later, of mixed water/air mist, and depth “D” of the concave portion65from the spray end65bis 0.5 to 1.5 mm. Such the concave portion65constitutes a mixing chamber of water and air (allotted with numeral65, hereinafter). If the depth “D” becomes larger than 1.5 mm by increasing air pressure, it is possible to spray appropriate mist although there causes a little disturbance.

The sectional area of the concave portion65(dimension of surface area orthogonal to the axial center Lo) is designed to be larger than the total dimension of the tip end open portions63b,64bof the water guide path63and the air guide path64. Specifically, dimension of the tip end open portion63bof the water guide path63is designed to be 0.0079 to 3.14 square millimeter (0.1 to 2 mm in diameter) and dimension of the tip end open portion64bof the air guide path64is designed to be 0.0079 to 3.14 square millimeter (0.1 to 2 mm in diameter). In the figure, dimension of the tip end open portion63bof the water guide path63is larger than dimension of the tip end open portion64bof the air guide path64; however, they can be same or vice-versa. The open dimension of the spray end65b(sectional area of the concave portion65) is designed to be 0.35 to 20 square millimeter.

How to cut and remove caries and so on of teeth using the above-mentioned dental laser treatment apparatus1is briefly explained. The water delivery circuit12and the air delivery circuit13are controlled by the setting/operating portion14of the laser apparatus body10in such a manner that water amount flowing in the water guide path63becomes 1.0 to 20.0 milliliter per minute and air amount flowing in the air guide path64becomes 0.5 to 15.0 litter per minute. Laser output of the laser oscillator11is controlled to cut and remove appropriately. An operator grasps the grip portion20B of the laser irradiation handpiece2with his hand, inserts the laser irradiation tip4to a patient's oral cavity (not shown), and puts the tip end surface55cof the optical fiber55close to the surface of a tooth to be treated (not shown). The tip main body5of the laser irradiation tip4is formed with a curved slim bar-shaped body, so that the operator's eyesight is not obstructed and the objective tooth is easily accessed. The operator operates the foot controller16with his foot or presses several switches (not shown) provided for the laser irradiation handpiece2with his finger, and irradiates laser beam from the output end to an objective tooth. Simultaneously, the water delivery circuit12and the air delivery circuit13are driven to flow water and air to the water-air mixing chamber65through the water guide path63and the air guide path64, water and air are mixed in the mixing chamber65, then the mixed water/air mist is sprayed in parallel with the irradiation direction of laser light.

The sectional area of the water-air mixing chamber (concave portion)65is designed to be larger than the total area of open dimension of the tip end open portions63b,64b, so that flow pressure values of water and air flown in the water-air mixing chamber65are reduced and water is refined by the action of air while passing through the mixing chamber65, thereby generating uniformly mixed water/air mist of minute water particles. The mixed water/air mist is sprayed from the spray end65bin a spray pattern “we” shown inFIG. 3. The spray pattern “we” comprises uniform mist of minute water particles and is approximately parallel with an irradiation pattern “L” of laser beam irradiated from the tip end surface55cof the optical fiber55, thereby avoiding absorption of laser beam in the mixed water/air mist before the laser beam reaches the objective tooth. As a result, cutting efficiency is improved and laser output is efficiently reduced.

FIG. 6is a graph of validation results showing relation of cutting amount by laser irradiation and distance (tip end distance) between the tip end of the tip and the surface of the body to be irradiated when laser is irradiated while spraying mixed water/air mist to a pseudo tooth (object to be irradiated). The outlined bar graph shows the case when a conventional laser irradiation tip without having the mixing chamber of water and air of the present invention is used and the dotted bar graph shows the case when the laser irradiation tip of the present invention is used. In both cases, laser type, laser output, and flow amount of water or air are the same, the tip end distance is changed to 0.5 mm, 1.0 mm, and 2.0 mm, and cutting amount in volume is measured after being irradiated for the predetermined time. Measurement is executed five times per tip end distance and the average value is shown.

It is found inFIG. 6that cutting ability of the laser irradiation tip of the present invention is improved by 1.2 times, compared with the conventional tip at the distance of 0.5 mm and 1.0 mm from the tip end of the tip to the object to be irradiated. It means that laser is avoided from being absorbed in the mixed water/air mist before reaching the object to be irradiated. In the validation test, it is found that mixed water/air mist adheres to the surface of the object to be irradiated and forms a thin water layer when the laser irradiation tip of the present invention is used. It is confirmed that such validation results support the laser energy is absorbed and distributed, and efficient evaporation (cutting) is executed. In addition, sprayed mixed water/air mist does not form a water drop on the surface of the object to be irradiated, so that it is not necessary to suck and remove the water drop.

In the above-mentioned embodiment, the dental laser irradiation apparatus is exemplified; however, the present invention is not limited to such an apparatus, and the present invention is able to be used for other laser treatment apparatus. One water-air mixing chamber65is used for the laser irradiation tip4in the embodiment; however, a plurality of mixing chambers can be provided around the axial center Lo of the optical fiber. The shape of the water-air mixing chamber65(shape seen from the direction of the arrow “B” inFIG. 2) is not limited to that shown in the figure; it can be circular, rectangular, oval or the like. The laser irradiation tip end member6is detachably mounted to the tip main body5by compression; however, it can be mounted with a screw. The laser irradiation tip end member6detachably inserted by compression is advantageous for applying to an existing laser irradiation tip. Furthermore, in place of the detachable laser irradiation tip end member6, a part of the laser irradiation tip can be constituted in such a manner that the tip end portion of the tip is adhered to be integrated by adhesive agent to the exterior pipe50constituting the tip main body5or is integrally formed with the exterior pipe50.

REFERENCE SIGNS LIST