FR2789294A1 - Photo activation device of photosensitive composite materials used in dentistry has optic fibers associated with light emitting diodes in way that surface of diode is optically coupled with inlet surface of one or several optic fibers - Google Patents

Abstract

A light concentration device (23') permits to combine in a point a light emitted from all emitting surfaces (25) of diodes (20). The device (23') includes optic fibers (23) associated with the light emitting diodes (20) in a way that the surface (25) of the diode (20) is adjusted optically with the inlet surface of one or several optic fibers (23).

Description

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  The present invention relates to a device for the photo activation of photosensitive composite materials used in particular in the

dental field.

  In the dental field, composite materials consist of a photopolymerizable resin which reacts to light by modifying its molecular layers or by thermal transformation of its molecules. These two phenomena, which can be combined, are dependent on the wavelength of the radiation emitted but also on the absorption capacity of the composite material and have the effect of activating its photo initiators and obtaining a body with mechanical properties. and aesthetics defined according to

dental application.

  Photopolymerization devices generally consist of a housing containing an emitting source controlled by an electronic circuit which includes a timer making it possible to optimize the exposure time so as to minimize the heating of the tissues surrounding the area to be treated. Furthermore, to be sure of covering the spectral range of photosensitivity of the material used and to provide sufficient energy for the reaction, these devices use lamps, the emission spectrum of which is very

  large, in combination with filters.

  Among the various light sources, mercury vapor lamps have been used, but these emit too much ultraviolet radiation, dangerous for

the patient's eyes.

  To avoid this drawback, these lamps have been replaced by halogen lamps. However, these lamps whose lumen / watt ratio is low require exposure of the area to be treated for a long period of time, forcing the patient to keep his mouth open for a long time. On the other hand this overexposure is accompanied by a heating of the lamp which requires the use

  noisy and bulky cooling systems.

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  To overcome these drawbacks, plasma arc lamps are currently used with better lumen / watt efficiency and part of the spectrum between 430 and 490.m is used, which significantly increases the energy delivered and provides the power required for rapid polymerization. However, this increase in power is accompanied by a large increase in the heat given off. In the devices known to date on the one hand the conversion of electrical energy into light energy is poor, and on the other hand the cooling systems are complex and noisy, which

increases the cost of the device.

  The object of the present invention is to remedy these drawbacks by proposing an apparatus for photopolymerization of composite materials and of products for whitening teeth, making it possible to carry out a gradual photopolymerization of the different layers of the material to be treated while allowing time to be preserved. low exposure and reduce so

significant heat released.

  The light-curing apparatus according to the invention comprises a housing containing an electric power supply unit electrically controlled by an electronic central unit and a light source connected to said power supply characterized in that the light source consists on the one hand of '' a plurality of light diodes each associated with one or more optical fibers, which optical fibers are intended to collect the light emitted by said diodes and are joined together and maintained so as to obtain at the exit of the network of optical fibers the emission surface as small as possible, said light emission being guided by an optical guide, connected to the outlet of said optical fibers, on the surface to be treated and in that the coupling between a diode and one or more of said optical fibers is carried out by

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  optimally adjusting the emitting surface of the diode with the corresponding optical fiber or fibers so as to collect the maximum of the active part of the light emission from each diode in the corresponding fiber or fibers. Thus, the spectral distribution of the light emission guided over the area to be treated and which is determined by the spectral and energy characteristics of the light emissions of the diodes can be modified by cutting off or not the supply of the diodes emitting in a given spectrum and / or by controlling the current supply of the diodes so as to vary their emission power and therefore their

optical characteristics.

  The light-emitting diodes can be diodes

  light emitting or laser diodes.

  The input of each fiber is located either opposite and in the immediate vicinity of the emissive surface of the corresponding diode, or opposite and in the immediate vicinity of an optical imaging device arranged

  in front of the emissive surface of said diode.

  In a preferred embodiment of the invention, the diodes are regularly arranged on a plate and the optical fibers are each inserted into a hole with a diameter slightly greater than the diameter of said fibers and formed in a plate positioned by centering means near the diode support plate and whose hole pitch is equal to

that of said diodes.

  According to an additional characteristic of the invention, the control of the power supply of the light-emitting diodes can be carried out manually by means of adjustment knobs or automatically by means of the central unit containing in its memory the parameters inherent in the control of said diodes allowing

  to obtain different energy profiles.

  According to another additional characteristic of the invention, the electrical supply of the diodes is

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  adjustable in pulsed mode so as to obtain higher instantaneous powers, favorable for

  special polymerization applications.

  According to another additional characteristic of the invention, the light resultant at the outlet of the optical fiber bundle comprises at least two wavelengths preferably situated respectively around 380 or 475pm and 750gm, so as to obtain both the radiation necessary for certain composite materials and suitable radiation for thermal action on products intended for bleaching

teeth.

  According to another additional characteristic of the invention, the core of the optical guide in which the light resultant propagates at the outlet of the bundle of optical fibers can be made of plastic,

glass, or be liquid.

  The advantages and features of the present invention will become more apparent from the

  description which follows and which relates to the appended drawing,

  which represents several non-limiting embodiments. - Figure 1 shows the block diagram

of the device according to the invention.

  - Figure 2a shows a perspective view of the light source consisting of a multiplicity of light emitting diodes each associated with a

optical fiber.

  - Figure 2b shows a detailed view of the

  coupling of a diode with an optical fiber.

  FIG. 3a represents the emission spectrum of four light-emitting diodes of

  different spectral components.

  - Figure 3b shows the overall spectrum resulting from the addition of emissions

  of the four previous diodes.

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  Referring to FIG. 1, it can be seen that an apparatus intended for the photopolymerization of composite materials and for the photoactivation of products intended for teeth whitening consists of a housing 1 housing an electronic central unit 10 electrically connected to a power supply unit 11 of a light source 2 generating light intended to be applied by means of a waveguide 12 ending in a bent end piece 12 ′, on an area to be treated, not

represented.

  The central unit 10 is also electrically connected to an interface 13 comprising control keys 14 and 14 ′ and control lights 15 allowing the operator to interact with the device and in particular to adjust the parameters inherent in the transmission

light.

  Referring now to FIG. 2a, it can be seen that the light source 2 comprises a plurality of light-emitting diodes 20 regularly arranged in the form of a matrix and secured to a support 21, for example by bonding, provided with electrical connections 22 making it possible to connect the diodes 20 to the power supply unit 11 and a bundle of optical fibers 23, one of whose ends for each optical fiber 23 is placed and held opposite the emitting surface of a light-emitting diode 20 of way to

  collect the light wave it emits.

  FIG. 2b shows a light-emitting diode 20 comprising an emission surface 25 located opposite and in the immediate vicinity of the input surface 26 of an optical fiber 23 coupled to said diode 2 and the dimensions of the input surface of which 26 of the fiber 23 are substantially identical to those of the emitting surface 25 of the diode 20 so as to collect the maximum of the active part of the surface 25

diode 20.

  The optical fibers 23 can be inserted into holes made in a plate, with a pitch of

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  drilling substantially identical to the distribution pitch of

diodes 20.

  The coupling of the diodes 20 thus produced with the optical fibers 23 therefore makes it possible to concentrate the light coming from the different diodes 20 and to obtain a

  lighting per large area unit.

  It can also be seen that the optical fibers 23 are joined and held at their other end in a ring 24 making it possible to obtain, at its output, an emission surface of small dimensions and a mixture of the light waves coming from the different optical fibers which will be routed through the waveguide 12 which is substantially the same diameter as the diameter of the ring 24. The waveguide 12 can be a liquid optical fiber having a very low line loss and offering good homogenization of the light emitted

  diodes 20 via optical fibers 23.

  The light-emitting diodes 20 can be controlled electrically either manually at the interface 13 by actuating keys 14 provided for this purpose, or by the central unit 10 by means of a program for controlling the power of the diodes 20

  acting on the supply unit 11 of the latter.

  As a result, the diodes 20 can be controlled as an all-or-nothing power supply, individually or in a package of diodes with the same emission spectrum, so as to be able to modify the emission spectrum of the light resultant at the output of the strand 24. It is also possible to modify the overall emission spectrum by varying the intensity of the electric current passing through the diodes 20, this variation being accompanied by a variation in the power emitted by

  the diode 20 which causes a variation of the global spectrum.

  Thus the variation of the current in a set of diodes 20 of a given spectral type will cause a modification of the emission power of the diodes 20 and therefore a variation of the spectrum of the light resultant.

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  at the output of the optical fiber network 23, just as the interruption of the supply of the diodes of one of its assemblies will modify, by deleting a spectrum, the spectral components of the light resultant at the output of the strand 24. The light-emitting diodes 20 will preferably be of the type without an optical coupling lens and the optical fibers 23 will preferably be fibers having a large numerical aperture to capture the maximum light emitted by the light-emitting diodes 20 and having a low linear attenuation in the fields wavelength used. In FIG. 3a we can see four curves 30, 31, 32, 33 which each represent the emission spectrum of a type of light-emitting diode 20 having a wavelength respectively, 380, 450, 520 and 820.m, for which the light emission is maximum. In this case the light-emitting diodes 20 whose spectrum is around 380 gm are particularly suitable for the treatment of materials more sensitive to ultraviolet, while the light-emitting diodes whose spectrum is around 450 gm are suitable for the treatment of materials composites of the family, for example, camphoroquinones and diodes whose spectrum is around 820 gm allow a thermal action on the

bleaching products.

  Thus the choice of the spectral characteristics of the light emitted by the light-emitting diodes makes it possible to obtain the desired spectral profile 34 (FIG. 3b) depending on the application, by adding the light emitted by the different diodes 20. Consequently, unlike to current systems which cause light losses at the level of the filtering devices preventing any modulation on the unfiltered areas the device according to the invention makes it possible to

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  to obtain the desired spectral profile and all the quantity

of light emitted.

  Note that due to the fact that the light-emitting diodes 20 have a low consumption of electric current, the energy supplied to the device can

  be made from rechargeable batteries or not.

  Advantageously the light-emitting diodes 2 can be secured on an interchangeable support provided with connectors allowing its

  quick connection to the device according to the invention.

  On the other hand so as to be able to modify the energy profiles memorized by the manufacturer in the read-only memory of the central unit 10 which can be programmed remotely by the user by means for example of a memory card of the card type to bullet containing the program including the parameters inherent in

the electrical control of the diodes.

  Remote programming of the microprocessor, which can also be carried out by means of a microcomputer via a modem-type interface, also allows the manufacturer of composite materials to optimize the spectrum of action of the light source according to its material. and provide after-sales service or an update very quickly and very

simply.

  Tests have shown that, in order to obtain a rapid polymerization which is desirable both clinically and biologically, the lighting provided by the light source 2 must be between 1 and 2 W / cm 2 and preferably around 1.5 W / cm 2. This lighting is directly related to the number of light-emitting diodes 20 and the power which is their

  supplied by the power card 11.

  It will be noted that the light source 2 can also be formed from a matrix of diodes supplied then imaged through an optical system on a photosensitive material which is then developed and

  drilled to serve as a support for optical fibers.

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  In addition, the diodes 20 can also be

deposited on a substrate.

  The device according to the invention therefore makes it possible to avoid any parasitic or dangerous radiation, which is not possible with current devices. -10-o 2789294

Claims (8)

  1) Apparatus allowing the photo activation of photosensitive composite materials used in particular in the dental field as well as the photo activation of product for teeth whitening of the type comprising a housing (1) containing an electric power supply unit (11) controlled electrically by an electronic central unit (10) and a light source (2) connected to said power supply (11) characterized in that said light source (2) consists of a plurality of light diodes (20) each associated with one or more optical fibers (23), which optical fibers (23) are intended to collect the light emitted by said diodes (20) and are joined and maintained so as to obtain at the exit of the network of optical fibers (20) the emitting surface as small as possible, said light emission being guided by an optical guide (12,12 '), optically connected to the outlet of said optical fibers (23), on the surface to be treated and in that the coupling between a diode (20) and one or more of said optical fibers (23) is carried out by optimally adjusting the emitting surface (25) of said diode (20) with the optical fiber or fibers ( 23) corresponding so as to collect the maximum of the active part of the light emission from each diode (20) in the corresponding fibers (23).   2) Apparatus according to claim 1 characterized in that the light diodes are   light emitting diodes (20) or laser diodes.   3) Apparatus according to claim 1 or claim 2 characterized in that the input of each fiber (23) is located either opposite and in the immediate vicinity of the emissive surface of the corresponding diode is opposite and in the immediate vicinity of an optical imaging device placed in front of the   emissive surface of said diode (20). -11- 2789294   4) Apparatus according to any one of   previous claims characterized in that the   diodes (2) are regularly arranged on a plate and in that the optical fibers (23) are each inserted into a hole with a diameter slightly greater than the diameter of said fibers and formed in a plate positioned by centering means near the plate supporting said diodes (2) and the pitch of the holes   is equal to that of the latter.   5) Apparatus according to any one of   previous claims characterized in that the   control of the power supply of the light-emitting diodes (20) is carried out manually by means of adjustment knobs (14,14 ') or automatically by means of the central unit (10) containing in its memory the parameters inherent in the control of said diodes (20) allowing   to obtain different energy profiles.   6) Apparatus according to any one of   previous claims characterized in that   the light emission at the outlet of the optical fiber bundle (23) comprises at least two wavelengths preferably situated respectively around 380 or 475gm and 750m, so as to obtain both the radiation necessary for certain composite materials and a radiation suitable for thermal action on   tooth whitening preparations.   7) Apparatus according to any one of   previous claims characterized in that the core   the waveguide (12) in which the light result propagates is made of plastic, glass, or is liquid.   8) Apparatus according to any one of   previous claims characterized in that   the power supply of the diodes is adjustable in pulsed mode so as to obtain higher instantaneous powers, favorable for applications particular polymerization.