WO2007045249A1

WO2007045249A1 - A dental handpiece

Info

Publication number: WO2007045249A1
Application number: PCT/DK2006/000587
Authority: WO
Inventors: Per Baekgaard
Original assignee: Dentofit A/S
Priority date: 2005-10-19
Filing date: 2006-10-19
Publication date: 2007-04-26

Abstract

The present invention relates to a dental handpiece comprising means for polymerization of a polymerizable resin base of a composite material, and means for generating an ultrasonic signal for martensitically transforming a filler ingredient of the composite material from a metastable first phase to a stable second phase. The present invention further relates to a method for polymerization of a resin base of a composite material and performing a martensitic transformation of a filler ingredient of the composite material.

Description

A DENTAL HANDPIECE

FIELD OF THE INVENTION

The present invention relates to a device and a method for automatic polymerization of a resin base of a composite material and martensitically transforming a filler ingredient of the composite material.

BACKGROUND OF THE INVENTION

EP 1 103 232 discloses a dental handpiece for the polymerization of photosetting resins or compounds comprising, as its polymerizing light source, at least one LED incorporated in the handpiece, the electrical supply signal for the LED light source being drawn from connectors of other types of hand pieces and being processed by means of an appropriate electronic circuit in order to make it suitable for bias of said LED light source. According to the system suggested in EP 1 103 232 it becomes easy to switch between various dental instruments, such as between a handpiece for polymerization and a scale. However, the dentist still needs to manually replace one type of instrument with another type of instrument.

A similar system is suggested in US 4,080,737 in that US 4,080,737 discloses a coupling device for detachably connecting a medical device, such as a dental handpiece, which requires at least one operating medium. The operating medium may be selected from a group consisting of electrical currents, propulsion gas, auxiliary gas, water and light and has a conduit for each of the required mediums, to a supply tube containing feed lines for at least one of the operating mediums. The coupling device includes a pair of coupling halves having coacting coupling links, and means for holding the coupling halves in coupling engagement. Each of the coacting coupling links is located in a specific spatial position in accordance with a pattern so that the coupling half attached to the supply tube can be utilized for coupling a different medical device which requires different selected operating mediums.

An ultrasonic dental insert having at least one light source is disclosed in US patent application 2005/0032017. In US 2005/0032017 a first transducer generates ultrasonic vibrations. A connecting body has a proximal end and a distal end having a tip attached thereto. The proximal end is attached to the first transducer so as to receive the ultrasonic vibrations therefrom and to transmit the ultrasonic vibrations toward the tip attached to the distal end. A second transducer is disposed substantially proximate to the connecting body for generating a voltage signal in response to movement of a portion of the connecting body according to the ultrasonic vibrations. At least one light source substantially proximate to the tip is connected to and receives the voltage signal from the second transducer to generate light. The ultrasonic dental insert may be inserted into a handpiece for providing electromagnetic energy to the first transducer to generate the ultrasonic vibrations.

According to the system suggested in US 2005/0032017 light is generated when the first transducer is activated. The generated light is directed onto the working area being prepared by the tip of the connecting body. The light serves no other purpose than illuminating the area being prepared by the tip.

It is an object of the present invention to provide a device and a method for automatic polymerization of a resin base of a composite material and martensitically transforming a filler ingredient of the composite material.

It is a further object of the present invention that the device and method martensitically transforms a filler ingredient of the composite material from a metastable first phase to a stable second phase, the volume ratio between said stable second phase and said metastable first phase of said filler ingredient being at least 1.005

SUMMARY OF THE INVENTION

The above-mentioned objects are complied with by providing, in a first aspect, a dental handpiece comprising

- means for polymerization of a polymerizable resin base of a composite material, and

- means for generating an ultrasonic signal for martensitically transforming a filler ingredient of the composite material from a metastable first phase to a stable second phase, the volume ratio between said stable second phase and said metastable first phase of said filler ingredient being at least 1.005.

Thus, the present invention combines in one single device appliance of light for curing of dental composite resins and ultrasonic sound aimed to phase convert parts of the filler content of the composite resin hereby obtaining an essentially volume stable composite filling. This technique solves the problem of known resins which shrink due to the unavoidable contraction of the resin part of the composite compound during polymerization when this takes place at normal atmospheric pressure and room temperature.

It is possible to outbalance this shrinkage by expanding a part of the normally inactive filler content. The expansion is caused by phase conversion of a crystal inside the resin. The exact time of the phase conversion must be controlled precisely to counteract the polymerisation shrinkage, as these ideally should be simultaneously. The energy needed to trigger the phase conversion may be supplied by an ultrasonic device.

In order for the dentists not to have two devices to use within stringent timing in the oral cavity of the patient, the present invention combines the traditional LED-lamp for curing with an ultrasonic source for inducing phase conversion. This both eliminates sources for treatment errors, as the timing between curing and phase conversion can be pre-determined and pre-programmed and offers a better convenience to the patient and dentist when only one single device has to be applied.

The polymeriszation means may comprise a light source, such as a LED or a laser diode. Preferably, the light source emits light having a wavelength within the range 400-550 nm, such as approximately 470 nm. The light source may emit light having an output power within the range 1-100 mW.

The means for generating the ultrasonic signal may comprise a piezoceramic resonator. This piezoceramic resonator may be adapted to oscillate at a oscillation frequency ranging from 20 kHz to 45 kHz so as to generate an ultrasonic signal within this range.

The dental handpiece according to this first aspect of the present invention may further comprise a control module for controlling the polymerization means and ultrasonic generation means. The control module may at least be adapted to control applied time periods for the polymerization means and ultrasonic generation means. By applied time periods is meant the time periods during which the polymerization means and ultrasonic generation means are active. The control module may further be arranged to control how the polymerization means and ultrasonic generation means are activated relative to each other. In one embodiment active time periods for the polymerization means and ultrasonic generation means may be pre-programmed into the control module. Similarly, an optional and adjustable time delay between switching the polymerization means and ultrasonic generation means on and off may be pre-programmed into the control unit.

Pre-programmed system parameters may be displayed on a visible display member, such as an LCD-panel.

In a second aspect, the present invention relates to a method for polymerization of a resin base of a composite material and performing a martensitic transformation of a filler ingredient of the composite material, the method comprising the steps of - exposing the composite material to electromagnetic radiation so as to initiate polymerization of the resin base, and

- exposing the composite material to an ultrasonic signal for so as to initiate the martensitic transformation of the filler ingredient from a metastable first phase to a stable second phase, the volume ratio between said stable second phase and said metastable first phase of said filler ingredient being at least 1.005.

Again, the electromagnetic radiation may have a wavelength within the range 400-550 nm, such as approximately 470 nm, and a power within the range 1-100 mW. The ultrasonic signal may oscillate at a oscillation frequency ranging from 20 kHz to 45 kHz.

BRIEF DESCRIPTION OF THE INVENTION

The present invention will now be explained in further details with reference to the accompanying figure, wherein

Fig. 1 shows a device according to the present invention.

While the invention is susceptible to various modifications and alternative forms, a specific-embodiment has been shown by way of example in the drawing and will be described in detail herein. It should be understood, however, that the invention is not intended to be limited to the particular forms disclosed. Rather, the invention is to cover all modifications, equivalents, and alternatives falling within the spirit and scope of the invention as defined by the appended claims.

DETAILED DESCRIPTION OF THE INVENTION

In its most general aspect the present invention relates to a device and a method which combines the possibility of curing dental composite resins with the possibility of phase converting crystals by supplying the sufficient energy from an ultrasound source.

Referring now to Fig. 1 an embodiment of the present invention is depicted. Fig. 1 shows a cordless, handheld device which is adapted to be charged by placing it in a docking device. The handheld device includes a handle which houses a rechargeable battery. In the bottom part of the handle a connector unit for providing electrical connections to a docking device is positioned. On the top part of the handle two push buttons are oppositely arranged. One of these push buttons activates a curing lamp whereas the other push button activates an ultrasonic source. The wavelength of the light emitted by the curing lamp is preferably around 470 nm. LEDs or laser diodes are suitable light sources. The output power of the LED or laser diode is within the range 1-100 mW. The frequency of the ultrasound generated by the ultrasonic source is between 20 and 45 KHz.

The curing light is guided within the handheld device so that it illuminates a region spatially overlapping with the tip of the ultrasonic source. Thus, by ensuring a sufficient spatial overlap between the tip of the ultrasonic source and the curing light the same site can be exposed to both curing light and ultrasonic treatment without moving the handheld device. The fact that the dentist can perform multiple treatments using the very same dental instrument reduces the required time of treatment for patients.

The time setting for the curing light is programmable. Thus, by activating the control button for the curing lamp the curing lamp will be switched on for a predetermined period of time. The offset of the ultrasound is typically between 5 and 30 seconds. Thus, the generation of ultrasound is automatically initiated between 5 and 30 seconds after the curing has started. However, it is also possible to start appliance of ultrasound manually. Pre-programmed system parameters can be displayed on the visible display of the handheld device.

Claims

1. A dental handpiece comprising

2. A dental handpiece according to claim 1, wherein the polymeriszation means comprises a light source, such as a LED or a laser diode.

3. A dental handpiece according to claim 2, wherein the light source emits light having a wavelength within the range 400-550 nm, such as approximately 470 nm.

4. A dental handpiece according to claim 2 or 3, wherein the light source emits light having an output power within the range 1-100 mW.

5. A dental handpiece according to any of the preceding claims, wherein the means for generating the ultrasonic signal comprises a piezoceramic resonator.

6. A dental handpiece according to claim 5, wherein the piezoceramic resonator is adapted to oscillate at a oscillation frequency ranging from 20 kHz to 45 kHz.

7. A dental handpiece according to any of the preceding claims, further comprising a control module for controlling the polymerization means and ultrasonic generation means, the control module at least being adapted to control applied time periods for the polymerization means and ultrasonic generation means.

8. A method for polymerization of a resin base of a composite material and performing a martensitic transformation of a filler ingredient of the composite material, the method comprising the steps of

- exposing the composite material to electromagnetic radiation so as to initiate polymerization of the resin base, and - exposing the composite material to an ultrasonic signal for so as to initiate the martensitic transformation of the filler ingredient from a metastable first phase to a stable second phase, the volume ratio between said stable second phase and said metastable first phase of said filler ingredient being at least 1.005.

9. A method according to claim 8, wherein the electromagnetic radiation has a wavelength within the range 400-550 nm, such as approximately 470 nm.

10. A method according to claim 8 or 9, wherein the electromagnetic radiation has a power within the range 1-100 mW.

11. A method according to any of claims 8-10, wherein the ultrasonic signal oscillate at a oscillation frequency ranging from 20 kHz to 45 kHz.