A METHOD AND AN APPARATUS FOR INCREASING THE DISSOLVING RATE OF CARIOUS DENTINE

Abstract: The invention relates to a method and an apparatus for increasing the dissolving rate of carious dentine in a chemo-mechanical treatment method for caries (2) by means of a caries dissolving preparation (4) which is applied on the carious lesion for dissolving the carious dentine. A vibration transmitting element (1) is brought into contact with the caries dissolving preparation (4), which has been applied to the carious lesion, for transmitting vibration energy into the preparation. The transmitted vibration energy has a frequency within the range from audible sound up to supersonic frequencies. This increases the diffusion rate of the active component in the preparation (4) and the treatment period is shortened. The vibration transmitting element (1) is preferably the tool head of a scraping instrument for removing the dissolved carious tooth substance.

Description: A method and an apparatus for increasing the dissolving rate of carious dentine. The present invention relates to a method and an apparatus for increasing the dissolving rate of carious dentine in a chemo-mechanical treatment method for removing caries by means of a caries dissolving preparation which is applied on the carious lesion for dissolving the carious dentine. In traditional caries treatment methods the caries attacked dental substance is removed mechanically by means of a dentist's drill or a cutting excavator. Such a caries treatment is often a painful and unpleasant experience for the patient. Some of the patients feel so uncomfortable with the treatment that they wait far too long before they visit a dentist, which means that it is often too late to save the caries attacked teeth. Extraction of the teeth is then the only treatment method that is left. However, there are other methods which are based on a chemo-mechanical treatment for the removal of the carious substance. Such methods are described in SE 460258, SE 507437 and SE 98.00025-0. According to these methods a preparation in the form of a two-component liquid is mixed and then immediately applied to the carious lesion. Functioning in a biological way, the liquid makes the caries attacked substance soft without causing any damage to the tooth or the soft tissue. After 10-15 seconds the dentist can start removing the softened carious substance by means of an excavator. The excavating procedure continues until all caries substance has been removed. Then the cavity is filled with a suitable filling material. According to SE 460258 the two-component liquid consists of a sodium hypochlorite component and an amino acid component. Sodium hypochlorite has a strong dissolving effect on the caries attacked substance and is the active component in the liquid. The amino acids reduce the reactivity, and thereby the aggressivity against sound tissue, of the sodium hypochlorite component. The two components are mixed together just before use and then applied directly to the carious lesion. The caries dissolving effect starts when the liquid with the active component comes into contact with the carious attacked tooth surface. The two-component liquid is dispersed by means of diffusion in the carious substance and in order to increase the velocity of the caries dissolving effect and thereby reduce the treatment period of time it is desirable to increase the diffusion rate by reducing the diffusion distance and/or the diffusion velocity, see below. Unlike traditional mechanical caries treatment methods the biological treatment method is usually not painful at all. Neither does it require any investments in expensive equipments. It only requires an excavator instrument to remove softened carious dentine material. Traditional excavator instruments, however, are not suitable for this purpose as they are cutting and not made for just scraping away already softened dentine material from different types of cavities and therefore could damage healthy dentine. — An instrument specifically made for removing softened carious dentine is previously disclosed in SE 96.04626-3. This instrument makes it possible to manually scrape in different directions and the scraping edges of the tool head of the instrument are adapted to all types of caries lesions. The instrument comprises a star-shaped tool head having four symmetrically arranged scraping edges with a curved, preferably spherical, outer contour (periphery) for scraping away softened carious substance. The instrument can also be used for catching drops of the liquid solution used for the chemo-mechanical treatment method and carry these drops to the site of the caries attacked tooth part. This is possible because of the open, empty spaces which are located between the scraping edges of the tool head of the instrument and this function of the instrument is facilitated as the liquid solution which is used has a viscous, gel form. So by using this type of scraping instrument which then also functions as a simple applicator for the viscous liquid used for the treatment, there is no need for the dentist to invest money in any expensive equipments for distribution and application of the liquid solution. However, in cases where the carious lesion has a very hard surface it might be comparatively time-consuming to use any of said previously known instruments. It takes more time for the preparation to soften the surface of the carious lesion and the scraping edges have primarily not a sufficient "biting effect" on the hard surface. Also, it is not desirable for the dentist or the patient to apply too much forces in the scraping operation. It should not be allowed to apply too heavy moments from the instrument on the tooth. In SE 98.03057-0 it is illustrated an instrument which is able to roughen the surface so that it takes less time for the solution to soften the carious lesion, which means that the softened caries substance then can be removed more quickly. By designing the scraping edges with transverse grooves so that they are able to scratch and roughen the hard surface, the effective surface area for the treatment solution is increased and the treatment period of time is shortened. A common feature of these instruments is the fact that they are made for manually scraping away softened, carious dentine, i e. the scraping motion is fully made by hand. As the scraping motion should be carried out in different directions and repeated until all carious dentine has been removed, it might be a hard work for the dentist from an ergonomically point of view to carry out the caries treatment procedure. The dentist has to position the instrument as well as he must control the instrument with respect to the scraping direction. At the same time the scraping motion should not affect any of the healthy teeth. It should not be allowed to apply too heavy pressure from the instrument on the tooth. In order to unload the way of working (the specific scraping motion) from the dentist so that he can better concen- trate on positioning the instrument it is previously known to use machine scraping instruments also in this type of carious treatment, see SE 98.02868-1. Then the instrument is equipped with, or connected to, for instance an electric motor for driving the tool head of the instrument ac- cording to a predetermined motion pattern. For instance it could be a rotating, low-speed motion, a reciprocating motion, a pendulating, wobbling or oscillating motion. According to a preferred embodiment the instrument has a star-shaped tool head and a shaft for connecting the in- strument to a rotating machine (power tool). By means of such an instrument a more efficient scraping operation is achieved, the treatment procedure is speeded up and each caries treatment procedure is shortened. In addition to just having a scraping function, i e scraping away softened carious dentine, the scraping instrument also fulfils an important function by stiring in the carious lesion so that more and larger contact surfaces between the two-component liquid and carious dentine are formed. The diffusion path for the active component up to the carious lesion surface can then be shortened. This is also the case for the period of time for dissolving all the caries material . The caries dissolving rate substantially depends on: 1. Type of caries. Some caries is re-mineralized by for instance saliva. This type of caries is more difficult to stir and remove. 2. Chemistry. The aggressivity of the active component, the sodium hypochlorite or other chloride compounds containing active chloride with a net charge of +1, has an influence on the dissolving rate. However, the aggressivity should not be too high as sound tissue then might be affected. 3. The stiring technique. The stiring with the scraping instrument should be performed in such a way that new gel is continuously transferred to the carious lesion surface, that many and large contact surfaces are formed from which the diffusion path to the reaction place is short. To increase the dissolving rate by increasing the aggressivity of the active component is not a good idea because of the risk for affecting sound tissue. To improve the stiring technique, for instance by using a machine scraping instrument of the above-mentioned type, could be one way to increase the dissolving rate, i e to shorten the period of time until all caries has been dissolved. However, it is desirable to increase the dissolving rate even more in order to reduce the treatment period of time for a patient. It has been proposed to increase the diffusion rate by heating the tooth and the two-component liquid. However, the temperature range that can be used for this purpose is limited. Even if the teeth and the oral cavity itself can stand a relatively large temperature change - compare for instance the situation when drinking hot coffee - the tissue might be damaged if the tempera- ture is increased too much. Another disadvantage with the heating treatment is the fact that excessive heating of the carious tooth might be painful for the patient, which of course is unsatisfactory. Another way to increase the diffusion rate is to make the caries dissolving solution less viscous. However, this is not a good idea either, as it makes the liquid more difficult to handle, it increases the risk that the liquid is spread out unintentionally and irritates the surrounding soft tissue as well as the risk of spillage. This is instead one reason for adding a viscous increasing substance (gel substance) to the preparation. It is an object of the present invention to provide an apparatus or an instrument for increasing the diffusion rate, i e to shorten the period of time for the caries to be dissolved so that the caries treatment period of time also can be shortened, but without the disadvantages that have been mentioned above. A further object of the invention is to provide an instru- ment which adds energy to the liquid in order to increase the diffusion rate of the active component without any-undesirable heating of the tooth and the carious lesion. The instrument could be used separately or combined with an existing scraping instrument. According to the invention the apparatus comprises a vibration transmitting element which is brought into contact with the caries dissolving preparation which has been applied to the carious lesion and transmits vibration energy to the preparation, the transmitted vibration energy having a frequency within the range from audible sound to ultrasonic frequencies . According to a preferred embodiment the vibration transmitting element is made as a tool head with a scraping function. In addition to said vibration transmitting tool head the instrument then also comprises a connecting part for connecting the instrument to vibration generating means . In the following some examples of instruments according to the invention will be described more in detail with refer- ence to the accompanying drawings, wherein figure 1 is an overall view of the instrument for caries treatment, figure 2 illustrates the carious lesion and the vibration transmitting element more in detail, and figure 3 illustrates another embodiment of the instrument. As illustrated in figure 1 the instrument comprises a tool head or working member 1 having a spherical outer contour. The tool head is intended to be used for scraping a caries lesion 2 in a tooth 3 in a chemo-mechanical caries treatment procedure by means of a caries dissolving preparation 4 applied to the caries lesion. The tool head has in this case a star-shaped geometry formed by three symmetrically arranged scraping edges 5 having a circular periphery, see figure 2. The scraping edges 5 are extending radially outwards in three different directions and thanks to the cir- cular periphery both the bottom and the sides of the cavity can be scraped with one and the same star-shaped tool head 1. The tool head itself could have the same form as in the instrument illustrated in SE 9604626-3 and in which the scraping motions are made out completely by hand. Similar to the previously known instrument, of course also this instrument could have more or less than three symmetrical- ly arranged scraping edges . In contrast to the previously known instrument, in which two tool members are arranged with a hand grip member therebetween for handling the instrument entirely by hand, the instrument according to the present invention has a bent connecting part (shaft) 6 for connecting the instrument to an oscillator 7 for vibrating the tool head 1. In this case, therefore, the tool head is also the vibration transmitting element or body which is brought into contact with the caries dissolving preparation 4 applied to the caries lesion and transmitting the vibrations into the solution. The oscillator 7 is for instance a piezo-electric element or a magnetostriction oscillator. The oscillator itself is connected to a driving unit 8 with the necessary electronics for generating oscillations in the frequency range from audible sound up to ultrasonic frequencies, i e in the frequency range of 1000 Hz - 20 kHz for the audible sound and frequencies over 20 kHz for supersonics. The use of vibration energy in the frequency range from audible sound up to supersonic frequencies is known per se in many applications, for instance for increasing the diffusion in a detergent solution in a supersonic bath. Also in the dental field it is previously known to use ultrasonic instruments for removing dental deposits and plaque. Then the instrument has a sharp cutting edge which is chopped into the dental plaque by means of the vibrations and breaks up the hard plaque. In our case the vibration energy is transferred to the preparation, the two-component solution, which has been applied to the tooth, by dipping the vibration transmitting element down into the preparation in order to increase the diffusion rate and the stirring effect in the preparation itself in order to speed up the dissolution of the carious dentine. The scraping and removal of the soft carious dentine can then be effectuated by means of the scraping instrument according to the previous treatment procedure and without the addition of vibration energy in this stage. The oscillating means 7 and 8 for the instrument consists of components which are known per se and will not be described in any detail here. Furthermore the instrument has a handle 9 or connecting shaft to a rotary machine in case a machine instrument is used. The instrument also has a cable 10 for the electricity supply to the vibration generating components 7 and 8. In figure 2 the zone 13 where the caries dissolving preparation has been mixed with carious dentine substance is schematically illustrated and also the diffusion interface 14 to the carious dentine has been indicated. In figure 3 it is illustrated another embodiment of the instrument in which the vibration generating element comprises a sleeve-shaped member 11 connected to the vibration generating components (not shown) and which is arranged coaxially with the tool part 12 of the scraping in- strument. When sound - ultrasonic energy is transmitted from the vibration transmitting element to the carious lesion and the caries dissolving preparation, for instance the Caπsolv gel which is available from editea Dentalutveckling i Goteborg AB for chemo-mechanical treatment of caries, and which has been applied to the carious dentine, then the vibrations in the preparation improve the stirring effect and increase the diffusion rate for the active component in the preparation. In this way it is possible to shorten the treatment period of time substantially. The invention is not limited to the examples that have been described here, but can be varied within the scope of the accompanying claims.

Claims: CLAIMS 1. A method for increasing the dissolving rate of carious dentine in a chemo-mechanical treatment method for remov- ing caries by means of a caries dissolving preparation which is applied on the carious lesion for dissolving the carious dentine c h a r a c t e r i s e d b y bringing a vibration transmitting element ( 1 ) into contact with the caries dissolving preparation (4), which has been applied to the carious dentine, in order to transmit vibration energy into the preparation, the transmitted vibration energy having a frequency within the range from audible sound up to ultrasonic frequencies. 2. A method according to claim l c h a r a c t e r i s e d b y transmitting the vibration energy to the preparation ( 4 ) by means of the scraping instrument used for removing the dissolved carious tooth substance. 3. A method according to claim 2 c h a r a c t e r i s e d b y using the tool head ( 1 ) of the scraping instrument as vibration transmitting element. 4. An apparatus for increasing the dissolving rate of car- ious dentine in a chemo-mechanical treatment method for caries (2) by means of a caries dissolving preparation— (4 ) which is applied on the carious lesion for dissolving the carious dentine c h a r a c t e r i s e d b y a vibration transmitting element ( 1 ) arranged to be brought into contact with the caries dissolving preparation (4) which has been applied to the carious lesion and transmit vibration energy into the preparation, the transmitted vibration energy having a frequency within the range from audible sound up to ultrasonic frequencies. 5. An apparatus according to claim 4 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is the tool head of a scraping instrument for removing dis- solved carious tooth substance. 6. An apparatus according to claim 4 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is a separate member with respect to the scraping instrument. 7. An apparatus according to claim 4 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is a member connectable to the scraping instrument, for in- stance a sleeve member (11) coaxially arranged with respect to the tool part of the scraping instrument. 8. An apparatus according to claim 4 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is connected to vibration generating components (7,8) via a connecting shaft (6). 9. An apparatus according to claim 8 c h a r a c t e r is e d i n that the vibration generating components com- prise an oscillator (7) for generating a vibration frequency within the ultrasonic frequency range, preferably about 50 kHz. AMENDED CLAIMS [received by the International Bureau on 10 July 2000 (10.07.00); original claims 1 -9 replaced by new claims 1 -6 (2 pages)] 1. An apparatus for increasing the dissolving rate of carious dentine in a chemo-mechanical treatment method for caries (2) by means of a caries dissolving preparation (4) in the form of a two component solution in which one of the components is an active component which has a dissolv- ing effect on the carious substance, which preparation is applied on the carious lesion for dissolving the carious dentine c h a r a c t e r i s e d b y a vibration transmitting element ( 1 ) arranged to be brought into contact with the caries dissolving preparation (4) which has been applied to the carious lesion and transmit vibration energy into the preparation in order to increase the diffusion rate of the active component, the transmitted vibration energy having a frequency within the range from audible sound up to ultrasonic frequencies. 2. An apparatus according to claim 1 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is the tool head of a scraping instrument for removing dissolved carious tooth substance. 3. An apparatus according to claim 1 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is a separate member with respect to the scraping instrument. 4. An apparatus according to claim 1 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is a member connectable to the scraping instrument, for instance a sleeve member (11) coaxially arranged with respect to the tool part of the scraping instrument. 5. An apparatus according to claim 1 c h a r a c t e r is e d i n that the vibration transmitting element ( 1 ) is connected to vibration generating components (7,8) via a connecting shaft (6). 6. An apparatus according to claim 5 c h a r a c t e r is e d i n that the vibration generating components com- prise an oscillator (7) for generating a vibration frequency within the ultrasonic frequency range, preferably about 50 kHz.

Inventors: CARLSSON LENNART, CARLSSON, LENNART
Applicants: CARLSSON LENNART, MEDITEAM DENTALUTVECKLING I GO, CARLSSON, LENNART, MEDITEAM DENTALUTVECKLING I GOETEBORG AB
Application year: 2000
Main classification: A61C3
IPC codes: A61C3, A61C5, A61C17, A61C19