DENTAL INSTRUMENT

Abstract: The invention relates to a dental instrument for removing caries attacked dentine in connection with chemical-mechanical treatment of caries by means of a caries-dissolving solution applied to the caries for loosening the caries tooth substance. The instrument comprises a tool head (4, 5) with a number of curved, longitudinal scraping edges (6), i.e. edges which are extending in the longitudinal direction (9) of the instrument, for scraping away softened caries tooth substance. One or more of the longitudianl and curved scraping edges (6) has transverse grooves (7) so that a number of scraping edges (8) are formed also transverse to the curved, longitudinal edges (6). By such means a hard caries surface is more efficiently roughened by the instrument which means that the softening time is reduced so that the softened caries can be removed more quickly. By designing the scraping edges so that they can scratch and roughen the hard surface, then the actual surface area on which the solution is acting is increased which means a reduced treatment period.

Description: Dental instrument The present invention relates to a dental instrument for removing caries attacked dentine. In traditional caries treatment the attacked tooth 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 chemical-mechanical treatment for the removal of the caries attacked 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 on the caries site. 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 sec- onds the dentist can start removing the carious substance by means of an excavator. The excavating operation 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 a nitrogen-containing component. The nitrogen-containing component consists in this case of three nitrogen-containing compounds with different charge states in its side chain; one neutral, one with a negative net charge and one with a positive net charge. Unlike conventional 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 attacks. 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 chemical-mechanical treatment method and carry these drops to the site of the caries at- tacked 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 substance 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 attack has a very hard surface it might be very time-consuming to use any of said previously known instruments. It takes more time for the solution to soften the surface of the caries attacked region 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. It is therefore an object of this invention to provide an instrument which is able to roughen the surface so that it takes less time for the solution to soften the caries attacked portion, which means that the softened caries substance then can be removed more easily. By designing the scraping edges so that they are able to scratch and roughen the hard surface, then the surface area for the treatment solution is increased which also speeds up the treatment period. According to the invention the instrument comprises a tool head having one or more longitudinal scraping edges with a curved outer contour and transverse grooves so that a number of scraping edges is formed also transverse to the curved, longitudinal edges. According to a preferred embodiment the lateral edges have a V-shaped section so that the longitudinal curved scraping edge is substantially forming a sawtooth geometry. In the following an example of an instrument according to the invention will be described more in detail with reference to the accompanying drawings , wherein figure 1 is an overall view of the instrument, and figure 2 illustrates the tool head more in detail. As illustrated in figure 1 the instrument generally com- prises two tool members 1 , 2 with a grip member 3 therebetween. The two tool members are angulated in order to facilitate the use of the instrument in the mouth of a patient. The two tool heads 4,5 have a substantially, spher- ical outer contour formed by a number of scraping edges extending radially outwards. As the scraping edges are substantially longitudinal, i e they are extending in the longitudinal direction of the instrument, and curved, preferably circular, the tool heads are forming a star- shaped geometry with a substantially spherical outer contour. Such an instrument is previously described in SE 96.04626-3. In contrast to previous instruments of this type wherein each of the scraping edges is forming a curved, continuous line the instrument according to this invention has a number of transverse grooves 6 on the longitudinal edges 7 so that a number of cutting edges 8 are formed also transverse to the longitudinal edges 7, which are parallell to the longitudinal axis 9 of the instrument, see figure 2. In the embodiment illustrated in figure 2 the tool head has four longitudinal scraping edges 7 and four transverse grooves 6. The grooves 6 are V-shaped so that the scraping edges 7 are forming a sawtooth geometry. This means that each of the scraping edges 7 also has three scraping edges 8 extending transverse to the longitudinal edge 7. By means of said transverse scraping edges 8 a hard, car- ies-attacked dental surface is more easily roughened, for instance by small back-and-forward movements, so that the used solution could more rapidly soften the caries . Otherwise the instrument is used in the same way as the previous instruments for application of the used solution through the spaces between the scraping edges and then for removing the carious, softened tooth substance. It should be understood that the instrument according to the invention could have more or less than four longitudinal scraping edges 7 and more than four transverse grooves 6. By increasing the number of scraping edges the tool head will be more "solid", like a ball with a wafer or rutile surface structure, or like a spherical spike head. Such a design might be more useful for roughening a hard dental surface, but as soon as the carious tooth substance is soft enough, the previously known type of instrument might then be required for removing the softened caries substance. In a hand-held instrument of the type which is illustrated in figure 1 , either both or only one of the tool heads 4 , 5 might be designed according to the invention. For instance one of the tool heads could be designed with transverse grooves according to the invention, while the other tool head could be designed according to the previously mentioned patent SE 96.04626-3. It should also be understood that the tool head, instead of the design illustrated in figure 1, could have a shaft 10 connectable to a machine instrument of the type which is described in SE 98.02868-9. A machine instrument provides a more controlled scraping movement which makes a tool head according to this invention more efficient. Preferably, the tool head could be included in a set of different instruments to be used in the chemical-mechanical treatment method and which then could be connected to one and the same machine instrument. The invention is not limited to the example which is illustrated in the specification and on the figure, but can be varied within the scope of the accompanying claims . For instance, the transverse grooves could have another pro- file, U-formed, rectangular etc. Then the cutting angle of the transverse edges 8 will be more sharp.

Claims: CLAIMS 1. Dental instrument for removing caries attacked dentine in connection with chemical-mechanical treatment of caries by means of a caries-dissolving solution applied to the caries for loosening the caries substance, said instrument comprising a tool head (4,5) with a number of curved, lon- gitudinal scraping edges (6), i.e. edges which are extending in the longitudinal direction of the instrument, for scraping away softened caries tooth substance c h a r a ct e r i z e d in that one or more of the longitudinal and curved scraping edges (6) has transverse grooves (7) so that a number of scraping edges (8) are formed also transverse to the curved, longitudinal edges (6). 2. Instrument according to claim 1 c h a r a c t e r i ze d by two tool heads (4,5) with a grip member ( 3 ) there- between for manual use of the scraping instrument, at least one of the tool heads having such transvers grooves (7). 3. Instrument according to claim 2 c h a r a c t e r i z- e d i that the tool head member is connectable to a machine instrument to provide to the tool head (4,5) a controlled scraping movement. 4. Instrument according to claim 1 c h a r a c t e r i z- e d i n that the transverse grooves (7) have a V-shaped section. 5. Instrument according to claim 1 c h a r a c t e r i ze d i n that the transverse grooves ( 7 ) have a U-shaped or rectangular section. 6. Instrument according to claim 1 c h a r a c t e r i ze d in that the tool head (4,5) has a substantially spherical outer contour with a number of longitudinal as well as transverse edges (6,8) or points. 7. Instrument according to claim 6 c h a r a c t e r i ze d in that the tool head (4,5) is star-shaped with preferably four longitudinally and symmetrically arranged scraping edges (6) with a number of transverse grooves (7) to form a sawtooth geometry.

Inventors: STJERNKVIST THOMAS, SVENSSON THOMAS, STJERNKVIST, THOMAS, SVENSSON, THOMAS
Applicants: MEDITEAM DENTALUTVECKLING I GO, STJERNKVIST THOMAS, SVENSSON THOMAS, MEDITEAM DENTALUTVECKLING I GOETEBORG AB, STJERNKVIST, THOMAS, SVENSSON, THOMAS
Application year: 1999
Main classification: A61C3
IPC codes: A61C3, A61C19