Dental power tool

Abstract: A dental power tool (11) is provided with a guard device (4) incorporating a guard plate (10) for keeping a possible obstacle, e.g. the tongue (5a) or a part of the inside wall of a lip, aside during the dental treatment.

Description: The present invention relates to a dental power tool of e.g. air turbine operated or contra-angle type for cutting a decayed tooth. For treatment of a decayed tooth, a combination is commonly utilized of a dental tool for cutting a decayed tooth, a vacuum nozzle for removing a pool of oral liquid produced during the treatment, and a mirror for keeping an obstacle, e.g. the tongue or a part of oral body, from disturbing an action of the treatment. More specifically, as shown in Fig. 54, the dental tool A and the mirror B are held by both the hands C, D of a dentist for treatment of a decayed tooth E while the vacuum nozzle F is gripped by the hand of a hygienist. This will be a troublesome task and require a considerable cost. Also, appropriate cooperation between the dentist and the hygienist will be essential for carrying out a dental treatment efficiently. However, hygienists are substantially limited in number and not easily available because of today's labour shortage. For compensation, the dentist attempts to use the vacuum nozzle F to keep the obstacles aside during cutting a decayed tooth instead of the mirror B, or places it in the corner of the mouth of a patient. As a result, the pool of oral liquid will not be removed succesfully and/or the patient to be treated will feel unpleasant. It would be desirable to eliminate the foregoing drawbacks, by providing an improved dental tool capable of cutting a decayed tooth efficiently without the help of a hygienist while giving no more discomfort to the patient. US-A-2 671 269, US-A-2 924 013, CH-A-602 086, and EP-A-155 206 all disclose dental power tools in accordance with the pre-characterising part of claim 1. In each case a guard device is mounted directly on the rotary head to which the cutting bit is attached; this is remote from the tool body held by the dentist's hand. The present invention provides a dental power tool for treatment of a decayed tooth, comprising: a tool body to be held by the dentist's hand; a high-speed rotary head mounted to the front end of the tool body; a cutting bit detachably attached to the rotary head; and a guard device including a guard plate adjacent to the cutting bit for keeping aside a possible obstacle, such as the tongue or a part of the inside wall of a lip, during the dental treatment; characterised in that the guard plate is mounted on the front end portion of an elongate arm which extends along the dental power tool, the rear end portion of the arm being mounted on a fitting ring which is mounted on a proximal portion of the tool body, thereby leaving the distal portion of the tool body free to be gripped by the dentist's hand which can at the same time manipulate the guard device. Preferred and optional features are set forth in the subsidiary claims. The invention will be described further, by way of example, with reference to the accompanying drawings, in which: Fig. 1 is a side view showing a first embodiment of the present invention; Fig. 2 is a plan view of the first embodiment; Fig. 3 is a front view of the first embodiment; Fig. 4 is a perspective view of a guard device; Figs. 5 to 10 are explanatory views showing an application of the first embodiment; Figs 11 to 18 are explanatory views showing a second embodiment of the present invention; Figs. 19 to 26 are omitted; Figs. 27 to 29 show a third embodiment; Figs. 30 and 31 show a fourth embodiment; Figs. 32 to 35 show a fifth embodiment; Figs. 36 to 38 show a six embodiment; Figs. 39 to 41 show a seventh embodiment; Figs. 42 to 45 are omitted; Figs. 46 and 47 show an eighth embodiment; Figs. 48 to 50 show a ninth embodiment; Figs. 51 to 53 show a tength embodiment; Fig. 54 is an explanatory view showing a traditional manner of cutting a decayed tooth. Preferred embodiments of the present invention will be described referring to the accompanying drawings. According to a first embodiment of the present invention illustrated in Figs.1 to 10, there are provided a main body 1 of a dental power tool such as an air turbine hand-piece or motor-powered contra-angle rotary tool which provides at front end a jet of water and can be held by hand, a high-speed rotary head 2 arranged at the front end of the dental tool body 1, and a cutting bit 3 detachably mounted to the high-speed rotary head 2. There is also provided a guard device 4 which extends from the dental tool body 1 for keeping an obstacle, e.g. the tongue or inside wall of a lip, in the mouth away from the cutting bit 3 during the operation. The guard device 4 comprises a fitting ring 6 slidably fitted onto a tapered proximal portion of the dental tool body 1, an arm 7 fixedly mounted at rear end to the fitting ring 6 so as to extend towards the side of the cutting bit 3, and a guard plate 10 consisting of a vertical holding tab 8 mounted integrally to the front end of the arm 7 to extend upward and downward in half-round shape and a front holding tab 9 of half-round shape extending frontward from a central portion of the vertical holding tab 8. For dental treatment on a decayed tooth at the lower left as shown in Fig.5, the foregoing assembly or dental tool 11 is operable with its guard plate 10 keeping the tongue 5a aside while a vacuum nozzle 12 is applied to the outside of the decayed tooth to be treated for keeping the inside wall 5b of a lower lip away and simultaneously, removing a pool of oral liquid. For dental treatment on a decayed tooth of at the lower right as shown in Fig.6, the dental tool 11 is operable with its guard plate 10 keeping the lip inside wall 5b aside while the vacuum nozzle 12 presses against the tongue 5a and removes a pool of oral liquid. For the same purpose at the upper left of the dentition, the guard device 4 of the dental tool 11 is shifted by moving forward to disengage the fitting ring 6 from the dental tool body 1, turning the guard plate 10 through 180 degrees, and moving backward to fit the fitting ring 6 onto the dental tool body 1, as shown in Figs.7 and 8. The treatment can then be carried out in an equivalent manner while the guard plate 10 keeps the tongue 5a aside and the vacuum nozzle 12 presses against the inside wall 5b of an upper lip, as shown in Fig.9. Similarly, the dental treatment at the upper right can be done while the guard plate 10 of the guard device 4 keeps the lip inside wall 5b and the vacuum nozzle 12 presses against the tongue 5a. Other embodiments of the present invention will now be described referring to Figs.11 to 53. For ease of the description, like components as those in the first embodiment are denoted by like numerals and will not be explained any further. A second embodiment of the present invention shown in Figs.11 to 18 differs from the first embodiment by the fact that the guard device 4 is replaced with a modified guard device 4A in which an arm 7 has a mirror 14 mounted by a bent portion 13 to the distal end thereof at an angle such that it is equally tilted when the arm 7 turns 180° and acts as the guard plate. Accordingly, a dental tool 11A provided with the guard device 4A, like the dental tool 11 of the first embodiment, can successfully be used for treatment on a decayed tooth at the lower left, as shown in Fig.15, at the lower right as shown in Fig.16, at the upper left as shown in Fig.17, and at the upper right as shown in Fig.18. A third embodiment of the present invention shown in Figs.27 to 29 differs from the first embodiment by the fact that the guard device 4 is replaced with a modified guard device 4E in which an arm 7A comprises a stationary arm 24 fixedly mounted to the fitting ring 6, a movable arm 26 having at its distal end a guard plate 10D, and a pin 25 by which the movable arm 26 is coupled to the distal end of the stationary arm 24 so that it can swing upward and downward about the pin 25. In particular, the stationary arm 24 and the movable arm 26 have sets of serrations 27 and 28 respectively provided on the corresponding surfaces thereof and are coupled to each other by a considerable strength of the pin 25. Accordingly, the movable arm 26 remains stationary at an angle, or linear, to the stationary arm 24 in a normal state and can pivotably be moved about the pin 25 by an outside force. A dental tool 11E provided with the guard device 4E having the arm 7A can be used with the guard plate 10D arranged at a desired vertical position. A fourth embodiment of the present invention shown in Figs.30 and 31 differs from the first embodiment by the fact that the guard device 4 is replaced with a modified guard device 4F in which an arm 7B comprises a stationary arm 24A fixedly mounted to the fitting ring 6, a movable arm 26A having at its distal end a guard plate 10D, and a screw 25A threaded through a hole of the movable arm 26A into a female thread 25a provided in the distal end of the stationary arm 24A so that the movable arm 26A can swing leftward and rightward about the screw 25A. Accordingly, a dental tool 11F provided with the guard device 4F having the arm 7B can be used with the guard plate 10D fastened at a desired horizontal position. A fifth embodiment of the present invention shown in Figs.32 to 35 differs from the first embodiment by the fact that the guard device 4 is replaced with a modified guard device 4G in which an arm 7C is slidably fitted at proximal end into the through hole 32 of an arm support portion 33 of a C-shaped fitting member 6A so that it can stay at a desired position with a retaining screw 34 tightened through a female thread 35 of the arm support portion 33 and has at distal end a guard plate 10D. Accordingly, a dental tool 11G provided with the guard device 4G allows the arm 7C to extend or retract and the guard plate 10D to be rotated with the arm 7C for optimum positioning. In more particular, the arm 7C has a thread hole 38 provided in the distal end thereof into which a guard plate retaining screw 37 is threaded, and a shaft hole 36 provided in the same to communicate with the thread hole 38. The guard plate 10D incorporates a shaft 39 which is fitted into the shaft hole 36 of the arm 7C. The shaft 39 has at centre a recess 40 for accepting the forward end of the guard plate retaining screw 37. A sixth embodiment of the present invention shown in Figs.36 to 38 differs from the fifth embodiment by the fact that the guard device 4G is replaced with a modified guard device 4H in which an arm 7D is adapted foldable to the left or right. Accordingly, a dental tool 11H provided with the guard device 4H allows the arm 7D to extend or retract and turn to left or right, and the guard plate 10D to be rotated with the arm 7D for optimum positioning. A seventh embodiment of the present invention shown in Figs.39 to 41 differs from the sixth embodiment by the fact that the guard device 4H is replaced with a modified guard device 4I in which a guard plate 10E has an L-shaped shaft 39 thereof which is fixedly fitted into the shaft hole 36 of the arm 7D. Accordingly, a dental tool 11I provided with the guard device 4I allows the guard plate 10E to be rotated with the arm 7D and also, moved upward and downward to a desired position. An eighth embodiment of the present invention shown in Figs.46 and 47 differs from the first embodiment by the fact that the guard device 4 is replaced with a modified guard device 4J in which an arm 7E is supported by an arm support 41 provided on the outer surface of a C-shaped fitting member 6B which is made of a synthetic resin material and detachably mounted to the tool body 1. Accordingly, a dental tool 11L provided with the guard device 4J allows the arm 7E to extend or retract and rotate for optimum positioning. A ninth embodiment of the present invention shown in Figs.48 to 50 differs from the first embodiment by the fact that the guard device 4 is replaced with a modified guard device 4K in which the arm 7 has a shaft holder 42 provided integrally on the distal end thereof for holding a shaft 44 of a guard plate 10H which remains urged by a spring 43 in a locking direction. The guard plate 10H is arranged tiltably to a given angle. A dental tool 11M provided with the guard device 4K will be operated with equal success. In particular, the shaft holder 42 of a tubular shape has a plurality of recesses 45 in the lower opening end wall thereof. Also, a corresponding number of projections 46 are provided on a rib flange of the guard plate shaft 44 for engagement with the recesses 45 of the shaft holder 42. Accordingly, the guard plate shaft 44 can be set at a desired position to the shaft holder 42 by pulling against the yielding force of the spring 43 for disengagement of its projections 46 from the recesses 45 of the shaft holder 42 and after turning to the desired position, allowing the projections 46 to fit back into the recess 45 for locking. A tenth embodiment of the present invention shown in Figs.51 to 53 differs from the sixth embodiment by the fact that the guard device 4H is replaced with a modified guard device 4L in which the foldable arm 7D has at distal end an arcuate guard plate 10I extending to the front side of the cutting bit 3. Accordingly, a dental tool 11N provided with the guard device 4L can be protected from an innermost part of the mouth cavity wall. It would be understood that the foregoing embodiments of the present invention is illustrative and not limitative of the shape of the fitting ring or member, the mounting of the fitting ring or member to the tool body, the coupling between the arm and the fitting ring or member, the construction of the arm, the coupling between the arm and the guard plate, and the shape of the guard described previously. Other changes and modifications will be possible without departing the scope of the present invention. As set forth above, the present invention will ensure the following advantages. (1) The dental power tool of the present invention comprises a tool body to be held by hand, a cutting bit detachably attached to a high-speed rotary head fixedly mounted to the front end of the tool body, and a guard device mounted to the tool body to be adjacent to the cutting bit and having a guard plate for keeping an obstacle, e.g. the tongue or a part of the inside wall of a lip, aside during treatment on a decayed tooth in the mouth. Hence, the dental power tool of the present invention allows a dentist to carry out a dental treatment without the help of a hygienist because its guard device presses away a possible obstacle which exists near the treated tooth. The dental treatment will thus be conducted with efficiency. (2) Due to the arrangement described in the paragraph (1), the dental treatment can be executed by a dentist alone with ease and precision regardless of troublesome cooperation with a hygienist. (3) Due to the arrangement described in the paragraph (1), the guard device which is variable in position to and detachable from the tool body can arbitrarily be adjusted for ease of the dental treatment. (4) Due to the arrangement described in the paragraph (1), the dental treatment can be conducted while giving no discomfort to a patient.

Claims: A dental power tool (11) for treatment of a decayed tooth, comprising: a tool body (1) to be held by the dentist's hand; a high-speed rotary head (2) mounted to the front end of the tool body (1); a cutting bit (3) detachably attached to the rotary head; and a guard device (4) including a guard plate (10) adjacent to the cutting bit (3) for keeping aside a possible obstacle, such as the tongue (5a) or a part of the inside wall of a lip, during the dental treatment; characterised in that the guard plate (10) is mounted on the front end portion of an elongate arm (7) which extends along the dental power tool, the rear end portion of the arm (7) being mounted on a fitting ring (6) which is mounted on a proximal portion of the tool body (1), thereby leaving the distal portion of the tool body (1) free to be gripped by the dentist's hand which can at the same time manipulate the guard device (4). A dental power tool as claimed in claim 1, in which the fitting ring (6) is movably mounted on the tool body (1). A dental power tool as claimed in claim 2, in which the proximal portion of the tool body (1) is tapered and the fitting ring (6) is slidably fitted on the tapered proximal portion. A dental power tool as claimed in any preceding claim, in which the front end portion of the arm (7A;7B;7D) is swingable relative to the rear end portion. A dental power tool as claimed in any preceding claim, in which the guard plate (10D) is movably mounted on the arm (7C;7D). A dental power tool as claimed in any preceding claim, in which the rear end portion of the arm (7C;7D) is movably mounted on the fitting ring (6A).

Inventors: NAKAMURA SHOUKOU, NAKAMURA, SHOUKOU
Applicants: NAKAMURA SHOKO, NAKAMURA, SHOUKOU
Application year: 1992
Main classification: A61C1
IPC codes: A61C1, A61C5