Dentistry – Apparatus – Tool bit
Reexamination Certificate
2001-01-30
2002-07-16
Wilson, John J. (Department: 3732)
Dentistry
Apparatus
Tool bit
C606S080000
Reexamination Certificate
active
06419490
ABSTRACT:
This application relates to the field of medicine, and more specifically involves corrective measures to improve the success of intraosseous medication injections in Dentistry and related fields requiring anaesthesia.
DISCUSSION OF THE PRIOR ART
The art of deadening pain for the Dental industry was greatly improved by the discovery that smaller and more effective dosages of medication could be introduced beneath the cortical plate. Pivotally, U.S. Pat. No. 5,173,050 by Dillon in 1992 cited methods of and implements for drilling an initial perforation, thus allowing the dentist to remove the drill bit and re-enter the passageway with a hypodermic needle to deliver anaesthesia.
However, difficulties as taught by Dillon mainly involving failures of re-entry caused the industry to respond with two U.S. patents: U.S. Pat. No. 5,762,639 by Gibbs, and U.S. Pat. No. 5,779,708 by Wu, both describing methods to leave an intra-osseous hollow channel in place subsequent to drilling. This hollow channel served as a guidance system to allow re-entry for medicative purposes.
Adversely, the necessity of hollow guidance sleeves to themselves be drill bits increased the expense over Dillon and introduced dangers involving incidents of breakage of the tiny-diameter, hollow implements. The threat of the breakage and subsequent successful retrieval of all foreign objects from the patient is complicated by the presence as taught by Gibbs and Wu of other separate and intricate inner plugging stylets or rods. These latter implements strengthen the overall shaft and block the backflow of bone chips and other organic matter while drilling.
As a further response of the prior art, U.S. Pat. No. 6,135,769 by Kwan teaches a hollow drill bit with a side hole located a short distance up the drill shaft from the entry tip. The claimed advantage over Gibbs and Wu being no inner stylet is required, which reduces manufacturing costs. Also the step of removing the inner stylet after drilling is deleted.
A pertinent negative to the Kwan patent is the fact breakage of the drill bit is enhanced by two considerations:
1. Without the inner stylet of both Gibbs and Wu the overall strength of the Kwan drill bit is less in comparison.
2. The introduction of a hole through the hollow circular walls of the drill bit itself creates a hot-spot location that by its physical nature is weaker to torque stress than non-perforated positions along the drill bit. If breakage occurs, the likelihood is increased that the broken tip section will be unretrievable short of surgery. This is because the perforated section must advance to a functional depth such that it clears the inner wall of the hard bone to reach into the interior soft cancellous bone tissue.
Another pertinent negative for all patents utilizing channeled drills is the possible undesirable introduction of bacteria into the underlying tissues of the patient. The method of operation requires the drill to be left in the jawbone while dental work goes on, and thus in the process air or water mediums can introduce small but significant levels of living microbes.
OBJECTS AND ADVANTAGES
It is therefore accordingly an object of the present invention to provide a guidance channel through the cortical plate that does not employ a hollow drill bit, thus lessening the risk of breakage.
It is further accordingly an object of the present invention to provide a guidance channel through the cortical plate that lessens discomfort by offering the higher penetrative speed that a true solid drilling tip delivers.
It is further accordingly an object of the present invention to provide a guidance channel through the cortical plate of small manufacturing cost.
It is further accordingly an object of the present invention to provide a guidance channel through the cortical plate with a minimalized list of procedural steps for the Dentist.
It is further accordingly an object of the present invention to provide a guidance channel through the cortical plate that reduces the introduction of airborne or waterborne bacteria to the inner tissues while the drill is left in place.
These and many other objects and advantages will be readily apparent to one skilled in the art to which the invention pertains from a perusal of the claims and the following detailed description of preferred embodiments when read in conjunction with the appended drawings.
NATURE OF THE INVENTION
A solid drill bit can bear a functional groove or canyon along its shank reaching far enough down the overall length to allow the delivery of anaesthesia while the drill bit remains inside the bone. The groove is reduced in depth (scalloped) at its delivery end to flex the needle tip and deflect the tip out from the drill bit and into the desired tissue.
In the preferred embodiment a solid steel drill bit is turned at high speed on a lathe while a thin skin of steel is polished off with a diamond tipped abrasive. The resulting drill bit has a uniform circumference all along its shaft to a point near the drilling tip, where no polishing was done. In essence, the drill bit has a head and a long neck, with the neck reduced to a circumference still almost as large as the head itself.
Next a groove is cut along the length of the shaft sufficient to create a guidance channel for a typical drug delivery needle. The end of the groove near the tip is curved along the bottom, and this scalloping allows the depth of the groove to lessen. Before the drill bit is fabricated in an insertion injection molding machine with a plastic hub, a thin sleeve of tubular plastic such as polyethylene or polypropylene is fitted over the polished section of the drill bit. The circumference of the drill bit at the unpolished section is equal to or greater than the circumference of the polyethylene section, thus allowing the drill bit in use to bore and penetrate without stress to the polyethylene layer.
A dental handpiece is a drill that by design has a chuck to grasp either the hub or an adapter linked to the hub of a drill bit. The drill bit can then perforate the cortical plate and be detached from the handpiece. The subsequent removal of the handpiece leaves a funnel opening to the groove exposed for introduction of the liquid deadening agent by the typical drug delivery needle. The curved groove causes the flexible tip of the inserted needle to bend upwards in the groove in such a manner that it first punctures the polyethylene down near the drilling tip and then allows the fluid to be injected into the desired interior region of the jaw.
Although not vital to the design or drug delivery intent of the invention, it should be understood that with careful selection of the polyethylene or other plastic chosen for the covering of the groove, removal of the sterile needle allows the perforated plastic to close back on itself. This effectively stops or reduces the introduction of airborne or waterborne bacteria to the inner tissues while the drill is left in place. The use of a rubbery type carbon compound such as polyethylene is cited because a holistic or shatter proof barrier is desired. This means a rupture of the plastic for passage of the needle tip is facilitated without a detachment of large fragmentary particles of the barrier plastic itself.
REFERENCES:
patent: 5173050 (1992-12-01), Dillon
patent: 5261818 (1993-11-01), Shaw
patent: 5762639 (1998-06-01), Gibbs
patent: 5779708 (1998-07-01), Wu
patent: 5941706 (1999-08-01), Ura
patent: 6135769 (2000-10-01), Kwan
Bumgarner Melba
Wilson John J.
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