Dentistry – Apparatus – Having motor or means to transmit motion from motor to tool
Reexamination Certificate
2000-10-24
2001-10-23
Lucchesi, Nicholas D. (Department: 3732)
Dentistry
Apparatus
Having motor or means to transmit motion from motor to tool
C433S127000, C433S128000
Reexamination Certificate
active
06305935
ABSTRACT:
BACKGROUND OF THE INVENTION
My U.S. Pat. No. 6,099,309, relates generally to a disposable prophy angle. Structure of this prophy angle is utilized to contain and support the present invention.
1. Field of the Invention
The present invention relates generally to an improved disposable contra-angle. More particularly, the present invention relates to disposable burs that can be placed into rotation for high speed drive.
2. Description of the Prior Art
Dental drill burs are well known in the art. At present, they are removably placed into the contra-angle by the dentist or the dental assistant. The standard procedure is for the dentist to place the bur into the contra-angle, and after the procedure it is removed manually to be brushed and sterilized. Often, it is discarded because of wear or inability to properly clean. Because the contra-angle is subject to contamination and infection from saliva and blood of the patient, it needs to be brushed; placed into ultrasonic; sterilized; and then lubricated before it can be used again. The lubrication is very critical due to the variable speeds generated by contra-angles. Extra care must be taken to prevent any oil from escaping into the patient's mouth or on the cavity itself. Occasionally the contra-angle must be taken apart because the gears have smudge accumulation and thereby have difficulty operating. This along with normal cleaning creates a substantial time loss leading to lower productivity of the entire dental office. All of this makes the use of reasonably priced contra-angles very practical. But beyond cost, the most important reason for using disposable contra-angles is to reduce the danger from incomplete sterilization, whereby the bacteria and infection are then transferred from one patient to another.
The main problems associated with the prior art is that the retained bur has a tendency to rattle and be generally noisy. This is primarily due to the fact that they are only connected at the superior end. There definitely is too much play between the cylinder of the bur and the core of the rotating mandrel. This results in energy loss, fatigue, loss of cutting efficiency. The patients feel all of this, and thus there can be an increase in anxiety in an already very stressful environment.
U.S. Pat. No. 5,766,008 issued to Hughes on Jun. 16, 1998, teaches what is the standard method of inserting a dental bit into the dental handpiece. One end of the shank's superior end being luted.
U.S. Pat. No. 5,749,728 issued to Bailey on May 12, 1998, teaches the use of a disposable dental angle. He uses a latch on the cap to lock the angle together. This latch is typical of the method employed in the prior art to contain the driving and driven gears and to retain a bur that is held therein.
U.S. Pat. No. 5,718,582 issued to Quinn et al. on Feb. 17, 1998, is illustrative of a patent that has a solution for the one of the most common problem encountered in dental handpieces, especially those that reach speeds of 400,000 rpm. This problem is rotation and axial slippage within the mandrel (chuck).
None of the above inventions and patents, either singly or in combination, is seen to describe the instant invention as claimed.
SUMMARY OF THE INVENTION
Accordingly, the above problems and difficulties are obviated by the present invention which provides for a disposable contra-angle to be used in association with motorized dental handpieces.
More particularly, the present invention is comprised of four major sections: a sleeve, a neck, a head and a bur attachment. The main inventive concept of the present invention being the utilization of a gear system at a relative distance from the head. This gear ratio taking place in the sleeve section, which has the largest cross sectional area. A secondary shaft, leading from the location of the gear ratio, needs to be only a fraction of the size of the main drive shaft. This allows the neck section to be thinner, thereby allowing greater visibility for the dentist. Also, by having the gear ratio take place in the sleeve section, the heaviest portion of the contra-angle is in the handle. This will create a more balanced contra-angle, one that will be easier for the dentist to control, cause less fatigue, give better access, and it will also help to keep the hands of the dentist out of and away from the patient's mouth.
The working member of the contra-angle is a bur which differs from the prior art in that it is disposable and has a new and improved means for retention within the head of the contra-angle. The present invention allows for the bur to be either placed manually by the dentist or by the manufacturer. The manufacturer would use a luting process and the bur and contra-angle would be disposed of together. The advantage of having the dentist place the bur is that it would be possible, in cases of improved materials, for the dentist to only remove the bur and thereby reuse the contra-angle a plurality of times.
Two primary considerations in designing a contra-angle system is the retention of the bur without rotation or slippage. Also the ability of the angle to deliver true spin to the working bur. Most systems today use a manually extending latch to retain the bur within the housing. The per cost of most of the burs used today is approximately $1.00. The time required to sterilize and lubricate is far in excess of that cost. Also to brush the flutes and cross cut patterns of a bur is not economical. Therefore, it is aim of the present invention to have a disposable unit.
The present invention provides a redesign of the bur shaft and the seating area within the mandrel to provide for the disposability of the bur and/or contra-angle. The aim of the present invention is to have superior retentive characteristics. Also the majority of the parts for the contra-angle can be manufactured out of plastic materials. Most prior art burs are made from a highly polished circular rod having a flat section and a circular notch for the manual latch means. The flat surface is for rotation of the bur more so than the latch. The latch is strictly a retentive feature.
The present invention utilizes a more extensive flat slot along the longitudinal suface of the bur shaft and abuts the inner chamber of the mandrel. This extension of the flat slot will resolve the problem created by too much play between bur and cylinder.
The flat side of the bur shaft is luted to a flat surface in the chamber. This aids in retention, rotation, less wobble, less noise and greater efficiency. With the present invention, the rotation of the bur will be equal to the rotation of the mandrel, thereby causing less fatigue to the hands of the dentist, less pressure, less energy expenditure, more efficiency, less friction, less heat and subsequently more comfort for the patient.
Although the present inventon can utilize the conventional latch retention system, their failure due to inadvertent opening due to vibration has prompted the present invention to replace the external manual latch with an internal “O” ring that is contained within a recess area of the contra-angle shell. The top end of the chamber having a circular depression about its entire circumference which corresponds to the “O” ring within the recess. Within the mandrel chamber are a plurality of semi-circular protrusions which are in a cooperating relationship to a plurality of semi-circular grooves disposed in the outer surface of the bur shaft. These “O” rings and protrusions could be metal or hard plastic. Hard plastic would have more give and allow an easier insertion of the bur. An alternate embodiment to the concentric bur shaft would be to have a shaft made in in a triangular, rectangular, hexagonal or some other non-rounded shape. This would increase the rotational retention towards the idealistic 1:1 rotation.
The present invention will provide a cover over an outer boss that in itself rotates at a variable speed. This cover would be a safety feature. It being a circular piece that would either snap into place or else have means for screwing into place
Burns D. Michael
Lucchesi Nicholas D.
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