US 738929 A
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Z'ZZZ ZZ, I 19304310? i'atented September 15, 1903.
PATENT ()FFICE- ANDREW 'I. MCMILLIN, OF LITTLE ROCK, ARKANSAS.
SPECIFICATION forming part of Letters Patent No. 738,929, dated September 15, 1903.
Application filed June 16, 1903. Serial No. 161,726. (No model.)
To all whom, it may concern:
Be it known that I, ANDREW T. MCMILLIN,
a citizen of the United States, residing at Little Rock, in the county of Pulaski and State of Arkansas, have invented a new and useful Dental Instrument, of which the following is a specification.
The invention relates to certain improvements in dental instruments, and has for its principal object to provide a tool for the removal of crown-pins from natural teeth in the event of breakage or injury to the crown.
In the application of porcelain and other crowns to natural teeth the crown is secured to one end of a wedge-like pin, which is cemented in an opening formed in the natural tooth. In the event of breakage of the crown it becomes necessary to remove the pin, and at the present time this is accomplished by drilling. As the metal: of which the pin is formed is much harder than the tooth surrounding it, the drills will slip and in some cases work directly through the wall of the tooth,makingit necessary to extract the latter. The operation, moreover, takes considerable time and results in considerable inconvenience and pain to the patient.
In carrying out my invention I employ a pin-extracting means, which is first secured to the lower end of the pin, and the latter is then withdrawn by means of ascrew, the operation being quickly accomplished and with little or no inconvenience to either the patient or operator.
In the accompanying drawings, Figure l is a longitudinal sectional elevation of a dental instrument constructed in accordance with the invention, the view being on an enlarged scale in order to more clearly show the construction. Fig. 2 is a detail perspective view of the instrument.
Similar numerals of reference are employed to indicate corresponding parts in both figures of the drawings.
In the drawings, 1 indicates a cylindrical body,which in practice will be one inch, more or less, in length, the lower portion of said cylinder being of reduced diameter and provided with an internal screw-thread adapted to receive an elongated threaded spindle 2, at the lower end of which is a bar or turningvto firmly secure the two together.
knob 3. To the lower end of the spindle is loosely swiveled a head 5 of a diameter less than the internal diameter of the upper portion of said cylinder, so that it may be withdrawn into the latter by turning the bar or knob in the proper direction.
The head 5 is provided with a vertical loop 8, which is coupled to the lower portion of the crown-pin by first drillinga small hole in the lower part of the pin and then coiling fine wire through the hole and the loop in order As the pin will in'all cases project somewhat above the top of the tooth or root, the opening may be readily made by the use of an ordinary form of bur and the Wire quickly attached and its ends twisted in such manner as to firmly unite the pin and loop. The bar or knob 3 is then turned until the upper end of the cylinder bears against the surface of the tooth at a point outside the pin, and on continuing the turning operation the head will be gradually raised and the pin withdrawn, while the swiveled connection between the screw and head will prevent turning movement ofthe pin and injury to the tooth. The withdrawing operation is facilitated by the entrance of the head into the hollow cylinder, the latter serving as a guard for the head and preventing lateral strain, so that the pin must be withdrawn in the direction of its length.
With an instrument constructed in accord-. ance with this invention a crown-pin maybe quickly removed without injury to the patient and without the expenditure of any considerable time and labor on the part of the operator.
Having thus described the invention, what I claimis- 1. In a pin-extracting device, means for engaging the pin, and a supporting means adapted to bear on the surface of the tooth.
2. In a pin-extracting device, a threaded support adapted to bear on the surface of a tooth, a screw carried by the support, and
carried by the screw and serving as a pinconnecting means.
4. In a pin-extracting device, a cylinder having an outer portion provided with a thread, a threaded spindle therein and provided at one end with an operating-bar, and a swiveled head disposed at the opposite end of the screw and having a vertical loop, said head being guided Within the open inner end of said cylinder during the extraetingopera- IO tion.
In testimony that I claim the foregoing as my own I have hereto affixed my signature in the presence of two witnesses.
v A. l. MOMILLIN. Witnesses:
JOHN B. BOND, Sr., WILL C. BOND.