Dentistry – Apparatus – Having intra-oral dispensing means
Reexamination Certificate
1999-11-30
2001-02-06
Wilson, John J. (Department: 3732)
Dentistry
Apparatus
Having intra-oral dispensing means
C433S127000
Reexamination Certificate
active
06183252
ABSTRACT:
BACKGROUND OF THE INVENTION
1
. Field of the Invention
The invention relates to a dental syringe for dentists, especially to a dental syringe of which the nozzle can be easily fitted and removed, and a nozzle-holding means with which the glove or even the fingertip of the dentist will not be liable to be pinched.
2. Description of Related Art
Dentists often use a drill to grind and clean the cavities in teeth, and use a dental syringe, containing either water or gas, to flush or blow away the bits produced by the drilling.
Shown in
FIGS. 5 and 6
is a conventional dental syringe (
2
) for dentists, consisting of a head (
21
), a handle (
22
), a holding device (
23
), and a nozzle (
24
). The nozzle (
24
) includes a first end, and a second end with a circumferential under cut defined near thereto. The nozzle (
24
) has a major diameter and the under cut has a minor diameter. The head (
21
) has a male thread (
211
) thereunder used to engage with a female thread (
221
) defined in the top of the handle (
22
). In use, the first end of the nozzle (
24
) can be inserted in a patient's mouth to align with a cavity needed to be flushed. For reasons of hygiene, the nozzle (
24
) must be changed usually at least once for each patient. The second end of the nozzle (
24
) is affixed to the head (
21
) by means of the holding device (
23
) received in an opening (
212
) defined in the front of the head (
21
). The holding device (
23
) includes a pipe (
231
) having a male thread for engaging with a female thread defined in the opening (
212
), a small barrel (
232
) covering and being slidable along the pipe (
231
), and a spring (
233
) being pressed between a bottom of the barrel (
232
) and a bottom of the opening (
212
). In a non-retracted mode of the dental syringe, the barrel (
232
) is pushed away from the head (
21
) by the spring (
233
) and covers a plurality of balls disposed in the pipe (
232
) thus pressing them radiallyinward to a first position. The balls in the first position describe a diameter that is equal to the minor diameter but smaller than the major diameter of the nozzle (
24
) and thus the second end of the nozzle (
24
) cannot enter the head (
21
). When the nozzle (
24
) is to be inserted in the head (
21
), a dentist must pull the barrel (
232
) backward against the spring (
233
) whereafter the balls are free to move to a second position where they describe a diameter greater than the major diameter of the nozzle (
24
), such that the second end thereof can enter the head (
21
). Then the dentist releases the barrel (
232
) which is accordingly pushed back to its original position of the non-retracted mode, thereby urging the balls radially inward to be received in the under cut, whereby the nozzle (
24
) is securely retained in the head (
21
). Reversal of the above process enables the nozzle (
24
) to be removed from the head (
21
). From the above description, the conventional dental syringe for dentists has following shortcomings:
1. in both assembly and removal , dentists have to simultaneously grasp the nozzle (
24
), hold the handle (
22
), and push the barrel (
232
) which requires considerable dexterity.
2. after releasing the barrel back, a glove or even a hand of the dentist is often pinched between the pipe (
24
) and the barrel (
232
).
REFERENCES:
patent: 3393676 (1968-07-01), Kummer et al.
patent: 5125835 (1992-06-01), Young
patent: 5306146 (1994-04-01), Davis et al.
patent: 5433485 (1995-07-01), Austin, Jr. et al.
patent: 5490683 (1996-02-01), Mickel et al.
Pelton, Esq. William E.
Wilson John J.
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