US4904185A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Dental instrument
Assignee: MUFG Union Bank NA
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Filing: 1988-11-04
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Granted: 1990-02-27
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Expires: 2008-11-04
Abstract
Abstract In one embodiment, a condenser instrument for thermomechanically condensing a thermoplastic material, such as gutta percha, in the extirpated root canal of a tooth through rotation of the instrument is disclosed. The condenser instrument includes a shank having a tapered working portion along part of its length. The working portion includes a single, continuous helical flute defining a continuously helical shoulder having a negative rake angle. The shoulder is generally directed downwardly toward the tip end of the shank. A wide land is formed at the periphery of the shoulder. In a second embodiment, a remover instrument for removing a thermoplastic material, such as gutta percha, from a previously obturated root canal of a tooth through rotation of the remover instrument is disclosed. The remover instrument includes a shank having a tapered working portion along part of its length. The working portion includes a single, continuous helical flute defining a continuous helical shoulder having a negative rake angle. The shoulder is generally directed upwardly away from the tip of the shank. A wide land is formed at the periphery of the shoulder.
Inventors
- 👤 John T. McSpadden
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 07:49
CPC Classifications
A; A61; A61C; A61C5/00; A61C5/40; A61C5/42
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
171 words
An instrument for use with a dental hand piece for thermomechanically obturating a root canal with a thermoplastic material by a process wherein the thermoplastic material is softened by the friction executed by the rotation of the instrument, said instrument comprising an elongated member having a shank at one end thereof which includes a fitting for engagement with a dental hand piece, a tapered working portion at the other end of said member, the diameter of said working portion progressively decreasing away from said shank portion, flute means on said working portion defining a spiral flute having a shoulder facing away from said shank and making an angle with the longitudinal axis of the working portion of greater than 90 degrees to provide a negative rake angle as said instrument is rotated to advance thermoplastic material towards the end of said working portion remote from said shank and a peripheral land adjacent said shoulder having a width which is at least about 40 percent of the pitch of said spiral flute.
Claim 2
Dependent Claim
171 words
An instrument for use with a dental hand piece for thermomechanically obturating a root canal with a thermoplastic material by a process wherein the thermoplastic material is softened by the friction executed by the rotation of the instrument, said instrument comprising an elongated member having a shank at one end thereof which includes a fitting for engagement with a dental hand piece, a tapered working portion at the other end of said member, the diameter of said working portion progressively decreasing away from said shank portion, flute means on said working portion defining a spiral flute having a shoulder facing away from said shank and making an angle with the longitudinal axis of the working portion of greater than 90 degrees to provide a negative rake angle as said instrument is rotated to advance thermoplastic material towards the end of said working portion remote from said shank and a peripheral land adjacent said shoulder having a width which is at least about 40 percent of the pitch of said spiral flute.
Claim 3
Dependent Claim
23 words
The instrument of claim 1 wherein the width of said peripheral land is about 50 percent of the pitch of said spiral flute.
Claim 4
Dependent Claim
45 words
The instrument of claims 1 or 2 wherein the number of shoulders appearing on a side of the working portion of said instrument over a 16 mm length vary from about 12 for a size 25 instrument to about 5 for a size 140 instrument.
Claim 5
Dependent Claim
167 words
An instrument for use with a dental hand piece for thermomechanically removing thermoplastic material from an obturated root canal by a process wherein the thermoplastic material is softened by the friction executed by the rotation of the instrument, said instrument comprising an elongated member having a shank at one end thereof which includes a fitting for engagement with a dental hand piece, a tapered working portion at the other end of said member, the diameter of said working portion progressively decreasing away from said shank portion, flute means on said working portion defining a spiral flute having a shoulder facing away from said shank and making an angle with the longitudinal axis of the working portion of less than 90 degrees to provide a negative rake angle as said instrument is rotated to advance thermoplastic material along said working portion toward said shank and a peripheral land adjacent said shoulder having a width which is at least about 40 percent of the pitch of said spiral flute.
Claim 6
Dependent Claim
167 words
An instrument for use with a dental hand piece for thermomechanically removing thermoplastic material from an obturated root canal by a process wherein the thermoplastic material is softened by the friction executed by the rotation of the instrument, said instrument comprising an elongated member having a shank at one end thereof which includes a fitting for engagement with a dental hand piece, a tapered working portion at the other end of said member, the diameter of said working portion progressively decreasing away from said shank portion, flute means on said working portion defining a spiral flute having a shoulder facing away from said shank and making an angle with the longitudinal axis of the working portion of less than 90 degrees to provide a negative rake angle as said instrument is rotated to advance thermoplastic material along said working portion toward said shank and a peripheral land adjacent said shoulder having a width which is at least about 40 percent of the pitch of said spiral flute.
Claim 7
Dependent Claim
23 words
The instrument of claim 4 wherein the width of said peripheral land is about 50 percent of the pitch of said spiral flute.
Claim 8
Dependent Claim
45 words
The instrument of claims 4 or 5 wherein the number of shoulders appearing on a side of the working portion of said instrument over a 16 mm length vary from about 12 for a size 25 instrument to about 5 for a size 140 instrument.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1993-02-26 | 1993-08-28 | 1994-02-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-02-26 | 1997-08-28 | 1998-02-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-02-26 | 2001-08-28 | 2002-02-27 | $7700.00 | Window Closed / Lapsed |