Dentistry – Prosthodontics – Dental implant construction
Reexamination Certificate
1999-06-11
2001-08-28
Manahan, Todd E. (Department: 3732)
Dentistry
Prosthodontics
Dental implant construction
Reexamination Certificate
active
06280195
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to a method of treating a patient having a toothless site in a jaw.
BACKGROUND OF THE INVENTION
The replacement of one or more lost natural teeth may be achieved by anchoring a dental implant to the jaw bone at the toothless site. A dental implant is typically defined by (i) one or more fixtures anchored in the jaw bone at the toothless site beneath the overlying gingival layer, the number of fixtures used depending on whether the dental implant is to be for a single-tooth replacement, in which case a single fixture is used, or for replacement of a number of lost teeth, in which case at least one fixture will be used (ordinarily a plurality of spaced-apart fixtures), and (ii) an abutment secured to each fixture through an opening provided in the gingival layer, the structure of the abutment which is disposed above the coronal end of the associated fixture projecting from the coronal margin of the gingival layer at the opening (hereinafter the “transgingival structure”). A structure which presents one or more artificial crowns (hereinafter a “crown structure”) is then connected to the abutment(s).
Abutments in the main are presently prefabricated as standardised ready-to-use components, coming in a set for the clinician to choose from. The prevailing conditions in the oral cavity, however, differ from patient to patient. Accordingly, standard abutments have the drawbacks of not being customised.
With this in mind, prior U.S. Pat. No. 5,316,477 makes known a customisable abutment having a frusto-conical transgingival structure in which the larger end is spaced furthest from the coronal end of the fixture. The frusto-conical profile of the transgingival structure enables the mass of the transgingival structure to be reduced to create the desired profile for a specific patient.
It is an aim of the present invention to provide an improved customised dental implant and method for forming said implant.
BRIEF DESCRIPTION OF THE INVENTION
According to the present invention there is provided a method of treating a patient having a toothless site in a jaw comprising the step of:
(a) providing a fixture for anchorage in the bone of the jaw at the toothless site having a coronal end,
(b) anchoring the fixture in the bone such that the coronal end is submerged beneath the coronal margin of the gingival layer at the toothless site,
(c) providing an abutment which is securable in an operational position to the fixture through an opening provided through the gingival layer to the fixture, the abutment having a transgingival structure which comprises an apical section which tapers outwardly from an apical end of the transgingival structure which in the operational position of the abutment is co-planar with the coronal end of the fixture to a position at which the transgingival structure has maximum transverse dimension and a coronal section contiguous with the apical section which tapers inwardly from the maximum transverse dimension to a coronal end of the transgingival structure, the apical section terminating at the position of maximum transverse dimension with a convex outer surface profile,
(d) removing material from the transgingival structure so as to form a peripheral shoulder of a profile which closely follows that of the coronal margin of the gingival layer at said opening, and
(e) forming a crown structure which seats on the peripheral shoulder when the abutment is secured to the fixture.
In an embodiment of the invention the position of maximum transverse dimension is the junction of the convex outer surface profile of the apical section with the coronal section.
In an embodiment of the invention the coronal section of the transgingival structure of the abutment has a frusto-conical outer surface profile between the position of maximum transverse dimension and the coronal end. The transgingival structure may instead have a stepped outer surface profile between the position of maximum transverse dimension and the coronal end.
In an embodiment of the invention the apical section has a tulip-shape with a stem in-between the apical end and the convex outer surface profile. The stem may have a concave outer surface profile.
In an embodiment of the invention the abutment is formed from a biocompatible material, for example a metal such as titanium.
In an embodiment of the invention the maximum transverse dimension of the transgingival structure is greater than the transverse dimension of the coronal end of the fixture. In fact, the maximum transverse dimension of the transgingival structure may be greater than the maximum transverse dimension of the fixture if this is not presented by the coronal end of the fixture.
In an embodiment of the invention the abutment is screw retained to the fixture. For instance, the abutment may have a stepped screw passage through which a screw can be threaded into an internally threaded bore in the coronal end of the fixture bringing a head of the screw into abutment with the step in the screw passage thereby locking the abutment to the fixture.
In an embodiment of the invention the crown structure is cemented to the abutment. To this end, the method of the invention may further comprise the steps of applying a removable spacer to a section of the transgingival structure which extends from a position disposed coronally of the peripheral shoulder to the coronal end, building up the crown structure from the transgingival structure with the removable spacer thereon, removing the spacer so that when the crown structure seats on the peripheral shoulder of the abutment there is an annular space between the crown structure and the section of the transgingival structure for cement to be disposed for cementing the crown structure to the abutment.
In an embodiment of the invention the peripheral shoulder is so formed on the transgingival structure of the abutment that when the abutment is secured to the fixture the buccal aspect of the peripheral shoulder is disposed intragingivally and the lingual aspect is disposed supragingivally. Having the buccal aspect disposed intragingivally gives improved aesthetics whereas having the lingual aspect of the peripheral shoulder disposed supragingivally is particularly useful where the crown structure is cemented to the abutment as it enables the clinician to get sufficient purchase on the crown structure to remove it from the abutment.
In an embodiment of the invention the toothless site is a single-tooth site and the crown structure presents a single-tooth crown.
In an embodiment of the invention the toothless site is a multiple-tooth site and the method comprises the steps of anchoring a number of the fixtures in the jaw at the toothless site beneath the coronal margin of the gingival layer, providing a number of the abutments which corresponds to that of the fixtures for securement to the fixtures through openings provided through the gingival layer to each fixture, removing material from the transgingival structure of each abutment so as to form a peripheral shoulder on each abutment of profile which closely follows that of the coronal margin of the gingival layer at the opening to the associated fixture and forming the crown structure such that it bridges the abutments when secured to the fixtures and presents a range of single-tooth crowns. The crown structure in this embodiments may be a full or partial bridge or overdenture.
In an embodiment of the invention the or each abutment is selected from a set of standards abutments having different maximum transverse dimensions.
In an embodiment of the invention the or each fixture has a socket in the coronal end thereof and the or each abutment has a complementary plug structure disposed apically of the transgingival structure.
By way of example, preferred embodiments of the invention will now be described with reference to the accompanying Figures of drawings.
REFERENCES:
patent: 4180910 (1980-01-01), Straumann et al.
patent: 4447209 (1984-05-01), Sutter
patent: 4484570 (1984-11-01), Sutter et al.
patent: 4758161 (1988
Bergstrom Nils Gustaf
Broberg Leif
Holmen Anders
Astra Aktiebolag
Manahan Todd #E.
White & Case LLP
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