PROSTHETIC TOOTH OR DENTURE BASE

Abstract

A prosthetic tooth for a denture comprises a lingual or palatal surface, an opposing vestibular surface, opposing proximal surfaces, an incisal or occlusal surface and an opposing apical surface, wherein at least one projection extends from a surface of the tooth for spacing the surface adjacent to the projection from a denture base. Alternatively, a denture base for a denture comprises a space having a surface for receiving a tooth, wherein at least one projection extends from a surface of the denture base for spacing the surface adjacent to the projection from the tooth. The projections assist with providing a substantially uniform or even layer of sufficient adhesive between a tooth and a denture base so that the strength of the bond between the tooth and the denture base is improved. In addition, a projection extending from a surface of a tooth makes it easier to determine whether the tooth is positioned correctly when the tooth is aligned with a denture base.

Claims

1. A prosthetic tooth for a denture, wherein the tooth comprises a lingual or palatal surface, an opposing vestibular surface, opposing proximal surfaces, an incisal or occlusal surface and an opposing apical surface, wherein at least one projection extends from a surface of the tooth for spacing the surface adjacent to the projection from a denture base.

2. A prosthetic tooth according to claim 1, wherein the projection extends from the apical and /or the palatal or lingual surface of the tooth.

3. A denture base for a denture, wherein the denture base comprises a space having a surface for receiving a tooth, wherein at least one projection extends from a surface of the denture base for spacing the surface adjacent to the projection from the tooth.

4. A prosthetic tooth according to claim 1, (i) wherein a plurality of projections extend from the surface of the tooth; (ii) wherein three or four projections extend from the surface of the tooth.

5. (canceled)

6. A prosthetic tooth according to claim 1, wherein each projection extends about 40 .Math.m to about 500 .Math.m from the surface of the tooth.

7. A prosthetic tooth according to claim 1, wherein each projection extends about 100 .Math.m to about 200 .Math.m from the surface, or about 120 .Math.m from the surface.

8. (canceled)

9. A prosthetic tooth according to claim 1, wherein each projection has a base adjoining the surface of a toothand the base of the projection has an area of about 0.2 mm.sup.2 to about 6 mm\.sup.2.

10. A prosthetic tooth according to claim 1, wherein one or more projections are semi spherical, frusto spherical or are defined by the shape of a dome or spherical segment.

11. A prosthetic tooth according to claim 1 , wherein one or more projections are cylindrical.

12. A prosthetic tooth according to claim 1 , wherein the end of the projection distant from the base of the projection is semi spherical, frusto spherical or is defined by the shape of a dome or spherical segment.

13. A prosthetic tooth according to claim 1, wherein one or more projections are cuboid, or defined by a square or rectangular frusto pyramid.

14. A prosthetic tooth according to claim 1 , wherein a plurality of projections having the same or different three dimensional shapes is provided.

15. A prosthetic tooth according to claim 14, wherein each projection is spaced apart from adjacent projections so that, in use, adjacent to the projections, the surface of the tooth is uniformly or evenly spaced from the surface of a denture base.

16. A set of teeth comprising a plurality of teeth according to claim 1.

17. The set of teeth according to claim 16, wherein the set of teeth comprises one or more upper (maxillary) and / or lower (mandibular) teeth.

18. The set of teeth according to claim 16, wherein the set of teeth comprises one or more of central, lateral, cuspid, first bicuspid, second bicuspid, first molar and second molar teeth.

19. A denture comprising a prosthetic tooth according to claim 1.

20. A method for manufacturing a tooth of claim 1, which comprises the step of moulding a tooth having at least one projection extending from the surface of the tooth; or milling a tooth so that at least one projection extends from the surface of the tooth; or three dimensional printing a tooth having at least one projection extending from the surface of the tooth.

21. A method for manufacturing a denture base of claim 3, which comprises the step of moulding a denture base having a surface for receiving a tooth and at least one projection extending from a surface of the denture base for spacing the surface adjacent to the projection from the tooth; milling a denture base so that it has a surface for receiving a tooth and at least one projection extending from a surface of the denture base for spacing the surface adjacent to the projection from the tooth; or three dimensional printing a denture base having a surface for receiving a tooth and at least one projection extending from a surface of the denture base for spacing the surface adjacent to the projection from the tooth.

22. A method for correctly positioning and bonding teeth in a denture which comprises (a) providing one or more teeth of claim 1 and a denture base and bonding the teeth with the denture base.

Description

BRIEF DESCRIPTION OF THE FIGURES

[0040] The invention will now be described with reference to the accompanying drawings, in which:

[0041] FIG. 1 shows a view of an embodiment of a tooth of the invention. The tooth has a projection defined by a rectangular frusto pyramid and four projections defined by spherical segments for spacing the tooth from a denture base.

[0042] FIG. 2 shows a further embodiment of a tooth of the invention. The tooth has a projection defined by a rectangular frusto pyramid and four projections defined by spherical segments for spacing the tooth from a denture base.

[0043] FIG. 3 shows a further embodiment of a tooth of the invention. The tooth has a projection defined by a rectangular frusto pyramid and four projections defined by spherical segments for spacing the tooth from a denture base.

[0044] FIG. 4 shows a further embodiment of a tooth of the invention. The tooth has a projection defined by a rectangular frusto pyramid and four projections defined by spherical segments for spacing the tooth from a denture base.

[0045] FIG. 5 shows a further embodiment of a tooth of the invention. The tooth has three projections for spacing the tooth from a denture base.

[0046] FIG. 6 shows a further embodiment of a tooth of the invention. The tooth has three projections for spacing the tooth from a denture base.

[0047] FIG. 7 shows a plan view of an embodiment of a denture base according to the invention.

[0048] FIG. 8 shows a perspective view of an embodiment of the denture base shown in FIG. 5.

[0049] FIG. 9 shows a front perspective view of an embodiment of the denture base shown in FIGS. 7 and 8.

[0050] FIG. 10 shows an outline in wax of the surfaces of six upper anterior teeth having no projections as described in the comparative tests carried out in the Examples.

[0051] FIG. 11 shows three teeth having no projections placed onto one half of a denture base analogue and three teeth having projections placed on the other half as described in the comparative tests carried out in the Examples.

[0052] FIG. 12 shows a matrix of the vestibular surfaces of six upper anterior teeth as described in the comparative tests carried out in the Examples.

[0053] FIG. 13 shows a denture base analogue pressed onto teeth until initial set had taken place as described in the comparative tests carried out in the Examples.

[0054] FIG. 14 shows the results of comparative experimental tests as described in the Examples. It can be seen that the presence of projections for spacing the teeth from the denture base resulted in the teeth being extensively broken within the teeth themselves, whereas in comparison, when no projections for spacing the teeth from the denture base were present, teeth broke away from the denture base at the bonding surfaces themselves.

DETAILED DESCRIPTION OF THE INVENTION

[0055] The following definitions shall apply throughout the specification and the appended claims.

[0056] The singular forms “a,” “an,” and “the” include plural reference unless the context clearly dictates otherwise.

[0057] Within the context of the present specification, the term “comprises” is taken to mean “includes” or “contains”, i.e. other integers or features may be present, whereas the term “consists of” is taken to mean “consists exclusively of”.

[0058] Within the present specification, the term “about” means preferably plus or minus 20%; more preferably plus or minus 10%; even more preferably plus or minus 5%; most preferably plus or minus 2%.

[0059] Within the present specification, the term “denture” means a prosthetic device constructed to replace missing teeth; a denture consists of a denture base that is supported by the soft and hard tissues of the oral cavity, and artificial denture teeth that restore aesthetics and function for a patient.

[0060] Within the present specification, the term “projection” means an outwardly extending surface, for example a protuberance.

[0061] Within the present specification, the term “apical” refers to the direction towards the base or root(s) or apex(es) of a tooth (the apices), as opposed to coronal, which refers to the direction towards the crown of a tooth.

[0062] Within the present specification, the term “lingual” refers to the side of a tooth which in situ would be adjacent to (or the direction towards) the tongue, as opposed to vestibular which refers to the side of a tooth adjacent to (or the direction towards) the inside of the cheek or lips.

[0063] Within the present specification, the term “palatal” refers to the side of a tooth which in situ would be adjacent to (or the direction towards) the palate, as opposed to vestibular which refers to the side of a tooth adjacent to the inside of the cheek or lips.

[0064] Within the present specification, the term “vestibular” refers to the side of a tooth which in situ would be adjacent to (or the direction towards) the inside of the cheeks or lips, as opposed to lingual or palatal, which refer to the side of a tooth adjacent to (or the direction towards) the tongue or palate, respectively.

[0065] Within the present specification, the term “proximal” refers to the surfaces of teeth that which in situ would be adjacent to another tooth.

[0066] Within the present specification, the term “incisal surface” refers to the biting surface of the anterior teeth i.e. the teeth toward the front of the mouth.

[0067] Within the present specification, the term “occlusal surface” refers to biting surfaces of the posterior teeth i.e. the teeth towards the back of the mouth.

[0068] Unless defined otherwise, all technical and scientific terms used herein have the same meanings as commonly understood by one of ordinary skill in the art.

[0069] Embodiments have been described herein in a concise way. It should be appreciated that features of these embodiments may be variously separated or combined within the invention.

[0070] In a method for production of a denture, each tooth of the denture is inserted into a previously manufactured socket in a denture base having adhesive therein or into which adhesive will be introduced. The adhesive flows around each tooth in the space between the tooth and the denture base and bonds each tooth to the denture base.

[0071] To assist in ensuring that sufficient adhesive is present between each tooth and the denture base, with reference to FIGS. 1 to 6, the invention provides a prosthetic tooth (1) wherein the tooth comprises a lingual or palatal surface (2), an opposing vestibular surface (3), opposing proximal surfaces (4, 5), an incisal or occlusal surface (6) and an opposing apical surface (7), wherein a plurality of dome shaped or rectangular frustopyramid projections (8) extend from the surface of the tooth for spacing the surface (2, 7) from a denture base (9).

[0072] The plurality of projections each extend about 120 .Math.m from the apical surface of the tooth.

[0073] Preferably, each projection has a base adjoining the apical surface of a tooth and the base has an area of about 0.2 mm.sup.2 to about 6 mm.sup.2.

[0074] Each projection is spaced apart from adjacent projections so that, in use, the surface of the tooth adjacent to the projections is evenly spaced from the surface of a denture base.

[0075] The tooth (1) of the invention is manufactured by a method which includes the step of moulding the tooth (1) having one or more projections (8) extending therefrom. Alternatively, the method comprises the steps of milling the tooth (1) so that one or more projections (8) extend from the surface of the tooth (1). Alternatively, the method comprises the steps of three dimensional printing a tooth (1) having one or more projections extending from the surface of the tooth.

[0076] With reference to FIGS. 7, 8 and 9, the invention provides a denture base for a denture, wherein the denture base comprises a space having a surface for receiving a tooth, wherein a plurality of projections (8) extend from the surface for spacing the surface adjacent to the projections (8) from a tooth.

[0077] The plurality of projections (8) each extend about 120 .Math.m from the surface of the denture base.

[0078] Preferably, each projection (8) has a base adjoining the surface of the denture base and the base of the projection (8) has an area of about 0.2 mm.sup.2 to about 6 mm.sup.2.

[0079] Each projection (8) is spaced apart from adjacent projections (8) so that, in use, the surface of the denture base adjacent to the projections is evenly spaced from the surface of a tooth.

[0080] Advantageously the projections (8) facilitate precise positioning of the teeth (1) on the denture base because the projections (8) form stops separating the surface of the teeth (1) from the denture base (9). The back teeth (1) shown in FIG. 5 or FIG. 6 demonstrate how the projections (8) form a tripod which distances the surface of the tooth adjacent the tripod from a denture base (9). The front teeth (1) shown in FIGS. 1 to 4 demonstrate how when there are five projections (8) these can provide five feet to give precise positioning not just in a vertical dimension but also in a horizontal dimension as well. Without this novel invention the surface of the teeth themselves must rest in the adhesive layer between teeth (1) and denture base (9) and the teeth may tilt depending on where pressure is applied when inserting the teeth (1) into the denture base (9).

[0081] When the projections (8) extend from the denture base (9) as shown in FIGS. 7, 8 and 9 the same precise positioning of the teeth (1) into the denture base (9) is obtained.

[0082] The denture base is manufactured by a method which comprises the step of moulding a denture base having a surface for receiving a tooth and at least one projection extending from the surface for spacing the surface adjacent to the projection from the tooth. Alternatively, the method comprises the steps of milling a denture base so that it has a surface and at least one projection extending from the surface for spacing the surface adjacent to the projection from a tooth. Alternatively, the method comprises the steps of three dimensional printing a denture base having a surface for receiving a tooth and at least one projection extending from the surface for spacing the surface adjacent to the projection from the tooth.

EXAMPLES

Example 1

[0083] Experimental tests have been carried out to demonstrate that a bond between a denture base and a tooth of the invention is stronger compared to the bond between a denture base and a known tooth.

[0084] The experimental tests were based on the current ISO standard for denture base teeth (ISO 22112:2017). According to this standard, bonding of polymer teeth to denture base polymers is tested as follows.

[0085] Six maxillary anterior teeth from at least two different moulds are taken. The teeth are mounted on a metal former with dental mounting wax, so that about one half of the lingual surface of the incisal portion of the teeth and about one half of the teeth projects beyond the metal former. A denture flask is used to set the mounted teeth in dental gypsum. The metal mount is removed and then the wax is flushed from the teeth with boiling tap water.

[0086] The denture base polymer is processed to the teeth. In this regard, after proper plasticity has been reached, the clamped flask is submerged in water at 70° C. ± 3° C. in a water bath for 90 ± 1 minutes and finally immersed in boiling water in the water bath for 30 ± 1 minutes. When this heating procedure has been completed, the denture flask is cooled in the clamp in air until room temperature 23° C. ± 2° C. is reached.

[0087] The plastics mounted teeth are tested in a tensile testing apparatus designed to permit a direct pull on the incisal part of the lingual surface in a labial direction at a consistent height above the denture base polymer bar. Equipment that does not permit lateral deflection or change of position is used. Each tooth is loaded at a displacement rate in the range of 0.5 mm/min to 10 mm/rnin, until fracture occurs.

[0088] The bond between the teeth and the denture base passes the test if the mode of fracture is cohesive within the tooth or the denture base polymer, i.e. there are remnants of tooth remaining bonded to the denture base polymer or there are remnants of denture base polymer remaining bonded to the tooth.

[0089] Only pure adhesive interfacial fracture indicates a failure to pass the test.

[0090] However this standard test procedure replicates the method of processing teeth to denture base that was current at the time when the standard was written. Unlike in this older process the denture base will have already been produced either by milling or 3D printing and so the teeth will not be able to be mounted into wax and processed with the base as described in the standard. The following modification to the test method in the standard was therefore used in this test. [0091] 1 A cuboid having size 14 mm × 77 mm × 5 mm is formed in wax. [0092] 2 Prosthetic teeth without projections were coated with wax separating solution. The wax on one of the sides with dimensions 77 mm × 5 mm was then softened and the teeth were pressed into this side so that an outline of the surfaces of six upper anterior teeth having no projections was obtained (as shown in FIG. 10). The teeth were then carefully removed and processing of the denture base was carried out as described in the ISO standard except that Pegasus Pourable Acrylic, a self-curing PMMA acrylic was used and cured according to its instructions for use. [0093] 3 Once the tooth mount containing the denture base analogue had been cured, three teeth having no projections were placed onto one half of the denture base analogue and three teeth having projections were placed on the other half (as shown in FIG. 11). The teeth were held in position with wax that was applied outside the bonding surface. [0094] 4 A matrix of the vestibular surfaces of six upper anterior teeth was formed (as shown in FIG. 12) using light and putty silicone impression materials and the teeth and analogue denture base were removed. The teeth were separated from the base and steam cleaned to remove any wax residue. [0095] 5 The palatal surfaces of the teeth were cleaned with denture base monomer and replaced to their previous positions in the matrix. At the same time the bonding surfaces of the denture base analogue were also cleaned with denture base monomer. [0096] 6 A thin layer of Pegasus pourable Acrylic was then applied to all bonding surfaces and the denture base analogue was pressed onto the teeth till initial set had taken place (as shown in FIG. 13). Once initial set had taken place the pressure was removed and the ensemble was placed in a hydroflask and cured for 10 minutes at 40° C. and 2-3 bar pressure. [0097] 7 Once curing was completed, testing was carried out in accordance with the above ISO standard. [0098] 8 The comparative experimental tests showed that teeth according to the invention and having projections were extensively broken within the teeth themselves whereas teeth outside the scope of the invention and having no projections broke away from the denture base at the bonding surfaces themselves (as shown in FIG. 14). This clearly demonstrated a superior bond was achieved between a denture base and teeth having projections compared to the denture base and teeth having no projections.

Example 2

[0099] Comparative experimental tests were carried out to determine the technical effect of including projections extending from a surface of a tooth in order to provide precise positioning of the tooth on the denture base. In this regard, testing was carried out to compare an embodiment of the invention, wherein projections were included between a tooth and a denture base for providing a precise positioning on the denture base to an embodiment outside the scope of the invention having no projections extending from a tooth or denture base.

[0100] Upper and lower dentures were designed by means of design software together with teeth manufactured with an embodiment of the invention so that the teeth were ideally positioned both within each of the upper and lower dentures and relative to the teeth in the opposing denture so that both dentures were in perfect articulation and all teeth were correctly positioned on the bases.

[0101] A further set of upper and lower dentures were designed in exactly the same way but with teeth outside of the embodiment of the invention and having no projections.

[0102] In all cases space was left for the required thickness of cement to be applied. It was postulated that because of the projections extended from the surfaces that those teeth manufactured with the embodiment of the invention would be more precisely positioned on the base. The two sets of upper and lower denture bases were 3D printed but not post cured.

[0103] All tooth surfaces to come into contact with the denture base were sandblasted with 50 .Math.m aluminium oxide at 1 bar. Residues from the abrasive were removed using steam cleaning. In order to aid adhesion a thin layer of primer was then applied to the above surfaces using a microbrush and then cured. A thin layer of adhesive was then applied with a microbrush to the tooth spaces in the denture bases. The teeth were then inserted into the denture bases and pressed home so that excess cement was extruded from the margins and was then carefully removed with a microbrush. The cement was then cured together with the post cure of the 3D printed base.

[0104] Once curing was completed, a comparison was carried out.

[0105] The comparative experimental tests showed that teeth according to embodiments of the invention and having projections extending from the teeth for spacing the surface of the teeth adjacent to the projections from the surface of the denture base were in their correct orientations and precisely aligned. This enabled upper and lower teeth to be aligned correctly with respect to each other. In contrast, teeth outside the scope of the invention and having no projections were aligned less precisely and not in the exactly correct orientation. This resulted in upper and lower teeth being aligned incorrectly with respect to each other.

[0106] Although the present invention has been described with respect to a presently preferred embodiment, the present invention should not be limited to the embodiment, and it will be appreciated by those skilled in the art that various modifications may be made without departing from the spirit and scope of the present invention.