Method of making dental bridges, dental crowns, and dental corono-radicular retainers

Claim 1

A method of making a dental bridge, comprising the steps of: forming a negative cast of the mouth area adapted to receive said prosthesis with a casting material; thereafter forming a hard plaster positive model of said region by introducing plaster into only a limited region of said cast corresponding to the tooth-stump area and the alveolary crest area between the two stumps, producing an extended plaster positive model from said cast from which the tooth-stump model is removable, and removing the tooth-stump model from said extended model; casting a reversible hydrocolloid material about said model and withdrawing said model from said hydrocolloid material upon setting thereof to form a reversible hydrocolloid negative impression; casting in said negative impression an investment material to form a positive representation from said investment material; building up a thin layer of wax on said positive representation and shaping said layer to the configuration of the prosthesis to be fashioned; and forming a lost-wax casting mold about the positive representation with the wax layer thereon and casting a molten metal in said mold to produce the prosthesis, said reversible hydrocolloid negative impression being formed from said toothstump model and said positive impression of investment material constituting a duplicate of said tOoth-stump model, said toothstump model and the duplicate thereof of investment material forming cores corresponding to the teeth on either side of said alveolary crest area and of a dimension less than that of the teeth to be formed on said prosthesis, said thin layer of wax being built on said cores to the anatomical shape of teeth by applying a wax band of predetermined thickness around said cores and a wax disk to the ends of said cores.

Claim 2

A method of making a dental bridge, comprising the steps of: forming a negative cast of the mouth area adapted to receive said prosthesis with a casting material; thereafter forming a hard plaster positive model of said region by introducing plaster into only a limited region of said cast corresponding to the tooth-stump area and the alveolary crest area between the two stumps, producing an extended plaster positive model from said cast from which the tooth-stump model is removable, and removing the tooth-stump model from said extended model; casting a reversible hydrocolloid material about said model and withdrawing said model from said hydrocolloid material upon setting thereof to form a reversible hydrocolloid negative impression; casting in said negative impression an investment material to form a positive representation from said investment material; building up a thin layer of wax on said positive representation and shaping said layer to the configuration of the prosthesis to be fashioned; and forming a lost-wax casting mold about the positive representation with the wax layer thereon and casting a molten metal in said mold to produce the prosthesis, said reversible hydrocolloid negative impression being formed from said toothstump model and said positive impression of investment material constituting a duplicate of said tOoth-stump model, said toothstump model and the duplicate thereof of investment material forming cores corresponding to the teeth on either side of said alveolary crest area and of a dimension less than that of the teeth to be formed on said prosthesis, said thin layer of wax being built on said cores to the anatomical shape of teeth by applying a wax band of predetermined thickness around said cores and a wax disk to the ends of said cores.

Claim 4

The method of making a corono-radicular retainer comprising the steps of: forming a negative cast of the mouth area adapted to receive said prosthesis with a casting material; thereafter forming a plaster positive model of said region by introducing plaster into said cast; casting a reversible hydrocolloid material about said model and withdrawing said model from said hydrocolloid material upon setting thereof to form a reversible hydrocolloid negative impression; casting in said negative impression an investment material to form a positive representation from said investment material; building up a thin layer of wax on said positive representation and shaping said layer to the configuration of the prosthesis to be fashioned, said layer of wax being applied to said positive representation in the form of a wax band of a predetermined thickness of about 0.4 mm. and fixing a metallic taper dowel in said model, suspending said model in a container and casting said hydrocolloid material about said model in said container.

Claim 5

The method of making a corono-radicular retainer comprising the steps of: forming a negative cast of the mouth area adapted to receive said prosthesis with a casting material; thereafter forming a plaster positive model of said region by introducing plaster into said cast; casting a reversible hydrocolloid material about said model and withdrawing said model from said hydrocolloid material upon setting thereof to form a reversible hydrocolloid negative impression; casting in said negative impression an investment material to form a positive representation from said investment material; building up a thin layer of wax on said positive representation and shaping said layer to the configuration of the prosthesis to be fashioned, said layer of wax being applied to said positive representation in the form of a wax band of a predetermined thickness of about 0.4 mm. and fixing a metallic taper dowel in said model, suspending said model in a container and casting said hydrocolloid material about said model in said container.

Claim 7

A method of making a dental prosthesis, such as a dental bridge, dental crown or corono-radicular retainer, comprising the steps of: forming a negative cast of the mouth area adapted to receive said prosthesis with casting material; thereafter forming a plaster positive model of said region by introducing plaster into said cast; casting a reversible hydrocolloid material about said model and withdrawing said model from said hydrocolloid material upon setting thereof to form a reversible hydrocolloid negative impression; casting in said negative impression an investment material to form a positive representation from said investment material; building up a thin layer of wax on said positive representation and shaping said layer to the configuration of the prosthesis to be fashioned; and forming a lost-wax casting mold about the positive representation with the wax layer thereon and casting a molten metal in said mold to produce the prosthesis, said model being mounted on a wall of said container and the container is filled with said hydrocolloid material up to said wall and surrounds said model, said molten metal being a chromium-cobalt alloy, said investment material being cured at an elevated temperature prior to the build up of said layer of wax thereon.

Claim 8

A method of making a dental prosthesis, such as a dental bridge, dental crown or corono-radicular retainer, comprising the steps of: forming a negative cast of the mouth area adapted to receive said prosthesis with casting material; thereafter forming a plaster positive model of said region by introducing plaster into said cast; casting a reversible hydrocolloid material about said model and withdrawing said model from said hydrocolloid material upon setting thereof to form a reversible hydrocolloid negative impression; casting in said negative impression an investment material to form a positive representation from said investment material; building up a thin layer of wax on said positive representation and shaping said layer to the configuration of the prosthesis to be fashioned; and forming a lost-wax casting mold about the positive representation with the wax layer thereon and casting a molten metal in said mold to produce the prosthesis, said model being mounted on a wall of said container and the container is filled with said hydrocolloid material up to said wall and surrounds said model, said molten metal being a chromium-cobalt alloy, said investment material being cured at an elevated temperature prior to the build up of said layer of wax thereon.