Method for preparation of dental crowns and bridges

Claim 1

A method of preparing a natural tooth for the fitting of a dental crown or bridge with the use of a rotatable cutting burr supported in a handpiece and having a shading guide coextensive with, and rotatable about, said cutting burr and extending beyond the tip of said cutting burr for engagement sub-gingivally with said tooth, wherein the steps comprise fastening a block by its base, to the cusp of said tooth, said block having three pre-prepared external surfaces, a first one of said surfaces constituting said base, a second one of said surfaces being at an opposite part of said block to said base, and a third one of said surfaces being an external wall joining said first and said second surfaces; and operating said handpiece to effect progressive free-hand reduction of the tooth structure of said natural tooth until said handpiece abuts both of said second and third surfaces simultaneously with said extending part of said shading guide in contact with a sub-gingival part of said tooth thereby to provide controlled limits of said reduction.

Claim 2

A method of preparing a natural tooth for the fitting of a dental crown or bridge with the use of a rotatable cutting burr supported in a handpiece and having a shading guide coextensive with, and rotatable about, said cutting burr and extending beyond the tip of said cutting burr for engagement sub-gingivally with said tooth, wherein the steps comprise fastening a block by its base, to the cusp of said tooth, said block having three pre-prepared external surfaces, a first one of said surfaces constituting said base, a second one of said surfaces being at an opposite part of said block to said base, and a third one of said surfaces being an external wall joining said first and said second surfaces; and operating said handpiece to effect progressive free-hand reduction of the tooth structure of said natural tooth until said handpiece abuts both of said second and third surfaces simultaneously with said extending part of said shading guide in contact with a sub-gingival part of said tooth thereby to provide controlled limits of said reduction.

Claim 5

A method of producing a guide block for use in preparing a natural tooth for the fitting of a dental crown or bridge, wherein the steps comprise producing a cast from an impression of the natural tooth, creating on said cast with the use of a dental surveyor a model of the intended preparation of the natural tooth which includes a sub-gingival shoulder, temporarily attaching to the cusp of the model tooth so formed a mass of material having bottom and top surfaces and an outer face, so that said bottom surface contains an impression of the configuration of said cusp, preparing said outer face of said mass to form a side wall surface with the occlusal area of the model tooth serving as a guide, and forming said top surface on said mass corresponding contoured and parallel to a predetermined sub-gingival shoulder of the model tooth, thereby creating from said mass a block having three prepared external surfaces of which two serve as controlling limits on free-hand reduction of the natural tooth by a dental surgeon, and thence removing said block from said model tooth for supply as an aid to the dental surgeon.

Claim 6

A method of producing a guide block for use in preparing a natural tooth for the fitting of a dental crown or bridge, wherein the steps comprise producing a cast from an impression of the natural tooth, creating on said cast with the use of a dental surveyor a model of the intended preparation of the natural tooth which includes a sub-gingival shoulder, temporarily attaching to the cusp of the model tooth so formed a mass of material having bottom and top surfaces and an outer face, so that said bottom surface contains an impression of the configuration of said cusp, preparing said outer face of said mass to form a side wall surface with the occlusal area of the model tooth serving as a guide, and forming said top surface on said mass corresponding contoured and parallel to a predetermined sub-gingival shoulder of the model tooth, thereby creating from said mass a block having three prepared external surfaces of which two serve as controlling limits on free-hand reduction of the natural tooth by a dental surgeon, and thence removing said block from said model tooth for supply as an aid to the dental surgeon.