# US 2016/0256246 A1 · Negative and positive merge modelling > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2016/0256246 A1 - Document ID: US20160256246A1 - Status: Published application - Kind: A1 - Application number: 14/635,123 - Filed: 2015-03-02 - Published: 2016-09-08 - Earliest claimed: 2015-03-02 - Assignees: Sun Dental Holding, LLC. - Applicants: Sun Dental Holding, LLC. - Inventors: Charles Stapleton; Drew Fabiano - Web page: https://patentgrep.com/patent/US20160256246A1 ## CPC - A61C 13/34: Making or working of models, e.g. preliminary castings, trial dentures; Dowel pins [4] - A61C 13/0004: {Computer-assisted sizing or machining of dental prostheses} - A61C 13/0006: {Production methods} - G06T 17/00: Three-dimensional [3D] modelling for computer graphics - A61C 5/77: Methods or devices for making crowns - A61C 13/097: characterised by occlusal profiles {, i.e. chewing contact surfaces} - G06T 2210/41: Medical - G16H 20/40: relating to mechanical, radiation or invasive therapies, e.g. surgery, laser therapy, dialysis or acupuncture - A61C: DENTISTRY; APPARATUS OR METHODS FOR ORAL OR DENTAL HYGIENE (non-driven toothbrushes A46B; {tongue scrapers A61B17/24;} preparations for dentistry A61K6/00; preparations for cleaning the teeth or mouth A61K8/00, A61Q11/00) - G06T: IMAGE DATA PROCESSING OR GENERATION, IN GENERAL - G16H: HEALTHCARE INFORMATICS, i.e. INFORMATION AND COMMUNICATION TECHNOLOGY [ICT] SPECIALLY ADAPTED FOR THE HANDLING OR PROCESSING OF MEDICAL OR HEALTHCARE DATA ## Abstract The technology relates to modelling a prepared tooth for fitting a prosthetic thereon. A die, representative of a prepared tooth, may be modelled as a positive virtual three-dimensional die model. An impression of a set of teeth surrounding and including the prepared tooth may be modelled as a negative virtual three-dimensional impression model. The negative virtual three-dimensional impression may be inverted to create a positive virtual three-dimensional impression model. The positive virtual three-dimensional impression model and the positive virtual three-dimensional die model may then be merged to create a virtual three-dimensional dentition model. ## Claims ### Claim 1 A method for modelling a patient's prepared tooth for assisting in preparing or fitting a prosthetic therefor, comprising: scanning a negative impression of the patient's dentition, including at least the teeth surrounding and including the prepared tooth, to create a computer-generated negative virtual three-dimensional impression model which represents the negative impression of the patient's dentition; scanning a positive die created from a negative impression of the patient's dentition, which yields a computer-generated positive virtual three-dimensional die model representative of a limited part of the patient's dentition containing at least the prepared tooth; inverting the negative virtual three-dimensional impression model to create a positive virtual three-dimensional impression model; and merging the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model to create a virtual three-dimensional dentition model. ### Claim 2 (depends on 1) The method of claim 1, wherein the prepared tooth includes one or more teeth. ### Claim 3 (depends on 1) The method of claim 1, wherein the positive die is created by: pouring a material which can be cast into the negative impression; trimming the die down to a boundary outlining the prepared tooth and/or teeth adjacent the prepared tooth. ### Claim 4 (depends on 1) The method of claim 1, wherein the negative impression includes at least part of the patient's dentition opposing the prepared tooth. ### Claim 5 (depends on 1) The method of claim 1 further including, aligning the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model. ### Claim 6 (depends on 5) The method of claim 5 wherein aligning the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model includes performing n-point registration. ### Claim 7 (depends on 5) The method of claim 5, wherein aligning the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model includes removing extraneous portions of the positive three-dimensional die model. ### Claim 8 (depends on 1) The method of claim 1, wherein the merging includes removing a portion of the positive virtual 3D impression model which represents the prepared tooth. ### Claim 9 (depends on 8) The method of claim 8, wherein the merging further includes expanding the portion of the positive virtual 3D impression model representing the prepared tooth prior to removing the portion. ### Claim 10 (depends on 8) The method of claim 8, wherein the merging further includes bridging the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model. ### Claim 11 A system for producing a virtual three-dimensional dentition model for modelling a patient's prepared tooth for assisting in preparing and fitting a prosthetic therefor, comprising: one or more computing devices; one or more scanning devices communicatively coupled to the computing device; and a memory storing instructions, the instructions executable by the one or more computing devices and/or scanning devices; wherein the instructions comprise: scanning, by the one or more scanning devices, a negative impression of the patient's dentition, including at least the teeth surrounding and including the prepared tooth, to create optionally with said computing device a negative virtual three-dimensional impression model; scanning, by the one or more scanning devices, a positive die created from a negative impression of the patient's dentition, which is a positive representation of a limited part of the patient's dentition containing at least the prepared tooth, to create optionally with said computing device a positive virtual three-dimensional die model; inverting, by the one or more computing devices, the negative virtual three-dimensional impression model to create a positive virtual three-dimensional impression model; and merging, by the one or more computing devices, the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model to create a virtual three-dimensional dentition model. ### Claim 12 (depends on 11) The method of claim 11, wherein the positive die is created by: pouring a material which can be cast into the negative impression; trimming the die down to a boundary outlining the prepared tooth and/or teeth adjacent the prepared tooth. ### Claim 13 (depends on 11) The system of claim 11, wherein the negative impression includes at least part of the patient's dentition opposing the prepared tooth. ### Claim 14 (depends on 11) The system of claim 11 wherein the one or more computing devices aligns the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model. ### Claim 15 (depends on 14) The system of claim 14 wherein the one or more computing devices align the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model by performing n-point registration. ### Claim 16 (depends on 14) The system of claim 14, wherein the one or more computing devices aligning the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model includes removing extraneous portions of the positive three-dimensional die model. ### Claim 17 (depends on 11) The system of claim 11, wherein the one or more computing devices merging includes removing a portion of the positive virtual 3D impression model which represents the prepared tooth. ### Claim 18 (depends on 17) The system of claim 17, wherein the one or more computing devices merging further includes expanding the portion of the positive virtual 3D impression model representing the prepared tooth prior to removing the portion. ### Claim 19 A non-transitory computer-readable medium storing instructions, which when executed cause one or more processors to: scan a negative impression of the patient's dentition, including at least the teeth surrounding and including the prepared tooth, to create a computer-generated negative virtual three-dimensional impression model; scan a positive die created from a negative impression of the patient's dentition, which yields a computer-generated positive virtual three-dimensional die model representative of a limited part of the patient's dentition containing at least the prepared tooth; invert the negative virtual three-dimensional impression model to create a positive virtual three-dimensional impression model; and merge the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model to create a virtual three-dimensional dentition model. ### Claim 20 (depends on 19) The non-transitory computer-readable medium of claim 19, storing further instructions that when executed cause the one or more processors to align the positive virtual three-dimensional impression model and the positive virtual three-dimensional die model by performing n-point registration.