Method and Apparatus for Shape Analysis, Storage and Retrieval of 3D Models with Application to Automactic Dental Restoration Design

A method for designing a tooth restoration comprising the steps of:

• a. encoding a margin line of a tooth preparation comprising
• i. obtaining a 3D model of a preparation of a tooth to be restored wherein the preparation comprises a margin;
• ii. virtually marking the margin of the preparation to form a margin line;
• iii. encoding the margin line by a curve encoding process comprising:
• sampling the margin line at sample points having a constant density;
• identifying local behavior over a set of adjacent sample points;
• and
• assigning a label to a sample point that identifies the behavior;
• and
• iv. linking the labels together to form a chain code;
• b. accessing a case repository comprising previously designed tooth restoration cases wherein each case comprises a digital 3D model of the previously designed tooth restorations and a chain code for an encoded margin line;
• c. searching the case repository by similarity measurements between the chain codes of the restoration cases and the chain code of the tooth preparation;
• d. retrieving a plurality of digital 3D models of the previously designed tooth restorations based on similarity measurements;
• e. selecting one of the digital 3D models for designing the tooth restoration for the patient;
• and
• f. modifying the digital 3D model to fit the tooth preparation.

A method for obtaining a design proposal comprising the steps of

• a) obtaining i) a digital 3D model of a dental preparation comprising a shape descriptor, and ii) digital data that represents the shape descriptor of the preparation;
• b) providing a case repository comprising a plurality of previously completed dental restoration cases wherein each case comprises
• i) a digital 3D model of a completed dental restoration comprising a shape descriptor, and
• ii) digital data that represents the shape descriptor of the completed dental restoration;
• c) searching the database by measuring similarity of the shape descriptor of the dental preparation and shape descriptors of the previously completed restoration cases;
• d) retrieving digital 3D models of a plurality of previously completed dental restoration cases as design proposals based on similarity between the shape descriptors of the previously completed restoration cases and the shape descriptor of the dental preparation.

A system for obtaining a design proposal comprising:

• one or more computing devices, at least one of which is configured to operate in a cloud computing system, and a plurality of program modules having instructions that are executable by the one or more computing devices, that provide instructions for performing process steps to obtain a design proposal comprising:
• a) obtaining i) a digital 3D model of a dental preparation comprising a shape descriptor, and ii) digital data comprising a representation of the shape descriptor of the dental preparation;
• b) accessing a case repository stored in the cloud computing system comprising a plurality of previously completed dental restoration cases wherein each case comprises
• i) a 3D digital model of the completed dental restoration comprising a shape descriptor, and
• ii) digital data that comprises a representation of the shape descriptor of the previously completed dental restoration;
• c) searching the digital data by similarity between the shape descriptor of the dental preparation and the shape descriptors of the previously completed restoration cases;
• d) retrieving a plurality of 3D digital models of the previously completed restoration cases that have shape descriptors most similar to the shape descriptors of the dental preparation as design proposals;
• and
• e) selecting one proposal as a restoration proposal.