Dental shade matching for multiple anatomical regions

A shade matching method for a tooth, the method comprising:

• a) selecting a tooth and defining a grid on a buccal surface of the tooth;
• b) defining a mapping of the grid from the buccal surface to a 3D surface on a common 3D tooth shape, wherein the common 3D tooth shape is shared among a plurality of digitized tooth shade references each containing color information on a tooth shade reference;
• c) computing a shade label for each cell of the grid based at least in part on a correspondence between each cell of the grid and a region of at least one of the plurality of digitized tooth shade references;
• and
• d) storing shade labels for each of a plurality of cells of the grid.

An intraoral imaging apparatus, said apparatus comprising:

• an image capture apparatus that obtains a plurality of digitized tooth shade references, wherein each tooth shade reference corresponds to a common 3D tooth shape having a reference coordinate system, a label and color information on the common 3 D tooth shape;
• another image capture apparatus that obtains a 3D surface representation of a tooth and associated color information defined on the 3D surface representation;
• a processor that is programmed with processing logic instructions to:
• (a) select a region on the 3D surface representation of the tooth defined by coordinates of a tooth coordinate system;
• (b) determine a plurality of correspondences with regions of the common 3D tooth shape of all the plurality of digitized tooth shade references by mapping the coordinates for the region on the 3D surface representation to coordinates of the reference coordinate system, wherein the plurality of correspondences connects points from a same anatomical region between the selected region on the 3D surface representation of the tooth and the common 3D tooth shape;
• (c) compute a color difference for each tooth shade reference of the plurality of digitized tooth shade references, wherein each color difference is computed by a comparison of color information from a tooth shade reference with the associated color information from the selected region on the 3D surface representation of the tooth, wherein the comparison of color information uses the plurality of correspondences;
• and
• (d) record the label corresponding to the tooth shade reference with a smallest difference.

An intraoral imaging apparatus, said apparatus comprising:

• an image capture apparatus that obtains a plurality of digitized tooth shade references, wherein each tooth shade reference corresponds to a common 3D tooth shape having a reference coordinate system, a label and color information on the common 3D tooth shape, and the image capture apparatus that obtains a 3D surface representation of a tooth and associated color information defined on the 3D surface representation;
• a processor that is programmed with processing logic instructions to:
• (a) select a region on the 3D surface representation of the tooth defined by coordinates of a tooth coordinate system;
• (b) determine a plurality of correspondences with regions of the common 3D tooth shape of all the plurality of digitized tooth shade references by mapping the coordinates for the region on the 3D surface representation to coordinates of the reference coordinate system, wherein the plurality of correspondences connects points from a same anatomical region between the selected region on the 3D surface representation of the tooth and the common 3D tooth shape;
• (c) compute a color difference for each tooth shade reference of the plurality of digitized tooth shade references, wherein each color difference is computed by a comparison of color information from a tooth shade reference with the associated color information from the selected region on the 3D surface representation of the tooth, wherein the comparison of color information uses the plurality of correspondences;
• and
• (d) record the label corresponding to the tooth shade reference with a smallest difference.