Medit Corp v. 3Shape AS

1. Case Identification

• Case #: IPR2023-01315
• Patent #: 10,695,151
• Filed: August 18, 2023
• Petitioner(s): Medit Corporation
• Patent Owner(s): 3Shape A/S
• Challenged Claims: 1, 2, 4, 5, 9, 10, 12-17

2. Patent Overview

• Title: Detecting Tooth Shade
• Brief Description: The ’151 patent discloses methods and user interfaces for determining the shade of a patient's tooth. The technology involves obtaining a digital 3D representation of the tooth, which includes both shape and texture (color) data, and then determining a tooth shade value by comparing the texture data to known reference tooth shade values from a shade guide.

3. Grounds for Unpatentability

Ground 1: Anticipation of Claims 1, 12, 14, and 15 by Korten

• Prior Art Relied Upon: Korten (Patent 10,028,810).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Korten taught every limitation of independent claim 1. Korten disclosed a system for capturing a 3D virtual dentition model (shape data) and measuring color (texture data) at specific locations on the model. Korten further taught matching the measured color with a standard color from a scheme, such as the VITAPAN Classical tooth color scheme. Petitioner contended that Korten’s disclosure of "minimizing errors in color measurement" and determining the "degree of similarity" between a measured color and a reference color inherently taught the "deriving a certainty score" limitation, as this process requires calculating an accuracy value. Korten’s disclosure of using multiple scans to update a virtual model was argued to teach the sub-scan limitations of claims 14 and 15.

Ground 2: Obviousness of Claims 1, 2, 4, 5, 9, and 12-16 over Korten in view of Lehmann II

• Prior Art Relied Upon: Korten (Patent 10,028,810) and Lehmann II (Application # US 2011/0188086).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Korten provided the primary system for generating a 3D tooth model with correlated shape and color data. Lehmann II was introduced to teach limitations not explicitly found in Korten, primarily the "certainty score" and its visual display. Lehmann II disclosed a 2D image-based system that finds a "best fit or match" for a tooth shade by comparing RGB values against stored reference shades. Petitioner argued this "best fit" determination is equivalent to calculating a certainty score. Lehmann II also taught displaying the matched shade (e.g., "A2") on a monitor next to an image of the patient's tooth, which Petitioner argued taught generating and displaying a visual representation of the certainty score as required by claims 4 and 5.
  • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would combine Lehmann II's "best fit" matching algorithm with Korten's 3D scanning system to improve the accuracy of shade determination. Both references addressed the same problem of objective tooth shade matching and used similar underlying color systems, making the integration of Lehmann II's more specific matching technique into Korten's system a predictable improvement.
  • Expectation of Success: A POSITA would have a high expectation of success because combining a known 2D color analysis method with 3D color data was a straightforward application of known principles to achieve a more accurate result.

Ground 3: Obviousness of Claims 10, 16, and 17 over Korten and Lehmann II, in further view of Babayoff

• Prior Art Relied Upon: Korten (Patent 10,028,810), Lehmann II (Application # US 2011/0188086), and Babayoff (Patent 7,698,068).

• Core Argument for this Ground:

  • Prior Art Mapping: This ground built upon the Korten/Lehmann II combination and added Babayoff to address specific dependent claim limitations. For claim 10, Babayoff taught comparing texture data to known values for soft oral tissue by disclosing a method to differentiate hard tissues (teeth) from soft tissues (gums, cheeks) based on distinct color criteria. For claims 16 and 17, which require combining texture information from sub-scans by averaging or weighted averaging, Babayoff explicitly taught combining color data from multiple "sub-entities" or scans by "averaging the color value" and, optionally, "weight averaging the color value" at corresponding data points.
  • Motivation to Combine: A POSITA would be motivated to incorporate Babayoff's teachings into the Korten/Lehmann II system to solve known problems in intraoral scanning. Babayoff's tissue differentiation would improve scan accuracy by isolating tooth surfaces from gums, and its method for combining data from multiple scans would address the challenge of stitching sub-scans together more effectively.
  • Expectation of Success: Success was expected because all three references operate in the same technical field, use similar RGB color data, and address analogous problems. Integrating Babayoff's specific algorithms for tissue differentiation and data averaging was presented as a predictable enhancement to the base system.

• Additional Grounds: Petitioner asserted additional obviousness challenges, including claims over Korten in view of Lehmann I (Patent 6,206,691), and Korten in view of Pye (Patent 7,341,450), which relied on similar combination rationales to supply teachings on "best fit" correlation algorithms and tooth region averaging, respectively.

4. Key Claim Construction Positions

• Petitioner argued for applying the construction of the term "deriving a certainty score" adopted by the District Court in co-pending litigation.
• The proposed construction was: "determining an accuracy value based on the tooth shade value, the texture data, and/or texture information." This construction was critical to Petitioner's argument that Korten anticipated claim 1, as Korten's disclosure of measuring the "degree of similarity" or identifying a "mismatch" was argued to be a determination of an accuracy value.

6. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial would be improper under both §314(a) and §325(d).
• §314(a) (Fintiv): Petitioner stipulated that if the IPR is instituted, it will not pursue in the District Court the same grounds that were raised or could have reasonably been raised in the petition, per the framework in Sotera Wireless, Inc. v. Masimo Corp.
• §325(d): Petitioner argued that none of the prior art references relied upon were substantively considered or relied on by the examiner during the original prosecution of the ’151 patent. While Babayoff was used in a previously denied IPR petition against the same patent (IPR2023-00400), Petitioner contended its use and combination with other art in this petition was substantially different.

7. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claims 1, 2, 4, 5, 9, 10, and 12-17 of the ’151 patent as unpatentable under 35 U.S.C. §§ 102 and 103.