PTAB

IPR2017-00081

Straumann Mfg Inc v. ZirCore LLC

Log In
Key Events
Petition
petition Intelligence

1. Case Identification

2. Patent Overview

  • Title: Dental Restoration Substructure
  • Brief Description: The ’920 patent discloses a dental restoration, such as a crown, comprising a porcelain veneer and an underlying substructure (coping). The purported invention is an annular support structure that protrudes from the substructure near the occlusal (biting) end to reinforce the veneer and reduce shear stress, thereby preventing fracture.

3. Grounds for Unpatentability

Ground 1: Anticipation over Shoher - Claims 1-3, 5, 6, and 9-21 are anticipated by Shoher under 35 U.S.C. §102.

  • Prior Art Relied Upon: Shoher (Patent 4,231,740).
  • Core Argument for this Ground:
    • Prior Art Mapping: Petitioner argued that Shoher, which was not considered during the original prosecution, discloses every limitation of the challenged claims. The core of the argument centered on Figure 1C of Shoher, which depicts a dental restoration with a substructure (20) and a "circumferential metal protuberance or belt" (24). Petitioner contended this belt is structurally and functionally identical to the ’920 patent’s claimed "support structure." The argument asserted that Shoher’s belt protrudes from the substructure sidewall, is located near but spaced from the occlusal end, encircles the periphery, and provides support to reduce veneer fracture, as evidenced by Shoher's own favorable impact strength test results.
    • Key Aspects: Petitioner presented side-by-side comparisons of Figure 1C from Shoher and Figure 2 from the ’920 patent to visually demonstrate that the size, shape, and location of the reinforcing structures are virtually identical.

Ground 2: Obviousness over Shoher in view of Bonnard - Claims 4, 7, 8, 15, and 16 are obvious over Shoher in view of Bonnard under 35 U.S.C. §103.

  • Prior Art Relied Upon: Shoher (Patent 4,231,740) and Bonnard (a 2001 journal article on esthetic rehabilitation).
  • Core Argument for this Ground:
    • Prior Art Mapping: Shoher was asserted to teach the fundamental dental restoration structure, including the reinforcing belt. Bonnard was cited for teaching several well-known modifications in the art. Specifically, Bonnard disclosed the use of all-ceramic (non-metal) substructures for superior aesthetics (for claim 4), the use of implant abutments as an alternative to prepared teeth for restorations (for claims 7 and 8), and the use of CAD-CAM software (the Procera® system) to design and manufacture such components (for claims 15 and 16).
    • Motivation to Combine: Petitioner argued a person of ordinary skill in the art (POSITA) would combine these teachings for predictable benefits. A POSITA would substitute a non-metal material for the metal substructure in Shoher to achieve known aesthetic improvements. Similarly, a POSITA would adapt the Shoher restoration for use with an implant abutment, as taught by Bonnard, for situations where a natural tooth is not available. Finally, a POSITA would have been motivated to use established CAD-CAM technology, as described in Bonnard, to design the Shoher substructure to achieve greater precision and efficiency than traditional methods.
    • Expectation of Success: The combination involved the simple substitution of one known element or process for another to obtain predictable results, giving a POSITA a reasonable expectation of success.

Ground 3: Obviousness over Shoher in view of Kurbad - Claims 17 and 18 are obvious over Shoher in view of Kurbad under §103.

  • Prior Art Relied Upon: Shoher (Patent 4,231,740) and Kurbad (a 2003 journal article on 3D software for dental labs).

  • Core Argument for this Ground:

    • Prior Art Mapping: This ground addressed claims 17 and 18, which recite specific software steps for creating the support structure, namely "identifying an outer contour shape for the substructure body" and "conforming... an annular protrusion shape to the outer contour shape." Petitioner asserted that Kurbad taught a CAD-CAM software feature called a "Drop" function, which digitally simulates the manual "waxing up" process. This function allowed a user to add material to a digital model, which automatically fused to the underlying structure by identifying the local contour and conforming the added material to it.
    • Motivation to Combine: A POSITA wanting to create the Shoher restoration using CAD-CAM would have been motivated to use a standard tool like the "Drop" function described in Kurbad. This would allow the POSITA to efficiently add the circumferential belt to the base coping design, thereby performing the exact "identifying" and "conforming" steps recited in the claims.
    • Expectation of Success: Applying a standard, known software function to a known design would have been a straightforward and predictable process.

  • Additional Grounds: Petitioner asserted additional obviousness challenges for the remaining claims based on similar design modification theories: claim 19 over Shoher in view of van der Zel (for using software libraries of pre-made shapes); claim 20 over Shoher in view of Perot (for using a subtractive method to design the substructure); and claim 21 over Shoher in view of Willer (for using milling to manufacture the restoration).

4. Key Claim Construction Positions

  • "said side wall including a generally uniform outer surface" (claim 1): Petitioner argued this term means that the substructure's side wall, apart from the protruding support structure, does not have significant variations and follows the conventional contour of a coping. This construction was used to map the main body of Shoher's substructure to the claim.
  • "location of greatest occlusal stress" (claim 1): Citing the Patent Owner's own infringement contentions, Petitioner asserted this location is toward the top of the substructure. This interpretation was used to argue that the reinforcing belt in Shoher is positioned in the claimed location.

5. Key Technical Contentions (Beyond Claim Construction)

  • Claims 15-21 are Product-by-Process Claims: Petitioner dedicated a substantial portion of its argument to the position that claims 15-21 do not add patentable structural limitations over claim 1. It argued these claims merely recite the process by which the restoration is designed or made (e.g., "determined through the use of a software application," "is milled"). Petitioner contended that because these process steps do not result in a structurally different product, the patentability of these claims rises and falls with claim 1. This argument underpinned the assertion that the anticipation of claim 1 by Shoher necessarily results in the anticipation of claims 15-21 as well.

6. Relief Requested

  • Petitioner requested institution of an inter partes review and cancellation of claims 1-21 of the ’920 patent as unpatentable.