CAO Group Inc v. Zhu

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Cao Group, Inc. (Utah)
  • Defendant: Wencan Zhu (People's Republic of China); Nanchang White Technology Co. Ltd. (People's Republic of China); Radiant Harvest Inc. (Wyoming)
  • Plaintiff's Counsel: Law Office of Nicholas S. Lee
• Case Identification: 1:26-cv-06409, N.D. Ill., 06/23/2026
• Venue Allegations: Venue is alleged to be proper for the foreign defendants, Wencan Zhu and Nanchang White, as they are not residents of the United States and may be sued in any judicial district. For the domestic defendant, Radiant Harvest Inc., venue is based on a substantial part of the events, specifically sales into the district, occurring there.
• Core Dispute: Plaintiff alleges that Defendants' teeth whitening strips infringe a patent related to flexible dental whitening devices with specific visco-elastic gel compositions.
• Technical Context: The technology concerns consumer-grade, at-home teeth whitening products, specifically adhesive strips that conform to a user's teeth.
• Key Procedural History: The complaint asserts a single patent, U.S. Patent No. 11,826,444, which it states has expired. Consequently, the action seeks only monetary damages for past infringement. The patent's front page indicates a lengthy prosecution history as a continuation of several prior applications.

Case Timeline

Date	Event
2006-02-08	'444 Patent Priority Date
2023-11-28	'444 Patent Issue Date
2026-06-23	Complaint Filing Date

II. Technology and Patent(s)-in-Suit Analysis

• Patent Identification: U.S. Patent No. 11,826,444 ("Peroxide Gel Compositions"), issued November 28, 2023.

The Invention Explained

• Problem Addressed: The patent's background section describes drawbacks of prior art teeth whitening methods. These include the difficulty of keeping liquid treatments on teeth, the messiness of gels used in trays, and the tendency of early whitening strips to use gels that act as lubricants, causing the strips to move or fail to contact uneven teeth ʼ444 Patent, col. 1:33-40 ʼ444 Patent, col. 3:45-54 Additionally, more rigid compositions were prone to cracking or breaking when flexed ʼ444 Patent, col. 4:12-14
• The Patented Solution: The invention is a dental whitening device comprising a flexible backing strip coated with a specific type of dental composition. This composition is described as "gelatinous, non-coalescent, visco-elastic" and uses a thickening agent, such as polyvinylpyrrolidone (PVP), that is stable in a peroxide environment ʼ444 Patent, abstract ʼ444 Patent, col. 6:46-51 The key feature is that the combined strip and composition can flex to conform to the unique shape of a user's dental arch "without cracking or breaking," providing a customizable fit from a mass-produced product ʼ444 Patent, col. 8:22-30
• Technical Importance: The invention purports to provide a shelf-stable, conformable, and easy-to-use dental whitening strip that adheres well to teeth and effectively delivers the active agent, overcoming the messiness and poor fit of earlier systems ʼ444 Patent, col. 5:25-34

Key Claims at a Glance

• The complaint asserts at least independent Claim 1 Compl. ¶30
• The essential elements of Claim 1 are:
  • A dental whitening device comprising a strip of backing material that is flexible, planar, and has two flat sides.
  • A "gelatinous, non-coalescent, visco-elastic" dental composition conjoined to the backing strip.
  • The dental composition comprises a "tooth whitening agent," a solvent, and a thickening agent selected from a group consisting of polyethyloxazoline and polyvinylpyrrolidone (PVP).
  • When adhered to a user's dental arch, both the composition and the backing material "flex and conform to the user's dental arch without cracking or breaking."
• The complaint reserves the right to assert additional claims Compl. ¶32

III. The Accused Instrumentality

• Product Identification: The accused products are the "Purple Teeth Whitening Strips - 28 Teeth Whitener Strips (14 Uses)" sold under the brand name "Pdoo" on the Amazon.com marketplace Compl. ¶19
• Functionality and Market Context: The products are described as teeth whitening strips sold to consumers in the United States Compl. ¶19 Compl. ¶20 The complaint alleges that the products are manufactured in China by Defendant Nanchang White and sold through an Amazon storefront operated by Defendant Zhu, using Defendant Radiant Harvest (a Wyoming corporation) as the seller of record Compl. ¶7 Compl. ¶8 Compl. ¶21 The complaint includes a screenshot from the Amazon product listing, which displays the product packaging and its ingredient list Compl. ¶19 Compl. Exhibit 3 The ingredient list is the primary basis for the complaint's allegations regarding the product's chemical composition Compl. ¶22

IV. Analysis of Infringement Allegations

'444 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
a strip of backing material, wherein the strip of backing material is flexible and planar such that the strip of backing material has two flat sides	The accused product is a dental whitening device comprising a strip of backing material that is flexible and planar with two flat sides.	¶33	col. 8:11-14
a gelatinous, non-coalescent, visco-elastic dental composition conjoined to at least a portion of one of the flat sides of the strip of backing material	Based on inspection of a sample, the dental composition is alleged to be gelatinous, non-coalescent, and visco-elastic.	¶37	col. 5:54-6:3
the dental composition being comprised of a tooth whitening agent, a solvent, and a thickening agent selected from the set of thickening agents consisting of polyethyloxazoline and polyvinylpyrrolidone (PVP)	The product's packaging discloses "Phthalimidoperoxycaproic Acid" (PAP) as the whitening agent, "Aqua" as the solvent, and "PVP" (polyvinylpyrrolidone) as the thickening agent, which is one of the two agents recited in the claim.	¶34; ¶35; ¶36	col. 10:10-11
wherein when adhered to a user's dental arch both the dental composition and the backing material flex and conform to the user's dental arch without cracking or breaking	Based on inspection and application instructions, the accused product and its composition are alleged to flex and conform to a user's dental arch without cracking or breaking.	¶38	col. 8:22-25

• Identified Points of Contention:
  • Scope Questions: Claim 1 requires a "tooth whitening agent." The patent's specification is heavily focused on peroxide-based compositions ʼ444 Patent, title ʼ444 Patent, abstract ʼ444 Patent, col. 1:33-34 The complaint alleges the accused product uses Phthalimidoperoxycaproic Acid (PAP), a non-peroxide agent Compl. ¶34 This raises the question of whether the term "tooth whitening agent," in the context of this patent, can be construed to cover non-peroxide whiteners like PAP. The specification's statement that "other active ingredients may be added...with or without peroxide" may support a broader construction ʼ444 Patent, col. 10:4-6
  • Technical Questions: The complaint alleges, "based on inspection of an actual sample," that the accused product's composition is "gelatinous, non-coalescent, and visco-elastic" Compl. ¶37 A central evidentiary question will be whether the physical properties of the accused gel meet these claimed characteristics, especially in light of the specific definition of "gelatinous" provided in the patent's specification ʼ444 Patent, col. 5:54-6:3

V. Key Claim Terms for Construction

• The Term: "gelatinous, non-coalescent, visco-elastic"

• Context and Importance: These terms describe the core physical properties of the claimed dental composition, distinguishing it from prior art liquids or brittle solids. The infringement finding will depend heavily on whether the accused product's gel is proven to possess this specific combination of characteristics.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: A party could argue these terms should be given their plain and ordinary meaning to a person of skill in the art of material science or polymer chemistry at the time of the invention.
  • Evidence for a Narrower Interpretation: The specification provides an explicit definition for "gelatinous," citing a dictionary and providing functional descriptions, such as how discrete units "will not merge into one body" ʼ444 Patent, col. 5:54-6:3 This specific definition may be used to argue for a narrower, more limiting construction of the term.

• The Term: "tooth whitening agent"

• Context and Importance: The construction of this term is critical because the accused product allegedly uses a non-peroxide agent (PAP), while the patent's title, abstract, and background are overwhelmingly focused on peroxide.

• Intrinsic Evidence for Interpretation:

  • Evidence for a Broader Interpretation: A party could argue the term's plain meaning is not limited to a specific chemical class. This position may be supported by the specification's disclosure that "other active ingredients may be added to the composition... with or without peroxide" ʼ444 Patent, col. 10:4-6
  • Evidence for a Narrower Interpretation: A party could argue that the patent, titled "Peroxide Gel Compositions", is fundamentally directed to solving problems unique to peroxide-based gels. The repeated and central focus on peroxide throughout the specification (e.g., ʼ444 Patent, col. 1:41-47; ʼ444 Patent, col. 6:12-16) could support an argument that "tooth whitening agent" should be construed as being limited to peroxide or its adducts.

VI. Other Allegations

• Indirect Infringement: The complaint makes a passing allegation of direct and/or indirect infringement Compl. ¶30 but does not plead specific facts to support a claim for either induced or contributory infringement. The substantive allegations focus on direct infringement through making, selling, and importing the accused products Compl. ¶31
• Willful Infringement: The complaint alleges that Defendants' infringement was willful Compl. ¶24 Compl. ¶41 The allegations are based on knowledge of the patent or an "objectively high likelihood" of infringement Compl. ¶25 The complaint further alleges that Defendants took "deliberate steps... to conceal the foreign origin and ownership of their operation" by incorporating a U.S. entity (Radiant Harvest Inc.) "to create the false appearance that the 'Pdoo' storefront was operated by a domestic seller" and to "evade and frustrate enforcement of... intellectual property rights" Compl. ¶26

VII. Analyst's Conclusion: Key Questions for the Case

1. A core issue will be one of definitional scope: Will the term "tooth whitening agent", from a patent heavily focused on peroxide chemistry, be construed broadly enough to read on the non-peroxide Phthalimidoperoxycaproic Acid (PAP) used in the accused products?

2. A key evidentiary question will be one of technical characterization: Will factual discovery and expert testing demonstrate that the accused Pdoo product's gel possesses the specific "gelatinous, non-coalescent, visco-elastic" physical properties required by Claim 1, particularly as those terms may be narrowly defined by the patent's own specification?

3. A central question for damages will relate to willfulness: Can the plaintiff prove its allegations that the defendants deliberately structured their business using a U.S. shell corporation for the purpose of evading intellectual property enforcement, potentially supporting a finding of willful infringement and enhanced damages?