DCT

3:26-cv-02792

Weldental LLC v. Water Pik Inc

Key Events

Complaint

complaint Intelligence

I. Executive Summary and Procedural Information

Parties & Counsel:
- Plaintiff: Weldental LLC (Washington)
- Defendant: Water Pik, Inc. (Delaware); Church & Dwight Co., Inc. (Delaware)
- Plaintiff's Counsel: Law Offices Of Darren J. Quinn
Case Identification: 3:26-cv-02792, S.D. Cal., 05/01/2026
Venue Allegations: Plaintiff alleges venue is proper in the Southern District of California because Defendants have a regular and established place of business in the district, based on the presence of employees who conduct "Lunch & Learn Presentations," promote products, and receive company materials at designated physical addresses within the district.
Core Dispute: Plaintiff alleges that Defendants' "Boost Tip" for water flossers, which is designed to be used with treatment tablets, infringes a patent on a water flosser tip with an integrated chamber for holding and dissolving such a tablet.
Technical Context: The technology relates to oral hygiene, specifically combining the mechanical cleaning action of a water flosser with the delivery of a chemical treatment agent from a solid tablet.
Key Procedural History: The complaint alleges willful infringement, asserting that the patent-in-suit was cited during the prosecution of patent registrations owned by Defendant Water Pik, which may suggest pre-suit knowledge of the patent.

Case Timeline

Date	Event
2014-04-02	'178 Patent Priority Date
2017-08-08	'178 Patent Issued
2026-05-01	Complaint Filed

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

U.S. Patent No. 9,724,178 - "WATER FLOSSER TIP HAVING A CONTAINER FOR TREATMENT TABLETS"

Patent Identification: U.S. Patent No. 9,724,178, "WATER FLOSSER TIP HAVING A CONTAINER FOR TREATMENT TABLETS", issued August 8, 2017.

The Invention Explained

Problem Addressed: The patent's background section notes that while water flossers are used for cleaning between teeth, conventional devices "do not include a convenient way to provide treatment deep into the gum pockets to address periodontal diseases" '178 Patent, col. 1:19-23
The Patented Solution: The invention is a removable water flosser tip that includes a special chamber designed to hold a dissolvable treatment tablet '178 Patent, col. 2:27-30 As pressurized water from the flosser passes through this chamber, it dissolves the tablet and carries the treatment agent through the tip and into the user's mouth and gum pockets, thereby combining mechanical cleaning with a therapeutic treatment '178 Patent, col. 2:30-35 '178 Patent, abstract The internal structure, including diffusers, is intended to control the tablet's dissolution rate '178 Patent, col. 2:60-62
Technical Importance: This design provides an integrated method for delivering therapeutic agents during a water flossing routine without requiring separate steps or devices '178 Patent, col. 1:23-26

Key Claims at a Glance

The complaint asserts infringement of the '178 Patent generally, referencing an external claim chart not provided with the complaint Compl. ¶14 Claim 1 is the sole independent claim.
Essential elements of Independent Claim 1 include:
- An elongated tip with an orifice and an axial passage.
- A chamber connected to the elongated tip.
- A supply tube in sealed connection with the chamber, adapted for engagement with a pressurized water supply.
- The chamber is configured with "a pair of diffusers" positioned to hold a tablet in a "sandwiched position" between them.
- This configuration is such that pressurized water flows through, "partially dissolves and transports dissolved portions of said treatment tablet" through the tip.

III. The Accused Instrumentality

Product Identification

The primary accused product is the "Boost Tip" (Model WTT-1WW) Compl. ¶12.a The complaint also identifies a combination product, the "Ultra Plus & Boost Tip Combo Pack" (Model WP-150W/WTT-1), and various compatible Water Pik water flosser models Compl. ¶12.b Compl. ¶13

Functionality and Market Context

The complaint alleges the Boost Tip is an infringing product for use with Water Pik water flossers Compl. ¶3 An image provided in the complaint depicts the Boost Tip alongside a Water Pik flosser and a bottle of "WHITENING TABLETS," suggesting its function is to attach to the flosser and dispense a substance from the tablets during use Compl. ¶3 The complaint alleges Defendants market these products through their website and at "Lunch & Learn" presentations for dental professionals Compl. ¶9.b-c

IV. Analysis of Infringement Allegations

The complaint references a "Claim Chart attached as Exhibit A" to detail its infringement theory, but this exhibit was not included in the filing Compl. ¶14 The following analysis is based on the allegations and visual evidence provided in the complaint body.

'178 Patent Infringement Allegations

Claim Element (from Independent Claim 1)	Alleged Infringing Functionality	Complaint Citation	Patent Citation
A water flosser tip, comprising: an elongated tip, said elongated tip extending between a tip end having an orifice therein, to an opposite end; an axial passage running through said elongated tip, from said orifice to a distal end of a chamber connected to said elongated tip at said opposite end thereof;	The accused "Boost Tip" is a water flosser tip that attaches to a water flosser. An image shows the tip component that directs water flow. Compl. ¶3	¶3	col. 3:5-11
a supply tube having a passage therethrough, said passage in a sealed connection with a proximal end of said chamber at a first end of said supply tube, said passage extending to a distal end of said supply tube; said distal end of said supply tube adapted for engagement with a pressurized water supply;	The Boost Tip is designed to connect to Water Pik water flossers, which provide a pressurized water supply. Compl. ¶3 The images show the Boost Tip has a base for connecting to the flosser handle. Compl. ¶3	¶3	col. 3:12-18
and said chamber configured with a pair of diffusers positioned within the chamber, said diffusers adapted to hold said tablet in a sandwiched position in-between said pair of diffusers, such that the pressurized water supply ... partially dissolves and transports dissolved portions of said treatment tablet ...	The complaint alleges the Boost Tip is used with "WHITENING TABLETS." Compl. ¶3 An image shows the Boost Tip, the tablets, and the water flosser, implying the tip contains a chamber to hold the tablet for dissolution by water flow Compl. ¶3 The complaint provides no internal view or description of any "diffusers" or "sandwiched position."	¶3	col. 3:19-29

Identified Points of Contention:
- Structural Questions: The complaint lacks any specific allegation or evidence regarding the internal structure of the accused Boost Tip. A primary point of contention will be whether the Boost Tip contains structures that meet the "pair of diffusers" limitation and hold a tablet in a "sandwiched position" as claimed. The provided image shows the Boost Tip with a tablet, which is probative evidence of the accused product's intended use Compl. ¶3
- Scope Questions: The definition of "diffusers" will be critical. The patent specification suggests they "slow down the rate of dissolution" '178 Patent, col. 2:60-62 The court will have to determine if this functional aspect is a required part of the term's construction and, if so, whether any internal structures in the accused device perform that function.

V. Key Claim Terms for Construction

The Term: "a pair of diffusers"
Context and Importance: This term appears to be the central technical novelty recited in claim 1, distinguishing the invention from a simple chamber. Infringement will likely depend on whether the internal components of the accused Boost Tip can be characterized as a "pair of diffusers" that hold a tablet in a "sandwiched position." Practitioners may focus on this term because it adds a specific structural and potentially functional limitation beyond merely holding a tablet.
Intrinsic Evidence for Interpretation:
- Evidence for a Broader Interpretation: The patent also refers to the diffusers as "screens" '178 Patent, col. 2:58, which might support an argument that any pair of screen-like structures that retain the tablet would meet the limitation, regardless of their specific effect on dissolution.
- Evidence for a Narrower Interpretation: The specification explicitly describes a functional purpose: "The diffusers 18 may slow down the rate of dissolution of the tablet 20 when the device is in use" '178 Patent, col. 2:60-62 The figures also depict the diffusers as specific, multi-lobed components '178 Patent, FIG. 3 This language and depiction could support a narrower construction requiring structures that not only sandwich the tablet but are also configured to moderate its dissolution rate.

VI. Other Allegations

Indirect Infringement: The prayer for relief seeks an injunction against "inducement and contributory infringement" Compl. ¶18.a, though the body of the complaint focuses on direct infringement. The allegations that Defendants promote the products through their website and at "Lunch & Learn" events could form the basis for an inducement claim Compl. ¶9.b-c Compl. ¶9.h.ii
Willful Infringement: The complaint alleges Defendants' infringement has been "willful and deliberate" Compl. ¶16 The factual basis for this allegation is that the '178 Patent was "cited in Patent registrations owned by defendant WATER PIK," which Plaintiff presents as evidence of pre-suit knowledge Compl. ¶16

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

The resolution of this dispute will likely depend on the answers to two central questions:

A core question will be one of structural correspondence: does the accused Boost Tip contain the internal components claimed in the '178 patent, specifically "a pair of diffusers" that hold a treatment tablet in a "sandwiched position"? The complaint provides no direct evidence on this point, making it a critical issue for discovery.
A secondary question will be one of claim construction: what is the proper scope of the term "diffusers"? The case may turn on whether the term is construed broadly to mean any retaining screens, or more narrowly to require structures that perform the specific function of slowing the tablet's dissolution rate, as described in the patent's specification.

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