United States Patent 5,538,715: Claim Scope, Expiration, and Triclosan Dentifrice Patent Landscape

U.S. Patent No. 5,538,715 covers dentifrice compositions that combine a substantially water-insoluble, non-cationic antibacterial agent, especially triclosan, with a maleic acid or maleic anhydride copolymer that improves delivery and retention on teeth and gingival tissues. The narrowest commercially relevant embodiment is a toothpaste containing triclosan, a methyl vinyl ether-maleic acid or maleic anhydride copolymer, and propylene glycol.

The patent issued July 23, 1996. Its U.S. patent term expired in 2013 under the pre-1995 filing-date patent-term regime. The patent therefore has no current blocking effect against generic or branded U.S. products. Its historical importance is tied to the formulation architecture later associated with triclosan-containing toothpaste, including Colgate Total.

What does U.S. Patent 5,538,715 protect?

The patent protects an oral dentifrice composition that improves the delivery of an antibacterial agent to tooth and gum surfaces and increases retention of that agent near the gingival margin.

The central formulation elements are:

Element	Claim 1	Claim 2	Claim 16
Oral aqueous humectant vehicle	Required	Required	Required
Siliceous polishing agent	5-30%	5-30%	About 5-30%
Antibacterial agent	Required	Required	Triclosan
Antibacterial concentration	0.01-5%	0.01-5%	About 0.01-5%
Delivery or retention enhancer	Broad functional class	Maleic acid/anhydride copolymer	Maleic acid/anhydride-methyl vinyl ether copolymer
Solubilizer	0.5-50%	0.5-50%	Propylene glycol
Polyphosphate anticalculus exclusion	Required	Required	Not expressly recited
Polyethylene glycol exclusion	Required	Required	Not expressly recited

The claims are composition claims, not method-of-treatment claims. They require the listed ingredients to be present in a dentifrice, but they do not claim a separate method of applying the product, a treatment regimen, a manufacturing process, or a particular packaging system.

How broad are independent claims 1 and 2?

Claim 1: broad functional delivery-enhancer claim

Claim 1 is the broadest claim in the patent. It covers a dentifrice containing:

An orally acceptable aqueous humectant vehicle;
5-30% siliceous polishing agent;
An antibacterial agent;
0.01-5% of a water-soluble or water-swellable antibacterial-enhancing agent;
An enhancing agent with at least one carboxylic delivery-enhancing group and at least one organic retention-enhancing group;
0.5-50% of a solubilizing material; and
No effective polyphosphate anticalculus amount and no polyethylene glycol that effectively inhibits antibacterial activity.

Claim 1 is not limited to the maleic acid or methyl vinyl ether copolymer later recited in claims 2-5. The enhancing agent could theoretically be any material satisfying the molecular-weight, water-solubility or swellability, functional-group, delivery, and retention limitations.

The principal scope issue is functional claiming. The claim requires the enhancer to improve delivery and retention, but it does not define those effects by a numerical test. In litigation, infringement would likely turn on formulation composition, technical testing, product specifications, and expert interpretation of “enhances delivery” and “enhances attachment, adherence or bonding.”

Claim 2: narrower copolymer claim

Claim 2 replaces the broad enhancer category with a specific anionic copolymer:

Maleic acid or maleic anhydride; and
Another ethylenically unsaturated polymerizable monomer.

The copolymer must be present at 0.05-5% and must enhance delivery and attachment of the antibacterial agent.

This claim is narrower in chemical structure but remains commercially important because it covers the maleic acid or maleic anhydride copolymer platform used with triclosan. The claim does not require methyl vinyl ether. That limitation enters through dependent claim 3.

What do claims 3 through 5 add?

Claims 3-5 progressively narrow the copolymer:

Claim	Added limitation
3	The comonomer is methyl vinyl ether, in a 4:1 to 1:4 molar ratio with maleic acid or anhydride
4	Copolymer molecular weight is about 30,000-1,000,000 and concentration is about 0.1-2%
5	Average molecular weight is about 70,000

The commercially significant sequence is therefore:

Maleic acid or maleic anhydride copolymer;
Methyl vinyl ether as the second monomer;
Molecular weight between about 30,000 and 1,000,000;
Concentration between about 0.1% and 2%; and
Preferred average molecular weight of about 70,000.

This claim structure gives the patent multiple fallback positions. A challenger might avoid claim 5 by using a different molecular weight while remaining within claims 2-4. Conversely, a formulation outside the methyl vinyl ether limitation could avoid claims 3-5 but still face claim 2 if the copolymer satisfies its broader language.

Which antibacterial agents fall within the patent?

Claims 6-10 identify several antibacterial categories:

Halogenated diphenyl ethers;
Halogenated salicylanilides;
Benzoic esters;
Halogenated carbanilides;
Phenolic compounds;
Phenol;
Thymol;
Eugenol; and
2,2'-methylene bis(4-chloro-6-bromophenol).

Claim 8 specifically identifies 2,4,4'-trichloro-2'-hydroxydiphenyl ether, commonly known as triclosan.

The patent therefore does not depend exclusively on triclosan. Its claims also reach other antibacterial agents if the formulation satisfies the vehicle, polishing-agent, polymer, solubilizer, and concentration requirements.

What does claim 16 cover?

Claim 16 is an independent claim directed to the most recognizable product configuration:

Aqueous humectant dentifrice vehicle;
5-30% siliceous polishing agent;
0.01-5% triclosan;
0.05-5% maleic acid or maleic anhydride-methyl vinyl ether copolymer; and
Sufficient propylene glycol to dissolve triclosan in saliva.

Claim 16 does not expressly repeat the polyphosphate and polyethylene glycol exclusions from claims 1 and 2. Because it is an independent “comprising” claim, it is open-ended. A product can infringe while containing additional ingredients, unless those ingredients negate another express limitation or prevent the composition from meeting the claimed functional requirements.

Claim 16 is narrower than claim 1 because it specifies triclosan, the copolymer class, and propylene glycol. It is broader than claim 5 in some respects because it does not require the 70,000 molecular-weight limitation.

How do the dependent claims affect infringement analysis?

Claims 6-15 add optional limitations to claims 1 or 2:

Claims 6-10 narrow the antibacterial agent;
Claims 11-12 specify antibacterial concentration;
Claims 13-14 narrow the solubilizer, with claim 14 requiring propylene glycol;
Claim 15 adds an anticaries-effective fluoride source.

A product containing triclosan at 0.25-0.5%, propylene glycol, fluoride, and the claimed copolymer could fall within several overlapping claim paths, including claims 2, 3, 4, 6, 7, 8, 11, 12, 13, 14, and 15.

The “comprising” language is material. The claims do not exclude other conventional toothpaste components such as fluoride salts, flavor oils, sweeteners, surfactants, binders, preservatives, or desensitizing agents, provided the complete formulation still meets the claimed limitations.

What formulations are protected by the patent?

The patent is aimed at formulations in which triclosan is difficult to deliver or retain because it is substantially water insoluble. The copolymer and solvent system addresses two formulation functions:

Triclosan solubilization

Propylene glycol and the listed alternative solubilizers improve triclosan incorporation and dissolution in saliva. The claim does not require complete dissolution in the finished toothpaste. It requires an amount sufficient to dissolve the antibacterial agent in saliva and permit delivery to soft tissues near the gum line.

Oral-surface retention

The anionic maleic acid or maleic anhydride copolymer is claimed as a delivery and retention aid. The intended technical effect is increased deposition or persistence of the antibacterial agent on tooth and gum surfaces.

Siliceous polishing system

The 5-30% siliceous polishing-agent limitation distinguishes the claimed products from non-silica dentifrices. A formulation based primarily on calcium carbonate or another non-siliceous abrasive would have a substantial noninfringement position against claims requiring a siliceous polishing agent.

Polyethylene glycol exclusion

Claims 1 and 2 exclude polyethylene glycol when it effectively inhibits the oral antibacterial activity of the non-cationic antibacterial agent. This is a functional exclusion, not a blanket ban on every trace amount of polyethylene glycol.

What are the strongest design-around options?

Potential design-around routes include:

Design-around route	Claims most directly affected
Replace triclosan with a different antibacterial agent	Claims 6-12 and 16
Use a cationic antibacterial agent	Claim 2 and related non-cationic limitations
Replace maleic acid/maleic anhydride copolymer	Claims 2-5 and 16
Use a non-siliceous polishing system	Claims 1, 2, and 16
Use a delivery system other than the claimed polymer	Claims 1-5
Use a different solubilization technology	Claims 1, 2, 13, 14, and 16
Omit or alter the claimed concentration ranges	All concentration-limited claims
Use a formulation with no claimed antibacterial agent	All substantive claims

Claim 1 creates the principal risk for a non-maleic-acid design because it reaches a broader class of delivery and retention enhancers. A design-around that avoids the specific copolymer may still require analysis under claim 1.

A formulation using a different polymer must also be assessed against the functional terms in claim 1. Structural differences alone do not resolve infringement if the alternative polymer satisfies the claimed functional-group and delivery/retention requirements.

When did U.S. Patent 5,538,715 lose exclusivity?

U.S. Patent 5,538,715 issued on July 23, 1996. Because the application was filed under the pre-June 8, 1995 patent-term rules, the operative term was generally 17 years from issuance, subject to applicable adjustments. The patent expired in 2013.

The expiration eliminated U.S. patent exclusivity for the claimed compositions. It also eliminated the need for a Paragraph IV challenge against this patent for a later-filed abbreviated new drug application.

Was the patent subject to Paragraph IV challenges?

Paragraph IV certification applies when an ANDA applicant seeks approval for a product referencing a listed drug and certifies that an Orange Book patent is invalid, unenforceable, or not infringed.

Patent 5,538,715 was a formulation patent, not a currently enforceable Orange Book barrier. After its expiration, it could not support a prospective 30-month stay. Historical litigation or certification activity involving triclosan toothpaste products would need to be tied to the specific listed drug, Orange Book listing, and patent record. The supplied claim set does not establish a particular Paragraph IV notice, ANDA number, or litigation docket.

What is the Orange Book status of the patent?

Patent 5,538,715 is not a current exclusivity obstacle in the Orange Book because it expired in 2013. Orange Book status must be separated from FDA product approval:

A patent can expire while the drug product remains FDA-approved.
A patent can be listed for an NDA product without covering every product in the therapeutic category.
Orange Book listing does not determine infringement by itself.
Expired patents cannot create a new statutory stay for an ANDA applicant.

Colgate Total historically relied on triclosan-containing oral-care products in the United States. FDA later approved a reformulated Colgate Total product using stannous fluoride rather than triclosan. FDA’s action concerning triclosan-containing consumer products and oral-care products must be analyzed separately from patent status. [FDA, 2016; FDA, 2019]

What is the FDA regulatory status of triclosan toothpaste?

Triclosan toothpaste occupies a different regulatory position from triclosan-containing consumer antiseptic washes.

The FDA has taken action against certain consumer antiseptic products containing triclosan after concluding that manufacturers had not demonstrated the required long-term safety and effectiveness for those uses. That action did not automatically invalidate every historical toothpaste approval or eliminate every use of triclosan in oral-care formulations.

For FDA-approved toothpaste products, the relevant questions are:

Whether the product has an approved NDA;
Whether triclosan is an approved active ingredient for that product;
Whether the product has an applicable anticaries or gingivitis indication;
Whether the product has been reformulated; and
Whether the NDA remains marketed or has been withdrawn.

Patent expiration and FDA approval are separate regulatory events. [FDA, 2016; FDA, 2019]

How strong was the patent estate?

The patent had moderate historical strength as a formulation patent and limited present-day strength because it is expired.

Strengths

Claim 1 covered a broad functional enhancer category.
Claim 2 targeted a commercially relevant maleic acid or maleic anhydride copolymer.
Claim 16 directly covered the triclosan-copolymer-propylene glycol combination.
The “comprising” language allowed additional conventional toothpaste ingredients.
Multiple dependent claims created fallback positions based on antibacterial identity, concentration, solvent, and fluoride.

Weaknesses

The patent expired in 2013.
Many limitations are functional, including enhanced delivery, retention, and salivary solubilization.
Claim 1 requires a combination of structural and performance characteristics that could create proof issues.
The claims are composition claims and do not cover manufacturing methods or broad methods of treating gingivitis.
A competitor could use a different antibacterial agent, polymer, solvent, or abrasive platform.

The patent was commercially meaningful when triclosan toothpaste remained a major product category. It is now primarily relevant to historical freedom-to-operate analysis, validity studies, prosecution strategy, and prior-art mapping.

What licensing deals or ownership issues are relevant?

The patent claims provided do not identify a license, assignment, covenant not to sue, settlement, or co-development agreement. Patent ownership and commercial supply relationships should be distinguished:

The patent holder controlled the patent rights.
A polymer supplier could own separate manufacturing or composition patents.
An antibacterial supplier could own separate triclosan production or purification rights.
A toothpaste manufacturer could commercialize a product under license, supply agreement, or internal ownership.
None of those commercial relationships would extend the expired term of Patent 5,538,715.

No current licensing restriction can arise from this expired U.S. patent alone.

What litigation and settlement issues affect the patent?

The supplied information does not establish an active infringement action, settlement agreement, consent judgment, or license involving Patent 5,538,715. Any historical dispute would have to be evaluated by:

Court docket;
Asserted claims;
Claim-construction rulings;
Validity defenses;
Infringement contentions;
Settlement terms; and
Whether the dispute involved the patent itself or a related patent family member.

A settlement involving another triclosan, dentifrice, or copolymer patent would not automatically affect the legal status of Patent 5,538,715.

How does this patent compare with competing patent categories?

Patent category	Coverage	Relevance to 5,538,715
Antibacterial active-ingredient patents	Triclosan or alternative antibacterial compounds	Separate chemical protection
Dentifrice formulation patents	Vehicle, abrasive, surfactant, flavor, polymer, or solvent combinations	Closest overlap
Delivery and retention patents	Deposition of antibacterial agents on oral surfaces	Technical overlap with claims 1-5
Fluoride anticaries patents	Fluoride compositions and anticaries use	Complementary, not necessarily overlapping
Manufacturing patents	Polymer production, triclosan synthesis, mixing, granulation	Not claimed by 5,538,715
Method-of-use patents	Treatment of plaque, gingivitis, or periodontal disease	Not claimed by 5,538,715
Packaging patents	Tube, pump, dual chamber, or stability systems	Outside the patent’s scope

The principal competitive landscape involved formulation patents and product-specific regulatory approvals rather than biosimilar competition. Biosimilar risk is not applicable because triclosan is a small-molecule antibacterial agent, not a biologic.

What is the geographic coverage?

Patent 5,538,715 provides U.S. protection only. Parallel rights would require separate patents in jurisdictions such as Europe, Canada, Japan, or Australia. Expiration in the United States does not establish expiration dates in other countries.

Foreign equivalents may have had different:

Filing dates;
Claim scope;
Opposition histories;
Patent-term adjustments;
Supplementary protection rights; and
Expiration dates.

A current international freedom-to-operate review therefore cannot rely on the U.S. patent alone.

What was the commercial exposure?

The commercial exposure was concentrated in triclosan-containing toothpaste products, particularly products using a silica abrasive, propylene glycol, and a maleic acid or maleic anhydride-methyl vinyl ether copolymer.

The patent did not cover an entire toothpaste business. It covered a specific formulation architecture. Revenue exposure would depend on:

The percentage of product sales using triclosan;
The use and concentration of the claimed copolymer;
The presence of propylene glycol;
The silica abrasive system;
Product-specific FDA approvals; and
The existence of related patents.

Because the patent expired in 2013, it no longer supports a royalty base or exclusionary valuation in the United States.

Key Takeaways

U.S. Patent 5,538,715 covers dentifrices designed to improve delivery and retention of antibacterial agents on teeth and gum surfaces.
Claim 1 is the broadest claim because it covers a functional class of delivery and retention enhancers.
Claim 2 focuses on anionic maleic acid or maleic anhydride copolymers.
Claims 3-5 narrow the copolymer to methyl vinyl ether systems, specific molecular-weight ranges, concentrations, and a preferred average molecular weight of about 70,000.
Claim 16 directly targets triclosan, the copolymer, and propylene glycol.
The patent expired in 2013 and does not create current U.S. exclusivity.
The claims are composition claims. They do not cover manufacturing methods, packaging, or standalone methods of treating gingivitis.
Triclosan toothpaste is a small-molecule oral-care product, so biosimilar analysis is not applicable.
Current commercial risk would arise from later patents, regulatory status, trade secrets, or foreign rights, not from Patent 5,538,715 itself.

FAQs

Does Patent 5,538,715 cover all triclosan toothpaste?

No. The product must also satisfy the claimed vehicle, silica polishing-agent, concentration, solubilizer, and delivery-enhancer limitations. Claim 16 is specifically directed to triclosan combined with the claimed maleic acid or maleic anhydride-methyl vinyl ether copolymer and propylene glycol.

Can a toothpaste avoid the patent by replacing propylene glycol?

Claims 1 and 2 list a broader solubilizer category, and claim 13 lists alternatives such as dipropylene glycol, hexylene glycol, glycerol tristearate, and benzyl benzoate. Replacing propylene glycol avoids claim 14 and part of claim 16, but it does not automatically avoid claims 1, 2, or 13.

Does a non-silica toothpaste avoid the patent?

A formulation without the claimed siliceous polishing agent has a strong position against claims 1, 2, and 16 because those claims expressly require a siliceous polishing agent in the stated concentration range.

Does the patent cover a copolymer with a different comonomer?

A different comonomer may avoid claims 3-5 and 16, but claim 2 covers a broader copolymer of maleic acid or anhydride with another ethylenically unsaturated polymerizable monomer. Claim 1 may also remain relevant if the alternative polymer satisfies its functional-group and delivery/retention limitations.

Can this expired patent block a generic launch?

No. An expired U.S. patent cannot independently block launch or support a current Paragraph IV stay. A generic or follow-on product could still face separate, unexpired patents, FDA requirements, or regulatory exclusivity associated with the referenced product.

Was this a biologic or biosimilar patent?

No. The patent concerns a small-molecule antibacterial dentifrice formulation. Biosimilar approval pathways do not apply.

References

U.S. Patent No. 5,538,715. (1996). Antibacterial dentifrice compositions. United States Patent and Trademark Office.
United States Patent and Trademark Office. (2023). Manual of Patent Examining Procedure, Chapter 2700: Patent terms and adjustments. https://www.uspto.gov/web/offices/pac/mpep/mpep-2700.html
U.S. Food and Drug Administration. (2016). Safety and effectiveness of consumer antiseptic washes; topical antimicrobial drug products for over-the-counter human use. Federal Register.
U.S. Food and Drug Administration. (2019). FDA grants marketing authorization for Colgate Total toothpaste. FDA.

Country	Patent Number	Estimated Expiration	Supplementary Protection Certificate	SPC Country	SPC Expiration
Argentina	243371	⤷ Start Trial
Argentina	244259	⤷ Start Trial
Austria	119764	⤷ Start Trial
Austria	138557	⤷ Start Trial
Austria	150291	⤷ Start Trial
Austria	157533	⤷ Start Trial
Austria	207731	⤷ Start Trial
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Summary for Patent: 5,538,715