Episode 13

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Published on:

13th Oct 2025

13: Mouthwash Exposed – The Shocking Science Behind What You’re Actually Rinsing With!

Do you really know what’s in your mouthwash—or are marketing claims rinsing away the truth?

In this episode of Dental Formulator’s Playbook, Dr. Robert L. Karlinsey and co-host Tami conduct a “formula forensics” breakdown of three mouthwash types—alcohol-based essential-oil rinses (Listerine Antiseptic), zero-alcohol cosmetic rinses, and CPC-based clinical formulations. With scientific precision, they dissect ingredient labels, debunk marketing claims, and clarify what truly makes a mouthwash effective and safe.

The episode highlights the importance of formulation strategy, regulatory compliance, and proper testing—essential insights for brands, formulators, and curious consumers alike. 

🔥 Highlights ↠

  • Preservative Panic: Not all preservatives are bad—some are nature-derived and critical for preventing microbial contamination. Dr. Rob and Tami caution against “preservative-free” claims that may hide formulation risks.
  • Mouthwash 101: The hosts review several commercial products, including Listerine Cool Mint (antiseptic & zero-alcohol versions). Legacy brands, which are inherently subject to more risk, choose to adhere to established FDA guidelines.
  • Alcohol & Essential Oil Combo: Listerine Antiseptic combines 21.6–26.9% alcohol with four FDA-approved essential oils (menthol, thymol, eucalyptol, methyl salicylate) — required together to support OTC drug claims such as “anti-gingivitis” and “anti-plaque.”
  • OTC vs. Cosmetic: The zero-alcohol variant cannot legally make therapeutic claims because it lacks the necessary actives. However, marketing language and brand trust often imply comparable benefits without violating regulations.
  • The ADA Seal: Products like Listerine Antiseptic hold the ADA Seal, granted only after two independent three-month clinical trials. The seal adds credibility but isn’t mandatory for OTC status.
  • CPC Mouthwashes: A look at a Parodontax rinse with 0.07% cetylpyridinium chloride (CPC), another FDA-approved anti-plaque active. Dr. Rob explains how flavor systems, sweeteners, and surfactants can affect CPC’s bioavailability.
  • Prescription Chlorhexidine Rinses: 0.12% chlorhexidine offers potent antimicrobial action but can be overly harsh, disrupting the oral microbiome. Recommended for short-term professional use only.
  • Game of Claims: Brands strategically layer ingredients to support or suggest efficacy. The hosts teach listeners to spot phrases like “kills 99.9% of bacteria” and determine whether such claims are backed by validated testing.
  • Preservation Systems Matter: Effective formulations often use dual-component systems (e.g., benzoic acid + sodium benzoate). Challenge testing (ISO 11930) ensures long-term microbial safety in water-based products.
  • Color & Flavor Strategy: The duo examines dyes (Green 3, Blue 1) and complex flavor blends containing terpenes or acids—key not just for taste but for product stability, consumer perception, and compliance.

 Key Takeaways

  • Look closely at labels — learn the distinction between active and inactive ingredients and what’s required to make legal claims.
  • Even cosmetic mouthwashes must be tested for safety and stability.
  • Smart formulation demands a balance of science, regulation, and consumer expectations.

📲 Connect with Dr. Rob (Robert L. Karlinsey, PhD)

🌐 Website: customdentalformulations.com

 📄 Research Profile: Robert Karlinsey on ResearchGate

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About the Podcast

Dental Formulator's Playbook
The Dental Formulator’s Playbook is where science meets strategy in the world of oral health innovation. Hosted by Dr. Rob Karlinsey, a seasoned dental researcher and independent formulator, this podcast is your behind-the-scenes pass to what really goes into creating cutting-edge dental products.

Whether you're a dentist, a dental brand, or just someone curious about how toothpaste, rinses, and other oral care products are developed, you'll find practical insights and real-world takeaways in every episode. Dr. Karlinsey keeps it straightforward and engaging—no fluff, just clear, thoughtful explanations based on years of experience in the lab and the industry.

This show is all about helping dental professionals and product developers think differently, make better decisions, and stay ahead of the curve. If you care about science, results, and doing things the right way, you're in the right place.

About your host

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Robert Karlinsey

Dr. Robert L. Karlinsey is a scientist and formulator with almost 20 years’ experience in dental research. He earned a BS in Physics (University of Scranton) and PhD in Chemical Physics (Indiana University), with postdoctoral work in physical chemistry (Indiana University). As a visiting assistant research professor at the Indiana University School of Dentistry, his research led to an impactful encounter with Dr. George Stookey, and shortly thereafter, the formation of Indiana Nanotech, LLC (now known as Custom Dental Formulations, LLC), of which he spearheaded all research and small-scale manufacturing efforts. Dr. Karlinsey is the inventor of Nanotech’s functionalized tricalcium phosphate systems, which continue to help generate over $100MM in global product sales for a major dental manufacturer. As Principal Investigator, his work has received significant funding through Federal (National Institutes of Health), State (Indiana and Texas), and industry grants and contracts. His research in patented calcium phosphate technologies continue to help generate over $100MM in global product sales. Previously, Dr. Karlinsey has served as Chief Scientific Officer at Therametric Technologies, Inc, and adjunct professor of chemistry at the University of Indianapolis.

Dr. Karlinsey addresses clients’ needs in preventive and cosmetic dentistry, including fluoride- and fluoride-free remineralization, antiplaque/gum health, whitening systems, and more. He is actively involved in clinical and laboratory research designs and performance-backed, customized oral care formulation solutions. And, whenever possible, he favors natural, nature-derived, and/or sustainably sourced ingredients