What if bee propolis has struggled in oral care not because it does not work, but because formulation and variability change the outcome?

In this episode of Dental Formulator’s Playbook, Dr. Rob and co-host Tami explore why bee propolis has been “promising but niche” in oral care for years, and what might finally be changing. They break down what propolis is made of, why its resins and prenylated flavonoids matter, and how the source of propolis can change everything. Then they walk through new clinical research, including studies on Brazilian green propolis in toothpaste for gingivitis and periodontal support, what the results actually showed, and where study design still leaves unanswered questions. Along the way, they highlight a surprising history lesson on “mad honey,” and why formulation details and controls matter as much as the headline claim.

About the Hosts

Dr. Rob is an independent scientist with deep expertise in oral care formulation science, microbiology models, and product performance testing.

Tami is Dr. Rob’s co-host, helping translate complex chemistry and clinical research into practical takeaways for real-world oral care.

Key Topics Covered

1. Why bee propolis has had limited commercial success despite years of hype
2. What propolis is made of: resins, lipids and waxes, essential oils, pollen, and flavonoids
3. Why propolis varies by geography and plant source, and why that matters for outcomes
4. The purpose of propolis in the hive: structure, protection, and antibacterial defense
5. Why oral “pathogens” are often already present, and the goal is balance, not scorched earth
6. Gingivitis vs periodontitis: what’s reversible, what escalates, and what measurements mean
7. Why testing on one ingredient may offer promising data, but often fails when moved into toothpaste and mouthwash systems
8. New clinical study: Brazilian green propolis extract in toothpaste, what improved and what did not
9. Why study duration matters, and why 2 weeks can be misleading for long-term benefit
10. Second clinical study: periodontal therapy support, pocket depth trends, saliva pH shifts
11. A critical nuance: when ethanol extracts are used, what is propolis vs what is ethanol effect
12. “Mad honey” from rhododendron nectar, and why natural products can carry real risks

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

🌐 Website: customdentalformulations.com

Robert L. Karlinsey, PhD

Google Scholar Profile

What if one of the most promising antimicrobial ingredients for toothpaste came from the same plant used to preserve beer?

In this episode of Dental Formulator’s Playbook, Dr. Rob Karlinsey and co-host Tami explore an unexpected crossover between brewing science and oral care innovation. What do hops, Miller Brewing, and Procter and Gamble have to do with toothpaste? Quite a lot, it turns out. This conversation breaks down how hop compounds suppress lactobacilli in beer, why that same concept appeared in toothpaste patents decades ago, and how modern patent strategy may shape the next generation of oral care products.

Highlights and Takeaways

1. Why hops are not just about bitterness, but also act as preservatives by suppressing lactobacilli and preventing beer spoilage
2. The surprising history of Miller Brewing filing an oral care patent in 1994, including toothpaste and mouthwash formulations that never reached market
3. How hop cones are harvested and kiln dried to reduce moisture and spoilage risk
4. What hops are made of, including cellulose, proteins, fats, resins, polyphenols, essential oils, and soluble fibers
5. Why the resins, not the essential oils or fibers, are the most relevant fraction for oral care
6. How hop resins are separated into soluble and insoluble fractions, and why the soluble fraction drives antimicrobial acid activity
7. The difference between hop alpha acids and hop beta acids, and why alpha acids matter most for bitterness and bacterial control
8. Why extremely low concentrations can still be biologically active, with hop alpha acids discussed at levels as low as 0.01 percent
9. How patent claims work in practice and why claim language matters more than the length of the patent
10. Why Procter and Gamble’s patent strategy expands beyond hop acids into additional resin derived compounds
11. The growing research interest in prenylated flavonoids and how their fat-affinity influences absorption and biological behavior
12. Why antimicrobial testing often fails to translate clinically once ingredients are placed into real toothpaste formulations

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

🌐 Website: customdentalformulations.com

Robert L. Karlinsey, PhD

Google Scholar Profile

What if citric acid is not inherently good or bad, but misunderstood because formulation context is rarely explained?

In this episode of Dental Formulator’s Playbook, Dr. Rob and co-host Tami take a deep, science-first look at one of the most widely used yet misunderstood ingredients in modern products: citric acid. Building on earlier episodes that examined citric acid’s role in foods and dental erosion, this conversation explores how citric acid is made, why it appears in everything from toothpaste to skincare to cleaners, and how its chemistry changes depending on form, concentration, and context.

Dr. Rob explains the critical distinction between citric acid and citrate, why hydration state matters for formulators, and how citric acid functions as a buffer, chelator, preservative, and flavor modifier. The discussion traces citric acid’s industrial production back to early fermentation research, its historical link to penicillin scale-up through Pfizer, and its foundational role in cellular energy via the Krebs (citric acid) cycle. The episode also examines citric acid’s use in cosmetics as an alpha hydroxy acid, in household cleaners, in laboratory sample preservation, and in encapsulated food applications.

Rather than framing citric acid as “good” or “bad,” this episode emphasizes understanding concentration, buffering, formulation design, and intended use to make informed decisions across oral care, food, skincare, and consumer products.

Key Topics Covered

1. The difference between citric acid and citrate in aqueous systems
2. Why citric acid and sodium citrate behave the same once dissolved in water
3. Hydration states of raw materials (anhydrous, monohydrate, dihydrate) and why they matter for formulation accuracy
4. How citric acid functions as a buffer in pharmaceuticals and oral care products
5. Why citric acid is considered a natural ingredient despite industrial-scale production
6. Fermentation-based production of citric acid using Aspergillus niger
7. The historical link between citric acid scale-up and penicillin mass production
8. Pfizer’s role in advancing fermentation technology during World War II
9. James Currie’s 1917 research and its lasting impact on microbial production methods
10. Why fermentation is still the dominant method for producing citric acid today
11. Citric acid’s role in metabolism through the Krebs (citric acid) cycle
12. Alpha hydroxy acids (AHAs) and citric acid’s role in skincare formulations
13. Concentration differences between dental products, foods, cosmetics, and cleaners
14. Why buffering citric acid is critical in oral care and pharmaceutical products
15. Citric acid use in household cleaners, including modern low-toxicity formulations