Scientific Research: Oral Care+
SCIENTIFIC RESEARCH ON THE FOLLOWING INGREDIENTS:
Zinc Citrate
Two mechanisms of oral malodor inhibition by zinc ions1
Overview: This study set out to clarify exactly how zinc ions reduce bad breath, since earlier research had proposed two competing explanations — direct chemical binding versus antibacterial action — without settling which one actually matters more.
Methods: Researchers tested the direct binding of zinc ions to gaseous hydrogen sulfide (H2S), comparing zinc against eight other metal ions (chlorides and acetates). They determined the minimum concentration of each needed to inhibit H2S volatilization using serial dilution. Separately, they tested zinc's inhibitory effect on the growth of six oral bacterial strains linked to volatile sulfur compound (VSC) production and three strains not linked to VSC production.
Results: Zinc chloride and zinc acetate, along with several other metal salts, almost entirely inhibited H2S volatilization through direct chemical binding — zinc's strength on this measure ranked behind silver, cadmium, and copper ions, but was still substantial. Separately, zinc ions also suppressed the growth of VSC-producing oral bacteria, with effects that varied by bacterial strain; Fusobacterium nucleatum was the most sensitive, suppressed at a concentration of just 0.001% zinc.
Conclusion: The authors conclude zinc ions reduce oral malodor through two distinct, independent mechanisms: direct chemical binding to gaseous H2S, and a separate antibacterial effect on the specific bacteria that produce VSCs. Both mechanisms contribute, but they are mechanistically separate — a formula could rely on the binding mechanism alone even where an antibacterial claim isn't being made.
Source: Suzuki N, Nakano Y, Watanabe T, Yoneda M, Hirofuji T, Hanioka T. Two mechanisms of oral malodor inhibition by zinc ions. Journal of Applied Oral Science. 2018;26:e20170161. PMID: 29364345.
Effects of Toothpaste Containing 2% Zinc Citrate on Gingival Health and Three Related Bacteria — A Randomized Double-Blind Study2
Overview: A human clinical trial testing whether a 2% zinc citrate toothpaste changes gum health and the abundance of specific bacteria linked to gingivitis and periodontitis, compared to a standard fluoride toothpaste.
Methods: Eleven volunteers with matched baseline oral health were randomized to a treatment group (fluoride toothpaste plus 2% zinc citrate, n=5) or a control group (fluoride toothpaste alone, n=6), used over three months. Plaque index, gingival index, and bleeding index were measured at baseline, three weeks, and three months. Dental plaque was collected from four areas of the mouth at each timepoint — 132 samples total — and analyzed by quantitative PCR to track the abundance of three bacteria: Actinobacillus actinomycetemcomitans, Porphyromonas gingivalis, and Tannerella forsythia.
Results: The zinc citrate group showed improved gingival health scores over the study period, along with a reduction in the total abundance of the three targeted bacteria in dental plaque, while plaque index itself was largely unchanged between groups.
Conclusion: The authors conclude that toothpaste containing 2% zinc citrate persistently improves gingival health and reduces the presence of bacteria linked to gingivitis and periodontitis, proposing this reflects a direct effect of zinc on these specific bacterial species in the plaque.
Note: this study used zinc citrate at a much higher, topically-applied concentration (2% in toothpaste, held in direct contact with gum tissue via brushing) than the amount included in Oral Care+, which is ingested with food rather than applied directly to the gumline.
Source: Zhou Y, Zhou Y, et al. Effects of Toothpaste Containing 2% Zinc Citrate on Gingival Health and Three Related Bacteria — A Randomized Double-Blind Study. Clinical and Experimental Dental Research. 2024;10:e70020. PMID: 39497343.
Sodium Bicarbonate & Calcium Carbonate
Effect of baking soda in dentifrices on plaque removal3
Overview: This paper reviews and reports on how baking soda (sodium bicarbonate), used as an abrasive in toothpaste, compares to non-baking-soda dentifrices for physically removing plaque.
Methods: The study measured whole-mouth plaque scores at five oral sites after brushing with a baking-soda-containing dentifrice versus several non-baking-soda dentifrices, across a series of trials.
Results: Brushing with a baking soda dentifrice significantly reduced whole-mouth plaque scores by 14% to 71% compared to non-baking-soda dentifrices (p < .005), with a dose-response relationship — higher baking soda concentration produced greater plaque reduction. The authors proposed three explanations: baking soda's larger crystal size enhances physical displacement of plaque compared to other abrasives; dissolving baking soda may physically disrupt the polysaccharide matrix that holds plaque together; and bicarbonate ions may interfere with bacterial attachment to the tooth surface.
Conclusion: The main mode of action for dentifrice abrasives, including baking soda and calcium carbonate (both classified under "carbonate type" abrasives), is mechanical abrasion — a physical process of displacing and disrupting plaque through friction, distinct from chemical or antibacterial action.
Source: Hara AT, González-Cabezas C, Creeth J, Parmar M, Eckert GJ, Zero DT. Effect of baking soda in dentifrices on plaque removal. Journal of the American Dental Association. 2017;148(11S):S20-S26.
Abrasion, polishing, and stain removal characteristics of various commercial dentifrices in vitro4
Overview: A lab-based comparison of the physical cleaning characteristics of toothpastes formulated with different abrasive systems, including calcium carbonate, to establish how abrasive particle type and size relate to plaque and stain removal versus enamel wear.
Findings: Calcium carbonate (CaCO3) is classified as a mild-to-moderate mechanical abrasive commonly used in oral care products. Its cleaning action depends heavily on particle size and shape — larger, more angular (rhombohedral) particles clean more aggressively but risk higher abrasivity, while smaller, rounder particles clean more gently. Toothpaste abrasivity is measured using RDA (Relative Dentin Abrasivity); products carrying the ADA Seal must have an RDA of 250 or below. Properly formulated calcium carbonate provides mechanical removal of plaque and surface stains while remaining within safe abrasivity limits.
Conclusion: Calcium carbonate's cleaning benefit in oral care comes specifically from mechanical abrasion during brushing or chewing contact, not from any chemical or antibacterial action — its performance is a function of particle size, shape, and concentration within the overall formulation.
Source: Schemehorn BR, Moore MH, Putt MS. Abrasion, polishing, and stain removal characteristics of various commercial dentifrices in vitro. J Clin Dent. 2011;22(1):11-8. PMID: 21290981.
Coconut Powder
Effect of coconut oil in plaque related gingivitis — A preliminary report5
Overview: A prospective clinical study testing whether "oil pulling" (swishing oil in the mouth) with coconut oil — which is roughly 45-50% lauric acid by composition — reduces plaque and plaque-related gingivitis in adolescents.
Methods: 60 adolescents aged 16-18 with plaque-induced gingivitis added coconut oil pulling to their oral hygiene routine daily for 30 days. Plaque and gingival indices were assessed at baseline, day 1, 7, 15, and 30, and analyzed using a paired t-test.
Results: A statistically significant decrease in both plaque and gingival index scores was observed starting at day 7, with scores continuing to decrease through the full 30-day study period.
Conclusion: The authors conclude coconut oil pulling could be an effective adjunct procedure for decreasing plaque formation and plaque-induced gingivitis, attributing the effect to lauric acid's documented anti-inflammatory and antimicrobial properties.
Note: this study used coconut oil as a concentrated oil swished directly in the mouth for extended contact time — a very different delivery method and dose than the coconut powder (250 mg per serving) included in Oral Care+, which is ingested with food.
Source: Peedikayil FC, Sreenivasan P, Narayanan A. Effect of coconut oil in plaque related gingivitis — A preliminary report. Nigerian Medical Journal. 2015;56(2):143-147. PMID: 25838632.
Anti-inflammatory and antimicrobial efficacy of coconut oil for periodontal pathogens: a triple-blind randomized clinical trial6
Overview: The first randomized clinical trial to examine coconut oil's effect on the oral microbiome and inflammatory markers specifically in patients diagnosed with periodontitis, comparing it against the gold-standard antiseptic chlorhexidine and a placebo.
Methods: 30 participants with periodontitis were randomized into three groups: coconut oil, chlorhexidine, or placebo. The coconut oil used was selected for its high lauric acid content (47.92%) after gas chromatography analysis of four commercial oils. Participants rinsed with 5 mL for 10 minutes nightly after brushing (versus just 1 minute for the chlorhexidine and placebo groups). Saliva and gingival crevicular fluid were sampled before treatment, one month after, and one month after standard periodontal therapy. Bacterial DNA was sequenced via 16S rRNA gene analysis, and inflammatory markers (IL-6, TNF-α) were measured.
Results: Coconut oil rinsing significantly reduced bacterial load both above and below the gumline, specifically targeting two bacterial families associated with periodontal disease progression. It also reduced levels of the inflammatory markers IL-6 and TNF-α, performing comparably to chlorhexidine despite requiring a much longer contact time to achieve similar effects.
Conclusion: The authors conclude coconut oil shows potential as a natural adjunct to standard periodontal therapy, reducing pathogenic bacteria and inflammation, and could serve as an alternative to chlorhexidine that avoids chlorhexidine's known side effects like dental staining.
Note: as with the study above, this trial used concentrated coconut oil in prolonged direct contact with affected gum tissue — a different format and exposure than a small amount of coconut powder ingested with food.
Source: [Authors], et al. Anti-inflammatory and antimicrobial efficacy of coconut oil for periodontal pathogens: a triple-blind randomized clinical trial. Clinical Oral Investigations. 2025. DOI: 10.1007/s00784-025-06267-8.
Kelp (Laminaria / Ascophyllum)
Effects of Edible Treats Containing Ascophyllum nodosum on the Oral Health of Dogs: A Double-Blind, Randomized, Placebo-Controlled Single-Center Study7
Overview: The primary clinical trial behind the use of brown seaweed (Ascophyllum nodosum, closely related to the Laminaria japonica used in Oral Care+) in canine dental products, testing its effect on plaque, calculus, and related oral health measures in real dogs over 90 days.
Methods: 60 client-owned dogs across five small breeds (Japanese Chin, Miniature Schnauzer, Chihuahua, Pomeranian, West Highland White Terrier) underwent professional dental cleaning under anesthesia, then were randomized to receive daily edible treats containing A. nodosum or a placebo, dosed to bodyweight. Clinical assessments — plaque index, calculus index, oral health index, gingival bleeding index, and volatile sulfur compound (VSC) concentration — were performed under sedation at 30, 60, and 90 days.
Results: Dogs receiving A. nodosum showed significantly better scores than the placebo group across plaque index, calculus index, and VSC concentration at all three timepoints. Both groups saw plaque and calculus increase after the initial professional cleaning wore off, but the increase was measurably slower in the seaweed-supplemented dogs.
Conclusion: The authors conclude that daily A. nodosum supplementation efficiently decreased the rate of plaque and calculus accumulation in dogs compared to placebo, over a 90-day period following a professional cleaning baseline.
Source: Gawor JP, Jank M, Jodkowska K, Klim E, Svensson UK. Effects of Edible Treats Containing Ascophyllum nodosum on the Oral Health of Dogs: A Double-Blind, Randomized, Placebo-Controlled Single-Center Study. Frontiers in Veterinary Science. 2018;5:168.
Ascophyllum nodosum as a nutrient supporting oral health in dogs and cats: a review8
Overview: A review examining what's actually known — and not known — about how Ascophyllum nodosum affects oral health in dogs and cats, following up on the clinical trial results above with a look at proposed mechanisms.
Findings: The review confirms A. nodosum has been shown to reduce both calculus and plaque accumulation in dogs and cats across multiple clinical trials assessed to Veterinary Oral Health Council standards. Critically, the review states the exact mechanism of action "remains unclear" — it is not a mechanical or abrasive action. The earliest metabolomic data suggests A. nodosum changes the chemical composition of dog saliva after oral administration, and that this altered saliva composition may be what interferes with plaque and calculus formation, rather than any direct physical or antibacterial action in the mouth. The review also notes A. nodosum's preventive effect is strongest in powder form, compared to dental treats or mixing into dry food, and that it works preventively — it does not remove plaque or calculus that has already formed.
Conclusion: The authors conclude A. nodosum shows a genuine, clinically-demonstrated preventive effect on plaque and calculus buildup in dogs and cats, but that researchers still don't have a confirmed explanation for the underlying mechanism, beyond early evidence that it works through changes to saliva chemistry rather than through mechanical or antibacterial means.
Source: Gawor JP, Jank M. Ascophyllum nodosum as a nutrient supporting oral health in dogs and cats: a review. Polish Journal of Veterinary Sciences. 2023;26(3):511-520. PMID: 37727971.
Cranberry Extract
Influence of Cranberry Proanthocyanidins on Formation of Biofilms by Streptococcus mutans on Saliva-Coated Apatitic Surface and on Dental Caries Development in vivo9
Overview: This study investigated whether purified cranberry proanthocyanidins (PAC) — the compound class behind cranberry's dental research — actually reduce biofilm formation by Streptococcus mutans, the primary bacterium responsible for dental caries, both in a lab model and in live animals.
Methods: Researchers applied a highly purified, chemically-defined cranberry PAC fraction topically (twice daily, 60-second exposure) to S. mutans biofilms grown on a saliva-coated hydroxyapatite surface — a model that mimics the tooth surface. Separately, they tested cranberry PAC's effect on dental caries development directly in Sprague-Dawley rats, and examined specific PAC molecule sizes (from monomers to high-molecular-weight oligomers) for their ability to inhibit glucosyltransferase (GtfB), the bacterial enzyme responsible for building the sticky biofilm matrix.
Results: Cranberry PAC treatment produced significantly less biofilm biomass and fewer insoluble polysaccharides than the vehicle control (p < 0.05). In rats, PAC treatment significantly reduced both the incidence and severity of dental caries compared to control. Specific A-type PAC oligomers (dimers through dodecamers) were identified as the most effective at blocking GtfB enzyme activity and interfering with the bacteria's sugar metabolism.
Conclusion: The authors conclude cranberry PAC reduces S. mutans biofilm formation and dental caries development, with the effect attributed to specific bioactive PAC compounds interfering with the bacterial enzymes and sugar-processing machinery that build cavity-causing biofilm.
Source: Koo H, Duarte S, Murata RM, Scott-Anne K, Gregoire S, Watson GE, Singh AP, Vorsa N. Influence of Cranberry Proanthocyanidins on Formation of Biofilms by Streptococcus mutans on Saliva-Coated Apatitic Surface and on Dental Caries Development in vivo. Caries Research. 2010;44(2):116-126.
Cranberry Flavonoids Modulate Cariogenic Properties of Mixed-Species Biofilm through Exopolysaccharides-Matrix Disruption10
Overview: A follow-up mechanistic study looking specifically at how cranberry flavonoids (including PACs and myricetin) physically weaken the structural matrix that holds cavity-causing biofilm together, without necessarily killing the bacteria themselves.
Methods: Researchers applied a combination of cranberry PAC oligomers and myricetin topically, twice daily, to a mixed-species biofilm grown under conditions designed to promote cavities. They measured the biofilm's structure, its mechanical stability under physical shear stress, and the pH at the biofilm-tooth interface.
Results: Cranberry flavonoid treatment reduced the insoluble exopolysaccharide (EPS) content of the biofilm by more than 80% compared to vehicle control. The treated biofilm's 3D structure was severely compromised and failed to properly form microcolonies. Mechanically, nearly 90% of the cranberry-treated biofilm was removed under a standardized shear stress test, compared to only 36% removal in untreated biofilm. The treated biofilm also maintained a significantly higher (less acidic) pH at the tooth surface.
Conclusion: The authors conclude cranberry flavonoids disrupt the structural matrix that holds cariogenic biofilm together and weaken its attachment to the tooth surface, without directly killing the bacteria — a mechanism distinct from traditional antibacterial action.
Source: Kim D, Hwang G, Liu Y, Wang Y, Singh AP, Vorsa N, Koo H. Cranberry Flavonoids Modulate Cariogenic Properties of Mixed-Species Biofilm through Exopolysaccharides-Matrix Disruption. PLOS ONE. 2015;10(12):e0145844. PMID: 26713438.
Organic Matcha
Determination of catechins in matcha green tea by micellar electrokinetic chromatography11
Overview: This is the original study behind the widely-repeated claim that matcha delivers dramatically more antioxidant catechins than regular green tea. It's worth reading directly, since the claim gets exaggerated a lot in secondary sources.
Methods: Researchers developed a chromatography method to precisely measure five catechins and caffeine in matcha, then compared catechin concentrations (on a mg catechin per gram of dry leaf basis) between matcha and one specific commercial green tea product.
Results: EGCG concentration in matcha was measured at 137 times greater than in the specific comparison tea used (a particular commercial green tea product), and at least three times higher than the largest EGCG values reported elsewhere in the scientific literature for green tea generally.
Conclusion: The authors conclude matcha delivers substantially more catechin intake than steeped green tea, since matcha involves consuming the whole tea leaf rather than steeping and discarding it.
Important accuracy note: the widely-circulated "137x" figure specifically compares matcha to one particular tea product, not to green tea as a category — more recent, broader comparisons across multiple commercial green teas (see Plant Foods for Human Nutrition, 2023) put the realistic difference closer to roughly 2-3x, which is the range Oral Care+'s marketing claim is based on.
Source: Weiss DJ, Anderton CR. Determination of catechins in matcha green tea by micellar electrokinetic chromatography. Journal of Chromatography A. 2003;1011(1-2):173-180. PMID: 14518774.
Reduced Dental Plaque Formation in Dogs Drinking a Solution Containing Natural Antimicrobial Herbal Enzymes and Organic Matcha Green Tea12
Overview: An exploratory, multicenter clinical study testing whether a water-additive formula reduced the rate of plaque formation in dogs. Matcha green tea was one of five active ingredients in the tested formula, alongside plant-derived enzymes, cultured dextrose, sodium bicarbonate, and ascorbic acid.
Methods: Healthy dogs of varying breeds, sex, and age were non-randomly assigned to a treatment group (drinking only water with the formula dissolved in it) or a control group (normal household water) for 28 days. All teeth were professionally cleaned and assessed at baseline. Plaque index, plaque thickness, gingivitis, and breath freshness were assessed on days 14, 21, and 28.
Results: The multicenter study confirmed the hypothesis that the formula reduced the rate of plaque formation on dogs' teeth compared to control over the 28-day period.
Conclusion: The authors conclude this combination formula, including organic matcha, reduced dental plaque formation in dogs when delivered via drinking water.
Note: this study tested matcha as one part of a five-ingredient combination formula in drinking water, not matcha in isolation, so the plaque-reduction result can't be attributed to matcha alone — Oral Care+'s claim for matcha is limited to its antioxidant/EGCG content, sourced instead to the Weiss & Anderton study above.
Source: Lindinger M, et al. Reduced Dental Plaque Formation in Dogs Drinking a Solution Containing Natural Antimicrobial Herbal Enzymes and Organic Matcha Green Tea. Scientifica. 2016;2016:2183623. PMID: 27867678.
Live Probiotic Trio
An Assessment of the Stability of the Canine Oral Microbiota After Probiotic Administration in Healthy Dogs Over Time13
Overview: A real-world canine study testing whether daily oral probiotic administration — delivered the same way Oral Care+ is used, as a powder top-dressed on food — actually changes the oral microbiota of healthy working dogs over time.
Methods: 14 dogs in training at a veterinary working-dog center were assigned to a probiotic (Fortiflora®) or control group. Probiotic dogs received the product top-dressed on their midday feeding daily. All dogs were sampled weekly via oral swabs over seven weeks, with 16S rRNA sequencing used to characterize oral bacterial communities.
Results: Contrary to the study's hypothesis, probiotic administration did not significantly alter the composition of the dogs' oral microbiota compared to control. This contrasted with prior research on a different probiotic blend (containing Streptococcus thermophilus, Lactobacillus plantarum, and Lactobacillus rhamnosus), which had found a reduction in infectious microbes when administered the same way.
Conclusion: The authors conclude that probiotic effects on the canine oral microbiota may depend heavily on which specific bacterial strains are used — this particular probiotic did not measurably shift oral bacterial composition, while a different strain blend in earlier research did. This underscores that probiotic effects on the mouth are strain-specific and shouldn't be assumed to generalize across products.
Source: Bell SE, Nash AK, Zanghi BM, Otto CM, Perry EB. An Assessment of the Stability of the Canine Oral Microbiota After Probiotic Administration in Healthy Dogs Over Time. Frontiers in Veterinary Science. 2020;7:616.
Impact of Oral Probiotics on Dental Biofilm Bacteria in Dogs14
Overview: A lab-based study testing whether specific probiotic strains — including Lactobacillus casei DG, the same species used in Oral Care+ — have direct effects on bacteria isolated from the dental plaque of dogs with dental disease.
Methods: Researchers isolated bacteria from the genera Staphylococcus, Streptococcus, Pasteurella, and Neisseria from the supragingival dental plaque of dogs of varying breed, age, sex, weight, and diet. Using an agar overlay method, they tested the antimicrobial activity of L. casei DG alone, and separately a mixed culture of L. acidophilus LA-5 and Bifidobacterium bifidum BB-12, against the isolated pathogenic species.
Results: L. casei DG showed a bactericidal effect against all analyzed species from all four bacterial genera after 24 hours of incubation. The mixed L. acidophilus/Bifidobacterium culture had no bactericidal effect on the Staphylococcus and Streptococcus species tested (which were resistant to it), but did show a bacteriostatic (growth-inhibiting, rather than bacteria-killing) effect against several Pasteurella and Neisseria species.
Conclusion: The authors conclude this in vitro work demonstrates real antimicrobial potential for probiotics against dog dental plaque bacteria, with L. casei DG showing the strongest, broadest effect of the strains tested, while noting these are lab-dish findings that haven't yet been confirmed in a live clinical trial in dogs.
Note: full journal and publication details for this paper could not be independently verified beyond its posting on ResearchGate by researchers affiliated with the University of Veterinary Medicine and Pharmacy in Košice, Slovak Republic — flagging this as a lower-certainty source than the peer-reviewed journal citations elsewhere in this document.
Source: [Authors affiliated with UVMP Košice]. Impact of Oral Probiotics on Dental Biofilm Bacteria in Dogs. ~2019.
REFERENCES
- https://pmc.ncbi.nlm.nih.gov/articles/PMC5777415/
- https://onlinelibrary.wiley.com/doi/10.1002/cre2.70020
- https://jada.ada.org/article/S0002-8177(17)30809-7/fulltext
- https://pubmed.ncbi.nlm.nih.gov/21290981/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC4382606/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC11909057/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC6080642/
- https://pubmed.ncbi.nlm.nih.gov/37727971/
- https://karger.com/cre/article/44/2/116/85230
- https://pmc.ncbi.nlm.nih.gov/articles/PMC4699891/
- https://pubmed.ncbi.nlm.nih.gov/14518774/
- https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5102751/
- https://pmc.ncbi.nlm.nih.gov/articles/PMC7517700/
- https://www.researchgate.net/publication/337732408_IMPACT_OF_ORAL_PROBIOTICS_ON_DENTAL_BIOFILM_BACTERIA_IN_DOGS