Mark Burhenne
Dr. Mark Burhenne is a commentator on dental and oral health. His work and discussions focus on the oral microbiome and how bacteria in the mouth influence the digestive system and overall health.
31 claims checked on air: 2 context 1 contradicted 7 overstated 16 supported 5 unverified
What they said on air - supported
The oral microbiome is second only to the gut microbiome in both diversity and size within the human body.
"The gut microbiome, of course, is the big one, but the oral microbiome is second in diversity and in size" (said at 0:04:05)
Scientific consensus from large-scale human microbiome profiling studies establishes that the gastrointestinal tract harbors the largest and most diverse microbial community in the human body, followed by the oral cavity, which contains hundreds of distinct microbial species across various micro-niches.
Porphyromonas gingivalis has been detected in human brain tissue and drives gum disease.
"P. gingivalis has been found in the brain and it's in the mouth and it's the driver of gum disease." (said at 0:05:23)
Porphyromonas gingivalis is widely recognized as a keystone bacterial pathogen driving chronic periodontitis (gum disease) and has been identified in human post-mortem brain tissue, along with its toxic proteases (gingipains).
Having gum disease was a risk factor for severe infection or death from COVID-19.
"And for example, during COVID, if you had gum disease, that was a risk factor for getting a severe infection or even death from COVID." (said at 0:09:45)
Observational studies and meta-analyses show that pre-existing periodontitis (gum disease) is significantly associated with an increased risk of severe COVID-19 outcomes, including intensive care unit (ICU) admission, need for assisted ventilation, severe disease course, and mortality. Because the available evidence consists of observational case-control and cohort designs with potential confounding and methodological heterogeneity, the certainty of evidence is graded as low.
- supports: Association between periodontitis and severity of COVID-19 infection: A case-control study… (Journal of clinical periodontology 2021) · cited 389x in the literature
"After adjusting for potential confounders, periodontitis was associated with COVID-19 complication including death (OR = 8.81, 95% CI 1.00-77.7), ICU admission (OR = 3.54, 95% CI 1.39-9.05) and need for assisted ventilation (OR = 4.57, 95% CI 1.19-17.4)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: The impact of periodontal disease on the clinical outcomes of COVID-19: A systematic revie… (BMC oral health 2023) · cited 15x in the literature
"The pooled data found a significant association between PD and COVID-19 outcomes: more severe symptoms (OR = 6.95, P = 0.0008), ICU admissions (OR = 3.15, P = 0.0001), and mortality (OR = 1.92, P = 0.21). Additionally, compared to mild PD, severe PD was significantly associated with higher risks of severe COVID-19 outcomes: severe symptoms (P = 0.02); ICU admission (P = 0.0001); and higher mortality rates (P = 0.0001)." (abstract, results, passage verified)
pubmedfull study (doi)
Porphyromonas gingivalis excretes a substance called gingipain, which can travel to the brain.
"the P. gingivalis bug will get to the brain. It will literally—it'll excrete the substance called the gingipain." (said at 0:12:30)
The claim is supported by published literature. Porphyromonas gingivalis is an oral pathogen that secretes cysteine endopeptidases known as gingipains (such as RgpA, RgpB, and Kgp). Both P. gingivalis bacteria and their secreted gingipains have been identified in the brain tissue of humans with neurodegenerative disorders such as Alzheimer's disease and Parkinson's disease, as well as in experimental animal models following oral infection.
- supports: Porphyromonas gingivalis in Alzheimer's disease brains: Evidence for disease causation and… (Science advances 2019) · cited 1906x in the literature
"Porphyromonas gingivalis , the keystone pathogen in chronic periodontitis, was identified in the brain of Alzheimer's disease patients. Toxic proteases from the bacterium called gingipains were also identified in the brain of Alzheimer's patients, and levels correlated with tau and ubiquitin pathology. Oral P. gingivalis infection in mice resulted in brain colonization and increased production of Aβ 1-42 , a component of amyloid plaques." (abstract, passage verified)
pubmedfull study (doi) - supports: Gingipains as macromolecular mediators at the periodontal-brain interface: Mechanistic, di… (International journal of biological macromolecules 2026)
"Chronic periodontitis, driven by Porphyromonas gingivalis, has emerged as a modifiable risk factor for the two most prevalent neurodegenerative disorders includingAlzheimer's disease (AD) and Parkinson's disease (PD), through systemic dissemination of its signature cysteine proteases, gingipains (RgpA, RgpB, Kgp)... gingipains have been detected in a high proportion (>85-90%) of postmortem AD/PD brains, correlating with tau/α-synuclein pathology, neuroinflammation, and neuronal loss." (abstract, passage verified)
pubmedfull study (doi)
Commensal oral biofilms facilitate the remineralization of demineralized tooth enamel by processing minerals from saliva.
"one of the functions of the biofilm, and again, we're talking about plaque, that's a term that we used to use, um this is a proteoglycan layer... one of the functions of the biofilm is to help remineralize demineralizing areas of the teeth. And that essentially is reversing small cavities as they are happening." (said at 0:26:00)
Dental biofilm and its fluid phase, alongside the acquired pellicle and saliva, play a direct role in the continuous dynamic equilibrium of tooth enamel demineralization and remineralization. Under non-acidic conditions, saliva and biofilm fluid are supersaturated with calcium and phosphate ions relative to tooth hydroxyapatite, driving mineral precipitation back into early subsurface carious lesions (initial enamel demineralization). While dental plaque can drive demineralization when acidogenic bacteria ferment dietary carbohydrates, the commensal biofilm and biofilm fluid serve as reservoirs for salivary ions and fluoride that facilitate the natural remineralization and reversal of early non-cavitated lesions.
- supports: Chapter 5.1: Physicochemical Interactions between Enamel and Oral Fluids. (Monographs in oral science 2023) · cited 5x in the literature
"Saliva, and even the biofilm fluid, is supersaturated with calcium (Ca2+) and phosphate (PO43-) in relation to enamel solubility, and thus the natural tendency of enamel is to gain mineral, conferring saliva with a remineralizing property." (abstract, results, passage verified)
pubmedfull study (doi) - supports: The Remineralization of Enamel from Saliva: A Chemical Perspective. (Dentistry journal 2024) · cited 49x in the literature
"In principle, early erosions (demineralization) induced by acidic beverages and foods as well as initial caries lesions can be covered and remineralized by the deposition of calcium phosphate, i.e., tooth mineral. This remineralization effect is characterized by the presence of calcium and phosphate ions in saliva that form hydroxyapatite on the enamel surface." (abstract, results, passage verified)
pubmedfull study (doi)
Oral bacteria on the back of the tongue convert dietary nitrates from foods like beets into nitric oxide.
"There are bacteria on the back of the tongue, part of the oral microbiome, of course, that actually when they see a uh like a beet or a high nitrate food, they will produce NO." (said at 0:29:15)
Dietary inorganic nitrate from foods such as beetroot and green leafy vegetables is concentrated in saliva and reduced by symbiotic nitrate-reducing bacteria residing predominantly on the tongue dorsum and in saliva. These oral bacteria express nitrate reductase enzymes (which humans lack) that reduce nitrate (NO3-) to nitrite (NO2-). When swallowed, salivary nitrite is converted into nitric oxide (NO) in the acidic gastric environment and systemically in tissues and blood via the enterosalivary nitrate-nitrite-nitric oxide pathway. In addition, some oral bacterial taxa can directly reduce nitrite to NO via denitrification pathways.
- supports: Metagenomic analysis of nitrate-reducing bacteria in the oral cavity: implications for nit… (PloS one 2014) · cited 270x in the literature
"The recently described entero-salivary nitrate-nitrite-nitric oxide pathway has been shown to provide bioactive NO from dietary nitrate sources. Interestingly, this pathway is dependent upon oral nitrate-reducing bacteria, since humans lack this enzyme activity. This pathway appears to represent a newly recognized symbiosis between oral nitrate-reducing bacteria and their human hosts in which the bacteria provide nitrite and nitric oxide from nitrate reduction." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Pathways Linking Oral Bacteria, Nitric Oxide Metabolism, and Health. (Journal of dental research 2022) · cited 61x in the literature
"Nitrate-reducing oral bacteria have gained a lot of interest due to their involvement in nitric oxide (NO) synthesis and its important cardiometabolic outcomes." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Localisation of nitrate-reducing and highly abundant microbial communities in the oral cav… (PloS one 2023) · cited 14x in the literature
"The nitrate (NO3-) reducing bacteria resident in the oral cavity have been implicated as key mediators of nitric oxide (NO) homeostasis and human health. NO3--reducing oral bacteria reduce inorganic dietary NO3- to nitrite (NO2-) via the NO3--NO2--NO pathway." (abstract, results, passage verified)
pubmedfull study (doi)
Swishing with disinfecting mouthwash twice a day elevates blood pressure within two to three days by compromising nitric oxide production.
"so, you you swish with mouthwash twice a day. These are studies from 2005 and and even recent ones. I just read a new one that popped out yesterday. And it actually elevates your blood pressure within two to three days. And obviously, that is because the NO production is is uh compromised." (said at 0:30:38)
Human clinical trials support the claim. Oral bacteria in the mouth reduce salivary nitrate into nitrite, which enters the bloodstream and serves as a vital substrate for systemic nitric oxide (NO) generation and vasodilation. When healthy individuals use a strong antiseptic mouthwash (such as chlorhexidine) twice daily, the oral nitrate-reducing microbiome is suppressed, reducing plasma nitrite levels and causing a measurable rise in systolic and diastolic blood pressure within 1 to 3 days.
Studies demonstrate that individuals with gum disease are likely to have erectile dysfunction.
"there are a lot of good studies uh that if you have gum disease, you you are likely to have erectile dysfunction. Again, that is that is directly linked to the condition and the state of the oral microbiome." (said at 0:32:58)
Multiple systematic reviews and meta-analyses of observational studies demonstrate a statistically significant association between periodontal disease and erectile dysfunction, with affected individuals having roughly 2 to 3 times higher odds of erectile dysfunction compared to those without gum disease. Because the underlying evidence base consists primarily of observational (case-control, cross-sectional, and cohort) studies with substantial statistical heterogeneity, the GRADE certainty is rated as low.
- supports: The association between chronic periodontitis and vasculogenic erectile dysfunction: a sys… (Journal of clinical periodontology 2016) · cited 25x in the literature
"Based on random effects meta-analysis, a significant association between CP and ED was identified (OR = 3.07, 95% CI: 1.87-5.05, p < 0.001)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Chronic periodontitis and the risk of erectile dysfunction: a systematic review and meta-a… (International journal of impotence research 2017) · cited 24x in the literature
"Based on the random-effects model, analyses of all studies showed that CP was associated with an increased risk of ED (OR=2.28, 95% CI: 1.50-3.48)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: The Association Between Periodontitis and Erectile Dysfunction: A Systematic Review and Me… (American journal of men's health 2021) · cited 12x in the literature
"Based on the random effects model, periodontitis was associated with an increased risk of ED (OR = 2.56, 95% CI: 1.70-3.85) as compared with the non-periodontitis individuals. The findings were statistically significant with a p < .0001." (abstract, results, passage verified)
pubmedfull study (doi)
Hydroxyapatite dental remineralization technology was developed by NASA and has been used in commercial oral care products in Japan for 40 years.
"Japan's been using wonderful uh products developed by NASA uh coincidentally for 40 years. And and that stuff now is slowly becoming available in the US." (said at 0:36:27)
Hydroxyapatite oral care technology was originally conceived and patented by NASA in the 1970s to help repair astronauts' bone and tooth mineral loss in zero gravity environments. In 1978, the Japanese company Sangi Co., Ltd. acquired the patent rights from NASA and subsequently launched the world's first hydroxyapatite remineralizing toothpaste (Apagard / Apadent) in Japan in 1980, followed by Japanese government approval as an anti-caries agent in 1993. This represents roughly four decades of commercial use in Japan before gaining wider availability and regulatory adoption in North America and Europe.
Sodium lauryl sulfate (SLS) breaks down the lipid layer in oral mucosal cells and crosses into the blood supply, as shown in rat studies.
"And what it does though is it affects it can literally break down the lipid layer in a cell. That's bad. It can actually cross over into the blood supply uh through the oral mucosa. We've got plenty of rat studies that that show and demonstrate that." (said at 0:40:04)
Animal studies in rats demonstrate that sodium lauryl sulfate (SLS) damages the oral mucosal permeability barrier, disrupts epithelial layers (widening and separating the stratum corneum), and promotes mucosal penetration and absorption across oral tissues. Because the claim specifically refers to rat studies, the verdict is supported, though certainty is rated very low due to reliance on preclinical animal models.
Charcoal in toothpaste has no intrinsic whitening effect and functions only through adsorption of tannins from the tooth pellicle.
"First of all, charcoal does not have a whitening effect. It is good at perhaps and not as good as another ingredient which we can talk about later at adsorption, not absorption, but adsorption of pulling uh tannins off a tooth off the pellicle." (said at 0:41:47)
Charcoal in toothpastes does not possess intrinsic chemical bleaching or whitening properties (unlike peroxide-based bleaching agents). Systematic reviews indicate that charcoal-based dentifrices produce no true chemical whitening effect and primarily interact with the tooth surface via mechanical abrasiveness and the physical adsorption of extrinsic chromogens (such as tannins from food and beverages) from the enamel pellicle.
Essential oils in toothpastes act as bactericides and disrupt the oral microbiome.
"And no essential oils. Essential oils actually are bactericidal. They have an effect on the oral microbiome." (said at 0:46:00)
The claim that essential oils are bactericidal and affect the oral microbiome is supported by published literature. Reviews evaluating plant-derived essential oils demonstrate that they possess direct bactericidal and bacteriostatic properties against key oral bacteria, including pathogenic species involved in dental plaque and gingivitis, thereby modulating oral microbial populations when incorporated into oral hygiene products.
- supports: Revisiting the Therapeutic Effects of Essential Oils on the Oral Microbiome. (Pharmacy (Basel, Switzerland) 2023) · cited 37x in the literature
"Essential oils (EOs) are phytopharmaceuticals, or plant-derived compounds, that possess beneficial properties such as anti-inflammatory, antibacterial, antimicrobial, antiviral, bacteriostatic, and bactericidal effects." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Antibacterial potential of essential oils against oral pathogenic bacteria: a literature a… (Journal of applied microbiology 2025) · cited 2x in the literature
"Overall, this review highlights the high antibacterial efficacy of EOs against oral bacteria and their potential therapeutic abilities." (abstract, conclusions, passage verified)
pubmedfull study (doi)
Fluoride damages the myelin sheath of neurons and impairs mitochondrial integrity in the brain.
"It does have some direct effects on the brain. Uh, it can uh, affect the myelin sheath of a neuron in the brain. It can affect the uh, the integrity of the mitochondria in the brain. We we have this data." (said at 0:52:17)
Preclinical evidence in rodent models and in vitro neural cell lines supports the claim that fluoride exposure can cause myelin sheath damage and mitochondrial dysfunction in brain tissue. Studies in mice demonstrate that high-dose sodium fluoride exposure leads to hippocampal myelin damage—marked by decreased proteolipid protein (PLP) expression and increased myelin-associated glycoprotein (MAG)—as well as altered synaptic ultrastructure. Similarly, animal and cellular studies show that fluoride impairs mitochondrial integrity and function via mechanisms such as SIRT3 downregulation, altered mitochondrial dynamics, decreased mitochondrial DNA transcription, and elevated mitochondrial oxidative stress. However, certainty is very low because these findings derive entirely from experimental animal and cell culture models, often utilizing high concentrations, rather than direct human clinical trials or human neuroimaging studies.
- supports: Effects of fluoride on synapse morphology and myelin damage in mouse hippocampus. (Chemosphere 2018) · cited 70x in the literature
"The significant reduced mRNA expressions of proteolipid protein (PLP) in medium and high fluoride groups suggested that myelin damage occurred in hippocampus." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Sirt3-mediated mitochondrial dysfunction is involved in fluoride-induced cognitive deficit… (Food and chemical toxicology : an international journal published for the British Industrial Biological Research Association 2021) · cited 42x in the literature
"These results suggest that chronic long-term fluoride exposure evokes neural/synaptic injury and cognitive impairment through mitochondrial dysfunction and its associated oxidative stress, which is, at least partly, mediated by Sirt3 inhibition in the mouse brain." (abstract, conclusions, passage verified)
pubmedfull study (doi) - supports: Effects of fluoride exposure on mitochondrial function: Energy metabolism, dynamics, bioge… (Environmental toxicology and pharmacology 2022) · cited 33x in the literature
"The present review gives a brief account of fluoride-induced mitochondrial alterations on soft and hard tissues, including liver, reproductive organs, heart, brain, lung, kidney, bone, and tooth." (abstract, conclusions, passage verified)
pubmedfull study (doi)
Sleeping with an open mouth causes dry mouth that disrupts the oral microbiome, which requires saliva and a neutral pH.
"If you're falling asleep with your mouth open at night, that is a oral microbiome a buster. I mean, it really is hard for the oral microbiome to recover the next day. It needs a lot of saliva. It needs a neutral pH." (said at 1:01:54)
Published physiologic and dental research supports the claim that mouth breathing during sleep alters the intraoral environment by lowering pH and contributing to dry mouth, which facilitates shifts toward acid-tolerant, cariogenic bacteria. A crossover study measuring continuous intraoral pH during sleep in healthy adults found that simulated mouth breathing significantly decreased intraoral pH to an acidic average of 6.6 (compared to 7.0 during normal nasal sleep and 7.3 during the daytime), with extended drops during nocturnal hours. Furthermore, reduced salivary flow and lower salivary pH are well-documented to impair the buffering capacity needed to maintain a balanced oral microbiome, leading to elevated counts of acidogenic taxa such as Streptococcus mutans and Lactobacillus species.
- supports: Intraoral pH and temperature during sleep with and without mouth breathing. (Journal of oral rehabilitation 2016) · cited 48x in the literature
"The mean intraoral pH during daytime was 7·3 (± 0·4) and during sleep was 7·0 (± 0·5). The mean intraoral pH during sleep with mouth breathing was 6·6 (± 0·5), which was statistically significant compared with the normal sleep condition (P < 0·01)." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Salivary parameters and periodontal inflammation in obstructive sleep apnoea patients. (Scientific reports 2022) · cited 20x in the literature
"According to the salivary flow rate, subjects with hyposalivation and reduced salivation had higher concentrations of salivary electrolytes and lower salivary pH than subjects with normal salivation." (abstract, results, passage verified)
pubmedfull study (doi) - supports: Association between sleep pattern, salivary cariogenic bacteria and fungi populations, pH … (Dental and medical problems 2024) · cited 15x in the literature
"The group with inappropriate sleep patterns had significantly lower pH and buffering capacity (p < 0.001) and significantly higher colony counts of Lactobacillus and S. mutans (p < 0.001 and p = 0.012, respectively)." (abstract, results, passage verified)
pubmedfull study (doi)
Studies demonstrate that pulsating water flossers (such as Waterpik), when used correctly, are more effective than traditional dental floss at cleaning periodontal pockets.
"And the studies on Waterpiks, in some cases, do a better job. Again, this is not a continuous stream of water. This is a pulsation of water that literally, if pointed in the right direction and used correctly, is better than floss. It literally cleans out the pocket and it's safe and it's easier." (said at 1:02:31)
Multiple randomized controlled trials support the claim that pulsating oral irrigators (such as Waterpik dental water jets) are as effective as or more effective than traditional dental floss for reducing gingival inflammation, bleeding on probing, and plaque in interdental and subgingival areas. For example, a 4-week randomized controlled trial comparing a water flosser to dental floss found significantly greater reductions in bleeding on probing, gingival index scores, and plaque index scores with the water flosser. Another 4-week trial demonstrated that oral irrigation was significantly more effective than traditional flossing at reducing bleeding indices.
- supports: Comparison of irrigation to floss as an adjunct to tooth brushing: effect on bleeding, gin… (The Journal of clinical dentistry 2005) · cited 74x in the literature
"Groups 2 and 3, the irrigation groups, were statistically significantly more effective than Group 1 in reducing the bleeding index at D14 and D28, whether measured by mean reduction or percentage reduction." (abstract, results, passage verified)
pubmed - supports: Efficacy of water flossing on clinical parameters of inflammation and plaque: A 4-week ran… (International journal of dental hygiene 2023) · cited 9x in the literature
"The WF group showed a statistically significant greater reduction in whole mouth BOP (0.41) compared to MBWF (0.32) and DF (0.19). This was also true for MGI (0.37, 0.30 and 0.20, respectively) and RMNPI (0.13, 0.11 and 0.06, respectively; p < 0.05 for all comparisons)." (abstract, results, passage verified)
pubmedfull study (doi)
Periodontal disease and diabetes share a bidirectional relationship where gum disease impairs blood glucose control and fluctuating blood glucose exacerbates gum disease.
"And of course, periodontal disease is intimately connected to and fires up diabetes. And I mean, this is cycle of of, you know, do you if you have gum disease, it's going to be more difficult to control your blood sugar levels. If your blood sugar levels are all over the place and it's more difficult to keep them steady glucose levels, then obviously your gum disease is going to suffer" (said at 1:06:15)
A bidirectional relationship between periodontitis (gum disease) and diabetes is well-established in systematic reviews and international consensus guidelines. Poor glycemic control in diabetes increases the risk, severity, and progression of periodontitis due to heightened systemic inflammation and impaired immune response. Conversely, active periodontal inflammation promotes systemic inflammation and insulin resistance, worsening glycemic control; treatment of periodontitis has been shown in randomized controlled trials to lead to modest but clinically meaningful reductions in HbA1c (around 0.3% to 0.5% at 3 to 4 months).
Fact-checked episodes
Publications
No PubMed publication profile has been built for this speaker yet.