Disclosure: We value transparency at Today’s RDH. This article is sponsored content from OraCare as part of our sponsored partner program.
A number of things are known about the effect of chlorine dioxide on wound healing and the mechanism of how that does happen. This article will explore those concepts.
As has been mentioned in other papers, we know from the studies of Yeagaki, Tonzetich, and others that volatile sulfur compounds impede wound healing. We also know from the University Studies done at Iowa that OraCare was the only rinse to remove a statistically significant amount of VSCs. As a matter of fact, OraCare removed 100% of those toxins in every test compared to chlorhexidine and 8 other popular rinses, including those rinses who claim they contain chlorine dioxide.
We also know from that same study that OraCare killed all pathogens tested compared to chlorhexidine, including red zone periodontal pathogens, Step mutans and Candida albicans. This paper will expand on these VSC findings. What is less well known are the effects of the rinse on combating pro-inflammatory cytokine reactions which contribute to collagen loss and other deleterious effects on the periodontal tissues.
One way chlorine dioxide can improve cytokine immune response is to kill those pathogens which initiate pro-inflammatory cytokines. In a study entitled “Epithelial cell pro-inflammatory cytokine response differs across dental plaque bacterial species”, done by Panagiota G. Stathopoulou, Manjunatha R. Benakanakere, Johnah C. Galicia, and Denis F. Kinane, it was found that human gingival epithelial cells “challenged with live P. gingivalis produced high levels of IL-1β while challenge with live A. actinomycetemcomitans gave high levels of IL-8. The opportunistic pathogen F. nucleatum induces the highest levels of pro-inflammatory cytokines, while the commensal S. gordonii is least stimulatory.”
This study by Panagiota, Stathopoulou, Manjunatha, Benakanakere, Galicia, and Kinane did not distinguish what initiated the cytokine response. In other words, did the endotoxins, LPS or the VSCs these anaerobes produce cause the cytokine response? We know from other studies that all of these factors can produce the cytokine response. Certainly killing those pathogens that cause this pro-inflammatory response would lessen that response because endotoxins, LPS and VSCs would all be reduced if the bacteria are eliminated.
In a study by H. Lancero, J. Niu, and P.W. Johnson entitled, “Exposure of Periodontal Ligament Cells to Methyl Mercaptan Reduces Intracellular pH and Inhibits Cell Migration” the results of this study, Journal of Periodontology, May 1999, “support the hypothesis that gases such as methyl mercaptan may play a role in both surgical wound healing and periodontal disease by adversely affecting cell function and suggest that alterations in intracellular pH may be part of the mechanism of these changes.”
They go on to say, “Although many bacteria produce H2S, the production of CH3SH, especially at high levels, is primarily restricted to periodontal pathogens. Direct exposure to either of these metabolites adversely affects protein synthesis by human gingival fibroblasts in culture. However, methyl mercaptan has the greatest effect.
Other in vitro experiments have demonstrated that cells exposed to methyl mercaptan synthesize less collagen, degrade more collagen, and accumulate collagen precursors which are poorly cross-linked and susceptible to proteolysis. CH3SH also increases permeability of intact mucosa and stimulates production of cytokines which have been associated with periodontal disease. VSC, and in particular methyl mercaptan, are therefore capable of inducing deleterious changes in both the extracellular matrix and the local immune response of periodontal tissues to plaque antigens.
This study then shows that VSCs are associated with pro-inflammatory cytokine responses that have effects against collagen in the stoma and produce membrane permeability. Removing those VSCs would most likely also reduce pro-inflammatory cytokines that are destructive in periodontal disease.
Here is the chemical reaction of chlorine dioxide with Methyl Mercaptan CH3SH + CLO2 = CH3SO2OH Methyl sulfonic acid In a related study in the Journal of Endodontics, 2004 Feb;30(2):88-91,entitled, “Pro-inflammatory cytokine profiles in pulp fibroblasts stimulated with lipopolysaccharide and methyl mercaptan,” by Coli J., Tam E., and Waterfield JD, the abstract had these conclusions and they are quoted:
“Pulpal disease is intimately associated with the immune system’s response to bacteria products. Clinical pathology is mediated in part by the production of pyrogenic cytokines, especially interleukin (IL)-1, tumor necrosis factor (TNF)-alpha, and IL-6. Methyl mercaptan (CH3SH), a volatile sulfur compound produced by anaerobic Gram-negative bacteria, has been shown to contribute to the production of IL-1 by human mononuclear cells. In this report, we investigated the production of IL-1, TNF-alpha, and IL-6 by human pulp fibroblasts when stimulated for various periods of time with lipopolysaccharide (LPS) with or without the presence of CH3SH. We found that LPS and CH3SH had no effect on the production of IL-1 or TNF-alpha.
However, LPS stimulated IL-6 production, and this production was augmented when CH3SH was present. We conclude that the volatile sulfur compound CH3SH plays a role in activation and modulation of the immune response through its role in production of IL-6.”
The conclusion that methyl mercaptan plays a role in the production of IL-6 is important. Even though this is an endodontic study, we know that IL-6 is highly destructive of collagen in the gingiva. It is the cytokine tested for in Oral DNA lab tests to gauge gingival health for patients. We know OraCare removes methyl mercaptan very effectively.
We can support that gingival connection with this study in the Archives or Oral Biology, 1995 April 40(4):337-44, entitled, “Stimulation of enzyme and cytokine production by methyl mercaptan in human gingival fibroblast and monocyte cell cultures”, Ratkay LG, Waterfield JD and Tonzetech J.
Here is the quote of results from that abstract:
“The volatile sulphur compound methyl mercaptan (CH3SH) is a by-product of protein metabolism and a principal component of oral malodour. This investigation examines the effect of CH3SH on the enzymatic activities of cathepsins B and G and elastase, and on the production by human gingival fibroblasts of two key factors, prostaglandin E (PGE) and cAMP, of the PGE2-cAMP-dependent pathway, which may contribute to the increased production of collagenase and tissue destruction in human periodontal disease. The results demonstrate that CH3SH alone, or in combination with interleukin-1 (IL-1) or lipopolysaccharide, can significantly enhance the secretion of PGE2, cAMP and procollagenase by human gingival fibroblasts. CH3SH also stimulated mononuclear cells to produce IL-1, which can increase cAMP production, and act in synergism with the direct effect of CH3SH on cAMP. CH3SH also significantly enhanced the activity of cathepsin B, moderately suppressed that of cathepsin G, but did not significantly affectelastase. These results provide evidence that CH3SH could be a contributing factor in the enzymatic and immunological cascade of events leading to tissue degradation in periodontal diseases.”
Even though this study by Tonzetich and others is earlier than the endodontic study, and some conclusions are different in minor ways, the fact that they conclude a big role for methyl mercaptan in periodontitis immunological cascades and bring in the important effects on cyclic AMP and prostaglandin E2 and cathepsin B are further evidence of the important effect of VSCs on cytokine immune responses.
Further support of these findings is found in the Journal of Breath Research, vol. 6, no. 1, February 2012, entitled, “The role of p53 in an apoptotic process caused by an oral malodorous compound in periodontal tissues: a review” by Izumi Aoyama, Ken Yaegaki1, Bogdan Calenic, Hisataka Ii, Nikolay Ishkitiev and Toshio Imai.
This study emphasizes the role of hydrogen sulfide rather than methyl mercaptan in oral disease. Their abstract conclusion is quoted here:
“Oral malodor is caused by volatile sulfur compounds (VSCs) composed mainly of hydrogen sulfide (H2S) and methyl mercaptan. In particular, H2S is an important compound, since it is a major component of physiologic halitosis. The toxicity of VSCs is similar to that of hydrogen cyanide, and is well investigated. The role of VSCs in reducing collagen in human gingival fibroblasts is one of the main sources of their toxicity to human oral tissues. It has been reported recently that H2S may cause apoptosis in several periodontal tissues. In human gingival fibroblasts, H2S inhibits not only cytochrome c oxidase activity but also superoxide dismutase activity.
The levels of reactive oxygen species are markedly increased, which causes the release of cytochrome c into the cytoplasm, resulting in caspase-9 activation; finally, the executor caspase, caspase-3, is activated. This pathway is commonly observed in cells from all periodontal tissues. Moreover, p53, an apoptotic factor, and phosphorlylated p53, which is the activated form, are increased by H2S in keratinocyte stem cells and osteoblasts. H2S also increases the expression of Bax, a primary response gene playing an important role in p53-mediated apoptosis, but maintains a lower expression of Bcl-2, an anti-apoptotic factor, in osteoblasts. It is concluded that the Bax apoptotic pathway and the mitochondrial pathway are activated by H2S.”
In this study, one can see that hydrogen sulfide, the other major volatile sulfur compound, is mentioned for its ability to accelerate cell death partly through the increase of apoptotic p 53 proteins, and the promotion of an increase in reactive oxygen species through the decrease of SOD. Osteoblasts are suppressed by HS and this may be another way bone loss is initiated along with collagen loss. Even though chlorine dioxide is a free radical itself, this study also suggests that chlorine dioxide would stop the decrease in SOD and thus promote anti-oxidant glutathione levels and therefore the health in the tissues it affects by removing the hydrogen sulfide that causes reduction in SOD. The free radical effect of chlorine dioxide is brief but the removal of HS is prolonged and likely would have a prolonged effect on the increase of SOD.
Hydrogen sulfide’s effects on osteoblasts and osteoclasts is also mentioned in this article from the Archives of Oral Biology, 2009: 54/8/723-729, entitled, “A single application of hydrogen sulphide induces a transient osteoclast differentiation with RANKL expression in the rat model”, Koichiro Irie Daisuke Ekuni Tatsuo Yamamoto Manabu Morita Ken Yaegaki Hisataka Ii Toshio Imai.
“Oral malodor is mainly attributed to volatile sulphur compounds (VSCs) such as hydrogen sulphide (H2S), methyl mercaptan and dimethyl sulphide. VSC accelerate periodontal soft tissue destruction. However, there is little information about the potential role of H2S in alveolar bone loss. The purpose of this animal study was to examine the effects of sodium hydrogen sulphide (NaHS), H2S donor drug, on osteoclast differentiation in rat periodontal tissue. Twenty-four male Wistar rats (8 weeks old) were divided into four groups: a control group and three experimental groups, which were examined at 3h, 1 day, and 3 days after topical application
of 3μl NaHS (lM in physiological saline) into the gingival sulcus of rat first molar. Expression of tumour necrosis factor (TNF)-α, RANKL, NF-κB and tartrate-resistant acid phosphatase (TRAP) was evaluated in the periodontal tissue. Three hours after NaHS application, TNF-α expression increased in the periodontal ligament. The numbers of RANKL-positive osteoblasts and TRAP-positive osteoclasts significantly increased progressively with time and reached a maximum level after 1 day. Significant up-regulation of RANKL and NF-κB mRNA was observed at 3h after NaHS application. H2S application caused a transient increase of osteoclast differentiation with up-regulation of RANKL expression in osteoblasts. H2S, which is primarily responsible for halitosis, may also contribute to alveolar bone resorption through RANKL expression.”
Therefore we see again that a study supports the hypothesis that hydrogen sulfide and disulfides stimulate alveolar bone loss. The removal of those VSCs would support the retention of bone in periodontal tissues. Immune response is modulated to normal function.
Other major contributors to oral volatile organics (VOCs) other than volatile sulfur compounds (VSCs) are the polyamines like putrescine and cadaverine, as well as indole and skatole. These toxins were discussed in the review article by Ribeirao Preto of the Brazilian Dental Journal, 2007, vol.18 no.4, Jose’ F. Siqueira Jr; Isabela N. Rocas, Department of Endodontics, Estacio de Sa’, University, Rio de Janeira, RJ, Brazil entitled “Bacterial pathogenesis and mediators in apical periodontitis.” Again, this is an important endodontic study and addresses a much-ignored subject of bacterial toxins in root canals which is not well addressed by the present irrigants including bleach.
Here are the most important quotes from that review:
“Several end-products of bacterial metabolism are released to the extracellular environment and may be toxic to host cells, cause degradation of constituents of the extracellular matrix of the connective tissue, and interfere with the host defense processes. Among diverse bacterial end-products, volatile sulfur compounds, short-chain fatty acids, polyamines, indole and ammonia have been regarded as putative virulence factors.”
“Volatile sulfur compounds are formed as a result of desulfuration of amino acids containing sulfhydryl groups. For instance, hydrogen sulfide is derived from desulfuration of cysteine and methyl mercaptan from desulfuration of methionine. It has been demonstrated that in numerous oral bacterial species, including candidate endodontic pathogens, are able to form volatile sulfur compounds.
Examples include: Treponema denticola, Tannerella forsythia, Porphyromonas endodontalis, Porphyromonas gingivalis, Prevotella intermedia, Prevotella nigrescens, Fusobacterium nucleatum,Parvimonas micra,Actinomyces species, and Eubacterium species. Volatile sulfur compounds are expected to be formed by endodontic bacteria from the free sulfur amino acids present in tissue fluids or exudate that penetrate in the root canal.
Proteolytic activity of some bacterial species in the root canal can also supply other bacteria with suitable substrates for production of volatile sulfur compounds. These substances can be highly toxic to host cells. Although no study seems to exist as to the production of volatile sulfur compounds in infected root canals, it is entirely possible that these compounds may accumulate in necrotic root canals and reach toxic levels to the periradicular tissues.”
“Polyamines are produced by microorganisms as a result of amino acid decarboxylation by decarboxylases. Examples of polyamines include putrescine, spermidine, spermine and cadaverine. These enzymes are present in several bacteria, including species of the genera Enterococcus, Pseudomonas, Lactobacillus, Escherichia, and Staphylococcus. Polyamines may be involved in the maintenance of cell viability, stimulation of cell proliferation, and modulation of inflammatory processes. Polyamines can dysregulate apoptosis of polymorphonuclear leukocytes and lead to premature cell death.
A study has identified and quantified polyamines in infected root canals and demonstrated that greater amounts were detected in teeth with spontaneous pain, swelling and foul odor when compared to asymptomatic teeth (88). The authors suggested that intracanal polyamines, especially putrescine, might leak out through the apical foramen and be involved in the development of pain.”
From this article one can see that the poly amines among other bacterial toxins are poorly researched contributors to pain and tissue destruction. We do know that chlorine dioxide neutralizes not only VSCs but also the polyamines.
The conclusion of this review article is that chlorine dioxide has the potential to positively affect the immune response if many ways. The removal of VSCs and VOCs would have the potential to reduce IL-6, slow osteoclastic activity, reduce membrane permeability, reduce collagen loss and improve collagen synthesis, reduce pain, promote cellular anti-oxidant levels, normalize cellular pH, down regulate inflammatory immune response cascades, improve epithelial migration and basal cell membrane formation in wound healing, reduce premature cell apoptosis, and reduce the production of cAMP, cathepsin B, IL-8 and IL-1b. The reduction in pathogenic bacteria would not only reduce the production of VOCs but also reduce LPS and other major endotoxins so destructive to oral tissues both gingival and endodontic. Right now there is only one rinse on the market that both kills these bacteria but also removes the toxins and that rinse is OraCare.