Periodontal Myths and Mystery Series (III) – How Diet Influences the Dental-Systemic Disease Relationship

Any dental student in Germany would certainly fail his/her final exam if carelessly talking about the role of “fluor” in preventive dentistry. An assumed power of environmentalist pressure groups is very much feared among cariologists who want to make sure that it is fluoride, not fluorine, which has its most important part in the prevention and early treatment of dental caries. One possible accident of a child ingesting several fluoride tablets would suffice to provide environmentalists with further arguments. Elemental fluorine is highly toxic, in contrast to fluoride which is not so toxic, and environmentalist propagandists have used the public’s lack of knowledge to differentiate for manipulating public opinion against water fluoridation and further application and wide distribution of fluorides which have certaily resulted in most of the observed post WWII caries decline in all industrialized countries. So, dental students are advised to be precise. Fluorides are used in preventive dentistry, not highly toxic fluorine (“fluor”). As table salt is not chlorine!

The frenzy about fluorides in cariology appears to be based on the concept that dental caries is a result of fluoride deficiency. While it is undisputed that modern oral hygiene includes daily toothbrushing with fluoridated toothpaste (1450 ppm), additional application of, for instance, fluoride mouthwash may be restricted, based on current evidence, to caries-active individuals, in particular between 6 and 18 years. Most recently, 0.5% to 1% chlorhexidine gel alone or in combination with fluoride or 0.12% chlorhexidine mouthwash alone or with fluoride for prevention of coronal caries was not recommended, based on expert opinion in the former and strong experimental evidence in the latter case. Cariologists have expressed concern that antimicrobial mouthwash not containing 0.2% NaF would have deleteterious effects on intraoral fluoride retention and ultimately lead to increased caries risk. Despite the fact, that the concern is mostly based on analogy thinking and hard evidence consisting of properly conducted randomized controlled trials is largely missing, it has resulted in a clinical dilemma as regards the desired plaque-inhibiting effects of mouthwash which is usually used after toothbrushing with fluoride-containing toothpaste (1450 ppm). Plaque and gingivitis reducing effects of numerous antimicrobial mouthwashes have long been proved, see here, here and here; and for certain patients in particular with periodontal disease and suboptimal oral hygiene they may be recommended as adjuncts to toothbrushing. In response to cariologists’ concerns, some manufacturers have increased fluoride contents in the meantime (not sufficient according to some cariologists) and students are advised to carefully study declared compounds and their concentrations before advising patients.

Students are well aware of the fact that caries can be prevented by means other than fluoride. They do essentially company-driven saliva tests for mutans streptococci and lactobacilli, buffer capacity and flow, which is an important part of caries risk management at any dental school. They try to improve oral hygiene as they do diet counceling knowing that diet cannot easily be changed and oral hygiene improvement maybe elusive. So, fluorides is most promising, isn’t it?

Without any doubt, fluorides have revolutionized caries prevention in the past four decades. In 1999, the U.S. Centers of Disease Control and Prevention had listed fluoridation of drinking water (which is fortunately not accomplished in most places) among the ten greatest public health achievements. But when it comes to the questions, What causes dental caries? and, How can it be prevented in the first instance? one has now to regard fluorides as an antidot for an utterly unhealthy lifestyle which ultimately leads to dysbiosis of dental plaque: excessive consumption of refined carbohydrates. Of more concern must be, of course, further consequences thereof, i.e. obesity, diabetes, cardiovascular disease, certain types of cancer; all chronic non-communicable diseases. Systemic chronic non-communicable diseases, typical for post WWII Western civilization, are all associated with dental diseases caries and periodontitis. They are basically chronic non-communicable diseases, too, although there have been eager attempts to prove that both caries and periodontitis may in fact be transmittable. This is mainly based on certain bacterial species, in particular Streptococcus mutans and Aggregatibacter actinomycetemcomitans, which can be transmitted vertically (from parent to child) and probably also horizontally (between partners).  But that applies for the entire oral microbiome.

Apart from diet, another key player must be mentioned, smoking. The hidden epidemic of smoking in the 20th century has been made responsible for many types of cancer, cardiovascuar disease and, very lately, also periodontitis. The current hype about whether periodontitis may be causally related, at least in part, for cardiovascular disease and diabetes (the association with the latter has now factually become “bi-directional”) may indeed be spurious as there are two basic causal factors, smoking and excessive consumption of refined carbohydrates, which may link all chronic non-communicable diseases. The critical review article by Hujoel (2009) which motivated me to write this post, provides a meta-analysis of some more or less “forgotten” trials which have shown that moderate reduction of refined carbohydrates may in fact reduce gingivitis.

In Kuwait, type 2 diabetes mellitus prevalence has recently reached 23%. This rate exactly matches the rate for overweight and obesity in Kuwait, and young Kuwaitis are increasingly seen at risk for hypertension and cardiovascular disease. Prevalence (Prev) of 23% of the risk factor (RF) for periodontitis may allow calculation of an attributable risk (AR) of type 2 diabetes mellitus, which may increase the risk for periodontitis by a factor of 3 (relative risk, RR), of almost 32% [AR = Prev(RF)*(1-RR)/1+Prev(RF)*(1-RR)]. There are currently no data available as regards prevalence of periodontitis among Kuwaitis and non-Kuwaitis.

Recently, the WHO has amended their recommenadtions as regards intake of free sugar to less than 10% of total energy intake, roughly 50 grams per day. The WHO guideline does not refer to sugars in fresh fruits and vegetables, and sugars naturally present in milk, because there is no reported evidence of adverse effects of consuming these sugars. A further decrease to 5% (25 grams) would provide additional health benefits. Dr. Francesco Branca, Director of WHO’s Department of Nutrition for Health and Development, explained,

“We have solid evidence that keeping intake of free sugars to less than 10% of total energy intake reduces the risk of overweight, obesity and tooth decay. … Making policy changes to support this will be key if countries are to live up to their commitments to reduce the burden of noncommunicable diseases.”

So, understanding biological mechanisms by which systemic and oral civilization diseases are linked is revealing. But lessons learned can easily be adopted for preventing them altogether: smoking cessation and low carb.

5 May 2015 @ 7:27 am.

Last modified May 8, 2015.

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