Sports health: tooth truths for swimmers

While exercise and sport are good for health in so many ways, there are some potential health risks and downsides. The most obvious of these is injury, which can occur either as a result of over or incorrect training, or sports impacts and accidents – for example, collisions on the playing fields or tumbling off the bike because of slippery road conditions. Another potential risk concerns overtraining, which can lead to reduced immunity, chronic fatigue and even depression⁽¹⁾. Associated with overtraining, especially in younger female athletes, is the risk of developing an eating disorder (see this article). However, there’s a much lesser aspect of health and well being that can be negatively impacted by sports training and that’s dental health.

Dental erosion matters

How could training for sport negatively impact your dental health? One reason – especially in the case of endurance athletes – is an increased consumption of carbohydrate in the form of sports drinks to fuel longer workouts. Needless to say, these drinks invariably contain sugars (usually glucose or glucose/fructose mixtures), which provide a source of easily absorbed and digested carbohydrate. Unsurprisingly, consuming sugary drinks on a regular basis, especially when sipped over a period of time, is a great way to promote dental caries – in exactly the same way as happens in kids who eat too many sweets!

However, there’s another risk to dental health that if anything is more insidious than mere tooth decay, and that is something known as ‘dental erosion’, where the hard enamel coating on the teeth becomes gradually eroded. In a previous SP article, we looked at the topic of dental erosion in the context of consuming drinks that are acidic. These include fruit juices, lemonade, cordials and many sports drinks, which can result in an acidic environment around the teeth. This in turn can lead to demineralization and damage to the protective layer of enamel. Although this effect is not site specific (as is the case with caries), the frequent and repeated consumption of acidic drinks can, over time, erode and damage the enamel surface of the all the teeth in the mouth, greatly increasing the risk to dental health in future years.

Understanding dental erosion

Dental enamel is the hardest and most highly mineralized substance in the human body. The job of enamel is to protect the underlying dental tissue (dentine) during daily use – ie when chewing, biting, crunching, and grinding. Enamel also insulates the teeth from potentially painful temperatures and chemicals. Although tooth enamel is a completely biologically inert substance (ie having no blood supply), it is not a static tissue because it can undergo chemical changes that can cause demineralization and re-mineralization. In simple terms, exposing tooth enamel to acid (eg from acidic drinks) causes the gradual breakdown of the uppermost layer of enamel into soluble calcium, phosphate and water (demineralization).

Enamel erosion is insidious in that the early signs and symptoms may not set alarm bells ringing. These signs and symptoms include:

·        Tooth sensitivity – either to hot or cold temperatures, or to certain foods such as sweet foods.

·        Tooth rounding – the teeth can begin to take on a rounded and smooth appearance.

·        Tooth discoloration – as the layer of protective enamel become progressive thinner, the teeth may appear yellow because more dentine is exposed.

In the later (more severe) stages of enamel erosion, sensitivity may be severe enough to cause a lot of pain. In addition, noticeable indentations may appear on the enamel surface of the teeth (known as ‘cupping’). Then of course, because the enamel surface becomes thin, small cavities are much more likely to breach the protective enamel layer, leading to tooth decay and infection (abscesses).

What makes an erosive drink?

Research has found that once the acidity of a drink exceeds a pH of around 5.5, dental erosion can occur⁽²⁾. [Note that ‘pH’ is a measure of acidity/alkalinity; a neutral pH (that of water) is 7.0, with numbers below 7.0 indicating acidity and above 7.0 indicating alkalinity]. The same research found that the acidity of sports drinks can reach as much as pH 3.16 – ie 10,000 times more acidic than plain water! Fizzy drinks such as cola drinks (sweetened or unsweetened) are also culpable; the dissolved carbon dioxide lowers pH (ie increases acidity), which along with the flavourings (often acidic in themselves), further boosts dental erosion potential⁽³⁾.

Not just drinks

While acidic drinks can be harmful for enamel health, that’s not the end of the story. That’s because there’s a link between exercise, saliva and dental erosion; exercise is known to have an adverse effect on the flow rate and composition of saliva, and physically active individuals show reduced stimulated salivary flow rates⁽⁴⁾. Why does that matter? Well, saliva is the critical protective factor in the process of development of erosive lesions. Salivary flow encourages tooth remineralization, provides a buffering effect to resist pH changes in the mouth, and provides a replenishing supply of minerals to the demineralized tooth surface⁽⁵⁾. Unsurprisingly therefore, those who exercise a lot have lower levels of salivation and are more likely to have a high prevalence of erosive wear lesions on the enamel⁽⁴⁾.

The vulnerability of swimmers

Is if the above weren’t bad enough, it turns out that swimmers face another hurdle in maintaining their dental health, and it’s linked to chlorinated pool water. The recommendation is that to ensure an adequate antimicrobial effect while minimizing negative impacts to swimmers, swimming pool water should maintain chlorine level between 1.0 and 3.0 parts per million, and the pH range should be maintained between 7.2 and 8.0 – ie neutral to slightly alkaline⁽⁶⁾.

For serious or elite swimmers undergoing high training loads and spending multiple hours per week in swimming pools, this presents a potential problem. That’s because improperly chlorinated swimming pools are often found to have low pH levels (ie acidic), with reports of pH values as low as 3.0 (due to the insufficient dosing of chemicals that can soak up excess pool acidity)⁽⁷⁾. In such an environment, the constant exposure to erosive assaults by the acidic pool water means that swimmers’ teeth may become particularly susceptible to enamel erosion.