As I said in the post about the cause of dental caries, decay results from an imbalance between healthy and unhealthy (decay-causing) bacteria.
Put another way:
Supporting healthy bacteria --> decrease in caries risk
Supporting unhealthy bacteria --> increase in caries risk
So what can we do to support the healthy bacteria, and what should we limit in order to discourage growth of the decay-causing bacteria? In this post, we will focus on the factors that lead to a cariogenic oral environment in order to learn what we can limit to decrease our risk for decay. (Spoiler: you will see where sugar and snacking factor in). We will cover protective factors in a separate post.
Lack of saliva / Dry mouth / Xerostomia
Saliva may be considered one of the most important protective mechanisms we have against dental caries. It has many beneficial components, including:
- Enzymes – initial digestion of food
- Antimicrobial components – protection against bacteria, viruses, and fungi
- Bicarbonate – natural buffering agent to restore our mouths to a healthy pH
- Proteins – many functions, including lubrication, binding minerals to allow supersaturation for tooth remineralization, and buffering capacity
- Calcium and Phosphate – minerals to aid in tooth remineralization
A lack of quality saliva, therefore, can significantly increase one’s risk for tooth decay. Dry mouth can result from aging, disease, head/neck radiation, or tobacco or methamphetamine use. It also often occurs as a side effect of common medications, including medications for high blood pressure, acid reflux, pain, depression, anxiety, seizures, and allergies. If you experience dry mouth, you should discuss with your dentist ways to counteract your increased risk for caries as a result of your dry mouth. These may include saliva substitutes, products to neutralize pH, increased fluoride exposure, or xylitol products.
Every time we eat or drink, the pH in our mouth drops. As discussed above, saliva is our natural buffering defense and restores the pH to healthy levels. In health, saliva allows the oral pH to recover to above 5.5 within 15-30 minutes, and thus allowing teeth to remineralize. However, the more often we eat or drink, the more often our oral pH drops, the more likely our biofilm will change from one of healthy bacteria to one of cariogenic bacteria, not to mention it simply results in more times that our teeth experience demineralization. This diagram may convey my point better than my words:
It may also be helpful to consider the duration of your meal, snack, or drink. Strictly thinking from a dietary standpoint, it would be better to drink only 1 soda or juice in a day, and maybe sip on it throughout the day to make it last. From a dental standpoint, however, this would be creating a day-long cariogenic environment! At this point, does that not just make you cringe? From a dental standpoint, it would be better to have 3x the soda or juice and drink it all at once, rather than a single drink sipped throughout the day. (Note: I am NOT encouraging anyone to drink more soda or juice. For the record, I advocate for less of both, but am simply trying to make my point).
Bottom line? If you eat or drink beverages other than water more than 4-5 times per day, you may be profoundly increasing your risk for decay. Of course, there are patients who cannot change their dietary regimen due to health reasons. If this is you, talk to your dentist about products to elevate the pH in your mouth after eating or drinking. Also, stay tuned for the next post on protective factors.
This is where sugar comes in to play! You now know from the previous post that bacteria that cause caries digest fermentable carbohydrates (sugars are examples of fermentable carbohydrates) and produce acid as a result. It makes sense, then, that by consuming more sugar and other fermentable carbohydrates, you are also feeding the cavity-causing bacteria the sugar they need to produce acid. A healthy diet will contain less sugar and more food that does not cause the pH to drop as precipitously, such as dairy, nuts, and fresh fruits and vegetables.
Oral appliances encompass any foreign dental object (fixed or removable) worn in the mouth for an extended period of time. These include:
- Partial dentures
- Orthodontic appliances, including braces, Invisalign, retainers, expanders, and others
- Sports mouth guards
- Occlusal splints (night guards)
- Sleep apnea appliances
- Whitening trays
These are all important and good for their own reasons, however it is simply important to acknowledge the increased risk of decay associated for 2 reasons:
- Creating hard-to-clean niches around the appliance, trapping bacteria and food debris against the teeth
- Creating zones of limited salivary exposure (I don’t need to go into this further; you have the point by now about why saliva is important)
The longer biofilm has without being disrupted with brushing, flossing, and other means of debridement, the more mature it becomes. The problem is not simply a mass of bacteria on your teeth, but the thicker and more mature a biofilm becomes, the more resistant it becomes to alteration by saliva. This means that although the pH of your mouth in general may be within a healthy range, the buffering capacity of saliva may be unable to create a favorable pH within the thick biofilm itself. This means that your teeth may still be experiencing demineralization under a thick, acidic biofilm despite an otherwise healthy pH in the mouth overall. A thick biofilm is also more resistant to other forms of disruption, like mouthrinses.
Brushing and flossing is the tried and proven way to disrupt the biofilm and force the bacteria to start at the beginning. So yes, I am one more person recommending that you brush your teeth twice a day and floss (and/or use alternative devices to clean between your teeth) daily.
Here’s a summary:
Factors that lead to an increased caries risk include:
- Lack of saliva / dry mouth / xerostomia
- Saliva has multiple components that function to protect our teeth from developing decay. A lack of quality saliva, therefore, significantly increases one's risk for decay.
- Frequent snacking selects for cariogenic (cavity-causing) bacteria
- Oral pH drops every time we eat or drink. The more frequently we eat, the more time our teeth spend in an acidic environment.
- As you know, the acidic environment favors bacteria that cause decay, as well as causes minerals to dissolve out of teeth (the start of a cavity)
- Poor diet
- Cavity-causing bacteria digest fermentable carbohydrates (ie sugars) and produce acid as a result. You already know the significance of this!
- Oral appliances
- Inadequate oral hygiene