Dr. Shnall's Dental Blog
By Dr. Jeff Shnall
Dentally speaking, we are living in good times.
People are keeping their teeth longer and if an adult tooth is lost it can often be replaced in ways not even dreamed of a few generations ago (i.e. dental implants).
However, tooth decay is still a disease that affects humans and it is likely to be with us for the foreseeable future.
In my dental practise, I have patients that have never developed a cavity while others are cavity prone.
A cure to eradicate tooth decay has not been found however as a dentist my job is not only to treat dental diseases such as a cavities but to also to help prevent dental disease, especially cavities.
In this article, I will give an overview of how cavities form and ways to prevent cavities that will help save your teeth. Before we jump in, consider a few interesting facts:
Our teeth are covered by an outer protective layer, enamel, which is the hardest substance in the human body. Yes, it is harder than bone. Yet our teeth is the only part of our body that rots.
Once we die, our teeth are indestructible. Proof of that latter point is an article you can easily search online: “French archaeology students find 560,000-year-old tooth.”
However during our lives our teeth are anything but indestructible.
Our teeth are covered with a hard outer enamel layer. Beneath that layer is a less hard layer called dentin.
Our teeth are in large part made up of the minerals calcium and phosphate.
Although enamel is the hardest biological material in our bodies, it can be dissolved by acids found in certain foods and drinks as well as acid produced by bacteria that cling to our teeth.
The decay process
Our mouths are full of bacteria. Some of these types of bacteria cause tooth decay/cavities.
The bacteria found on our teeth is also called plaque and it likes to grow in the deep grooves that some people have in their teeth, in between the teeth where a toothbrush doesn’t reach as well as along the gum line.
Some species of bacteria/plaque that grow on our teeth ingest sugar and starches from food and drink we consume and convert them into acid.
If the acid that is produced remains on your tooth long enough, the acid will start to dissolve the calcium and phosphate in the tooth and a white spot will develop, a process called de-mineralization. These white spots in teeth can be reversed.
If we can stop or minimize the acid attack on the tooth by keeping bacteria/plaque off the teeth, and re-expose the tooth to enough calcium and phosphate the white spot can harden and the enamel will return to its normal appearance. The hardening of the tooth is called re-mineralization. Later I will explain how dentists can help you re-mineralize or repair white spots forming on your teeth.
If the white spot on a tooth does not regain the calcium and phosphate and the enamel continues to be dissolved by acid produced by bacterial plaque, the white spot will progress beyond the point of no return and become a cavity.
On the diagram labelled "Stages of Caries Development" (caries is another term for cavity), the "white spot" actually has progressed to become a darker area of decay which has gone untreated to the point where the decay has infected the nerve or root canal of the tooth.
What factors make it more likely you will develop a cavity?
The bacteria in plaque not only feed on sugar; they can also feed on carbohydrates found in bread, crackers, cookies, pretzels and potato chips. Yes, even bread and potato chips can cause cavities, especially if the foods we snack on get stuck in the deep grooves of our teeth or in between our teeth.
Brushing after a sugary or starchy snack or chewing a piece of sugarless gum after such a snack can stimulate saliva and wash the sugars and starches off our teeth.
Nuts and seeds do not contain sugars and carbohydrates that fuel acid production on your teeth so choosing them as a snack over chips or candies can reduce cavities.
Fresh fruit does contain natural sugars but the sugars are bound up in fibre and are less easily accessed by bacterial plaque so are less likely to cause decay. This does not hold true for dried fruit such as raisins, which are sticky and soft and whose residue can cling long enough to our teeth after we eat them to allow the bacteria to feed on their sugar content. Eating too much dried fruit can lead to cavities.
If your mouth/saliva is acidic, you risk getting larger amounts of bacteria/plaque on your teeth hence more cavities. As well, enamel and other tooth structures (i.e. dentin) will gradually wear down due to acid erosion, if exposed to acidic foods or drinks.
What determines if your mouth is acidic or not?
If you expose your teeth to acidic food or drink many times a day or for long periods of time a day your mouth, tooth surfaces and the bacteria /plaque on your teeth will stay acidic.
The acidity of any food or drink can be measured. Iced tea and lemonade are examples of two drinks that are acidic. If you drink too much of either of these beverages, you could erode your enamel and also could develop white spots and subsequent cavities.
Acidic drinks, like lemonade and iced tea for example, make plaque/bacteria more abundant for the reason that bacteria function better if surrounded by acid, as stated earlier. This higher number of bacteria on our teeth can lead to an even greater amount of acid production on our teeth, if this more abundant bacteria is fed a sugary diet.
The chart below shows the amount of acidity of some common foods and drinks and other substances.
Any foods on the left hand side of the chart are acidic and support bacterial growth in the mouth and directly break down enamel and dentin.
As seen on the chart, our enamel will start to dissolve if exposed to liquids that are a pH of 5.5 or less. So any foods or drinks below 5.5 will promote enamel de-mineralization.
From the pH chart some points to consider:
Any citrus juices or fruits such as orange, lemonade, grapefruit juice and most soft drinks
(i.e colas, root beer, mountain dew) are acidic drinks and have a pH value in the 2 to 3 range. These drinks can dissolve enamel and promote the growth of cavity causing bacteria.
If you check the label of your favourite soft drink/soda you will see citric, carbonic or phosphoric acid or even all three. Citric acid is also known as Vitamin C. Carbonic acid results from the carbonation or adding bubbles to the soft drink. Phosphoric acid is added to some soft drinks as a preservative.
Tea and coffee have a pH of 2 to 3 and also provide an environment that supports cavity causing bacteria and tooth de-mineralization.
If the tooth has periods of time when it is not being bathed in cola or juice or the bacteria is not being fed sugary drinks or candy, the tooth surface will have a chance to re-mineralize.
The re-mineralization process occurs naturally if our saliva is able to bathe damaged enamel and dentin in calcium and phosphorous. These minerals can be deposited back into the injured enamel/dentin and the tooth can harden or re-mineralize. Fluoride can also help re-mineralize a softened, de-mineralized tooth.
Sticky candy, like gummy bears or sour keys, or long lasting candy such as lollipops also expose the teeth to a longer sugar and acid attack, which can overwhelm the ability of the tooth to repair and rebuild.
Saliva washes bacteria off our teeth, and buffers our teeth (makes them less acidic) and delivers calcium and phosphorous to help rebuild de-mineralized enamel and tooth structure.
If you do not produce enough saliva, you will get:
Dental disaster strikes in patients with dry mouth who make the unfortunate choice of sucking on candies that contain sugar to keep the mouth moist or who sip on pop, juice, coffee or tea with sugar to keep the mouth lubricated.
A patient with dry mouth already has more plaque or bacteria on their teeth. The sugar will cause decay, the pop or juice provides an acidic environment in the dry mouth and the result can be devastating.
I have seen patients with dry mouth issues develop cavities in many of their teeth, under fillings and under other kinds of dental work.
Some Good News About Cavities
The good news is that cavities are not inevitable and our goal in dentistry is to prevent cavities from developing, repairing ones that start and also allow you to eat foods you enjoy without destroying your teeth.
It's about keeping the amount of acid your teeth are exposed to at a reasonable level and also promoting re-mineralization.
So here are some tips to prevent cavities based on our discussion above:
Limit acidic drinks (soft drinks, citrus juices) to meal times and limit the amount you drink.
If you are going to have acidic foods, sweets or other cavity causing carbs, limit them to when you are eating breakfast, lunch or dinner; try not to have these cavity causing/de-mineralizing foods spread over many small meals and/or snacks throughout the day. This allows your mouth and tooth surface to recover from the acidic conditions created by the acidic foods or drinks.
Milk is a better choice than soft drinks/soda and citrus juices because it is not as acidic but you should limit milk to snack time or meal time and do not sip on it for hours at a time, as milk does contain natural sugars that promote cavities.
If you must drink juice, dilute it with water. You may not like it at first but once you get used to it, you won’t even notice the difference in taste. At least that has been my personal experience. I dilute my orange juice: one part orange to three or more parts water. This is less acidic, less sweet and has fewer calories. It is an acquired taste but if I can get used to it you likely can too.
Avoid soft drinks/soda. Again for the reason that pop/soft drinks/soda contain acids and sugar. Diet soft drinks do not contain sugar but they do contain acid.
If you like to carry a drink with you to sip at during the day, tap water is best. It is fluoridated and neutral i.e not acidic.
Whereas, believe it or not, some brands of bottled water are actually acidic. There are some brands of bottled water that have a pH in the range of 3.5 to 5.0; remember that enamel de-mineralizes at a pH of 5.6
If you are a bottled water fan, search the name of the bottled water you normally like to drink online and check the acidity/pH of that brand. You may be surprised to see the amount of acidity of certain brands of bottled water.
Limit sweets and avoid the sticky ones (i.e. caramels, toffees, fruit roll ups) and definitely no lollipops (unless they are sugar-free)
Choose healthy snacks like nuts, seeds, fruits, cheese
In my next article, I will discuss products that dentists use in the office to re-mineralize white spots starting in teeth as well as dental products you can use at home to help prevent cavities.
If you have any questions or comments on this post, please free to leave a message below.
Until next time….
Dr. Jeff Shnall