Chewing sugar-free gum helps protect your teeth and gums in between meals when it may not be possible to brush with a toothbrush and fluoride toothpaste. Having sweeteners rather than sugars means that it does not cause tooth decay. In fact, the sweetener Xylitol helps to prevent plaque bacteria sticking to the teeth. Studies have shown that xylitol can help reduce tooth decay and even help reverse the decay itself by helping to replace the minerals in tooth enamel.
Your teeth are more at risk of acid attack after you have eaten. The acid is produced by plaque bacteria, and the sugars in our food and drink, and it slowly dissolves away the enamel and dentine of the tooth, to produce a hole or 'cavity'. (Plaque is the thin, sticky film that keeps forming on your teeth. It contains many types of bacteria which can cause tooth decay and gum disease.)
You can reduce this acid attack by chewing sugar-free gum, as it helps the mouth to produce more saliva - the mouth's natural defence against acid.
Dental erosion is caused by the acids in the things we eat and drink, such as citrus fruit, fruit juices and fizzy drinks. These start to eat into the enamel covering the teeth, and remove some of the minerals making up the enamel. By helping us make more saliva, chewing sugar-free gum can also help to reduce this type of acid attack. It takes the saliva about an hour to replace the minerals that the enamel has lost. Chewing sugar-free gum for 20 minutes after eating or drinking can increase the flow of saliva, and help replace the minerals more quickly.
See the diagram below. It shows how your tooth enamel is at risk from acid attack after food and drink, and how long it takes the acid level in the mouth to return to the safe zone. pH is the measure of acidity, with levels below 5.5 being acid enough to soften tooth enamel. Chewing sugar-free gum after eating can quickly lower the amount of acid that attacks the teeth.