NDCS experts address FAQs about oral health and hygiene

Is it possible to be allergic to commercial toothpaste?

Dr Low Yi Han, Periodontist, Periodontic Unit, National Dental Centre Singapore (NDCS), a member of the SingHealth group: Yes, possibly to flavours/fragrances in the toothpaste, such as c​innamal (flavouring from cinnamon) spearmint, peppermint, carvone (oils from caraway seeds) and anethole (flavouring from star anise, fennel and anise).

How much toothpaste do you need?

Dr Low: A pea-sized amount is sufficient. Toothpaste contains a lot of abrasive chemicals that can cause unnecessary wear and sensitivity, so using too much is not good.

Is it hygienic to keep toothbrushes in the toilet?

Dr Low: It is fine to keep them in the toilet, so long as they are kept separated, clean and dry to avoid cross-contamination by bacteria.

Should we brush our teeth after waking up in the morning or after breakfast?

Dr Low: Either is fine, but if you brush your teeth after a meal, try to do it only 20 to 30 minutes later. This is because food reduces the pH level in the mouth. When the pH level drops, our oral environment becomes acidic and our teeth are more vulnerable to attack. Saliva in the mouth will gradually clear out the acid and lay down new calcium to repair patches of teeth that were dissolved during this 20- to 30-minute time frame. Thus, it is always advisable to allow the pH level to recover before you brush your teeth.

Some say rinsing your mouth a few times a day is important. Is that true?

Dr Low: Rinsing your mouth gets the food remnants out when brushing is inconvenient. if you are diligent about flossing and brushing twice a day using the right technique, you should not even need a mouthwash. However, if you have mouth sores or gum diseases such as gingivitis or periodontitis, a prescription mouthwash can help reduce bleeding and inflammation.

Can rubbing salt on teeth help prevent decay?

Dr Low: It used to be a traditional home-style alternative to using mouthwash at a time when dentistry was not advanced. But rubbing salt on teeth actually causes abrasions on the tooth surfaces.

Why do some people grind or clench their teeth when they are asleep? Is this harmful? How can it be prevented?

Dr Sapphire Gan Tsering, Senior Registrar, Prosthodontic Unit, NDCS: There is no proven cause of tooth grinding or clenching. However, they are often associated with stress, habitual tendencies or disturbed sleep cycles. Prolonged and intensive grinding or clenching of teeth can cause the teeth to break down – this can range from minor enamel chipping to vertical tooth fractures. It can also cause the masticatory (chewing) muscles to become tender and the jaw joints to wear down more quickly.

Suggested prevention strategies for tooth grinding include counselling sessions, massage therapy, and adopting regular sleeping patterns. To minimise the destructive effects of tooth grinding, wearing a night splint (dental appliance used at night) is often recommended.

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Ref: S13