Cleaning and polishing teeth
By R. David Whitby, Contributing Editor | TLT Worldwide January 2025
While tooth enamel is the hardest biological material, an abrasive material must be significantly softer on the Mohs scale to be an appropriate dental polish.
I am indebted to TLT reader Ken Budinski for bringing to my attention a possible issue with dentists using some methods to clean and polish teeth. Ken mentioned specifically slurry cleaning.
Dental surgeries use dental polishing, also called tooth polishing, to keep a patient’s teeth healthy. At a regular appointment, a hygienist will first remove any buildup of plaque, a process called scaling, and will then use a rotary toothbrush to clean your teeth. Then a dentist will inspect your teeth for any cavities and other problems, and maybe take scans of them. The dentist may then polish your teeth to remove stains and any lasting plaque, smooth the surface of your teeth, make your teeth look shiny and help to prevent gum disease by removing bacteria from the surfaces of your teeth.
People always have bacteria in their mouths. Some types cause cavities in teeth and tooth decay. As the bacteria grow, they create a sticky substance called a biofilm, which protects them and helps them to keep growing. This biofilm helps to form plaque. Gum disease, called periodontitis, can happen when bacteria, food or plaque get beneath the gums and are not properly treated. This can lead to gum, tooth and bone loss.
Several methods can be used to clean and polish teeth. A rotary drill can be fitted with a brush or rubber cup and used at a slow speed. The brush is dipped in some dental polishing paste and then applied to the teeth. The paste is an abrasive that scrubs away any stains and plaque.
Air powder polishing uses a slurry of water and baking soda (sodium bicarbonate) with air and water pressure. This is sometimes used with an ultrasonic plaque remover. This method is used in between teeth and cracks where the brush is unable to reach and to remove plaque above the gum line. Other types of powders, including calcium carbonate, calcium sodium phosphosilicate, aluminium trihydroxide, emery, silica or perlite might be used. Air polishing can be helpful for sensitive teeth and also helps with people who wear braces, because it won’t affect them.
Coronal or cosmetic polishing removes plaque and superficial dental stains. Superfine abrasive agents are used to make the enamel (the outer layer covering the crown of the tooth) lustrous. The enamel surface is sometimes polished to an extent that it can even reflect visible light.
Superficial polishing polishes the crown of the tooth. However, this technique has nominal curative benefits and is primarily done to improve the aesthetic appearance of the teeth.
The dental slurry method of cleaning teeth is a variant of the air powder method, in that it uses only a water-based suspension of particulate material. Ideally the particulate material should have a hardness which is softer than the softest exposed part of the teeth. The slurry is directed against the teeth under sufficient water pressure for the particulate material to penetrate and dislodge any plaque or food particles that may adhere to the teeth.
Tooth enamel is mostly hydroxyapatite, which is a mineral form of calcium phosphate. The apatite group of minerals scores 5 on the Mohs hardness scale, which makes tooth enamel the hardest biological material. It is harder than steel, most types of which score between 4 and 4.5 on the Mohs scale, but is a lot more brittle. This is why people can’t scratch their teeth when eating with a metallic knife, fork or spoon. However, glass scores 5.5 of the Mohs scale and porcelain scores 7, so you can chip a tooth by trying to open a beer bottle with your teeth.
One of the dentists to whom Ken Budinski spoke claimed: “Tooth enamel is the hardest element, harder than diamond.” Unfortunately, diamond scores 10 on the Mohs scale. The Mohs scale is logarithmic. On an absolute scale of hardness, apatite minerals score 48, quartz scores 100 and diamond scores 1,500.
There appears to be a danger that selection of the wrong abrasive material for either air powder or slurry polishing may result in excessive wear of tooth enamel. The abrasive material needs to be significantly softer than 5 on the Mohs scale.
David Whitby is chief executive of Pathmaster Marketing Ltd. In Surrey, England. You can reach him at pathmaster.marketing@yahoo.co.uk.