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  • Tony

Hot Topics in Dentistry: MMIs- part 2

Updated: Jul 12, 2021

  1. Amalgam

  2. Sugar Tax

  3. Fluoridation


Amalgam is a commonly used mixture of metals for filling teeth. It's usually made from mercury with some other metal like nickel.


  • Mercury is the most toxic non-radioactive element to humans

  • No barrier in the body is impermeable to mercury, not even the blood brain barrier

  • Small amounts of Mercury vapour is released by amalgam fillings daily

  • One molecule of mercury can kill nerve cells

  • Mercury has environmental problems

  • Aesthetics (composite fillings look better)

  • More tooth structure needs to be removed (shift towards minimally invasive dentistry)

  • May lead to discolouration of surrounding teeth

  • Teeth may fracture with cooling of the hot liquid


  • Easier to use than composite fillings

  • Shorter appointment times

  • Fewer visits

  • Research shows it is 'safe'

  • Durable and inert

  • Relatively cheap

Sugar Tax

The tax was first introduced for soft drinks in Mexico as measure to reduce the childhood obesity epidemic.


  • In the first year, there was a 12% decrease in quantity of soft drinks purchased in Mexico.

  • The extra revenue generated by the tax can be used usefully

Fruit and veg



  • Largely supported

  • Pillars of ethics: beneficence

The government has a moral obligation to care for the population

  • Will also reduce tooth decay, diabetes and other disorders

Which will reduce pressures on healthcare systems


  • Disproportionately affects poorer people



Soft drinks can help people with diabetes

  • The number of soft drinks purchased in Mexico has risen

Calls to elevate the tax

Slippery slope of taxes increasing and soft drinking becoming out of reach for some

  • There are other causes of obesity and focusing on these (eg education) is a more effective way to reduce it.

Fluoridation Fluoride is sometimes put into water systems in order to prevent tooth decay (toothpaste also contains fluoride.) Don't be confused with chlorination. Chlorination is meant to kill bacteria. Pros:

  • Everyone drinks water so this does not favour certain subsets over others (eg poor vs rich)

  • Effective in inhibiting tooth decay

Fluoride binds to tooth enamel, reducing its solubility in acid


  • Ethics

Some people don't know there is fluoride in water

Does not respect autonomy

  • There are side effects such as dental fluorosis

This is the mottling of teeth

  • Although it is a purely aesthetic problem

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