Diet and tooth decay - the science and how to apply it to your own life.

WHAT DECAYS MY TEETH?

The definition of something that can decay teeth is something that can be described as a fermentable carbohydrate. That is, something that can be brewed into alcohol. Wheat is made into beer, grapes into wine and apples into cider. If we want to brew at home we add bags of granulated sugar to increase the fermentable carbohydrate content. This makes more food available to the yeasts that create the fermentation. Caries venn diagram

Take a tooth, add bacteria and fermentable carbohydrate and you have potential for decay.

Tooth decay has been around for millennia and yet we still seem to have failed as a society to control it well.  A little science may explain some of the ins and outs and give a way to live life without having decayed teeth.

CARBOHYDRATES

Carbohydrates vary in size, from large  molecules which are slow to break down to small ones that are easily used as food. The granulated white sugar we use is made of sucrose, which is simply glucose (the sugar our brains use) and fructose (natural fruit sugar) joined together.Sucrose chemical diagram

Microorganisms find it easy to use - they simply split it into the two halves and use it as food. We're used to this process in brewing. The yeasts make alcohol and carbon dioxide as waste when they feed, which we use to our advantage to brew our beers and so on. But if we don't manage the process well the wine or beer turns to vinegar which is acetic acid.

 

APPLICATION

When we apply this to bacteria in the mouth the process doesn't generate alcohol as waste, it creates acid instead. It's this acid that dissolves the teeth.

When dentists polish a set of teeth to a perfectly smooth surface, within half a minute debris from the mouth settles and creates something called the 'acquired pellicle'.  This is the foothold that plaque uses to grip the tooth surface. Over the next few hours the plaque matures to create an ecosystem that is nothing short of astonishing in complexity.

Drinking something like a sugary drink causes rapid production of acid by the plaque bacteria but the plaque layer holds the acid against the tooth surface for a long time. So, a quick swig of a sugary drink may last 10 seconds but the acid produced may last half an hour. Tooth enamel starts to dissolve at pH 5.5 and will continue all the time the environment is acidic.

There's a full explanation of what the pH scale is in the section on acid erosion of teeth and sensitivity.

This graph is a representation of just that process.

Stephan Curve

It's called a Stephan Curve and shows the rapid drop in acidity after a sugary mouth rinse and then the slow climb back to a level that's safe for tooth enamel.

SO HOW DO WE APPLY THIS?


We used to think that it was possible to have five 'acid attacks' per day and suffer no ill effect. Thinking is changing and the tendency is to think more along the lines of three 'acid attacks' per day. Indeed there's evidence that even the Government's 'Five a day" is bad for your teeth! Saliva is amazing stuff that's effectively a soup of the stuff that teeth are made of and given enough time the tooth surface that's been dissolved can be reformed. But we have to give it enough time. If the attacks are too frequent there's more dissolve than repair goes on and the tooth gets damaged. The link above is to Wrigleys pages about saliva. Our founder, Mike was actually one of the students in 1979/1980 who generated their data about how chewing gum after meals helps buffer the acid attack. After chewing raw gum or wax every Wednesday morning for 30 weeks and then spitting into test tubes he's actually quite anti chewing gum!!

 

The length of an attack will vary. Sugar in Coca Cola, CokeSome attacks are caused by a quick swig of a sugary drink. That is sugary, not sweet - sweet could be a "diet drink", that's full of artificial sweetener. (To quote the BBC - "other sweet drinks are available"). A swift swig of sugary drink would give a standard length attack. Some attacks are caused by eating food that sticks to the teeth, so these can give a longer attack because they feed sugar into plaque for longer. If these are also a combination of small sugars and large carbohydrates, which break down at different rates the attack will be even longer. Cup cakeA fig roll biscuit would be a good example of something with a complex biscuit around a natural fruit sugar.

RELATIVE CARIOGENICITY OR CARIES POTENTIAL INDEX - (CPI)

This next table is great! Cariogenicity is how easily things decay teeth. If white sugar is given a value of one, then a higher number means it'll decay teeth more easily than sugar and a lower number means it'll decay teeth less easily. The names at the top are the people who did the research.

 

RANKING

MUNDORFF ET AL

 

NAVIA AND LOPEZ

 

HIGH CPI

RAISINS

1.21

RAISINS

1.7

1 +

BUNS

1.17

CREAM BISCUIT

1.25

 

BANANAS

1.11

PRETZELS

1.2

 

CHIPS

1.09

CARAMEL

1.02

 

SUCROSE

1

CHOC. WAFER

1.01

 

 

 

 

 

MEDIUM CPI

GRANOLA

0.94

SODA CRACKER

0.78

1.0 TO 0.5

BREAD

0.91

CHOCOLATE FUDGE PEANUT BAR

0.69

 

SPONGE CAKE

0.76

 

 

 

GRAHAMS

0.76

 

 

 

DOUGHNUT

0.7

 

 

 

RYE CRACKERS

0.68

 

 

 

CORN STARCH

0.67

SUGAR CHOCOLATE

0.61

 

POTATO CRISPS

0.55

 

 

 

PRETZELS

0.54

 

 

 

 

 

 

 

LOW CPI

YOGHURT

0.44

MILK CHOCOLATE

0.32

0.5

LUNCHEON MEAT

0.42

 

 

 

PEANUTS

0.42

 

 

 

CORN CHIPS

0.4

SKIMMED MILK

 

 

 

 

 

 

You can download this table as a PDF file here

What a surprise! Bananas and raisins are bad for your teeth! Really bad! And chocolate is not so bad. So, what's the moral? It's very difficult to make out what's the worst thing that's going to decay your teeth when you're standing in your local supermarket trying to read a label -  so read on!

Headline from the Dental Tribune, March 2012 - 'Five-a-day' causing tooth decay.

SALIVA

If we go back to saliva, it's amazing stuff. (We have books just about saliva!) In terms of acid attacks, saliva mops up the acid (this is called buffering) and returns the acidity to normal. It buffers best when the saliva has been stimulated by chewing, because it contains more bicarbonate, which reacts with the acid and neutralises it.

 

There's most saliva at meal times and least in the night, so we have the potential nightmare of a food that sticks to the teeth being eaten just before bed time. It naturally produces acid for a long time, isn't washed away by saliva and isn't mechanically cleared away by movement of the tongue. DON'T EAT JUST BEFORE BED!!!

 

APPLYING THIS TO REAL LIFE

 

For five years our founder, Mike was a dentist for people with special needs. He used to treat two distinct groups of patients.

·     The first were adults with severe and profound learning difficulties. They were people who lived in institutions and all their needs were provided for. All food and drink was provided for them by their carers. As is often the case with people with learning difficulties, swallowing of saliva is poor and the mouth tends to be a very wet environment.

·     The other half of the patient group were adults with mental health problems. Many of the medications given for mental health problems cause a dry mouth and if you have a dry mouth you'll naturally seek out a drink. The hospital foyer had a soft drinks machine and, as many of the patients had free access to the machine, they would drink sugary drinks on a regular basis.

They'd paralleled the most famous study ever in dentistry - the Vipeholm study. The Vipeholm study would never happen today! It was utterly unethical, but was critical in proving the link between sugar and decay.

The difference in the pattern of disease between the two groups was striking.


The patients with learning difficulties generally had very poor oral hygiene. Mainly because they suffered with what is described as "behaviour that challenges". Basically, to try brushing their teeth was dangerous - so it generally didn't happen for long periods of time. But in five years he saw rampant gum disease and almost no decay. On the other hand, the mental health patients would have dozens of cavities. Part of the problem is the lack of saliva, but the majority is the frequency of attack. People with learning difficulties who live in institutions are fed three meals a day. They don't 'graze'. It's grazing that does the damage.

SO - IN A NUTSHELL- DON'T GRAZE


  • That is, limit the number of times in a day that you consume 'fermentable carbohydrates'. Eat meals. Don't nibble between meals.

  • Don't eat or drink within an hour of bedtime.

  • Brush your teeth before you go to bed to remove as much debris as possible.

  • Don't take a drink to bed, unless it's water.


  • AND DON'T GRAZE!

"A little bit of everything does you good" - remember that? I suspect it's not far wrong! Sweets all day, fat all day, carbs all day - we all know it's stupid


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© Hesslewood Lodge Dental Practice, 16th November 2015