Are your teeth sensitive after eating fruit? Are your teeth particularly sensitive after eating grapefruit?
Sensitive teeth are an enormous problem for dentists and patients alike. In our practice, it is the most common form of dental pain that our patients suffer from. In an average day, we'll see several people with sensitivity and year on year the problem is increasing. The pain varies from twinges to severe pain triggered by hot, cold and sweet foods or even sucking air over the teeth.
The first thing is not to jump to conclusions. We have to make sure that the discomfort isn't something more fundamental, something we must intervene in. Once we've excluded the things that dentists have to treat, we can get down to the basics of why teeth get sensitive......
Understanding the cause of sensitivity is fundamental to curing the pain
When we're in our teens, the root surface of our teeth is covered up by the gum around the tooth. As we age, the gum line matures quite naturally, so that our teeth look longer as we become adults than they did in our early teens. As we progress beyond our teens, the gum can recede due to a combination of poor brushing technique and gum disease. In a proportion of cases the recession is caused by the tooth trying to bend under stress from grinding and clenching of the teeth (bruxism). This process is called abfraction and because the tooth structure is very difficult to bend it fractures microscopically, opening up the tooth surface.
When your tooth grew all those years ago, the cells that grew them gradually retreated to the inside of the tooth, leaving behind tubes containing a long finger of the original cell. This tube goes all the way from the pulp (the "nerve") to the outer edge of the dentine. Inside the crown of the tooth, the dentine is hidden by enamel unless there's been severe wear. In the root, these tubes come all the way out to the outer surface. They're normally blocked up at the ends by plugs of mineral formed from the contents of saliva, but acid can dissolve these plugs away.
This picture is a very thin slice of tooth with light shining trough it. The top layer is enamel, protecting the inner tooth. The layer with lines in is the dentine. Each of the lines is one of the tubules. They grow from the line where enamel and dentiine meet (the Amelo-Dentinal Junction) right down to the pulp (nerve).
plugs are dissolved away, when we put hot, cold or sweet substances on the
surface, or suck cold air over the surface, the water in the finger of cell
inside the tube is sucked in and out, transmitting that movement deep into the
tooth. This picture is looking at the outside end of the tubules. The dentine that has been exposed and then attacked by acid. The ends of the tubules are wide open.
So the pain is caused by acid erosion of the outside of the tooth. This has dissolved the plugs in the ends of the tubules and left them open to the environment. Then hot, cold and sweet substances cause hydrostatic change in pressure in the very long finger of cell which goes right down into the "nerve".
So how do we stop the pain?
Quite simply we need to recreate those plugs in the end of the tubes. We have various ways of doing it. In the surgery, we use varnishes or resins that are designed to create an instant plug in the end of the tube. At home you can use an anti-sensitivity toothpaste - these work in various ways, from "pickling" the end of the finger in the tube to creating a mineral plug in the end of the tube. Again, it's about stopping fluid being sucked in and out of the tube.
But, we're just papering over the cracks - we're treating the symptom but not the reason for the pain.
Why did the naturally occurring plugs disappear in the first place? In a word, acid - particularly in combination with an abrasive. If the surface of the tooth has been attacked by acid, the centre of the crystals that make up enamel is dissolved, leaving just the outer shell of each one. it's temporarily very fragile. Give it time and it'll soak up new minerals from saliva and harden up again; but if the tooth is assaulted with a hard brush combined with an abrasive toothpaste soon after an acid attack, the surface is stripped back while the surface is still soft. The surface gradually disappears and will NEVER come back.
As the plugs in the ends of the tubes are superficial, if they've been exposed they disappear at the same time, leaving the raw ends of the tubes open. Result - pain! Even if we paint the surface with varnishes or resin, we'll give you temporary relief, but you'll be back, time and again as the surface gradually disappears. Unless the habit changes.
Strategy to avoid sensitivity
As a society our diet is changing. It's dividing into two distinct styles of diet, on one hand we have the explosion of junk food, but this is being counterbalanced by the people who consciously consume a diet that's perceived to be healthy.
From a dental point of view, both styles of diet have problems.
Both still and carbonated soft drinks are far more acidic than needed to dissolve the dentine surface of the
tooth, which will dissolve at pH6.
But so is fruit and natural fruit juice. Enamel dissolves at a more acidic pH5.5.
See our table of pH of drinks via this link. If you'd like to find out the acidity of something you drink, bring it into the practice and we'll test it for you with our in house pH test meter. It takes about two minutes and we'll add it to our list for the benefit of others.
So, we need to restrict the acid assaults on the tooth surface, but where is the acid? Here are some of the prime suspects:
· Fizzy drinks - including carbonated water
· Beer, cider
· Fruit squash drinks
· Fruit - even fruit that seems sweet
· Stomach acid if you're prone to acid reflux (heartburn) or vomiting
There's an irony here. We see sensitivity due to excessive drinking of fizzy drinks and squash BUT we see far more sensitivity in people who lead healthy lifestyles - the ones who eat plenty of fruit, drink carbonated mineral water or sports drinks and add the odd glass of wine. They're often the ones who'll snack on fruit, but because they're health conscious they'll often brush their teeth immediately afterwards - stripping away tooth surface.
The UK Government recommendation for five portions of fruit and vegetables a day is misleading. The problem is that fruit is often an individual package, such as an orange or apple, so we favour them. Indeed, the media tend to favour them when using images of a healthy diet, probably because they're easier or more attractive to photograph. This image was top hit on Google Images when I searched for "five a day". It's from a national newspaper and I think sums the problem up.
Let's try tipping the concept on its head to five portions of vegetables and fruit. The acid content effectively disappears if we eat mainly vegetables instead of fruit.
Let's beware of brushing our teeth immediately after eating fruit - for instance, if you're going to have fruit at breakfast, brush your teeth before, not after. You'll be fine, your teeth won't fall apart and your sensitivity caused by eating that grapefruit - or drinking fruit juice and brushing immediately afterwards will go away.
· Cut the frequency of acidic foods and drinks. Five oranges a day is NOT normal behaviour.
· When you drink acidic drinks, try using a straw. That way, the fluid avoids most of its contact with the teeth. Beware of taking large mouthfuls of drink and then having to "pouch" the fluid into your cheeks to be able to swallow it, thereby bathing the cheek sides of your teeth in acid.
· Don't swish drinks around your mouth.
· Beware of sour sweets - sour means acid. They'll just dissolve your teeth.
· Don't use an abrasive toothpaste. Most so called whitening pastes are just a more abrasive version and simply scour away stain - they DO NOT change the colour of the tooth. If you have a whitening effect, it's because some of the brown haze the teeth were hiding under has been abraded away, probably with part of your tooth surface (the bit that was stopping you being sensitive). If your teeth are staining it's because your brushing technique is wrong. Go see a dentist, get a good scale and polish done and follow the advice you're given about brushing technique - technique that's tailored to you as an individual.
· Don't use a hard brush. You'll hack yourself to pieces and the brush won't flex into the recessed parts of your teeth, so they'll stain even more while you destroy the more prominent parts of the tooth. Ironically, if you thin down the enamel covering of your tooth it'll get darker, NOT lighter because the underlying dentine is inherently darker than the overlying enamel.
· Get your heartburn looked at by your GP. If you get it regularly, it needs sorting out properly. Don't just depend on Gaviscon - get it sorted - that's an order!
© Hesslewood Lodge Dental Practice, 15th November 2015