• June 8, 2011
  • Dr. Catherine-Anne Walsh

I regularly see an ad on TV for a desensitizing toothpaste in which a dentist explains that you “should not give up foods you enjoy”, instead you should just use this toothpaste (I assume, forever) and your problem will not be a problem any more.

First, let’s talk about sensitive teeth. 

What causes sensitive teeth?

1. lack of saliva or poor saliva quality 

2. acid reflux or frequent vomiting 

3. acidic food and drink between meals 

4. receding gums

5. abrasive/harsh toothbrushes and toothpaste (usually combined with some of the above factors).

How are the teeth affected by the lack of saliva, acid attack or abrasion?


Little hollow channels (dentinal tubules) in the dentine layer contain long processes (like skinny fingers) of cells (odontoblasts) which lie on the surface of the dental pulp (a complex of nerve fibers and blood vessels). These tubules also contain fine nerve processes and are largely filled with fluid. Fine nerve processes also exist along the interface of the dentine layer and the pulp.   HOW DO THEY BECOME SENSITIVE?  Now that you know the anatomy, imagine these tubules reaching out to the surface of the tooth and being completely open to the outside environment. This is what happens when enamel and dentine are eroded or abraded away from the tooth surface. Now imagine the movement of the fluid in these tubules when temperature changes (fluid shrinks when cold and expands when hot), like when you have a hot cup of coffee or a cold ice cream. The changes in pressure on the nerve fibers and cell processes are conducted to the main nerve fiber in the pulp (middle of the tooth). You almost instantly feel a sharp, short sensation, like a jab or an electrical impulse in your tooth. This is called the “hydrodynamic theory” and is widely used to explain “dentinal hypersensitivity” (or in plain English: an overreaction of the tooth to environmental stimuli, rather than bacterial disease or inflammation, such as tooth decay or nerve infections). 

At an advanced stage, tooth erosion is visible and can look like the teeth in this picture. However, often the sensitivity itself is the only symptom and sign of the erosion process before any physical defects are noticeable. 

Most people treat sensitivity with desensitizing toothpaste. What do they really do?

In short, these toothpaste act like a “numbing” agent or physically “plug” the tubules. They treat the symptom, but not the disease! It’s a bit like putting a band-aid on a blister caused by shoes a size too small. Yes, the band-aid will probably cushion the blister a bit, but that won’t make the shoe bigger! Desensitizing your teeth with toothpaste does not stop the erosion process. This process will continue if the underlying causes are still present, only now you will not be alerted when it is happening and you will only know something is wrong when you look in the mirror and see the picture above. 

Understanding the message of sensitivity

Over time, even if no desensitizing toothpaste is used, fluoride from water and regular toothpaste will coat the surface of dentine and harden it, making it more resistant to minor, occasional acid attacks. However, every time renewed, persistent acid attack occurs, the sensitivity will return. While it is very uncomfortable, sensitivity is your teeth’s WARNING SIGN. It is telling you that all is not well in your mouth and that you should modify your diet, your water intake, your special care medication, your toothbrushing habits or anything else which may be contributing to the overall acidity of your mouth. To treat a painful episode of sensitivity, you may wish to use a desensitizing toothpaste. However, use it as temporary relief, not a long-term solution. 
Instead, look at your diet, overall health and your lifestyle: 
1. do you often snack between meals and what do these snacks consist of? Opt for neutral, sugar-free snacks or snacks rich in calcium. Yoghurt, nuts, cheese and milk are ideal. 
2. do you drink enough water? Ensure your water intake is adequate for your age and sex, but also reduce your intake of caffeine so you do not lose more water. 
3. are you on medication which may dry your mouth (antidepressants, blood pressure medication)? Occasionally, your doctor may be able to change your medication and reduce this side effect with a different brand or formulation. Where this is not possible, frequent water intake, chewing sugar-free gum (short spurts of up to 5 minutes), and using fluoride or bicarbonate rinses may be a good enough way to prevent further problems. 
4. do you suffer from gastric reflux? Your GP may be able to prescribe effective medication to manage this.
5. do you exercise regularly? do you use supplements or electrolyte replacement drinks which may be acidic? You may need to use special rinses to neutralize the acid in these drinks or make sure you are well-hydrated before your training session. Drink water before, during and after exercise and in between electrolyte drinks.
6. what sort of toothbrush and toothpaste do you use? We strongly recommend a soft toothbrush and a minimally abrasive toothpaste (not a whitening toothpaste), possibly a higher fluoride content if you are at high risk due to medical problems.

“Don’t give up the foods you enjoy”,  only the ones eroding your teeth!

This is a misleading statement. Some foods you really should give up. I am not sure Coca-Cola is even considered food, anyway. With other erosive foods and drinks, take them in moderation and during your usual meal times (3-4 times per day). Small lifestyle and diet adjustments are the only way to truly prevent erosion and protect yourself from discomfort and more severe complications. 
These changes are ABSOLUTELY ESSENTIAL to your health and no toothpaste will compensate for those ‘bad’ habits. For a complete diagnosis of your condition and a customized plan for treatment and prevention, you should see your dentist. Your dentist will ensure that your discomfort is not a result of a more serious condition. So, if this cold weather is hurting your teeth, don’t just reach out for the desensitizing toothpaste. Rewind back to your day or your week and what your teeth must have endured. The solutions will be very clear.

Dr. Catherine-Anne Walsh
About The Author

Dr. Catherine-Anne Walsh

Catherine-Anne is a New Zealand-qualified dentist. She holds a Masters Degree in Public Health from Sydney University and she has a broad range of experiences from working in both the public and private sector.


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