Although the teeth are crowned with enamel, the hardest substance in the human body, they're really just softies at the root and on the inside. Teeth have hard surfaces in order to help break down food so the body can digest it, but their roots below the gum line are coated in cementum, which is a soft outer layer. Pulp, another soft substance, fills the insides, or cavities and canals of teeth.
Why aren't the teeth all hard and durable by design? It may be because they need nutrients, which are absorbed through soft, rather than very hard or almost impenetrable materials like enamel. Nerves, tissues and blood vessels make up the pulp underneath tooth enamel, and dentin is a covering below enamel that serves as kind of the last line of defense between the outside world and the delicate roots and nerves within the mouth. Once the enamel is cracked or eroded and the dentin is exposed, thousands of little channels, or tubules in the dentin become pathways to pain as they fill with fluids or air and receive external sensations that reach down through the nerves [sources: ADA; BBC; Colgate].
Dentin sensitivity, root sensitivity and dentin hypersensitivity are alternate names for tooth sensitivity, and no matter what you call it, by some estimates you have about a 50/50 chance of having sensitive teeth [source: Colgate]. Despite how strong tooth enamel is, once the gums begin to recede or push back from the parts of the tooth below the crown, or hard part, bacteria work fast to attack and multiply in and around teeth. Blood flow within the gums and saliva and other fluids flushing through the mouth perform beautifully at managing bacteria until something compromises the soft tissues and coverings, and the nerve doors, so to speak, are thrown wide open. Just as the skin of the human body is one of our first lines of defense against infection but becomes a major entryway once cut open and exposed to microbes, the teeth have "skins" of their own. Once uncovered or partially exposed, teeth have heightened sensitivity.
You may be a bit of a softie inside as well, but is it possible you've been more than a little hard on your teeth? Or perhaps you've been a little soft on discipline when it comes to dental care? Whether we cause our own pain is a sensitive subject, but we'll break it down gently, next.
How We Make Our Own Teeth Sensitive
Brushing after meals and flossing daily is the best way to prevent most dental problems, including sensitive teeth. Poor oral hygiene leads to plaque buildup and if not removed while soft, this buildup will turn to tartar or calculus. If these hardened tartar formations aren't removed regularly by a dental professional -- usually every six months or sooner if needed -- teeth can begin to decay near the gum line and the gums themselves will become inflamed. Inflammation of the gums, or gingivitis, then leads to periodontitis, or more serious gum disease. And at this point, roots of teeth are becoming exposed, teeth are increasingly decaying as enamel breaks down and bacteria gets inside tooth pockets and teeth, and tissues and nerves start feeling the pain of having their outer protections removed. Neglecting oral hygiene often leads to tooth, or dentin, sensitivity.
Unfortunately, trying too hard to keep teeth clean and to reverse damage by "making up for" poor brushing and flossing habits also makes teeth sensitive. Brushing too hard, using too much baking soda or other abrasives to clean, and whitening and attempting to rinse away teeth problems with strong concoctions designed to freshen breath and protect can do a lot more harm than good. Even brushing too often can be damaging [source: ADA].
We talked about the skin of the body earlier and how it is one of the first and best lines of defense against infection until it is compromised by cuts, abrasions or poor bodily hygiene leading to open sores or cracks, and the teeth are similar in this way. If you gently rub and wash skin with circular motions and slight pressure, blood circulates well, skin remains unbroken and moisture levels stay where they should be. Overdoing it with a loofah or stiff cloth to get rid of caked on dirt after a hard day of work or skipping a few too many days in the shower makes the skin dry, red and although mostly undetectable with the human eye, it also creates innumerable small cuts and abrasions in the protective layers of the skin. Over time, skin can break down and become sensitive. Not many people would use extra force to clean sunburned flesh or scraped knees, for instance, but using a firm toothbrush on sensitive teeth and gums is actually pretty similar and probably much more common. An instinct to save the teeth by getting them cleaner can make the roots and dentin much, much more sensitive and broken down.
Other tooth-sensitizing habits within our control include drinking acidic juices, sugar and carb-loaded soda and spicy foods, among others, without brushing afterward, allowing the corrosive agents to eat their way through the protective layers of teeth and gums. Alcohol is another culprit in getting access to our tooth nerves.
But it isn't, by any means, completely our fault if we develop sensitive teeth. Many factors are beyond our control, and sometimes, sensitivity happens despite our best efforts at doing no harm. We'll put the blame elsewhere, next.
Other Causes of Tooth Sensitivity
We can control a lot of what goes on in our mouths when we're healthy, but accidents, illness and the effects of aging can alter our teeth and gums quite suddenly or slowly over time. Some causes of tooth sensitivity outside of our control include:
- Trauma to the teeth -- An impact injury can crack teeth through the enamel, exposing the dentin and nerves.
- Aging -- Enamel wears down over time and gums can begin to recede. Periodontal, or gum disease, which exposes tooth roots, is more common as we age.
- Teeth grinding -- Whether a result of temporary stress or an ongoing joint dysfunction such as TMJ, the impact of teeth grinding against each other damages enamel, cracks teeth and dental work and can weaken gum tissues, all leading to nerve exposure and sensitivity.
- Addiction and eating disorders -- Heavy drinking and drug use (especially methamphetamines, or meth) not only erode teeth and damage gums on their own, but also lead to neglect of oral hygiene in many addicts. Bulimia and anorexia often involve forced vomiting, which brings strong digestive acids in contact with teeth, making them weak and sensitive.
- Illness and medications -- Diseases of the body can affect how well nutrients get absorbed and can lead to dental problems such as dry mouth. Diabetes is linked to tooth sensitivity and even gastrointestinal or stomach issues such as GERD bring acids up from the stomach through the esophagus, causing tooth erosion and pain. Medication also can cause dry mouth, and chemotherapy drugs, among others, can make nerves in the mouth very sensitive.
- Dental work and treatments -- Some individuals experience considerable tooth sensitivity from routine teeth cleanings, after getting braces and while undergoing gum disease treatments such as scaling and root planing.
If teeth are eroded or gums are receding, nerves are open to zaps of pain from air and hot and cold food and drinks. Sometimes nerve pain is ongoing even when the mouth is closed, empty and at rest. People with sensitive teeth can even begin to fear their favorite foods and opening up for a good laugh because they never know when it will hurt.
What can be done to ease or relieve the pain, and can anything prevent it? Next we'll look at desensitizing.
Relief for Sensitive Teeth
If you're experiencing tooth sensitivity, many over-the-counter toothpastes are effective. Using them, however, isn't a replacement for having a dental professional check your teeth and gums for signs of decay and gum inflammation. Sometimes, sensitivity points to a larger problem such as a tooth abscess, which is an infection requiring treatment with antibiotics, or other causes of pain that can worsen if not corrected. A dental assessment can help determine the causes of sensitivity and the best way to alleviate the discomfort.
According to the American Dental Association, sensitive teeth are very treatable. Readily available toothpastes such as Sensodyne contain an ingredient called potassium nitrate that alleviates symptoms by getting into the channels and blocking the nerve pain. Name brands Colgate, Tom's and Crest, among others, have similar products.
Sensitive formula toothpastes are most effective when used for several weeks so agents can build up in and on teeth to desensitize exposed areas of dentin and roots. Some oral rinses also deliver a desensitizing film to lessen pain. Using an ADA-approved toothpaste, a soft toothbrush and a treatment plan recommended by a dentist will increase the chances of finding products that work. If OTC toothpastes aren't effective, a dentist may try some office procedures such as high-concentrate fluoride applications or plastic-based root sealants. If these methods don't work, removing nerves and nerve endings through root canal procedures or devitalization by an endodontist may be necessary to relieve the pain [sources: ADA; Bartlett and Ide; Colgate].
Lifestyle changes can help as well. Sour and sweet foods, soda and acidic juices, and spicy sauces may need to be eliminated or avoided as much as possible, and simple measures such as using a straw to avoid having hot and cold beverages come in contact with teeth might bring a great deal of relief. It's hard not to be sensitive about sensitive teeth, but in most cases, we don't have to tough it out. When it comes to teeth, it's OK to say "Stop being so sensitive!" and to let yourself be desensitized.
- American Dental Association (ADA). "Sensitive Teeth." ADA.org. 2011. (Dec. 1, 2011) http://www.ada.org/3058.aspx
- Bartlett, D.W. & Ide, M. "Dealing with Sensitive Teeth." National Institutes of Health, NIH.gov. Jan. 1999. (Dec. 1, 2011) http://www.ncbi.nlm.nih.gov/pubmed/10752461
- BBC. "Skelton - Teeth." BBC.co.uk. 2011. (Dec. 2, 2011) http://www.bbc.co.uk/science/humanbody/body/factfiles/teeth/teeth.shtml
- Colgate-Palmolive Company. "What Causes Tooth Sensitivity?" Colgate.com. 2011. (Dec. 2, 2011) http://www.colgate.com/app/CP/US/EN/OC/Information/Popular-Topics/Sensitive-Teeth/article/What-Causes-Tooth-Sensitivity.cvsp
- Colgate-Palmolive Company. "What Is Tooth Sensitivity?" Colgate.com. June 26, 2006. (Dec. 1, 2011) http://www.colgate.com/app/CP/US/EN/OC/Information/Popular-Topics/Sensitive-Teeth/article/What-is-Tooth-Sensitvity.cvsp
- GlaxoSmithKline. "Sensodyne: Frequently Asked Questions." Sensodyne.com. 2011. (Dec. 2, 2011) http://us.sensodyne.com/FAQs.aspx
- Markowitz, K. & Pashley, D.H. "Discovering New Treatments for Sensitive Teeth: The Long Pathway from Biology to Therapy." National Institutes of Health, NIH.gov. April 2008. (Dec. 1, 2011) http://www.ncbi.nlm.nih.gov/pubmed/18321266
- National Library of Medicine (NLM). "Theradent." DailyMed, NIH.gov. May 2010. Dec. 2, 2011. http://dailymed.nlm.nih.gov/dailymed/drugInfo.cfm?id=35595