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Why does cold water hurt my teeth but warm water doesn't?

  1. Oct 26, 2015 #1
    Whenever I brush my teeth and I squish the water around in my mouth, I get an intense sharp pain in some of my top back teeth. I've been to the dentist several times and they say there's nothing wrong with my teeth. However whenever I drink warm water or squish warm water around in my mouth it doesn't hurt.

    So why does cold water hurt and warm water doesn't?
    Last edited: Oct 26, 2015
  2. jcsd
  3. Oct 26, 2015 #2


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    I am definitely no biophysicist, but here is my guess for what's going on:

    The inside of your mouth is already pretty warm, around 98.6##^{\circ}## Fahrenheit. The change in temperature for your teeth is probably much greater when you use cold water than when you use warm water. Also, when in contact with cold water, your teeth thermally contract - maybe they squeeze some nerves. On the other hand, when your teeth are heated, they expand. Perhaps they are not squeezing anything in this case, then.
    Last edited by a moderator: Oct 26, 2015
  4. Oct 26, 2015 #3


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    There are a number of treatments for sensitive teeth, some are available over the counter such as in toothpaste for sensitive teeth. If the sensitivity continues, I would go back to a dentist and insist that you really have sensitivity and to treat you for it, they have treatments that are better than what you can buy yourself.
  5. Oct 26, 2015 #4
    But why is it only cold water that hurts my teeth and not warm water? What is so special about cold water?
  6. Oct 26, 2015 #5


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    Perhaps this will help explain, apparently they are not 100% certain, but this hypothesis seems to be a reaonable explanation.

    [Brannstrom (1964) has proposed that dentinal pain is due to hydrodynamic mechanism, i.e., fluid force.[22] Scanning electron microscopic (SEM) analysis of “hypersensitive” dentin shows the presence of widely open dentinal tubules.[6] The presence of wide tubules in hypersensitive dentin is consistent with the hydrodynamic theory. This theory is based on the presence and movement of fluid inside the dentinal tubules. This centrifugal fluid movement, in turn, activates the nerve endings at the end of dentinal tubules or at the pulp–dentine complex.[21] This is similar to the activation of nerve fibers surrounding the hair by touching or applying pressure to the hair. The response of pulpal nerves, mainly Aδ intradentinal afferent fibers, depends upon the pressure applied, i.e., intensity of stimuli.[21] It has been noted that stimuli which tend to move the fluid away from the pulp–dentine complex produce more pain. These stimuli include cooling, drying, evaporation and application of hypertonic chemical substances.[23] Approximately, 75% of patients with DH complain of pain with application of cold stimuli.[23] In spite of the fact that fluid movement inside the dentinal tubules produces pain, it should be noted that not all exposed dentine is sensitive. As stated before, the “hypersensitive” dentin has more widely open tubules and thin/under calcified smear layer as compared with “non-sensitive” dentine. The wider tubules increase the fluid movement and thus the pain response.[6,7][/quote]

  7. Oct 27, 2015 #6


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    I have cold-sensitivity on several of my teeth, predominantly on one or two where I've had a filling put in to fill a cavity. I use a toothpaste that (used to) help reduce the sensitivity of my teeth, but its effects appear to have waned as of the past few months. I guess I'll just have to eat less ice cream. :cry:
  8. Nov 3, 2015 #7
    Same here. I used a sensitive reducing toothpaste for several years. In my case I've had an extensive set of amalgam fillings as this was common practice in New Zealand last century. I've been told that some UK dentists refer to this as the Australasian Trench. In my case increasing sensitivity was a symptom of cracks forming. I've been told this is partly due to repeated thermal expansion and contraction of the huge amalgams.

    As I entered my fifties, the toothpaste became less effective and pressure sensitivity started to become an issue. My dentist suggested taking preventative action by replacing the most at risk fillings with crowns over an extended period (one every 6 months). As a result I no longer suffer any sensitivity, and have thus far avoided the need for any root-canals or implants.

    When younger, I saw the excellent movie 84 Charing Cross Road, I had not realised that dental expenses featured there were so common in later life.
  9. Nov 21, 2015 #8


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    My dentist told me that if a tooth hurts with warm water, it may be an abscess caused by the death of the nerve. The warmth causes expansion inside the chamber which puts pressure on the nerve. Cold water will bring relief. But if cold or sweet causes pain, it tends to be a cavity.
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