You might think of your teeth as tools, like built-in knives and forks, but if they are mere tools, why do they feel pain and wouldn’t it be better if they could just (26)_____ under any condition? In spite of our (27)_____ discomfort, it turns out there’s a good reason our teeth are so sensitive. Tooth pain is a (28)_____ mechanism that ensures when a tooth is being damaged we’ll notice and do something about it.
If we eat something too hot or too cold, or if the tooth is worn down enough where the tissue (29)_____ is exposed, all of those things cause pain, and then the pain causes the person not to use that tooth to try to protect it a little bit more. So it’s really a protective mechanism more than anything else. If teeth didn’t feel pain, we might (30)_____ to use them in situations that damage them, and for humans, damaging (31)_____ teeth is a problem because, unlike crocodiles, we can’t (32)_____ them.
Teeth have three layers, only one of which—the innermost layer of the tooth—can hurt, as that layer of the tooth (33)_____ both blood vessels and nerves. Pain is the only feeling to which the nerves in that layer respond. Whereas people with tooth sensitivity may complain, for example, of tooth pain (34)_____ by heat or cold, the nerves in the inner layer don’t sense temperature. Rather, they feel pain, which may be (35)_____ with, say, drinking something very cold.
