Nobody in his right mind would be pouring boiling water on his garden plants, or in the mouth of his pet, not to mention into the mouth of his child and yet people drink scalding coffee or tea and they eat food, which is so hot, they would not be able to hold it in their hand.
Coffee for a take-out is normally served in double paper cups or the cups with a styrofoam ring around the periphery, that is the only way you can carry it without burning your fingers, and yet people do not seem to care about exposing the tissues in the mouth and throat to the dangerously high temperatures!
Teeth also sustain damage from hot drinks and hot food; dental enamel cracks, fillings begin to leak because the filling materials have a different thermal expansion properties, as compared to the bone.
Another deadly effect from "heating" your teeth is "cooking" the tissues in the pulp chamber inside the tooth. Most people know that there is a "nerve" inside the tooth; it is actually not just the "nerve" but vascularized tissue, whose capillary network supplies nourishment to the tooth bone. This tissue, like any other one, would die if heated to the temperature of forty two degrees Celsius. People who expose their teeth to high temperatures, are thus running very high risk of "cooking" the tissue inside the pulp chamber; a tooth can be intact, with no visible signs of damage, and yet it is dead; quite obviously, such teeth are a source of infection in the body, they also represent a dental emergency, as you have to treat the root canal without much delay. Dead bone is very fragile, such teeth have to be crowned, since they can break, and if a fracture extends into any of the roots, then a dental surgery is unavoidable.
Often people eat food, which is so hot, it would burn the mouth, and so they hold it between their teeth till it cools down somewhat. People, who are this careless are likely to have at least some of their front teeth dead.
Hot foods and drinks are major causative factors behind mouth cancer, throat cancer and cancer of esophagus; stomach can also be burned with hot drinks and food. The body has to keep rebuilding the damaged tissues, while more is being burned every day, as the mouth is being scalded many times every day. These are "ideal" conditions for developing cancer.
As one can well imagine, cancers of the mouth and throat are not operable, the treatments "of choice" are radiation and chemotherapy. When I was doing my hospital practice as a nursing student, I had a patient with esophagus cancer, the treatment was to replace it with a section of his own colon. I do not know how long he lived after that, I do not even know if he survived the operation, but, as one can well imagine, that patient would have to live the rest of his life on liquid foods, as his new esophagus could not, obviously, produce peristalsis (rhythmical contractions which propel food towards the stomach).
An Internet search for "cancer [of] mouth", "cancer [of] throat" would fetch many pictures that can profoundly shock even the most carefree people.