Your best answer would be from your dentist after an examination.
A few possible answers:
That is just the way it is right now, and with time the sensitivity will disappear
Clenching and or grinding of the teeth, especially during sleep
Using drinks that have a low Ph. (This includes all sodas, sports drinks, many of the bottled water drinks, fruit drinks, fruit juices, and similar.)
You have recently had treatment for gum disease
You are using a strong bleaching solution to whiten your teeth
Your best information will come after an examination and consultation with your dentist.
There are so many possible causes. Do visit your dentist. I am sure sure he will give you some answers. Some of the possibilities include gum recession, abfractions exposing the underlying dentin, erosion due to acid, bruxism, and clenching.
Hope this helps.
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The reason is mainly thin enamel, which can be due to use of a hard brush, or our eating habits, i.e., too much acid in the food, grinding our teeth or systemic problems like acid reflux of our stomach. In your case, I think you are grinding you teeth so your lower teeth have abrasion, loss of enamel their for sensitivity. I think if you start using a night guard, it will help you.
In adults, generally, as we age, we tend to lose bone density, especially around the front teeth, so the roots of the teeth feel the temperature changes more. Also, gum recession causes more root exposure, be mindful that roots don’t have the enamel layer which is the protective shield for the coronal portion of the tooth. Roots of the teeth are more sensitive to heat and cold. Several things can cause gum recession:
-Grinding your teeth
-Restorations that are too close to the bone level
You need to have a clinical exam to determine what is the reason for your teeth sensitivity and receive the proper treatment.