It can be due to harsh brushing or overbrushing or use of dental abrasives. Worn off teeth also cause sensitivity.

May be an internal crack or other thing. Go and visit a Dental surgeon. your case need clinical examination. For the time being you can try sensitive toothpaste. Avoid very cold an hot food.

Hi You may need to visit a dentist to have a look at it clinically and get a X-ray done if recommended. There are many things that cannot be diagnosed online and this is one of that.

Hie .. need to evaluate it clinically also.. since it could be a fracture line. Or any internal crack .. need and thorough examination of the same..

You can visit a dentist where in he can check for any kind of intervention needed by taking an x-ray and physical examination .. there are certain remineralisation and sensitivity toothpastes available u can use them twice at least for a month to appreciate a visible difference.. avoid too hot and too cold food items also keep gap when u consume hot and cold things

Hello May be thr s internal crack .so u have to visit clinic ,doctor ll take Xray .thn we can tell exact treatment for ths