As I can see this is due to improper brushing Go to dentist for scaling then use floss regularly so that in future you can avoid this

If strains are extrinsic then go for scaling and polishing and if intrinsic filling can be done based on X-ray.

Check for vitality tests, visit your DENTIST

if stains are extrinsic then can be removed by scaling but if these stains are intrinsic  then treatment can be complicated somehow. You should visit to dentist for proper oral examination.

Seems like a combination of 1)Intrinsic stains cause due to fluorosis ,loss of vitality of tooth due to trauma or decay 2)Extrinsic stains due to plaque ,calculus, chromogenic bacteria.

Hello sir This photo is not clear. If the stains are from the childhood. Then fluoride paste is not recommended. If it's stains formed now then u can use fluoride toothpaste but it won't remove stains. Stains as to be treated. For extrinsic stains scaling can be done. For intrinsic stains u can go for veneering sir. Need to know more history

Sometimes there are stains which may be intrinsic ( inside)stains ,fluorosis or extrinsic (0utside ) stains .extrinsic stains, can be cleaned easily by a dentist .but extrinsic stains treatment can be more complicated.   

Hello Please visit the dentist for the cleaning

Hello, the stains you see are extrinsic stains, which can usually be removed by scaling and polishing. However, you will first need to undergo a clinical examination. Also, maintaining good oral hygiene is important to prevent them from recurring.

Hello, This looks like Regular stains. Please visit a dentist nearby and get your scaling done. If there's any cavity, please get fillings done. After the procedure you can start using Flouridated toothpaste.

Hi Go for a clinical examination, first determine whether the discoloration is extrinsic or intrinsic. If extrinsic, perform ultrasonic scaling and polishing to remove surface stains, followed by proper oral hygiene instructions and advice on avoiding staining agents (tea, coffee, tobacco, etc.). If the stains are intrinsic (such as mild fluorosis or enamel hypomineralization), consider microabrasion, bleaching, or composite veneers depending on the severity and your esthetic needs. A topical fluoride toothpaste or varnish can be used if enamel sensitivity or early demineralization is present. Get your Regular follow-up and maintenance are essential to monitor the condition.

Hi, Visit a dentist and get a clinical examination. Get an x-ray for the tooth.

Hello Seems like fluorosis but need a closer look