Go for RCT with capping

Hello. You require an x-ray of the tooth. The tooth appears to be decayed. Depending on the extent of spread of cavity, you will either require a (1) restoration (filling) of the tooth or a (2) root canal treatment, followed by a crown placement. Also, There are calculus (tartar) and plaque deposits on your teeth. Calculus or tartar is a form of hardened dental plaque. It is caused by precipitation of minerals from saliva and gingival crevicular fluid (GCF) in plaque on the teeth. You are advised to undergo Scaling and polishing (professional teeth cleaning) to maintain your oral hygiene, Keep your gums healthy and firm. Visit a dentist for definitive diagnosis and treatment

Clinically it looks like you need a root canal treatment but an x-ray is required first.

The tooth looks decayed. Clinical examination is necessary. An Xray might be required to check the depth of it.