Hi sir...
Your picture shows you have mild deposits in your teeth....
Eventhough you brush well and twice daily there is always some inaccesible area that needs to be cleaned by professional dentists
You need to go for cleaning(scaling and polishing) by dentists...followed by teeth whitening procedure(Teeth bleaching) which will makes your teeth 2 shades brighter...
Next Steps
kindly visit nearby dentist for furthur conaulation and management..
Health Tips
Do cleaning(scaling) for every 6 months....
Do brush and floss your teeth twice daily...
Do rinsing with mouth wash twice daily after food...