Hi sir...
Even you beush twice daily there is always some inaccesible areas in our mouth that needs to be cleaned(scaling and polishing) by dentists...
scaling and polishing removes extrinsic stains like coffee,tea, soft and hard deposits(plaque and calculus)
To make the teeth brighter you can go for teeth whitening procedure(Tooth bleaching)
Next Steps
kindly visit nearby dentist for furthur consultation and management
Health Tips
BDo brushing and flossing twice daily....Do rinsing with mouth wash twice daily