Band 1 Treatment 
Treatment includes exam, radiographs which are clinically neccessary, scale and polish of clinically indicated areas. It also includes diagnosing and further treatment planning/advice. 
Band 2 Treatment 
Treatment includes all band 1 treatment, any fillings, advanced scaling for gum disease (perio), extraction of teeth and root canal therapy. Lab-work such as additions to dentures are also within this band. 
Band 3 Treatment
Treatment includes both band 1 and 2 treatment, any construction of dentures, inlays/onlays and crown or bridgework - only which is considered to be clinically necessary.
Free Treatment
This only applies if stitches have to be removed, denture repair (without impressions) & halting blood loss. For any work which is still under guarantee. 
Urgent Treatment 
For urgent treatment you pay the band 1 charge but if further work is needed then you may need to pay an additional charge 
For further information visit the NHS webpage