I am also not a dentist, and it's impossible to make judgements based on what you have told us. Dentists are highly trained professionals who know far more than I do. They must reach, and keep, high standards. If you're not happy, there are ways to raise concerns.
1. All dental practices have their own query or complaints procedures. Speak to them first.
2. There is an NHS complaints procedure.
3. Similarly there is a Dental Complaints Service for private treatment.
The General Dental Council can take action whenever a dental professional's ability, behaviour or health means it's not suitable for them to continue working. The GDC looks carefully at every allegation they receive. Hopefully in your case, the problem can be resolved by ( 1. ).
This link should help :- http://www.gdc-uk.org/Membersofpubli...s/default.aspx