There is no need to insult delboy-he is just asking a sensible question on what he needs to do to achieve a place in a dentistry course. lt isn't very encouraging to slate him for his grammar when he is trying to take positive steps to plan his career.
I would think that if you obtain the appropriate grades delboy you should be eligible for a place, although I am by no means sure of this. I do know you will need minimum of ABB to be eligible for any course and as you know dentistry is very competitive. Have a look at this site for guidance in general,
http://www.learndirect-advice.co.uk/helpwithyo urcareer/jobprofiles/profiles/profile426/. I would think you should look at universities that offer the course and contact the relevant course tutors directly to find out what your options would be and to answer your specific question about taking extra years to do A-levels.