Could you specify what grade (numbers) you got for Bio, Chem, Maths, and English (Lan+Lit)? Because most dental universities look at those grades specifically when determining acceptances.
If you look online there are universities that we like to call GCSE-heavy or GCSE-light. GCSE heavy universities include Cardiff and King's and Belfast, among others, where the GCSE scores more heavily influence the outcome of your interview and beyond. GCSE light universities include Plymouth or Liverpool, where the GCSE scores are less important.
However, unless you are eligible for contextual there is a minimum of usually 6/7 - 9 GCSE grades, translates to around Bs to A*s in the old system, for BiochemmathsEng, for all schools across the board. I think Manchester has new sort of requirements/admissions processes that are coming in this year so that is worth checking out as well. Hope this helps!