Urgent advice for gcses and university?

16 year old brother is 1-10 marks off a grade 6 in gcse edexcel higher maths. he wants to do dentistry at a prestigious university and then eventually do private orthodontics. nearly all top medicine/dentistry unis require a minimum of a 6 in maths, so he believes it’s unfair that he was so close. he’s already studying for his a levels and determined to get aaa+ (he wants to do bio chem and maths if they let him with a 5 in maths). could i have advice on this please and uni suggestions? thankyou.
Urgent advice for gcses and university?
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