Thanks for your quick response. I actually do not have any scores below a 18. (PAT: 22, QR:22, RC:20, Bio: 22, GC:21, OC:19). The only category that I am actually very good at but surprisingly did really bad in was OC. That is why I was thinking about retaking it and generally improve all the scores specially OC. But as you mentioned there is a risk of getting a lower score. However, UCLA has been my dream school and been wanting to apply there but with a 21 I am not sure I would have a shot. Would my chances still be really low if I have a 3.8, with about 700 hrs of volunteering, 300 hrs shadowing, dental research lab at UCI (been published), dental assisting, and board member of other orgs? Im sorry for going on and on I just want to see how my application would be looked at as a whole.