There is really no reason for lip numbing for filler injections. It all depends on the technique. Personally, I have not used a topical anesthetic in 8 years. Pain and lip bruising are mostly the side effects of the past and should happen, if at all, only very occasionally. The injection techniques have evolved dramatically and yet, a "traditional" methods are still widely used. You can inject the majority of the fillers with a needle that is smaller than the one used for Botox injection. Another great option is to use a small cannula that, if used correctly, may give you almost magical results. So, discuss the techniques with your injector and go for the approach that makes you comfortable. Good luck!