Am I a bad mother? Is it too late to stop before cavaties develop?

My son has sensory integration disorder and some oral sensitivies in his mouth. He often times will chew on a chewy (it looks like a phone cord) for oral stimulation. This keeps him from biting. My son is severely Autistic, as everybody already knows. Sometimes I"ve been known to give him "dum dums", those small lollipops, when we go somewhere for a while. He really likes those. But I"m concerned because I already have a hard time brushing his teeth. I have to place my fingers in the very back of his mouth to open his mouth, while holding my legs on his arms, and then proceed to brush as fast as I can. This is very painful to my son trying to brush his teeth. And he will fight me tooth and nail, as he is very, very strong for a 3-year-old. Should I stop giving him these lollipops cold turkey, because he really really likes them, and I'm afraid that he will develop cavaties, if I don't stop. He will eat between 1-3 of them in a day. I usually only brush his teeth once a day, just because of the torture factor that he goes through with this process. I don't even want to think about trying to brush them at night when he's in a calm mood. I know I may sound stupid, but these are common problems among children with Autism having oral sensory needs. So am I a bad mother for allowing this and do you think he will develop cavities eating these, or should I just stop buying them, and if I stop now, he will be fine? He hasn't been into the lollipops for long, maybe about a month or so.