Cause breakage? The silicone itself shouldn't be the cause of breakage, I wouldn't think. Silicone is essentially like coating your hair in wax. It's goal is to put a shield between your hair and the environment in order to accomplish the following goals:
1. Retain moisture
2. Avoid heat damage
3. Prevent tangles
4. Strengthen the strand

If anything, I would say that silicone would help do the opposite and prevent breakage. However, that's not to say I am recommending silicone based hair products. That's a hotly debated topic. All I will say is that in my personal opinion, silicones have some benefits but aren't right for everyone. If you are going to use products heavy in dimethicone, though, I suggest looking into a good clarifying shampoo to use at least once a month to prevent build-up.