Ceramic and sapphire braces are made of a material whose hardness is comparable to that of enamel. If there is prolonged contact between a tooth and a brace of this kind (most often an upper tooth against a lower brace), you may notice the edge of the tooth wearing down and its shape changing. This kind of contact should not be allowed to happen, and it is eliminated either by filing down the brace or by placing bite-raising material to prop the bite open and limit it. Metal braces don’t cause this kind of wear, because metal is softer than enamel.
This answer is for general information. Your own case needs an examination by an orthodontist.