If teeth are normally formed, the enamel surfaces are quite hard and resistant to wear. Since the aligner material is resilient and quite a bit "softer" than the teeth, it is unlikely they would abrade the enamel surfaces. Enamel is vulnerable to softening (decalcification) when...
The material used for the aligners (or trays) with Invisalign is a resin polymer, or plastic. While I have yet to see someone exhibit an allergic reaction, it certainly IS possible (never say never). To be safe, traditional brackets and wires can be used.
You have asked a great question. In this context "overbite" means the vertical overlap of the front teeth. 100% overbite means that the upper front teeth cover 100% of the lower front teeth. In general 20% to 30% overbite is about normal. If one of the goals of your...