It an aligner cracks and you just started using it, you can go back to your last aligner instead. If your new aligner has arrived and it’s almost time to use it, you can probably start with the new one right away. In either case, a cracked aligner will not work properly and must be replaced. So if the old or the new aligner are not options, immediately speak with your dentist at Carmichael’s Marconi Dental Group to determine exactly what to do next.