Dear Sir/Madam,

My dentist trimmed my metal crown as it was too high. After that, I notice that there is a hole-like dent and it is not the same metal colour as the rest of the crown. According to my dentist it is the inner layer of the crown.

Is my crown too thin to offer protection over my crack tooth? What is this inner layer made of? Is it safe that it exposed? How do I know that it is not a tiny hole that can allow micron bacteria to pass into the crown?

Thank you.