Yes, these anatomical grooves are completely normal. It does not only provide a natural look, but these grooves actually aid in chewing and breaking down food to make it easier to digest and swallow. Hope this was helpful to you.
Sorry to hear you are in so much pain! It is difficult to diagnose without seeing your teeth or any x-rays. The best option would be to make an appointment with a dentist to see what is going on with your teeth. Best of luck to you.
It is definitely an option the majority of the time to close spaces with invisalign. At times a part of invisalign therapy is to shave down the sides of teeth minimally to allow for the teeth to move and shift to where they need to be. Although, this is not the case for you, the same principle would apply that the space could be closed and the previous portion of your tooth already shaved off is not a problem.
Yes, there can be some discrepancy in the tooth shade from the front to the sides. Also, lighting will not reach the sides of the mouth as much as the front teeth due the lips and cheeks casting shadowing and blocking light. Teeth whitening is an option if you are looking to lighten any of your teeth, but darker enamel is not necessarily a sign of any dental problems.
