"I have a missing tooth. Should I replace it?"
Yes. You should absolutely replace a missing tooth.

Depending on its location, a missing tooth can have a profound impact on the appearance of your smile. This is, however, far from the largest concern. When one or more teeth is missing, a whole host of oral health issues can follow.

TMJ, temporomandibular joint disorder, is the name given to a group of disorders that can impact the comfortable and proper alignment of the jaw. The underlying cause of TMJ is not always known, though it may be linked to:
TMJ disorder, also abbreviated TMD, is a condition that causes a number of painful or uncomfortable symptoms. One of the main causes of TMD is a misaligned jaw, which can happen after certain types of dental work. It can also occur due to missing or damaged teeth, which dental work can help to repair.