Dear Tooth Checked,
First of all, you do not have a dental eyeball unless you have attended dental school nor a crystal ball to see the hidden future of your fragile teeth. Some anomalies are very evident and some can never be detected until something happens. Cracks can occur subgingival (under the gum tissue) and never cause a problem. Some may abscess and can be seen by a x-ray which would make things more obvious.
Secondly, an appointment made six months ago is confirmed always with a phone call and a postcard to the last phone number and address given to the dental office. The correct phone number and address are necessary for the recall system to work. It is the responsibility of the patient to update their address and phone number information in order to receive their appointment reminders. Responsibility is the key word. Thank you, Dr. Storm and Staff