You must get a Dental Cleaning or tooth scaling done once every 6 months ideally. Visit a Dentist Near You routinely to ensure your teeth are healthy.
Yes, dental X-rays are safe as they are very low dose radiations. An X-ray will help your dentist to see things or signs of decay not visible to the eye otherwise.
The various options to replace a missing tooth include dentures, a fixed bridge and dental implants.
Tooth decay or dental caries is caused when food accumulating onto the tooth surface starts to ferment liberating acids which weaken the tooth and make is susceptible to bacterial attack. Ensure you visit a dentist near you to make sure that you do not have any teeth decay.