What defines permanent dentition and when does it appear?

Permanent dentition is defined as the stage when all the permanent teeth have erupted and are fully present in the oral cavity. This usually occurs by around age 12, marking the transition from the presence of primary teeth to a complete set of permanent teeth.

During this stage, individuals typically have 28 permanent teeth, following the loss of primary (or baby) teeth. The first set of permanent molars usually erupts around the age of 6, which is often referred to as the "six-year molars." The completion of permanent dentition happens when the last of the permanent teeth, including second molars and any remaining incisors, have fully erupted and any primary teeth that were still present have been shed.

The age of 12 is significant as it signifies that most of the permanent teeth have taken their place in the mouth, providing a complete transition from primary to permanent dentition.