For several generations now, dental treatment of third molars has been based on clinical impressions rather than on published scientific data, said Matthew Dennis, DDS, in an issue of the Journal of the Michigan Dental Association. But, as he noted, "questions about third-molar management are beginning to be answered."
Impacted third molars, because of the lateness of their emergence, should always be evaluated for removal or observation. most impactions involve arch length that is less than total tooth mass, resulting in inadequate space for eruption to occur.
The average age for eruption of third molars is 20, but some eruptions can occur as late as 25. Predicting eruption is, Dennis said, an inexact science, requiring radiographic as well as clinical evaluation.
"Even when symptom-free, two-thirds of young adult subjects were found (by the clinical trials) to have periodontal pathology in their third-molar regions," wrote Dennis regarding indications for third-molar removal, including findings in the American Association of Oral and Maxillofacial Surgeons' Third Molar Clinical Trials that show an association of third molars and periodontal disease.
Dennis said that the trials suggest that the inaccessible third-molar anatomy can harbor periodontal pathogens in up to 80% of patients with third-molar symptoms." "A large review of population and clinical studies with more than 8,000 subjects showed that patients with third molars had a worsened periodontal status on other teeth in the quadrant over those patients without third molars." Other conditions that may have greater incidences associated with third-molar impactions are pericoronitis and caries
Journal of the California Dental Association 02, 2012