The fate of impacted lower third molars after the age of 20. A four-year clinical follow-up.

Seventy dental students (mean age: 20 years) with 130 asymptomatic, non-ectopic, impacted mandibular 3rd molars were followed for 4 years. At the initial visit 26 were impacted in soft tissue, 30 were partially impacted in bone, and 74 were completely impacted in bone. The following items were registered at each visit: regional pocket depths, signs and symptoms of pathology, degree of impaction, presence of upper 3rd molar. No signs or symptoms of pathology were observed in any of the subjects at the 2 visits. The 4-year visit revealed that 49 3rd molars had been removed, the reason being pericoronitis or caries in 30%, mild symptoms in 39% and for prophylactic reasons in 31%. Of the remaining 81 3rd molars: 71% of the soft tissue impactions, 25% of partial bony impactions, and 8% of complete bony impactions showed complete and normal eruption. The remaining 3rd molars were either static or had advanced in the degree of eruption. It is concluded that non-ectopic, impacted 3rd molars in the given age group may have a chance to completely erupt. The treatment for asymptomatic impacted 3rd molars in young adults, therefore, might be observation instead of prophylactic removal.