Disturbed eruption of the lower second molar: clinical appearance, prevalence, and etiology.

Disturbed eruption of the second lower molar is a condition not often described in the dental literature. To study this aberration, 88 referred patients with 108 totally or partially impacted lower second molars were examined. The mean age of these patients was 15 years; 64 percent were male. A third molar was found adjacent to the affected second molar in 95 percent of cases. Local space shortage was seen in 90 percent of the cases. The prevalence of this disturbance overall is 1.5 per 1,000 individuals. Impactions in mesioangular and distoangular positions seemed to have been caused mostly by lack of space, whereas additional local factors had complicated many vertical impactions. Bite supervision should include early observance of the molar area for detection of disturbance in eruption of the lower second molar.