[Root resorption of mandibular second molars by impacted third molars. A case report with some reviews].

A case is presented here in which mandibular third molars resorbed second molars bilaterally 4 years 9 months after orthodontic treatment was finished. The initial problem was open bite, which was treated by non-extraction followed by a period for observing the third molars. During that period, the mandibular third molars moved mesially to resorb the roots of the second molars. The injured second molars were, therefore, extracted and the third molars were uprighted. During adolescence, third molars are erupting. When the posterior space is not enough for the third molars, they often erupt buccally or lingually, or impact distally toward the second molars and cause root resorption. It is suggested that the third molars should be observed carefully till they erupt or are extracted.