Abstract
We encountered a rare case of an impacted mandibular right second primary molar with the succeeding premolar located above the impacted primary molar. The patient was a 6-year, 9-month-old girl at her first visit. No signs of redness or swelling were noted in the gingiva on the impacted tooth. Radiographic examination revealed a calcified body on the upper and distal side of the impacted primary molar. The second premolar germ showed distal inclination and was located on the upper, mesial and lingual side of the affected primary molar.The crown of the impacted primary molar was fenestrated and the calcified body was removed. Four months later, the primary molar was fenestrated again and traction was started. Because the primary molar did not erupt in spite of the traction, the primary molar was removed under general anesthesia. At that time, the tooth germ of the second premolar was preserved intact. Approximately 1 year later, the second premolar appeared in the oral cavity. At the age of 12 years and 6 months, the affected premolar was aligned within the lower dental arch and its root showed good development on the radiographic photograph.Although the etiology could not be clearly concluded, it was speculated that the process of the migration of the second premolar into the inter-radicular position of the predecessor was disturbed by unidentified causes, and that the second primary molar was impacted because of retention of the primordium of the second premolar.It was indicated that we could preserve a permanent tooth in case of an impacted primary molar with an inverse successor germ which showed good condition and position. It should also be pointed out that the early detection and treatment of impacted primary teeth are important since the influence of impaction on a successor is very serious although the frequency of impaction of primary teeth is very low.
