A case of horizontal double impaction of the right mandibular first and second molars is described. A 21-year-old man with pain at the right mandibular region visited our hospital. Radiographic examination showed horizontal impaction, with the mandibular second molar lying over the first molar. These teeth were extracted under general anesthesia. The right half of the lower lip was paralysed after the operation, but symptoms disappeared subsequently. We attribute impaction in this patient to local causes because he had no noteworthy medical history and no abnormalities of the other teeth or jaw. Abnormal location of a tooth germ was therefore apparently involved.
