Unilateral delayed eruption of maxillary permanent first molars: four case reports.

Delayed eruption or impaction of permanent teeth is one of the severe problems that can occur during the mixed dentition period. These conditions can occur in any permanent tooth, but the incidence of delayed eruption of the permanent first molars, especially maxillary permanent first molars, is very low. Johnsen found only one case of delayed emergence of a maxillary first molar as a result of local etiologic factors in a review of the records of 1032 young people ranging in age from 8 to 18 years. Dachi and HowelP examined 1685 sets of radiographs at the University of Oregon and found no case of impacted permanent first molars. Grover and Lorton found only one case of an unerupted maxillary first molar in their survey of the panoramic radiographs of 5000 Army recruits ranging from 17 to 26 years of age. Kramer and Williams examined 3745 panoramic radiographs of oral surgery patients, and found three cases of an impacted mandibular first molar but no impacted maxillary first molar cases. Permanent first molars are known as the "key teeth" in occlusion, and it is very important that the delayed permanent first molars be guided to the correct position in the dental arch. We encountered four cases of unilateral delayed eruption of maxillary permanent first molars at the Pedodontic Clinic of Niigata University Dental Hospital. We diagnosed the patients as having delayed eruption if either more than one year had elapsed since the antimere had erupted fully or it did not erupt at all. According to the research carried out by the Japanese Society of Pedodontics in 1988, the mean age at die time of eruption of the maxillary permanent first molars is 6 years 8 months ± 8 months for Japanese boys ]4 Fig 1. Case 1. Panoramic radiograph showing a radiolucentarea surrounding the crown of the unerupted maxillary right permanent first molar. > Fig 2. Case 1. Photomicroghaph of the excised gingiva IH&E, original mag. 50x1. There are numerous small island or cords of odontogenic epithelium amond the mesenchymal fibrous tissue. and 6 years 7 months ± 8 months for Japanese girls. Fenestration of the gingiva was performed surgically in each patient and occlusal guidance by traction was used for one. This paper presents the clinical and histopathological findings in these four cases of unilateral delayed eruption of maxillary permanent first molars.