One-hundred and twenty-six cases of mandibular ameloblastoma, consisting of 111 primary and 15 secondary cases, were analyzed. The correlation among tumor characteristics, treatment and prognosis was discussed.
1. In the anterior group, patients were relativery old. Most tumors were radiographically demonstrated to be of honeycomb or multilocular type, and the majority histologically revealed follicular pattern showing Ishikawa Type I or II.
2. In the molar/retromolar group, patients ranged in age from the second to fourth decades. Over half of the tumors were of unilocular type radiographically and revealed plexiform pattern showing Type III. Honeycomb or mixed type were rare in this region.
3. The majority of the cases involving impacted teech were seen in the second or third decades and the site was consistently confined to the molar/retromolar region. Cases involving impacted tooth were not seen in the anterior region. These findings suggest that the tumor occurs in the molar/retromolar region at an earlier age than in the anterior region and that the distinct radiographic findings in each of these regions are caused by different structures of bone trabeculae.
4. In regard to capsule invasion of the tumor, the overwhelming majority of unilocularplexiform-type and unilocular-Type III lesions were of shallow invasive type. Growth was characterized by expansion. However, extracapsular invasion should be considered in other combinations of types because tumor invasion tended to be deep.
5. Regardless of histologic type, bone marrow invasion was seen in all cases of honeycomb and mixed type. Even in the cases of uni-or multi-locular type, bone marrow invasion should be considered when the tumor is follicular type showing Type II.
6. Recurrence rates in cases followed up for more than 3 years were 0/14 for patients undergoing mandibular resection, 0/13 for partial resection, 8/55 for enucleation followed by curettage, and 1/18 for cryosurgery.
7. Enucleation followed by curettage is used in uni-or multi-locular type, and in mixed or honeycomb type in combination with partial resection.
8. The indications for cryosurgery are the same as for enucleation followed by curettage.
9. Partial resection is used to treat relatively confined honeycomb type.
10. Fenestration is used to treat cystic tumors when the inferior border of the mandible is extensively affected.
11. Mandibular resection is employed in cases where the tumor causes extensive destruc-tion of the inferior border of the mandible, except in unilocular type.
12. Thirteen cases regarded to be unicystic ameloblastoma occurred in the second or third decades. All cases involved impacted teeth and revealed plexiform type showing Type III. Enucleation followed by curettage or cryosurgery was employed as treatment and no signs of recurrence were noted.
