We have attempted clinico-statistical observation on 415 cases of benign tumors during past 10 years period from 1976 to 1985. Results obtained were as follows:
1) The 415 cases consisted of three groups, 59 odontogenic tumors, 302 non-odontogenic tumors and 54 salivary gland tumors (1.1:5.6:1). There were 161 males and 254 females, a 1:1.6 sex ratio.
2) Histopathologically, 28 cases (47.5%) of odontogenic tumors were diagnosed as ameloblastoma, 106 cases (35.1%) of non-odontogenic tumors as hemangioma and 42 cases (97.8%) of salivary gland tumors as pleomorphic adenoma.
3) The age at onset of symptoms revealed a perdilection for second and fourth decades (mean age: 34.3 years) as whole, and as to each group, odontogenic tumors for second and third decades (mean age: 24.7 years), non-odontogenic tumors for second and fifth decades (mean age: 34.6 years) and salivary gland tumors for under second and sixth decades (mean age: 43.0 years).
4) The age at first visit revealed a perdilection for fourth and fifth decades (mean age: 38.0 years) as a whole, and as to each group, odontogenic tumors for second and third decades (mean age: 28.9 years), non-odontogenic tumors for fourth and fifth decades (mean age: 38.4 years) and salivary gland tumors for sixth and over eighth decades (mean age: 46.6 years).
5) The duration of symptoms ranged from 1 to 3 years as a whole, and as to each group, under 1 month in odontogenic tumors, from 1 to 3 years in non-odotogenic tumors and also in salivary gland tumors.
6) The chief complaints were swelling in 320 cases (82.3%), pain in 33 cases (8.5%) and further exact examination in 20 cases (5.1%).
7) As a whole, the prevalent locations were the tongue (28.6%), followed by the mandible (13.2%) and the lips (11.6%), Odontogenic tumors occured only in the maxilla and the mandible, non-odontogenic tumors in the tongue, the lips and the buccal mucosa and salivary gland tumors in the palate and the parotid regions.
8) Of the removed 286 tumors, 72 tumors (26.9%) were sized between 10 and 20mm, 66 tumors (24.6%) between 5 and 10mm and 64 tumors (23.9%) between 20 and 40mm.
9) The most common treatment in this series was surgical excision except for fenestration (7 cases) and mandibulectomy or maxilloectomy (5 cases) of ameloblastoma.