the relative frequency of odontogenic tumors ( ots ) has been disputed due to controversies and confusion in the tumor taxonomy , subtyping and pleomorphism in its presentation . in the past , many studies based on 1971 and 1992 , world health organization ( who ) classifications studies were carried out in various parts of the world . to our knowledge , few studies based on latest edition ( 2005 ) of who classification have been reported . in this study histopathologic reports ( both odontogenic and nonodontogenic ) of biopsy specimens from 1997 to 2007 were retrieved and rediagnosed based on 2005 classification . we retrieved histopathology reports of the biopsy specimens from the university teaching hospital , benghazi , which is the only referral center in the entire eastern part of libya serving 1/3 ( 1.5 million ) of the entire libyan population to analyze all oral tumors . the relative frequency of ots in libyan population was analyzed and compared with previous reports . the ots were analyzed for frequency , sex , and site distribution . with regards to site distribution , the maxilla and mandible were divided into three anatomic regions : anterior , premolar , posterior . the data obtained was compared with the reports from various parts of the world , based on 1992 classification in the present study , 85 ots were retrieved , which constituted 12.6% of the 675 tumors and tumor - like lesions involving the oral and maxillofacial region . of the 85 ots , 84 ( 98.8% ) were benign and 1 ( 1.1% ) was malignant . the most common tumor found was ameloblastoma , which constituted 28.2% followed by keratocystic odontogenic tumor ( kcot ) ( 25.8% ) and odontoma ( 19.9% ) [ table 1 ] . frequency of odontogenic tumors ( 2005 world health organization classification ) table 2 shows age , gender , and site distribution for all ots . ots was present in the age range between 6 and 75 years with a mean age of 29.4 years . the peak incidence of ots was in the third decade ( 31.7% ) , with 74.1% of the patients in between 10 and 39 years . there were 28 ( 32.9% ) tumors in the maxilla and 57 ( 67% ) in the mandible ; 42.3% of the ots were located in the posterior region , ameloblastoma comprising 21.1% of those , followed by kcot ( 8.2% ) . age ( years ) , sex and site distribution of patients with odontogenic tumors in table 3 , the frequency of the ots was compared with the previous studies , according to 1992 who classification . percentage incidence of odontogenic tumors in various studies , based on 1992 world health organization classification there were six major changes compared to the 1992 who classification : ( 1 ) parakeratinised odontogenic keratocyst is classified as benign tumor derived from odontogenic epithelium and termed kcot . ( 2 ) adenomatoid odontogenic tumor ( aot ) originates from odontogenic epithelium but not from ectomesenchyme . ( 3 ) calcifying odontogenic cyst ( coc ) is divided into two benign and malignant groups . ( 4 ) clear cell odontogenic tumor ( ceot ) is considered malignant lesion and termed clear cell odontogenic carcinoma ( ccoc ) . ( 5 ) odontogenic carcinoma is not included . the incidence of ots in the sub - saharan african population is reported to be between 19 and 32% and in caucasians 1% . the relative incidence of ots of all the tumors and tumor - like lesions in this study was 12.5% , which suggests that ots are not uncommon in libyan population . in the present study , ameloblastoma was the most common tumor ( 28.2% ) , which is consistent with the nigerian european , and chinese studies kcot constituted the second ( 25.8% ) most common tumor followed by odontoma ( 19.9% ) . the frequency of odontomas was relatively high compared to other african studies , but low in comparison to american reports . the frequencies of ameloblastoma and odontoma are consistent with the report by olgac et al . there was an almost equal sex predilection in this study ( m : f = 1.2:1 ) , which was similar to nigerian studies , but in contrast to female preponderance from hong kong , chile , mexico , brazil , and estonia . ots showed a marked preference for mandible in this study ( 2:1 ) and nigerian series however , american and european studies showed a predilection for maxilla . the marked prevalence to mandible the frequency of ameloblastoma was between 11 and 24% in caucasians while among black africans , it accounts for 6699% . when 1992 classification was used , ameloblastoma constituted 38% of the ots in the present study . the peak incidence of ameloblastomas was in the third decade , and the mean age was 29 years , which concurs with other african findings . the male predilection observed in this series is in line with the nigerian study , but differs from studies from turkey and south america , in which female predominance was reported . the 2005 who classification considered parakeratinised odontogenic keratocyst as benign ot tumor derived from odontogenic epithelium due to its aggressive nature and recurrence rate , and it is now termed kcot . of the 32 okcs retrieved in total , 22 ( 68.8% ) were parakeratinised . the study by jing et al . reported 91.1% of the odontogenic keratocysts comprised parakeratinised epithelium ( kcot ) . kcot was the second ( 22.5% ) most common tumor , with a male female ratio 1.2:1 . the results were consistent with the chinese study , which was also based on the latest classification . the mean age of compound odontoma was 23.3 years and that of complex odontoma 17.7 years which are not in agreement with other reports , where the mean age of compound odontoma was lesser than complex odontoma . two cases of aot were reported , both in the maxilla and before the age of 30 . the occurrence of tumor in a younger age group was also shown in other reports . in 2005 , calcifying odontogenic cyst was reclassified into categories : calcifying cystic odontogenic tumor ( ccot ) , a benign cystic neoplasm characterized by an ameloblastoma - like epithelium with ghost cells that may calcify . dentinogenic ghost cells tumor ( dgct ) histologically constituting ameloblastic epithelium with mature connective tissue and ghost cells , in association with dysplastic dentin ; and ghost cell carcinoma which is a malignant variant of ceot and dgct . clear cell ot is now termed clear ccoc . in this study , there were six cases of ccot with a mean age of 28 years and the maxilla odontogenic myxoma was the second most common tumor in the sub - saharan population . in our study , odontogenic myxoma comprised 7% of all tumors and were similar to the frequency seen in previous reports . the tumor shows a predilection for mandible similar to the reports by nigerian series , but other reports have recorded predilection for maxilla . although most reports suggest a female predilection of the tumor , it is interesting to note that in our study odontogenic myxoma is seen predominantly in males ( 5:1 ) . ameloblastic fibroma constituted 2.3% of all ots , which was consistent with reports from other series , but not with that of estonian study ( 16% ) . other tumors seen in this study with low frequency are ceot , cementoblastoma , and central odontogenic fibroma . the incidence of malignant ots was significantly high in sub - saharan african series and chinese studies . our study reported one case of malignant tumor ( 1.1% ) , and when 1992 classification was used for comparison , the frequency was 1.5% . the rarity of the malignant tumors was in agreement with american and european series ( 0.11.1% ) . the incidence of ots in this libyan population is similar to studies from turkey and brazil , rather than aligning either to sub - saharan or caucasian populations . due to an altered pattern of incidence in select populations , further studies are encouraged to ascertain the similarities in the genetic pattern of different geographic locations and racial populations .
aims : the aim of this study was to determine the relative frequency of odontogenic tumors ( ots ) in an eastern libyan population based on the 2005 world health organization ( who ) classification , and also to compare the actual data with previous studies.materials and methods : we retrieved and analyzed 85 ots from a total of 675 tumors and tumor - like lesions of the oral and perioral structures , for gender , age , tumor site , and frequency . 
 the diagnosis was based on the most recent who ( 2005 ) classification of ots.results:ots constituted 12.6% of all oral / jaw tumors and tumor - like lesions . 
 ameloblastoma ( 28.2% ) was the most common type , followed by keratocystic odontogenic tumor ( 25.2% ) and odontoma ( 19.9% ) . 
 the male : female ratio was 1.2:1 , and maxilla : mandible ratio 1:2 . 
 the mean age of occurrence of tumors was 29 years with a peak incidence between 10 and 40 years.conclusions:ots are relatively common lesion in this libyan population , but the incidence of tumors is neither similar to caucasians nor sub - saharan population .