bifid mandibular condyle is an uncommon anomaly with an unclear origin , which was first described in 1941 by hardlicka . the condylar head is divided into two partially or completely separated lobes by a rift or a deep groove . the separating groove can be oriented anteroposteriorly or mediolaterally to determine the spatial relationship of the heads . several theories exist about the origin of bmc , mainly suggesting traumatic or developmental origin [ 24 ] . if so , the broken condylar head will be displaced anteriorly due to the function of the lateral pterygoid muscle . gradually , a new head will grow up over the mandibular neck , in response to the functional demands with an anteroposterior orientation between the two heads . some believe that extended remaining of a fibro - vascular tissue over the developing condyles during the fetal period may result in bmc formation . although the mediolateral type of bmc is considered to be developmentally formed , some exceptions with traumatic origin have been reported . there is also a concept that only anteroposterior division of the condyles can be considered as a true bmc ; bmc is believed to play a role in some cases of temporomandibular joint disorder ( tmd ) , and joint symptom . on the other hand , radiographic appearance of bmc can mimic vertical condylar fractures , which confuses the physicians in cases of trauma to the face . thus , differential diagnosis is important in cases of trauma to the face and tmd . most cases of bmc are discovered accidentally during routine dental radiographic examinations , more commonly on panoramic views taken for other dental purposes [ 2,3 , 10 ] . there is still a need for more epidemiologic research on the incidence and probable role of bmc in general health . considering the availability of only a few reports on bmc three - dimensionally , this study was designed to evaluate the incidence of bmc in a south iranian population using cbct since cbct typically imposes a lower dose to patients compared to conventional radiography and computed tomography . this cross - sectional study was performed to assess the frequency of bmc and condylar head orientation on the transverse plane based on 425 cbct scans of paranasal sinuses in shiraz , iran . these cbct scans had been ordered as part of preoperative records for patients seeking rhinoplasty in an otolaryngology clinic . all cbct scans were obtained in upright position , using a newtom vgi scanner ( qr srl , verona , italy ) , in a 1515 field of view ( fov ) and standard resolution mode ( 0.3 mm voxel size ) . presence of space occupying lesions within the tmj area and lack of demographic information were considered as the exclusion criteria . only the cases in whom , both condyles were within the fov of cbct scans were included . the cbct scans were reviewed in nnt station ( qr srl , verona , italy ) by an experienced oral and maxillofacial radiologist . horizontal angulations of each condyle were determined by measuring the angle between the long axis of the condyle in the axial cross - section with the largest mediolateral dimension and an imaginary horizontal line ( fig . the left and right condylar heads were evaluated for presence of bifidity separately in the axial , coronal and sagittal planes . considering the condylar head orientation , true sagittal and coronal cross - sections were prepared at a thickness of 1 mm with 0.5 mm interval , over the largest mediolateral dimension of the condyle in the axial plane . the ethics committee of shiraz university of medical sciences approved the study and informed consents were obtained of all the participants . horizontal angle of a bifid left mandibular condyle on a transverse plane based on the axial cross - section . ab : horizontal line ; ac : the long axis of condyle spss software version 17.0 ( chicago , il , usa ) was used for data analysis . p - value less than 0.05 was considered statistically significant . frequency of bmc was compared between the left and right sides and between males and females using t - test . spss software version 17.0 ( chicago , il , usa ) was used for data analysis . p - value less than 0.05 was considered statistically significant . frequency of bmc was compared between the left and right sides and between males and females using t - test . the cbct records of 309 patients including 170 females ( 55% ) and 139 males ( 45% ) with a mean age of 29.439.7 years were entered in the study . the bmc was detected in 14 of them ( seven females and seven males ) , which comprised 4.53% of the total population ( figs . 2 and 3 ) . coronal cross - sections ( 0.5 mm thickness ) of the cases with ( a ) unilateral and ( b ) bilateral bifid mandibular condyles ( a ) axial , ( b ) corrected coronal and ( c ) corrected sagittal cross - sections of a case with right condylar head bifidity there was no significant difference in the incidence of bmc between males and females . eleven bmcs ( 3.56% of the population ) were unilateral , while bilateral condylar head bifidity was detected only in three cases . five unilateral cases were detected on the right side and six in the left side . the mean horizontal angulations of the condyles in normal individuals were calculated to be 22.66 versus 24.024.33 in bmc cases , implying no significant difference ( p=0.64 ) . similarly , there was no significant difference in the mean horizontal angulation values between men ( 23.25.8 ) and women ( 22.215.96 ) . since bmc may play a role in tmds or be mistaken for a condylar fracture , its differential diagnosis is of great importance . many epidemiologic studies have been conducted to estimate the real incidence of bmc all over the world , with a wide variability in results . most of the researches on bmc incidence were conducted on panoramic views , since it is a wide - spread , low cost , relatively low radiation dose , and easy to access radiographic technique , which visualizes a large volume of dental and supporting structures , including the rami and condyles . besides , a large number of people have already taken panoramic views for dental purposes , which can be used in epidemiologic studies as a pre - existing sample source . unfortunately , there are some serious limitations with the panoramic technique in this regard . due to superimpositions partial bmcs are hard to detect on panoramic views and mediolateral bmcs may be seen as anteroposterior ones , if the condyles horizontal angulations are large enough . the great discrepancy in the results of studies performed on panoramic views cho and jung believed that panoramic views either under- or over - estimated the incidence of bifidity . on the other hand , there is no universally accepted protocol to diagnose bmc on panoramic views , and judgments are subjective . since the introduction of cbct , dental imaging improved by versatile abilities of this three - dimensional imaging modality . yet , relatively low doses of radiation are delivered to patients and images are prepared in a really short time by a single rotation of the machine . deleting superimpositions brings the chance to observe the anatomical structures of interest precisely , and multi - planar images enable the physician to evaluate the interested structure in proper plane . as the operator can observe the condyles conspicuously , the probability of false positive and false negative diagnoses is significantly reduced , although the need for a standard scale to classify the severity of separations of the heads still exists . the cbct imaging is not used as widely as the panoramic views because of the nature of this technique . thus , the existing source of cbct records is slightly different from the normal population compared with panoramic images . the incidence of bmc in the current study was slightly higher than that in previous reports on the same population , but considering the advantages of three - dimensional imaging , it is negligible . most researchers believe that the incidence of bmc is increasing , as more radiographic examinations of higher quality are becoming available [ 35,7 ] . about 78% of cases were unilateral , and female to male ratio was 3 to 1 . evaluated 10,200 panoramic views and reported an incidence of 0.3% for bmc in a turkish population . reported the prevalence of bmc to be 0.52% in turkey , using panoramic radiographies as the screening tool . later , employing ct scan images , they reported a higher rate of about 1.82% in the same population . using cbct records , cho and jung compared the prevalence of bmc in asymptomatic and symptomatic subjects with tmj problems and no traumatic history and found no significant difference between them . they concluded that the presence of bmc would not lead to any tmj symptoms or cause osseous changes . we have already reported a high rate of bmc ( 3.5% ) in an iranian population   while in the current study , we found that 4.53% of cbct records revealed bmc in patients of the same population . the new rate , this difference can be attributed to the advantages of cbct that eliminates superimpositions in the images of the condyles . this finding is in accordance with the results of sahman et al , who reported a higher rate for bmc in ct records compared to panoramic images in the same country . it is worthy to mention that the lack of conspicuous criteria to diagnose bmc on panoramic images may be less important for cbct scans , because of higher reliability of multi - planar images provided by this modality . similarly , we believe that this will improve the agreement between different observers , and reduces the need to employ multiple observers in such studies , which requires the inter - observer agreement to be in an acceptable level . in most studies , the ratio of unilateral cases of bmc to bilateral form is about 3 to 1 . the results of the current study are compatible with this ratio , using a three - dimensional imaging modality ( nearly 4 to 1 ) . our results ( seven females and seven males ) , are also in accordance with the afore - mentioned mean female to male ratio for bmc prevalence , which is about 1.3 to 1.0 . however , menezes et al . reported a much higher prevalence in females ( 3.5 to 1.0 ) . finally , we believe that panoramic views face some limitations in detection of bmcs although they provide opportunities for screening purposes . oblique forms and partial bifid condyles are hard to discover using panoramic and other conventional imaging techniques . should the angulations of the condyle in the transverse plane are large enough , the mediolateral form of bmc may be diagnosed as an anteroposterior type . more advanced imaging techniques should be ordered , at least for symptomatic cases of bmcs or when treatment plans are to be conducted [ 3,4 , 7 ] . last but not least , cbct imaging may be an invaluable modality , considering its low dose of radiation ( compared to ct scan ) , the short time needed ( compared to magnetic resonance imaging ) , and high reliability of the produced images . the prevalence of bmc in the studied population was 4.53% , which was slightly higher than that in previous reports . no significant difference was detected between males and females , sides and condylar horizontal angulations of patients with normal and bifid condyles .