[Radiological characteristics of the cyst-like lesion of condyle in temporomandibular joint by cone beam computed tomography].

OBJECTIVE: To analyze the radiological characteristics and classifications of the cyst-like lesion of condyle in temporomandibular joint (TMJ) by cone beam computed tomography (CBCT). METHODS: The study was conducted retrospectively on TMJ images from 194 patients who underwent CBCT examinations. Location, size, amount, surrounding bone trabecula, cortical bone white line of cyst-like lesion, and the overall condition of the condylar bone were evaluated. According to the overall condition of the condylar bone, the cyst-like lesion of condyle were divided into typesⅠand Ⅱ. The location, size, amount, surrounding bone trabecula, and cortical bone white line of the two types of cyst-like lesions were compared. RESULTS: In 198 condylars of 194 patients, cyst-like lesions were detected in the left side of 94 patients, in the right of 96 patients, and in both sides of 4 patients. The size of lesions ranged from 1.2 mm to 13.5 mm, with an average size of (3.4+/-1.5) mm. Half of the cyst-like lesions were located underneath the anterior lateral cortical bony layer (99 condylars, 50.0%). Most cyst-like lesions were solitary (149 condylars, 75.3%), while 62.6% (124 condylars) were surrounded by continuous bony white lines. Bone sclerosis could be observed in 160 condylars (80.8%). A total of 132 condyles (66.7%) were accompanied by changes in late-stage osteoarthrosis, while the others were only accompanied by early-stage osteoarthrosis (10 osteoarthrosis, 5.1%) or showed no evidence of osteoarthrosis (56 osteoarthrosis, 28.3%). Statistical difference were observed in the location, amount, and surrounding bone trabecula of the two types of cyst-like lesions. TypeⅠcyst-like lesions had more frequent and bone sclerosis than type Ⅱ, whereas type Ⅱ cyst-like lesions occurred more on condylar internal or condyle neck than typeⅠ. CONCLUSIONS: The pathogenesis and mechanism of the two types of cyst-like lesions may be different from each other.