title: Temporomandibular joint changes after activator appliance therapy: a prospective magnetic resonance imaging study.
abstract: The aim of this prospective clinical and magnetic resonance imaging study was to analyze the effect of 1-year Activator (Yi-fan Dental Co., Shanghai, China) treatment in internal anatomical relationships of the temporomandibular joint (TMJ) complex, including the condyle-disc relationship, condyle-fossa relationship, condylar height change, disc length change, and morphologic change of the glenoid fossa. The study was composed of patients with class II division 1 malocclusion (11 girls and 13 boys) who underwent 1-year Activator treatment. All the patients were in the acceleration or peak phase of the pubertal growth spurt. Magnetic resonance imaging in closed-mouth position and lateral cephalometric radiographs before and after 1 year of Activator treatment were analyzed metrically. Overall, condylar height showed a significant increase (P < 0.001), and the eminence angle decreased (P = 0.037). TMJ disc length has no statistically significant change before and after treatment. A slight advancement (P = 0.041) was found in the sagittal condylar position. A significant backward movement (P = 0.04) was shown in the sagittal disc position. Our results showed that the disc is not impaired by Activator therapy; it seems possible that adaptive remodeling, including a shallower glenoid fossa and increased condylar height, was seen after treatment.
authors.affiliation: Department of Oral and Cranio-maxillofacial Science, Shanghai Ninth People's Hospital, School of Medicine, Shanghai Jiaotong University, Shanghai, PR China.
authors.forename: Xuhui
authors.initials: X
authors.lastname: Ma
authors.forename: Bing
authors.initials: B
authors.lastname: Fang
authors.forename: Qinggang
authors.initials: Q
authors.lastname: Dai
authors.forename: Yunhui
authors.initials: Y
authors.lastname: Xia
authors.forename: Lixia
authors.initials: L
authors.lastname: Mao
authors.forename: Lingyong
authors.initials: L
authors.lastname: Jiang
mesh_terms: D000202:Activator Appliances; D000293:Adolescent; D002508:Cephalometry / Q000379:methods; D002648:Child; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008312:Malocclusion, Angle Class II / Q000473:pathology / Q000628:therapy*; D008335:Mandibular Condyle / Q000473:pathology; D011446:Prospective Studies; D013704:Temporomandibular Joint / Q000473:pathology*; D019224:Temporomandibular Joint Disc / Q000473:pathology