title: [MRI analysis of the effect on mandibular retrusion with anterior disc displacement treated by using Herbst appliance].
abstract: Objective:To investgate the effect of Herbst appliance on the growth and remodeling of the temporomandibular joint (TMJ) in class Ⅱ patients with mandibular retrusion by using MRI.Methods:Between December 2010 and October 2014, 12 class Ⅱ patients (11-16 years old) with mandibular retrusion were chosen. The patients were divided into two groups. The control group included 7 patients (14 joints) with normal disc condyle relationship and the anterior disc displacement (ADD) group included 5 patients (10 joints) with anterior disc displacement. The MRI images of TMJ were measured, including condylar height, joint space index and disc position ratio, before and after the treatment.Results:The condylar height of the patients in the control group was significantly increased (P<0.001) after treatment, and no significant difference in joint space index (P=0.821) and disc position ratio (P=0.146) was found. The joint space index of the patients ([-14.70±8.82]% and [4.90±11.35]%) in ADD group changed significantly (P<0.001) after treatment, and no significant difference in condylar height (P=0.294) and disc position ratio (P=0.120) was found.Conclusions:The normal disc condyle relationship was beneficial to the reconstruction of the condylar process, and the increase of the condylar height. The condyle moved forward in patients with anterior disc displacement after treatment.
authors.affiliation: Department of Cranio-Maxilla Facial Science, Center of Cranio-Facial Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine & Shanghai Key Laboratory of Stomatology, Shanghai 200011, China (Present address: Department of Pediatric Dentistry, Shanghai Stomatological Hospital, Shanghai 200001, China).
authors.forename: X
authors.initials: X
authors.lastname: Yu
authors.affiliation: Department of Cranio-Maxilla Facial Science, Center of Cranio-Facial Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine & Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors.forename: J Q
authors.initials: JQ
authors.lastname: Liu
authors.affiliation: Department of Cranio-Maxilla Facial Science, Center of Cranio-Facial Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine & Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors.forename: L J
authors.initials: LJ
authors.lastname: Yuan
authors.affiliation: Department of Cranio-Maxilla Facial Science, Center of Cranio-Facial Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine & Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors.forename: L X
authors.initials: LX
authors.lastname: Mao
authors.affiliation: Department of Cranio-Maxilla Facial Science, Center of Cranio-Facial Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine & Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors.forename: M
authors.initials: M
authors.lastname: Zhu
authors.affiliation: Department of Cranio-Maxilla Facial Science, Center of Cranio-Facial Orthodontics, Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine & Shanghai Key Laboratory of Stomatology, Shanghai 200011, China.
authors.forename: B
authors.initials: B
authors.lastname: Fang
mesh_terms: D016723:Bone Remodeling; D016022:Case-Control Studies; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008312:Malocclusion, Angle Class II / Q000000981:diagnostic imaging / Q000628:therapy*; D008335:Mandibular Condyle / Q000000981:diagnostic imaging; D017289:Orthodontic Appliances, Functional; D063173:Retrognathia / Q000000981:diagnostic imaging / Q000628:therapy*; D013704:Temporomandibular Joint / Q000000981:diagnostic imaging; D019224:Temporomandibular Joint Disc / Q000254:growth & development / Q000293:injuries*
keywords: Anterior disc displacement; Malocclusion, Angle class Ⅱ; Orthodontic appliances, functional; Temporomandibular joint disk