title: Extraction treatment of a class II division 2 malocclusion with mandibular posterior discrepancy and changes in stomatognathic function.
abstract: This case report describes the successful extraction treatment of a Class II division 2 malocclusion with mandibular posterior discrepancy and a congenitally missing maxillary lateral incisor on the left side. The posterior space in the mandibular arch was small, and the mandibular second molars were impacted, with distal tipping. The discrepancies in the maxillary and mandibular arches were resolved by extraction of the maxillary lateral incisor on the right side and the mandibular second premolars on both sides. The mesial movement of the mandibular first molars occurred appropriately, with the second molars moving into an upright position. A lip bumper was used with a preadjusted edgewise appliance in the maxillary dentition to reinforce molar anchorage and labial movement of the retroclined incisors. Despite the extraction treatment, a deep bite could be corrected without aggravation as a result of the lip bumper and utility arch in the mandibular dentition. Thus, an Angle Class I molar relationship and an ideal overbite were achieved. The occlusal contact area and masticatory muscle activities during maximum clenching increased after treatment. The maximum closing velocity and the maximum gape during chewing increased, and the chewing pattern changed from the chopping to grinding type. The findings in the present case suggest that the correction of a deep bite might be effective for improving stomatognathic function.
authors.affiliation: a Assistant Professor, Department of Orthodontics, Field of Developmental Medicine, Health Research Course, Graduate School of Medical and Dental Sciences, Kagoshima University, Kagoshima, Japan.
authors.forename: Kunihiro
authors.initials: K
authors.lastname: Nagayama
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Tomonari
authors.forename: Fumiaki
authors.initials: F
authors.lastname: Kitashima
authors.forename: Shouichi
authors.initials: S
authors.lastname: Miyawaki
mesh_terms: D000848:Anodontia / Q000628:therapy; D001641:Bicuspid / Q000601:surgery; D001732:Bite Force; D002508:Cephalometry / Q000379:methods; D002648:Child; D004576:Electromyography / Q000379:methods; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007180:Incisor / Q000002:abnormalities / Q000601:surgery; D008312:Malocclusion, Angle Class II / Q000628:therapy*; D008334:Mandible / Q000473:pathology*; D008409:Mastication / Q000502:physiology*; D008410:Masticatory Muscles / Q000502:physiology; D008963:Molar / Q000473:pathology; D009119:Muscle Contraction / Q000502:physiology; D052280:Orthodontic Anchorage Procedures / Q000295:instrumentation; D016382:Orthodontic Appliance Design; D057887:Overbite / Q000628:therapy*; D010347:Patient Care Planning; D014081:Tooth Extraction / Q000379:methods*; D014087:Tooth Movement Techniques / Q000295:instrumentation / Q000379:methods; D014095:Tooth, Impacted / Q000628:therapy
keywords: Class II division 2; Lip bumper; Posterior discrepancy; Stomatognathic function