[Treatment using the Lehman apparatus in patients with malocclusion in light of teleradiologic tests and dental arch measurements].
The aim of this study was to assess the usefulness of Lehman's appliance for the management of distocclusion and to establish indications and contraindications to its use. The mean duration of treatment was also determined and compared to such in similar form of malocclusion treated with other types of functional appliances. Linear measurements were performed on dental plaster casts before and after treatment. Cephalometric analysis served to establish the mechanism of Class II correction (skeletal or dentoalveolar) and to reveal any increase in mandibular length caused by Lehman's appliance. The material consisted of thirty-three Class II patients (18 girls and 15 boys), aged 9 to 15 years, treated successfully with Lehman's appliance for distocclusion. Dental plaster casts and lateral cephalograms were obtained at the beginning and end of treatment. Improvement in occlusal relationship in the molar, canine and incisor segments was the result of dental and skeletal changes. Metric analysis of dental casts before and after treatment showed that active treatment was associated with an increase in transversal dimensions of the upper arch ranging from 1.8 to 2.4 mm. Overbite and overjet decreased considerably. Anterior length of upper arch was reduced significantly in boys only and was accompanied by distraction and transition from a V-shaped to U-shaped type of arch. These changes helped to harmonize transversal dental relationship of both arches and improved conditions for functional skeletal base adaptation. Treatment with Lehman's appliance improved the intermaxillary relationship and led to a decrease in the ANB angle attributable to a change in the SNA angle in girls and the SNB angle in boys. The mandibular reaction in girls with Class II/2 was interesting: the SNB angle increased considerably, indicating "unblocking" of the mandible. Changes in the vertical skeletal relationship were limited to a minor reduction in the index. Maxillary incisors moved little, but mandibular incisors showed significant proclination. The present findings demonstrate an additional increase in total mandibular length achieved with Lehman's appliance. This important effect contributed to a successful treatment of Class II malocclusion. Nevertheless, it should be remembered that this growth process depends on other factors, such as age, growth potential, growth pattern, and duration of appliance use. Average duration of treatment was 15 +/- 5.2 months in girls and 17.1 +/- 7.1 months in boys. In the case of girls, treatment in skeletal Class I was shorter than in skeletal Class II; the contrary was true in boys. Duration of treatment was shorter in patients with orthognathic type of face, irrespective of gender. Patients with deep vertical relationship showed a better prognosis in terms of duration and effects of treatment.
Katedry i Zakładu Ortodoncji Pomorskiej Akademii Medycznej w Szczecinie, al. Powstańców Wlkp. 72, 70-111 Szczecin.
Hanna
H
Bielawska
D000293:Adolescent; D002508:Cephalometry; D002648:Child; D000075202:Contraindications; D003724:Dental Arch / Q000473:pathology*; D003735:Dental Casting Technique; D005260:Female; D006801:Humans; D008297:Male; D008310:Malocclusion / Q000534:rehabilitation*; D008334:Mandible / Q000000981:diagnostic imaging / Q000473:pathology; D016382:Orthodontic Appliance Design; D017289:Orthodontic Appliances, Functional; D011379:Prognosis; D011859:Radiography; D012737:Sex Factors