Evaluation dentoskeletal and soft-tissue changes of class II malocclusion treatment with two maxillary premolar, four premolar and nonextraction protocols

Author(s)

Tassiana Mesquita Simão

• Document type: Doctoral Thesis
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2010-10-01

Examining board members

Guilherme dos Reis Pereira Janson; Ana Claudia de Castro Ferreira Conti; Eduardo Alvares Dainesi; Jose Fernando Castanha Henriques; Dirceu Barnabé Raveli

• Advisor: Guilherme dos Reis Pereira Janson

Abstract

The objective of this investigation was to evaluate the posttreatment dentoskeletal and soft-tissue characteristics, mainly, the maxillary incisor position of Class II, division 1 patients treated nonextraction, with two maxillary premolar and with four premolar extraction protocols. A control group of normal occlusion was also employed. The sample of 120 subjects was divided into four groups, three experimental groups and one control group. Group 1 comprised 30 patients (19 girls, 11 boys) with initial and final mean age of 12.38 and 14.95 years, respectively, and treated without extraction. Group 2 comprised 30 patients (17 girls, 13 boys) with initial and final mean age of 12.68 and 15.28 years, respectively, treated with extraction of 2 maxillary premolars. Group 3 comprised 30 patients (15 girls, 15 boys) with initial and final mean age of 13.10 and 15.55 years, respectively, treated with extraction of 4 premolars. Group 4 comprised 30 individuals (15 girls, 15 boys) with a mean age of 14.93 years and with normal occlusion from the Burlington Growth Centre, Orthodontics Department of the University of Toronto Dental School, Canada. The initial and final occlusal features of the experimental groups were evaluated on dental casts by Peer Assessment Rating (PAR) and the final cephalometric characteristics of the sample were obtained in lateral cephalogram and compared using ANOVA. The results demonstrated that the maxillary showed a smaller length in group 3 than in group 1 and control group; greater vertical growth pattern and greater maxillary and mandible incisors extrusion in group 3 than in the other groups. The experimental group showed maxillary and mandible retrusion regarding the control group. The maxillary incisors were similar among the experimental groups; however they showed greater upright position in groups 2 and 3 than in the control group. The mandibular incisor presented greater buccal displacement in group 1 than the three groups. The overjet was smaller in experimental groups than in control group and the overbite was smaller in group 2 than in groups 3 and 4. The hard- and soft- tissue were similar in all groups. Therefore, the three treatment protocols were able to restrict the anterior displacement of the maxillary and were similar regarding the mandibular component, overjet, mainly, the maxillary incisor position. Besides that, these groups showed a satisfatory maxillomandibular relationship without impairing the facial profile regarding the normal occlusion group. (AU)

• FAPESP's process: 08/00208-2 - Evaluation of dentoskeletal and tegumental treatment changes in Class II, malocclusion with two upper premolar , four premolar extractions and nonextraction.
• Grantee: Tassiana Mesquita Simão
• Support Opportunities: Scholarships in Brazil - Doctorate