Efficiency of Class II subdivision malocclusion treated with three premolar and four premolar extractions

Author(s)

Taiana de Oliveira Baldo

• Document type: Master's Dissertation
• Press: Bauru.
• Institution: Universidade de São Paulo (USP). Faculdade de Odontologia de Bauru (FOB/SDB)
• Defense date: 2011-01-20

Examining board members

Guilherme dos Reis Pereira Janson; Marcos Roberto de Freitas; Marcia Masi

• Advisor: Guilherme dos Reis Pereira Janson

Abstract

The aim of this study was to compare the efficiency of Class II subdivision malocclusion treatment with symmetric extractions and asymmetric extractions. Therefore, it was selected from over 4,000 documentations from the files of the Orthodontic Department at Bauru Dental School, University of São Paulo, a sample of 71 patients with complete Class II subdivision malocclusion. Then, this sample was divided into two groups, with the following characteristics: Group 1, consisted of 40 patients treated with four premolar extractions and with initial mean age of 13.37 ± 1.31 years (minimum of 10.25 years and maximum of 15.91 years) and Group 2 consisted of 31 patients treated with three premolar extractions (two maxillary premolar and one mandibular premolar on the Class I side) with initial mean age of 14.44 ± 2.83 years (minimum of 10 years and maximum of 24.25 years). To compare the efficiency of the treatment protocol applied to each group, occlusal results of treatment were assessed on dental casts using the TPI and PAR occlusal indexes, while time spent in the treatment of each group was calculated from the clinical charts. Amount of initial and final midline deviation and improvement of midline deviation correction were also evaluated. Efficiency was calculated as the rate between occlusal improvement, as assessed by TPI and PAR occlusal indexes, by the treatment time. Initial and final occlusion rates, treatment time, efficiency of the treatment protocols of the groups and variables of midline were compared with t tests, adopting a significance level of 5%. The results showed a statistically significant difference only in final amount of midline deviation and in improvement of midline deviation correction: Group 2 showed a smaller final and better correction of midline deviation. Although the efficiency did not provide a statistically significant difference between the groups, the greater improvement of midline deviation correction in group 2 than in group 1 shows that the treatment protocol with three premolar extractions has advantages in relation to the treatment protocol with four premolar extractions. (AU)

• FAPESP's process: 09/06928-0 - Class II subdivision treatment efficiency in three premolar extractions and four premolar extractions protocols
• Grantee: Taiana de Oliveira Baldo
• Support Opportunities: Scholarships in Brazil - Master