Treatment times of Class II malocclusion: four premolar and non-extraction protocols

Abstract

The purpose of this study was to retrospectively compare the treatment times of Class II division 1 malocclusion subjects treated with four first premolar extractions or a non-extraction protocol and fixed edgewise appliances. Eighty-four patients were selected and divided into two groups. Group 1, treated with four first premolar extractions, consisted of 48 patients (27 males and 21 females) with a mean age of 13.03 years and group 2, treated without extractions, consisted of 36 patients (18 males and 18 females) with a mean age of 13.13 years. Group 2 was subdivided into two subgroups, 2A consisting of 16 patients treated in one phase and 2B consisting of 20 patients treated in two phases. The initial and final Treatment Priority Index (TPI), initial ages, initial mandibular crowding, and treatment times of groups 1 and 2 were compared with t-tests. These variables were also compared between group 1 and the subgroups with analysis of variance followed by Tukey's tests. The treatment times for groups 1 and 2 and subgroups 2A and 2B were 2.36, 2.47, 2.25, and 2.64 years, respectively, which were not significantly different. Treatment times with non-extraction and four premolar extraction protocols are similar.

Factors influencing treatment efficiency:

“…Many studies have reported that treatment duration was longer in extraction treatment, [6][7][8][9] but there were also studies that showed no difference. [10][11][12] Studies have shown that missed appointments, 8,13 bracket failure, 10,14 poor elastic wear, 8,10 and poor oral hygiene 8 can affect treatment duration.…”

Esthetic perception of facial profile after treatment with the Thurow appliance

“…1,2 An infinite variety of appliances are available for the orthopedic correction of Class II malocclusion; these include both intraoral and extraoral appliances. 3,4,5,6 Among the intraoral orthopedic appliances,…”

Treatment efficiency of Class I four-premolar and Class II malocclusion two maxillary premolar extraction protocols

“…2,5 Malocclusion treatment protocol also plays a role in determining treatment time in complete Class II malocclusion treatment. [2][3][4] It has been shown that treatment time is smaller, with better occlusal outcomes in complete Class II malocclusion treatment when performed with two-maxillary premolar extractions than when treated non-extraction or with four premolar extractions. [1][2][3] It has been speculated…”

“…3 Treatment time in 4-premolar extraction and non-extraction protocols of complete Class II malocclusions are similar. 4 Consequently, it is speculated that the reason for the greater treatment success rate and efficiency, and the smaller treatment time in the 2-maxillary extraction protocol compared to the other two is because posterior teeth Class II anteroposterior discrepancy does not have to be corrected and consequently smaller patient compliance in using removable devices is necessary. [1][2][3]5,6 When Class I malocclusions treated with 4-premolar extractions were compared to complete Class II malocclusions, also treated with 4-premolar extractions, the results demonstrated better occlusal results and greater occlusal changes in the first group, corroborating this speculation.…”