Comparison of the outcomes of the lower incisor extraction, premolar extraction and non-extraction treatments
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Eur J Orthod (2012) 34 (6): 681-685. doi: 10.1093/ejo/cjr064
Abstract
The aim of this retrospective study was to
evaluate the treatment outcome of lower incisor extraction and to
compare it with
premolar extraction and non-extraction treatment.
The sample consisted of 60 subjects with Class I malocclusion and
moderate
crowding. The sample was separated into three
groups: extraction of a lower incisor group, extraction of a four first
premolar
group and a non-extraction group. All groups
involved 13 girls and 7 boys with a total of 20 patients. The Peer
assessment
rating (PAR) index was applied to a patient’s
pre-treatment (T1) and post-treatment (T2) dental casts. T1 dental casts
were
also used for determining Bolton discrepancy.
One-way analysis of variance and post hoc Tukey HSD tests were used for statistical analysis. For the mean percentage PAR score reduction for each group, there was
one significant difference seen between the lower incisor extraction group and the non-extraction group (P
= 0.047). For the mean anterior ratios, there were significant
differences among premolar extraction group versus non-extraction
group (P = 0.042) and non-extraction group versus lower incisor extraction group (P = 0.000). For the mean overall ratios, there were significant differences among the premolar extraction group versus lower
incisor extraction group (P = 0.048) and the non-extraction group versus lower incisor extraction group (P
= 0.001). Orthodontic treatment without extraction has a better
treatment outcome than the four-first premolar extraction
and single lower incisor extraction protocols in
Class I cases with moderate to severe mandibular anterior crowding.
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