Soft-tissue changes in Class II malocclusion patients treated with extractions: a systematic review

Background: Concerns about the effects caused by premolar extractions on the soft-tissue profile have motivated many investigations in different malocclusions.

Objectives: To evaluate the cephalometric facial soft-tissue changes after orthodontic treatment with premolar extractions of Class II division 1 malocclusion subjects.

Search methods: Electronic databases PubMed, Web of Science, Embase, and Scopus were searched.

Selection criteria: Abstracts that appeared to fulfil the initial criteria (premolar extraction; cephalometric soft-tissue analyses/changes) were selected. The full-text original articles were then retrieved. Their references were also hand-searched.

Data collection and analysis: By consensus of two researchers, the articles that fulfilled the selection criteria and quantified facial soft-tissue changes were individually analysed. Some methodological flaws were identified and some articles were excluded. The studies were rated according to the type of study, sample description and homogeneity, malocclusion severity, consideration of confounding factors, validity of the method, and statistical analyses.

Results: Heterogeneous information about malocclusion severity before treatment was found in most articles. Statistically significant soft-tissue changes reported included nasolabial angle (NLA) increasing from 2.4 to 5.40degrees in 2-premolar extraction protocol and from 1 to 6.84degrees in 4-premolar extraction protocol. Retrusion of the upper and lower lips were also verified, with less retraction of the lower lip in 2-premolar extraction groups.

Conclusions: When Class II division 1 malocclusion is treated with premolar extractions, the NLA increases and the lips are retracted. However, there is less retraction of the lower lip in the 2-maxillary premolar extraction protocol.