Effect of Therapeutic Extraction on the Skeletal, Dental and Soft Tissue Relations. A Retrospective Cohort Study.

Objective: Therapeutic extraction to treat various malocclusion cases is frequently used in orthodontic treatment plans. The aim of this retrospective study was to assess and compare the effects of four first premolar extraction, upper first premolar extraction and non-extraction treatment plans on the anteroposterior and vertical skeletal relations, as well as their effects on the facial soft tissues. Materials and Methods: Lateral cephalograms of 75 patients who received a non-extraction treatment plan (GP I), four first premolar extractions plan (GP II) and upper first premolar extraction plan (GP III) were selected. Each group comprised 25 pre and post lateral cephalograms of skeletal class 2 hyperdivergent cases. A number of skeletal and dental anteroposterior, vertical and soft tissue parameters were measured using WebCeph online software. Comparison between the three groups was done using Kruskal-Wallis test followed by Dunn's multiple comparisons test. Results: There was insignificant change in the mandibular plane inclination and nasolabial angle across the three groups. In GP III, a significant decrease was recorded in SNA and ANB angles of 1.970 ± 3.74 and 1.10± 2.17 respectively. Sagitally, insignificant differences were found in the SNA and SNB angles across the three groups, with similar change (1.50 ± 0.57) in ANB angle in both GP I and GP III. Both extraction groups showed more flattening of the upper and lower lips compared to the non-extraction group. Conclusions: Therapeutic extraction of the first premolars had limited effects on the sagittal, anteroposterior and soft tissue relations.