Introduction. A borderline case is the one in which different clinicians disagree about the need of teeth extractions. Hypothesis. The decision to extract is not only determined by crowding. Aims. Identifying clinical and/or cephalometric variables that, together with crowding, determine the need of teeth extractions and its pattern. Assessing extraction cases predictive variables. Material and methods. Retrospective study of 147 patients who presented molar Class I, inferior crowding between 0 and –8 mm (–x = 5,5 mm) and occlusal stability, treated in the orthodontics service. The extraction group (n = 103), treated with four premolar extractions, was divided depending on the extraction pattern: first premolars (n = 45), second premolars (n = 31) and combinations (n = 27). The control group (n = 44) received non extraction treatment. Clinical and cephalometrical variables were analysed. Intergroup and intragroup results were compared. Results. The extraction group presented a more dolicofacial pattern (facial axis: –x = 86°; p < 0.005; anterior facial height: –x = 47,6°; p < 0.005), fewer interincisive angle (–x = 124,7°; p < 0.005) and more protrusion (–x = 3 mm; p < 0.005) and proinclination (–x = 25,2°; p < 0.005) of mandibular incisors. Midline deviation and labial incompetence were more frequent in this group. No significative differences were found in the intragroup comparison. Conclusion. Discrepancy is not the only variable determining the need of tooth extractions in borderline cases.
(Rev Esp Ortod. 2012;42(1):023-028)