The posttreatment anteroposterior position of the mandibular incisors apparently can influence the facial profile. According to Holdaway, the most frequent comment heard in criticism of orthodontics comes from parents of prospective patients who do not like the changes in upper lip position that they have observed in some orthodontically treated patients. Since there is a relationship between root surface area and anchorage potential, the choice of which mandibular teeth to be extracted may have a direct effect on the amount of anterior segment retraction.
The extraction of 2 mandibular premolars usually gives more than enough space to align the mandibular incisors. Orthodontic closure of the residual space may result in the retraction of the mandibular anterior segment. This retraction may be favorable in the orthodontic treatment of Class III malocclusion, whereas it is usually unfavorable in Class II malocclusions. There is little information available on prediction of the amount of incisor retraction that can be expected during the closure of the mandibular premolar extraction spaces, and on the difference between the outcome with extraction of the first or second premolars.
Do we have any reliable predictions and recommendations concerning the treatment results following extractions of mandibular second versus first premolars when it comes to: (1) amount of mandibular incisor retraction; (2) long-term stability of the treatment results; (3) profile changes?—José M. Llamas, Sevilla, Spain