Comparing outcomes of mandibular incisor extraction, premolar extractions, and nonextraction
Ileri Z, Basciftci FA, Malkoc S, Ramoglu SI. Comparison of the outcomes of the lower incisor extraction, premolar extraction and non-extraction treatments. Eur J Orthod 2012;34:681-5
The typical approach to treating Class I crowding involves one of 2 methods: extracting 4 premolars or nonextraction treatment. The orthodontic literature includes extensive documentation and comparison of these methods. The literature has, however, focused less on the unconventional treatment method in which a mandibular incisor is extracted. In a retrospective study, these authors sought to compare the outcomes of this alternative approach with the 2 more traditional methods. They examined 60 Class I adolescent subjects, who were divided into 3 groups: mandibular incisor extraction, 4 premolar extractions, and no extractions. The decision whether to extract was based on, among other factors, severity of crowding, profile, and Bolton discrepancy. All subjects had the same appliances and mechanics throughout treatment. The final treatment outcomes were evaluated with the peer assessment rating. By using the patient’s dental casts, 2 ratings were given for each patient: pretreatment and posttreatment. The higher the rating, the greater the deviation from a harmonious occlusion. The results were as follows. The mean percentages of reduction in peer assessment rating ratings were 80.3% for mandibular incisor extraction, 87.7% for 4 premolar extractions, and 91.2% for nonextraction treatment. Although the mandibular incisor extraction method met high standards for finished treatment, the authors attributed the smaller change in the mandibular incisor extraction group to increased overjet and overbite. The authors acknowledged the benefits of using a mandibular incisor extraction pattern, including obtaining a functional occlusion and enhancing esthetics with minimal manipulation. Still, based on their findings, they concluded that the best overall treatment outcomes for Class I crowding came from a nonextraction approach, followed by a 4 premolar extraction approach and then a mandibular incisor extraction plan.
Reviewed by Shira Lazebnik
Posterior crossbite and temporomandibular disorders
Thilander B, Bjerklin K. Posterior crossbite and temporomandibular disorders (TMDs): need for orthodontic treatment? Eur J Orthod 2012;34:667-73
An essential part of orthodontic treatment planning is treatment timing. Although most orthodontic treatment is motivated by esthetic interests, certain conditions might prompt early intervention based on prophylactic concerns. One such condition is a posterior crossbite and its potential association with temporomandibular disorders (TMD). A search of the literature shows different conclusions about whether this association exists. Variations in study designs and age groups, as well as imprecise definitions of TMD and crossbite, could have prevented clarity on this topic. The authors pointed out that crossbite can fall into 3 categories: skeletal transverse discrepancies, dental arch-width discrepancies, and crossbites with a functional shift. The authors conducted a systematic review of the literature with a special focus on discovering a potential relationship between a particular sign or symptom of TMD and the presence and type of posterior crossbite. As in other reviews, the authors found positive and negative correlations between TMD and crossbite. Many authors expressed interest in the several TMD variables, but type of crossbite was usually ignored. Three articles mentioned functional crossbites. In these studies, joint sounds, clicking, muscle tenderness, and headache were significantly associated with this type of crossbite. A laterally displaced mandible results in asymmetrical activity of the masticatory muscles; this persists even at rest. The altered condyle-fossa relationship can also affect the adaptive response in a growing patient, eventually creating a significant skeletal asymmetry if not corrected. The authors concluded that a posterior unilateral crossbite with a functional shift indicates a need for treatment.
Reviewed by Alexander Oldroyd