Class II Division 1 malocclusion treatment with extraction of maxillary first molars: Evaluation of treatment and post-treatment changes by the PAR Index.

OBJECTIVE: To investigate occlusal result and post-treatment changes after orthodontic extraction of maxillary first permanent molars in patients with a Class II division 1 malocclusion. SETTING AND SAMPLE: Retrospective longitudinal study in a private practice, with outcome evaluation by an independent academic hospital. Ninety-six patients (53 males, 43 females) consecutively treated by one orthodontist with maxillary first permanent molar extraction were studied, divided into three facial types, based on pre-treatment cephalometric values: hypodivergent (n = 18), normodivergent (n = 21) and hyperdivergent (n = 57). METHODS: Occlusal outcome was scored on dental casts at T1 (pre-treatment), T2 (post-treatment) and T3 (mean follow-up 2.5 ± 0.9 years) using the weighted Peer Assessment Rating (PAR) Index. The paired sample t test and one-way ANOVA followed by Tukey's post hoc test were used for statistical analysis. RESULTS: PAR was reduced by 95.7% and 89.9% at T2 and T3, respectively, compared with the start of treatment. The largest post-treatment changes were found for overjet and buccal occlusion. Linear regression analysis did not reveal a clear effect (R-Square 0.074) of age, sex, PAR score at T1, incremental PAR score T2-T1, overjet and overbite at T1, and facial type on the changes after treatment (incremental PAR score T3-T2). CONCLUSIONS: The occlusal outcome achieved after Class II division 1 treatment with maxillary first permanent molar extractions was maintained to a large extent over a mean post-treatment follow-up of 2.5 years. Limited changes after treatment were found, for which no risk factors could be discerned.

Extraction of maxillary first permanent molars in patients with Class II Division 1 malocclusion.

INTRODUCTION: Our objectives were to assess treatment outcomes in Class II Division 1 patients who were treated orthodontically with extraction of the maxillary first permanent molars and to describe the changes in their facial profiles. METHODS: This was a prospective, longitudinal, 1-group outcome analysis in a private practice, with outcome evaluation by independent observers at an academic clinic. One hundred consecutively treated patients were enrolled prospectively and treated by 1 orthodontist. The inclusion criteria were white, Class II Division 1, sagittal overjet of > or =4 mm, extraction of maxillary first permanent molars, no missing teeth or agenesis, maxillary third molars present, and 1-stage full fixed appliance treatment. Standardized lateral cephalometric radiographs were made before and after active treatment. Occlusal outcome was scored on dental casts by comparing pretreatment and posttreatment casts with the peer assessment rating (PAR) index. Backward regression analysis was used to explain the soft-tissue changes on the basis of dental changes and the soft-tissue characteristics. RESULTS: The mean reduction in weighted PAR score was 89.9% (SD, 0.9). During treatment, the lower lip retruded 1.6 mm (SD, 1.7) relative to the esthetic line. The nasolabial angle became 2.1 degrees (SD, 7.0) more obtuse during treatment. Overjet reduction and initial upper lip thickness could explain 15% of the variation in upper lip position. The changes in the position of the mandibular incisor relative to the Point A-pogonion line and initial lower lip thickness could explain 23% of the variation of lower lip position. CONCLUSIONS: Orthodontic treatment involving extraction of the maxillary first permanent molars has a good treatment outcome. Extraction of the maxillary first permanent molars has only a small effect on the soft-tissue profile.

Does fixed retention prevent overeruption of unopposed mandibular second molars in maxillary first molar extraction cases?

BACKGROUND: The objective of this study was to investigate whether multistranded fixed retainers prevented overeruption of unopposed mandibular second molars in maxillary first molar extraction cases. METHODS: The panoramic radiographs of 65 Class II Division 1 Caucasian Whites (28 females, 37 males) consecutively treated with bilateral maxillary first molar extraction and the Begg technique, and with records taken after treatment (T1) and in retention (T2), were withdrawn from private practice records. After appliance removal, mandibular second molars were retained with sectional wires till at least T2 in case of lack of occlusal contact with the antagonist. The subjects were assigned to study-retention and control-nonretention groups based on the retention status of mandibular second molars. Radiographic analysis was carried out to determine inclination of mandibular molars and the resulting movement of second molar centroids. Parametric and nonparametric tests were performed to assess the changes between T1 and T2. RESULTS: No statistically significant differences in molar inclination were observed between groups and timepoints (P > 0.05). There were no statistically significant differences in molar movement percentages (P > 0.05) irrespective of whether fixed retention had been used or not. CONCLUSIONS: No significant eruption occurred in unopposed mandibular second molars bonded with fixed sectional retainers compared to molars partially occluded with the antagonists without fixed retention. Given the study limitations, fixed retention should be considered with caution in restricting tooth overeruption in unopposed molars.

Overjet correction and space closure mechanisms for Class II treatment by extracting the maxillary first molars.

OBJECTIVE: To analyze the mechanism of overjet correction and space closure when treating Class II Division 1 patients by extracting the maxillary first molars. PATIENTS AND METHODS: A total of 100 prospective, consecutively treated Class II Division 1 patients (45 female, 55 male; 10.5-17.2 years old). Standardized lateral cephalograms prior to and after treatment were evaluated via a modified sagittal occlusion analysis (SO analysis). RESULTS: The mean degree of overjet correction was 5.2 mm (95% CI = 4.8-5.6 mm) and was on average achieved by means of 1.7 mm skeletal and 3.5 mm dental changes. The relationship between the premolars improved by 4.8 mm toward a Class I relationship, facilitated by 1.7 mm skeletal and 3.1 mm dental changes. The 11.3 mm space closure in the maxillary first-molar extraction area resulted from distalization of the second premolars (1.4 mm) and a mesialization of the second molars (9.9 mm). CONCLUSIONS: Overjet correction was essentially achieved by a retrusion of the upper incisors, as well as by ventral growth of the lower jaw and protrusion of the lower incisors. Space closure was only partly achieved by distalization of the premolars.