Torsional properties of commercial nickel-titanium wires during activation and deactivation.

This study evaluated torsional moments on activation and deactivation in commercial, nickel-titanium wires that are intended for use in the initial phases of orthodontic treatment. Nine commercial, rectangular nickel-titanium wires (0.017 x 0.025 in) were tested in torsion. One wire was conventional nickel-titanium, and the others were superelastic nickel-titanium wires. The specimens were tested in a torsiometer for rotations between 10 and 40 degrees in activation and deactivation. Wires E27, RF and R had the highest moments during activation and deactivation, without evidence of the plateau typical of the superelastic effect. Plateaus of constant moment were observed for wires C27, C35, E35, MO, NS, and NI. Torsional moments varied among superelastic nickel-titanium wires, even with wires that had the same transition temperature range. Some superelastic wires had torsional moments that were comparable with conventional nickel-titanium wires.

Three-dimensional evaluation of skeletal and dental asymmetries in Class II subdivision malocclusions.

The objective of this study was to determine if any significant differences existed with regard to dental and skeletal asymmetries between subjects with Angle Class II subdivision malocclusions and subjects with normal occlusions. The sample consisted of 30 subjects in each of the 2 groups. Each possessed a full complement of permanent teeth, including first molars. The average age of subjects was 15.76 years in the Class II subdivision group and 22.42 years in the normal occlusion group. Measurements were obtained with the use of submentovertex, posteroanterior, and corrected oblique cephalometric radiographs. In the submentovertex radiographs, symmetry was assessed by measuring the relative differences in the spatial positions of dental and skeletal landmarks between the right and the left sides in both anteroposterior and transverse dimensions. Coordinate systems were used to represent the mandible, cranial floor, and the maxilla. In the posteroanterior radiographs, symmetry was assessed similarly by measuring the relative differences in the spatial positions of dental and skeletal landmarks between the right and the left sides. In the corrected oblique radiographs, symmetry was assessed by measuring the differences in size of dental and skeletal structures between the right and the left sides. Variables were analyzed with multivariate logistic regression analysis. The results demonstrated that the primary contributor to the differences between the 2 groups was the distal positioning of the mandibular first molars on the Class II side in patients whose mandibles showed no unusual skeletal or positional asymmetries. A secondary contributor was the mesial positioning of the maxillary first molars on the Class II side. Furthermore, the posteroanterior radiographic analysis showed that the more frequent distal positioning of the mandibular molars on the Class II side, compared with the mesial positioning of the maxillary molars on that side resulted in mandibular dental midline deviation to the Class II side more frequently than the maxillary dental midline to the opposite side.

Eruption Guidance Appliance effects in the treatment of Class II, Division 1 malocclusions.

The objective of this research was to cephalometrically evaluate the possible effects of the Eruption Guidance Appliance on the craniofacial complex in a sample of 30 patients, over a treatment period of 26 months. The experimental sample consisted of 30 patients (13 females and 17 males), 27 of which presented with a Class II, Division 1 malocclusion and 3 with a Class I malocclusion. The mean initial chronologic age was 9 years; the treatment period lasted 26 months. A control group was used for comparison and consisted of 30 subjects (13 females and 17 males) of similar ages and spanned a similar observation period. Twenty-six subjects of this control group had Class II, Division 1 malocclusions, and 4 had Class I malocclusions. Lateral cephalometric headplates were obtained for the experimental group initially and after 26 months of treatment. The subjects in the control group were randomly selected from a serial growth study sample from the Orthodontic Department at Bauru Dental School, University of São Paulo, for whom cephalometric headplates were obtained annually from 4 to 18 years of age. Comparative statistics were used to assess possible differences between the experimental and control groups during the 26-month period of observation. Results demonstrated statistically significant increases in mandibular growth, degree of mandibular protrusion, lower anterior and total anterior face height, mesial migration of the lower molars, and mandibular posterior dentoalveolar height. There was also lingual tipping and retrusion of the upper incisors, linear protrusion of the lower incisors, improvement in the maxillomandibular relationship and in molar relationship, as well as a significant decrease in the overjet and overbite and an inhibition of the vertical development of the upper incisors. The study demonstrated no significant changes in maxillary growth during the evaluation period. It was concluded from these results that the effects of the Eruption Guidance Appliance during this time period were mostly dentoalveolar, with a smaller, but significant, skeletal effect.

[Root resorption: preliminary considerations and case report]. / Reabsorção radicular: considerações preliminares e apresentação de um caso clínico.

This article presents a review of the literature on the action of 5 (five) possible predisponent agents of root resorption (treatment time, amount of dental movement, amount of force used, individual susceptibility and trauma) during orthodontic treatment and describes a clinical case with pronounced overjet and overbite where, the presence of resorption in one traumatized tooth limited the mechanics to light forces only.