André Weissheimer

Maxillary canine retraction with self-ligating and conventional brackets

OBJECTIVEnTo measure space closure during the retraction of upper permanent canines with self-ligating and conventional brackets.nnnMATERIALS AND METHODSnFifteen patients who required maxillary canine retraction into first premolar extraction sites as part of their orthodontic treatment completed this study. In a random split-mouth design, the retraction of upper canines was performed using an elastomeric chain with 150 g of force. The evaluations were performed in dental casts (T0, initial; T1, 4 weeks; T2, 8 weeks; T3, 12 weeks). The amount of movement and the rotation of the canines as well as anchorage loss of the upper first molars were evaluated.nnnRESULTSnThere was no difference between self-ligating and conventional brackets regarding the distal movement of upper canines and mesial movement of first molars (P > .05). Rotation of the upper canines was minimized with self-ligating brackets (P < .05).nnnCONCLUSIONnDistal movement of the upper canines and anchorage loss of the first molars were similar with both conventional and self-ligating brackets. Rotation of the upper canines during sliding mechanics was minimized with self-ligating brackets.

Mordida cruzada posterior: uma classificação mais didática

The aim of this work is to present a new posterior crossbite classification, being this more didactic and of easy understanding, differing from the others in your nomenclature, preserving, however, the basic principles that govern the Orthodontics. This new classification makes the posterior crossbite diagnosis process systematized and accurate, assisting the clinician in the elaboration of a suitable treatment plan and as consequence, leading to more favorable prognostic of this malocclusion.

In vitro evaluation of force degradation of elastomeric chains used in Orthodontics

OBJECTIVEnTo analyze the in vitro force degradation of four different brands of elastomeric chains: American Orthodontics, Morelli, Ormco and TP Orthodontics.nnnMETHODSnThe sample consisted of 80 gray elastomeric chains that were divided into four groups according to their respective manufacturers. Chain stretching was standardized at 21 mm with initial force release ranging from 300 g to 370 g. The samples were kept in artificial saliva at a constant temperature of 37°C and the degradation force was recorded at the following time intervals: initial, 1, 3, 5, 7 and 9 hours, and 1, 7, 14, 21, 28, and 35 days.nnnRESULTSnThere was a statistically significant difference between the groups regarding the force degradation, mainly within the first day, as a force loss of 50-55% was observed during that time in relation to the initial force. The force delivered at 35 days ranged from 122 g to 148 g.nnnCONCLUSIONSnAll groups showed force degradation over time, regardless of their trademarks, a force loss of 59-69% was observed in the first hour compared to baseline. However, because the variation in force degradation depends on the trademark, studies such as the present one are important for guiding the clinical use of these materials.

A technique of CBCT superimposition in implant dentistry

An abstract is not required.

Immediate effects of rapid maxillary expansion on the nasal cavity using Haas-type and Hyrax-type expanders in CBCT

Purpose: To evaluate and compare the immediate effects of rapid maxillary expansion (RME) on the nasal cavity dimensions in subjects treated with Haas-type and Hyrax-type expanders using cone-beam computed tomography (CBCT). Methods: Thirty-one growing patients (mean age=10.8 years old) with transverse maxillary deficiency were randomly divided into two groups: Haas group (n=16) and Hyrax group (n=15). All patients had RME with initial screw activation of 4 quarter turns followed by activations of 1⁄2 turns per day (0.4mm) until the expansion reached 8mm opening at the screw. CBCT scans were taken before RME (T1) and at the end of the active phase of expansion (T2). Vertical and transverse measurements were performed at different regions of nasal cavity for comparison between groups and treatment times. Intraclass correlation coefficient (ICC), paired Student’s t-test and repeated measures ANOVA (α-level p<0.05) were calculated. Results: RME procedure increased every vertical and lateral nasal cavity dimensions (p<0.001). The most significant gains were observed in the lower portions of the nasal cavity located at the anterior and medial regions. Conclusions: Both appliances were able to create significant changes in the dimensions of the nasal cavity immediately after RME. However, the Hyrax-type expander presented greater transverse effects on the airway. Correspondence to: Luciane Macedo de Menezes, Professor, Department of Orthodontics, Pontifical Catholic University of Rio Grande do Sul (PUCRS), Porto Alegre, Rio Grande do Sul, Brazil, Tel: 55-51 3320.3562; E-mail: luciane. menezes @pucrs.br

Rapid 3D mandibular superimposition for growing patients

OBJECTIVEnTo evaluate the precision and reproducibility of a protocol to perform rapid voxel-based superimposition of the mandible in growing patients using CBCT.nnnMATERIALS AND METHODSnThe sample comprised two cone-beam computed tomography scans taken at least 1 year apart from each of 24 growing patients. Voxel-based superimposition was performed by two examiners independently. The internal part of the symphysis extending to the first molar was used as the reference. The superimposition process took approximately 5 minutes. Once the mandibles were superimposed, surface models were created and root mean square (RMS) changes were obtained by means of iterative closest point. To evaluate precision, differences in three areas were measured between time point 1 (T1) and time point 2 (T2) superimposed. To evaluate reproducibility between different examiners, the distances between T2 superimposed by each operator were measured in five different areas. Descriptive statistics were used to evaluate the precision of the superimposition and the interexaminer reproducibility measurements for each case were reported individually.nnnRESULTSnThe superimposition mean error between T1 and T2 for the right and left sides of the mandible and chin were 0.23 mm, 0.25 mm, and 0.33 mm, respectively. Interexaminer reproducibility error was ≤0.3 mm in 20 of 24 cases for measurements near the registration area. In the ramus area, two cases had errors >1 mm (1 mm-1.3 mm).nnnCONCLUSIONnThe rapid superimposition was precise for assessing dentoalveolar changes and structures close to the registration area. However, evaluation of the condyles and ramus area had limitations and needs improvement.

Midfacial Protraction With Skeletal Anchorage After Pterygomaxillary Separation.

The present article reports the treatment of a 7-year-old girl with maxillary hypoplasia associated with multiple tooth agenesis through maxillary protraction with skeletal anchorage and pterygomaxillary separation. Two titanium mini-plates were placed in the lateral region of the nasal cavity and used as anchorage for maxillary protraction with a reverse-pull facemask. Pterygomaxillary separation was also performed to enhance the effects of maxillary protraction. One week after surgery, 300u200ag of force was applied on each side to protract the maxilla. Active treatment time was 4 months, with 12 additional months of follow-up. Analysis of the cone beam computed tomography images demonstrated that skeletal anchorage enabled the correction of the maxillomandibular discrepancy, with an improvement in facial appearance and occlusion and with no dental effects. Pterygomaxillary separation was not effective, showing no superior orthopedic response on maxillary advancement or restrictions to maxillary growth in the 12-month post-treatment follow-up.