Torque value accuracy of preadjusted metal brackets for upper and lower incisors.

BACKGROUND: The more accurate the adjustments built into the brackets, the less the need of additional bends in orthodontic archwires during treatment. METHODS: The aim of this study was to investigate the torque value accuracy of Roth prescription brackets from several commercially available brands. A total of 360 upper and lower incisor brackets from six different commercial brands (i.e. 3M Abzil, KiriumLine; Dentsply GAC, Ovation; Morelli, Roth Light; Ormco, Synthesis; Rocky Mountain Orthodontics, Integra; and 3M Unitek, Miniature Twin) were selected and divided into 18 experimental groups (N.=20). RESULTS: The brackets were submitted to SEM examination to acquire clear photomicrographs of all edges. The angles formed by the slot's walls and bracket's base were measured to calculate the torque values. The measured torque values were submitted to Student's t-test or Mann-Whitney test (global α=0.05) for comparing the experimental groups to Roth prescription values, depending on the bracket indication: +12°, +8° or -1°. A tolerance of ±1° (ISO 27020:2010) was considered. Only experimental groups using upper central incisor brackets from Rocky Mountain Orthodontics (P=0.037) and 3M Unitek (P=0.001) were statistically different compared to the Roth prescription ones (+12°). However, all the groups presented great variability (standard deviation) regarding the same brand and indication, showing that there is no accuracy in the fabrication process. CONCLUSIONS: It is evident that the manufacturing methods of orthodontic brackets need to reach higher degrees of precision and homogeneity.

Imidazoles and benzimidazoles as tubulin-modulators for anti-cancer therapy.

Imidazoles and benzimidazoles are privileged heterocyclic bioactive compounds used with success in the clinical practice of innumerous diseases. Although there are many advancements in cancer therapy, microtubules remain as one of the few macromolecular targets validated for planning active anti-cancer compounds, and the design of drugs that modulate microtubule dynamics in unknown sites of tubulin is one of the goals of the medicinal chemistry. The discussion of the role of new and commercially available imidazole and benzimidazole derivatives as tubulin modulators is scattered throughout scientific literature, and indicates that these compounds have a tubulin modulation mechanism different from that of tubulin modulators clinically available, such as paclitaxel, docetaxel, vincristine and vinblastine. In fact, recent literature indicates that these derivatives inhibit microtubule formation binding to the colchicine site, present good pharmacokinetic properties and are capable of overcoming multidrug resistance in many cell lines. The understanding of the mechanisms involved in the imidazoles/benzimidazoles modulation of microtubule dynamics is very important to develop new strategies to overcome the resistance to anti-cancer drugs and to discover new biomarkers and targets for cancer chemotherapy.

Sequential imaging of an impacted mandibular second premolar migrated from angle to condyle.

Extreme distal migration of impacted teeth to the subcondylar area and condyle is very rare. Using an interesting sequence of radiographs showing the path of the tooth in the mandible, we describe the intrabony migration of a mandibular second premolar from angle to condyle in a young woman. Cone-beam computed tomography was used to establish the precise location of the tooth.

Effect of a low-level laser on bone regeneration after rapid maxillary expansion.

INTRODUCTION: In this study, we evaluated the effects of a low-level laser on bone regeneration in rapid maxillary expansion procedures. METHODS: Twenty-seven children, aged 8 to 12 years, took part in the experiment, with a mean age of 10.2 years, divided into 2 groups: the laser group (n = 14), in which rapid maxillary expansion was performed in conjunction with laser use, and the no-laser group (n = 13), with rapid maxillary expansion only. The activation protocol of the expansion screw was 1 full turn on the first day and a half turn daily until achieving overcorrection. The laser type used was a laser diode (TWIN Laser; MMOptics, São Carlos, Brazil), according to the following protocol: 780 nm wavelength, 40 mW power, and 10 J/cm(2) density at 10 points located around the midpalatal suture. The application stages were 1 (days 1-5 of activation), 2 (at screw locking, on 3 consecutive days), 3, 4, and 5 (7, 14, and 21 days after stage 2). Occlusal radiographs of the maxilla were taken with the aid of an aluminum scale ruler as a densitometry reference at different times: T1 (initial), T2 (day of locking), T3 (3-5 days after T2), T4 (30 days after T3), and T5 (60 days after T4). The radiographs were digitized and submitted to imaging software (Image Tool; UTHSCSA, San Antonio, Tex) to measure the optic density of the previously selected areas. To perform the statistical test, analysis of covariance was used, with the time for the evaluated stage as the covariable. In all tests, a significance level of 5% (P <0.05) was adopted. RESULTS: From the evaluation of bone density, the results showed that the laser improved the opening of the midpalatal suture and accelerated the bone regeneration process. CONCLUSIONS: The low-level laser, associated with rapid maxillary expansion, provided efficient opening of the midpalatal suture and influenced the bone regeneration process of the suture, accelerating healing.