Removal torque of zirconia abutment screws under dry and wet conditions

The aim of this study was to verify whether screw abutment lubrication can generate higher preload values compared to non-lubricated screws, a titanium abutment was screwed onto an implant analog and scanned with the Procera System to generate 20 zirconia abutments. MKIII Brånemark implants were clamped to a precision torque device, and the abutments were distributed in dry and wet groups with 10 specimens each. In the wet groups, the inner threads of the implants were filled with artificial saliva. All abutments were fastened with a Torqtite screw under 32 Ncm. Ten detorque measurements were performed per group pushing the reverse button of the Torque controller soon after screw tightening with values registered. The mean detorque values were calculated and compared by a Student's t test (?=0.05). The wet condition presented significantly higher mean detorque than the dry condition (31.5 ± 1.2 versus 27.5 ± 1.5 Ncm, respectively; p=0.0000024). In conclusion, there was always a loss in the initial torque values when the removal torque was measured under both conditions. The wet condition presented higher mean torque than the dry condition. Better preload values were established in the wet group, suggesting that the abutment screw must be lubricated in saliva to avoid further loosening.

Are torque values of preadjusted brackets precise?

OBJECTIVE: The aim of the present study was to verify the torque precision of metallic brackets with MBT prescription using the canine brackets as the representative sample of six commercial brands. MATERIAL AND METHODS: Twenty maxillary and 20 mandibular canine brackets of one of the following commercial brands were selected: 3M Unitek, Abzil, American Orthodontics, TP Orthodontics, Morelli and Ortho Organizers. The torque angle, established by reference points and lines, was measured by an operator using an optical microscope coupled to a computer. The values were compared to those established by the MBT prescription. RESULTS: The results showed that for the maxillary canine brackets, only the Morelli torque (-3.33º) presented statistically significant difference from the proposed values (-7º). For the mandibular canines, American Orthodontics (-6.34º) and Ortho Organizers (-6.25º) presented statistically significant differences from the standards (-6º). Comparing the brands, Morelli presented statistically significant differences in comparison with all the other brands for maxillary canine brackets. For the mandibular canine brackets, there was no statistically significant difference between the brands. CONCLUSIONS: There are significant variations in torque values of some of the brackets assessed, which would clinically compromise the buccolingual positioning of the tooth at the end of orthodontic treatment.

Relation between implant/abutment vertical misfit and torque loss of abutment screws

This study investigated whether there is a direct correlation between the level of vertical misfit at the abutment/implant interface and torque losses (detorque) in abutment screws. A work model was obtained from a metal matrix with five 3.75 x 9 mm external hex implants with standard platform (4.1 mm). Four frameworks were waxed using UCLA type abutments and one-piece cast in commercially pure titanium. The misfit was analyzed with a comparator microscope after 20 Ncm torque. The highest value of misfit observed per abutment was used. The torque required to loose the screw was evaluated using a digital torque meter. The torque loss values, measured by the torque meter, were assumed as percentage of initial torque (100%) given to abutment screws. Pearson's correlation (α=0.05) between the misfit values (29.08 ± 8.78 µm) and the percentage of detorque (50.71 ± 11.37%) showed no statistically significant correlation (p=0.295). Within the limitations of this study, it may be concluded that great vertical misfits dot not necessarily implies in higher detorque values.

Measurements of jaw movements and TMJ pain intensity in patients treated with GaAlAs laser

The aim of this study was to evaluate the effectiveness of low-level laser therapy (LLLT) on the improvement of the mandibular movements and painful symptoms in individuals with temporomandibular disorders (TMD). Forty patients were randomly divided into two groups (n=20): Group 1 received the effective dose (GaAlAs laser ? 830 nm, 40 mW, 5J/cm2) and Group 2 received the placebo application (0 J/cm2), in continuous mode on the affected condyle lateral pole: superior, anterior, posterior, and posterior-inferior, twice a week during 4 weeks. Four evaluations were performed: E1 (before laser application), E2 (right after the last application), E3 (one week after the last application) and E4 (30 days after the last application). The Kruskal-Wallis test showed significant more improvements (p<0.01) in painful symptoms in the treated group than in the placebo group. A significant improvement in the range of mandibular movements was observed when the results were compared between the groups at E4. Laser application can be a supportive therapy in the treatment of TMD, since it resulted in the immediate decrease of painful symptoms and increased range of mandibular movements in the treated group. The same results were not observed in the placebo group.

Adhesion of an endodontic sealer to dentin and gutta-percha: shear and push-out bond strength measurements and SEM analysis

The use of an adequate method for evaluation of the adhesion of root canal filling materials provides more reliable results to allow comparison of the materials and substantiate their clinical choice. The aims of this study were to compare the shear bond strength (SBS) test and push-out test for evaluation of the adhesion of an epoxy-based endodontic sealer (AH Plus) to dentin and gutta-percha, and to assess the failure modes on the debonded surfaces by means of scanning electron microscopy (SEM). Three groups were established (n=7): in group 1, root cylinders obtained from human canines were embedded in acrylic resin and had their canals prepared and filled with sealer; in group 2, longitudinal sections of dentin cylinders were embedded in resin with the canal surface smoothed and turned upwards; in group 3, gutta-percha cylinders were embedded in resin. Polyethylene tubes filled with sealer were positioned on the polished surface of the specimens (groups 2 and 3). The push-out test (group 1) and the SBS test (groups 2 and 3) were performed in an Instron universal testing machine running at crosshead speed of 1 mm/min. Means (±SD) in MPa were: G1 (8.8±1.13), G2 (5.9±1.05) and G3 (3.8±0.55). Statistical analysis by ANOVA and Student's t-test (a=0.05) revealed statistically significant differences (p<0.01) among the groups. SEM analysis showed a predominance of adhesive and mixed failures of AH Plus sealer. The tested surface affected significantly the results with the sealer reaching higher bond strength to dentin than to gutta-percha with the SBS test. The comparison of the employed methodologies showed that the SBS test produced significantly lower bond strength values than the push-out test, was skilful in determining the adhesion of AH Plus sealer to dentin and gutta-percha, and required specimens that could be easily prepared for SEM, presenting as a viable alternative for further experiments.

Comparison of the fracture torque of different Brazilian mini-implants

This study evaluated fracture torque by torsion, in relation to the length and diameter of orthodontic mini-implants, to demonstrate their viability for clinical and experimental use based on the torque recommended by the manufacturers. The fractures at the moment of insertion, whose incidence in the literature is around 4%, are principally due to excessive force and the inability of the implant to resist rotational forces. Thirty orthodontic mini-implants of three commercial brands available in Brazil (Neodent 1.6 x 9 mm, Dentoflex 1.6 x 9 mm and Kopp 1.6 x 9 mm) were attached to a device made specifically for this research, leaving the mini-implants with sufficient stability. The miniimplants were submitted to torsion torque, using a digital torque wrench, until their breaking point. The values obtained with the test were submitted to analysis of variance and the Tukey test. The mean values of mini-implant ruptures were 26 N.cm for group A (Dentoflex), 25.4 N. cm for group B (Kopp) and 32.8 N.cm for group C (Neodent). From the Tukey test we could observe that the relationships between the means of the Dentoflex and Neodent groups, and between the Kopp and Neodent groups, were significant. Between the Dentoflex and Kopp groups, significance was nonexistent. All the values found in our research for fracture torque were higher than the limits recommended by the manufacturers for clinical use in orthodontics. The highest values were found in the Neodent group.

VUV spectral line emission measurements in the TCABR tokamak

The study of tokamak plasma light emissions in the vacuum ultraviolet (VUV) region is an important subject since many impurity spectral emissions are present in this region. These spectral emissions can be used to determine the plasma ion temperature and density from different species and spatial positions inside plasma according to their temperatures. We have analyzed VUV spectra from 500 Å to 3200 Å wavelength in the TCABR tokamak plasma including higher diffraction order emissions. There have been identified 37 first diffraction order emissions, resulting in 28 second diffraction order, 24 third diffraction order, and 7 fourth diffraction order lines. The emissions are from impurity species such as OII, OIII, OIV, OV, OVI, OVII, CII, CIII, CIV, NIII, NIV, and NV. All the spectra beyond 1900 Å are from higher diffraction order emissions, and possess much better spectral resolution. Each strong and isolated spectral line, as well as its higher diffraction order emissions suitable for plasma diagnostic is identified and discussed. Finally, an example of ion temperature determination using different diffraction order is presented.

Psychophysical measurements of luminance and chromatic spatial and temporal contrast sensitivity in Duchenne muscular dystrophy

In children with Duchenne muscular dystrophy, color vision losses have been related to dystrophin deletions downstream of exon 30, which affect a dystrophin isoform, Dp260, present in the retina. To further evaluate visual function in DMD children, we measured spatial, temporal, and chromatic red-green and blue-yellow contrast sensitivity in two groups of DMD children with gene deletion downstream and upstream of exon 30. Psychophysical spatial contrast sensitivity was measured for low, middle, and high spatial frequencies with achromatic gratings and for low and middle frequencies with red-green and blue-yellow chromatic gratings. Temporal contrast sensitivity was also measured with achromatic stimuli. A reduction in sensitivity at all spatial luminance contrasts was found for the DMD patients with deletion downstream of exon 30. Similar results were found for temporal luminance contrast sensitivity. Red-green chromatic contrast sensitivity was reduced in DMD children with deletion downstream of exon 30, whereas blue-yellow chromatic contrast sensitivity showed no significant differences. We conclude that visual function is impaired in DMD children. Furthermore, we report a genotype-phenotype relationship because the visual impairment occurred in children with deletion downstream but not upstream of exon 30, affecting the retinal isoform of dystrophin Dp260.

Reproducibility, reliability and validity of measurements obtained from Cecile3 digital models

The aim of this study was to determine the reproducibility, reliability and validity of measurements in digital models compared to plaster models. Fifteen pairs of plaster models were obtained from orthodontic patients with permanent dentition before treatment. These were digitized to be evaluated with the program Cécile3 v2.554.2 beta. Two examiners measured three times the mesiodistal width of all the teeth present, intercanine, interpremolar and intermolar distances, overjet and overbite. The plaster models were measured using a digital vernier. The t-Student test for paired samples and interclass correlation coefficient (ICC) were used for statistical analysis. The ICC of the digital models were 0.84 ± 0.15 (intra-examiner) and 0.80 ± 0.19 (inter-examiner). The average mean difference of the digital models was 0.23 ± 0.14 and 0.24 ± 0.11 for each examiner, respectively. When the two types of measurements were compared, the values obtained from the digital models were lower than those obtained from the plaster models (p < 0.05), although the differences were considered clinically insignificant (differences < 0.1 mm). The Cécile digital models are a clinically acceptable alternative for use in Orthodontics.

Relationship Between Eccentric Hip Torque and Lower-Limb Kinematics: Gender Differences

The purposes of this study were to compare lower-limb kinematics between genders, and determine the relationships among eccentric hip abductor and lateral rotator torques and lower-limb kinematics. The movements of the pelvis, femur, and knee were calculated for 16 women and 16 men during the single-leg squat. Eccentric hip abductor and lateral rotator torques were measured using an isokinetic dynamometer. The results showed that women had greater contralateral pelvic depression, femur adduction, and knee abduction than men. The eccentric hip abductor and lateral rotator torques were correlated with coronal plane femur and knee movements in the overall sample. When the genders were analyzed separately, it was observed that women with greater eccentric hip abductor torque exhibited less femur adduction and femur medial rotation, and greater knee adduction excursion. No significant relationship was observed between the isokinetic and kinematic variables in the male group. The differences between the genders help to explain the greater rate of knee disorders observed in women. Moreover, the eccentric hip abduction action seemed to be more important in women to control the lower-limb movements.

Design and characterization of bridged loop-gap resonators for use in electron paramagnetic resonance measurements

This paper revisits the design of L and S band bridged loop-gap resonators (BLGRs) for electron paramagnetic resonance applications. A novel configuration is described and extensively characterized for resonance frequency and quality factor as a function of the geometrical parameters of the device. The obtained experimental results indicate higher values of the quality factor (Q) than previously reported in the literature, and the experimental analysis data should provide useful guidelines for BLGR design.

Vibration-induced extra torque during electrically-evoked contractions of the human calf muscles

Background: High-frequency trains of electrical stimulation applied over the lower limb muscles can generate forces higher than would be expected from a peripheral mechanism (i.e. by direct activation of motor axons). This phenomenon is presumably originated within the central nervous system by synaptic input from Ia afferents to motoneurons and is consistent with the development of plateau potentials. The first objective of this work was to investigate if vibration (sinusoidal or random) applied to the Achilles tendon is also able to generate large magnitude extra torques in the triceps surae muscle group. The second objective was to verify if the extra torques that were found were accompanied by increases in motoneuron excitability. Methods: Subjects (n = 6) were seated on a chair and the right foot was strapped to a pedal attached to a torque meter. The isometric ankle torque was measured in response to different patterns of coupled electrical (20-Hz, rectangular 1-ms pulses) and mechanical stimuli (either 100-Hz sinusoid or gaussian white noise) applied to the triceps surae muscle group. In an additional investigation, M(max) and F-waves were elicited at different times before or after the vibratory stimulation. Results: The vibratory bursts could generate substantial self-sustained extra torques, either with or without the background 20-Hz electrical stimulation applied simultaneously with the vibration. The extra torque generation was accompanied by increased motoneuron excitability, since an increase in the peak-to-peak amplitude of soleus F waves was observed. The delivery of electrical stimulation following the vibration was essential to keep the maintained extra torques and increased F-waves. Conclusions: These results show that vibratory stimuli applied with a background electrical stimulation generate considerable force levels (up to about 50% MVC) due to the spinal recruitment of motoneurons. The association of vibration and electrical stimulation could be beneficial for many therapeutic interventions and vibration-based exercise programs. The command for the vibration-induced extra torques presumably activates spinal motoneurons following the size principle, which is a desirable feature for stimulation paradigms.

Spin alignment measurements of the K*(0)(892) and phi(1020) vector mesons in heavy ion collisions at root S(NN)=200 GeV

We present the first spin alignment measurements for the K*(0)(892) and phi(1020) vector mesons produced at midrapidity with transverse momenta up to 5 GeV/c at root s(NN) = 200 GeV at RHIC. The diagonal spin-density matrix elements with respect to the reaction plane in Au+Au collisions are rho(00) = 0.32 +/- 0.04 (stat) +/- 0.09 (syst) for the K*(0) (0.8 < p(T) < 5.0 GeV/c) and rho(00) = 0.34 +/- 0.02 (stat) +/- 0.03 (syst) for the phi (0.4 < p(T) < 5.0 GeV/c) and are constant with transverse momentum and collision centrality. The data are consistent with the unpolarized expectation of 1/3 and thus no evidence is found for the transfer of the orbital angular momentum of the colliding system to the vector-meson spins. Spin alignments for K(*0) and phi in Au+Au collisions were also measured with respect to the particle's production plane. The phi result, rho(00) = 0.41 +/- 0.02 (stat) +/- 0.04 (syst), is consistent with that in p+p collisions, rho(00) = 0.39 +/- 0.03 (stat) +/- 0.06 (syst), also measured in this work. The measurements thus constrain the possible size of polarization phenomena in the production dynamics of vector mesons.

New measurements of radial velocities in clusters of galaxies-V

As a part of our galaxy-cluster redshift survey, we present a set of 79 new velocities in the 4 clusters Abell 376, Abell 970, Abell 1356, and Abell 2244, obtained at Haute-Provence observatory. This set now completes our previous analyses, especially for the first two clusters. Data on individual galaxies are presented, and we discuss some cluster properties. For A376, we obtained an improved mean redshift (z) over bar = 0.04750 with a velocity dispersion of sigma(V) = 860 km s(-1). For A970, we have (z) over bar = 0.05875 with sigma(V) = 881 km s(-1). We show that the A1356 cluster is not a member of the ""Leo-Virgo"" supercluster at a mean redshift (z) over bar = 0.112 and should be considered just as a foreground group of galaxies at (z) over bar = 0.0689, as well as A1435 at (z) over bar = 0.062. We obtain (z) over bar = 0.09962 for A2244 with sigma(V) = 965 km s(-1). The relative proximity of clusters A2244 and A2245 ((z) over bar = 0.08738, sigma(V) = 992 km s(-1)) suggests that these could be members of a supercluster that would include A2249; however, from X-ray data there is no indication of interaction between A2244 and A2245.

Self-bound models of compact stars and recent mass-radius measurements

The exact composition of a specific class of compact stars, historically referred to as ""neutron stars,'' is still quite unknown. Possibilities ranging from hadronic to quark degrees of freedom, including self-bound versions of the latter, have been proposed. We specifically address the suitability of strange star models (including pairing interactions) in this work, in the light of new measurements available for four compact stars. The analysis shows that these data might be explained by such an exotic equation of state, actually selecting a small window in parameter space, but still new precise measurements and also further theoretical developments are needed to settle the subject.