Comparison of cyclic fatigue and torsional resistance in reciprocating single-file systems and continuous rotary instrumentation systems

As compared with continuous rotary systems, reciprocating motion is believed to increase the fatigue resistance of NiTi instruments. We compared the cyclic fatigue and torsional resistance of reciprocating single-file systems and continuous rotary instrumentation systems in simulated root canals. Eighty instruments from the ProTaper Universal, WaveOne, MTwo, and Reciproc systems (n = 20) were submitted to dynamic bending testing in stainless-steel simulated curved canals. Axial displacement of the simulated canals was performed with half of the instruments (n = 10), with back-and-forth movements in a range of 1.5 mm. Time until fracture was recorded, and the number of cycles until instrument fracture was calculated. Cyclic fatigue resistance was greater for reciprocating systems than for rotary systems (P < 0.05). Instruments from the Reciproc and WaveOne systems significantly differed only when axial displacement occurred (P < 0.05). Instruments of the ProTaper Universal and MTwo systems did not significantly differ (P > 0.05). Cyclic fatigue and torsional resistance were greater for reciprocating systems than for continuous rotary systems, irrespective of axial displacement.

Origin and function of short-latency inputs to the neural substrates underlying the acoustic startle reflex

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Instrumentation of dental implants: a literature review

The aim of this study was to review the literature on the systems used to decontaminate the implant's surface. Different instruments have been proposed, but there is no agreement in the literature about which methods would be more efficient with no damage to the implant surface. It was reported the use of plastic, carbon fiber, stainless-steel and titanium curettes and also the use of other systems such as ultrasonic points with different tips, rubber cups and air abrasion. Literature review: In most of the studies, the injury caused on the titanium surface at the time of instrumentation was examined. In others, the cell adhesion on the titanium dental implants following instrumentation of the implant surface was observed. Moreover, to enhance cleaning around implants, ultrasonic systems were recently tested. Conclusion: Metal instruments can lead to major damage to implant surface, therefore, they are not indicated for decontamination of dental implants surfaces. Furthermore, non-metallic instruments, such as plastic curettes, rubber cups, air abrasion and some ultrasonic systems seem to be better choices to remove calculus and plaque of the sub- and supra-gingival peri-implant area. It is noteworthy that more studies evaluating the effects of these systems are required to establish best practices to be used in the treatment of patients with dental implants.

The effect of the angle of instrumentation of the piezoelectric ultrasonic scaler on root surfaces

To evaluate the influence of variations in the working angle of the piezoelectric ultrasonic scaler (PUS) on root surfaces. Material and methods Fifty-five uniradicular bovine teeth were used, of which 25 teeth were used for the analysis of the roughness and root wear, while the remaining 30 teeth were used for the analysis of morphology (MRS) and the attachment of blood components (ABC). The teeth were randomly divided into five groups according to the type of treatment (G1-G5: piezoelectric ultrasonic scaler; G6: manual curette) and to the PUS working angle applied (G1: 0°; G2: 30°; G3: 45°; G4: 60°; G5: 90°). For statistical analysis, the data describing the MRS and ABC were analysed by the Kruskal–Wallis and Dunn's tests, and the data describing the roughness and tooth wear were analysed by anova and Tukey's tests at the significance level of 5%. Results Manual curette (MC) promoted a smoother root surface than the application of the PUS. The PUS used at the angles of 30° and 45° resulted in a high level of ABC that was comparable to that obtained by MC. Additionally, the group in which the PUS was applied at an angle of 45° exhibited less tooth wear than the other groups. Conclusions Changes in the working angle of the PUS influenced the characteristics of root surfaces after instrumentation.

Analysis of acoustic frequency and wave amplitude generated by the Oscillatory Thoracic Thixotropic Device (Diottix(r)) in human chest

Diottix(r) was calibrated at 25 Hz to achieve the frequency indicated in literature as being effective to mobilize the airways secretions. However, the amplitude and frequency of the waves generated by the equipment in different regions of the chest still need to be investigated. The objective of this study was to analyze the frequency and amplitude of waves generated by Diottix(r) in chests of healthy subjects. Diottix(r) was used in the anterior and posterior regions of the chest. The mechanical waves were captured using stethoscopes connected to electret microphones, which were connected to a digital oscilloscope. Frequency and amplitude data were recorded by the stethoscope, positioned in six points in the anterior region and six in the posterior region of the chest, following the positions commonly used in pulmonary auscultation. Signals were recorded and transferred to a computer with software for their analysis. The frequency of waves did not present a significant change (from 24.9 to 26.4 Hz). The wave amplitude in the anterior versus the posterior region in each area of the lung, the upper, middle and lower, had differences. Diottix(r) produces frequencies in the chest according to the calibrated; thus, it can be a complementary resource to bronchial hygiene maneuvers. The amplitudes of waves seem to be affected by other structures like bone parts and heart.

A new species of hylodes (Anura, Hylodidae) and its secretive underwater breeding behavior

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Acoustic radiation force impulse elastography of the spleen in healthy dogs of different ages

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Acoustic radiation force impulse elastography of prostate and testes of healthy dogs: preliminary results

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Acoustic radiation force impulse (ARFI) elastography of the spleen in healthy adult cats - a preliminary study

Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP)

Tool condition monitoring of aluminum oxide grinding wheel in dressing operation using acoustic emission and neural networks

The grinding operation gives workpieces their final finish, minimizing surface roughness through the interaction between the abrasive grains of a tool (grinding wheel) and the workpiece. However, excessive grinding wheel wear due to friction renders the tool unsuitable for further use, thus requiring the dressing operation to remove and/or sharpen the cutting edges of the worn grains to render them reusable. The purpose of this study was to monitor the dressing operation using the acoustic emission (AE) signal and statistics derived from this signal, classifying the grinding wheel as sharp or dull by means of artificial neural networks. An aluminum oxide wheel installed on a surface grinding machine, a signal acquisition system, and a single-point dresser were used in the experiments. Tests were performed varying overlap ratios and dressing depths. The root mean square values and two additional statistics were calculated based on the raw AE data. A multilayer perceptron neural network was used with the Levenberg-Marquardt learning algorithm, whose inputs were the aforementioned statistics. The results indicate that this method was successful in classifying the conditions of the grinding wheel in the dressing process, identifying the tool as "sharp''(with cutting capacity) or "dull''(with loss of cutting capacity), thus reducing the time and cost of the operation and minimizing excessive removal of abrasive material from the grinding wheel.

From acoustic waves to microwaves

We present here some results of our research related to the optoelectronics and photonics and show all the experimental setups used. Starting with a discussion on the importance of the waves, we demonstrate our achievements based on employment of acoustic, optical, and microwaves and their technological use. The results concern the acousto-optic and electro-optic effects. The generalized analysis of the electro-optic effect reveals a new high induced birefringence in lithium niobate. A patented optical fiber microphone is presented, and its applications to the measurements of acoustic wave velocity in gases and in the laser ultrasound non-destructive evaluation system are discussed. Finally, the generation of microwaves by an optical method with substantial cost reduction is presented.

Cleaning capacity promoted by motor-driven or manual instrumentation using ProTaper Universal system: Histological analysis

The aim of this study was to assess the cleaning capacity of the Protaper system using motor-driven or manual instrumentation. Materials and Methods: Ten mandibular molars were randomly separated into 2 groups (n = 5) according to the type of instrumentation performed, as follows: Group 1 - instrumentation with rotary nickel-titanium (Ni-Ti) files using ProTaper Universal System (Dentsply/Maillefer); and, Group 2 - instrumentation with Ni-Ti hand files using ProTaper Universal (Dentsply-Maillefer). Afterwards, the teeth were sectioned transversely and submitted to histotechnical processing to obtain histological sections for microscopic evaluation. The images were analyzed by the Corel Photo-Paint X5 program (Corel Corporation) using an integration grid superimposed on the image. Results: Statistical analysis (U-Mann-Whitney - P < 0.05) demonstrated that G1 presented higher cleaning capacity when compared to G2. Conclusions: The rotary technique presented better cleaning results in the apical third of the root canal system when compared to the manual technique.

Differences in acoustic and perceptual parameters of the voice between elderly and young women at habitual and high intensity

The present study aimed to compare elderly and young female voices in habitual and high intensity. The effect of increased intensity on the acoustic and perceptual parameters was assessed. Sound pressure level, fundamental frequency, jitter, shimmer, and harmonic to noise ratio were obtained at habitual and high intensity voice in a group of 30 elderly women and 30 young women. Perceptual assessment was also performed. Both groups demonstrated an increase in sound pressure level and fundamental frequency from habitual voice to high intensity voice. No differences were found between groups in any acoustic variables on samples recorded with habitual intensity level. No significant differences between groups were found in habitual intensity level for pitch, hoarseness, roughness, and breathiness. Asthenia and instability obtained significant higher values in elderly than young participants, whereas, the elderly demonstrated lower values for perceived tension and loudness than young subjects. Acoustic and perceptual measures do not demonstrate evident differences between elderly and young speakers in habitual intensity level. The parameters analyzed may lack the sensitivity necessary to detect differences in subjects with normal voices. Phonation with high intensity highlights differences between groups, especially in perceptual parameters. Therefore, high intensity should be included to compare elderly and young voice.

Evaluation of the temporal acoustic window for transcranial doppler in a multi-ethnic population in Brazil

The aim of this study was to relate the presence of a temporal acoustic window (TAW) to the variables sex, age and race. This observational study was conducted in patients under etiologic investigation after stroke, sickle-cell anemia and hospitalization in an intensive therapy neurologic unit. TAW presence was confirmed by bilateral assessment by two neurologists via transcranial Doppler (TCD). Multiple logistic regression was performed to explain the presence of the window as a function of sex, age and race. In 20% of the 262 patients evaluated, a TAW was not present. The incidence of TAW presence was greater in men (odds ratio [OR] = 5.4, 95% confidence interval [CI] = 2.5-11.7, p < 0.01); lower with increased age (OR = 0.9, 95% CI = 0.92-0.97, p < 0.01); and lower among those of African and Asian descent (OR = 0.32, 95% CI = 0.14-0.70, p = 0.005). On the basis of the results, more men than women had TAWs, and the decrease in TAWs was associated with increased age and African or Asian descent.

Análise comparativa do uso de ferramentas de metal duro sem revestimento e revestidas com diboreto de titânio na usinagem da madeira

Pós-graduação em Engenharia Mecânica - FEB