Force to Debond Brackets from High-fusing and Low-fusing Porcelain Systems

The purpose of this study was to test the hypothesis that porcelain surface finishing, ie, low- and high-fusing porcelain, has an effect on the amount of force required to debond orthodontic brackets. A total of 20 high-fusing and 20 low-fusing porcelain specimens were prepared, polished, and bonded with standard edgewise brackets using a suggested porcelain bonding protocol. The brackets were debonded with a universal testing machine at shear mode. Resin removal was performed using two methods: a multifluted carbide bur with and without the use of Sof-Lex polishing discs. Representative specimens were studied under a scanning electron microscope before and after debonding to assess the surface morphology and potential surface damage. Statistical analysis with a t-test revealed that there was no difference between the two porcelain treatments on the force to debond values and no qualitative differences were observed on the porcelain surface between the two resin clean-up methods. From a clinical perspective, the practitioner can bond ceramic restorations without previous knowledge of the porcelain type used

Craniofacial growth and SITAR growth curve analysis

BACKGROUND: SITAR (SuperImposition by Translation And Rotation) is a shape invariant growth curve model that effectively summarizes somatic growth in puberty. AIM: To apply the SITAR model to longitudinal mandibular growth data to clarify its suitability to facial growth analysis. SUBJECTS AND METHODS: 2D-cephalometric data on two mandibular measurements (AP: articulare–pogonion; CP: condylion–pogonion) were selected from the Denver Growth Study, consisting of longitudinal records (age range: 7.9–19.0 years) of females (sample size N: 21; number of radiographs n: 154) and males (N: 18; n: 137). The SITAR mixed effects model estimated, for each measurement and gender separately, a mean growth curve versus chronological age, along with mean age at peak velocity (APV) and peak velocity (PV), plus subject-specific random effects for PV and mean size. The models were also fitted versus Greulich–Pyle bone age. RESULTS: In males, mean APV occurred at 14.6 years (AP) and 14.4 years (CP), with mean PV 3.1 mm/year (AP) and 3.3 mm/year (CP). In females, APV occurred at 11.6 years (AP and CP), with mean PV 2.3 mm/year (AP) and 2.4 mm/year (CP). The models explained 95–96 per cent of the cross-sectional variance for males and 92–93 per cent for females. The random effects demonstrated standard deviations (SDs) in size of 5.6 mm for males and 3.9 mm for females, and SDs for PV between 0.3 and 0.5 mm/year. The bone age results were similar. CONCLUSION: The SITAR model is a useful tool to analyse epidemiological craniofacial growth based on cephalometric data and provides an array of information on pubertal mandibular growth and its variance in a concise manner

Preliminary Rovibrational Analysis of the nν6+ν1−nν6 Vibration in HCN⋅⋅⋅HF

A preliminary rotation‐vibration analysis of the n=0 and n=1 subbands associated with the nν6+ν1−nν6 hydrogen‐bonded vibration in HCN⋅⋅⋅HF has been completed. The following excited staterotational constantsB′ and band origin frequencies ν0 have been determined for the complex. The results are consistent with a rotation‐vibration interaction constant α1=−68.3±1 MHz which correlates with an excited stater(N⋅⋅⋅F) internuclear distance of 2.762 Å, a decrease of 0.034 Å relative to the ground state.Excited state lifetimes associated with assigned transitions are demonstrated to be ≥1.8×10− 1 0s while the x 1 6 anharmonic constant is evaluated to be 4.01±0.03 cm− 1

"Water, Water, Every Where": Nuances for a Water Industry Critical Infrastructure Specification Exemplar

The water infrastructure is critical to human life, but little attention has been paid to the nuances of the water industry. Without such attention, evaluating security innovation in this domain without compromising the productivity goals when delivering water services is difficult. This paper proposes four nuances that need to be incorporated into a representative specification exemplar for the water industry; these provided input to the exemplar based on a fictional water company

The Erasmus programme for postgraduate education in orthodontics in Europe: an update of the guidelines

In 1989, the ERASMUS Bureau of the European Cultural Foundation of the Commission of the European Communities funded the development of a new 3-year curriculum for postgraduate education in orthodontics. The new curriculum was created by directors for orthodontic education representing 15 European countries. The curriculum entitled ‘Three years Postgraduate Programme in Orthodontics: the Final Report of the Erasmus Project' was published 1992. In 2012, the ‘Network of Erasmus Based European Orthodontic Programmes' developed and approved an updated version of the guidelines. The core programme consists of eight sections: general biological and medical subjects; basic orthodontic subjects; general orthodontic subjects; orthodontic techniques; interdisciplinary subjects; management of health and safety; practice management, administration, and ethics; extramural educational activities. The programme goals and objectives are described and the competencies to be reached are outlined. These guidelines may serve as a baseline for programme development and quality assessment for postgraduate programme directors, national associations, and governmental bodies and could assist future residents when selecting a postgraduate programm

Error-dependent modulation of speech-induced auditory suppression for pitch-shifted voice feedback

<p>Abstract</p> <p>Background</p> <p>The motor-driven predictions about expected sensory feedback (efference copies) have been proposed to play an important role in recognition of sensory consequences of self-produced motor actions. In the auditory system, this effect was suggested to result in suppression of sensory neural responses to self-produced voices that are predicted by the efference copies during vocal production in comparison with passive listening to the playback of the identical self-vocalizations. In the present study, event-related potentials (ERPs) were recorded in response to upward pitch shift stimuli (PSS) with five different magnitudes (0, +50, +100, +200 and +400 cents) at voice onset during active vocal production and passive listening to the playback.</p> <p>Results</p> <p>Results indicated that the suppression of the N1 component during vocal production was largest for unaltered voice feedback (PSS: 0 cents), became smaller as the magnitude of PSS increased to 200 cents, and was almost completely eliminated in response to 400 cents stimuli.</p> <p>Conclusions</p> <p>Findings of the present study suggest that the brain utilizes the motor predictions (efference copies) to determine the source of incoming stimuli and maximally suppresses the auditory responses to unaltered feedback of self-vocalizations. The reduction of suppression for 50, 100 and 200 cents and its elimination for 400 cents pitch-shifted voice auditory feedback support the idea that motor-driven suppression of voice feedback leads to distinctly different sensory neural processing of self vs. non-self vocalizations. This characteristic may enable the audio-vocal system to more effectively detect and correct for unexpected errors in the feedback of self-produced voice pitch compared with externally-generated sounds.</p

Attention wins over sensory attenuation in a sound detection task

'Sensory attenuation', i.e., reduced neural responses to self-induced compared to externally generated stimuli, is a well-established phenomenon. However, very few studies directly compared sensory attenuation with attention effect, which leads to increased neural responses. In this study, we brought sensory attenuation and attention together in a behavioural auditory detection task, where both effects were quantitatively measured and compared. The classic auditory attention effect of facilitating detection performance was replicated. When attention and sensory attenuation were both present, attentional facilitation decreased but remained significant. The results are discussed in the light of current theories of sensory attenuation

Characterisation and microleakage of a new hydrophilic fissure sealant – UltraSeal XT® hydro™

Objectives: The new hydrophilic fissure sealant, UltraSeal XT® hydro™ (Ultradent Products, USA), was characterised and its in vitro resistance to microleakage after placement on conventionally acid etched and sequentially lased and acid etched molars was investigated. Materials and Methods: The sealant was characterised by Fourier transform infra-red spectroscopy, (FTIR), scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX) and Vickers indentation test. Occlusal surfaces of extracted human molars were either conventionally acid etched (n = 10), or sequentially acid etched and laser irradiated (n = 10). UltraSeal XT® hydro™ was applied to both groups of teeth which were then subjected to 2500 thermocycles between 5 and 55 °C prior to microleakage assessment by fuchsin dye penetration. Results: UltraSeal XT® hydro™ is an acrylate-based sealant which achieved a degree of conversion of 50.6 ± 2.2% and a Vickers microhardness of 24.2 ± 1.5 under standard light curing (1000 mWcm-2 for 20 s). Fluoride ion release was negligible within a 14-day period. SEM and EDX analyses indicated that the sealant comprises irregular sub-micron and nano-sized silicon-, barium- and aluminium-bearing filler phases embedded within a ductile matrix. Laser preconditioning was found to significantly reduce microleakage (Mann-Whitney U test, p < 0.001). The lased teeth presented enhanced surface roughness on a 50 to 100 μm scale which caused the segregation and concentration of the filler particles at the enamel-sealant interface. Conclusion: Laser preconditioning significantly decreased microleakage and increased enamel surface roughness which caused zoning of the filler particles at the enamel-sealant interface

The impact of Er:YAG laser enamel conditioning on the microleakage of a new hydrophilic sealant — UltraSeal XT® hydro™

UltraSeal XT® hydro™ is a new hydrophilic, light-cured, methacrylate-based pit and fissure sealant which has been developed by Ultradent Products, USA. The sealant is highly filled with a 53 wt.% mixture of inorganic particles which confer both thixotropy and radiopacity. The principal purpose of this study was to investigate the microleakage of UltraSeal XT® hydro™ as a function of different enamel etching techniques. The occlusal surfaces of sound, extracted human molars were either acid etched, Er:YAG laser irradiated or successively laser irradiated and acid etched. UltraSeal XT® hydro™ was applied to each group of teeth (n=10) which were subjected to a thermocycling process consisting of 2500 cycles between 5 and 50°C with a dwell time of 30s. Microleakage assessments were then carried out using 0.5 % fuchsin dye and optical microscopy. The microleakage score data were analysed using the Kruskal-Wallis, Mann–Whitney U test with Bonferroni adjustment. No significant differences in microleakage were noted between the individually acid etched and laser-irradiated groups (p>0.05); however, teeth treated with a combination of laser irradiation and acid etching demonstrated significantly lower microleakage scores (p<0.001). Electron microscopy with energy-dispersive X-ray analysis revealed that the mineral filler component of UltraSeal XT® hydro™ essentially comprises micrometre-sized particles of inorganic silicon-, aluminium- and barium-bearing phases. Laser etching increases the roughness of the enamel surface which causes a concentrated zoning of the filler particles at the enamel-sealant interface

Fluctuación físico-química, costo ambiental y predicción ecotoxicológica mediante programa computacional Gecotoxic® en la laguna de oxidación Yaurilla, Ica-Perú

El tratamiento inadecuado y sus posibles efectos sociales es una de las preocupaciones ambientales. El propósito del estudio fue evaluar las fluctuaciones de parámetros físicoquímicos, costo ambiental y predicción ecotoxicológica mediante programa computacional Gecotoxic® en la laguna de oxidación de Yaurilla, Ica-Perú. Mediante un muestreo probabilístico aleatorio se midió el pH, sólidos totales, conductividad eléctrica y la temperatura del efluente en mayo, junio, julio y diciembre de 2019. Con los parámetros se estimó el costo ambiental sostenible relativo (COASOR) mediante un cociente entre el costo de evaluación (COA) y el costo de prevención normativo (CONP). Los valores hallados se introdujeron al descriptor análisis residual del programa computacional Gecotoxic® para su predicción ecotoxicológica. El rango de variación para los parámetros fue: pH = 6,01–8,01; sólidos totales = 451–818,9 mg.L-1; conductividad eléctrica = 921–1737,5 uS/cm y la temperatura = 25,75– 25,65°C. La estimación promedio del COASOR fue de recurso sostenible relativo y Gecotoxic® indicó, predicción ecotoxicológica de tipo bajo (30%). Se concluyó que, a pesar de las fluctuaciones entre los valores de los parámetros físico-químicos, el efluente mostró valor de uso como recurso, además, no representó ningún tipo riesgo. No obstante, se recomienda analizarse otros parámetros incluyendo los microbiológicos para la correcta toma de decisiones