Pink Resin as an Alternative for Restoration of Cervical Lesions Associated with Gingival Recession: a Case Report

Gingival recession occurs when the gingival margin is located apically to the cementoenamel junction, causing root exposure. This work aims to report a clinical case of restorative treatment of multiple non-carious cervical lesions (NCCL´s) with gingival-colored resin, as an alternative approach of restorative procedure in cervical defects associated with gingival recession in the aesthetic area. A patient attended a Clinical-School complaining several NCCL´s in addition to Miller's class I gingival vestibular recession in the elements: 13, 21, 22 and 23. Dentin hypersensitivity was absent, however, aesthetic appearance bothered the patient. Presence of occlusal interferences, acid feeding and inadequate brushing habits were observed as important etiological factors for NCCL´s and gingival recessions. Periodontal surgery would be the treatment of choice, however, the patient needed orthodontic intervention first to promote dental alignment and correct distribution of the occlusal load. In order to decrease the progression of the lesions during the orthodontic treatment the NCCL´s associated with gingival recession were restored with gingival-colored resin. Two colors of pink composite resin (color G3 and G5) were incrementally inserted, promoting a correct emergence profile, taking the resin to the lower cavity limit avoiding aggression to the periodontal tissue. Clinical follow-up of 22 months was favorable due to the appearance of restorations and satisfactory periodontal health. Gingival resin can be assigned to improve the aesthetic effect of the restoration at a low cost and time-saving. Keywords: Gingival Recession. Tooth Wear. Composite Resins. ResumoA recessão gengival ocorre quando a margem gengival está localizada apicalmente à junção cemento-esmalte, causando exposição radicular. Este trabalho tem como objetivo relatar um caso clínico de tratamento restaurador de múltiplas lesões cervicais não cariosas (LCNC´s) com resina de cor gengival, como uma forma alternativa de procedimento restaurador em defeitos cervicais associados a recessão gengival em área estética. Uma paciente buscou atendimento odontológico em um centro especializado por apresentar várias lesões do tipo LCNC, além de recessão gengival vestibular classe I de Miller nos elementos: 13, 21, 22 e 23 que não apresentavam sensibilidade, porém eram lesões que a incomodava quanto ao fator estético. Foram observados importantes fatores etiológicos para as LCNC’s e recessões gengivais, como a oclusão desarmônica, alimentação ácida e hábitos de escovação inadequados. A cirurgia periodontal seria o tratamento de primeira escolha, contudo havia a necessidade de intervenção ortodôntica primeiramente para promover alinhamento dentário e correta distribuição das forças oclusais. Com o intuito de diminuir a progressão das lesões durante o tratamento ortodôntico optou-se por restaurar as LCNC´s associadas à recessão gengival com resina composta caracterizada para gengiva. Foram utilizadas 2 cores de resina rosa (G3 e G5) de forma incremental, até o limite inferior da cavidade, promovendo um correto perfil de emergência e evitando agressão aos tecidos periodontais. Acompanhamento clínico de 22 meses mostrou um aspecto favorável das restaurações assim como boa saúde periodontal. Dessa forma, a resina do tipo gengival pode ser indicada para melhorar o efeito estético da restauração a um baixo custo e rapidez no procedimento. Palavras-chave: Retração Gengival. Desgaste dos Dentes. Resinas Compostas.

An Additively Manufactured Sample Holder to Measure the Controlled Release of Vancomycin from Collagen Laminates

The controlled release of antibiotics prevents the spread of pathogens and thereby improves healing processes in regenerative medicine. However, high concentrations may interfere with healing processes. It is therefore advantageous to use biodegradable materials for a controlled release. In particular, multilayer materials enable differential release at different surfaces. For this purpose, collagen sheets of different properties can be bonded by photochemical crosslinking. Here, we present the development and application of an easily accessible, additively manufactured sample holder to study the controlled release of vancomycin from modularly assembled collagen laminates in two directions. As proof-of-concept, we show that laminates of collagen sheets covalently linked by rose bengal and green light crosslinking (RGX) can be tightly inserted into the device without leakage from the upper to lower cavity. We used this sample holder to detect the release of vancomycin from symmetrically and asymmetrically loaded two-layer and three-layer collagen laminates into the upper and lower cavity of the sample holder. We show that these collagen laminates are characterized by a collagen type-dependent vancomycin release, enabling the control of antibiotic release profiles as well as the direction of antibiotic release.

Experimental Measurement of Oil Droplets Size and Velocity Above the Rotor/Stator in a Rotary Compressor

Hundreds of millions of Air conditioning (AC) systems are produced each year. Many of them, especially small AC appliances, use rotary compressors as the system’s heat pump due to their simple structure and high efficiency in a small system. Lubricant oil is used in the rotary compressor to lubricate the moving parts, such as the crankshaft and the rolling piston, and to seal the clearance between the sliding parts, e.g., the clearance between the rolling piston and the cylinder, and the vane and the cylinder. As the compressed refrigerant vapor is discharged from the cylinder through the discharge port, part of lubricant oil in the cylinder would be carried by the vapor and atomize into small droplets in the lower cavity during the discharge process, which is complicated and highly-coupled. Some of these oil droplets would ultimately be exhausted from the compressor and enter other parts in the system, reducing the compressor reliability and deteriorating the heat transfer of the condenser and the evaporator in the system. Our previous research studied the atomization of the lubricant oil during the discharge process in the compressor’s lower cavity. However, the oil droplets’ behavior downstream of the lower cavity is unknown. Thus, studying the oil droplets’ behavior after passing through the rotor/stator can help understand how the rotor/stator would affect the droplet size distribution and movement, thus controlling the flow rate of escaped oil droplets. In this study, a hot gas bypass test rig is built to run a modified rotary compressor with sapphire windows right above the rotor/stator. The oil droplets’ size distribution and movement along the radial direction are obtained at the shaft’s rotating frequency of 30 and 60 Hz by shadowgraph. It is found that droplet size at 30 and 60 Hz varies little in the inner region of the rotor/stator clearance and would increase sharply above the clearance and keep increasing in the outer region of the clearance. More importantly, droplet velocity has a downward velocity component at the inner region and an upward velocity component at the outer region of the rotor/stator clearance. With the result of droplet size distribution and droplet velocity above the rotor/stator, we propose the model of the oil droplet’s path above the rotor/stator, which can be understood as the coupling of a swirling jet and a rotating disk.

Research on Pressure-Retaining Performance of Transfer Device for Abyssal Sediments

In order to retain the activity of microorganisms from abyssal sediment samples, this paper proposes the first device that can be used for the pressure-retaining transfer of seabed sediment samples. The device can transfer sediment from the sampler to the sample processing container and maintain the in-situ pressure of the sample, with the maximum pressure up to 100 MPa. The sample is stirred in the lower cavity of the transfer container and divided into the culture container by pressure difference control. In order to maintain the internal pressure of the device, a pressure stabilization system was designed, and a self-designed conical seal and right-angle combined seal were proposed. The high-pressure test is carried out through the experimental platform, the pressure is maintained for 1.5 h, and the pressure is actively reduced to verify the stability of the pressure stabilization system. The experimental results show that the pressure-retaining performance of the device can meet the transfer of 10,000 m of seabed sediment samples.

Characterization of Oil Droplets in the Lower Cavity of a Rotary Compressor

The rotary compressor is widely used in small air conditioners, and is the most important element in the system. It relies on eccentric rolling pistons that rotate at high speed to compress refrigerant in the cylinder. The lubricant oil in the rotary compressor is used for lubricating the bearing and sealing the clearance of sliding parts. However, the oil can experience complex and highly-coupled atomization processes when discharged from the cylinder, and part of oil droplets can exhaust from the rotary compressor by the refrigerant flow and reduce the efficiency and reliability of the compressor as a result. Thus, characterizing the behavior of oil droplets in the lower cavity of a rotary compressor where the atomization occurs is a major challenge for manufacturers who rely on CFD tools to predict the multiphase flow. By modifying a rotary compressor, the oil behavior in the lower cavity of a rotary compressor is observed and recorded by shadowgraphy. In the current phase, the number, size, and morphology of oil droplets are analyzed statistically with image processing method, which provides better understanding to the atomization mode in the lower cavity, the velocity of the mist of oil droplets is calculated with Optical Flow Velocimetry. The results can assist designers in improving the CFD analysis of compressors and ultimately reducing the Oil Discharge Rate (ODR).

Gelatine cavity dynamics of high-speed sphere impact

We investigate the impact and penetration of a solid sphere passing through gelatine at various impact speeds up to $143.2~\text{m}~\text{s}^{-1}$. Tests were performed with several concentrations of gelatine. Impacts for low elastic Froude number $\mathit{Fr}_{e}$, a ratio between inertia and gelatine elasticity, resulted in rebound. Higher $\mathit{Fr}_{e}$ values resulted in penetration, forming cavities with prominent surface textures. The overall shape of the cavities resembles those observed in water-entry experiments, yet they appear in a different order with respect to increasing inertia: rebound, quasi-seal, deep-seal, shallow-seal and surface-seal. Remarkably, similar to the $We$–$Bo$ phase diagram in water-entry experiments, the elastic Froude number $\mathit{Fr}_{e}$ and elastic Grashof number $\mathit{Gr}_{e}$ (a ratio between gravity and gelatine elasticity) classify all five different phenomena into distinguishable regimes. We find that $\mathit{Fr}_{e}$ can be a good indicator to describe the cavity length $H$, particularly in the shallow-seal regime. Finally, the evolution of cavity shape, pinch-off depth, and lower cavity radius are investigated for different $\mathit{Fr}_{e}$ values.

Experimental investigations on thermal performance characteristics of a solar cavity receiver

The experimentation is carried out to examine the influence of receiver aperture/opening ratio (receiver’s aperture diameter to the maximum diameter ratio, d/D), glass cover thickness and inclination angle of cavity receiver on its collection efficiency for various flow rates of ordinary water as a working fluid. Experimental tests have been conducted at lower incident energy, i.e., at lower cavity wall temperatures (less than 200 °C). The aperture ratio examined encompasses values as 0.46, 0.6, 0.7, and 0.93 for water flowing at flows of 0.8, 0.65, 0.5, and 0.4 LPM that corresponds to Reynolds numbers (Re) of 1880, 1525, 1175, and 938, respectively. The glazing thicknesses of 6, 4, and 2 mm were provided at an aperture. A modified cavity-type receiver is made inclined at angles 90°, 60°, 45°, and 30° (with 90° as down-facing receiver opening and 30° as close to sideway-facing of receiver opening). The tests have been conducted for cavity surface temperatures ranging from 90° to 180 °C. It is observed that an aperture ratio of 0.6 demonstrates maximum receiver performance for the values of Reynolds number studied, while the receiver performance exhibited reducing trend with reduction in receiver tilting angle from 90° to 30°.

Hydrodynamic Cavitation Downstream a Micropillar Entrained Inside a Microchannel—A Parametric Study

Hydrodynamic cavitation downstream a range of micropillar geometries entrenched in a microchannel were studied experimentally. Pressurized helium gas at the inlet tank and vacuum pressure at the outlet propelled distilled water through the device and trigger cavitation. The entire process from cavitation inception to the development of elongated attached cavity was recorded. Three modes of cavitation inception were observed and key parameters of cavitation processes, such as cavity length and angle of attachment, were compared among various micropillar geometries. Cavitation downstream of a triangular micropillar was found to have a distinct inception mode with relatively high cavitation inception numbers. After reaching its full elongated form, it prevailed through a larger system pressures and possessed the longest attached cavity. Cavity angle of attachments was predominantly related to the shape of the micropillar. Micropillars with sharp vertex led to lower cavity attachment angles close to the flow separation point, while circular micropillars resulted in higher angles. Twin circular micropillars have a unique cavitation pattern that was affected by vortex shedding. Fast Fourier transformation (FFT) analysis of the cavity image intensity revealed transverse cavity shedding frequencies in various geometries and provided an estimation for vortex shedding frequencies.

Thermal Transport to Sessile Droplets on Superhydrophobic Surfaces With Rib and Cavity Features

This paper reports on measurements of thermal transport to solitary sessile water drops placed on heated superhydrophobic substrates at constant temperature. Data was obtained by heating the surfaces to specified constant temperatures and gently placing a single water droplet of nominally 3 mm diameter on the surface. The droplet was allowed to evaporate completely while two video cameras and one infrared camera imaged it during the evaporation process. The images were post-processed to yield transient geometric and thermal information, including droplet volume, projected droplet-substrate contact area, and droplet temperature. The total evaporation time and Nusselt and Grashof numbers were determined from the measurements. For all scenarios, the substrate temperature was maintained below the saturation temperature of water and was varied from 60 to 100 °C. Three different rib-patterned superhydrophobic substrates were investigated of 0.5, 0.8, and 0.95 cavity fraction, respectively. The rib features ranged in width from 2 to 30 μm and in height from 15 to 20 μm, while the cavities between the ribs ranged in width from 30 to 38 μm. Results were also obtained for a smooth hydrophobic substrate for comparison purposes. Droplet evaporation times increase with substrate cavity fraction and decrease with increasing substrate temperature. Heat transfer rates decrease with increasing substrate cavity fraction and increase with substrate temperature. The Nusselt number generally increases with the Grashof number raised to the 1/4 power, and Nusselt number is larger for lower cavity fraction substrates.