background and aims. the aim of this study was to evaluate the effect of different etching times on enamel color stability after immediate versus delayed exposure to colored artificial saliva (cas). materials and methods. human first premolars were divided into five groups of twenty. a colorimeter was used according to the cie system on the mid-buccal and mid-lingual surfaces to evaluate initia...

INTRODUCTION Optimal pit and fissure sealing is determined by surface preparation techniques and choice of materials. The performance of pit and fissure sealant materials has been intensively investigated, yet no single product is reported as an ideal sealant. In children, moisture control during cavity preparation is always a big challenge, and hence, hydrophilic sealants have been developed. ...

CH3I vapor etching of masked and patterned GaAs substrates has been experimentally investigated. For GaAs samples masked with silicon nitride stripes that are wider than 30 tzm, the etch depth increased compared to unmasked samples, the magnitude of which increased with increasing mask width. Etching of bulk substrates of (l l l)Ga and (lll)As GaAs revealed a dependence of etch rate on crystal ...

OBJECTIVES To determine the influence of different etching times (5, 15 or 30 s) on the morphology and micro-tensile bond strength (muTBS) of primary dentin. METHODS For muTBS study, nine primary molars were randomly distributed in three experimental groups. Three Class I cavities per tooth were drilled and etched (37% orthophosphoric acid gel for 5, 15 or 30 s). Excite adhesive was applied a...

By combining substrate-free structures with anodic bonding technology, we present a simple and efficient micro-electro-mechanical system (MEMS) thermal shear stress sensor. Significantly, the resulting depth of the vacuum cavity of the sensor is determined by the thickness of silicon substrate at which Si is removed by anisotropic wet etching process. Compared with the sensor based on a sacrifi...

We demonstrate an approach for producing an array of nanopores on a silicon surface. The methods used combine nonlithographic pattern transfer and chlorine plasma etching to produce ,60 nm diam holes up to 1 mm in depth. The near-normal specular optical reflectance of these systematically modified surfaces is found to decrease dramatically with pore depth across the entire 2.0–6.0 eV photon ene...