After nearly seven decades of development, dental composite restorations continue to show limited clinical service. The triggering point for restoration failure is the degradation of the bond at the tooth–biomaterial interface from chemical, biological, and mechanical sources. Oral biofilms form at the bonded interfaces, producing enzymes and acids that demineralize hard tissues and damage the composite. Removing bacteria from bonded interfaces and remineralizing marginal gaps will increase restorations’ clinical service. To address this need, we propose for the first time the use of piezoelectric nanoparticles of barium titanate (BaTiO3) as a multifunctional bioactive filler in dental resin composites, offering combined antibacterial and (re)­mineralization effects. In this work, we developed and characterized the properties of dental piezoelectric resin composites, including the degree of conversion and mechanical and physical properties, for restorative applications. Moreover, we evaluated the antibacterial and mineralization responses of piezoelectric composites in vitro. We observed a significant reduction in biofilm growth (up to 90%) and the formation of thick and dense layers of calcium phosphate minerals in piezoelectric composites compared to control groups. The antibacterial mechanism was also revealed. Additionally, we developed a unique approach evaluating the bond strength of dentin–adhesive–composite interfaces subjected to simultaneous attacks from bacteria and cyclic mechanical loading operating in synergy. Our innovative bioactive multifunctional composite provides an ideal technology for restorative applications using a single filler with combined long-lasting nonrechargeable antibacterial/remineralization effects.

The results from the patient analyzed showed that fixed support prostheses on three implants are not recommended from a structural point of view because they do not adequately support occlusal loads. Excessive stress in the superstructure and the cortical bone can be expected, which would anticipate the failure of the restoration. Fixed support prostheses on four implants with a cantilever length of 10mm properly resist occlusal loading.

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URIS is a near-infrared (1 -2.5 microns) intermediate resolution spectrograph (R=1000-3000) with added capabilities for multi-slit, imaging, coronography, and polarimetry, built by the TAC to be a common in strument for the WHT (La Palma). Here we report the results of the two commissioning periods. The image quality was checked, obtaining a FWHM ofO".5 in the Ks band over the whole field ofview (4'.2 x 4'.2). Zero points and sky brightness were measured, and very low values were found in the latter. The long slit spectra obtained matched the expected spectral resolution ( 2.6 pixels for a O".65 -wide slit) Flexure tests were carried out with good results. Several science targets were observed, the most note-worthy result being the detection ofthe CIV 154.9 nm line in the most distant qso at z=6.41. ENTRODUCTIONThe study of the spectra of astronomical objects in the Near Infrared (NIR) has enormous scientific potential: by using NIR, the composition of the dust can be established, molecular hydrogen can be studied, and high redshift (z=1) galaxies whose main emission lines ofActive Galatic Nuclei (AGN) (for example, Ha) lie in the NIR region can also be observed. This kind of instrument can therefore be useful in a wide variety of fields1, from studies of the solar system, stellar physics or extragalactic astronomy to cosmology. However, working in this spectral region (1 -2.5 microns) is quite a challenge, posing several problems for the astronomer.Key points to consider when designing a NIR spectrograph include target acquisition and sky subtraction. Target acquisition is difficult due to the impossibility of using an optical slit view with a CCD, since on the one hand differential sky refraction causes the optical and infrared (IR) image to be shifted by several arcseconds (depending on the airmass), and on the other hand some sources are very red and therefore very weak in the optical image. Another factor to take into account is the strong sky emission in the NIR: for example, the sky emission in the Ks band is 13 magnitude per square arcseconds. The other key point is sky subtraction, as this spectral range is dominated by strong atmospheric OH emissin lines. In order to allow for proper sky subtraction, the design should minimize flexures which will shift the spectral lines. As an example, the user requirement of URIS allows maximum flexure of a few microns between the focal plane and the detector in the course of one hour of integration time. Regarding spectral resolution, in order to avoid the atmospheric OH lines, the optimal resolution is between 1000 and 3000.In February 1998 the IAC started the construction of URIS, a near infrared (NIR) spectrograph for the 4.2 m WHT on La Palma. The main goal of the design was to make it as simple as possible to ensure that the project could be completed within a fixed budget and schedule (which was actually achieved in the end), and at the same time achieve