European survey on criteria of aesthetics for periodontal evaluation: The ESCAPE study

Objective: The ESCAPE multicentre survey was designed to (a) compare the agreement of three relevant aesthetic scoring systems among different centres, and (b) evaluate the reproducibility of each question of the questionnaires. / Materials and Methods: EFP centres (n = 14) were involved in an e‐survey. Forty‐two participants (28 teachers, 14 postgraduate students) were asked to score the one‐year aesthetic outcomes of photographs using the Before–After Scoring System (BASS), the Pink Esthetic Score (PES) and the Root coverage Esthetic Score (RES). Mean values of kappa statistics performed on each question were provided to resume global agreement of each method. / Results: Between teachers, a difference of kappa ≥ 0.41 (p = .01) was found for BASS (75%) and PES (57%). Similarly, RES (84%) and PES (57%) were different (p < .001). No difference was found between BASS (75%) and RES (84%). No difference was found between students, whatever the scoring system. Questions of each scoring system showed differences in their reproducibility. / Conclusions: The outcomes of this study indicate that BASS and RES scoring systems are reproducible tools to evaluate aesthetic after root coverage therapies between different centres. Among the various variables, lack of scar, degree of root coverage, colour match and gingival margin that follows the CEJ show the best reliability

Preparation of low-density xerogels through additives to TEOS-based alcogels

A new process for preparing silica xerogels with similar textural properties to silica aerogels by drying under vacuum has been studied. The xerogels are produced by adding, before gelation, 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) to tetraethylorthosilicate (TEOS)-based alcogels, synthesised in a single base-catalysed (NH3) step. It is hypothesized that EDAS acts as a nucleation agent leading to silica particles with a hydrolysed EDAS core and a shell principally made of hydrolysed TEOS. The EDAS concentration and the basicity of the aqueous NH3 solution are important parameters influencing the resistance of the gel to drying stress. A decreasing EDAS/TEOS ratio or an increasing concentration of NH3 at constant EDAS content leads to less shrinkage during drying and so the final pore volume is larger. Gels prepared with a low EDAS/TEOS ratio (about 0.03) contain large particles (similar to 20 nm) due to the nucleation process by EDAS, thus the pores between those particles are also large and the drying stress is reduced. (C) 1999 Published by Elsevier Science B.V. All rights reserved

Synthesis by sol-gel process and characterization of barium-titanate

Barium titanate gels are prepared by sol-gel process from titanium isopropoxide and barium hydroxide in presence of methoxyethanol, methanol and water. These gels are dried under vacuum. The influence of the hydrolysis ratio, the temperature and the vacuum level during drying is discussed

Synthesis of barium-titanate by the sol-gel process

Homogeneous BaTiO3 gels were prepared by hydrolysis and polycondensation reactions between titanium isopropoxide and barium hydroxide in the presence of methoxyethanol, methanol and water. Gel formation mechanisms were investigated by Raman scattering spectrometry. Two drying methods are carried out: either in air with a possible formation of barium carbonate or in a vacuum furnace, sheltered from CO2. The influence of the drying method on texture is studied through nitrogen adsorption-desorption isotherm analyses. A heat treatment is deduced from thermogravimetry and differential scanning calorimetry results. The influence of the calcining temperature on the texture and the crystallization of the solids has been measured. For the first time, the transformation at 900 degrees C from the cubic to the tetragonal form of BaTiO3 has been observed by polarization microscopy

Preparation of low-density xerogels by incorporation of additives during synthesis

Low-density xerogels were prepared by incorporation of an additive to alcogels prior to gelation. The additives studied are 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS), 3-aminopropyltrimethoxysilane (AMS), propyltrimethoxysilane (PMS), tetramethylorthosilicate (TMOS) and 3-aminopropyltriethoxysilane (AES) using tetraethylorthosilicate (TEOS) as main silica precursor. Samples were also prepared with EDAS as additive and TMOS as main silica reagent. When the additive contains methoxy groups, it reacts first, forms nuclei on which the main reagent TEOS reacts to form the silica particles. The nucleation mechanism by the additive occurs only in case of a difference of reactivity between additive and main silica precursor. The other group of the additive (amine, alkyl group, ...) influences only the gelation time. In case of ethoxy groups (series AES/TEOS) or methoxy groups (series EDAS/TMOS) for both additive and main reagent, there is no nucleation by the additive. (C) 2001 Elsevier Science B.V. All rights reserved

Textural properties and thermal stability of silica-zirconia aerogels

peer reviewe

Textural properties of low-density xerogels

The extent of shrinkage during drying is controlled by the balance between the capillary pressure developed in the pore liquid and the modulus of the solid network. One first method to obtain low-density xerogels consists in strengthening TEOS-based alcogels by providing new monomers to the alcogel after gelation. In the second method, low-density xerogels are produced by surface modification (silylation) of the wet gel with trimethylchlorosilane. The capillary pressure is reduced and the presence of non-reactive species on the surface makes the shrinkage reversible. A reduction of the capillary pressure can be achieved by introduction of a substituted alkoxide 3-(2-aminoethylamino)propyltrimethoxysilane (EDAS) to a TEOS-based alcogel, synthesised in a single base-catalysed step. This additive acts as a nucleation agent leading to big silica particles (similar to 20 nm) with a low EDAS/TEOS ratio (similar to 0.03). The pores between those particles are also large and the drying stress is reduced. The textural properties of those three materials are compared: bulk densities of the samples modelled on the first and third method are varying in the same range (0.25-0.35 g/cm(3)) while xerogels obtained by the surface modification process are less dense (0.1-0.15 g/cm(3)). The biggest pores are observed in the third method. (C) 2000 Elsevier Science B.V. All rights reserved