IntroductionA reliable adhesion between fixed devices and dental surfaces is a key factor for the clinical success of any orthodontic treatment. Adhesion preparation is associated with damages related to abrasive cleaning, enamel structure defacing caused by etching, enamel loss when removing resin remnants at orthodontic treatment finishing stage or when conditioning surface for adhesive failure and fractures at bracket removal.AimThe objective of this study was to compare the shear bond strength of metallic brackets to enamel adhered with a novel non-damaging and remineralizing material for enamel versus the traditional 37% phosphoric acid etching.Material and methods75 Premolars collected from 15- to 40-years old healthy donors requiring extraction were collected. The teeth were then randomly divided into three groups (n = 25). One group was used for the experimental new method (EX), the second for the conventional phosphoric acid etching (PA) method and the third group was left without any treatment (NT). The metallic brackets were fixed with Transbond® XT adhesive and composite resin polymerized for 40 s with a halogen photocuring lamp. The shear bond strength was quantified by means of a universal testing machine at 1 mm/min crosshead speed and a load cell of 1 kN.Statistical analysis usedTests of normality, adjustment of the data to a root square, a one-way ANOVA and Tukey tests were performed.ResultsStatistically significant differences between the NT (1.4 MPa), PA (32.1 MPa) and EX (9.7 MPa) groups were observed.ConclusionsThe experimental material for conditioning human enamel induces calcium phosphates crystals on the enamel surface and improves the bond strength in comparison to the NT group.

There is a plethora of routes to produce hydroxyapatite(HA) and in general calcium phosphates(CP) but production usually leads to a mixture of several phases. Besides ionic contamination, most of these methods are cumbersome, restricted to small volumes of product and require a lot of thermal energy. The acid-base route eliminates foreign ions or additives and its only byproduct is water. Heterogeneous reaction drawback is that solid reactants do not easily come in contact with each other and therefore addition and stirring times become very lengthy and still the product is a mixture.The synthesis started from calcium hydroxide and phosphoric acid (PA). Ball milling was used to favor kinetics and stoichiometry. Six sets of PA addition, paddle stirring and ball milling times were used. Products were evaluated by X ray diffraction (XRD), Fourier Transform Infrared (FTIR), scanning electron microscopy (SEM), X ray fluorescence (XRF) and Ca/P ratio. Chemical analysis for calcium proceeded through oxalate precipitate and phosphorus by the phosphomolibdate technique. A set of conditions yielding high purity HA was established.

Todos los medios de almacenamiento usados para ensayos de investigación alteran las propiedades físicas y/o químicas de los dientes, especialmente el color dental.  El objetivo es establecer cual el medio de almacenamiento más indicado para dientes que van a ser usados en estudios de color basados en una revisión sistematizada, y proponer un protocolo específico. Mediante las palabras clave ¨storage, medium¨, ¨teeth¨, ¨color¨, ¨stability¨,  ¨saliva¨, ¨formalin¨, ¨thymol¨, ¨ethanol¨conectadas por AND o OR y consultando las bases de datos PubMed, ScienceDirect, Embase, Scopus, Scielo, Lilacs y Google Scholar, se seleccionaron artículos con nueve criterios de evaluación a tres niveles de evidencia (alto, medio y bajo). Se realizó el análisis, síntesis de la literatura y como producto se establecieron los parámetros para el protocolo de almacenamiento. El resultado final arrojó 8 artículos, dos con nivel de evidencia alto para la saliva natural y/o saliva artificial sin carboximetilcelulosa.  Tres con nivel de evidencia medio para el timol 0,1%, cloramina T 0,5%, glutaraldehido 2% y formalina 10%.  Tres con nivel de evidencia bajo para el etanol, óxido de etileno o hidróxido de potasio. El medio de almacenamiento más indicado es saliva humana seguida por saliva sintética sin carboximetilcelulosa y se estableció con estos parámetros el protocolo del almacenamiento.

Titanium surface was chemically modified with sodium hydroxide, sodium silicate and calcium hydroxide with the purpose of improving metal prosthesis to bone adhesion. Results indicate that Ti modified plates immersed in Hanks solution exhibit increased calcium adsorption in comparison to untreated titanium. Calcium silicotitanate, β-tricalcium phosphate and apatites were detected on the coating.