These studies employed XPS, AFM, Auger spectroscopy and SEM-EDS to characterize the surface properties of alloys and single-crystal alumina and polycrystalline ceramics materials.

The major differences between surface and bulk structures arise from the direct accessibility of surface molecules for reaction with adjacent phases, and the tendency for surface energy minimization to reach en equilibrium state, as mediated by the rearrangement of chemical groups, additive migration, and spontaneous adsorption of low-energy layers from the environment. The near-surface region plays a significant role, since it is involved in corrosion, biodegradation, controlled release and cell contact guidance phenomena.

The results of this work provided the basis for the explanation of effects observed to occur during service of these materials and led to the modification of the synthesis and manufacturing process of materials to meet clinical objectives.

In orthodontics, bonding to enamel has been found to induce structural, color and compositional surface alterations on the host tissue. Microscopic, colorimetric and interfacial compositional studies have elucidated the phenomena associated with etching and bonding.

A set of papers focused on the interfacial properties of the enamel-adhesive-bracket interface under different loading conditions, enamel preparations and wetting conditions.

A number of studies examined the forces and moments developed during wire ligation with conventional and self-ligating brackets and force relaxation of polymeric elastics, employing custom-made configurations.

These papers revealed that the direction of movement and number of teeth engaged in the arch, significantly affect the force applied to teeth with various wire-bracket combinations.

These studies dealt with the mechanical and physical properties of used biomaterials, using basically FT-IR, environmental SEM-EDS and mechanical testing (microhardness) to characterize the materials after service. The integument formed onto biomaterial surfaces after exposure to biological fluids was also described for the first time in the orthodontic and broader dental materials literature. The ageing pattern reported was instrumental in demonstrating the irrelevance of most in vitro ageing protocols, which fail to simulate the intraoral environmental milieu.

These investigations were fundamental in establishing the difference between a material and a material application, where the mode of application and the hosting environment potentially induce changes, which cannot be taken into account in conventional industrial testing. The influential role of those findings resulted in a shift of the interest of investigations establishing a trend in the literature to study the materials in realistic conditions.