Tooth fracture by impact is the most common cause of fracture in human incisors. We have designed an experimental system to measure the dynamic fracture force of teeth in vitro, and initial results obtained from a sample of healthy, recently removed human incisors are reported. The method was reproducible and reliable, and the results provide a baseline for studies evaluating the effect of endodontic procedures on the dynamic fracture force of teeth.

In this work we studied some of the main effects of the maxillary protraction orthopedic device. The initial dento-craniofacial reactions induced by maxillary protraction similar to that commonly employed in clinical practice are reported. The fringe counting holographic interferometry technique is used to measure displacements. The experiments were performed on a dried human skull; traction application points were situated over the permanent lateral incisors or over the first permanent molars. The results fundamentally reveal an anterior rotation of the dentomaxillary complex, more intense when traction is applied to the lateral incisors, as shown by a more marked extrusion of the molars in this case. Moreover, major deformation patterns could be observed in inner hard structures of the skull base when applying orthopaedic forces.

A non-invasive method is proposed to determine human skin roughness. The technique is based on measurement of the correlation between two field distributions scattered by a metallised triafol (cellulose acetate foil) replica of the epidermal area to be analysed. The two speckle patterns are produced from the same rough surface illuminated by two coherent plane waves (He-Ne laser) under two slightly different angles. The accuracy of the method is highlighted by measurements made on a set of standard samples with roughnesses previously determined by mechanical profilometry. Analysis of the results indicates a precision of around 10%, and an applicability within the interest range of very rough surfaces in excess of 4-5 microns.

No abstract

No abstract