The goal study is benchmarking flexural strength FS of compressive strength CS, compression diametrical DTS (diametrically tensile strenght) and Vickers hardness for two nanocomposites experimental AD1 and AD3 achieved within the Research Institute in Chemistry Raluca Ripan Cluj Napoca and for the commercial product of the Kerr Premise company �. Electron microscopy aspects pre- and post-fracturing are also shown to highlight the structure of materials and spread

The purpose of this study was: Structural characterization of two commercial nanocomposite materials (Premise ™/Kerr Corp and Tetric EvoCeram�/ Ivoclar-Vivadent); Evaluation of the marginal adaptation and adhesive interface achieved with two commercial adhesive systems (Optibond SoloPlus ™/Kerr Corp and G-Bond ™/GC). Investigation was done using electronic scanning microscopy (SEM).

Marginal adaptation at composite enamel interface was assessed through direct clinical method, three-dimensional scanning and optical microscopy respectively for three composite materials with Nano filler: Tetric EvoCeram� (Ivoclar Vivadent-), Premise™ (Kerr Corp.) and experimental material C20 (�Raluca Ripan� Chemistry Research Institute, Cluj-Napoca). Clinical evaluation of marginal adaptation highlights at 6 months and at 12 months a rate of 25-40% marginal defects, regardless the Nano composite material used. Characterisation of interface between Nano-composite material and dental tissue requires a complex multifactorial assessment.

In this study an attempt to improve a three unit partial denture design is presented by performing experimental trials to find the failure load of a Y-TZP dental infrastructure. The experimental results are linked with FEA predictions to explain failure and find the optimum design. The test samples used were three unit fixed partial dentures obtained by CAD/CAM using as starting point a clinical case. Design improvement attempt was to increase connector cross-section size and modify its shape. Four samples with circular and elliptical connector cross-sections and 5mm2 and 9mm2 area were tested in flexure. The models created for CAM were used to perform FEA and find the stress distribution, pinpoint the stress concentrators and link the results to experimental failure modes. The results showed that connector design plays an important role in restoration success and increasing connector cross-section area the stress is distributed in a uniform manner. It was concluded that increasing connector cross-section area and using a wider shape (ellipse) strongly decreases failure probability.

Using nanotechnology to produce composite materials it has been possible to obtain materials with similar or better mechanical properties than previous generation of microhybrids, and with exceptional aesthetics and chandelier due to the particularities of nanomaterials. At the same time, the improvement of adhesive techniques to enamel and dentin allowed the expansion of the area of direct composite restorations with a better prognostic over time.Eight carie-free molars were used and each of them was prepared with two class II cavities, which were filled using the C13 and C20 nanocomposites and the A1 and A2 experimental adhesive systems prepared at the Raluca Ripan Chemistry Research Institute. The teeth were divided into four groups of two teeth each, depending on the adhesive system and the composite material used. Scanning electron microscopy images (SEM) have described the adhesive interface and structure characteristics for the two nanocomposite materials and for the two studied adhesive systems.The studied nanocomposites have a variable number of porosities and air bubbles, with a clinical importance which is yet hard to establish.The experimental adhesives used produce a good interface and infiltration of the smear-layer but have not been visualized inside the dentinal canals.In vitro studies are necessary to evaluate the durability of adhesion in the case of self-etch adhesives in one or two steps.