Florin Baciu

A Three-Dimensional Finite Element Analysis of Restored Deciduous Canine

The literature reports that dental cavities are an international public health challenge and treatment of decays especially for young children is a medical problem of great importance. Early childhood caries progress rapidly and can cause functional, physical and dentofacial aesthetic impairment. Recent studies show that caries lesions can compromise children’s quality of life due to the pain and discomfort which could lead to disfigurement, acute and chronic infections and to alteration of meals and sleeping habits. Tooth decay occurs when acids in the mouth dissolve the outer layers of the tooth, stripping the tooth of important minerals. Because dental decay often goes untreated, the cavity grows and more tooth structure is lost. Restorative dentistry has the main purpose of rehabilitating the function and aesthetic of tooth. The structural integrity of the restored teeth depends on the state of stress in their different regions due to occlusal loads. The aim of this study performed with the finite element method is to evaluate the stress and strain distributions in bone structure-primary canine-restorative material assembly when a load of 120N is applied all over the upper surface of the model. Particular attention was given to an accurate computer reconstruction of the canine. Therefore with the aid of a CT scanner the tomography images obtained were processed with a special software (Mimics). Two dental restorative materials, commonly used in practice were chosen for the analysis and the results acquired are compared. Also the contact pressure at the interface bone-deciduous canine and deciduous canine-dental material is evaluated in both cases.

Finite Element Analysis of Mechanical Behavior of Restored Maxillary and Mandibular Deciduous Incisors

The management of traumatic dental caries in primary teeth has the main objective to avoid their consequences that can affect the immediate and longterm quality of life of the child. Aggressive forms of decays can develop on smooth surfaces of teeth and progress rapidly, the effect being detrimental on the dentition. The objective of this study was to compare the stress and displacement distributions in the models of two assemblies by means of the three-dimensional finite element analysis: deciduous maxillary lateral incisor - restorative filling – bone structure and deciduous mandibular lateral incisor – restorative filling – bone structure respectively. Both models were subjected to a 120 N static load applied on the upper surface. The models were built from computed-tomography scans. Two different restorative dental materials were considered. In addition, the results obtained were compared with previous research of the authors, i.e. the mechanical behavior of a deciduous restored molar and deciduous restored canine respectively. As a result of the study, it can be concluded that the biomechanical analysis of deciduous dental caries is a valuable aid in enabling the dentist to make correct and effective treatment decisions.

Behaviour of Epoxy Silica Nanocomposites Under Static and Creep Loading

Abstract Specific manufacturing technologies were applied for the fabrication of epoxy-based nanocomposites with silica nanoparticles. For dispersing the fillers in the epoxy resin special equipment such as a shear mixer and a high energy sonicator with temperature control were used. Both functionalized and unfunctionalized silica nanoparticles were added in three epoxy resins. The considered filling fraction was in most cases 0.1, 0.3 and 0.5 wt%.. The obtained nanocomposites were subjected to monotonic uniaxial and creep loading at room temperature. The static mechanical properties were not significantly improved regardless the filler percentage and type of epoxy resin. Under creep loading, by increasing the stress level, the nanocomposite with 0.1 wt% silica creeps less than all other materials. Also the creep rate is reduced by adding silica nanofillers.

Stainless Steel Brackets: In Vitro Corrosion Behaviour and Mechanical Debonding Test

The purpose of the study was to investigate the microchemical, morphological, mechanical and anticorrosive characteristics of the metallic brackets by using energy-dispersive X-ray spectroscopy (EDS), scanning electron microscopy (SEM), electrochemical and shear tests. The changes resulted from the exposure of the metallic brackets to artificial saliva and debonding forces were investigated under orthodontic appliances. The results have shown that metallic brackets studied in this paper present a good design, great electrochemical behaviour in artificial saliva for different pH values (2, 5 and 7), and also great mechanical properties. In the case of shear stress the obtained values were higher than the clinical accepted value. The metallic brackets studied in this paper present a good behaviour in artificial saliva, and good mechanical characteristics. The ARI investigation revealed that most of the adhesive was left on the bracket.

TiSiN coatings for improved bond strength of CoCr alloy to dental ceramic

In this work, TiSiN coatings were selected to improve the adhesion between dental ceramic and CoCr substrate. The coatings were prepared by the cathodic arc technique in N2 reactive atmosphere, at different bias voltages, and analyzed for elemental composition, surface roughness, wettability and corrosion resistance in Fusayama Meyer artificial saliva. After the coating deposition, low-fusing dental ceramic film was fired on coated alloy, using a dental furnace. The bond strength of these specimens was tested using a 3-point bending test.