Papers by Keyword: Enamel

Abstract: Subsurface photoacoustic imaging with high resolution is utilized to image the teeth layer due to periodontal tissue inflammation. The aim of this imaging method is to determine the difference between healthy teeth and teeth affected by inflammation based on the acoustic signals obtained. An 808 nm diode laser is used as a radiation source, a condenser microphone is used as a detector, and computer numerical control (CNC) is used for the sample scanning process. The samples were healthy and inflamed Sprague-Dawley rat teeth. The average acoustic intensity of healthy teeth layers was 60.200.9 dB for enamel and 52.210.9 dB for dentin, while the average acoustic intensity of inflammation-affected teeth layers was 93.140.4 dB for enamel and 84.840.4 dB for dentin. Based on the histogram results obtained, the generative adversarial network (GAN) method can be used to improve photoacoustic image resolution to become more detailed. The study shows that high-resolution subsurface photoacoustic imaging can be utilized to image teeth layers.

Abstract: Shallow cracks are often observed in dental enamel, however do not normally lead to deep fractures. Previous work has highlighted the toughening mechanisms that operate in enamel during crack propagation, but very little is known about the deformation and stress fields arising around the propagating cracks during realistic loading conditions. This work aims to elucidate how the stresses are distributed within human dental enamel when a pre-existing crack is subjected to opening and surface contact with in situ indentation. We present a synchrotron-based in situ analysis coupled with a linear elastic finite element method simulation. The experimental reconstructed stress fields identified a prominent residual stress within the enamel, accompanied by a visible pattern that appeared clearly associated with its underlying microstructure. The numerical modelling of the stress field and discerning of surface contact and crack opening caused by the indentation was subsequently possible, even if in this study the influence of the anisotropy induced by the presence of features at a smaller scale was neglected. The implications of these findings and directions for future research are discussed.

Abstract: The goal of this study was to characterize the mechanical behavior of dentin, dental enamel and a nanoparticulate composite resin, used in dental restorations. This characterization was performed through the static and dynamic Vickers hardness test. As for the biological tissue assays, third included human molars were used. The nanoparticulate resinous composite was condensed into a matrix, measuring approximately 10x10x2mm. The obtained HV values were represented by hardness maps. The distribution of hardness values along the enamel and dentin structures occurred unevenly in the two hardness analyzes. For dental enamel, there were differences in hardness values when compared dynamic to static tests. This difference did not occur in dentin. It was observed that the mechanical behavior of the resinous composite resembled more the behavior of the dentin than the enamel.

Abstract: The aim of this in vitro study was to investigate the changes in surface roughness of different nanocomposite restoratives and enamel after application of 1.23% acidulated phosphate fluoride (APF) gel. Twelve specimens were prepared for each composite material and human enamel. The APF gel was applied to the surface of the six specimens of each experimental group for 60 sec every 24 h for 4 days. The other six specimens did not receive APF treatment (control). The surface roughness was measured using a VSI microscope. One-way ANOVA and Tukey’s test were used to compare surface roughness between materials for each experimental group at a level of significance of a=0.05. There were no statistically significant differences in Ra values among the composites which did not receive APF treatment (p>0.05). After APF treatment the lowest surface roughness exhibited enamel (0.18±0.04 Ra) and the highest Dyract Extra (0.62±0.07 Ra) followed by Tetric EvoCeram (0.59±0.06 Ra) and Beautifil II (0.51±0.06 Ra). Filtek Z350 XT presented the lowest Ra values (0.23±0.03). All the experimental groups exhibited higher Ra values after APF treatment (p<0.05), except for Filtek Z350 XT (p>0.05). Application of APF gel on the specimen surfaces influenced the surface roughness of enamel and the tested dental composite restoratives depending on their composition.

Abstract: The project aims to produce quality enamel colors from locally available materials in order to reduce costs. In the course of the research, information is collected on imported enamel colors and a study is carried out on chemical compositions and quality of the colors. At the same time, there is a study on local materials which can potentially be used to produce enamel colors, starting from basic colors such as red, blue and green. The study has found that the imported enamel colors qualify as lead glass because it contains 23-28% of lead. The study has also found that red enamel (transparent) blue enamel (transparent), blue enamel (opaque), green enamel (transparent), and green enamel (opaque) have similar level of density and hardness. Red enamel (opaque) has lower level of density and hardness due to its porosity which can be observed with naked eyes. The COE level is similar for all of the tested colors because their chemical compositions are similar. The study produces quality blue and green enamel at much lower cost. Colors of the enamel are achieved by adding different metal oxide. The color blue (translucent and opaque) is from adding cobalt (Co). Chromium (Cr), manganese (Mn), iron (Fe), cobalt and copper (Cu) together produces translucent dark green, while chromium and copper (without cobalt) produces opaque as lighter green. However, it has not been able to produce red enamel yet but has requested for samples from another research project “Developing New Technology to Produce Jewelry from Synthesized Red Crystal” for further study.Keywords: Enamel; Jewelry; Glass; Local Raw Materials

Abstract: nanosize TiO₂/SiO₂ thin films were deposited by sol-gel dip-coating method on enamel substrates. Crystal structure, micro-structure, hydrophilic property, gloss property was investigated by X-ray diffract meter, scanning electron microscope, CCD camera, enamel gloss meter. The results show that the hydrophilic property of the enamel was greatly increased by heating the enamel with coating TiO₂/SiO₂ film; the gloss property of the enamel surface greatly increased after the enamel coated with TiO₂/SiO₂ film. The main crystals in TiO₂/SiO₂ film on the enamel were anatase when the baking temperature was below the 700°C.

Abstract: The present study was conducted with the aim of evaluating and comparing the microleakage at the dentin and enamel/composite interfaces of two adhesive systems. The adhesives are: a new-developed experimental adhesive systems and OptiBond FL (Kerr Corp.) The new adhesive system was prepared for the composite material as three steps adhesive (etchant, primer and bonding). The bonding resin contains the base monomer that was present in the corresponding composite material, HEMA and TEGDMA as diluents. Twenty box-type Class V standardized cavities were prepared on the facial and oral surfaces of each tooth, with coronal margins in enamel and apical margins in cementum (dentin). The preparations were restored with two restorative materials a new experimental microfilled resin composites based on Bis-GMA analogue and hybrid resin composite Herculite XRV Ultra (Kerr Corp.). The teeth were thermocycled and immersed in 2% methyl blue solution for 24 hours. The specimens were sectioned buccolingually into 3 slices and the resulted sections were examined using a stereomicroscope under 40x magnification. The extent of dye penetration was measured in a quantitative manner. This measurement was converted into percentage using the formula described by Sano et al. I=p/Lx100. These percentage values were submitted to variance analyses (ANOVA) and t test at a p<0.05 level of significance. Scanning electron microscopy was used in order to see the interface between tooth and composite restoration. Significantly less microleakage was associated with the use of OptiBond FL adhesive system at the enamel surface. Between the enamel and the dentin margins no significantly statistical differences were found just for the experimental adhesive system. This adhesive containing water and ethanol as solvent performed significantly better at the dentin margins.

Abstract: Objective: To test and contrastive analysis the crystal structure and mechanical characteristics of enamel and dentin of primary and permanent teeth by XRD and contact angle meter, provide information and experimental data for bionics and designs of dental materials. Methods: Teeth were randomly divided into four groups, including permanent teeth enamel group, permanent teeth dentin group, primary teeth enamel group, and primary teeth primary teeth. The crystal structure and mechanical characteristics of teeth were tested by XRD and contact angle meter. The results were analyzed with one-way ANOVA. Results: The crystalline and grain size of enamel were significantly larger than dentin’s. The crystalline and grain size of enamel and dentin of permanent teeth were also larger than primary teeth. Conclusions: The XRD and contact angle of primary and permanent teeth are closely related to their structures, Dental filling material to give full consideration to their different property.

Abstract: The purpose of this study was to investigate the effect of liquid polishing system (BisCover) on color stability of the bleached enamel upon exposure to a staining agent-red wine. Forty specimens were prepared. They were divided into 2 groups and different procedures, including only bleaching with Opalescence PF (PF) or Opalescence regular (R) gels, and application of BisCover after blaeching (PF-B, R-B) were used. Unbleached specimens were served as control groups (control-1 and control-2). The specimens were stored for 48 h in red wine. The color of all specimens was measured before and after exposure with a spectrophotometer, and total color change (ΔE*) were calculated. The data were analyzed with a one-way ANOVA and the means were compared by Tukeys post hoc analysis (α=0.05). PF-B and R-B groups demonstrated significantly less color change than PF and R groups. the control-1 and control-2 groups had the least color change. No significant difference were observed between PF and R group. BisCover improved the color stability of bleached enamel in red wine.

Abstract: Objective: To investigate the microstructures and mechanical characteristics of enamel and dentin of primary and permanent teeth by AFM, analyze their relationships and provide information for bionics and designs of dental materials. Methods: After embedding, cutting and grinding, 10 primary teeth and 10 permanent teeth were randomly divided into four groups. The morphology of samples was obtained by AFM and the roughness and Young’s modulus were calculated by JPK DP Data processing version 4.0 software. Results: In permanent teeth groups, the enamel rods arrange more tightly than those in primary teeth groups. The roughness of primary enamel （1203±39.5nm）was higher than permanent teeth（954.6±30.5nm）.The Young′s modulus of enamel in primary teeth（80.4±7.7GPa）was lower than permanent teeth（90.8±2.2GPa）. The roughness of dentin in primary teeth （1695±67.6nm）is higher than permanent teeth （1210±45.3nm）and the Young′s modulus of dentin in primary teeth（19.8±1.9 GPa）was lower than the permanent teeth （23.1±1.0 GPa）. Conclusions: The mechanical characteristics of primary and permanent teeth are closely related to their microstructures.