In the case of the adhesive fixations of the fully ceramic veneers, the light-curing diacrylic cement can be contracted towards the light source during its polymerizations. The scope of this work is to observe the differences in veneers adhesion, as well as the difference of all structures (i.e., dental surface, cement, and internal surface of the veneers) depending by the photopolymerization direction. The study is performed in vitro on five extracted teeth and held in formalin 10%. Each tooth is split in two, in the oral-vestibule direction. On each tooth section, a lithium disilicat veneer is fixed. Half of the tooth is photopolymerized during veneer fixing, perpendicular from the veneer direction, and the other half of the same tooth is photopolymerized from the direction of the tooth, by its structure. Using OCT, in both cases, the space between the tooth and the veneer is measured, and the difference of structure in the mass of the cement is followed. Due to the contraction towards the light source, there are significant differences in the structure of the cement mass, its particles being more concentrated in the direction of light-curing. The results are interpreted based on the perfomed OCT analysis. The adhesion of a veneer is better if the photopolymerization is made from the direction of the tooth, through its structure, practically pulling the cement particles, by its contraction towards the dental structure.
An important challenge in today’s dentistry is to create sturdy and aesthetic restorations. Dental research aims to create restorations with long-term durability and optical properties similar to healthy natural teeth. Recent works have shown that the magnetic handling of a dental adhesive doped with magnetic nanoparticles (MNPs) improves the adhesion between the composite and the dentin. This study presents the preparation of dental adhesives loaded with iron oxide (Fe3O4) NPs incorporated in SiO2 shells, and their applications in the creation of dental veneers. Extracted incisors were prepared for veneering and divided in two groups: Group A was bonded with normal adhesive and Group B was bonded with the augmented adhesive, in the presence of a permanent magnet. The samples were analyzed using stereomicroscopy, optical coherence tomography (OCT), and scanning electron microscopy (SEM), the latter combined with energy dispersive analysis of X-rays (EDAX). All techniques enabled the visualization of the veneer-adhesive and adhesive-dentin interfaces: (i) stereomicroscopy demonstrated that the adhesive layer was thinner for Group B and revealed conglomerates of MNPs in the adhesive layer; (ii) OCT enabled a visualization of the marginal closure, as well as of defects in the two interfaces; (iii) SEM provided a high-resolution image of the adhesive layer, whereas EDAX furnished an elemental analysis of the augmented adhesive. In conclusion, under the action of an external magnetic field, MNPs can penetrate deeper into the demineralized structure of the tooth, reducing the thickness of the adhesive layer and, thereby, decreasing the probability of microleakage.
The formation of dental biofilm follows specific mechanisms of initial colonization on the surface, microcolony
formation, development of organized three dimensional community structures, and detachment from the surface.
The structure of the plaque biofilm might restrict the penetration of antimicrobial agents, while bacteria on a surface
grow slowly and display a novel phenotype; the consequence of the latter is a reduced sensitivity to inhibitors. The
aim of this study was to evaluate with different optoelectronic methods the morphological characteristics of the
dental biofilm.
The study was performed on samples from 25 patients aged between 18 and 35 years. The methods used in this
study were Spectral Domain Optical Coherence Tomography (SD-OCT) working at 870 nm for in vivo evaluations
and Scanning Electron Microscopy (SEM) for validations. For each patient a sample of dental biofilm was obtained
directly from the vestibular surface of the teeth's.
SD-OCT produced C- and B-scans that were used to generate three dimensional (3D) reconstructions of the sample.
The results were compared with SEM evaluations. The biofilm network was dramatically destroyed after the
professional dental cleaning.
OCT noninvasive methods can act as a valuable tool for the 3D characterization of dental biofilms.
Holography is a well-developed method with a large range of applications, including dentistry. This study uses holographic methods for the study of total dental prosthesis. The issue is that the transformation of wax denture base in polymethylacrylate causes dimensional alterations and retractions in the final dental constructs. These could cause the failure of the stability of the complete denture in the oral cavity. Thus, the aim of this study is to determine and to compare using holography, total prosthesis obtained using three different manufacturing methods: pressing, injection, and polymerization. Each of the three types of dentures thus produced were recorded over the previously wax complete base holographic plates. The dimensional alterations that appear after using the different activation methods were thus determined. The most significant modification was remarked in the custom press technology, while the smallest variations were detected in the injection alternative.
KEYWORDS: Optical coherence tomography, Teeth, Composites, FDA class I medical device development, Adhesives, Diagnostics, Interfaces, Composite resins, 3D scanning, Scanners
In clinical dental practice it is often difficult or even impossible to distinguish and control interfacial adhesive defects from adhesive restorations using visual inspection or other traditional diagnostic methods. Nonetheless, non-invasive biomedical imaging methods like Optical Coherence Tomography (OCT) may provide a better view in this diagnostic outline. The aim of this study is to explore evaluations of the marginal adaptation of class I resin composites restorations using Time Domain (TD) OCT. Posterior human teeth have been chosen for this study. The teeth were stored in 0.9% physiological saline solution prior to use. A classical round-shaped class I cavity was prepared and cavities were restored with Charisma Diamond composite by Heraeus Kulzer and using a system of etch and rinse boding. The specimens were subjected to water storage and then to thermo-cycling. Three dimensional (3-D) scans of the restoration were obtained using a TD-OCT system centered at a 1300 nm wavelength. Open marginal adaptation at the interfaces and gaps inside the composite resins materials were identified using the proposed method. In conclusion, OCT has numerous advantages which justify its use for in vitro, as well as for in vivo studies. It can therefore be considered for non-invasive and fast detection of gaps at the restoration interface.
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