Search

Aim of the study: The aim of this study is to evaluate the resistance of different marginal fit geometries for a provissional fixed dental prothesis, which can have an impact on the periodontal health. Materials and methods: Acording to the principles of the tooth preparation, four types of marginal design were made: feather edge, rounded shoulder, chamfer and heavy chamfer. Using a direct technique, prepared teeth were poured into metal abutments, temporary composite resin crowns were made and cemented. All four abutments were analyzed using theoretical and experimental methods. Results: The results obtained from the mechanical tests were more reliable than those obtained from numerical analyses. A chamfer marginal finish line a pre prosthetic periodontal therapy can have greater impact on the soft tissue healing process. Conclusions: These preliminary studies enhance the idea of ​​differentiating preparations for distinctive alternative prosthetic treatment plans.

The serviceable laser technology in medical field has created working protocols in upper labial frenulum surgery. In this article, based on literature research available on PubMed we have reviewed the protocols, advantaged and disadvantages of using different types of lasers by performing upper labial frenectomy.

3D-printing application in dentistry not only enables the manufacture of patient-specific devices and tissue constructs, but also allows mass customization, as well as digital workflow, with predictable lower cost and rapid turnaround times. 4D printing also shows a good impact in dentistry, as it can produce dynamic and adaptable materials, which have proven effective in the oral environment, under its continuously changing thermal and humidity conditions. It is expected to further boost the research into producing a whole tooth, capable to harmoniously integrate with the surrounding periodontium, which represents the ultimate goal of tissue engineering in dentistry. Because of their high versatility associated with the wide variety of available materials, additive manufacturing in dentistry predominantly targets the production of polymeric constructs. The aim of this narrative review is to catch a glimpse of the current state-of-the-art of additive manufacturing in dentistry, and the future perspectives of this modern technology, focusing on the specific polymeric materials.

Aim of the study In the field of digital dentistry, Computer-Aided Design/Computer-Aided Manufacturing (CAD/CAM) systems have changed the fabrication of prosthetic restorations by fulfilling both the aesthetic requirements and mechanical performance. This study aims to highlight, by conducting a chromatic evaluation of zirconium oxide when altering the sintering parameters Materials and methods Four groups of zirconium oxide each group formed by 5 copings were made through milling and Exocad digital design software. The design was completed and the files were processed with the Zeno 4030 M1 milling machine (I-MES Wieland). Following milling, the copings were sintered in HTS MIHM-VOGT furnace at a maximum sintering temperature of 1650°C and heating rates of 30°C/min or a rapid rate of 90°C/min. Controlled cooling prevented rapid temperature decrease, thereby minimizing internal stress. Modifications of time and temperature parameters were applied to groups 2, 3, and 4. Chromatic analysis of the specimens was registered with the Vita Easy Shade spectrophotometer. Results It was found that adjustments in sintering temperature and timing are significantly affecting the chromatic outcomes of the non-metallic zirconium structures. Temperature adjustments facilitate the coalescence of zirconium oxide particles and the formation of a robust structure, with changes in it affecting the optical behaviour of the structure. Deviations from the optimum temperature and sintering timing parameters negatively affect the shade. Conclusions In conclusion, milled and sintered zirconium oxide structures can achieve aesthetic excellence, provided by the sintering protocol when the temperatures and sintering furnaces are accurately calibrated.

Aim of the study This manuscript summarizes important ethical considerations relevant to embryo research. The aim of this study was to assess the opinion of three categories of doctors regarding the ethical and legislative implications of scientific research on human embryos. Material and methods To assess the opinion of doctors about the use of human embryos in research, from a related point of view, a questionnaire with 10 questions was made. Each question has three possible answers. Results The results were analyzed according to the age criterion, as follows:18-25 graduated doctors; 26-45 young doctors; 45-65 adult doctors with experience in the field. Conclusions Following the interpretation of the questionnaires, it can be concluded that, in view of the group of people considered, graduated doctors have more knowledge about the current legislation and ethical measures that accompany scientific studies on human biological material. Also, the third group of doctors with experience in the field tend to show the same knowledge as the first group.

Aim of the study Ethical problems most often arise in research. One of the most important ethical rules governing research on humans is that participants must give their informed consent before taking part in a study. Informed consent is therefore a vital part of the research process, and as such entails more than obtaining a signature on a form. Most researchers however, do not have the requisite knowledge of the importance of informed consent in research. This paper attempts a synopsis of the place of informed consent in research study. Materials and methods A review of literature on informed consent in research. Literature search was done using Google search engine as well as international and local journals. Results Informed consent as an aspect of medical ethics, balances autonomy and beneficence, and provides adequate assurance of voluntary and autonomous participation without negative repercussions on access to study benefits. The search showed that this if adhered to in research, will surely maintain the dignity of man and the integrity of research as a field of human endeavour. Conclusions Researchers must therefore ensure that potential research participants be given sufficient information about a study, in a format they understand, to enable them to exercise their right to make an informed decision whether to participate in a given research.

Aim of the study. In this study, we examined how the choice of fabrication technology impacts the flexural strength of denture bases, considering the potential long-term consequences of permanent stresses on these structures. Such stresses can eventually result in cracking, fracture, or a loss of adaptation within the prosthetic field, which undergoes dynamic changes over time. Material and methods. The flexural strength was tested on specimens made of the same material (based on thermopolymerizable PMMA), using three different technologies: the classic press packing process and traditional polymerization, the injection technology and polymerization under constant pressure and an original suction-injection process (vacuum-pressure alternation), with polymerization under continuous pressure. The actual testing of the flexural strength was carried out in collaboration with the Department of Strength of Materials within the Faculty of Civil Engineering and Architecture Timisoara. Results & Conclusions. Superior outcomes were achieved through the suction-injection method, with polymerization under sustained pressure, in comparison to injection techniques associated with polymerization under constant pressure. These results surpassed those attained through manual press packing procedures and traditional hot polymerization methods.

Aim of the study: To evaluate the efficacy of Optical Coherence Tomography (OCT) in non-invasively monitoring temperature variations during ceramic sintering for dental prosthetics, emphasizing the importance of precise temperature control for optimal material properties and structural integrity. Materials and Methods: The study utilized OCT to examine 17 metal-ceramic restorations at various sintering temperatures (standard, 80°C below, and 50°C above the standard). The method involved generating 61 cross-sectional images per prosthesis to identify defects and structural changes. Results: OCT revealed significant insights into the impact of temperature deviations on ceramic microstructure, including uniform grain sizes at standard temperatures and areas of reduced retention at elevated temperatures, highlighting the technology’s potential in quality control. Conclusions: OCT offers a rapid, accurate, and non-destructive means to assess sintering temperatures and detect defects in dental ceramics, facilitating improvements in dental prosthetics’ fabrication process. The study advocates for OCT’s integration into routine dental laboratory practices to enhance prosthesis quality and reliability.

Aim of the Study: The aim of this study is to investigate the modifications that may occur in case of sintering temperature deviation for metal-ceramic crowns. Materials and Methods: For this in vitro study were made 15 metal-ceramic crowns for tooth 2.1 and were divided into 5 groups. The ceramic veneering comprised different sintering temperatures optimized for different properties: group 1 was sintered at 910 ºC as per the manufacturer’s recommendation, group 2 was sintered at 940ºC (+30 ºC), group 3 was sintered at 960ºC (+50 ºC), group 4 was sintered at 880ºC (-30 ºC), and group 5 was sintered at 860 ºC (-50 ºC). Using the EXOCAD scanner the maxillary cast was scanned to obtain the metal frameworks from Cr-Co alloy (SCHEFTNER CoCr – 30 microns). Ips InLine One ceramic shade A3 developed by Ivoclar Vivadent Inc is applied in two layers, each one sintered at the same temperature. After ceramic sintering, the shade of each group was registered with Vita Easy Shade spectrophotometer and Vitapan Classical shade guide. Results: Errors in sintering temperatures can change the ceramic’s density and mechanical properties but may also lead to colour shifts. This phenomenon occurs due to alterations in the ceramic material’s microstructure, which can impact its optical properties and, consequently, its perceived colour. Conclusions: In conclusion, our study highlights the crucial impact of sintering temperature variations on the quality and integrity of metal-ceramic dental restorations. Our findings point towards the need for further innovation and research in thermal management within dental ceramics processing to achieve restorations that are not only aesthetically pleasing but also functionally reliable and compatible with the natural dentition.

The aim of the study was to assess the mechanical strength of metal frameworks for fixed partial prostheses, made of Co-Cr alloy. Subsequently, the obtained structures were sectioned at the areas of interest and welded using two technological processes: laser and plasma. The mechanical tests were conducted using the Mecmesin MultiTest 5-i device. Following the mechanical tests, it was observed that the control samples did not fracture but yielded through deformation. The samples welded with laser fractured, while those welded with plasma fractured at a much lower value. The success of welding depends on the joint surface, absence of sharp angles, ideal surface preparation, avoidance of inclusions and discontinuities, and avoiding a reduced cross-sectional area. The mechanical strength of welded joints influences the longevity of a repair of the metallic component of a prosthesis. Statistical analyses confirm that repairing metal frameworks for fixed prosthetic restorations using laser represents a viable option, even though the samples fractured under high mechanical loads.

Aim of the study The resistance to functional and parafunctional stresses of devitalized teeth is multifactorial, but the choice of a specific endodontic post system influences the restoration’s longevity. This primary ex-vivo study aims to evaluate the compressive strength of three different non-metallic post systems and to analyze the appearance of fracture surfaces (fractography) using optical microscopy and alongside statistical analysis that validates their behavior. Material and methods For this study, three groups of non-metallic post systems were considered as follows: glass fiber-reinforced photopolymerized resin, pressed ceramic, and pressed ceramic on glass fiber. The sample size has a length of 0.8mm and an average diameter of 0.2mm. Subsequently, the samples were embedded in self-polymerizing resin to be secured in the workspace of the Zwick Roell 5kN testing machine that works at loading speed of 2 mm/min. The fractographic analysis of the obtained surfaces were performed with the Optika SLX3 microscope and C-B16 camera, at magnifications of 20, 50, and 90X. Results The data obtained from the mechanical tests were statistically processed and the results showed significant differences regarding the compressive strength of non-metallic post systems made from different materials and different technologies. Conclusions The group containing posts made from pressed ceramic on glass fiber exhibited higher resistance to applied compressive forces.

Background: Removable prostheses have seen a fundamental change recently because of advances in polymer materials, allowing improved durability and performance. Despite these advancements, notable differences still occur amongst various polymer materials and processing technologies, requiring a thorough grasp of their mechanical, physical, and therapeutic implications. The compressive strength of dentures manufactured using various technologies will be investigated. Methods: Traditional, injection molding, and additive and subtractive CAD/CAM processing techniques, all utilizing Polymethyl methacrylate (PMMA) as the main material, were used to construct complete dentures. The specimens underwent a compressive mechanical test, which reveals the differences in compressive strength. Results: All the specimens broke under the influence of a certain force, rather than yielding through flow, as is characteristic for plastic materials. For each specimen, the maximum force (N) was recorded, as well as the breaking energy. The mean force required to break the dentures for each processing technology is as follows: 4.54 kN for traditional packing-press technique, 17.92 kN for the injection molding technique, 1.51 kN for the additive CAD/CAM dentures, and 5.9 kN for the subtractive CAD/CAM dentures. Conclusions: The best results were obtained in the case of the thermoplastic injection system and the worst results were recorded in the case of 3D printed samples. Another important aspect depicted is the standard deviation for each group, which reveal a relatively unstable property for the thermoplastic injected dentures. Good results here in terms of absolute property and stability of the property can be conferred to CAD/CAM milled group.

Three ceramic and composite computer-aided design/computer-aided manufacturing (CAD/CAM) materials from different manufacturers (Cerasmart (CS)—nanoceramic resin; Straumann Nice (SN)—glass ceramic and Tetric CAD (TC)—composite resin) were tested to investigate the biocompatibility and sustainability on human fibroblasts and keratinocytes cells. Each type of CAD/CAM blocks restorative materials with fine and rough surfaces was exposed to an acidic environment for one month. After that, various powders were obtained by milling. In parallel, powders were also prepared from each restorative material, which were not exposed to the acidic environment. The cytotoxic effects were investigated by means of MTT and LDH assays, as well as nitric oxide production on two human normal cell lines, namely, fibroblasts (BJ) and keratinocytes (HaCaT). In addition, the degree of adhesion of fibroblast cells to each CAD/CAM material was evaluated by scanning electron microscopy (SEM). The results showed that the two samples that were exposed to an acidic environment (CS and SN) induced a reduction of mitochondrial activity and plasma membrane damage as regards the fibroblast cells. A similar effect was observed in TC_fine-exposed material, which seemed to induce necrosis at the tested concentration of 1 mg/mL. No oxidative stress was observed in fibroblasts and keratinocytes treated with the CAD/CAM materials. Regarding the adhesion degree, it was found that the fibroblasts adhere to all the occlusal veneers tested, with the mention that the CS and SN materials have a weaker adhesion with fewer cytoplasmic extensions than TC material. With all of this considered, the CAD/CAM restorative materials tested are biocompatible and represent support for the attachment and dispersion of cells.

The epidemiology of OSCC continues to increase despite the progress that has been made. More than ever, the diagnostic approach process needs to focus on genetic and epigenetic alterations. The aim of our study was to identify and correlate the presence of COL9A1 gene variants in two types of samples from OSCC patients. Methods: Our pilot study included 32 subjects diagnosed with OSCC. Fresh tumour tissue and peripheral blood samples were used in order to identify the genotypes of the COL9A1 gene. Variables, such as age, gender and tobacco and alcohol use, were also taken into consideration. The DNA analysis of the samples was based on a tagged SNP (rs550675) for the allelic discrimination. Results: The statistical significance and correlation of the COL9A1 genotypes within the two categories of samples was statistically significant (p < 0.001) for the C/T and T/T genotypes, providing an important perspective on the potential identification in blood samples of the gene mutation encountered in OSCC. Conclusions: This is the first study that focused on providing preliminary results using blood samples via the identification of COL9A1 gene variants in OSCC patients. The possibility of introducing a liquid biomarker by targeting this genetic variant is an appealing perspective for screening and diagnosis.

The aim of this work is to assess the crystalline structure modification of an SLM Co-Cr-W dental alloy, veneered with two different ceramics, by means of X-ray diffraction (XRD), atomic force microscopy (AFM), and scanning electron microscopy, coupled with energy-dispersive spectroscopy (SEM-EDS). Ten identical plates were fabricated using SLM and were subsequently subjected to ceramic veneering. Following the repeated firing of the ceramic layers, carried out at temperatures exceeding 900 °C, new crystalline phases and variations in the crystallite sizes in the SLM Co-Cr-W dental alloy used for the substructure were detected via XRD. The two veneering ceramics showed significant differences in their behavior, beginning with the first firing, accompanied by structural changes. AFM micrographs and histograms of the surface heights over the whole scanned area of the samples showed that the surface of the Co-Cr-W dental alloy is strongly affected by the repeated firings necessitated by the ceramic firing process, a finding in accordance with the XRD results. The SEM investigation revealed that the different firing parameters had an impact on the alloy, the ceramic microstructure, and the surface quality. The differences in the chemical composition of the ceramics, highlighted by EDS, are reflected in their behavior. The crystalline alloy structure is influenced by the repeated firings of the ceramic layers.

Background and Objectives: The excessive use of smartphones for various tasks led to a new adverse postural phenomenon called text neck. The aim of this study was to investigate the effect of the text neck posture (TNP) on static occlusion by using the T-Scan III occlusal diagnostic system. Materials and Methods: Nineteen subjects (aged 20 to 24 years) were considered for this research. They had normal values for anterior overbite and overjet, Angle Class I occlusion, no posterior crossbite, and no signs or symptoms of cervical or temporo-mandibular disorders. Occlusal registrations were performed with the T-Scan III system in a normal, neutral head posture (NHP), as well as in the TNP. The investigated parameters were: occlusion time (OT), asymmetry index of the occlusal force (AOF), percent of the maximum movie force (%MMF), and the time elapsed from the last occlusal contact until the maximum intercuspation (MAT-OTB). The last three parameters were analyzed in the maximum area frame (MA) of the registrations. For the statistical analysis of the recorded data, the Wilcoxon Signed Ranks test and the Spearman’s correlation coefficient were used. Results: The following values were obtained in NHP and in TNP: for AOF, 14.88 ± 10.39% and 18.04 ± 12.83%, respectively; for OT, 1.34 ± 1.84 s and 1.32 ± 1.8 s, respectively; for the %MMF, 97.5 ± 2.83% and 96.31 ± 3.17%, respectively; for MAT-OTB, 2.08 ± 1.82 s and 1.45 ± 2.3 s, respectively. There were no statistically significant differences between the static occlusal parameters measured in NHP and those in TNP. However, the high values of the AOF and OT in NHP revealed an imbalance of the occlusal force distribution between the right and left side in maximum intercuspation (MI), as well as a lack of simultaneity of static occlusal contacts. Furthermore, there was a significant, direct, and strong correlation between OT and AOF in NHP. Conclusions: The NHP should not be used as the starting position in TNP simulations in T-Scan studies, so as to avoid statistically insignificant differences between static occlusion in NHP and TNP. The healthy standing subjects, with normal occlusal relationships from the clinical point of view, revealed an occlusal instability in NHP when examined with the T-Scan.