Materials and Technologies in Dentistry: Defects, Processing and Characterization

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Authors: Cristina Savencu, Liliana Porojan, Mihaela Bîrdeanu, Adrian Boloș, Sorin Porojan, Aurora Antoniac, Sebastian Gradinaru
Abstract: Technological developments in the field of based metal alloys have led to the implementation of novel manufacturing processes in dental practice. The aim of the study was to evaluate surface characteristics of Co–Cr dental alloys fabricated via conventional casting, computerized milling, selective laser sintering and selective laser melting. The morphology and the topography of the samples were investigated by SEM / EDAX (Model INSPECT S) and AFM (Model Nanosurf® EasyScan 2 Advanced Research). Depending on the nature and chemical composition of the samples the morphology is different. The microstructure of Co–Cr dental alloys depends on the manufacturing technique. Given to the differences in microstructural properties among the tested specimens, further differences in their technological achievement and clinical behavior can be anticipated.
Authors: Sanda Mihaela Popescu, Horia Octavian Manolea, Oana Andreea Diaconu, Veronica Mercuţ, Monica Scrieciu, Ionela Teodora Dascălu, Mihaela Jana Ţuculină, Florian Obădan, Florin Dan Popescu
Abstract: Zirconia is a metal used in dental implantology. Its biocompatibility was studied in vitro and in vivo, results of the studies being analyzed in reviews and meta analyses. The aim of this systematic review was to evaluate biocompatibility of zirconia in animal studies in vivo expressed as results of histomorphometric tests. Databases were searched from 1980 until February 2016, with different combination of the following MeSH terms: zirconium, biocompatibility, dental implants, in vivo, animal studies. Letters to the editors, case reports, commentaries, review articles and articles published in other languages then English were excluded. The search of PubMed, ScienceDirect and Google Scholar databases yielded 690 titles. After abstract screening and duplicate discarding 50 articles were identified and finally, 40 were included in the review. Most of the studies compared zirconia with titanium, a well established material for dental implants. In majority of the studies zirconia showed a similar osseointegration with titanium. Surface implant treatments, like sandblasted and etched zirconia (ZrO2-SLA), alumina toughed zirconia (ATZ), and powder injection molding (PIM) were used to improve osseointegration of zirconia with good results. In the light of histomorphometric test, zirconia, no matter physical and structural forms tested, is a biocompatible material.
Authors: Alexandru Andrei Iliescu, Gabriel Tulus, Paula Perlea, Irina Maria Gheorghiu, Mihaela Georgiana Iliescu, Horia Octavian Manolea
Abstract: Currently bioceramics are preferentially used in various endodontic treatments such as pulp capping, pulp amputation, apexification, root-end fillings, perforation repair, and pulp regeneration. Additionally, bioceramics started to replace traditional materials still used in root canal fillings. The promising clinical results achieved during last 20 years by mineral trioxide aggregate (MTA) promoted in root canal treatments other MTA-like innovative endodontic materials, some of them produced by nanotechnology. Though the newcomers claim to have at least the same efficacy as MTA only rigorous long-term clinical studies might confirm the expectations. Probably the most spectacular effect of using bioceramics in endodontics is mirrored in regenerative treatments. However, are still required proper treatment protocols able to optimize the signaling environment of bioactive molecules for achieving the most efficient pulp regeneration. Pivotal is also the balance between clinical and histological outcomes. As compared to conventional materials used in endodontic treatments bioceramic cements are not only biocompatible but also bioactive as they proved to be involved in controlling the tissue healing and pulp regeneration. MTA or MTA-like cements are already the material of choice in regenerative endodontics, conservative vital pulp therapy and periradicular surgery due to their clinical success rate that spectacularly upraised in recent years. Based on in progress technology of fabrication it is expected that the newcomers belonging to bioceramic cements will overcome some potential clinical and histological downsides. MTA-based endodontic sealers are also promising promoters of improved interfacial bond between the filling material and the dentinal walls of root canal as a guarantee against microinfiltration.
Authors: Cena Dimova, Biljana Evrosimovska, Mirjana Popovska
Abstract: The aim of this paper is to highlight the classification and indications of different bone grafting materials and barrier membrane for everyday clinical practice of contemporary work in the field of oral surgery and periodontology. Number of different growth factors are used together with graft materials. Among these are platelet rich plasma (PRP) and platelet-rich fibrin (PRF). With the simplified technique, an autologous fibrin matrix, which contains platelets and leucocyte growth factors, is acquired.
Authors: Monica Laura Dascalu (Rusu), Codruta Sarosi, Marioara Moldovan, Mândra Eugenia Badea
Abstract: Photodynamic therapy (PDT) also known as Phototherapy or Photo chemotherapy involves the use of a photoactive dye (photosensitive) which is activated by exposure to light of a certain wavelength in the presence of oxygen. Dentists have to deal regularly with oral infections which untreated may cause systemic infections. Oral infections such as caries, periodontal infections and infections of the oral mucosa are available lighting so photodynamic therapy is particularly suitable for oral diseases [1,2]. Antimicrobial chemical treatment is nowadays widely used in the prophylaxis and treatment of inflammation-induced plaque with the risk of resistance development. The use of photodynamic therapy as a therapeutic approach can eliminate this risk, however. Studies in the literature show that both Gram-positive bacteria and Gram-negative bacteria are susceptible to the treatment. Among the advantages of using this method is counted rapid elimination of bacteria, minimal chances of developing bacterial resistance and safety in terms of host tissue and existing normal microflora in the oral cavity [3]. Antimicrobial photodynamic therapy (aPDT) by photochemical reaction uses light at a specific wavelength to activate a nontoxic photosensitizer (PS) in the presence of oxygen to produce cytotoxic products. There are different PSs used in dentistry including methylene blue (MB), toluidine blue O (TBO), indocyanine green (ICG) and curcumin [4].
Authors: Horia Octavian Manolea, Florian Obădan, Sanda Mihaela Popescu, Radu Rîcă, Petre Mărășescu, Alexandru Andrei Iliescu, Constantin Dăguci, Sebastian Gradinaru
Abstract: The lack of a periodontium for a dental implant may lead to high stress concentration at the bone level when the implants are prosthetically loaded. The present paper discusses the current possibilities of implant supported prosthesis making in order to mitigate the impact of occlusal forces. The cement layer may serve as an absorber for the strain, but its role is reduced and poses the risk of excess cement retained in the peri-implant tissue. The use of resin materials for the implant supported prosthetic restorations veneering it has been suggested for many years, but their role it is important in the case of full-arch fixed implant-supported prosthesis with cantilever distal extensions and less in single implant restorations. Nowadays, new materials like fiber-reinforced composites and high-performance polymers as PEEK may be used for the framework of the implant supported prosthetic restorations, but also for the implant or the prosthetic abutment realization.
Authors: Alexandru Andrei Iliescu, Cristian Marian Petcu, Răzvan Mercuţ, Mihaela Georgiana Iliescu, Ileana Cristiana Petcu, Irina Maria Gheorghiu, Tiberiu Ţârcă, Paula Perlea
Abstract: Bone Heating during Osteotomy for Dental Implant Placement is a High Risk Factor of Osteonecrosis. the Aim of this Study was to Investigate in Vitro the Temperature Changes Induced in Bone by Different Burs with External Cooling during the Surgical Step of Osteotomy. it was Used the Digital Infrared Camera FLIR SC640 (Flir Systems) that Allowed a Real-Time Infrared Thermographic Analysis of Thermal Images, Recorded 0.50 m Away from Osteotomy Site. there were Prepared 10 Osteotomy Sites with each MIS System Burs of Progressive Diameter (2 Mm ø, 2.8 Mm ø, and 3.2 Mm ø), at 2000 Rpm, on 30 Samples of Bovine Femoral Bone. the Thermographic Analysis Showed that the Mean Temperature Generated in Bone by Performing the Osteotomy was 46,5oC ± 0,48 for 2 Mm ø Bur, 59,5oC ± 1,62 for 2.8 Mm ø Bur, and 51,4oC ± 0,51 for 3.2 Mm ø Bur. Surprisingly the Maximal Temperatures were Recorded with Intermediatte 2.82 Mm ø Bur. the Infrared Thermography Proved to Be a High Accurate, Fast, and Efficient Non-Invasive Method of Bone Temperature Measurement Generated during Drilling for Placement of Dental Implants. while Drilling the Bone in a Progressive Sequence of Bur Diameters, the Temperature Raise is Non-Uniform because the Quantity of Removed Bone is Changing from One Bur to the other, and the Mechanical Friction of Following Burs in the Series is Reduced as Compared to the Pilot Bur.
Authors: Mihaela Jana Ţuculină, Sanda Mihaela Popescu, Marilena Bătăiosu, Constantin Dăguci, Cristian Marian Petcu, Horia Octavian Manolea, Ionela Teodora Dascălu, Oana Andreea Diaconu
Abstract: The aim of this study is to highlight the morphology of the second maxillary molars root canals and to draw a comparison between the data obtained with and without magnifying means. The study covered a total of 31 extracted human second maxillary molars. After being examined by a thorough physical exam and an X-ray examination, teeth were trepanned in the place of election. Thereby the access cavity was performed using: a) for the stage of pulp chamber ceiling penetration, a globular diamond bur for the turbine, b) for the stage of broadening access cavity, a cylindrical bur inactive in the head for the opposite-angle piece and c ) a Batt bur for the flaring and finishing stage.Afterwards, the sighting of the main root canals was performed using the endodontic probe or Miller file. Examination and sighting of the additional canals was made under magnification using the dental microscope. The molars with three canals had the highest prevalence of endodontic morphology of two upper molars (90.32%). But there were special cases with two channels morphology (6.45%) and four channels morphology (3.22%). After examining the endodontic space under the microscope, there have been identified and secondary canals, approximately 32.25% of molars examined presenting one or more secondary canals. The anatomy of the most frequent upper second molar was three roots with three root canals; the most common variation in morphology is the presence of an mesiobuccal additional canal (MB2). However, we can encounter an unusual number of canals. The importance of magnification, of the dental microscope in our study cannot be ignored because using only the latter we could highlight the real endodontic morphology of the two upper molars extracted examined, finding additional canals in 32.25% of the molars undergoing examination.
Authors: Liliana Porojan, Sorin Porojan, Lucian Rusu, Adrian Boloș, Cristina Savencu, Aurora Antoniac, Sebastian Gradinaru
Abstract: Due to the lower opacity and translucency of many core materials, bilayered ceramic crowns were introduced to obtain sufficient veneer support and to improve aesthetics. Interfaces can have significant influence on the mechanical performance of layered structures. Veneer chipping and zirconia frameworks fractures are critical issues in all-ceramic restorations. The objective of this study was to assess failure analysis of bilayered all-ceramic molar crowns, evidenced by different type of fractures. Experiments were conducted on a right first maxillary molar. Bilayered all-ceramic crowns were obtained with a 0.5 mm thick zirconia milled framework and veneered with hot-pressed ceramics. The specimens were tested at compressive load until failure. The typical macroscopic crack pattern of all samples showed that crack propagation resulted in more broken pieces with sharp edges. Ceramic materials show considerable variation in strength due to their extreme sensitivity to cracks. Understanding the fracture behavior of dental ceramics and its relation to different materials and restorations is important from a clinical point of view.

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