Key Engineering Materials Vol. 587

Abstract: Titanium alloys are widely used in medical applications, due to their good mechanical properties, high corrosion resistance and biocompatibility. The aim of this paper was to investigate the cytotoxicity of novel titanium alloys: Ti21Nb6Zr15Ta, Ti25Nb10Zr8Ta, Ti17Nb5Zr5Al, Ti7Nb7Zr2Al with fibroblast-like cells derived from human osteosarcoma cell line (HOS). The results were compared with that of conventional biomedical alloys, like Ti6Al7Nb and Ti6Al4V. In vitro citotoxicity of titanium alloys was evaluated by fluorescence microscopy and MTT colorimetric assay. The results showed that the materials analyzed had no cytotoxic effects on HOS fibroblast-like cells, permitting their attachment and proliferation. Also the new titanium alloys present a higher cell viability than that of the conventional alloys. As a consequence, the TiNbZrTa and TiNbZrAl alloys can be considered as potential candidates for biomedical applications.

Abstract: The present paper takes into consideration four titanium alloys from the system Ti-Mo, with different molybdenum contents in order to highlight the mechanical and structural behavior of them. The Dynamic Mechanical Analysis was made and this was in correlation with microstructural aspects and surface properties of the experimental alloys. The macrostructural features are the same for all Ti-Mo alloys after bending tests.

Abstract: Bacterial contamination of implanted devices is a common cause of their failure. Microbial contamination of the biomaterials differs from that of natural tissues. In fact, the contamination modalities of medical devices depend on many peculiar factors related to them: the chemistry of the biomaterial, the physical properties of the surface, the design of the medical device, the extension of surgical invasion, and the time of application. The environment and/or the conditions and response of the host also contribute to the development of infection. Viruses, fungi, protozoas and bacteria are all involved in biomaterial contamination. They are endogenous commensals of the mouth, not virulent in planktonic form, but pathogens when arranged in biofilm.In this paper we review the potency of application of Gallium doping to the surface biomaterials addressed for surgical implantation in order to contrast the bacteria biofilm formation

Abstract: Restoring alveolar bone following tooth extraction or pathological diseases is important, and recent efforts have been made to overcome the use of autografts during dental implantation. Although micro-macroporous biphasic calcium phosphate (MBCPTM) has performed well in orthopedic procedures, few studies have investigated its use in dentistry. Here, we report a greater than eight-year clinical follow-up of bone regeneration using MBCPTM after sinus grafting. MBCPTM technology is a unique mixture of hydroxyapatite and β-tricalcium phosphate, which displays both macroporosity and microporosity. A total of 25 patients (33 implantation sites) were evaluated by X-rays, and their pre-operative and immediate post-operative bone heights were measured. After approximately six months, dental implantation was performed. Subsequently, X rays were performed each year, and bone height was measured. In all cases, radio-opacity of the implantation area decreased with time, indicating resorption and bone ingrowth at the expense of the MBCPTM material. After one year, the implantation area had the appearance of physiological bone and <11% of height loss was observed. Strikingly, the newly formed bone was preserved after 78 years of follow-up, with only <14% of height loss recorded. We demonstrate that sinus grafting followed by dental implantation with a resorbable and bioactive synthetic bone graft material (MBCPTM technology) safely and efficiently supports dental implantation.

Abstract: Jaw deformities from tooth removal can be prevented and repaired by a procedure called socket preservation. Socket preservation can greatly improve the smile’s appearance and increase the chances for successful dental implants for years to come. The procedure begins with atraumatic tooth extraction. Every attempt is made to preserve the surrounding bone and soft tissue, with an emphasis on being careful not to fracture the delicate buccal plate. There are a number of techniques and instruments that aid in this process. In general, one never wants to elevate so that force is directed toward the buccal plate. Once the tooth is extracted, all the granulation tissue is removed from the socket. It is important that good bleeding is established in the socket. Next, a bone graft material is placed into the socket.Various materials are used in modern dental and maxillofacial surgery for bone tissue substitution and reconstruction. All osteoplastic materials can be divided into four groups by origin: autogenic, allogenic, xenogenic and synthetic. The development of new medical technologies enables use of achievements in material science, biochemistry, molecular biology and genetic engineering while creating new combined synthetic materials for bone grafting. Mineralized cancellous bone is appropriate for most socket preservation cases.Synthetic resorbable materials were intended as an inexpensive substitute for natural hydroxyapatite. Synthetic graft materials include various types of calcium phosphate ceramics: tribasic calcium phosphate; bioglass; hydroxyapatite and its compositions with collagen, sulphated glycosaminoglycans such as keratan and chrondroitin sulphate as well as with sulphate and calcium phosphate.After the graft material is placed in the socket, it is then covered with a resorbable or non-resorbable membrane and sutured. Primary flap closure is not ideal. Most importantly, socket preservation helps to maintain the alveolar architecture. Socket preservation significantly reduces the loss of ridge width and height following tooth removal.

Abstract: Oral squamous cell carcinoma (OSCC) constitutes 90% of oral cancer. Early detection is a cornerstone to improve survival and to reduce diagnostic delay. We propose optical coherence tomography (OCT), as a non-invasive diagnosis method. OCT represents a new high-resolution optical technique that permits 3D, real-time imaging of near surface abnormalities in complex tissues. In the present study half of the excisional biopsy was directed to the pathologist and the other half was assigned for OCT and Micro-CT investigation. For the OCT imaging it was used an OCT prototype (1300 nm), Synchrotron Radiation Micro-CT and histopathology validated the results. Areas of OSCC of the buccal mucosa were identified in the OCT images by the disruption of the basement membrane, an epithelial layer that was highly variable in thickness, with areas of erosion, extensive epithelial down-growth and invasion into the sub-epithelial layers. In this respect, OCT seems to be a highly promising imaging modality.

Abstract: Introduction. The osteoconductive materials are very important in the bone regeneration procedures. The aim of this paper is to evaluate the interface between the old bone and the new regenerated one.Materials and methods. Ten rat femurs were used for this investigation. Under strict supervision, ten holes were drilled in the rat femurs and then filled with Bio-Oss® (Geistlich, Wolhusen, Switzerland). matrix. The samples were obtained after 3 month from the procedure and were investigated by MicroCT. A common Synchrotron Radiation X-Ray micro-CT experiment was performed at the SYRMEP Beamline of the ELETTRA Synchrotron Radiation Facility (Trieste, Italy). The 900 radiographic projections were acquired with a beam energy of 29 keV over 180° (0.2 degrees step) with a resolution of 9μm. A sample – detector distance of 16 cm was considered. The tomographic reconstruction was performed by means of the common filtered back-projection method. The 3D reconstructions were obtained at the University of Ancona using specific software, VGStudio Max.Results: The synchrotron offered 900 microCT files that were used to make the 3D reconstruction of the bone. After tomographic reconstruction, 3D renderings of obtained data may be made by electronically stacking up the slices. These 3D volumes may be also sectioned in arbitrary ways, zoomed and rotated in order to locate better the individual details. While the 2D slice images and 3D renderings are very useful for making qualitative observations of an internal concrete structure, the real benefit is the quantitative information that can be extracted from the 3D datasets.The reconstructions allow observing the normal rat bone, the new regenerated bone and also the rest of nonactivated matrix of Bio-Oss® (Geistlich, Wolhusen, Switzerland). The system permits to make measurements in order to quantify the volume of the new bone formation and also the status of the bone defect, in order to define the healing process.Conclusions: The MicroCT method proves to be an important imagistic tool for nondestructive evaluation of the interface between the new regenerated bone and the old one from the rat femurs. This method allows numerical quantification of the new regenerated bone and define the healing bone process.

Abstract: Introduction: An orthodontist has two clinical situations in which he is confronted with ceramics: 1. Use of ceramic brackets 2. Applying brackets on teeth with ceramic restorations. Aim: The present study wishes to emphasize the advantages and the disadvantages that the use of ceramics has brought to the orthodontic profession. Material And Method: 75 consecutive adult orthodontic patients after being presented with their treatment plan were administered a questioner to motivate their choice in the type of braces and the cases with aesthetic braces or which had ceramic restorations prior to orthodontics received a special follow-up threw-out their treatment. Results: Ceramic braces are chosen for aesthetic reasons but sometimes they create other type of problems during treatment. Adhesion between braces and ceramic restorations rests problematic. Conclusions: The use of ceramics in orthodontics was indispensable but dental materials still need to be perfected.

Abstract: The final color of all-ceramic restorations may be influenced by the varying thickness of the dental abutment. Eighty A2 color (MO and LT) ceramic discs and eighty A3.5 color and four different thicknesses composite discs of were produced. The measurements were performed using the Vita Easyshade spectrophotometer. The results were statistically analyzed. Conclusion: There are no significant differences (perceived by the human eye) of the color parameters in the CIE L*a*b* system when comparing different combinations.

Abstract: Purpose: To establish the incidence of chipping of zirconia-based restorations, either implant or tooth supported in a retrospective study. Material and methods: Sixty patients received 222 cemented units of zirconia-based restorations. One hundred thirteen units were cemented on teeth, 97 on implants and 12 units were pontics. After the delivery of the restorations, during the recalls, the patients were examined in regard to the presence of chipping of the veneering ceramic. Location of the restoration, the type of support and the design of the restoration were assessed as possible factors influencing chipping rate. Results: During an observation period of up to 5,5 years, 27 (12,16%) zirconia-based units showed chipping of the veneering ceramic. A total of 14 units had to be remade, resulting in a survival rate of 93,69% of the zirconia-based restorations. The chipping rate seemed to be higher in restorations on implants than those supported by teeth. In the molar region chipping occured twice as often as in the premolar and front regions (15,83% vs 7,84%). An increased chipping rate was observed in multi-unit restorations (13,95%) as compared to single-unit restorations (9,67%). Conclusion: Chipping of the porcelain veneering is the most frequent complication of zirconia-based restorations. They should be recommended with care in the molar region, especially as multi-unit restorations.