Amorphous calcium phosphates: synthesis, properties and uses in biomaterials

This review paper on amorphous calcium phosphates (ACPs) provides an update on several aspects of these compounds which have led to many studies and some controversy since the 1970s, particularly because of the lack of irrefutable proof of the occurrence of an ACP phase in mineralised tissues of vertebrates. The various synthesis routes of ACPs with different compositions are reported and the techniques used to characterise this phase are reviewed. We focus on the various physico-chemical properties of ACPs, especially the reactivity in aqueous media, which have been exploited to prepare bioactive bone substitutes, particularly in the form of coatings and cements for orthopaedic applications and composites for dental application

Biomaterials for Orthopaedic, Gynaecological, Ophthalmic, Surgical and Dental Applications

Proceedings of"Conference on Recent Advances in Biomaterials Dec 17-18 '10"Held at Saveetha School of Engineering, Saveetha University, Thandalam, Chennai-602 105, Tamilnadu, IndiaTheme 1 Biomaterials for Orthopaedic, Gynaecological, Ophthalmic, Surgical and Dental Application

Advanced Materials for Oral Application

This book consists of one editorial, 12 original research articles and two review papers from scientists across the world, with expertise in materials for dental application. The main subjects covered are: biomaterials and techniques for oral tissue engineering and regeneration; biomaterials for surgical reconstruction; CAD/CAM technologies and dedicated materials; novel restorative and endodontic materials and instruments

Active noise control for high frequencies

There are many applications that can benefit from Active Noise Control (ANC) such as in aircraft cabins and air conditioning ducts, i.e. in situations where technology interferes with human hearing in a harmful way or disrupts communication. Headsets with analogue ANC circuits have been used in the armed forces for attenuating frequencies below 1 kHz, which when combined with passive filtering offers protection across the whole frequency range of human hearing. A dental surgery is also a noisy environment; in which dental drill noise is commonly off-putting for many patients and is believed to harm the dentist’s hearing over a long period of time. However, dealing with dental drill noise is a different proposition from the applications mentioned above as the frequency range of the peak amplitudes goes from approximately 1.5 kHz to 12 kHz, whereas conventional ANC applications consider a maximum of 1.5 kHz. This paper will review the application of ANC at low frequencies and justify an approach for dealing with dental noise using digital technologies at higher frequencies. The limits of current ANC technologies will be highlighted and the means of improving performance for this dental application will be explored. In particular, technicalities of implementing filtering algorithms on a Digital Signal Processor will be addressed

bioactive nanocomposites for dental application obtained by reactive suspension method

AbstractHydroxyapatite (HA) filled poly(methyl methacrylate)/poly(hydroxyethyl methacrylate) (PMMA/PHEMA) blends were prepared by reactive suspension method: HA was synthesized by co-precipitation process directly within a HEMA solution and the so-obtained suspension was polymerized in the presence of PMMA. HA particles were obtained in form of nanorods with a length of 50–200 nm and a diameter of 10–30 nm. A significant increase in glass transition temperature was observed in the nanocomposites with respect to the unfilled polymer blends. Dynamic-mechanical thermal analysis showed a significant increase in the storage modulus in the nanocomposites measured in the rubbery region. This increase was unpredicted by Mooney's predictive equation and was attributed to the presence of cross-linking points due to the in situ generated HA particles. An increase in the elastic modulus was also observed at room temperature in compression and three-point bending tests. The presence of HA in the polymer blends resulte..

Development of a novel resin with antimicrobial properties for dental application

The adhesion of biofilm on dental prostheses is a prerequisite for the occurrence of oral diseases. Objective: To assess the antimicrobial activity and the mechanical properties of an acrylic resin embedded with nanostructured silver vanadate (β-AgVO3). Material and Methods: The minimum inhibitory concentration (MIC) of β-AgVO3 was studied in relation to the species Staphylococcus aureus ATCC 25923, Streptococcus mutans ATCC 25175, Pseudomonas aeruginosa ATCC 27853, and Candida albicans ATCC 10231. The halo zone of inhibition method was performed in triplicate to determine the inhibitory effect of the modified self-curing acrylic resin Dencor Lay - Clássico®. The surface hardness and compressive strength were examined. The specimens were prepared according to the percentage of β-AgVO3 (0%-control, 0.5%, 1%, 2.5%, 5%, and 10%), with a sample size of 9x2 mm for surface hardness and antimicrobial activity tests, and 8x4 mm for the compression test. The values of the microbiologic analysis were compared and evaluated using the Kruskal-Wallis test (α=0.05); the mechanical analysis used the Shapiro-Wilk's tests, Levene's test, ANOVA (one-way), and Tukey's test (α=0.05). Results: The addition of 10% β-AgVO3 promoted antimicrobial activity against all strains. The antimicrobial effect was observed at a minimum concentration of 1% for P. aeruginosa, 2.5% for S. aureus, 5% for C. albicans, and 10% for S. mutans. Surface hardness and compressive strength increased significantly with the addition of 0.5% β-AgVO3 (p;0.05). Conclusions: The incorporation of β-AgVO3 has the potential to promote antimicrobial activity in the acrylic resin. At reduced rates, it improves the mechanical properties, and, at higher rates, it does not promote changes in the control

Development of a 3D Printing Method for Production of Dental Application

Traditionally, the manufacturing of dental restorations, including crowns, veneers and other structures made by ceramics, is a labor‐intensive and time consuming process. Additive manufacturing has the potential to significantly decrease the time and cost associated with this process. This work performed preliminary investigation for the feasibility of dental restoration parts printing using the ExOne M‐Lab system with a commercialized dental porcelain powder. The porcelain powders were characterized, and two measurements, including pre‐sintering and addition of flow agent, were taken in the attempt to improve the processability of the original powder feedstock. The results showed that while the addition of flow agent has more significant effects in improving the flowability of the powder used, the post sintered parts exhibit considerable shrinkage and residual porosity that necessitates further investigation.Mechanical Engineerin

In Vivo Effect of a Nisin–Biogel on the Antimicrobial and Virulence Signatures of Canine Oral Enterococci

Research Areas: Infectious Diseases ; Pharmacology & PharmacyABSTRACT - Periodontal disease is a relevant oral disease in dogs and nisin–biogel has been previously proposed to be used in its control. Enterococci, as inhabitants of the oral cavity with a high genetic versatility, are a reliable bacterial model for antimicrobial studies. Our goal was to evaluate the in vivo influence of the long-term dental application of the nisin–biogel on the virulence and antimicrobial signatures of canine oral enterococci. Twenty dogs were randomly allocated to one of two groups (treatment group—TG with nisin–biogel dental application, or control group—CG without treatment) and submitted to dental plaque sampling at day 0 and after 90 days (T90). Samples were processed for Enterococcus spp. isolation, quantification, identification, molecular typing and antimicrobial and virulence characterization. From a total of 140 enterococci, molecular typing allowed us to obtain 70 representative isolates, mostly identified as E. faecalis and E. faecium. No significant differences (p > 0.05) were observed in the virulence index of the isolates obtained from samples collected from the TG and CG at T90. At T90, a statistically significant difference (p = 0.0008) was observed in the antimicrobial resistance index between the isolates from the TC and CG. Oral enterococci were revealed to be reservoirs of high resistant and virulent phenotypesinfo:eu-repo/semantics/publishedVersio

Marketability and Feasibility of Chair-Side Gas Chromatography Mass Spectrometer for Dental Application

poster abstractDental caries, commonly known as cavities, is the most common disease of childhood, but affects all ages. The first signs of dental caries (early lesions) can be seen before the cavitation is observed. If left untreated, the early lesions can progress to cavitation. Treatment provided at the early stages can prevent progression and avoid the traditional surgical/restorative treatment which does not prevent reoccurrence or stops progression of the disease. The challenge faced by dentists is the ability to accurately identify tooth sites at risk for lesion initiation and progression. Currently, no technology exists that has the ability to accurately assess a site and determine whether or not that surface will develop a lesion or if an existing lesion will progress towards cavitation. On-going research at the Oral Health Research Institute has shown that biofilm samples collected from caries active sites in children have distinguishably different metabolite signals when compared to caries-free sites. These signal profiles were determined using Gas Chromatography Mass Spectrometer (GCMS) analysis. The ability to provide such signature profiles during a typical dental examination may allow for early identification of surfaces and patients at risk and institution of preventative measures to be taken much sooner. In order to reach this stage of mass use of this technology for this specific application, diligent analysis of the possible market and customer of this signature product must be conducted. The three key populations surveyed and interviewed for the marketability and feasibility of this product were mass spectrometer experts and manufacturers, practicing dentists, and policy makers and individuals with expertise in dental insurance. Although the project is ongoing and results are inconclusive, these key informants will provide answers on whether or not a GCMS for this application is viable, the likelihood of dentists using the product aforementioned, cost structures of production and marketing, and key partner relationships with insurance companies. These findings will provide an initial indication of the success of this technology in a predetermined market, but it may also open unforeseen opportunities in other markets

Anodized Nanoporous Titania Thin Films for Dental Application: Structure’ Effect on Corrosion Behavior

Nanostructured Titania layers formed on the surface of titanium and titanium alloys by anodic oxidation play an important role in the enhancement of their biocompatibility and osseointegration in the human body. For this purpose, we aimed to study in the current work the structural and electrochemical properties of amorphous and crystallized nanostructured TiO2 thin films elaborated on Ti6Al4V substrate by electrochemical anodization in fluoride ions (F–) containing electrolyte at 10 V during 15 min and heat treated in air at 550 °C for 2 h. The morphology, chemical composition and phase composition of synthesized layers were investigated using field emission scanning electron microscopy (FE-SEM) and X-ray diffraction (XRD). The corrosion resistance improvement of both as-anodized and annealed titania layers was evaluated in 0.9 wt. % NaCl solution with pH = 6.4 at room temperature by means of open circuit potential (Eoc),potentiodynamic polarization (PDYN) and electrochemical impedance spectroscopy (EIS)