Due to stringent regulations regarding the emission of volatile organic compounds, there is a demand to develop fast setting solvent free resins. Light cured materials have many advantages over conventional chemically cured adhesives, including consistent handling characteristics, single paste application, and easy removal of excess material and extended working time.1 UV-curable adhesives appear to be ideal candidates since such liquid formulations contain no organic solvents and are readily transformed into solids by a short exposure to UV-radiation at ambient temperature. This feature, together with the resulting low consumption of energy and the high performance of the UV-cured materials, explains the increasing use of this environment-friendly …show more content…
Dual curable systems could effectively overcome the shortcomings of need for at least one transparent substrate and limited depth of cure. Other disadvantages were taken care of by the development of a new class of adhesives known as visible light curing adhesives.3 Moreover overexposure to UV light can result in skin problems and even skin cancer. Irradiation using visible light instead of UV light could offer many advantages in biomedicine, without losing the advantages of photocuring.The majority of modern resin-based oral restorative biomaterials are cured by photopolymerization processes. Various light sources such as quartz-tungsten-halogen (QTH) bulbs, laser, plasma arc lights, and light emitting diodes (LEDs) can be used for light curing of dental …show more content…
The tack of the UV-crosslinked acrylic adhesives decreased with the increase in the photoinitiator concentration. Polymeric photoinitiators were synthesized using polyacrylates having benzophenone incorporated into their backbones and blended with Hydrogenated rosin epoxy methacrylate (HREM; based on hydrogenated rosin and glycidyl methacrylate) synthesized as a tackifier.6 It was observed that probe tack decreased because of the increased consumption of benzophenone groups with increasing UV dose. Rate of the decrease in the relative benzophenone concentration decreased with increasing hydrogenated rosin content in the PSA blends indicating that the hydrogenated rosin acted as a UV-curing retardant.Reactivity of the functional group, its concentration, the viscosity of the resin, as well as the intensity of the UV-radiation influences the rate of the rate of
This experiment was conduct to investigate the fluorescent behaviour of Leucophor PAF and to investigate the quenching of QBS with NaCl. It was found that the Leucophor PAF indeed satisfied the characteristic to act as whitening agent. It was also found that the quenching of QBS with NaCl was a diffusion-controlled collision process.
Khosravi K, Ataei E, Mousavi M, et al. Effect of Phosphoric Acid Etching of Enamel Margins on the Microleakage of a Simplified All-in One and Self-etch Adhesive System. Operative Dentistry 2009; 34(5):531-36.
I believe that Lewis ends the book on such an ambiguous note to demonstrate the persistence of Screwtape’s lack of understanding of God and the power falsely held belief can have over others. This ambiguous view is used as a warning of the power of temptation. Screwtape firmly holds on to the belief of "the conviction that our Realism, our rejection (in the face of all temptations) of all silly nonsense and claptrap, must win in the end” because Screwtape lives with the guarded desperate thought that the kind of relationship God desires with humans places him at an unmistakable disadvantage, but he is always on guard to not be weakened by this realization. The warning that readers receive with the novel’s ending is that
In this work, the mechanical and barrier properties were examined for Polypropylene (PP) film in which the surface of the film was modified by Oxygen plasma treatment. The PP film was treated in various intervals of time of 60 s, 120 s, 180 s, 240 s and 300 s with three various RF power settings of 7.2 W, 10.2 W, 29.6 W. The contact angle was measured to characterize the wettability. The oxygen functional groups were generated on the surface of oxygen modified PP which was observed by Fourier transform infrared spectroscope and it was resulted in the improvement of wettability. The surface morphology and roughness of the PP films before and after the oxygen plasma treatment was analyzed by Atomic Force Microscopy (AFM). It was found that the roughness of
Dr. Gary Silva and his team are highly trained and experienced in providing restorations for all sorts of dental issues. We offer complete and partial dentures, tooth-colored fillings, crowns, bridges, and more. Dr. Silva’s unique background gave him real restorative experience early in his career. For more than 20 years, Dr. Silva has been offering patients the chance to gain a beautiful, functional smile with his restorative dentistry.
Because of its ability to break down self-associative tendency of water , it may also reduce the number of water molecules entrapped between the polymeric chains, increasing the degree of postoperative polymerization In addition to post-curing increase in bond strength, the relative decrease in free water would eliminate or decrease the hydrolytic degradation of adhesive in or above the hybrid layer
After the treatment and procedure is complete, patients leave with healthier, more beautiful teeth, giving them the confidence to ask someone out on a date or the confidence to smile on an important job interview. Dentistry is and has been for centuries, an important aspect of people’s ...
In my opinion, the use of Super Glue and its family of cyanoacrylates will not end. When something needs to be attached quickly usually people will reach for Super Glue or other products just like it. When different materials are added different adhesives can be made. Nature has no known substance that can do the same job.
The contraction moulding method can be used to process an acrylic denture base. In this method, bite blocks are fabricated in the lab and sent to the clinic for patient trial. These are then received from the clinic and teeth are mounted onto the bite blocks. The wax is eliminated and teeth are pressurized and attached onto a gypsum mould. (McCabe and Walls. 2008.) Sodium alginate is applied onto the mould to act as a separator to prevent any monomer from the acrylic base seeping into the base and the mould. Acrylic PMMA is applied onto the mould and either heat-cured or auto-polymerized. Both of these curing methods form the...
chains instead of hydrogen atoms. Cross-linking is another way in which the polymer can be made stronger. This involves ultraviolet radiation that bombards the polymer with electrons and formulates bonds between the molecular chains of the polymers. This is like linear polyethylene but different in that it is more impact resistant, and it has a much higher density. This allows it to be stored or be used with different chemicals that would normally cause the polymer to desolve.3 This can start to become a problem because as the polymer continues to become chemically enhanced. So the ways of dissolving and recycling the polymer become more difficult.
Impression materials are used to register or reproduce the form and relations of the teeth and the surrounding oral tissues (1). Making an impression represents a critical step in processing and fitting of a dental prosthesis (2). Several types of impression materials are produced. These include silicones, polyether, polysulfide and alginate which are available for crowns and fixed partial denture impressions. Silicone impression materials are considered to be suitable impression materials to use for fixed prostheses (3). Also, it has been reported that silicone has the ability to remain dimensionally stable through disinfection procedures (4). Among silicone impression materials, one type of them, called polyvinyl siloxane (PVS) is reported
Acrylic nail is an artificial nail which is glued on the natural nail. These acrylic nails are formed by combining a liquid (EMA, i.e., Ethyl Methacrylate or MMA, i.e., MethylMethacrylate) and a powder. The nails made of EMA are generally more long-lasting and flexible than those made of MMA. MMA nails might be cheaper, but often they cause skin irritation. So it’s always recommended to go for acrylic nails made up of EMA.
Cosmetic dentistry is a specialized field that deals with improving the aesthetics of teeth and the human face. The teeth are an important part of human beauty. Even minor damage to the teeth, such as breakage or loss can drastically alter the overall appearance of the face. This is where cosmetic dentistry comes in to restore beauty. Cosmetic dentistry has become a highly specialized branch due to various advancements in surgical procedures and diagnostic techniques. Several new materials have also been discovered. These materials are very close to the natural enamel and bone from which teeth are made and are virtually indistinguishable. Cosmetic dentistry is an option in conditions such as teeth loss, gaps between teeth, cracked or chipped teeth, cavities and dental
9. Siso HS, Kustarci A, Göktolga EG. Microleakage in Resin Composite Restorations After Antimicrobial Pre-treatments: Effect of KTP Laser, Chlorhexidine Gluconate and Clearfil Protect Bond. Oper Dent. 2009; 34(3): 321-327.
Everyone has heard a cashier one time or another mumble, “Paper or plastic?” as he put their groceries in a bag, but do shoppers know the effects of each vessel in which they carry their comestibles? There are many issues and benefits to both paper and plastic. The making and recycling of both paper and plastic bags can harm the environment. One must also look at the costs of making each bag. The convenience of each is also something to look at. Many people jump to conclusion that paper bags are better for the environment without knowing the facts. Since plastic bags are preferred by customers and plastic bags actually do not hurt the environment as much as paper ones do, consumers should feel at ease when choosing plastic.