Denture teeth can be made of acrylic poly(methyl methacrylate) (PMMA) or composite resins. PMMA is a polymer - a material made the from joining of methyl methacrylate monomers. Properties of PMMA include resistance to abrasion, chemical stability and a high boiling point. (Jun Shen et al. 2011). However, weak flexure and impact strength of PMMA are of concern as they account for denture failure. (Bolayir G, Boztug A and Soygun K. 2013). Composite denture teeth are made of a three distinct phases - filler, matrix and coupling agents. Out of the types of composite teeth available, nano-filled composite teeth are preferred. Composite teeth have a PMMA coating around the tooth and a high content of filler particles. This gives them strength, higher resistance to forces than acrylic teeth and provides compete polymerization due to the PMMA coating. (Anusavice, K. J., Phillips, R. W., Shen, C., & Rawls, H. R, 2012). If the interface between the PMMA denture base and PMMA or composite teeth was weak, the denture will not be able to sustain occlusal forces, making the base-teeth interface, an entity of significance.
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...
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...an be seen that composite teeth form a high stability bond than PMMA teeth. This is due to the filler content allowing for low shrinkage, increased wear resistance and better cross-linkage with the base. In overall consensus the technique of heat-curing is believed to achieve significantly more polymer cross-linkage than that of self-curing the acrylic resin PMMA base - giving us a stronger base to teeth interface. It should be noted however that both techniques can be used for denture fabrication to achieve a desired result and it is up to the dentist and the technician to determine which one they prefer however, composite teeth bonded to a heat-cured PMMA base works best. Though the tooth and base by themselves may be strong, if the interface between them is not strong, this will result in the overall denture produced being weak independent of material selection.
Ceramics are most commonly used in dental applications as restorative materials for crowns, cements and dentures.
STRUCTURE Kevlar Aramid Fiber is a synthetic (man-made) material known as Polymer. A polymer is a chain that is made up of many similar molecular groups, better known as ‘monomers’ that are bonded together. The ‘Monomers’ are made up of fourteen Carbon atoms, two Nitrogen atoms, two Oxygen atoms and ten Hydrogen atoms. A single Kevlar polymer chain could possibly have anywhere from one to five million monomers bonded together. A group of polymer chains can be organised together in a fiber.
In recent years the discussion of whether dental amalgam is safe for use in filling caries has been a hot topic. In this project I will give an explanation of what dental amalgam is, mentioning and highlighting its beginnings in dentistry and how it became the most used restorative material to date. I will also be mentioning the reason there is so much controversy surrounding its use, and the basis for these questions. This will include information gathered from research collected by various scientists. Also mentioned will be the different restorative materials that came by due to the dental amalgam controversy.
Throughout the history of dental medicine dentist have searched for the perfect material to aid in the treatment of the most common problem in people’s mouths, cavities. The material would also be useful in fixing chipped and broken teeth. Dentist needed a material that was strong, relatively low costing, easy to apply, durable, and able to limit the growth of bacteria. In the early 19th century in France dentist found their wonder material and that material was amalgam. The dental amalgam is constructed of a mixture of mercury and at least one other metal such as zinc, copper, tin, or silver. The combinations of these metals are the foundation of what gives silver amalgams their strong make up and shiny metallic appearance.
Throughout the history of dental medicine dentist have searched for the perfect material to aid in the treatment of the most common problem in people’s mouths, cavities. The material would also be useful in fixing chipped and broken teeth. Dentist needed a material that was strong, relatively low costing, easy to apply, durable, and able to limit the growth of bacteria. In the early 19th century in France dentist found their wonder material and that material was amalgam. The dental amalgam is constructed of a mixture of mercury and at least one other metal such as zinc, copper, tin, or silver. The combinations of these metals are the foundation of what gives silver amalgams their strong make up and shiny metallic appearance.
Suleiman, S.H. Steyern, P.V.V. (2013), Fracture strength of porcelain fused to metal crowns made of cast, milled or laser-sintered cobalt-chromium. Acta Odontologica Scandinavica, pp.1-10.
Polyethylene (PE) is one of the most commonly used polymers which can be identified into two plastic identification codes: 2 for high-density polyethylene (HDPE) and 4 for low density polyethylene (LDPE). Polyethylene is sometimes called polyethene or polythene and is produced by an addition polymerisation reaction. The chemical formula for polyethylene is –(CH2-CH2)n– for both HDPE and LDPE. The formation of the polyethylene chain is created with the monomer ethylene (CH2=CH2).
The glass-infiltrated oxide ceramic framework consists of a porous pre-sin¬tered ceramic core that is subsequently infiltrated with a low-viscosity glass. The ceramic core can be fabricated in the dental lab either by slip casting ceramic powder slurry on a porous refractory die, or by milling out from a pre-fabricated CAD/ CAM ceramic block made by powder dry pressing9, 19, 21, 25. The oxide ceramic framework can be fabricated from different oxide materials and infiltrated by different glass materials. The available used oxide ceramics are aluminum oxide (Al2O3), magnesium aluminum oxide (MgAl2O4), and zirconium oxide (ZrO2). Glass-infiltrated Oxide Ceramics were first introduced in dentistry as In Ceram ® Alumina in 1989. It consists of 75
•Like an inlay, a white filling fills a hole in the tooth. Instead of porcelain, a composite resin is used. While this material is not as strong as porcelain, it is still durable.
Tooth colored composites are a mixture of submicron glass filters and acrylic that form a tooth colored restoration. The main advantage of composites are seen when mentioning aesthetics. The color of the fillings can be matched to that of the tooth. This is why they are used in the anterior teeth. A unique feature of this filling is its ability to chemically bond to the tooth struct...
Our analysis revealed that Affinis® had more dimensional stability in comparison to Panasil® and in the Panasil® impression material, the percentage of dimensional change was significant after 168 h. However, dimensional changes in all of the evaluation times were in the American Dental Association (ADA) standard range. Therefore, these materials had acceptable clinical dimensional stability for approximately 168 h. In the current study, impressions were made from stainless steel dies following the ADA specification for impression materials. This provides a protocol that can be easily replicated by others and it is the same as making a clinical
There are two types of materials most commonly used for dental veneers: composite resin and porcelain. Both are or can be made by a dental technician in a lab and both are used to bond your veneers to your teeth. However porcelain is extremely brittle until it is bonded with the veneer and your teeth, then it is strong and durable like the composite resin.
The choice of restorative material is considered to be one of the most important factors for the success and reliability of any restorative system. Composite resin gained popularity among clinicians due to its ease of handling, excellent esthetic and mechanical properties, and reported ability to reinforce weakened dental structure. (73) However, when a cavity preparation exceeds the recommended limits for the direct application of composite resins, indirect total- or partial-coverage restorations have been indicated.
Then, the teeth will be isolated with rubber dam (Hygienic Dental Dam, 2010). High and low volume saliva ejectors will be used additionally for suction of saliva and water from high speed hand piece. During preparation beveling of the enamel margins will be carried out for both groups to increase the surface area of enamel. The same set of burs and instruments will be used for preparation in both groups. Further, for the intervention group the enamel will be selectively etched for 15 seconds with 37% phosphoric acid followed by rinsing and drying of tooth. The one- step adhesive will then be applied to both enamel and dentin (Brady, 2013) with a micro tip applicator. Whereas, for the control group only the 1- step adhesive will be applied onto the prepared cavity. Furthermore, the adhesive will be cured with Mini LED light by Dentsply which has an intensity of 1250 mW/cm² (Adec, 2016). After curing of the bond, composite layering will be carried out by an incremental (0.5mm) placement of composite resin and cured with the same curing light to eliminate bias between the curing efficiency of different lights (Esmaeili, Safarcherati and Vaezi, 2014). Same set of instruments will be used for freehand shaping of composite between groups. A cellulose plastic matrix band and a wedge is used to contour the restoration interproximally (Chandra, S., Chandra, S. and Chandra, G. 2007). A microfilled composite resin [Filtek™ Z250 (3M ESPE)]
In some in vitro studies, fiber-reinforced composites (FRCs) have been also employed to reinforce cusp- replacing restorations. (69; 70; 71) Besides improving the strength of the restoration, results of these studies demonstrate that the incorporation of glass fibers into composite resin materials usually leads to more favorable fracture patterns above the CEJ because the fiber layer acts as a stress breaker and stops the crack propagation. Furthermore, and especially for endodontically treated teeth, this composite base reinforces cavity walls during the temporary phase.