Dental composite

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Dental composite resin (preferably referred to as " resin-based composites " or simply "filled resin ") is a type of synthetic resin used in medicine teeth as a restorative material or adhesive. Dental composite resins have certain properties that will benefit patients according to the patient's cavity. It has a micro-mechanical property that makes composites more effective for filling small cavities where amalgam fillings are ineffective and can therefore fall (due to macro-mechanical properties of amalgam). Synthetic resins evolved as a restorative material because of insoluble, good dental appearance, insensitive to dehydration, easily manipulated, and reasonably priced. The most common composite resins consist of Bis-GMA and other dimethacrylate monomers (TEGMA, UDMA, HDDMA), fillers such as silica and the most recent application, a photographer. Dimethylglyoxime is also generally added to achieve certain physical properties such as flowability. Further adjustment of physical properties is achieved by formulating the unique concentrations of each constituent.

Many studies have compared the longevity of resin-based composite restorations to long-life amalgam silver-mercury restorations. Depending on the skill of the dentist, patient characteristics and type and location of damage, composite restorations may have the same resilience as amalgam restorations. (See Longevity and Clinical Performance.) Compared with amalgam, the appearance of resin-based composite restorations is far superior.

Video Dental composite

History of use

Traditional resin-based composites are regulated by chemical regulatory reactions through polymerization between two pastes. One paste contains an activator (not a tertiary amine, as this causes a discoloration) and the other contains an initiator (benzoyl peroxide). To overcome the disadvantages of this method, such as short working time, curing resin composites were introduced in the 1970s. The first light-curing unit uses ultra-violet light to regulate the material, but this method has a limited cure depth and high risk for patients and doctors. Therefore, the light-curing UV unit was subsequently replaced by a visible light-curing system that used Camphorquinone as a light source and overcome the problems generated by the UV light-curing unit.

Periode Tradisional

In the late 1960s, composite resins were introduced as an alternative to unmet silicates and resins, often used by doctors at the time. Composite resins exhibit superior quality, because they have better mechanical properties than silicates and unmet resins. Composite resins also look useful because the resins will be presented in pasta form and, with pressure techniques or easy mass insertion, will facilitate clinical management. The fault with the current composite resin is that they have poor appearance, poor marginal adaptation, difficulty with polishing, difficulty with adhesion to the tooth surface, and sometimes, loss of anatomical shape.

Periode Microfilled

In 1978, various microfilled systems were introduced to the European market. These composite resins are attractive, because they are capable of having very smooth surfaces when finished. These microfilled composite resins also exhibit better clinical color stability and higher resilience to wear than conventional composites, which favored appearance as their dental tissue as well as clinical effectiveness. However, further studies show progressive weakness in the material over time, leading to micro cracks and loss of materials such as steps around the composite margin. In 1981, microfilled composites increased remarkably with regards to marginal retention and adaptation. It was decided, after further research, that this type of composite could be used for most restorations provided the etching acid technique was used and the bonding agent was applied.

Periode Hibrida

Composite hybrids were introduced in the 1980s and are more commonly known as resin-modified resin ion certs (RMGICs). The material comprises a powder containing a radio-opaque fluoroaluminosilicate glass and a photoactive liquid contained in a bottle or a dark capsule. The material is introduced, because the composite resin itself is not suitable for Class II cavities. RMGIC can be used instead. This mixture or resin and glass ionomer allow the material to be regulated by activation of light (resin), allowing longer working time. It also has the benefit of the glass ionomer component releasing fluoride and has superior adhesive properties. RMGIC is now recommended over traditional GICs for basing cavities. There is a big difference between the initial and new hybrid composites.

Initially, resin-based composite restorations in dentistry are particularly vulnerable to leakage and damage due to weak compressive strength. In the 1990s and 2000s, such composites were greatly increased and had sufficient compression strength for use in posterior teeth.

Maps Dental composite

Clinical methods and applications

The current composite resin has a low polymerization shrinkage and a low heat shrink coefficient, which allows it to be placed in large quantities while maintaining a good adaptation to the cavity wall. Composite placement requires careful attention to procedures or may fail prematurely. The teeth should be kept perfectly dry during placement or the resin will likely fail to stick to the teeth. The composite is placed while still in soft state, like a dough, but when exposed to light with a certain blue wavelength (usually 470 nm), polymerize and harden into a solid charge (for more information see Light activated resin). It's challenging to harden all composites, because light often does not penetrate more than 2-3 mm into composites. If too thick a composite number is placed in the tooth, the composite will remain partially soft, and the soft unsololized composite may eventually lead to leaching of the free monomer with potential toxicity and/or leakage from the bonded joint leading to repeated dental pathology. The dentist should place the composite in large quantities in various additions, heal each section 2-3 mm before adding the next one. In addition, doctors should be careful to adjust the bite of composite filling, which can be difficult. If the filling is too high, even with a smooth amount, it can cause a sensitivity to chew on the teeth. Properly placed composites are comfortable, good looking, strong and durable, and can last 10 years or more. (By most North American insurance companies a minimum of 2 years)

The most desired final surface for composite resins can be provided by aluminum oxide discs. Classically, Class III composite preparations are required to have a retention point located entirely on the dentin. A syringe is used to place composite resins because the possibility of trapping air in the restoration is minimized. Modern techniques vary, but conventional wisdom suggests that because of the large increase in bond strength due to the primary use of dentine in the late 1990s, physical retention is not necessary except for the most extreme cases. Primer enables the dentine collagen fibers to be "squeezed" into the resin, resulting in superior physical and chemical bonding from filling to the teeth. Indeed, the use of composites was highly controversial in the field of teeth until primary technology was standardized in the mid to late 1990s. The enamel lining of the composite resin preparation should be tilted to improve the appearance and expose the tip of the enamel rod for acid attack. Proper enamel dyeing techniques before placement of composite resin restorations include etching with 30% -50% phosphoric acid and rinsing with water and drying only with air. In preparing cavities for restorations with composite resins combined with acid etching techniques, all angles of the enamel cavosurface should be dull angles. Contraindications to composites include varnish and zinc oxide-eugenol. Composite resins for Class II restorations were not indicated for excessive occlusal use in the 1980s and early 1990s. Modern bonding techniques and the increasingly unpopularity of amalgam fillers have made composites more appealing for Class II restorations. Opinions vary, but composites are considered to have sufficient longevity and wear characteristics used for permanent Class II restorations. Whether the composite material is durable or has leakage and sensitivity when compared to Class II amalgam restorers is described as a matter of debate in 2008.

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Composition

Like other composite materials, dental composites typically consist of resin-based oligomer matrices, such as bisphenol A-glycidyl methacrylate (BISGMA), urethane dimethacrylate (UDMA) or [(semi-crystalline polyceram]] (PEX), and an inorganic filler such as silicon dioxide (silica). Without filler, the resin is easy to use, indicating high shrinkage and exothermic. The compositions vary greatly, with a special mixture of resin forming the matrix, as well as the filling glass and ceramic glass being engineered. Fillers provide greater composite strength, wear resistance, reduced polymerization shrinkage, improved translucency, fluorescence and color, and less exothermic reactions in polymerization. But it also causes the resin composite to become more brittle with increasing modulus of elasticity. Glass fillers are found in a variety of different compositions allowing an increase in the optical and mechanical properties of the material. Ceramic fillers include zirconia-silica and zirconium oxide.

Matrices such as BisHPPP and BBP, which are contained in the universal BiSGMA adehsive, have been shown to increase the cariogenicity of bacteria leading to secondary caries in the dentine-composite interface. BisHPPP and BBP cause an increase in glycosyltransferase in S. mutans bacteria, resulting in increased sticky glucan production that allows adhesion of S.mutans to teeth. This results in a cariogenic biofilm on the composite and dental interface. The bacterial cariogenic activity increases with the concentration of the matrix material. BisHPPP has subsequently been shown to regulate bacterial genes, making bacteria more cariogenic, thus sacrificing the longevity of composite restorations. The researchers highlight the need for new composite materials to be developed that eliminate the cariogenic products currently contained in composite resins and universal adhesives.

A coupling agent such as silane is used to increase the bond between these two components. Initiator packets (such as: camphorquinone (CQ), phenylpropanedione (PPD) or lucirin (TPO)) begin the polymerization reaction of the resin when blue light is applied. Various additives can control the reaction rate.

Type of filler and particle size

The resin filler can be made of glass or ceramic. Glass fillers are usually made of crystalline silica, silicon dioxide, lithium/barium-aluminum glass, and borosilicate glass containing zinc/strontium/lithium. Ceramic fillers are made of zirconia-silica, or zirconium oxide.

Fillers can be subdivided by size and shape of their particles such as:

Own filled filler

Macrofilled fillers have particle sizes ranging from 5 - 10 Âμm. They have good mechanical strength but poor wear resistance. The final restoration is difficult to polish enough to leave a rough surface, and therefore this type of resin is a plaque charge.

Microfilled charger

Microfilled fillers are made of colloidal silica with a particle size of 0.4 Ã,Âμm. This type of filler resin is easier to polish than macrofilled. However, its mechanical properties are compromised as the charger load is lower than conventional (only 40-45% by weight). Therefore, it is contraindicated to load situations, and has poor wear resistance.

Hybrid filler

Hybrid fillers contain particles of various sizes with 75-85% weight filler load. These are designed to benefit from macrofilled and microfilled fillers. Resins with hybrid fillers have reduced thermal expansion and higher mechanical strength. However, it has a higher polymerization shrinkage due to the larger volume of diluent monomers that controls the viscosity of the resin.

Nanofilled Content

Nanofilled composites have a particle size of 20-70nm filler. Nanoparticles form a nanocluster unit and act as a single entity. They have high mechanical strengths similar to hybrid materials, high wear resistance, and are easily polished. However, nanofilled resins are difficult to adapt to the cavity margin due to high filler volume.

Bulk filler

Bulk filler consists of unagglomerated silica and zirconia particles. It has nanohybrid particles and a loading load of 77% by weight. Designed to reduce clinical steps with the possibility of mild healing through an additional depth of 4-5mm, and reduce stress in remaining dental tissue. Unfortunately, it is not so strong in compression and has decreased wear resistance compared to conventional materials

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Benefits

Dental composites are directly placed by the dentist in a clinical setting. Polymerization is carried out specifically by hand-picking rays that emit specific wavelengths inserted into the initiator and the involved catalyst package. When using curing lights, the light should be held as close as possible to the resin surface, the shield should be placed between the end of the light and the operator's eyes. Curing time should be increased for darker resin colors. Light cured resin provides denser restorations than self-cured resins because no mixing is required which can introduce air bubbles porosity.

Direct dental composites can be used to:

• Fill in the cavity preparation
• Fill the gaps between the teeth using a shell-like veneer or
• Small tooth form
• A partial crown on a single tooth

Setting the resin composite mechanism

Setting mechanism type:

• Chemical medicine (self-healing/dark healing)
• Light healing
• Double healing (chemical and light settings)

Chemically preserved composite resins are two-stick systems (bases and catalysts) that begin to regulate when the base and catalyst are mixed together.

The lightweight resin composite composite contains photo initiators (eg camphorquinone) and accelerators. Activators present in light-activated composites are diethyl-amino-ethyl-methacrylate (amine) or ketones. They interact when exposed to light at a wavelength of 400-500 nm, that is, the blue region of the visible light spectrum. Composite sets when exposed to light energy at a set of wavelengths of light. The lightweight preserved composite resin is also sensitive to ambient light, and therefore, polymerization may be initiated prior to the use of curing light.

Dual resin preserved resins contain both photo-initiator and chemical accelerator, allowing the material to regulate even where there is sufficient light exposure for light curing.

Chemical polymerization inhibitors (eg, monomethyl ether hydroquinone) are added to the resin composite to prevent polymerization of the material during storage, increasing its shelf life.

Classification of resin composite according to handling characteristics

This classification divides the resin composite into three broad categories based on its handling characteristics:

• Universal: advocates the use of common, oldest subtypes of resin composites
• Flowable: liquid consistency, used for very small restoration
• Packed: more rigid, more viscous ingredients used only for mouthpiece

Manufacturers manipulate handling characteristics by altering material constituents. In general, rigid materials (bundled) exhibit higher filler contents while fluid material (flowed) indicates a lower filler charge.

Universal: This is a traditional presentation of resin composites and performs well in many situations. However, its use is limited in specific practices where more complex aesthetic treatments are performed. Indications include: class I, II and III and IV restorations where aesthetics are unimportant, and repair of non-dental carious tooth surface lesions (NCTSL). Contraindications include: ultraconservative cavity recovery, in areas where aesthetics are essential, and where insufficient enamel is available for etching.

Flowable: Flowable composite represents a relatively new subset of resin-based composite materials dating back to the mid-1990s. Compared with universal composites, flowable has a reduced filler content (37-53%) thus indicating ease of handling, lower viscosity, compressive strength, wear resistance and greater polymerisation shrinkage. Due to the worse mechanical properties, flowable composites should be used with caution in areas with high voltage. However, due to its beneficial wetting properties, it can adapt closely to the enamel and dentine surfaces. Indications include: restoration of small class I cavities, restoration of preventive resin (PRR), fissure sealant, liner cavity, poor amalgam margin improvement, and class V lesions (abfraction) caused by NCTSL. Contraindications include: in areas with high stress, recovery of large cavities on the surface, and if effective moisture control can not be achieved.

Packaged: Computable composites are developed for use in posterior situations. Unlike flowable composites, they exhibit higher viscosities and thus require greater strength in applications to 'pack' materials into prepared cavities. Their handling characteristics are more similar to dental amalgams, with greater strength required to condense the material into the cavity. Therefore, they can be considered 'colored amalgams of teeth'. Increased viscosity is achieved by higher filler content (& gt; 60% by volume) - thus making the material more rigid and more resistant to fracture, two properties ideal for materials to be used in the posterior area of ​​the mouth. The disadvantages of the associated increased filler content are the potential risks of cavity recognition along the cavity walls and between each layer of material. In order to cover any marginal deficiencies, the use of a single layer of flowable composite at the bottom of the cavity has been advisable when undertaking a Class II composite posterior restoration when using a packable composite.

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Indirect gear composite

The composites are not directly cured outside the mouth, in a processing unit capable of providing higher intensity and energy levels than handheld lights. Indirect composites can have higher fill rates, cured for longer periods and shrinkage preservation can be handled in a better way. As a result, they are less susceptible to shrinkage of stress and marginal gaps and have higher rates of healing and depth than direct composites. For example, the entire crown can be cured in one process cycle in an extra-oral preservation unit, compared to a millimeter filling layer.

As a result, full crowns and even bridges (replacing many teeth) can be made with this system.

Indirect gear composites can be used to:

• Filling cavities, as stuffing, inlay and/or onlay
• Fill the gaps between the teeth using a shell-like veneer or
• Teeth redevelopment
• Full or partial crown on a single tooth
• The bridge includes 2-3 teeth

Stronger, harder and more durable products are expected in principle. But in the case of inlay, not all long-term clinical studies detect these benefits in clinical practice (see below).

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Long life and clinical performance

Direct composite vs amalgam

Clinical survival of composite restorations is placed in the posterior tooth in the range of amalgam restorations, with some studies looking at survival times slightly lower or slightly higher than amalgam restorations. Improvements in composite technology and application techniques make composites an excellent alternative to amalgam, while use in large restorations and in cusp capping situations is debatable.

According to a 2012 review article by Demarco et al. which includes 34 relevant clinical studies, "90% of the studies show that the annual failure rate between 1% and 3% can be achieved with Class I and II posterior. [Back teeth] Composite restorations depend on the definition of failure, and on several factors such as tooth type and location, operator [dentist], and socioeconomic, demographic, and behavioral elements. "This compares to the 3% annual average failure rate reported in a 2004 review article by Manhart et al. for amalgam restorations in the posterior cushion-bearing cavity.

Demarco's review found that the main reasons mentioned for failure of posterior composite restorations were secondary caries (ie cavities developed after restoration), fractures, and patient behavior, particularly bruxism (grinding/packing.) The cause of amalgam restoration failure reported in Manhart review et al. also includes secondary caries, fractures (from amalgam and/or tooth), as well as cervical overlays and marginal hooking. The Demarco et al. review of composite restoration studies notes that patient factors affect longevity of restoration: Compared with patients with good dental health generally, patients with poor dental hygiene (probably due to poor dental hygiene, diet, genetics, frequency of dental checkup, etc..) experience a higher failure rate than composite restorations due to subsequent decay. Socioeconomic factors also play a role: "People who always live in the poorest stratus [ sic ] [stratum?] Of the population have more restoration failures than those who live in the richest layers."

The definition of failure applied in clinical studies may affect reported statistics. Demarco et al noted: "Failure of restorations or restorations that show minor damage is routinely handled by substitutions by most physicians.For this, over the years, replacement of damaged restorations has been reported as the most common treatment in general dental practice... "Demarco et al observed that when restored and repaired restorations were classified as failures in one study, the Annual Failure Rate was 1.9%. However, when restored restorations are reclassified as a success rather than a failure, AFR decreases to 0.7%. The reclassification of minor defects that can be corrected as a success and not a failure can be justified: "When the restoration is replaced, a large number of healthy tooth structure is removed and preparation [l.e. hole] is enlarged". Applying a narrower definition of failure will increase the longevity of reported composite restorations: Restoration composites can often be easily repaired or extended without drilling out and replacing the entire filling. The resin composite will be attached to the tooth and the previously undamaged composite material. In contrast, amalgam fillings are held in place by a form of emptiness filled not by adhesion. This means that it is often necessary to drill and replace all amalgam restorations rather than adding to the rest of the amalgam.

Direct and indirect Composite

It might be expected that more expensive indirect techniques lead to higher clinical performance, but this is not seen in all studies. An 11-year study reported similar failure rates from direct composite fillings and indirect composite inlays. Another study concluded that although there was a lower level of inlay composite inlay it would be insignificant and also too small to justify the additional effort of the indirect technique. Also in the case of ceramic inlays the survival rate is significantly higher than that of indirect composite charge can not be detected.

In general, the obvious advantage of colored tooth inlays over composite direct fillings can not be determined by the current review literature (in 2013).

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See also

• Dental restorations
• Dental bond

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References

Source of the article : Wikipedia