|Year : 2022 | Volume
| Issue : 1 | Page : 3-7
Recent advancements in materials in pediatric restorative dentistry
Chaitali Hambire1, Umesh Hambire2
1 Department of Pediatric Dentistry, Government Dental College and Hospital, Aurangabad, Maharashtra, India
2 Department of Mechanical Engineering, GECA, Aurangabad, Maharashtra, India
|Date of Submission||14-Sep-2021|
|Date of Decision||04-Apr-2022|
|Date of Acceptance||04-Apr-2022|
|Date of Web Publication||16-Jul-2022|
Dr. Chaitali Hambire
17, Shreekunj, Samadhan Colony, Behind Sessions Court, Aurangabad 431 001, Maharashtra
Source of Support: None, Conflict of Interest: None
The most common infectious disease affecting the children worldwide is dental caries. It affects children of all races, castes, and creeds. Refined diet and improper oral hygiene increase the risk of caries in children. Meticulous clinical examination and diagnosis of dental caries are an integral part of a comprehensive treatment plan. The factors to be considered include the developmental status of the dentition, caries-risk assessment, the patient's oral hygiene, anticipated parental compliance and likelihood of timely recall, and the child's ability to cooperate for treatment. Restorative science is undergoing great revolutions that are leading the humanity toward a new era of dentistry.
Keywords: Composite, dental caries, glass ionomer cement, nanotechnology, pediatric dentistry
|How to cite this article:|
Hambire C, Hambire U. Recent advancements in materials in pediatric restorative dentistry. Int J Oral Health Sci 2022;12:3-7
| Introduction|| |
The most important aim in pediatric dentistry is to provide the best dental care to the patients which can be attained with the help of a skilled pedodontist and its team. The lack of motor dexterity, refined diet, improper oral hygiene, and specific teeth morphology contribute to increased incidence of dental caries in pediatric population. Dental restorative materials are designed as per their intended purpose. Research is continuously ongoing toward the development of materials in restorative dentistry for providing better services to the patients. With the increase in awareness and adverse effects of mercury on the environment, alternative filling materials to dental amalgam have become increasingly favored.
| Restorative Materials in Pediatric Dentistry|| |
Glass ionomer cement (GIC) is restorative materials which are made up of calcium, strontium aluminosilicate glass powder (base) combined with a water-soluble polymer (acid). When the components are mixed together, they undergo a setting reaction involving neutralization of the acid groups by the powdered solid glass base.
By bonding a restorative material to tooth structure, the cavity is theoretically sealed, protecting the pulp, eliminating secondary caries, and preventing leakage at the margins.
Margin adaptation and leakage
The coefficient of thermal expansion of conventional GIC is close to that of dental hard tissues and has been cited as a significant reason for the good marginal adaptation of glass ionomer restorations.
Fluoride is released from the glass powder at the time of mixing and lies free within the matrix. It can, therefore, be released without affecting the physical properties of the cement.
Conventional GIC is tooth colored and available in different shades.
The biocompatibility cement is very important because they need to be in direct contact with enamel and dentin if any chemical adhesion is to occur.
Color and translucency
Both conventional and resin-modified GIC are available in various shades and provide acceptable color matching and translucency
Conventional GIC is radiolucent, but resin-modified and lining GIC are radiopaque due to the presence of lanthanum, barium, or strontium in the powder.
Strength and fracture resistance
The compressive strength is similar to that of zinc phosphate cement, and its diametral strength is slightly higher. The modulus of elasticity of GIC ranges from 7 Gpa to 13 Gpa.
GIC has less resistance to abrasion than composite resins, but abrasion resistance improves as the cement matures.
Solubility and disintegration
Properly set GIC exhibits low solubility in the oral environment. In patients with xerostomia, the use of conventional GIC should be avoided as the cement will undergo rapid disintegration.
| Recent Advancements in Glass Ionomer Cement|| |
In this modification, the liquid is delivered in a freeze-dried form that is then incorporated into the powder. The liquid to be used is clean water only, and this may enhance shelf-life and facilitate mixing.
Resin-modified glass ionomer
They were introduced in 1988 by Antonucci et al. to overcome the problems associated with the conventional glass ionomers and at the same time preserving the clinical advantage of conventional materials. They are a hybrid of glass ionomer and resin composites. A dimethyl methacrylate monomer, HEMA is grafted in polyacrylic acid. With the exposure of light, polymerization is initiated along with the methacrylate groups; after that, the aci d–base reaction is carried out. It has been seen in several reports that the rate of fluoride release by resin-modified glass ionomers (RMGIs) is similar to that of conventional GI. However, this release is influenced by the formation of complex fluoride derivatives with their reaction with polyacrylic acid, accompanied by the type and amount of the resin used in the light polymerization. Release of fluoride from various RMGIs during the first 24 h is maximum with 5–35 μg/cm2 depending on the storage environment.
The nano-ionomer delivers greater wear resistance, esthetics, and polish compared to other glass ionomers, while offering fluoride releases similar to conventional and RMGIs.
According to Mclean and Nicholson, compomers can be defined as: “materials that may contain either or both of essential components of a GIC but at levels insufficient to carry out the acid curing reaction in the dark.” Hence, photoactivation is absolutely necessary for this type of material. It is formed by the combination of composites and glass ionomers (Compomer). They contain dimethacrylate monomer and two carboxylic groups along with ion-leachable glass and the absence of water in the composition. The glass particles are fillers and are partially silanated to ensure bonding with the matrix. When compared with RMGI cement (RMGIC), they have a limited dual set mechanism. The dominant setting reaction is the resin photopolymerization and no acid–base can occur until later when the material absorbs water. Like GIC, they also release some fluoride ions.
Ceramic-reinforced glass ionomer
Ceramic-reinforced posterior GIC features are stronger.
Condensable/self-hardening glass ionomer cement
It was developed in 1990s as filling material for ART. These are purely chemically activated RMGICs with no light activation at all. It is used mainly in pediatric dentistry for the cementation of stainless steel crowns, space maintainers, bands, and brackets. It has high viscosity. High viscosity is due to the addition of polyacrylic acid to the powder and fine grain size distribution: composition: powder: aluminosilicate glass – 90%–95%, polyacrylic acid – 3%–5%, liquid: polyacrylic acid – 45%, and distilled water – 50%. It is indicated in Class I and Class II in primary teeth, geriatric restorative in Class I, II, III, V, long-term temporaries in rampant caries, Class I and Class II in permanent teeth in nonstress bearing areas, core build-up, and deep pit and fissure restoration. It has the advantages of being packable/condensable, easy placement, nonsticky, reduced early moisture sensitivity, rapid finishing, improved wear resistance, and low solubility in oral fluids.
The low viscosity/flowable glass ionomer cement
It is a fluoride recharge material. To overcome the shortcomings faced by fluoride releasing material, a new material has been developed for fluoride release. Greater the fluoride release in a material, more open is the structure resulting in low strength. To improve the strength of these fluoride-containing materials, if they are made more dense and strong, then the efficacy of F release is decreased. Soon after placement, there is a sudden burst of fluoride release, followed by a rapid decline in ion release rate. This modified GIC has two parts: the restorative part and charge part, the restorative part is used the usual way when the 1st burst of fluoride is expelled, the therapeutic potential of the restoration is spent. The material is given a second fluoride charge using a gel material-charge part that replenishes the fluoride site in the restoration by ion exchange and recovers the fluoride release and therapeutic potential of the restoration. This is achieved without replacing the material. It is used as pit and fissure sealant, lining, endodontic sealers, and sealing of hypersensitive cervical areas. Examples of commercially available materials are Fuji Lining LC, Fuji III and IV, and Ketac-Endo.
This is a combination of glass ionomers and composite and is a new type of restorative material properties: fluoride release and recharge, excellent esthetics, and polishability and biocompatibility. Giomers are resin-based and contain prereacted glass-ionomer (PRG) particles. The particles are made up of fluorosilicate glass which reacts with polyacrylic acid before incorporation into the resin. The prereaction can involve only the glass particles surface (known as surface PRG ionomer or S-PRG) or the entire particle (termed fully PRG ionomer or F-PRG). Giomers are similar to compomers and resin composites in being highly activated and requiring the use of a bonding agent to adhere to the tooth structure. Giomers release fluoride but do not have the initial “burst” type of fluoride release, and long-term release (i. e., 28 days) was lower than GIC, RMGIC, and compomer. On polishing with soflex discs, they have a smoother surface than GIC, commercially available giomers – Beautiful shofu.
| Dental Composites|| |
To improve the physical characteristics of unfilled acrylic resins, Bowen of the National Bureau of Standards developed a polymeric dental restorative material reinforced with silica particles. The introduction of this filled resin material in 1962 became the basis for the restorations that are generically termed composites. Composites are presently the most popular tooth-colored materials, having completely replaced silicate cement and acrylic resin.
It is also known as condensable composites. It is composed of resin matrix and an inorganic ceramic component. Rather than including the filler particles into the composite resin matrix, resin is incorporated into the fibrous ceramic filler network; the filler consists of aluminum oxide, silicon oxide glass particles, or barium aluminum silicate or strontium glasses. These were developed in a direct effort to produce a composite with handling characteristics similar to amalgam, therefore, the name “packable” or “condensable.” It is intended primarily for Class I and Class II restorations. Distinguishing characteristics of packable composites are that they are less sticky and possess higher viscosity when compared to traditional hybrid composites that allow them to be “packed” in a manner that somewhat resembles amalgam placement. As there is increased viscosity and resistance to packing, some lateral displacement of the matrix band is possible. Their development is an attempt to accomplish two goals: easier restoration of a proximal contact and similarity to the handling properties of amalgam. They do not completely accomplish either.
Flowable composites have low viscosity which possesses particle size and its distribution similar to that of hybrid composites but with reduced filler content which decreases the viscosity of the mixture as the amount of resin increases. Since this composite was developed with specific handling characteristics in mind, their range of clinical uses is quite varied. Mechanical properties are inferior to those of standard hybrid composites, inferior physical properties, low wear resistance, low strength, low resistance to fracture, and lower filler content. Popular features are easy to use, favorable wettability, and handling properties. They are indicated in small Class I restorations, as pit and fissure sealants, marginal repair materials, and as a first increment placed as a liner under hybrid or packable composites. Flowable composites are essentially “thinned down” composites with fewer filler particles into the resin. Baoudi K et al. (2015) suggested in a systematic review that the flowable composites are the promising esthetic restorative materials for the future and will become markedly useful materials in various esthetic restorative procedures.
It is an indirect composite material and is commercially available as Targis. It is a combination of ceramic optimized polymers (ceromers) and a fiber-reinforced composite framework material. Ceromers combine the advantages of ceramics with those of state-of-the-art composites. Ceromers are composed of specially developed and conditioned five-particle ceramic fillers of submicron size (0.04 and 1.0 mm) which are closely packed (approximately 85 wt percent) and embedded in an advanced temperable organic polymer matrix. Ceromers combine the advantages of ceramics and composites: durable esthetics quality, abrasion resistance, high stability, ease of final adjustment, excellent polishability, effective bond with luting composite, low degree of brittleness, susceptibility to fracture, and possibility of repairing restorations in the mouth. In addition to being esthetic, ceromer restorations also conserve tooth structure. Furthermore, adhesive cementation with advanced luting composites assures the stability of these restorations.
Ormocres are organically modified ceramics. It was developed by Fraunhofer Institute for Silicate Research. Ormocers were introduced as a dental restorative for the first time in 1998. These materials are also used in electronics, microsystem technology, refinement of plastics, conservation and corrosion coatings, functional coatings of glass, and anti-scratch protective coatings. Ormocers have inorganic as well as an organic networks. Ormocers consist of three components – organic, inorganic portions, and polysiloxanes. The proportions of these components can affect the mechanical, thermal, and optical qualities of the material. The inorganic components are bound to the organic polymers by multifunctional coupling agent silane molecules. After polymerization, the organic portion of the methacrylate groups forms a three-dimensional network. It has advantages of better marginal seal. The large size of monomer molecule minimizes polymerization shrinkage.
It consists of fiber material held together by resinous matrix. They are structural materials that have at least two district constituents – the reinforcing component which provides strength and stiffness and the surrounding matrix supports the reinforcements and provides workability. In dental applications, polymeric or resin matrices reinforced with glass, polyethylene, or carbon fibers are most common. It bears good overall mechanical properties with superior strength. It has noncorrosive properties. It has potential translucency along with radiolucency. It has good bonding properties as well as good flexural strength.
Nanotechnology is applicable in manufacturing of advanced dental materials. Nanotechnology is also known as molecular engineering or nanotechnology. It involves the production of functional materials and structures within the range of 0.1–100 nm by various physical or chemical methods. The use of nanomaterials stems from the idea that they may be used to manipulate the structure of materials which provide dramatic improvements in chemical, electrical, mechanical, and optical properties. Nanofillers and nanocomposites have been developed using advanced methacrylate resins and curing technologies. There are two new types of nanofiller particles: nanomeric or NM particles and nanoclusters. Nanomeric involves monodisperse nonaggregated and nonagglomerated silica nanoparticles. For synthesis of dry powders of nanosized silica particles, 20 and 75 nm in diameter, aqueous colloidal silica sols were used. The dental nanocomposite system shows high translucency, high polish, and polish retention which is similar to that of microfills while maintaining physical properties and resistance equivalent to those of several hybrid composites. The strength and esthetic properties allow to use the resin-based nanocomposite for both anterior and posterior restorations. It has advantages of improved mechanical characteristics, good thermal stability, corrosion resistance, increased transulency, and improved handling properties.
Introduction of agents such as silver or one or more antibiotics into the material and antimicrobial properties of composites may be accomplished. Silver and titanium particles were added to introduce the antimicrobial properties which enhance the biocompatibility of the composites. The antibacterial properties were based on contact mechanism instead of leaching which lasted for at least 1 month.
Stimuli-responsive materials possess properties that may be considerably changed in a controlled fashion by external stimuli. These stimuli can be temperature change, mechanical stress, pH, moisture, or electric or magnetic fields. These composites are used for treating the secondary caries in the posterior teeth region and have proven to be very effective.
Due to different physical, chemical, and biological stimuli, materials usually have a limited lifetime and get degrade which include external static (creep) or dynamic (fatigue) forces, internal stress states, corrosion, dissolution, erosion, or biodegradation. This ultimately leads to deterioration of the material structure and finally failure of the material. Epoxy resin composite was one of the first self-repairing or self-healing synthetic materials which shows some similarities to resin-based dental material. If a crack occurs in the epoxy composite material, some of the microcapsules are destroyed near the crack and release the resin. The cracks were filed by resin and reacted with a Grubbs catalyst dispersed in the epoxy composite, which results in polymerization of the resin and repair of the crack.
| Conclusion|| |
With emerging technologies and research in the field of dental materials, it is possible that 1 day we can have a restorative material that will biomimic the tooth structure that it restores. Among the variety of restorative materials available, it is advisable to choose the material that best suits the need of the pediatric patient.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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