Dental composite resins also called as resin based composites are a type of dental cements made of synthetic resins. Synthetic resins evolved as restorative materials since they were insoluble, tooth-like appearance, insensitive to dehydration, easy to manipulate and inexpensive, and all these properties increased the use of dental composites in various dental procedures.
Uses of Dental Composites
Dental composites are used in various procedures, some of them are mentioned below
- Dental classI or classII restorations
- Dental onlays and inlays
- Aesthetic restorations in anterior teeth
- Dental veneers
- Dental crowns
- CAD-CAM crowns
- Implant crowns
- Sometimes as Core build-up material
- Pit and fissure sealants
The dental composite typically consists of a resin-based oligomer matrix, such as a bisphenol A-glycidyl methacrylate (BISGMA), urethane dimethacrylate (UDMA) or semi-crystalline polyceram (PEX), and an inorganic filler such as silicon dioxide (silica). Without a filler material the resin wear offs easily, exhibits high shrinkage and is exothermic. Compositions of composites vary widely, with proprietary mixes of resins forming the matrix, as well as engineered filler glasses and glass ceramics and these filler material gives the composite greater strength, wear resistance, decreased polymerization shrinkage, improved translucency, fluorescence and colour, and a reduced exothermic reaction on polymerization.
Advantages Of Composites
Tooth like appearance - The main advantage of a direct dental composite over traditional materials such as amalgam is aesthetic appeal of the restoration. Composites are available in a wide range of tooth colors allowing near invisible restoration of teeth. Composite fillings can be closely matched to the color of existing teeth color.
Bonding property - Composite fillings micro-mechanically bond to tooth structure and this strengthens the tooth’s structure and restores original physical integrity of the tooth. The discovery of acid etching i.e. producing enamel irregularities ranging from 5-30 micrometers in depth of teeth to allow a micro mechanical bond to the tooth allows good adhesion of the restoration to the tooth structure. Very high bond strengths to tooth structure, both enamel and dentin, can be achieved by using dentin bonding agents.
Cost-effective - In some situations, a composite restoration may be offered as a less-expensive alternative to a dental crown, on the other hand which can be a very expensive treatment.
Alternative to tooth extraction - As a composite restoration bonds to the tooth and can restore the original physical integrity of a damaged tooth, in few cases composite restoration can restore a tooth that might not be salvageable with amalgam restoration, for example, depending on the location and extent of decay, it might not be possible to create a void of the geometry necessary to retain an amalgam filling.
Repairability property - Most of the time in cases of minor damage to a composite filling, the damage can be easily repaired by adding some additional composite. On the other hand an amalgam filling might require complete replacement.
Less working time - As the composites are light-cured it allows on-demand setting, and it also doesn’t need any mechanical manipulation as in case of amalgam.
Reduced mercury exposure - As composites don’t contain mercury, there is no problem of mercury poisoning and no side effects of mercury vapors.
Lack of corrosion - This property of composite makes it very feasible to use in many types to dental treatments.
Disadvantages of Composites
Shrinkage and secondary caries - This is one of the disadvantage of composites where microhybrid and nanohybrid composites have a polymerization shrinkage that ranges from 2% to 3.5%. This microleakage can lead to secondary caries if not detected early. Composite shrinkage can be reduced by altering the molecular and bulk composition of the resin which can help in preventing microleakage.
Durability property - In some situations, composite fillings may not last as long as amalgam fillings under the pressure of masticatory forces, particularly if used for large cavities.
Chipping off - Composite materials can chip off the tooth, but it can be treated without removing the entire restoration.
Skill and training required - Successful outcomes in direct composite fillings is related to the skills of the practitioner and technique of placement of the filling. For example, a rubber dam is rated as being important for achieving longevity and low fracture rates similar to amalgam in the more demanding proximal Class II cavities so, the practitioner should be well trained.