Mastering anterior direct composite restorations is a necessity for the contemporary clinician who appreciates and understands the art and science of cosmetic dentistry. In the esthetic zone, composite bonding procedures are considered the most conservative and least invasive technique to return missing, diseased, and unsightly tooth structure to enhanced color, form, and function. Composites’ attractiveness and popularity are easy to explain because these restorations have excellent esthetic potential, very good to excellent prognosis, and a reasonable fee. Composites are the most versatile restorative material available to the dental professional, especially for the esthetic-conscious patients. For composite restorations to mimic natural tooth structure, the clinician must have a comprehensive understanding of the material science and techniques involved in direct bonding procedures.
Mastering anterior direct composite restorations is a necessity for the contemporary clinician who appreciates and understands the art and science of cosmetic dentistry. In the esthetic zone, composite bonding procedures are considered the most conservative and least invasive technique to return missing, diseased, and unsightly tooth structure to enhanced color, form, and function. The attractiveness and popularity of composites are easy to explain because these restorations have excellent esthetic potential, very good to excellent prognosis, and a reasonable fee .
Composites are the most versatile restorative material available to the dental professional, especially for the esthetic-conscious patients. The restorative dentist can use this versatile material in a mirage of indications and techniques. It is used as a direct and indirect restorative material on anterior and posterior teeth, orthodontics attachments and bracket cement, indirect restoration cements, correction of erosive and abfraction lesions, bases, liners, core build-ups and post and cores, mock-up for anterior esthetic or posterior occlusal trial therapy, splinting, provisionalization, gingival stabilization, and so forth.
For composite restorations to mimic natural tooth structure, the clinician must have a comprehensive understanding of the material science and techniques involved in direct bonding procedures. Material science can be broken down to include types of composites, tints, opaquers, adhesive systems, and armamentarium. The necessary techniques involve an understanding of color, adhesive principles, layering to create polychromicity, incisal effects and perfect imperfections, and finishing and polishing.
Composite materials
Composition
A composite is a multiphase substance formed from a combination of materials that differ in composition or form, remain bonded together, and retain their identities and properties . They have four main components: (1) resin (organic polymer matrix); (2) filler (inorganic) particles; (3) coupling agent (silane); and (4) the initiator-accelerator of polymerization.
Resin matrix
Manufacturers prefer Bis-GMA resins because they have an aromatic structure that increases stiffness and compressive strength and lowers water absorption . Bis-GMA 2,2-bis [4(2-hydroxy-3 methacryloyloxy-propyloxy)-phenyl] propane is the most popular dimethacrylate resin, but to accommodate better filler load triethylene glycol dimethacrylate or urethane dimethacrylate is added .
Fillers
Filler (inorganic) particles provide dimensional stability to the soft resin matrix . The filler particles used in composites vary in size from less than 0.04 u to over 100 u. Common fillers are crystalline quartz; colloidal and pyrolytic silica; and such glasses as lithium, barium, or strontium silicate.
Coupling agent
Silane helps form a good bond between the resin matrix and filler particles during setting. The silane contains functional groups (eg, methoxy) that hydrolyze and react with the inorganic filler, and unsaturated organic groups that react with the resin matrix during polymerization .
Initiators and accelerators of polymerization
Composites contain initiators and accelerators that allow for light-, self-, and dual-cure modes. For visible light activation, camphoroquinones (0.03%–0.09%) start the free radical reaction using blue light in the 468 nm ± 20 nm range . In the esthetic zone, light-cured composites are the material of choice because color matching and color stability are the most predictable.
For chemical-cured composites, aromatic tertiary amine (2%) initiates the free radical reaction when the paste and catalyst are mixed. Tertiary amines (and HEMA found in many adhesive systems) have been found to cause color change in composites on polymerization .
Classification and application
Historically, composites have been classified by particle size, shape, and distribution of fillers . In the 1980s and 1990s, composite technology developed and became refined into two classifications: microhybrids and microfills. At the new millennium, nanotechnology introduced a new class of composite: the nanofillers. The three classifications of composites have their very distinct indications, advantages, and disadvantages ( Table 1 ).
