A composite is a material formed by combining two or more components with different properties. Dental composite resins contain inorganic filler particles such as glass, quartz or silicon dioxide within a resin-based matrix. The material's properties depend on the composition and proportions of these components.
Because it is manufactured in shades close to tooth colour, composite is also called a tooth-coloured filling. Early use was mainly associated with front teeth, but material development has enabled its use in back teeth too. The decision depends on cavity size, remaining tooth tissue, chewing forces and the ability to control moisture during placement.
Metal or Composite Fillings?
Composite fillings may be preferred in many situations because of their tooth-coloured appearance and ability to bond to tooth tissue. However, no single material is suitable for every filling; selection depends on clinical requirements.
Composite properties have improved over time, and these materials can be used in posterior teeth in suitable cases. Durability does not depend solely on the material's name. Filling size, remaining tooth tissue, bite forces and technique affect the outcome. It therefore cannot be claimed that every composite filling is as durable as every metal filling.
Alongside their aesthetic properties, composites can bond to tooth tissue using adhesive systems. With materials such as amalgam, the cavity may need a specific shape to provide retention. With composite, decay and weakened tissue are removed, and retention is obtained through appropriate surface preparation and bonding systems. This allows more conservative preparation in some cases. Nevertheless, not every cavity can be filled without additional shaping; unsupported enamel and remaining walls must be assessed. Removing less tissue alone does not guarantee a longer-lasting filling. Correct placement and regular oral care are also important.
Filling materials may undergo different dimensional changes as they set. Composites can undergo polymerisation shrinkage, creating stress at the tooth–filling interface. Application technique, layering and light-curing conditions are therefore important. Cracking or fracture cannot be explained solely by filling type; cavity size and chewing forces also require assessment.
For composite placement, the tooth surface is prepared as required by the bonding system. The adhesive and composite are cured with suitable light to establish a bond. Surface preparation and moisture control are important for marginal adaptation. However, an absence of long-term leakage or recurrent decay cannot be guaranteed. Amalgam and other restorations can also develop marginal deterioration or new decay. The integrity of fillings and surrounding tooth tissue is assessed at regular reviews.
With light-cured composites, the dentist can shape the material within its appropriate working time. Incisal edges of front teeth and the contours of chewing surfaces of back teeth can be formed this way. Metal fillings have different working and setting properties. Whatever the material, tooth anatomy, contacts with adjacent teeth and the bite must be arranged correctly. Good appearance and function depend on placement and checks as well as material type.
Amalgam fillings and surrounding tooth tissue can develop a dark appearance over time. This requires clinical assessment of the filling.
Whether a damaged filling can be repaired depends on the extent of damage and surrounding tissues. Composite may be added under suitable conditions, while in other cases the filling needs replacement. The decision follows examination.
Composite fillings are one option suitable in many situations, but they are not the only option. Replacing a healthy, problem-free filling solely to use a different material is not automatically necessary.