Composite fillings are directs, aesthetic fillings which cause minimal tooth tissue loss.
Apart from their superior aesthetic features, composites bond to teeth chemically, unlike amalgam, which needs extra healthy tooth tissue removal to maintain enough retention. Another disadvantage of amalgam is tooth fracture or impairment due to metal expansion.
Composite resins are applied easily in one visit.
Composite resins can treat chipped, broken, or worn teeth.
Amalgam fillings contain mercury which is a toxic material for both human and environment. Its usage is restricted in many countries.
Inlays and onlays are highly aesthetic fillings that are fabricated in a dental laboratory. They are made of mostly porcelain or reinforced composite.
After removal of old restoration or decay or fractured part, the tooth is prepared for impression. Inlay or onlay is fabricated on the model, made from the impression. A return visit is then required to fit the final restoration.
Although composite filling pastes have been improved during the last few years, they can shrink a few percent in volume during hardening. This can disrupt marginal adaptation or cause gaps in the adjacent teeth. In contrast, inlays and onlays have a very fine line of contact at the tooth-to-restoration margin, perfect contact with the adjacent teeth, and integrity with the gum. This way, the risk for recurrent decay is minimal, and gum is healthier.
Composite fillings may wear off in time, or the margins may become colored. Porcelain fillings (inlay or onlay) exclude this problem. They do not irritate the teeth as well, unlike crown restorations.
When decay or fracture is so extensive that a direct restoration, such as amalgam or composite, would risk the tooth's structural integrity or would be inadequate against biting forces, an onlay might be indicated. Its advantage to a crown is the minimal removal of the tooth to prepare for impression.
Indirect fillings are aesthetic and beautiful options for restoring teeth that have suffered from extensive decay.