Composite fillings are directs, aesthetic fillings which cause minimal tooth tissue loss.
Apart from its superior aesthetic features composites bond to tooth chemically unlike amalgam which needs extra healthy tooth tissue removal for maintenance of enough retention. Another disadvantage of amalgam is tooth fracture or impairment due to metal expansion.
Composite resins are applied easily in one visit.
Treatment of chipped, broken or worn teeth is possible with composite resins.
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, tooth is prepared for impression. Inlay or onlay is fabricated on the model which is made from the impression. A return visit is then required to fit the final restoration.
What are the advantages of indirect restorations?
Although improvements of the composite filling pastes achieved during last few years, they can shrink a few percent in volume during hardening. This can disrupt marginal adaptation or cause gap with the adjacent teeth. In contrast, inlays and onlays have very fine line of contact at the tooth-to-restoration margin, perfect contact with the adjacent teeth and integrity with the gum. This way risk for recurrent decay is minimal, 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 abrade the teeth as well, unlike crown restorations.
When a decay or fracture is so extensive that a direct restoration such as amalgam or composite, would risk the structural integrity of the tooth or would be inadequate against to 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 not only very aesthetic but also wonderful option for restoring teeth that have suffered from extensive decay.