A filling can be lost due to:
Decay around or underneath the filling.
This causes the supporting walls of tooth structure around the filling to be destroyed or the decay process destroys the bond of the filling material to the tooth.
An excessive force which breaks the filling material.
Patients who grind their teeth in their sleep (bruxism) or bite down into hard objects (bones, ice, shellfish, grit, beer bottle caps etc) can break fillings.
Wear of the filling material.
Patients who grind their teeth tend to quickly wear down both filling and the tooth structure surrounding the filling. When the filling material is so thinned down by this process, it loses material strength and eventually breaks.
This natural ageing process is true for all fillings (even in patients who do not grind their teeth) so eventually, a filling will need replacement.
Failure of the bonding procedure.
If a white/tooth-coloured filling material has been used, specific steps need to be followed to ensure a successful adhesion of the filling material to the tooth. Contamination with liquid (water, blood, saliva or oil) or insufficient cleaning of the tooth surface can cause early loss of the filling or tooth sensitivity.
Bonding to dentine (the inner moist living dental tissue) is usually not as long-lasting as bonding to enamel because all bonding agents degrade in the wet environment found in dentine. As much as 50% of dentine bond strength is lost after one year.
