How Long Do Dental Fillings Last?

Dental fillings do not last forever, but modern filling materials provide reliable service for many years. Composite fillings last 5 to 10 years, amalgam fillings last 10 to 15 years, and ceramic fillings (inlays and onlays) last 10 to 15 years or longer. A large-scale longitudinal study published in the Journal of Dental Research (2014) followed over 8,000 restorations and found that the median survival time for composite fillings was approximately 7.8 years, while amalgam fillings achieved approximately 12.8 years. However, individual filling lifespan varies significantly based on oral hygiene, bite forces, filling size, and the tooth’s position in the mouth.

At Townsville Dental Clinic, we monitor every filling at your six-monthly check-up and recommend replacement only when there is clinical evidence of failure — not on a fixed schedule.

Filling Materials and Their Lifespans

Composite Resin (Tooth-Coloured)

Average lifespan: 5 to 10 years
Material: BPA-free acrylic resin with glass or ceramic filler particles
Strengths: Tooth-coloured, bonds directly to tooth, preserves more natural structure, can be repaired
Limitations: Less durable than amalgam under heavy biting forces, can stain over time with coffee, tea, and red wine
Best for: Front teeth, small to moderate cavities on any tooth, patients who prefer a natural appearance

Composite is the most commonly placed filling material in Australian dental practices today. At Townsville Dental Clinic, composite fillings cost $150 to $350.

Amalgam (Silver)

Average lifespan: 10 to 15 years
Material: An alloy of silver, tin, copper, and mercury
Strengths: Extremely durable, cost-effective, long track record of clinical success
Limitations: Silver colour is visible, requires more tooth removal, contains mercury (though the Australian Dental Association confirms the amount is safe for most patients)
Best for: Large cavities on back teeth where strength is critical and visibility is low

Amalgam fillings are less commonly placed today due to aesthetic preferences, but they remain a safe and effective option.

Ceramic (Inlays and Onlays)

Average lifespan: 10 to 15+ years
Material: Porcelain or lithium disilicate fabricated in a dental laboratory or milled with CEREC
Strengths: Extremely durable, tooth-coloured, stain-resistant, biocompatible
Limitations: Higher cost, requires two appointments (unless CEREC), more brittle than amalgam
Best for: Large cavities on back teeth where both strength and aesthetics are desired

At Townsville Dental Clinic, ceramic inlays and onlays cost $900 to $1,500.

Glass Ionomer

Average lifespan: 3 to 5 years
Material: Acrylic and fluoroaluminosilicate glass powder
Strengths: Releases fluoride (helps prevent decay), bonds chemically to tooth, suitable for low-stress areas
Limitations: Weaker than composite and amalgam, shorter lifespan
Best for: Small fillings near the gum line, temporary restorations, paediatric fillings

Factors That Affect Filling Longevity

Factor	Effect on Lifespan
Bruxism (teeth grinding)	Significantly reduces lifespan — the strongest predictor of premature failure
Filling size	Larger fillings fail sooner — fillings covering >50% of the tooth surface are 2–3x more likely to fracture
Tooth location	Back teeth (molars) endure greater forces, reducing filling lifespan compared to front teeth
Oral hygiene	Poor hygiene allows secondary decay to develop at the filling margins
Diet	High sugar and acidic foods accelerate decay around the filling
Material	Amalgam outlasts composite on average; ceramic outlasts both in some studies
Dentist technique	Proper moisture control, bonding protocol, and marginal adaptation improve longevity

Signs Your Filling Needs Replacing

Watch for these warning signs and mention them at your next check-up:

Sensitivity — ongoing sensitivity to hot, cold, or sweet foods around a previously filled tooth may indicate the filling seal has broken down.
Visible damage — cracks, chips, or pieces missing from the filling surface.
Dark margins — a dark line around the edge of the filling suggests leakage and possible decay underneath.
Rough edges — a filling that feels rough, sharp, or catches your tongue has likely worn or chipped.
Pain on biting — pain when you bite down on the filled tooth can indicate a cracked filling or underlying decay.
Food trapping — if food consistently gets stuck around a filling that never had this problem, the filling margins may have opened up.

Your dentist checks every filling at your six-monthly examination using visual inspection, a dental explorer, and periodic X-rays to detect problems that may not yet be causing symptoms.