Dental onlays typically last 10 to 15 years, though the full range spans 5 to 30 years depending on the material used, your bite habits, and how well you care for them. At the 10-year mark, clinical studies show survival rates above 90% for both ceramic and gold onlays, meaning the vast majority are still functioning well a decade after placement.
Survival Rates by Material
The three main onlay materials are ceramic (including porcelain), gold, and composite resin. Each performs differently over time, and the differences become more apparent the longer you have the restoration.
Ceramic onlays have the strongest long-term track record in recent research. A retrospective study published in Clinical Oral Investigations found that ceramic onlays had a cumulative survival rate of 93.9% after about 15 years, dropping only slightly to 91.7% at 23.5 years. Their annual failure rate was just 0.5%. The most common reason ceramic onlays fail is fracture of the ceramic itself, which occurred in about 6.7% of cases over the full study period.
Gold onlays, long considered the gold standard, performed similarly. The same study found gold partial crowns survived at a rate of 92.6% after about 15 years and 91.8% after 23.5 years, with an annual failure rate of 0.7%. Gold rarely fractures, but it’s more prone to complications with the underlying tooth. Endodontic problems (issues with the tooth’s nerve) occurred in 8.8% of gold restorations, compared to just 2.7% for ceramic. Both materials had nearly identical rates of decay forming underneath, at around 4.7% to 4.8%.
Composite resin onlays are the least durable of the three. A prospective study in the European Journal of Dentistry reported an 85% success rate at 9 years. That’s a meaningful drop compared to ceramic and gold at similar time points. Composite does offer some advantages: it’s easier to repair, distributes stress more naturally, and costs less. But if longevity is your priority, ceramic or gold will serve you better.
How Onlays Compare to Crowns
Full crowns generally last a bit longer than onlays, typically 15 to 20 years compared to 10 to 15 for onlays. That makes sense because a crown wraps completely around the tooth, offering more protection. But crowns also require removing significantly more healthy tooth structure. An onlay preserves more of your natural tooth, which matters because that healthy structure can never be replaced. For teeth with moderate damage that don’t need full coverage, an onlay strikes a practical balance between durability and conservation.
What Makes Onlays Fail
Onlays don’t just fall out one day. They tend to fail gradually, and the failure mode depends on the material. Ceramic onlays most often fail by cracking or chipping. Gold onlays are more likely to lose their bond to the tooth or develop problems with the nerve underneath. For all materials, decay forming at the margins (the edges where the onlay meets your tooth) is a consistent risk over time.
Several signs suggest your onlay may be failing. Increased sensitivity to hot and cold is one of the earliest warnings, especially if it develops years after placement. This often means the seal between the onlay and your tooth has broken down, exposing nerve endings. Difficulty biting or chewing, a feeling that the onlay is loose or shifting, or visible cracks in the restoration are all reasons to get it checked promptly. Catching a failing onlay early often means a simpler replacement. Ignoring it can lead to decay spreading deep into the tooth.
Teeth Grinding and Onlay Survival
If you grind your teeth at night, you might assume onlays won’t hold up. The data is more encouraging than you’d expect. A 14-year study in The Journal of Prosthetic Dentistry tracked lithium disilicate (a type of pressed ceramic) restorations specifically in patients with severe tooth wear, many of whom had bruxism. The overall yearly failure rate was just 0.1%, and the researchers found that clinical variables like grinding did not significantly affect survival. Modern ceramic materials are strong enough to withstand heavy bite forces when the restoration is designed properly.
That said, if you know you grind, wearing a night guard is still wise. It protects not just the onlay but all your teeth from excessive wear. Your dentist can fit one that accommodates the restoration.
How to Make Your Onlay Last Longer
The basics matter more than anything exotic. Brushing twice daily and flossing around the onlay keeps bacteria from building up at the margins where the restoration meets your tooth. That margin is the weak point. Once bacteria get underneath, decay can spread without you seeing it, and by the time you notice symptoms, the damage may require a crown or more extensive work.
Regular dental checkups let your dentist catch small problems before they become big ones. They can spot early signs of marginal breakdown, minor chips, or beginning decay that you’d never feel or see on your own. Avoiding habits like chewing ice, biting pen caps, or opening packaging with your teeth protects onlays from the kind of sudden impact forces that cause fractures. These habits are hard on all teeth, but particularly risky for restorations.
The quality of the initial placement also plays a major role, and it’s the one factor you influence by choosing your dentist carefully. A well-fitting onlay with tight margins and proper bite adjustment starts its life with every advantage. A poorly fitting one may technically last for years but develop hidden decay underneath long before it visibly fails.