Factors contributing to the life of your dental fillings
Often, when a tooth is physically damaged from decay or trauma, dental fillings are used to replace lost structure.
As dentists, we try maximise the lifespan of all dental fillings by using the best materials placed under ideal working conditions. However, everything in dentistry has a finite lifespan and fillings are no different. A commonly asked question is: How long we can expect the filling to last? The answer is complex as each cavity and each filling is unique and there are many factors to consider.
Materials
Today, dental fillings can be made from one of two main types of material: porcelain and a soft plastic. Each type of filling has a slightly different lifespan due to inherent differences in the materials’ properties.
Porcelain fillings, or CEREC Porcelain fillings, are customised restorations shaped according to a 3D scan of the tooth cavity. They are milled chair-side from a high-strength, aesthetically appealing porcelain block. In my opinion, porcelain is the best filling material for medium or large cavities.
Porcelain dental fillings are generally considered the “definitive fix” for the tooth, and research has shown that they do very well over long periods of time – with success rates of at least 95 per cent after 10 years.[1]
Composite fillings, on the other hand, are made from a soft plastic material which is adapted to the tooth cavity and set hard with a blue light. These plastic fillings are generally weaker and not dimensionally stable over time. As a result, they have a relatively short lifespan – generally three to five years, depending on the size of the filling.
Placement
The way both porcelain dental fillings and composite fillings are placed can have a big impact on their longevity, and there are several things dentists can do to maximise their lifespan. In dentistry we have a saying, “The seal is the deal.” In other words, dental fillings are only as good as the quality of the bond between the tooth and the filling material. It therefore makes sense that anything that will help make a stronger bond will ultimately increase the lifespan of the filling.
All dental materials that rely on bonding to tooth structure (both CEREC and plastic fillings) are sensitive to moisture and won’t stick well if there is humidity or moisture (water or saliva) in the area. Hence, all dental fillings should ideally be done under rubber dam protection. The dam is a thin rubber sheet that protects the filling from contamination by moisture – much like a raincoat for the tooth. Rubber dam protection is mandatory when performing root canal treatment; and given how well it works, it should be the standard of practice for routine dental fillings as well.
Patient factors
There are also things patients can do to ensure they get the most out of their dental fillings. Any filling placed in the mouth is under stress – from daily eating and drinking, from the temperature changes of these foods and drinks, and from para-functional habits such as grinding or clenching of the teeth.
If the filling is needed due to decay, it is important for us to make sure we minimise the risk of developing new decay lesions in the future and thus avoid a need for early replacement of the dental filling. This may involve changing certain habits and incorporating more protective factors in the home care routine. Your decay risk profile and best ways to prolong the life of your dental filling will be discussed at your appointment.
[1] Posselt A, Kerschbaum T, “Longevity of 2328 chairside CEREC inlays and onlays”, International Journal of Computerized Dentistry, 6: 231–248.
