Does my tooth need to be refilled if a composite filling becomes discolored or stained?
The composite filling can become stained or become more yellow with time. When this happens, people often inquire about the need for their replacement; it is evident in discussion threads on online health forums and Q&A sites like this one here.
It is not always necessary to replace a discolored composite restoration. Usually, if I inspect a discolored or stained composite restoration, and it appears intact and well sealed, I will try to remove a tiny bit of the surface with a sandpaper disk or a fine diamond bur, to ascertain if the stain or yellow color is superficial. Often it is, and afterward, my patient no longer feels the need to replace their restoration.
Why does this surface staining or discoloration happen? Composite restorations are made partly of plastic resin and this resin can at least at the surface become porous and can either pick up stains or appear more yellow. Fortunately, this discoloration is often just on the surface and after removing a few microns of the composite, it appears "refreshed. Assuming that a tooth is still well filled, having its length of service extended is a good thing since more frequent refilling may make it more likely that the tooth will eventually require a crown or a root canal.
Patients can help themselves extend the life expectancy of their tooth-colored composite restorations by having excellent oral hygiene, since composite fillings that are kept clean tend to exhibit less staining and discoloration. Using your toothbrush and floss correctly will tend to keep these fillings looking good and maintain their proper color.
A stained restoration may need to be replaced due to decay. Still, if a restoration has stained and did not have decay, it may be polished or buffed with polishing discs to revitalize it. This will help the restoration to blend naturally with the tooth again and improve the overall aesthetics. Hence, it depends on from individual to individual as the shade of each restoration has to be tailored to suit the person's needs.
Another reason for replacing white fillings is after whitening. Here the teeth will brighten, but any composite will not change color. Therefore, they may need to be replaced to match in with the new shade.
White fillings can gather staining, particularly in the edges. This is usually treated by smoothing down the edges, but sometimes replacement is needed to get an acceptable result. Do note that white fillings may also change color over time. This is more likely with older materials. As things in the world, they undergo wear and tear.
Hope that provides you with some alternatives to consider when you notice your fillings become discolored over time.