One of the more common questions I'm asked is "which type of filling should I get, silver or white?" This is actually a complex question. When making this decision, we have to consider several vastly different factors- everything from the patient's personal preference, budget, esthetic demands of the tooth requiring the filling, accessibility of the decayed area, that sort of thing.
First- some basics; there are two main categories of fillings used to restore simple cavities: amalgam alloys (silver) and composite resins (white). Amalgam alloys are the silver fillings that many people are familiar with. They are dispensed from a self-contained capsule containing both liquid mercury and powdered metals such as silver, copper and tin. When mixed, the resulting compound is a stable alloy of all these metals- chemically connected to each other in a complex structure that is conveniently biocompatible. This allows use to use this alloy to rebuild broken teeth. The chemistry behind white fillings, or composites, is very different. Composites typically consist of a synthetic polymer resin that can be applied to a prepared tooth surface. Usually light-activated, they come in a variety of shades. The properties of white fillings have improved dramatically over the last 20 years, making a modern composite suitable for restoring front and back teeth alike.
Generally speaking, I do not feel one material is inherently "better" than the other. Saying so is like insisting that nails are better than screws, or vice versa. Both amalgam fillings and composite fillings can serve very similar functions, but are placed in very different ways. and each have unique advantages and disadvantages. In certain situations, it's useful to have both available. This blog post is to help the layperson understand why we might choose one over the other.
Safety and Efficacy
A quick note: in my opinion, which reflects the opinion generally accepted by the American Dental Association and dental schools across the country, both alloy and composite materials are perfectly safe to use. Both perform well when placed properly and used appropriately. I base my opinion on both the academic research I have been exposed to, as well as my years of experience as both a patient and a doctor. I use both types of materials routinely to treat my patients and family members alike. I do so with confidence knowing that in the thousands of years humans have been trying to fix teeth, these materials are now safer and more predictable than they ever have been. Like all therapies and medicines, research is ongoing to determine whether or not there are health risks to using these types of materials in the body. In my opinion, at this point all of the numerous benefits of using modern dental materials outweigh the hypothesized risks. I move forward impressing to you that I feel confident recommending both types to most patients.
So, if you need a filling, which type should you get? Amalgam or composite? Silver or white?
The first and most basic thing we consider is esthetics; no matter how functional, most folks would not be happy with a silver filling in a visible area of the mouth. So as a general rule, any restoration done that would be visible when smiling should likely be a tooth-colored composite. Of course, esthetic demands are different across cultures; many Greeks in my own culture find gold restorations and crowns in the smiling zone to be classy, so even this rule isn't hard and fast. But generally speaking, if esthetics are a concern, go with the composite.
The second thing we would consider is bond strength- composite restorations chemically bond themselves to tooth structure. This "glue" like property may strengthen a tooth to some extent, or at the very least, make the filling less likely to be lost entirely. Alloy restorations do not bond to the tooth- they are packed into a tooth as a sand-like mixture that must be quickly applied to a prepared tooth surface. After about five minutes of hardening, the silver filling will lock itself into the shape the dentist prepared and stay put. So, depending on whether or not we need the filling to glue itself to the tooth, or whether or not we are able to prepared the tooth in such a way that the alloy locks itself into place, this greatly influences our material choice.
Another key factor is access to the area that needs to be restored- an area that is very difficult to see and keep dry throughout the dental procedure is very difficult to restore with white filling materials. As previously mentioned, composites are able to bond to the tooth. However, this requires several steps that can be contaminated by a single drop of saliva. So, general speaking, if we are working in an area just underneath the edge of the gums, or underneath a crown next to the tongue, or any area that is difficult to isolate, using a bonded filling may be impossible. Alloy fillings are much more forgiving- while "clean and dry" is considered ideal when we are placing these fillings, a little moisture is unlikely to cause massive material failure the same way it would with a composite.
Finally, for most patients their budget and insurance coverage is a factor. Generally speaking, white composite restorations have a high material cost and are more time-intensive to place than amalgam alloy fillings. As a result, they can be more expensive and/or covered to a lesser extent by insurance companies. This can be a major factor if we are looking to restore several teeth in a patient- the price difference multiplied out over several different teeth can become very significant. So, all things being equal, if expense is a major concern for a patient and our other factors make either filling acceptable, amalgam may be the more economical choice. This can be drastically different across insurance companies, though; certain ones do not cover alloy fillings at all, whereas others will refuse to pay for white fillings on back teeth.
So, to recap: I feel very strongly that both amalgam (silver) and composite (white) fillings can be placed safely. There are both functional advantages and limitations to each material, which should be considered before you decide on one type of material or the other. If you have a strong preference, please be sure to let your dentist know. In most situations, we will be able to customize your treatment plan to what you think works best for you, I am always happy to explain my decision making process to a patient and I think most dentists will do the same; this lets you play an active role in your own treatment. Advocate for yourself, make an educated decision and let your preference be known!
Jason Coliadis DDS