Composite vs. amalgam dental fillings.
Composite (bonded) and amalgam fillings each have their own unique set of characteristics that offer distinct advantages and disadvantages.
Since in every case each person's specific situation and needs will vary, it is only appropriate that their dentist is the one who addresses their concerns associated with the use of each of these types of fillings. We do however list many of the advantages and disadvantages of both of these types of restorations here so to help you formulate your questions for your dentist.
1) Advantages of bonded fillings as compared to dental amalgam.
A) Composite fillings blend in with your teeth.
There is no question that the tooth-colored appearance of composite fillings is more cosmetically pleasing than the silver coloration of dental amalgam fillings. And in those cases where the use of either restorative is appropriate it is easy to see why a dental patient would prefer a white composite filling. However, in those cases where the cosmetic appearance of dental composite is placed ahead of a consideration of its (possibly less than optimal) physical properties, dental composite can be a poor choice.
B) Bonded fillings can often be smaller than amalgam ones.
When placing a dental filling a dentist will first use their drill and shape the tooth. Some aspects of this shaping are dictated by requirements associated with the type of dental filling material being used. Comparatively speaking, the required shape for a dental composite filling can typically be smaller than that shape required for a dental amalgam filling.
The flip side to this argument however could be as follows. Most dentists would probably feel that one of their primary treatment goals is to conserve as much natural tooth structure as is possible. In light of this statement you might anticipate that in most cases a dentist would likely recommend the placement of a composite filling rather than a dental amalgam restoration since the size of the cavity preparation can be minimized when dental composite is placed.
A point to the contrary could be made however. Since a composite filling quite possibly won't last as long as a dental amalgam filling and because each time a dental filling is replaced the overall size of the filling typically increases, placing dental composite may not be as conservative a treatment as one might have initially anticipated. Clearly it would take your dentist's evaluation and judgement to make a determination regarding this argument.
C) Composite fillings may help to strengthen the tooth.
Some dentists feel that teeth restored with dental amalgam fillings are more likely to experience cusp fracture than those teeth restored with tooth bonding (a composite filling). The thought is that the adhesive nature of the bond between the dental composite and the tooth serves to strengthen the tooth being repaired, as opposed to the typical dental amalgam filling where a bond with the surrounding tooth structure does not exist.
This conventional wisdom is not necessarily confirmed by dental research. One study (Wahl, 2004) evaluated the rate of tooth cusp fracture in more than 10,000 teeth that had either a dental amalgam or dental composite filling. The study's findings were that overall there was no significant difference in the rate of tooth cusp fracture in regards to either type of filling. As a conclusion, this study stated that when choosing between a dental amalgam filling and a dental composite filling (in regards to the likelihood of a future cusp fracture) that either type of filling should be considered acceptable.
To continue this discussion further, we would like to bring to your attention that even though conventional dental amalgam fillings do not create a bond with tooth structure there is a technique of using a bonding protocol with dental amalgam where such a bond is created. Two of our references (Rasheed, 2005 and Zidan, 2003) evaluated the use of bonded dental amalgam fillings as a means to reinforce weakened teeth and both studies found that this bonding technique did provide a benefit. More specifically, the Zidan study evaluated the effect of bonding technique on the stiffness of teeth. The study found that a dental amalgam filling alone did not provide a stiffening effect whereas bonded dental amalgam fillings and dental composite fillings both did. Bonded dental amalgam fillings on average restored teeth to 62% of their original stiffness whereas tooth bonding (composite fillings) on average restored teeth to 77% of their original stiffness.
A review of just these three studies is hardly conclusive (and we admit that comparisons of their individual findings are even somewhat contradictory) but these studies would lead us to believe that the tooth strengthening argument attributed to the use of dental composite is not as strong as some would claim. It seems just as valid to suggest that a bonded amalgam filling might provide the best choice in regards to tooth strengthening, since this technique can offer the more durable type of filling material and also the benefits of bonding technique. Clearly your dentist's evaluation of your specific situation should weigh heavily when making a decision regarding what type of filling is best for your tooth.
D) Teeth with bonded filling are usually less sensitive to hot and cold.
Dental amalgam is a metal and therefore is an efficient thermal conductor. This means that after amalgam fillings are placed (especially relatively large ones) it is common that people will experience a sensation in their tooth when they consume hot or cold foods and beverages. In most cases this thermal sensitivity will subside as days and weeks pass but for some people it most certainly can be a nuisance.
Since dental composite is a plastic it is a comparatively poor thermal conductor. This means that a strong sensitivity to hot and cold stimuli is usually not a problem with composite fillings. This is not to say that post treatment sensitivity is never occurs with composite fillings. In fact, especially during that era when creating an effective bond with tooth dentin was less well understood by dentists, sensitivity with dental bonding could at times be very problematic. Nowadays however, subsequent to the development of new dental bonding materials and protocols, the potential for post treatment sensitivity with dental bonding has become less of a concern.
E) Dental composite fillings are ready to be used immediately.
As a matter of convenience, a dental patient may be pleasantly surprised to find that the composite filling they have just had placed is fully cured (hardened) and ready for use. In comparison, dental amalgam fillings need several hours before they approach full strength.
2) Disadvantages of white fillings vs. dental amalgam.
A) Amalgam fillings are usually less expensive.
As a basis of comparison, the cost of a dental amalgam filling will usually be on the order of about 25% to 30% less than the cost of a comparable dental composite filling. This price difference reflects the relative cost of the materials involved and the relatively greater amount of time it takes the dentist to place a white filling as compared to a dental amalgam filling.
If cost is much of a concern, and you have dental insurance, you should be sure to ask your dentist's office staff about the specific details of your coverage. In some cases dental insurance plans do cover the cost of white fillings (composite fillings) but only up to that amount an equivalent dental amalgam filling would cost. This means that you, the dental patient, would pay the difference.
B) Amalgam fillings typically last longer.
The combined strength and wear characteristics of dental amalgam are typically considered to be superior to those of dental composite. This in turn implies that one would expect that an amalgam filling will last longer than a comparable composite filling. Of course there are a number of variables that become involved with any particular filling's longevity. In some applications (such as very small filling placed on a tooth surface not subject to direct chewing forces) for all practical purposes the anticipated life expectancy of both types of fillings might be very similar.
There have been a number of studies that have tried to evaluate the relative longevity of different types of dental fillings placed in back teeth. One study (Van Nieuwenhuysen, 2003) evaluated more than 100 dental composite fillings and 700 dental amalgam fillings. They found an average life span of 12.8 years for amalgam fillings and 7.8 years for composite fillings. Another study (Forss, 2001) calculated an average life span of 12 years for amalgam fillings and about 5 years for composite fillings. An evaluation of a dental insurance claims database (Bogacki, 2002) concluded that composite fillings in back teeth do not last as long as dental amalgam fillings.
To the defense of dental composite, not all studies have come to these same conclusions. Some studies have felt that they found little difference in the life span of dental amalgam and dental composite fillings. Certainly one might anticipate that as research and development continues to further improve the physical properties of dental composites that the discrepancy that exists between the longevity of dental amalgam and dental composite fillings will diminish. And probably most important, since there is a myriad of factors that come into play regarding the life span of a dental filling, it's probably best to rely on your dentist's judgement and experience when making a decision between the two.
C) Bonded restorations take longer to place.
Placing composite fillings is much more technique intense than placing dental amalgam fillings. This means it will take comparatively longer for your dentist to place a composite filling. The specific time difference will depend upon many factors such as the size and location of the filling but as a ballpark estimate it might take your dentist only about two thirds to half as long to place a dental amalgam restoration as opposed to a white composite filling.
D) Bonding is somewhat more difficult to place.
The process of placing composite fillings is fairly technique sensitive and certain steps of this technique do require that the tooth is isolated in a manner where it can be kept free of contamination by oral fluids. There can be instances where the location of a filling is such that it is essentially impossible for the dentist to adequately isolate the tooth. In these cases dental amalgam can often be placed and create a serviceable filling whereas dental bonding cannot.
E) White fillings will tend to discolor over time.
Dental composite fillings will characteristically pick up staining over time. However, when compared with the silver appearance of dental amalgam, it seems unlikely that the potential staining of a composite filling in a back tooth would be a reason not to place one.