How long does bonding last? / Comparisons to crowns, amalgam fillings, porcelain veneers.
This page covers issues related to the topic of how long tooth bonding can last - What research suggests. / Repairing bonding.
It also discusses those factors that can make bonding a good (or poor) choice when compared to other types of dental restorations (crowns, amalgam fillings, porcelain veneers).
How long will tooth bonding last?
While it is considered to be a "permanent" type of dental restoration, a patient probably won't get the same lasting service from tooth bonding as they would from amalgam dental fillings, porcelain veneers, or dental crowns. (Keep in mind, however, in regards to all types of dental restorations, the word "permanent" isn't an equivalent term for the phrase "will last forever.")
What does dental research suggest?
We found two studies that evaluated the relative longevity of different types of dental fillings placed in back teeth. One of these studies (Van Nieuwenhuysen, 2003) evaluated more than 700 dental amalgam fillings and 100 dental composite fillings. They determined that the average life span of the typical dental amalgam filling was 12.8 years whereas the average composite filling lasted 7.8 years. Another study's findings (Forss, 2001) calculated an average life span of 12 years for amalgam fillings and about 5 years for composite fillings.
Repairing tooth bonding.
There is one characteristic of tooth bonding that is essentially unlike any other type of dental restoration. In some cases where a defect with tooth bonding has been identified, it may be possible that your dentist can patch, touch up, or otherwise repair the bonding's deficiency without having to replace the entire restoration.
Of course this won't be true in all cases, you will simply have to defer to your dentist's judgment. But the potential for this type of relatively simple remedy can help to make bonded dental restorations a cost-effective choice in some applications.
When is dental bonding the right choice?
A) Bonding vs. dental crowns.
In some instances, a dental composite restoration (tooth bonding) will be placed as an alternative to having a dental crown made. In these types of situations, the bonded restoration is usually opted for due to cost considerations. (Composite restorations are typically less expensive than crowns.)
If the strength characteristics that a dental crown can offer really are needed, then a decision to place bonding as an alternative is really less than ideal, possibly significantly so. However, and primarily in regards to front teeth, while a dental composite restoration can't be expected to provide the same service as a dental crown, if a crown is not a possibility a bonded filling may have to suffice.
B) Dental bonding vs. porcelain veneers.
Dental bonding is sometimes placed as an alternative to porcelain veneers. Making this choice can be a suitable one but there are a number of considerations have should be evaluated before the option for bonding is chosen.
C) Bonded vs. amalgam dental fillings.
When creating restorations for back teeth, a dentist typically has three alternatives available: a composite filling (dental bonding), a dental amalgam filling (or even a bonded amalgam filling), or dental crown (or some other indirect, typically dental laboratory created, restoration).
Similar to our statement above, if the strength of a dental crown is needed then a dental amalgam or dental composite filling makes a less than ideal alternative. Neither can be expected to last as long. And placing either one instead of a crown can put the tooth at risk for fracture.
If, however, for financial reasons the cost of the dental crown is not a possibility then one of the alternatives needs to be chosen and in most cases it seems to us that the dental amalgam filling would be the better choice.
There is no question that the combined strength and wear characteristics of an amalgam filling would be superior to a composite one. And most likely the amalgam filling would cost less. To us, it seems the only reason to consider the composite filling would be related to its more appealing cosmetic appearance. However, in the vast majority of cases, opting for an inferior dental restoration solely because it has a more pleasing cosmetic appearance would seem to be a poor choice.
What can cause a bonded restoration to fail and need to be replaced?
A) Over time dental bonding can stain and discolor.
One of the disadvantages of using dental bonding to create dental restorations is that it will usually pick up stain over time. And since the cosmetic appearance of the bonding can be one of its most important attributes, staining may be one of the main reasons why a dental patient and their dentist might determine that the bonding has served its useful life span and should be replaced. The potential for staining to occur will be greater for those people whose consumption habits include the use of coffee, tea, dark cola, red wine, or tobacco products.
That staining that does occur can take a couple of different forms. In some instances the tooth bonding as a whole will become discolored. In these cases it may be that the entire restoration needs to be replaced or it could be that just that portion of the restoration that shows when the person smiles needs to be resurfaced. In other cases the staining that forms might lie at the edges of the dental bonding. Sometimes this type of staining can be buffed off just by polishing the dental bonding.
B) The bonding has worn out.
Tooth bonding does not have the same combined wear and strength characteristics that dental amalgam and other types of dental materials do. And for this reason, restorations made out of dental composite can't be expected to last as long. Especially in the case (as described below) where relatively large bonded restorations have been placed, the trend will be one where they can be expected to deteriorate and fail (wear down, wear out, break) with greater frequency than other types of dental restorations.
The useful life span of tooth bonding can, at least in part, be correlated to both the size of the filling and the type of forces it is subjected to. As a general rule you could anticipate that a smaller composite filling would fair better and give longer service than a relatively larger one. A composite filling placed on the side of a back tooth would be expected to have a longer life span than one found on its chewing surface. Composite fillings placed in the teeth of people who clench or grind their teeth would be expected to give less lengthy service that those composite fillings placed in the teeth of people who do not have these habits.
C) The tooth structure that holds the bonded restoration in place has become compromised.
Tooth fracture is one reason why tooth bonding may need to be replace. No filling material restores a tooth to its original strength and because of this at times some teeth (even one whose dental bonding is perfectly intact and serviceable) will chip or break off.
Another reason why tooth bonding may not "last" is because the formation of tooth decay. It is possible that the adhesion between the bonding and the tooth has deteriorated and as a result bacteria have seeped inside the tooth and formed a cavity. Equally likely, however, is that the new decay is simply the product of a person's ineffective home care (inadequate brushing and flossing) and the decay's location in proximity to a tooth's existing dental bonding is just coincidental.