What might cause dental bonding to fail? How long can a bonded restoration last?

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 physical properties of the dental composite have been exceeded.

Tooth bonding does not have the same combined wear and strength characteristics that dental amalgam fillings and other types of dental restorations do. So along these lines, one could expect that restorations made using dental composite will 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) Dental bonding can fail because of changes associated with the tooth structure that surrounds it.

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 need to be replaced is associated with 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.

A) About choosing tooth bonding for front teeth.

In some instances a dental composite restoration might be chosen as an alternative to a dental crown for a front tooth. If the strength of a crown really is needed then placing tooth bonding really is less than ideal. In a situation like this dental bonding is usually chosen because of cost factors, the bonding being the less expensive than a dental crown. And while the dental composite won't be expected to give the same service as the dental crown, if a crown is not a possibility there really is no other option other than tooth bonding.

Dental bonding is sometimes chosen as an alternative to porcelain veneers. This can be an appropriate choice. Factors associated with making this decision (especially cost, longevity, and type of expected cosmetic end result) are covered in detail elsewhere in this topic (use this link).

B) About choosing a bonded dental restoration for back teeth.

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). In the same vein as our example above, if the strength of a dental crown is needed then the dental amalgam or dental composite fillings are less than ideal alternatives.

If 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 the amalgam filling would be greater than the composite filling. Most likely the amalgam filling would cost less than a composite filling. In a situation like this, it seems the only reason to consider the composite filling would be related to its more appealing cosmetic appearance. Selecting an inferior dental material based solely on its cosmetic appearance would seem to be a poor choice.

[ This link can provide you with more information about choosing between composite fillings and dental amalgam fillings for back teeth. ]