Why do dental restorations fail

All rights reserved. Article Tools Print this article. Indexing metadata. How to cite item. Finding References. Email this article Login required. Email the author Login required. Home Vol 3, No 2 Mahajan. Alcohol was another factor, increasing the failure rate within two years. Perhaps most interesting is the role genetics play in failure rates. The researchers looked at 92 patients with a failed composite resin in either the anterior or posterior teeth.

They compared those patients with 92 other unrelated patients, who matched with the other group by type of restoration and other factors such as age, sex, ethnicity, and tobacco and alcohol use.

The authors could then examine the role matrix metalloproteinases MMPs play in failure rates. Related article: 5 ways your composite choice may be costing you money — and making your patients unhappy. MMPs are exposed and activated by acidic agents during the adhesive bonding process. The authors hypothesized that certain MMP alleles could increase the degradation of collagen fibrils at the resin—dentin-bonded interfaces, which could in turn lead to restoration failures.

Other research has shown that that specific genotype is found in 23 percent of Whites, 14 percent of Chinese and Japanese, and 1. In some instances, the manufacturer is the one to blame, as materials are often sent to the market based on laboratory testing without the proper clinical testing.

Generally, this is not the case, however. The principal reasons for failure are secondary caries, fracture, marginal deficiencies, wear, and postoperative sensitivity. In a recent prospective cohort study, 2 it was found that patient age, patient ethnicity, number of surfaces restored, dentist sex, and dentist practice workload were significant predictors of early restoration failure, whereas the restorative material used was not significant. Therefore, before assuming that failure stems from a problem with a material, it is important to consider other relevant factors that may contribute to the failure of a restoration.

Do you etch with phosphoric acid prior to use, and if so, for how long? Some composites require more curing time or smaller layers, whereas others need less light and can be bulk filled. Unless the instructions are read before use, the incorrect technique may lead to an inferior restoration, which leads to both an unhappy patient and dentist. Excellent moisture control of the operating field is extremely important for a successful restoration. The use of a properly placed rubber dam during placement of the composite material is ideal.

Restorations that were placed with a rubber dam have showed significantly fewer material fractures that needed replacement; this also had a significant effect on overall longevity. No system includes blood or saliva as part of the bonding technique. These systems can be a valuable addition when placing technique-sensitive materials and should be considered when help is needed placing hydrophobic resin materials and use of the rubber dam is not possible. These seem to be very interesting for future consideration.

Each composite requires a certain amount of energy joules for complete curing. This may vary by the manufacturer, by the type of composite material, and the shade of the composite. Unfortunately, the amount of delivered energy can vary due to the improper placement of the light tip, movement of the light tip during curing, distance of the light tip from the resin, shade and type of the resin material, condition of the light curing unit, or thickness of the resin.

Even the most powerful curing light will not cure a composite if it is not properly placed. Just because the top layer of the composite is hard, that does not mean that the composite is cured at the bottom.

In general, not enough attention is given to proper placement of the curing light or the condition of the light. The proper amount of irradiance is determined by the manufacturer and the shade of the composite.

Several surveys have shown that many QTH quartz-tungsten-halogen curing lights in dental offices do not deliver enough light energy to completely cure composites. The position of the tooth in the arch and the size of the cavity have been shown to be a factor in the success of a restoration.

One study found the risk of failure in the molar area to be twice as high as for premolars, 10 while another study placed the failure rate in lower molars as three times that of the upper premolars. Because of their low stress and good depth of cure, these composites may be the future. No matter which technique that is used, proper matrix placement is extremely important for the restoration success. A restoration that has an open contact or a gingival overhang is not an acceptable restoration.

Food impaction from an open contact does not lead to good gingival health and an open or rough margin may lead to bacterial growth and eventual recurrent decay. Sectional matrix systems and separating rings may lead better contours, contacts, and marginal seal.