Laird Harrison

June 26, 2012

June 26, 2012 — Stepwise excavation of deep carious lesions results in better outcomes than complete excavation, researchers reported at the International Association of Dental Research (IADR) 90th General Session and Exhibition, being held in Iguacu Falls, Brazil.

In the stepwise method, clinicians partially excavate the lesion, leaving some carious dentin over the pulp. They seal the cavity and then return later to complete the excavation and place a permanent restoration.

Overall, 30.1% of the restorations placed after stepwise excavation failed after 3 to 5 years compared with 38.9% of those placed after complete excavation.

The research adds to a growing body of evidence that lesions can be restored without removing all the carious material.

In fact, lead author Lars Bjørndal, DDS, PhD, from the University of Copenhagen in Denmark, was surprised that the partially excavated group did not show even greater success compared with the completely excavated group.

"I had expected a larger difference because previous older and less controlled studies have indicated a difference of around 50%," he told Medscape Medical News by email. "But as a trial design becomes more and more controlled — this is a pattern that is very often noted — the difference between interventions is not that large."

For the study, Dr. Bjørndal and colleagues treated 143 patients with the stepwise method. The patients had cavities that penetrated 75% of the dentin.

Clinicians removed carious tissue from the periphery of the cavity, but they left soft, wet, pale dentin centrally on the pulpal wall. They dressed the remaining carious dentin with calcium hydroxide and sealed the cavity temporarily with glass ionomer.

After 8 to 12 weeks, they reentered the cavity and removed any remaining soft dentin. The cavities were then restored with OptiBond Solo Plus (KerrHawe) and Herculite XRV (KerrHawe).

As a control, the researchers restored similar cavities in 149 teeth, using direct, complete excavation, in which they removed all soft dentin in the first procedure. They then placed base material and a temporary restoration in the same way as for the stepwise excavations, and then, 8 to 12 weeks later, removed the temporary restorations, but not the base material, and placed a permanent restoration.

During the next few years, the researchers measured the pulp vitality and radiolucency in the restored teeth, defining pulp vitality as a positive response to cold or electricity. They diagnosed radiolucency if the apical part of the periodontal ligament space was at least twice as wide as in other parts of the root and the lamina dura was absent. They defined success as unexposed pulp with sustained pulp vitality without apical radiolucency.

After 3 to 5 years, 51 (35.7%) of the restorations done after stepwise excavations were successful compared with 36 (24.2%) of the restorations done after direct complete excavation. About half the teeth remain to be evaluated, Dr. Bjørndal noted.

The difference of 11.5% fell within the 95% confidence interval (0.5% - 22.2%), he added.

Dr. Bjørndal theorizes that the stepwise approach might be more successful because the temporary restoration arrests the progress of the caries without injuring the pulp.

In fact, the final excavation might not be necessary at all, he said, though he believes more research is needed.

That thought is shared by Van Thompson, DDS, PhD, chair of biomaterials and biomemetics at New York University College of Dentistry in New York City.

"There is no sense going in a second time," he told Medscape Medical News. "It's well established that if you can cut off the nutrient supply from outside, you stop the progression of the lesion."

The only reason for removing carious material at all is to give the restoration a strong enough foundation that it will stay on the tooth, said Dr. Thompson, who was not involved in Dr. Bjørndal's study.

Still, a lot remains to be understood, he cautioned. For example, how tightly must the restoration seal the lesion?

All restorations leak to some extent, but even amalgam restorations, which leak more than composite resin, can stop the progression of a lesion.

"You need a certain amount of fluid getting in to have the progression of caries, but we don't know how much," he said.

So why have dentists been trained to remove all the carious material from a cavity?

Peer pressure, he said. Dentists fear that any other dentists their patients visit might be critical of this approach.

Dr. Thompson and Dr. Bjørndal have disclosed no relevant financial relationships.

International Association of Dental Research (IADR) 90th General Session and Exhibition: Abstract 3032. Presented June 23, 2012.

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