A new electrical method for detecting marginal leakage of in vitro resin restorations

Ingress of bacteria at sites of marginal leakage has been suggested to cause pulpal inflammation. The purpose of this in vitro study was to evaluate the validity of a new electrical method to detect marginal leakage of restoratives by comparing the results obtained with those of a dye penetration test.

After cavities were prepared on the buccal coronal surfaces and root surfaces of 16 extracted non-carious human molar teeth, eight specimens were treated with a dentin bonding system (bonding group) and the other eight specimens were not treated (non-bonding group). Resin composites were filled in the cavities of all specimens, and physiological saline was applied to the margin of the restorative. Any excess saline was wiped off, leaving only the electrolyte, which had penetrated into the marginal gap. The change in conductance was measured continuously across the margin of each specimen during this process. The marginal leakage of specimens was confirmed using the dye penetration test, and the results were evaluated by the microleakage score.

In both coronal and root surface cavities, the changes in conductance in the non-bonding group after filling were significantly larger than those of the bonding group (p<0.05). The change in conductance of each specimen correlated with the microleakage score (p<0.05).

It was concluded that the relative electrical method could detect marginal leakage in both coronal and root surface cavities.