Penetration of etching agents and its influence on sealer penetration into fissures in vitro

This study was designed to assess: 1) the ability of several commercially available and laboratory-made acid etchants to penetrate occlusal fissures when used for pit and fissure sealing, and 2) the influence of adding a surfactant to the etchant on penetration of the sealer. Viscosity, surface tension and contact angle to enamel of the etchants were determined for each treatment, and these properties were related to the etchant's ability to penetrate fissures.

Penetration was assessed in an acrylic fissure model having a deep-narrow fissure using a microscope and a chronometer. Penetration depth was expressed as percentage of total fissure depth and was measured in intervals up to 90 s. Commercially available etching agents with different viscosities and two solutions of phosphoric acid (37%), one with and one without a surfactant, were tested. The etch pattern obtained on the fissure wall enamel of extracted teeth with some of these products was evaluated using scanning electron microscopy. Eventually, the penetration depths of a composite sealer in fissures treated with a conventional etchant were compared to those after application of a surfactant-containing etchant on sections of extracted teeth.

None of the commercially available etchants studied were able to penetrate farther than 17% of the total fissure depth in the fissure model. The surfactant-containing etchant showed complete penetration within about 1 min and had a significantly lower surface tension and contact angle than the other products tested. Only the surfactant-containing etchant could produce a retentive pattern on the entire wall enamel of the fissure with the exception of locations blocked by debris and plaque. Fissures treated with this product prior to sealing showed a significantly deeper penetration of the sealer in deep-marrow fissures.

Surfactant-containing etchants with a low viscosity can penetrate completely into fissures and can produce an increased retentive and wettable surface which significantly increased sealant penetration into deep fissures.