Enamel Surface Properties After Conditioning With Hydrochloric Acid

Method: Of 12 extracted caries free human incisors the vestibular surface was covered with acid resistant varnish leaving 4 windows of 2x2mm size. The enamel surface was conditioned for 2, 2x2, 3x2 and 4x2 minutes with 15% hydrochloric acid. After each conditioning cycle the surface was washed for 30 seconds with H₂O. After dying the surface roughness and the enamel substance loss was determined using an optical profilometer. The quantitative roughness data were analyzed with the Wicoxon test for related variables. Morphological alterations of the surface were investigated using scanning electron microscopy (SEM).

Result: Substance loss of enamel increased with increasing conditioning t ime. The biggest enamel loss occurred after 2 minutes conditioning (median 34.02; 25% percentile 28.4; 75% percentile 41.08). Roughness increased significantly after 2 minutes conditioning. No further differences in roughness were found after repeated conditioning. SEM revealed inhomogeneous prism core demineralization which increased with repeated conditioning.

Conclusion: Enamel surface conditioning results in a destruction of the enamel surface which has to be taken into account before treatment of white spot lesions with resin infiltration.