Wear and morphology of infiltrated white spot lesions

To evaluate the toothbrush wear resistance of infiltrated artificial white spot lesions following two infiltration strategies, and to assess their ultramorphology.

Flat enamel surfaces from freshly extracted bovine teeth were polished and immersed in a Buskes demineralising solution for 30 days to create incipient caries-like lesions (white spots). Two experimental regions on the surface of each tooth were infiltrated with an infiltrant and a commercial etch-and-rinse adhesive. Toothbrush abrasion was applied for 20,000 cycles. Vertical wear loss of the infiltrated areas was measured after 10,000 and 20,000 cycles against unabraded and abraded enamel using confocal laser scanning microscopy (CLSM; multiple t-tests, α=0.05). Each lesion's surface and cross-section were evaluated under CLSM and scanning electron microscopy after etching and infiltration to assess ultramorphology.

After 20,000 abrasion cycles, a statistically non-significant difference in vertical wear loss was measured for the infiltrant versus the adhesive compared with the original enamel (42.6±20.7 μm vs. 40.4±18.5 μm, p>0.05). Irregular surface profiles were common for the adhesive-infiltrated group as a result of peeling and blistering of the resin-covering layer. Ultramorphology of the infiltrated lesions revealed different patterns of penetration regarding density and depth.

Although both infiltration strategies had equivalent wear resistance to toothbrush abrasion, surface and morphological aspects pointed to improved surface stability and infiltration quality for the infiltrant material.