Dentinal tubule occlusion with lanthanum fluoride and powdered apatite glass ceramics in vitro.

To simulate hypersensitive dentin, the smear layer and dentinal plugs of bovine root dentin specimens were removed by immersion in 10% phosphoric acid, polishing with hydroxyapatite particles, and ultrasonic cleansing. The fluoride-tannic acid-lanthanum-apatite (FTLA) group was treated with acidulated phosphate fluoride (APF) containing tannic acid followed by rubbing with a paste of lanthanum chloride (LaCl3) and powdered apatite glass ceramics. The treated specimens were immersed in a remineralizing solution that mimics saliva for 6 weeks. The SEM observations revealed that the treated surfaces of the FTLA group were completely covered with fine spherical compounds and the dentinal tubules were occluded with plugs to a depth of about 3 microns. Fluoride and lanthanum were detected to a depth of over 20 microns by EPMA observation. After the remineralization, the surface of FTLA-treated specimen did not have any opened tubules and showed a remarkable increase in the number of fine spherical deposits in the dentinal tubules. These results suggest that the reaction products produced by sequential treatment with acidic fluoride and LaCl3 and powdered apatite glass ceramics are able to effectively occlude dentinal tubules.