Method: For CLSM methodology, 800μ dentin-disks were cut from human molars, sanded, polished and etched with 6% citric-acid. Baseline CLSM images were collected using Leica TCS-SP2-CLSM. The occlusal surface of disks was treated (1min) with all the dentifrices, rinsed and incubated in pH7 phosphate-buffered saline for 2h. The treatment-incubation cycle was repeated for a total of 14-treatments followed by cola-challenge (1min) to test the acid-resistance. CLSM images collected after 14-treatments and after cola-challenge were compared to baseline images.
For HC methodology, dentin segments were cut from extracted molars, mounted on acrylic blocks, etched and connected to a Flodec apparatus to measure fluid-flow. Segments were divided into three groups (n=6) and treated (1min) with CPHUS, CPHC and CPH7C. The blocks were rinsed, connected to HC apparatus, and fluid-flow was measured and compared to baseline.
Result: CLSM images of the disks treated with TPS revealed significant improvements in occlusion and acid-resistance efficacy after 14-treatments and cola-challenge, compared to CPHUS, CPHC and CPH7C. Results supported by recent clinical study confirming hypersensitivity benefit of TPS to CPHUS. Among the Crest products, dentifrice containing stannous-fluoride, CPHUS, revealed better occlusion efficacy compared to dentifrice containing stannous-chloride, CPHC and CPH7C.
Consistent with CLSM methodology, by using HC apparatus CPHUS revealed significantly higher % reduction in fluid-flow after one-minute treatment compared to CPHC and CPH7C (p<0.05).
Conclusion: The new dentifrice (TPS) provided better dentinal occlusion and acid resistance efficacy when compared with CPHUS, CPHC, and CPH7C.