Dentifrices with proven clinical desensitization efficacy include formulations which form smear layers to block patent tubuli. SnF2 provides a spectrum of useful clinical activities including control of dentinal hypersensitivity. The relative efficacy of SnF2 formulations for providing desensitization may vary in rate of onset and duration of desensitization provided by tubule obturation (Zsiska et al., J Dent Res 2011; 90 (Spec Iss A): AADR/IADR 2634 and 2635).
Objectives: This study examined dentinal tubule occlusion effects of commercial stannous fluoride dentifrices and their mechanical and chemical durability in vitro.
Methods: Etched coronal dentin specimens prepared from extracted human third molars were randomized for tubule diameter and density and allocated to three dentifrice treatment groups (N=6) including I: Crest® Pro-Health (SnF2) II: Sensodyne Repair & Protect (SnF2) III Colgate Cavity Protection (MFP, neg. ctrl). Specimens were brushed with dentifrice for 5 brushing-cycles comprised of 2 minute paste applications followed by 1 hour saliva immersion. Post-brushing (PB) samples were gently agitated 16-hours in saliva to test smear layer physical durability (MC). Then specimens were challenged with citric acid pH3.5 for 1 minute to examine chemical durability (AC). Surfaces were imaged by light microscopy after 60 sec (PB1/2), 1 brushing cycle (PB1), 5 brushing cycles (PB5), mechanical (MC) and acid challenge (AC). Specimens were graded blind to treatment on a 6-point scale from 0: open tubuli to 5: no open tubuli, intact smear layer.
Results: PB1/2: I=1.64a II=0.80b III=0.13c PB1: I=2.25a II=1.54b III=0.31c PB5: I=3.95a II=2.53b III=0.73c MC: I=3.75a II=2.39b III=0.72c AC: I=3.55a II=2.20b III=0.78c (a≠b≠c p < 0.05 Students t comparison).
Conclusions: Stannous fluoride containing dentifrices differed substantially in onset of tubule occlusion and resistance to physical and chemical effects. These results point to clear differences in formulation efficiency in tubule obturation in vitro.