title: Sequence of stannous and sodium fluoride solutions to prevent enamel erosion.
abstract: OBJECTIVE
  Investigate the timing of stannous (SnF2) and sodium fluoride (NaF) application with and without salivary pellicle to prevent enamel erosion.
  
  
  METHODS
  Human buccal molar enamel samples (n=120, REC ref 12/LO/1836) were randomly assigned to three groups testing SnF2 and NaF basic fluoride formulation and commercial mouthrinses with and without the presence of human saliva. Samples were randomly allocated to 2 subgroups: immersion in either fluoride for 1 min either before or after citric acid immersion (0.3%, pH 3.2, 10 min), and the cycle repeated 5 times. For human saliva group, samples were immersed in 80 ml of natural saliva for 24 h prior to the experiment. Analysis was done using non-contacting profilometry and microhardness change. Data were not normal and were log transformed. A linear model tested statistical differences between the groups.
  
  
  RESULTS
  SnF2 application before erosion statistically reduced step height compared to application after erosion for all groups (solutions: 6.5 μm (±1.2), 7.5 μm (±0.8); p=0.01, mouthrinses: 3.2 μm (±0.6), 4.2 μm (±0.7); p<0.0001, mouthrinses with saliva: 2.5 μm (±0.4), 3.1 μm (±0.6); p=0.002, before and after respectively). In contrast, application of NaF before erosion increased step height compared to application after, but this was only statistically significant for the saliva group (before: 5.6 μm (±0.3) and after: 4.9 μm (±0.3); p=0.023). Presence of saliva increased microhardness change (p<0.0001). Within this group, greatest microhardness change was observed when SnF2 was applied before erosion and when NaF was applied after erosion (SnF2: 156.6KHN (±32.8), 123KHN (±20.1); p=0.02. NaF: 119.5KHN (±33.5), 218KHN (±24.9), before, and after respectively).
  
  
  CONCLUSIONS
  SnF2 reduced step height formation overall when compared to NaF, but particularly when applied before citric acid immersion. In contrast, NaF reduced step height when applied after citric acid immersion, but only in the presence of saliva.
  
  
  CONCLUSIONS
  Stannous fluoride can be recommended over sodium fluoride to patients at risk of dental erosion and is optimally applied before erosion occurs. If sodium fluoride is to be used in the presence of saliva it is optimally applied after erosion has occurred.
authors.affiliation: King's College London Dental Institute, London, England, United Kingdom. Electronic address: saoirse.otoole@kcl.ac.uk.
authors.forename: Saoirse
authors.initials: S
authors.lastname: O'Toole
authors.affiliation: King's College London Dental Institute, London, England, United Kingdom.
authors.forename: Miten
authors.initials: M
authors.lastname: Mistry
authors.affiliation: King's College London Dental Institute, London, England, United Kingdom.
authors.forename: Mahdi
authors.initials: M
authors.lastname: Mutahar
authors.affiliation: Dental Institute Oral Clinical Research Unit, King's College London Dental Institute, London, England, United Kingdom.
authors.forename: Rebecca
authors.initials: R
authors.lastname: Moazzez
authors.affiliation: Prosthodontics, King's College London Dental Institute, London, England, United Kingdom.
authors.forename: David
authors.initials: D
authors.lastname: Bartlett
mesh_terms: D019343:Citric Acid / Q000737:chemistry; D003743:Dental Enamel / Q000187:drug effects* / Q000473:pathology*; D044622:Dental Pellicle / Q000737:chemistry / Q000187:drug effects / Q000502:physiology; D006801:Humans; D006863:Hydrogen-Ion Concentration; D020011:Protective Agents / Q000494:pharmacology; D011897:Random Allocation; D012463:Saliva / Q000502:physiology; D012969:Sodium Fluoride / Q000737:chemistry / Q000494:pharmacology*; D014002:Tin Fluorides / Q000737:chemistry / Q000494:pharmacology*; D014077:Tooth Erosion / Q000473:pathology / Q000517:prevention & control*; D057085:Tooth Wear / Q000473:pathology / Q000517:prevention & control
chemical_list: D020011:Protective Agents; D014002:Tin Fluorides; D019343:Citric Acid; D012969:Sodium Fluoride
keywords: Enamel; Erosion; Fluoride; Prevention; Saliva; Tooth wear