The protective nature of pellicle towards toothpaste abrasion on enamel and dentine.
OBJECTIVE
To determine the protective nature of pellicle towards toothpaste abrasion.


METHODS
The enamel region of human enamel-dentine blocks was indented with a Knoop diamond and the profile across the enamel-dentine junction was measured. Blocks were either exposed to deionised water or placed onto intra-oral appliances and worn in the mouth to produce in situ pellicles. This was followed by a 10-day period of tooth brushing experiments. Each day, specimens were brushed with a slurry of either Toothpaste A (RDA=90) or Toothpaste B (RDA=204) for 25 cycles (10s) on a brushing machine. This was repeated three times per day for a total of 750 brushing cycles. Between brushing cycles specimens were returned to water or in situ. The geometry of the Knoop indents and the enamel-dentine profile were re-measured and the enamel and dentine wear calculated. Specimens were also prepared for TEM analyses.


RESULTS
The mean enamel wear (microm) for Toothpastes A and B (water) was 0.23 and 0.06, and for Toothpastes A and B (in situ) was 0.03 and 0.08, respectively. The mean dentine wear (microm) for Toothpastes A and B (water) was 5.08 and 6.03, and for Toothpastes A and B (in situ) was 1.94 and 1.70, respectively. For Toothpaste A, the presence of in situ pellicle significantly (p<0.05) reduced enamel and dentine wear compared to water and for Toothpaste B, dentine wear was significantly reduced compared to water. After tooth brushing, residues of the in situ pellicle layer could be detected on enamel and dentine surfaces by TEM analysis.


CONCLUSIONS
The study has demonstrated for the first time that the presence of pellicle can significantly reduce toothpaste abrasion.
Joiner
Andrew
A
Unilever Oral Care, Quarry Road East, Bebington, Wirral CH63 3JW, United Kingdom. Andrew.Joiner@Unilever.com
Schwarz
Annika
A
Philpotts
Carole J
CJ
Cox
Trevor F
TF
Huber
Karin
K
Hannig
Matthias
M
D000328:Adult; D003743:Dental Enamel / Q000473:pathology*; D044622:Dental Pellicle / Q000502:physiology*; D003804:Dentin / Q000473:pathology*; D006244:Hardness; D006801:Humans; D046529:Microscopy, Electron, Transmission; D020011:Protective Agents / Q000494:pharmacology*; D014072:Tooth Abrasion / Q000473:pathology / Q000517:prevention & control*; D014099:Toothbrushing / Q000295:instrumentation; D014100:Toothpastes / Q000009:adverse effects*; D014867:Water / Q000737:chemistry
D020011:Protective Agents; D014100:Toothpastes; D014867:Water