Erosion of enamel by noncarbonated soft drinks, with and without toothbrushing abrasion

1
Erosion of enamel by non-carbonated soft drinks,
with and without toothbrushing abrasion Catherine
A. Hemingway1, David M. Parker2, Martin Addy1,
Michele E. Barbour1 1Department of Oral and
Dental Science, University of Bristol, UK
2GlaxoSmithKline, Nutritional Healthcare, RD,
Coleford, UK
Aim The purpose of this study was to investigate
enamel loss after exposure to a selection of
popular, non-carbonated soft drinks, and to
investigate the effect of alternating erosion and
abrasion on enamel loss. Dental Erosion Dental
erosion is defined as chemical dissolution of the
dental hard tissues by acids, without the
involvement of bacteria. The severity of erosion
is related to several factors, including the
chemical properties of the erosive products, and
the frequency and method of consumption. Dental
Abrasion Dental abrasion is characterised by the
wearing away of the dental hard tissues through
physical means other than teeth. Brushing the
teeth immediately after consuming acidic products
accelerates dental mineral loss, as acid-softened
enamel is more susceptible to abrasion.
Measurement of erosion Enamel loss due to
erosion and abrasion was measured using a using a
non-contact optical profilometer (Proscan,
Scantron, Taunton, UK).
Methods Six soft drinks were selected on the
basis of popularity in the consumer market (Fig
1). These were cranberry juice (Ocean Spray),
apple juice (Tesco pure apple), orange juice
(Tropicana), apple drink (Robinsons Fruit
Shoot), orange drink (Capri Sun) and a
blackcurrant ToothKind drink (GSK Ribena TK).
pH, titratable acidity, Ca and PO4 were
measured. Enamel samples were embedded in epoxy
resin, and finely polished. A baseline
measurement of each sample was taken. The enamel
was partly covered exposing a 2 mm window. Group
A erosion only 6 enamel samples were exposed to
500 mL fresh drink at 36C. The samples were
rotated at 110 rpm, corresponding to a linear
velocity of 0.5 m/s. After 10 min, the samples
were removed and rinsed with distilled water and
enamel loss was measured. Each sample was then
taped again in the same position. This was
repeated for a further 7 exposures for each of
the 6 drinks. Group B Erosion and
abrasion Erosion was performed as for Group A.
After each erosive challenge the samples were
then subjected to an abrasive challenge to
represent toothbrush abrasion. Samples were
brushed with 25 strokes of the toothbrush using 2
standard toothbrush heads (Oral-B, size 35,
regular) weighted with 200g and BSI toothpaste in
a 13 ratio with tap water. Samples were then
profiled and then subjected to a further 7
erosion profile abrasion profile cycles.

• Discussion
• Erosion was correlated with pH but not
  titratable acidity. This study employed a large
  solution volume, thorough agitation, and
  clinically relevant exposure times, producing a
  constant composition chemical environment, which
  reduces the importance of buffering in the drink.
  
• Erosion was correlated with calcium
  concentration but not with phosphate
  concentration.
• The amount of enamel removed by
  toothbrush/toothpaste was different for samples
  exposed to different drinks, implying that the
  thickness of the softened layer is dependent on
  the chemical composition of the drink.
• Drinks which caused the greatest erosion also
  caused the greatest subsurface softening.

• Conclusions
• Erosive enamel loss is exacerbated by subsequent
  abrasion
• The thickness of the softened layer is a
  function of the chemical composition of the
  erosive medium
• Softened layer thickness is correlated with
  erosive potential
• pH influences erosion more than titratable
  acidity under constant composition conditions
• This research was supported by GlaxoSmithKline
  Consumer Healthcare.