these products aim to remove surface extrinsic stains to

1
914 The effect of silica abrasivity and sodium
tripolyphosphate on tooth stain removal in
vivo Creeth J E1, Bosma ML1, Littlejohn S1,
Butler A1, Smith SR1, Chaves E2, Gallagher A2,
Sharma N3, Kleber K4, Milleman J4,
Davidson-Milleman K4 (1) GlaxoSmithKline,
Weybridge, UK (2) Hill Top Research, Cincinnati,
US (3) Biosci Research, Toronto, Canada (4)
University Park Research Center, Indiana, US.
RDA measurements were performed according to the
Hefferren method12, at the Oral Health Research
Institute, Indiana, USA. All products were
silica-based sodium fluoride dentifrices.
Changes in abrasivity were attained by changing
the grade of abrasive silica used. Content of
abrasive varied between 14 and 18 w/w. All but
the Control toothpastes contained sodium
tripolyphosphate (STP) at 10 w/w.

• Consumer interest remains strong in mass-market
  whitening toothpastes that claim to remove
  extrinsic tooth stain effectively during
  brushing. These products aim to remove surface
  (extrinsic) stains to reveal the natural, whiter
  appearance of the underlying enamel. Extrinsic
  tooth stain consists largely of dietary
  chromogenic molecules and metal ions, bound
  within the enamel pellicle layer1,2. Toothpastes
  remove this layer by two principle methods
• by incorporating insoluble abrasive particles
  that abrade away stained pellicle on the surface
  of the tooth3,4
• by incorporating polyphosphates, as mild calcium
  chelators with affinity for dental surfaces.
  These interfere with stained pellicle integrity,
  making it easier to remove by brushing5-8
• However, toothpastes should not be too abrasive,
  to avoid risk of toothwear due to brushing9,10.
  Although sound enamel appears essentially
  resistant to wear by conventional toothpastes
  over a lifetimes brushing11, dentine is softer
  and can be worn by poor brushing or highly
  abrasive toothpastes over a period of decades10.
• This poster describes a clinical study to
  investigate whether incorporating sodium
  tripolyphosphate (STP) and modest increases in
  the abrasive component of a toothpaste improve
  the stain removal performance of a toothpaste
  without an excessive increase in dentine
  abrasivity.

The data in Figure 1 show that both STP and the
abrasivity of the silica system increase stain
removal in vivo. The stain removal performance
of the toothpaste increased with the abrasivity
of the silica system used. The low-vs-medium
abrasive comparison was significant (plt0.05),
however the medium-vs-high abrasive comparison
was only of borderline significance. The
comparison of low-abrasive STP and Control
products, which contained the same abrasive
system, was of borderline significance (p0.06)
in this study.
The data also suggest that the stain removal
effects of increasing the abrasivity and
incorporating STP are additive.

• Both STP and increased silica system abrasivity
  improved stain removal performance in this study
• In particular, the medium-abrasiveSTP
  formulation outperformed the low-abrasiveSTP
  formulation, showing the benefit of a modest
  increase in silica system abrasivity using
  carefully chosen silica grades
• The abrasivity data indicate that, as stain
  removal performance improves, it becomes
  progressively more difficult to increase
  performance further
• A clear understanding of the contribution of
  different elements of a toothpaste formulation to
  stain removal and abrasivity can enable
  development of high-performance whitening
  toothpastes

This was a multi-centre, randomized,
evaluator-blind, four-group parallel study,
completed by 578 subjects. Assessment of natural
tooth stain was performed at baseline and week
12. Stain was assessed using the Lobene stain
index (LSI) ref Lobene 68. Briefly, the
intensity and area of stain on the gingival
crescent and the body of the buccal surfaces of
each assessable incisor and premolar were scored
visually using 4-point scales. Intensity 0no
stain 1light stain 2moderate stain 3heavy
stain. Area 0no stain detected, only tooth
colour 1stain covering up to one third of the
tooth surface 2stain covering between one third
and two thirds of the tooth surface 3stain
covering more than two thirds of the tooth.

• Addy M, Moran J. Mechanisms of stain formation
  on teeth, in particular associated with metal
  ions and antiseptics. Adv. Dent. Res. 9 450-456
  (1995).
• Nathoo SA. The chemistry and mechanisms of
  extrinsic stain formation. JADA 1286S-10S
  (1997)
• Barbakow F, Lutz F, Imfeld T. Abrasives in
  dentifrices and prophylaxis pastes. Quintessence
  Int. 18 17-22 (1987).
• White DJ. Development of an improved whitening
  dentifrice based on stain specific soft-silica
  technology. J. Clin. Dent. 1225-29 (2001).
• Yankell SL, Emling RC, Prencipe M, Rustogi K,
  Volpe AR. Laboratory and clinical evaluation of
  two tartar-control dentifrices (1995).
• Tantbirojn D, Ko C-C, Douglas WH. Stain removal
  efficacy An in vitro evaluation using
  quantitative image analysis. Quintessence Int.
  2928-37 (1998).
• Grossman E, Sturzenburger OP Bollmer BW Moore DJ,
  Manhard MD, Huetter TD. Reduction of calculus
  and Peridex-induced stain with Tartar Control
  Crest. J. Dent. Res. 66 279 (1987).elements of
  a toothpaste formulation can enable development
  of high performance whitening toothpastes
• Yankell SL, Emling RC, Petrone ME, Rustogi K,
  Volpe AR, Proskin HM. A six-week clinical
  efficacy study of four commercially available
  dentifrices for the removal of extrinsic tooth
  stain. J. Clin. Dent. 10 115-118 (1999).
• Kitchin PC. How abrasive need a dentifrice be?
  J Dent Res 27 501-506 (1948)
• Davis WB. Cervical enamel a danger zone. J
  Oral Rehab 6 385-389 (1979)
• Hooper S, West NX, Pickles MJ, Joiner A, Newcombe
  RG, Addy M. Investigation of erosion and abrasion
  on enamel and dentine a model in situ using
  toothpastes of different abrasivity. J. Clin.
  Periodontol. 30 802-808 (2003)
• Hefferen, JJ. A laboratory method for measuring
  dentifrice abrasivity. J. Dent. Res. 55 563-573,
  1976.

During the study period, the medium-abrasiveSTP
formulation removed twice the stain that was
removed by the Control product. The stain
removal performance of the products is compared
with their abrasivity in Figure 2. The data
support the view that, as stain removal
performance increases, it becomes progressively
more difficult to increase it further.