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The successful management of
dentin hypersensitivity is often very challenging for the dental professional
and the afflicted population. Many treatments have been proposed over the years
and one of these treatment options has been the use of stannous fluoride.
Dentifrice formulations using stannous fluoride have been shown not only to be
effective against caries, but also against dentin hypersensitivity.
A new stannous fluoride-based dentifrice has been introduced to treat
dentin hypersensitivity. The formulation approach adopted was the use of a
non-aqueous, i.e. water-free
formulation base stannous fluoride dentifrice. To optimize the cleaning
efficacy of the product, a high cleaning silica was utilized and combined with
a polyphosphate (sodium tripolyphosphate) to give a
formulation with a high pellicle cleaning ratio, but with only a moderate
relative dentin abrasion (RDA).
The new stannous fluoride-based dentifrice has been tested clinically and in the laboratory, and the results of these studies are presented in this Special Issue of the American Journal of Dentistry. In
summary, the first paper is a comprehensive review of stannous fluoride
dentifrices. The second paper demonstrates in vitro that this anhydrous
stannous fluoride-containing formulation occluded dentin and that this
occlusion was resistant to an acidic challenge. The third paper shows the
effect of Sensodyne Repair and Protect on the
resistance of an artificially established smear layer. The fourth paper, utilizing
a number of advanced analytical and visualization techniques to characterize
the physical and chemical nature, reveals that treatment with Sensodyne Repair and Protect resulted in an occlusive layer
on the surface of dentin which was up to 3 µm thick and extended down into the
dentin tubules. The fifth paper presents the results of a randomized,
examiner-blind 8-week clinical study confirming the effect this reparative
layer had on dentin hypersensitivity. The final paper shows that there were no significant differences in dental stain
build-up between the test formulation and the marketed negative control sodium monofluorophosphate dentifrice, in a randomized, examiner-blind study.
We hope you will find these
papers interesting and educational. The Journal thanks GlaxoSmithKline,
the manufacturer of Sensodyne Protect and Repair desensitizing
paste, for sponsoring this Special Issue.
Franklin García-Godoy,
Editor
Stephen
A. Makin, phd
Abstract: Purpose: Stannous fluoride has a
long history of use in the improvement of oral health, and was the fluoride
source first proven to provide anti-caries benefits when delivered from a dentrifrice formulation. This paper provides an account of
the early use of stannous fluoride, primarily for an anti-caries benefit, and
the subsequent attempts to formulate stannous fluoride into stable formulations
where additional benefits of the stannous cation can
be realized. (Am J Dent 2013;26:3A-9A).
Clinical significance: The improved
understanding of the mechanism of action of stannous, along with advances in
the understanding of stannous stability have enabled the formulation of a novel
anhydrous stannous-fluoride containing product, Sensodyne Repair and Protect. This formulation has been demonstrated to have
anti-dentin-hypersensitivity activity via an occlusive mode of action,
involving the deposition of a ‘reparative’ layer which gives rise to lasting
relief from the pain of sensitivity. This product has been optimized for its
ability to both remove existing extrinsic stain while preventing the build up of new stain via the incorporation of sodium tripolyphosphate.
Mail: Dr. Stephen A. Makin, GlaxoSmithKline Consumer
Healthcare, St Georges Avenue, Weybridge, KT13 0DE
United Kingdom. E-mail: stephen.a.makin@gsk.com
In vitro studies investigating the dentin
tubule-occlusion properties
of an experimental anhydrous stannous fluoride
dentifrice
Gary R. Burnett, msc, phd, Richard J. Willson, phd & Robert A. Lucas, phd
Abstract: Purpose: To evaluate in vitro the ability
for an experimental anhydrous 0.454% w/w stannous fluoride dentifrice to
occlude dentin tubules. Methods: Scanning electron microscopy (SEM) was used to assess tubule occlusion and the
resistance of the occlusion to dietary acid in a 4-day model, where bovine
dentin was treated with product twice daily with acid challenges administered
on Days 3 and 4. The reduction in hydraulic conductance of the dentin following
treatment was also measured. Results: The experimental stannous fluoride dentifrice was effective at reducing the
hydraulic conductance of dentin by occluding tubules. The occlusion was
resistant to challenge with grapefruit juice. (Am J Dent 2013;26:10A-14A).
Clinical significance: The experimental anhydrous
0.454% w/w stannous fluoride dentifrice forms an acid-resistant layer on dentin
that provides an occlusive barrier to tubular fluid flow.
Mail: Dr. Gary R. Burnett, GlaxoSmithKline
Consumer Healthcare, St Georges Avenue, Weybridge KT13
0DE, United Kingdom. E-mail: gary.r.burnett@gsk.com
The effect of an experimental anhydrous stannous
fluoride dentifrice
on the acid resistance of dentin smear layers
Gary R. Burnett, msc, phd
Abstract: Purpose: To compare the relative
performance, in an in vitro assay, of a standard dentifrice (Colgate Cavity
Protection) with an experimental anhydrous 0.454% w/w stannous fluoride
dentifrice at protecting the dentin smear layer against dietary acids. Methods: Artificial smear layers were
created on bovine dentin, contacted with slurries of the dentifrices, then
exposed to a dietary acid (Coca Cola) for periods up to 10 minutes. Both the
stability of the smear layer and tubule occlusion were assessed qualitatively
by scanning electron microscopy and confocal laser
scanning microscopy. Results: Smear
layers treated with the standard dentifrice were removed after 2 minutes of
exposure to cola with the smear plugs progressively eroded by longer acid
challenges, leaving patent tubules. Treatment with the experimental stannous
fluoride dentifrice provided extensive protection of the smear layer against
cola for up to 10 minutes, with very few tubules unoccluded.
(Am J Dent 2013:26:15A-18A).
Clinical significance: The experimental anhydrous
stannous fluoride dentifrice protected the smear layer against dissolution by
dietary acids, reducing the occurrence of patent tubules.
Mail: Dr. Gary R. Burnett, GlaxoSmithKline Consumer
Healthcare, St Georges Avenue, Weybridge, KT13 0DE United
Kingdom. E-mail: gary.r.burnett@gsk.com
Physical and chemical characterization of the surface
layers
Jonathan
S. Earl, phd & Richard M. Langford, phd
Abstract: Purpose: To characterize, in vitro, the mode of action of stannous fluoride
containing formulations in occluding dentin tubules, by means of high
resolution microscopy techniques. Methods: Focused ion beam scanning electron microscopy (FIB SEM) was used to
site-specifically prepare cross sections for SEM and TEM imaging and analysis
of dentin samples treated with either a stannous fluoride dispersion in
glycerol or an experimental stannous fluoride dentifrice. Results: An experimental stannous
fluoride dentifrice formed a protective layer over the dentin surface and
occluded dentin tubules. Additional supporting data derived from a stannous
fluoride dispersion in glycerol suggest that stannous fluoride is a key
component of this occluding system. Multiple SEM images obtained from
sequential FIB cross-sections were reconstructed into 3-dimensional tomograms
that showed a formed layer and tubule occlusion. Sections thinned by FIB
techniques were observed by transmission electron microscopy (TEM) and related
methods and showed that the coating, which was up to 3μm-thick, consisted
of a tin containing precipitate. Chemical analysis by energy dispersive x-ray
spectroscopy (EDS) mapping that used scanning TEM (STEM) methods showed interdiffusion of tin up to 200 nm into the dentin
structure. (Am J Dent 2013;26:19A-24A).
Clinical
significance:The data presented here are supportive of an
experimental anhydrous stannous fluoride dentifrice being suitable for
treatment of dentin hypersensitivity through an occlusive mode of action by
means of layer formation and direct dentin tubule occlusion.
Mail: Dr. Jonathan S. Earl, GlaxoSmithKline Consumer Healthcare, St
Georges Avenue, Weybridge, KT13 0DE United Kingdom.
E-mail: jonathan.s.earl@gsk.com
The efficacy of an experimental dentifrice
containing 0.454% w/w stannous
An 8-week clinical study.
Charles Parkinson, phd, Nathan
Hughes, msc, Peter
Jeffery, pgd, Ritika Jain, msc,
Liam Kennedy, msc, cstat, Jimmy Qaqish, bs, John T. Gallob, dmd & Stephen Mason, phd
Abstract: Purpose: To compare the efficacy of a
0.454% w/w stannous fluoride containing anhydrous dentifrice and a negative
control dentifrice containing 1,000 ppm fluoride (as
sodium monofluorophosphate) at reducing dentin
hypersensitivity over an 8-week period, following twice daily brushing. Methods: This was a randomized,
examiner blind, two-treatment arm, stratified (by maximum baseline Schiff
sensitivity score), parallel design, single-site study in 118 subjects, who had
at least two sensitive teeth, and met all the criteria at the screening and baseline
visit. The study was conducted in Las Vegas, NV, USA. Tactile threshold (Yeaple Probe) and evaporative (air-blast) sensitivity (with
Schiff sensitivity scale) were employed as clinical measures to compare the
efficacy of the test dentifrice containing 0.454% w/w stannous fluoride to the
negative control (Colgate Cavity Protection) at reducing sensitivity at Weeks 4
and 8. Results: 117 subjects
completed the clinical study. At the 4- and 8-week time points, between
treatment analyses demonstrated the test dentifrice to be significantly better
at relieving subjects’ sensitivity, for both validated clinical measures,
compared to the negative control (at 4 weeks Schiff P< 0.0001 tactile
threshold P< 0.0001; at 8 weeks Schiff P< 0.0001; tactile threshold P<
0.0001). (Am J Dent 2013;26:25A-31A).
Clinical significance: An experimental 0.454% w/w stannous
fluoride anhydrous dentifrice provided significant improvements in dentin
hypersensitivity, relative to a negative control dentifrice, after 4 and 8
weeks of twice daily brushing. The magnitude of the improvements may be
considered clinically relevant.
Mail: Dr. Charles Parkinson, GlaxoSmithKline
Consumer Healthcare, St Georges Avenue, Weybridge, KT13
0DE United Kingdom. E-mail: charles.x.parkinson@gsk.com
A randomized clinical study investigating the
staining profile
of an experimental stannous fluoride dentifrice
Marc Nehme, dds, msc, Stephen
Mason, phd, Nathan
Hughes, bsc, Darren Targett, msc,
Charles Parkinson, phd, Deci Tyson-Johnson, Liam
Kennedy, msc, cstat & Jeffery Milleman, dds, mpa
Abstract:
Purpose: The
primary objective of this study was to investigate the staining profile of an
experimental test dentifrice containing 0.454% w/w stannous fluoride compared
to that of a marketed control dentifrice containing 0.76% w/w sodium monofluorophosphate (Colgate Cavity Protection) following
regular and repeat use, with twice daily brushing over 8 weeks. As an
exploratory objective, the staining profile of the test dentifrice was compared
to that of a marketed comparator dentifrice containing 0.454% w/w stannous
fluoride (Crest Pro-Health – Clean Mint). Methods: This was a single-center, examiner-blind, randomized, three arm, parallel
group study, stratified by pre-baseline stain score [total Lobene Stain Index (LSI) (area × intensity) score < 31, ≥ 31] and smoking
status. Following initial screening, 137 healthy subjects, aged 18 years and
above, with 12 gradable anterior teeth returned for baseline assessments. At
the baseline visit, subjects received an oral soft tissue (OST) examination and
an assessment of extrinsic dental stain using the LSI on the facial and lingual
surfaces of the 12 anterior teeth, LSI area, LSI intensity and LSI area × intensity
(the LSI area × intensity score was
termed the pre-baseline LSI score). Subjects who met study requirements
received a dental prophylaxis of the anterior teeth to remove all visible stain
from their tooth surfaces such that an LSI (area × intensity) score of 0 was achieved. Randomized subjects brushed
with their assigned dentifrice at home twice daily for 1 timed minute and
returned after 4 and 8 weeks for an OST examination and dental stain assessment
of the anterior teeth using LSI. Results: There were no statistically significant differences in dental stain build-up
between the test dentifrice containing 0.454% w/w stannous fluoride and a
marketed control dentifrice (Colgate Cavity Protection), after 4 and 8 weeks of
twice daily brushing, in terms of LSI area × intensity, LSI area or LSI intensity scores. Exploratory analysis indicated
that the marketed stannous fluoride dentifrice (Crest Pro-Health) exhibited
more dental stain build-up at 4 and/or 8 weeks compared to the other two study
dentifrices. However, post-hoc analysis revealed an imbalance in LSI baseline
stain levels between the treatment groups, with higher stain levels in the
marketed comparator group, which made it difficult to draw robust conclusions
from the exploratory data. This imbalance was not considered to impact the
other study analyses. Study treatments were well tolerated. (Am J Dent 2013;26:32A-38A).
Clinical significance: In this clinical model, the
experimental test dentifrice containing 0.454% w/w stannous fluoride
demonstrated no statistical significant difference in stain build-up compared
to a marketed, standard fluoride dentifrice (Colgate Cavity Protection) as
control.
Mail: Dr. Marc Nehme,
GlaxoSmithKline Consumer Healthcare, St Georges Avenue, Weybridge,
KT13 0DE United Kingdom. E-mail: marc.m.nehme@gsk.com
