Dentin sensitivity is one of the most
painful and least predictably treated
clinical conditions. It has been established
that dentin hypersensitivity affects 1 in 6 people.1
The clinical
challenge to treat hypersensitivity may be to occlude patent
tubules to reduce any stimulus-evoked
fluid flow and
The aim of this
study was to assess a new protective
root sealant for the treatment of cervical
sensitivity by the employment of sensitivity
scores, modified United States Public
Health Service (USPHS) criteria, microbiological
and novel three-dimensional
analyses.
Materials and Methods
Study
population
This 19-month study was carried out with
patients recruited from those attending
the Department of Adult Oral Health at St. Bartholomew's
and the Royal London School of Medicine
and Dentistry. Ethical approval was obtained
from the Local District Ethics Committee
(P/97/282) prior to the commencement of
the study. A total of 24 patients with
at least one cervical sensitive dentin
were selected and signed consent forms
were obtained. The mean ± standard error
(S.E.) age of the subjects at baseline
was 60.17 ± 2.48 years with a minimum
age of 24 and maximum of 76 years.
The protective
root sealant
This root sealant (Seal
& Protecta) contained a
mixture of dimethacrylate resins in acetone
as a solvent, with triclosan and fluoride.
Study
design
Baseline -
Patient
questionnaires, plaque samplings and standardized clinical assessments
using an air sensitivity score were carried
out. The air sensitivity scores were determined
using an application of air (25 PSI) from
a three in one syringe lasting 1-second
and directed perpendicular to the cervical
surface at a distance of 0.5 mm. The patients
were asked to rate the perception of sensitivity
experienced during this air stimulation
by providing a mark on a scale from 0
to 9. A score of 0 was defined as no pain,
1-4 as mild sensitivity and 5-9 as strong
sensitivity (which was reported spontaneously
by the patients during eating, drinking
and/or brushing their teeth).
The cervical
surfaces were then cleaned using a slow-speed
handpiece
with a rubber cup and prophylaxis
paste. An impression
using light-bodied addition-cured silicone
(Extrudeb) impression material was
then taken from the cervical
dentin surfaces as
described by Jovanovski et
al.4
The
root sealants were applied and agitated over the surface
of the cavity for 30 seconds and each
increment was cured with
the same light curing equipmenta
for
a period of 20 seconds according to the manufacturer's recommendations.
Five increments of
the root sealant were applied on each cervical surface. Each sealant
was then polished using a slow
speed handpiece with a rubber cup
and prophylaxis paste. Second
impressions were taken to
measure the thickness of the sealant
by the employment of 3-D digitization. Following
the application of root sealant, color, marginal adaptation,
anatomic form, surface roughness and
marginal discoloration were assessed
by modified USPHS criteria.5
All patients were given oral
hygiene instructions and dietary advice.
Clinical assessments regarding sensitivity scores and modified USPHS
criteria were carried out after 3, 6
and 19 months.
Three-dimensional data analyses
- Impressions
were taken from the sealants at baseline
and after 3, 6 and 19 months as described
by Jovanovski and Lynch.6
The volume and area of applied sealants were measured
using computer models of the replica
surfaces reconstructed from data acquired
by a Co-ordinate Measuring Machine (Merlin
Mk II 750c) fitted
with a laser probe (Renishaw OP2d). Three-dimensional coordinates
were acquired from the surface of each
replica with a spacing
of 100 µm in the x‑y plane to obtain a data set consisting
of approximately 10,000 data points
per.
Sequential
data sets from each subject at baseline,
3, 6 and 19 months were superposed
(brought into a common reference frame)
for the comparison
replica.4,6,7
Microbiological analyses - At baseline,
plaque samples were taken from the untreated
sensitive dentin surfaces using a sterile
dental excavator. After 3 and 19 months,
plaque samples were also taken from
the surface of each sealant. If the
sealants were lost, plaque samples were
carried out from sensitive cervical
surfaces of the teeth. Each sample was
then immediately placed in 1 ml of fastidious
anaerobe broth (FAB LABMe)
and forwarded to the microbiological
laboratory within 30 minutes for microbiological
investigation. The sample processing
methods described by Beighton et al8 were performed.
Statistical
analyses
Sensitivity scores - At baseline
and at time points of 3
Three-dimensional data analysis
- The wear of the sealant was summarized into a single numerical value by
measuring the volume loss over a square
region of standard size (µm2)
located around the mid-line (or alternatively,
around the area of maximum loss) at
the time points of 3, 6 and 19 months.
Since the region size was standard,
the mean depth of the wear over such
a region was proportional to the lost
volume. The means (± S.E.) of the sealant
thickness and wear on the sealant were
then recorded.
Microbiological analyses - Microbiological
counts from baseline and at time points
of
Results
Twenty-four subjects were enrolled into
the study. All subjects received the assigned
treatment at baseline. After 19 months,
20 subjects finished the study. There
were no observed adverse events. This
study assessed whether the root
sealant was capable of reducing sensitivity
and remaining on the cervical surface.
The numbers of representative caries associated
microorganisms in the overlying plaque
were also determined.
When the cervical surface was sealed, further wear on the cervical surface
was prevented. Sealing dentin tubules
with this root sealant reduced sensitivity.
This novel sealant was associated with
a reduction in the numbers of some representative
caries associated microorganisms in
the overlying plaque after 3 months.
Sensitivity scores - There was a
significant reduction for the sensitivity
scores (mean ± S.E.) 0.36 ± 0.12 at
3 months follow-up (P<
0.0001); 0.94 ± 0.40 after 6 months
and 2.08 ± 0.78 after 19 months (P< 0.001); compared with baseline 6.95 ± 0.27 (Fig. 1).
Figure 1. Sensitivity
scores at baseline and at time points
of 3, 6 and 19 months.
Modified USPHS criteria - All sealants
were clinically assessed for color match,
marginal discoloration, anatomic form,
marginal adaptation, surface roughness
and secondary caries after 3, 6 and
19 months. These results were as follows:
3-month follow-up - There were
6-month
follow-up - No discolorations, 9 anatomic form failures,
8 marginal
fractures, 4 sealants with surface roughness
and 4 lost sealants were recorded.
19-month follow-up - No discolorations, 12 anatomic form failures, 12
marginal fractures, 8 sealants with
surface roughness and 5 lost sealants
were observed.
Three-dimensional data analyses
- The mean
(µm)
(± SE) sealant thickness was 169.2 ± 3.5 at baseline (Fig. 2). Mean
(µm) (± SE) wear on the root sealant
was 78.8 ± 5.1 at the 3 month follow-up, 95.4 ± 7.1 after
6
months and 136.5 ± 8.9 at the
19 month follow-up (Fig. 3). After 19 months,
the mean wear was less than the mean
sealant thickness.
Fig. 2. Color-coded
subtraction image of ‘before sealant
application’ and ‘after sealant application’
surfaces.
Fig. 3.
Sealant wear at 3, 6 and 19 months - Subtraction maps.
Microbiological analyses - The effects
of the sealant on the representative
caries associated microorganisms were
evaluated before application of sealant
and at time points of 3 and 19 months
as shown in Table 1.
Discussion
In this study,
sensitivity scores were dramatically
reduced after 3 months compared to baseline
and were still significantly less than
the baseline scores after 6 and 19 months.
These significant differences were likely
to have been related to the sealing
of this protective material on the patent
dentin tubules. The resistance to wear
during 19 months was less than anticipated.
It can be speculated that this may have
been related to the hydrophilic resin
and additional added constituents in
the sealant. Sensitivity scores slightly
increased after 19 months when compared
to those at the 3 and 6 month recalls.
However, this increase in sensitivity
scores in the test teeth (n = 5) was
entirely associated with lost sealants
as measured clinically on the same teeth.
It should be noted that patients with
intact sealants on the cervical surfaces
presented no sign of sensitivity during
the study.
It was surprising that the reduction of some of the
micro-organisms persisted for 3 months.
This may be associated with several
factors including smoothness of the
resin surface, release of cytotoxic
constituents from the sealant, the different
contact angle and/or surface energy
of the sealant compared to the previous
tooth surface. Siegrist et al.,9 showed a similar
effect on the reduction of plaque deposition
on different dental materials. These
authors showed that smooth surfaces
such as gold harbored sparse deposits,
while the rougher materials (e.g.,
amalgam) were covered by more plaque.
Sealing of the rough exposed dentin
surfaces with this smooth sealant may
have also been associated with less
plaque accumulation. In addition, the
operative procedure itself might have
had some impact on these results.
It is widely
known that S.
mutans is the predominant micro-organism
in the initiation of root caries. Beighton
et al.,8 found that root caries which
were situated within 1 mm of the gingival
margin had an increased frequency of
isolation of mutans streptococci, lactobacilli,
and yeasts. In this study, the numbers
of isolated mutans
streptococci, yeasts and lactobacilli
showed significant reductions after
3 and 19 months and not surprisingly,
there was no initiation of carious lesions
on these cervical surfaces during the
19-month period. However, the numbers
of Gram-positive pleomorphic
rods (GPPR)
increased after 3 and 19 months. It
should be noted that GPPR predominate
in all lesions and their numbers fail
to vary between lesions with different
textures. Therefore their numbers seem
to provide an unreliable indication
of the severity of lesions.
The root sealant
provided a long-term seal of the patent
dentin tubules on some of the teeth
as three-dimensional analyses showed
that some sealants were still present
after 19 months. Furthermore, the mean
wear was less than the mean sealant
thickness at the end of the study.
Five increments
of the root sealant were applied to
the cervical dentin surfaces at baseline.
However, the application of the sealant
is in two increments according to the
manufacturers. The reason for the 5-increment
application was to assure that this
novel sealant could be detected both
by the employment of the three dimensional
superposition technique and clinical
assessments. In addition, the average
thickness of each increment was approximately
35 µm at baseline and the average wear on the
sealant was approximately 28
µm
at each month especially in the early
months.
The most widely
accepted evaluation technique is to
use the USPHS criteria to assess gross
changes with restorative materials.10
However, there
is no evaluation of wear of the restoration
surface as a whole. The large amount
of subjectivity involved in scoring
preclude comparisons between
different clinical studies using this
scale. Objective
quantitative results can be obtained by analyses of
three-dimensional coordinate data. It is possible
to determine minimal changes in the
cervical surfaces quantitatively and
visually in terms of computer graphics
with this technique.
Different clinical
trials managing dentine sensitivity
are difficult to compare as these trials
differ in their duration and methodology.
A major problem arises from the variations
in sensitivity assessments. Some studies
report changes in the perceived levels
of discomfort evoked by a "standard"
stimulus such as a 1-second blast
of air. Some studies provide only one
measure of sensitivity, while others
include several different and independent
measures of sensitivity. In this study,
a standard method of air stimulus was
used.
There is a need for the treatment of dentin sensitivity. Therefore, this
paper assessed a novel root sealant,
which contains several constituents
such as fluoride, triclosan and resins.
A double blind clinical study has been
planned to investigate the effect of
the constituents on reducing numbers
of total micro-organisms. In addition,
a control group without any sealant
especially in the same subject on the
opposite quadrant could also be assessed.
In conclusion, there was a significant reduction in sensitivity scores compared
to baseline after 19 months. The protective
sealant was found to be capable of covering
the cervical surface to prevent further
wear. In addition, there was a significant
reduction of some representative caries
associated microorganisms in the overlying
plaque. This new root sealant may then be considered to
provide multiple clinical therapeutic
benefits including reducing and preventing
dentin hypersensitivity.
a. Dentsply, Konstanz, Germany.
b. Kerr, Romulus, WI,
USA.
c. Merlin Mk II 750c,Japand. Renishaw OP2
d. Japane. Bury, Lancs,
UK.
Acknowledgements:
The authors wish to thank Dr. Jovanovski and Mrs.
Zou for their support with the metrological
analyses and Prof Beigthon and Dr. Brailsfrod
for carrying out the microbiological
analyses. The investigation was supported
by Dentsply, European Division, Germany.
Dr. Baysan is Clinical Lecturer, Department
of Restorative Dentistry, at the University
of Birmingham,
School Dentistry, Birmingham,
UK.
Prof. Lynch is Professor of Restorative
Dentistry and Gerodontology, Queen's
University Belfast, Belfast,
Northern Ireland.
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Fig. 4.
Sealant wear
at time points of 3, 6 and 19 months -
Midline profile.
)
was less than the mean sealing thickness
(169
