Comparative Desensitizing Effect of a Toothpaste & Mouthwash- Containing Potassium Nitrate: An
In Vivo & In Vitro Scanning Electron Microscopic Study
Siladitya Sen*, K Meena Ananad and Pratibha P k
Department of Periodontology, Manipal College of Dental Sciences, India
Submission: October 25, 2017; Published: May 21, 2018
*Corresponding author: Siladitya Sen, Department of Periodontology, Manipal College of Dental Sciences, Manipal, India, Email: email@example.com
How to cite this article:Siladitya S, K Meena A, Pratibha P k . Comparative Desensitizing Effect of a Toothpaste & Mouthwash- Containing Potassium Nitrate: An
In Vivo & In Vitro Scanning Electron Microscopic Study. Adv Dent & Oral Health. 2018; 8(5): 555749. DOI: 10.19080/ADOH.2018.08.555749
Potassium Nitrate has been used as a desensitizing agent to treat dentinal hypersensitivity for quite a long time. The effectiveness of a potassium nitrate is evaluated many times in the form of toothpaste. There hasn’t been much study done to evaluate the desensitizing efficacy of potassium nitrate used in the form of mouthwash. Aim of our study was to compare the desensitizing effect of a tooth paste & mouthwash-both containing Potassium Nitrate.
Material & Methods:Thirty patients were assessed using evaporative stimuli and thermal stimuli and tactile stimuli and response was evaluated using Visual Analogue Scale at baseline and after 1 month. The patients were divided into two groups; Group I: fifteen patients who used toothpaste containing 5% potassium nitrate, sodium fluoride, xylitol; Group II: Fifteen patients who used mouthwash containing 3% potassium nitrate, sodium fluoride, xylitol. A total of ten extracted human teeth were collected. Horizontal ground section was done in all the teeth. In five ground section of teeth potassium nitrate containing tooth paste were applied and in five ground sections were shaken vigorously in potassium nitrate mouth rinse. All the ground sections were taken for scanning electron microscopic evaluation.
Result:The results of all the stimulus assessment methods indicated that potassium nitrate toothpaste as well as mouthwash showed statistically significant decrease in the sensitivity score on a Visual Analogue Scale compare to baseline. But, there were no statistically significant differences between the groups, although both were effective in the treatment of hypersensitivity toothpaste showed slightly better result. Scanning electron microscopic analysis result showed that there were partial to complete occlusion of dentinal tubules in toothpaste group. However, no such tubule occlusion effect found in mouthwash group.
Conclusion:Both toothpaste and mouthwash containing potassium nitrate are effective in reducing dentinal hypersensitivity. However toothpaste was having slightly better result.
Dentinal hypersensitivity is a clinical condition originating from exposure of dentinal tissue and characterized by painful sensation after thermal, chemical, mechanical or osmotic stimuli. Clinically it is perceived as an acute, localized, rapidly developing and short duration pain . This painful clinical condition affects 8% to 35% of the population . The incidence of Dentinal Hypersensitivity (DH) reportedly peaks during the third and fourth decades of life .
There are many varied etiologic and predisposing factors related to DH. Removal of enamel, as a result of attrition, abrasion, and erosion, or denudation of the root surface by overlying cementum and periodontal tissue loss, are commonly cited . Exposure of the root surface area may be multifactorial, chronic trauma from tooth brushing, tooth flexure caused by abnormal occlusal loading forces, parafunctional habits, acute and chronic
inflammatory gingival and periodontal diseases, acute trauma,
periodontal surgery, and acidic dietary components are commonly cited as major causes of cervical lesions and DH .
Pain caused by DH can be explained by the widely accepted ‘‘hydrodynamic theory’’ proposed by Braennstroem & Astroem in 1964 . According to this theory, the presence of lesions involving enamel or cementum loss in cervical areas and the consequent opening of dentinal
tubules to the oral environment, under certain stimuli, allow the movement of dentinal fluid inside the tubules, indirectly stimulating the extremities of the pulp nerves, causing the pain sensation. It is also found that open dentinal tubules serve as pathways for diffusive transport of bacterial elements in the oral cavity to the pulp, which may cause a localized inflammatory pulpal response . Histologically, under transmission electron microscope, a sensitive tooth shows widened dentinal tubules,
two times larger than tubules of normal dentin and in greater
number per area compared to a tooth without DH . Although
macroscopically the dentin of a hypersensitive tooth does
not differ from that of a normal tooth, the symptoms suggest
minorinflammation of pulp .
Various strategies have been implicated in the treatment
of DH, including lasers, ions and salts, fluoride iontophoresis,
dentin sealers, periodontal soft tissue grafting, and homeopathic
medications . It is still not possible, however, to reach a
consensus about which techniques represent the gold standard in
the treatment of DH.
Currently, two main approaches are used in the treatment and
prevention of DH: tubular occlusion and blockage of nerve activity.
In the tubular occlusion approach, the tooth is treated with a
physical or chemical agent that forms a layer that mechanically
occludes the dentinal tubules and prevents pulpal fluid flow,
thereby leading to reduction in DH [11,12]. Such treatment
strategies as lasers, dentin sealers, and periodontal soft tissue
grafting work on the same principle. In blockage of nerve activity,
potassium ion tends to concentrate in the interior of the dentinal
tubules, causing a depolarization of the cellular membrane of the
nerve terminal and a refractory period with decreased sensitivity
. Dentifrices containing potassium ions have been shown
by several clinical studies to be effective in reducing dentine
hypersensitivity and the American Dental Association Council
on Dental Therapeutics has granted a Seal of Acceptance to
dentifrices containing 5% potassium nitrate (Council on Dental
Potassium nitrate is used either as a toothpaste as or as a
mouthwash. And, there is always a confusion regarding whether
it is effective when delivered as toothpaste or as a mouthwash.
There has been evidence in literature which shows that both
the formulations have therapeutic potential to alleviate dentinal
hypersensitivity [14,15]. But, the studies which compare the
effectiveness of toothpaste and a mouthwash are few in number.
The present study is designed to compare the effectiveness of
desensitizing toothpaste and a mouthwash, both containing
potassium nitrate for the treatment of dentinal hypersensitivity.
The present study was a randomized clinical trial conducted in
Department of Periodontics (Manipal college of Dental Sciences,
Manipal). Thirty patients were recruited forthe study. Inclusion
criterion was, patients reporting with sensitivity in teeth for
hot, cold, sweet, or sour food / beverages. Exclusion criteriawas
-Subjects with history of treatment for dentin hypersensitivity,
poor periodontal condition, systemic debilitating disease, caries
or restoration in the area of hypersensitivity, allergy to the agents
used in the study, patients with orthodontic appliance, crowns. In
the first visit, oral prophylaxis was given to every patient. Severity
of dentinal hypersensitivity measured, by three different types of
a) Sensitive teeth identified first by tactile method- pulling
a single scratch / stroke by a sharp explorer at the cervical
region of teeth. (Figure 1) Subjects will be asked to rate the
subjective perception of the sensitivity during scratch process
as a score of 0 to 10 (where 0= no pain and 10= unbearable
pain) based on the visual analog scale (VAS) The VAS was
a 10-cm line with the anchor words “no pain” (0 cm) and
“intolerable pain (10 cm)” at the opposite ends.
b) Each participant was asked to place a vertical mark on
the VAS to indicate the intensity of his or her level of sensitivity
after receiving stimuli.
c) Exactly after 10 minutes after the tactile test-Exposing
each teeth to air using (2 way syringe) dental air syringe at 30
psi pressure and 23+/- 3ºc temperature for 1 sec. Syringe kept
1 cm from the tooth and held perpendicularly for 2 seconds.
(Figure 2) After the test subjects asked to rate the subjective
perception of the sensitivity during scratch process as a score
of 0 to 10 ( where 0= no pain and 10= unbearable pain)
d) Five minutes after air blast test freezed cold water
applied to sensitive tooth with help of a disposable syringe for
2 seconds. (Figure 3) Patient’s perception again was recorded
in VAS score values.
After conducting three stimulus test all the 30 patients
were randomly divided in to two groups. Group-A: received
desensitizing toothpaste and Group-B: received desensitizing
mouthwash. Randomization was done by asking patients to pick
up a chit of a paper written either tooth paste or mouthwash. Then
all the patients in both groups undergone through periodontal
examination like bleeding on probing, probing pocket depth and
gingival recession. Ultrasonic scaling given to all the patients in
both group. A common instruction given all patients in both group
that they should use a soft tooth brush and brush in rolling type
of brushing method twice daily for 3 minutes. One additional
instruction given to the patients belong to the mouthwash group
that they should use same old toothpaste and not to use any
desensitizing toothpaste and thirty minutes after brushing they
should take 10 ml. of desensitizing mouthwash and rinse mouth
for 1 minutes and then spit out.
All the patients were recalled exactly after one month and
same three stimulus tests were again carried out and patient’s
perception were recorded in VAS score.
Ten extracted human teeth were collected from department of
maxillofacial surgery. One millimeter thickness horizontal ground
sections were made with the help of coarse diamond grit and
straight micromotor hand piece. (Figure 4 & 5) In five horizontal
tooth section potassium nitrate tooth paste was applied with the
help of paint brush and rest of the five horizontal tooth section
were taken in container filled with potassium nitrate mouthwash
and shaken vigorously to simulate the natural mouth rinsing
action. Then, all the ten horizontal tooth sections were taken for
Scanning Electron Microscopic (SEM) analysis.
In the present study, descriptive statistics are presented
as Mean ± Standard Deviation (SD) based on the 10-cm Visual
Analogue Scale (VAS). Students paired‘t’ test was used to compare
the intergroup variation and independent sample‘t’ test used to
make intergroup variation. Calculations were performed using the
statistical package SPSS (Statistical Program for Social Sciences)
version 16 (SPSS Inc, chigaco) and p< 0.05 was considered to be
28 out of 30 patients completed the study after one month.
Unfortunately two patients belong to mouthwash group did not
for follow up evaluation. There was no incidence of any adverse
reaction to any of the agents used in the study. Result of intergroup
analysis (with the help of independent sample ‘t’ test) showed that
there was no statistical significant difference at the base line as
well as after one month follow up (except with respect to tactile
test toothpaste group showed statistical significant reduction of
VAS score compared to mouthwash group) between two groups
with respect to any of the parameters used in the study (like
tactile, air blast, cold water test or bleeding on probing, pocket
depth, gingival recession) (Table 1).
However, result of intra group analysis (with the help of paired
‘t’ test) showed that both toothpaste and mouthwash making
significant reduction of VAS score in follow up visit compare to
baseline visit (Table 2).
In order to find out which one more efficacious toothpaste
or mouthwash we use independent sample ‘t’ test and we found
with respect to tactile and air blast test toothpaste showed greater
reduction of follow up VAS score compare to baseline VAS score
; however this difference found to be not statistically significant.
But with respect to cold water test toothpaste showed statistically
significant reduction of follow up VAS score compare to baseline
VAS score. In overall with respect all three different stimulus test
toothpaste showed slightly better result than mouthwash (Table
3 & Figure 6). SEM analysis showed that tooth paste containing
potassium nitrate causing partial to complete occlusion of
dentinal tubules, whereas mouth wash group did not showed any
kind tubular occlusion effect (Figure 7-10).
The present study was a randomized clinical trial to evaluate
and compare the efficacy of toothpaste containing 5% potassium
nitrate, sodium fluoride, xylitol and a mouthwash containing 3%
potassium nitrate, sodium fluoride in the treatment of dentinal
The results of the study showed that both desensitizing
toothpaste and mouthwash are effective in reducing sensitivity
within one month evaluation period, despite the different
application procedure. Previous studies have reported that
dentifrices containing potassium ions are effective in reducing
sensitivity [16,17] and the American Dental Association Council
on Dental Therapeuticshas granted its Seal of Acceptance to
dentifrices containing 5% potassium nitrate .
The subjective nature of DH pain makes objective evaluation
of it difficult. In the present study, we found that both mouthwash
and toothpaste were effective in reducing DH, as indicated by
reduction of VAS scores. To determine the participants’ sensitivity
levels in the study, we translated the subjective perception to
tactile, air blast and thermal (cold water) stimuli into objective
data using VAS, which is the most appropriate method to use to
diagnose pain levels . To assess pain, we used more than one
stimulus as recommended by Holland et al. .
Patients were advised to use soft tooth brush. Use of hard tooth
brush many times leads to formation of cervical abrasion; which
ultimately leads to dentinal hypersensitivity. Studies have shown
that use of soft tooth brush exerts less pressure and reduces the
incidence of gingival laceration or cervical abrasion [21,22].
Patients were advised to follow rolling brush technique. Faulty
brushing technique always causes more incidence of cervical
abrasion. Studies have shown that rolling technique is easier for
the patients to learn and has almost equal effectiveness in tooth
In the present study desensitizing toothpaste containing
potassium nitrate showed slightly better result than mouthwash
containing potassium nitrate. It can be explained by result of the
study done by Addy et al.  and Masant Kuroiwa et al. ;
which showed that brushing always has a smearing action, pushing
smear layers within the dentinal tubules and occluding them and
making them less sensitive to stimulus. As it was proven by our
SEM analysis, which clearly showed that in the tooth samples
containing potassium nitrate based tooth paste causing complete
tubular occlusion (Figure 7 & 8).