ORIGINAL RESEARCH


https://doi.org/10.5005/jp-journals-10063-0123
CODS Journal of Dentistry
Volume 13 | Issue 2 | Year 2021

An In Vitro Comparison of 5% Potassium Nitrate and 8% Proargin Desensitizing Toothpaste: A Scanning Electron Microscopy Study


Neethu Krishna E1, Shobha Prakash2

1,2Department of Periodontics, College of Dental Sciences, Davanagere, Karnataka, India

Corresponding Author: Neethu Krishna E, Department of Periodontics, College of Dental Sciences, Davanagere, Karnataka, India, Phone: +91 9148376922, e-mail: neethukrishnae@gmail.com

ABSTRACT

Aim: This study is an in vitro comparison of 5% potassium nitrate and 8% arginine that have been applied in the treatment of dentinal hypersensitivity and scanning electron microscopy (SEM) is used to evaluate and compare changes in tubule dimensions after the application of the desensitizing agents.

Materials and methods: A total of 24 disk-shaped dentin specimens were dissected from extracted premolars and molars. Dentin disks of 1 mm were obtained with the help of diamond disks. Eight specimens were randomly selected and allocated to the evaluation groups I (control group), II (5% potassium nitrate), and III (proargin). Each treatment group dentin disk specimen was treated with the respective toothpaste for 2 minutes for a period of 14 days. Each disk was subjected to a pre- and post-treatment SEM analysis to evaluate the changes occurring in the dentinal tubules.

Results: The desensitizing toothpastes showed both complete and partial occlusion of dentinal tubules. There was a statistical significant difference between groups II and III, groups III and I, and groups I and II (p-value < 0.005).

Conclusion: It was concluded that the two desensitizing agents were effective in the dentin tubule occlusion. In addition, efficacy of proargin toothpaste was greater compared to the 5% potassium nitrate containing toothpaste.

How to cite this article: Krishna EN, Prakash S. An In Vitro Comparison of 5% Potassium Nitrate and 8% Proargin Desensitizing Toothpaste: A Scanning Electron Microscopy Study. CODS J Dent 2021;13(2):47-50.

Source of support: Nil

Conflict of interest: None

Keywords: Dentin hypersensitivity, Oral health, Oral hygiene, Scanning electron microscope

INTRODUCTION

Dentinal hypersensitivity is one of the commonly encountered clinical conditions in the day to day dental practice. Dentin hypersensitivity is characterized by a high prevalence of exposed cervical dentin which varies from 8 to 57% which can affect different age groups with the majority of sufferers aged between 20 and 40 years.1 The teeth most commonly involved are maxillary premolars followed by maxillary first molars whereas least affected are the incisors. The most commonly affected site is the buccal aspect of cervical area.2

An ideal dentin hypersensitivity treatment would mimic the natural desensitizing process, inducing changes in dentin that lead to rapid and lasting occlusion of dentin tubules.2 Further, the treatment would be easy to apply, and would have no side effects. Most of the current technologies that deliver rapid occlusion are only available as professionally applied, in-office products. Until now, there has been no toothpaste technology that provides rapid and lasting relief of sensitivity without any adverse effects, such as fluoride incompatibility, poor taste, or staining.2

A breakthrough technology, based upon arginine and calcium carbonate, has been developed and validated for treating sensitive teeth.2 Proargin system is based on the natural process of tubule occlusion. The proargin system consists of arginine, an amino acid which is positively charged at physiological pH, bicarbonate-pH buffer and calcium carbonate act as a source of calcium. The interaction of arginine and calcium carbonate at physiological pH results in the formation of a calcium rich layer which binds to the negatively charged dentin surface resulting in the plugging of dentin tubules and blocking diffusion of fluids. The components maintain the alkaline pH and the resulting glycoprotein formed during the interaction of the components helps in tubule occlusion.1 This technology is unusual in that it can be delivered as a conventional daily-use toothpaste with fluoride, as well as a professionally applied desensitizing treatment for use during periodic prophylaxis procedures.2

This study is an in vitro comparison of 5% potassium nitrate and 8% arginine that have been applied in the treatment of dentinal hypersensitivity and is used to evaluate and compare changes in tubule dimensions after the application of the desensitizing agents.

MATERIALS AND METHODS

Sample size: 24 extracted premolar or molars.

Inclusion criteria:

Exclusion criteria:

Sampling Technique

All the extracted teeth are stored in 10% formalin at room temperature. The teeth are cleaned for debris and tissue. Using plain cut tungsten carbide fissure burs the enamel is removed at high speed under a continuous water spray and crown dentin disks, with a thickness of 1 mm, are prepared by cutting perpendicular to the long axis of tooth using diamond disks. The dentin disks are polished with carborundum paper and are washed with distilled water. Each specimen is etched with 30% phosphoric acid for 15 minutes to remove any smear layer from the grinding process and open the dentin tubules to simulate dentin hypersensitivity. All the disks were stored in distilled water.1 These specimens are grouped randomly into the following groups.

  • Group I: control group: consisted of dentin disks immersed in normal saline (n = 8) (Figs 1A and B).

  • Group II: consisted of dentin disks treated with 5% potassium nitrate (n = 8) (Figs 2A and B).

  • Group III: consisted of dentin disks treated with 8% proargin (n = 8) (Figs 3A and B).

Figs 1 A and B: (A) Pretreatment SEM picture of group I; (B) Post-treatment SEM picture of group I

Figs 2A and B: (A) Pretreatment SEM picture of group II; (B) Post-treatment SEM picture of group II

Figs 3A and B: (A) Pretreatment SEM picture of group III; (B) Post-treatment SEM picture of group III

A pea-sized amount of the assigned dentifrice is placed onto the dentin surface. The brush bristles are at 90° angulation to the specimen and remain in contact with the dentin surface. The brushing duration is for 2 minutes (measured by stopwatch) each day for 14 days. Separate toothbrushes are used for each group.3 After brushing, the specimens are washed and stored in 5% phosphate buffered saline solution. Subsequently, the specimens are dried and prepared for analysis by SEM. The evaluation of dentin occlusion was done based on following criteria4:

  • Type 0: open dentinal tubules without occlusion, that is, acid treated specimens without desensitizing agent application.

  • Type I: partial dentinal tubule occlusion <25% of dentinal tubule orifice.

  • Type II: partial dentinal tubule occlusion of >25% up to 75% of dentinal tubule orifice.

  • Type III: nearly complete dentinal tubule occlusion of >75% of dentinal tubule orifice.

At the time of analysis, type II and type III were considered in the same category as “partial dentinal tubule occlusion.”

Scanning electron microscopy analysis was conducted at Indian Institute of Science, Bengaluru.

Statistical Analysis

The number of tubules evident in each of the 1,500× images was counted to provide a measure of tubule occlusion efficacy. Both the open tubules and the partially occluded tubules were included in the count.

The total number of tubules per square millimeter was calculated using the following formula.5

Total number of tubules per square millimeter = 100,0000 × N/area of photomicrograph in square micrometer

N = number of tubules observed in the specimen.

Descriptive statistical analysis was done by one-way analysis of variance (ANOVA) test to compare the three study groups (Table 1). Pairwise comparison of the groups was done by Tukey’s multiple post hoc test (Table 2).

Table 1: Comparison of efficacy of the desensitizing toothpastes in occluding tubules by one-way ANOVA
Groups Mean number of open tubules Mean number of partially open tubules df p-value
Group I 1795 ± 190 870 ± 550 2 0.05
Group II 329 ± 167 6376 ± 1975
Group III 165 ± 156 1647 ± 984
Table 2: Tukey post hoc test for tubule count data
Group compared Mean difference Standard error Significance
Group I vs II 5505.6 656.6 0.000
Group II vs III 5505.6 656.6 0.000
Group I vs III 776.8 656.6 0.047

RESULTS

The microphotographic images from the SEM were quantitatively analyzed. There were irregular deposits on the dentin surface in the nontreated group, that is, group I, but most of the dentinal tubules were open. A smear layer-like coating occluding the dentinal tubules was present in the other two samples where desensitizing toothpastes were used. The desensitizing toothpastes showed both complete and partial occlusion of dentinal tubules. The mean value of number of occluded dentinal tubules in group II is 1,647 and in group III is 6,376. There was a statistical significant difference between groups II and III, Groups III and I, and groups I and II (p-value < 0.005).

DISCUSSION

In vitro studies on dentinal hypersensitivity encompass use of dentin disks to study dentinal morphology and its interaction with different dental materials. To study dentinal hypersensitivity various methods have been employed, utilizing devices to measure dentin permeability or SEM analysis to estimate dentin reactivity with desensitizing agents.6-8 Studies comparing desensitizing agents in vivo have assessed dentin permeability by measuring fluid movement before and after treatment. Conversely, this equipment which measures the hydraulic conductance is not as easily available as SEM, and also has the disadvantage that samples cannot be reexamined.9,10 Several SEM studies of hypersensitive dentin surfaces have shown that they have tubules that are more patent per unit area and twice as wide when compared to normal nonsensitive dentin.11

The present study was designed to compare the efficacy of 5% potassium nitrate and 8% arginine containing desensitizing toothpastes on dentinal hypersensitivity by occluding the dentinal tubules after 14 days following daily brushing. In a transmission electron microscopic study, Yoshiyama et al. concluded that dentinal tubule occlusion may be due to deposition of the intratubular dentin layer or substances in the tubules.12 In the present study, the tubules treated with the desensitizing agents revealed tubule occlusion while most of the tubules in the control group were found to be open with some of them occluded with a smear layer. Group III which consists of 8% arginine toothpaste showed more effective tubular occlusion compared to group II which consists of 5% potassium nitrate toothpaste.

Although, it was observed that both the toothpastes were able to obtain dentin tubule occlusion, there was statistically significant difference in the tubule occlusion in the dentin disks treated by proargin toothpaste compared to 5% potassium nitrate. The methodology, in particular dentin disk model, was able to quantify the tubule occlusion between the different desensitizing agents. It was also able to provide good statistical data for assessment of the images and elucidation of the efficacy of the desensitizing agents.

In the present study we were able to establish that proargin formula showed better tubule occlusion compared to 5% potassium nitrate. Dentin disk model is a feasible and noninvasive approach to evaluate the efficacy of desensitizing agents and SEM micrographs were able to demonstrate the physical modifications in dentinal tubules. The findings of the present study promote the use of proargin toothpaste for both home application and in office due to low cost and ease of application.

STUDY LIMITATION

The limitation of the study is small sample size and noninclusion of assessment of the hydraulic conductance of dentin. This study is an in vitro study design, hence, limiting its ability to mimic oral health conditions. Since dentinal hypersensitivity is subjective in nature, the results need to be validated against patient’s perception.

CONCLUSION

Within the limits of the study 8% arginine containing toothpaste was found to be more efficient in dentinal tubule occlusion compared to 5% potassium nitrate containing toothpaste. Future researches with larger sample size and in vivo comparison of the clinical efficacy and long term effect of the desensitizing agents with other commercially available agents can be used.

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