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ORIGINAL ARTICLE
Year : 2017  |  Volume : 21  |  Issue : 2  |  Page : 102-106  

Comparative scanning electron microscope analysis of diode laser and desensitizing toothpastes for evaluation of efficacy of dentinal tubular occlusion


Department of Periodontology, Kamineni Institute of Dental Sciences, Nalgonda, Telangana, India

Date of Submission12-Jul-2017
Date of Acceptance06-Sep-2017
Date of Web Publication29-Dec-2017

Correspondence Address:
Suryakanth Malgikar
Department of Periodontology, Kamineni Institute of Dental Sciences, Narketpally, Nalgonda - 508 254, Telangana
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/jisp.jisp_153_17

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   Abstract 

Background: The present study aims to evaluate the efficacy of diode laser alone and in combination with desensitizing toothpastes in occluding dentinal tubules (both partially occluded and completely occluded tubules) by scanning electron microscope (SEM). Materials and Methods: Fifty human teeth were extracted, cervical cavities were prepared and etched with 17% ethylenediaminetetraacetic acid, and smear layer was removed to expose the tubules. The teeth were divided into five groups: Group I – Application of NovaMin-formulated toothpaste, Group II – Application of Pro-Argin-formulated toothpaste, Group III – Application of diode laser in noncontact mode, Group IV – NovaMin-formulated toothpaste followed by laser irradiation, and Group V – Pro-Argin-formulated toothpaste followed by laser irradiation. After treatment, quantitative analysis of occluded dentinal tubules was done by SEM analysis. Results: The mean values of percentages of total occlusion of dentinal tubules in Groups I, II, III, IV, and V were 92.73% ± 1.38, 90.67% ± 1.86, 96.57% ± 0.64, 97.3% ± 0.68, and 96.9% ± 6.08, respectively. Addition of diode laser (Groups III, IV, and V) yielded a significant occlusion of the dentinal tubules when compared to desensitizing toothpastes alone (Groups I and II). Conclusion: Diode laser (Group III) has shown more efficacy in occluding dentinal tubules when compared with desensitizing toothpastes which was statistically significant (P < 0.05). Among the five groups, NovaMin + diode laser (Group IV) showed the highest percentage of occluded dentinal tubules.

Keywords: Dentinal hypersensitivity, dentinal tubule occlusion, diode lasers, scanning electron microscope


How to cite this article:
Reddy GV, Akula S, Malgikar S, Babu PR, Reddy GJ, Josephin JJ. Comparative scanning electron microscope analysis of diode laser and desensitizing toothpastes for evaluation of efficacy of dentinal tubular occlusion. J Indian Soc Periodontol 2017;21:102-6

How to cite this URL:
Reddy GV, Akula S, Malgikar S, Babu PR, Reddy GJ, Josephin JJ. Comparative scanning electron microscope analysis of diode laser and desensitizing toothpastes for evaluation of efficacy of dentinal tubular occlusion. J Indian Soc Periodontol [serial online] 2017 [cited 2021 Jun 25];21:102-6. Available from: https://www.jisponline.com/text.asp?2017/21/2/102/217759


   Introduction Top


Dentinal hypersensitivity (DH) is defined as an abnormal response of the exposed vital dentine to thermal, chemical, or tactile stimuli. Pain is acute, nonspontaneous, and of short or long-lasting which appears suddenly at specific location.[1] It occurs most commonly and easy to diagnose with a routine examination.[2] DH mechanism could be explained by a combination of two theories: hydrodynamic theory [3] and neural theory.[4] Various treatments for DH are based on the application of desensitizing agents locally, either at home or professionally by dentist. The permeability of dentinal tubules is decreased by occlusion of dentinal tubules which leads to decrease in the degree of DH.[5]

Various desensitizing agents have been used depending on the mechanism of action, to reduce DH such as dentin adhesive sealers (fluoride varnishes, dentin-bonding agents), agents forming protein precipitates (silver nitrate), agents plugging dentinal tubules (sodium fluoride, stannous fluoride, and bioactive glass), and nerve-desensitizing agents (potassium nitrate and strontium nitrate).[6] Recently, it has been proposed that irradiation of affected teeth with low-output power lasers has significant anti-inflammatory actions. Diode laser generates continuous wave without overheating.[7] The combined effects of various desensitizing agents such as bioactive glass-containing toothpaste and other desensitizing toothpastes with laser have shown reduced discomfort of DH.[8] Hence, the major aim and objective of the present study was to explore the efficacy of diode laser alone and in combination with desensitizing toothpastes (NovaMin and Pro-Argin ) to evaluate dentinal tubule occlusion (both partially occluded [PO] and completely occluded [CO] tubules) under scanning electron microscope (SEM).


   Materials And Methods Top


Sample size

All participants gave informed consent. Ethical clearance was obtained from institutional ethical committee. Fifty extracted teeth were included in the study according to inclusion and exclusion criteria given below.

Inclusion criteria

Teeth which were extracted from individuals aged between 18 and 50 years, for various reasons other than dental caries and who had no history of oral prophylaxis in the past 6 months.

Exclusion criteria

  1. Teeth with dental caries
  2. Teeth with restorations.


Randomization

A simple randomization approach [9] using computer-generated random numbers was employed to assign the extracted teeth in the study to one of the following treatment modalities:

  1. Group I (N) – NovaMin-containing toothpaste
  2. Group II (P) – Pro-Argin -formulated toothpaste
  3. Group III (DL) – Diode laser in noncontact mode for 60 s
  4. Group IV (N + DL) – NovaMin-containing toothpaste followed by laser irradiation
  5. Group V (P + DL) – Pro-Argin -formulated toothpaste followed by laser irradiation.


Laser protocol

Teeth were irradiated with GaAlAs Diode Laser (DENLASE, the Diode Laser Therapy System, from China Daheng Group, Inc.) with 400 μm fiber-optic handpiece at a wavelength of 980 nm, operated at power – 1 W, with a pulse length of 200 μm and pulse interval of 200 μm in noncontact mode for 60 s.

Experimental procedure

After cleaning the extracted teeth, a cavity preparation was done in the cervical region of the tooth with 2-mm round bur in box shape of 2 mm × 2 mm × 2 mm dimension. 17% ethylenediaminetetraacetic acid (EDTA) was applied within the prepared box to remove the smear layer. The teeth received the following treatments:

  1. Group I (N) – EDTA-etched specimens were brushed with NovaMin-containing toothpaste for 6 min twice a day for 7 days
  2. Group II (P) – EDTA-etched specimens were brushed with Pro-Argin -formulated toothpaste for 6 min twice a day for 7 days
  3. Group III (DL) – EDTA-etched specimens were treated with diode laser in noncontact mode for 60 s
  4. Group IV (N + DL) – EDTA-etched specimens were brushed with NovaMin-containing toothpaste for 6 min twice a day followed by laser irradiation
  5. Group V (P + DL) – EDTA-etched specimens were brushed with Pro-Argin -formulated toothpaste for 6 min twice a day followed by laser irradiation.


Artificial saliva (AS) was used as a substitute for saliva in the present study. All specimens from each group were kept in AS [10] at pH 7.4 for 7 days which was replaced every 24 h.

Scanning electron microscope analysis

Specimens which were stored in AS were washed with distilled water and sputter coated with a thin gold layer. Photomicrographs were taken from each specimen surface examined at 5.00 KX magnifications under SEM [Figure 1].
Figure 1: Scanning electron microscope

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Steps involved in SEM study are as follows:

  1. Gold sputtering
  2. Teeth mounted in SEM machine
  3. Vaccumization
  4. Image processing.


The surfaces of the specimens were visualized under SEM of magnification 5.0 KX, and photographs of representative areas were obtained. The total number of tubules, number of open tubules, and number of occluded tubules (both PO and CO tubules) were counted manually in each photograph of all the specimens. In the SEM analysis, the percentages were calculated in the following way: percentage of the total number of occluded tubules (either PO or CO) was obtained by dividing the total number of occluded tubules by the total number of tubules in each photomicrography. This result was then multiplied by 100.

Statistical analysis

Statistical analysis was done using one-way ANOVA test to compare the five study groups. Pairwise comparison of the five study groups (I, II, III, IV, and V) with respect to the total (PO + CO) scores by Tukey's multiple post hoc procedures was made and statistical significance was calculated.


   Results Top


The microphotographic images from the SEM were quantitatively analyzed. There were irregular deposits on the dentine surface in the nontreated group, but most of the dentinal tubules were open [Figure 2]. A smear layer-like coating occluding the dentinal tubules was present in NovaMin-containing toothpaste group [Figure 3]. There was partial and complete occlusion of dentinal tubules in Pro-Argin -containing toothpaste [Figure 4]. In diode laser group, there was melting of dentin and occlusion of dentinal tubules [Figure 5]. The combination of diode laser and desensitizing toothpastes showed both complete and partial occlusion [Figure 6] and [Figure 7]. Among all the groups, the efficacy of occlusion of dentinal tubules in Group IV (N + DL) and Group V (P + DL) was more when compared to the other groups (Groups I, II, and III). Between Groups I and II, Group I (N) was more efficient in occluding dentinal tubules than Group II (P) but was not statistically significant. Laser group (Group III) showed better efficacy when compared to Group I (N) and Group II (P) and was statistically significant (P< 0.05). When laser was combined with desensitizing toothpastes (Groups IV and V), the efficacy of occluding dentinal tubules was more when compared to laser group (Group III) but was not statistically significant. The mean percentage values of all the groups were shown in [Table 1] and [Graph 1].
Figure 2: Open dentinal tubules

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Figure 3: Group I (NovaMin)

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Figure 4: Group II (Pro-Argin™)

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Figure 5: Group III (diode laser)

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Figure 6: Group IV (diode laser + NovaMin)

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Figure 7: Group V (diode laser + Pro-Argin™)

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Table 1: Pairwise comparison of the five study groups (I, II, III, IV, and V) with respect to the total (partially occluded + completely occluded) scores by Tukey's multiple post hoc procedures

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   Discussion Top


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. The present study was designed to evaluate the efficacy of diode laser and bioactive properties of desensitizing toothpastes related to their ability to occlude the dentinal tubules after 7 days following daily brushing. In a transmission electron microscopic study, Yoshiyama et al.[11] concluded that dentinal tubule occlusion may be due to deposition of the intratubular dentin layer or substances in the tubules. The active ingredient of NovaMin-containing toothpaste is calcium sodium phosphosilicate which reacts when exposed to aqueous media and provides calcium and phosphate ions to form a hydroxycarbonate apatite (HCA) with time. This HCA layer physically occludes the dentinal tubules and reduces hypersensitivity.

In an in vitro SEM study, Kulal et al.[12] evaluated and compared the efficacy of three commercially available desensitizing toothpastes. The results of this study showed that there was no occlusion of the dentinal tubules in the control group while nano hydroxyapatite group showed 98.1% tubule occlusion. NovaMin and Pro-Argin groups showed 83.1% and 69.1% tubule occlusion, respectively. In the present study, the percentages of tubules occluded were 92.73% in Group I (NovaMin) and 90.67% in Group II (Pro-Argin ) which were more when compared to the percentages of the above study.

The laser power used in the present study was 1 W which is safer to the pulp and seals the dentinal tubules. Generally, laser powers of 0.8, 1, 1.6, and 2 W seal the dentinal tubules without causing any damage.[13]

In the present in vitro study, SEM analysis for Group III (diode laser) on extracted teeth showed occlusion of almost 96.57% dentinal tubules which indicated that the efficacy of diode laser was more when compared to Groups I (N) and II (P). Alterations in the morphology of dentin irradiated with 980-nm diode laser could be observed by SEM and they depend mainly on the parameters of the laser, including the output power, frequency, and application mode, because these parameters are directly related to the energy transmitted to the dentin. According to the manufacturer (DENLASE, the Diode Laser Therapy System, from China Daheng Group, Inc.,), the power of this device ranges from 0.5–7.0 W. In this study, 1 W, 980-nm diode laser was used.

When the power inputs are increased from 2 to 4 W in the continuous mode, the energy of 980-nm diode laser absorbed by the dentin's mineral content is increased, resulting in melting and crystalline arrangement.[14],[15],[16] In the present study, irradiation with 980-nm diode laser seems to be effective for routine clinical treatment of DH, and 1.0 W is the suitable power parameter due to the rapid sealing of exposed dentinal tubules and its safety on odontoblasts and pulp tissue. However, laser energy should be carefully applied due its adverse thermal effects on the pulp and adjacent structures. Increase in the energy density of laser can increase pulpal space pressure and temperature.[17],[18]

In the studies conducted by Moritz et al.,[19] Lan et al.,[20] and Schwartz, et al.,[21] it was reported that laser in combination with chemical agents such as sodium fluoride and stannous fluoride showed increased effectiveness by >20% when compared to that of laser alone. In the present study, diode laser when used alone or in combination with the desensitizing agents showed better results when compared to desensitizing agents alone and the results were as follows: in Group III (DL), 96.57% dentinal tubules were occluded; in Group V (P + DL), 96.92% dentinal tubules were occluded; and in Group IV (N + DL), 97.33% dentinal tubules were occluded.

In the present study, combination of laser irradiation with desensitizing toothpastes enhanced the treatment effectiveness, i.e., Group IV (N + DL) and Group V (P + DL) showed more percentage of occluded dentinal tubules when compared with Group III (DL).

Among the five groups, Group IV (N + DL) showed the highest percentage of completely occluded dentinal tubules. The results of the present study were limited to physical findings of the change in the dentinal tubules and do not present in vivo differences that may result from the physiological effect of these desensitizing agents. In this study, it has been shown that diode laser and desensitizing toothpastes produce varying degrees of obliteration of tubules at initial application and hence could have differences in reduction in sensitivity based on the type and amount of blockage of tubules. All the five groups produced varying degrees of tubule occlusion in the form of complete and partial occlusion.


   Conclusion Top


Diode laser (Group III) has shown more efficacy in occluding dentinal tubules when compared with desensitizing toothpastes, i.e., NovaMin (Group I) and Pro-Argin (Group II) which was statistically significant.

The efficacy of diode laser when combined with the desensitizing toothpaste (Group IV – NovaMin + diode laser and Group V – Pro-Argin + diode laser) was more when compared to Group III (diode laser) which was not statistically significant. Comparison of percentages of CO tubules among the five groups showed that Group IV (N + DL) showed the highest percentage of CO dentinal tubules.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.

 
   References Top

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    Figures

  [Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7]
 
 
    Tables

  [Table 1]



 

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