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Table of Contents   
ORIGINAL RESEARCH  
Year : 2022  |  Volume : 33  |  Issue : 3  |  Page : 292-296
Effectiveness of laser fluorescence–based device in detecting the extent of re-mineralisation in primary teeth compared to the conventional method: An In vitro study


1 Department of Pediatric and Preventive Dentistry, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education (MAHE) Manipal, Karnataka, India
2 Department of Dental Materials, Biomaterials and Research Center, Yenepoya Dental College, Mangalore, Karnataka, India
3 Department of Oral Pathology, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education (MAHE) Manipal, Karnataka, India
4 Department of Biochemistry, Kasturba Medical College, Mangalore, Manipal Academy of Higher Education (MAHE) Manipal, Karnataka, India

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Date of Submission05-Jun-2021
Date of Decision31-Aug-2022
Date of Acceptance07-Sep-2022
Date of Web Publication17-Jan-2023
 

   Abstract 


Background: Laser fluorescence (LF)–based clinical device DIAGNOdent™ is at present being used to detect caries. Can the same be used to detect therapeutic remineralisation of early white spot lesions? Aims: To explore the feasibility of using LF-based device in monitoring the changes following remineralisation of demineralised primary teeth. Materials and Method: The sample number for the present experimental in vitro study was 10. The LF based device readings were correlated with surface microhardness (SMH) test values to evaluate its efficiency. SMH analysis was performed using a microhardness tester (Tescol-HT1000AD). All the samples were demineralised, followed by remineralisation using fluoride varnish and pH cycling. The data was analysed using the Statistical Package for the Social Sciences (SPSS) version 17.0 (IBM SPSS®) software. Paired t-test was performed to compare laser fluorescence readings and SMH test result values at baseline, after demineralisation, and after remineralisation. Pearson's correlation was used to compare the relation between the laser fluorescence and SMH test. Results: A good negative correlation was seen between the two methods at the baseline readings even though it was not statistically significant (P = 0.069). A positive correlation between the methods existed following demineralisation which was not significant (P = 0.074). The correlation between the parameters following remineralisation showed a moderate negative correlation but was not significant (P = 0.55). Conclusion: DIAGNOdent™ values at baseline, after demineralisation, and after remineralisation was consistent with SMH values. Thus, DIAGNOdent™ can be explored to provide chairside assistance in identifying remineralisation of white spot lesions.

Keywords: Laser fluorescence, remineralization, surface hardness, white spot lesion

How to cite this article:
Nair MJ, Rao A, Jayaprakash K, Natarajan S, Kumblekar V, Suprabha B S. Effectiveness of laser fluorescence–based device in detecting the extent of re-mineralisation in primary teeth compared to the conventional method: An In vitro study. Indian J Dent Res 2022;33:292-6

How to cite this URL:
Nair MJ, Rao A, Jayaprakash K, Natarajan S, Kumblekar V, Suprabha B S. Effectiveness of laser fluorescence–based device in detecting the extent of re-mineralisation in primary teeth compared to the conventional method: An In vitro study. Indian J Dent Res [serial online] 2022 [cited 2023 Feb 5];33:292-6. Available from: https://www.ijdr.in/text.asp?2022/33/3/292/367883



   Introduction Top


Dental caries is a biofilm mediated diet modulated, behaviour moderated disease with a prevalence rate of over 90% in 3- to 5-year-old children in some countries.[1] The initial lesions of dental caries start as a clinically visible white spot on the enamel surface which may present as opaque rough and porous surface due to loss of minerals or as a smooth and shiny surface having the potential to remineralise. Early diagnosis of white spot lesions and timely intervention using remineralising agents helps in controlling the spread.[2]

Fluoride varnish is one of the effective agents used for the remineralisation of white spot lesions.[3] The early changes of remineralisation are challenging to detect clinically. The use of a chairside device with a digital reading would help assess the remineralisation process. A laser fluorescence (LF)-based device called DIAGNOdent™ is being used to detect caries. It works on the principle that carious dental tissues fluorescence more than healthy tissues when irradiated with light wave of 655 nm wavelength.[4],[5]

The present study aimed to explore the possibilities of using an LF-based device in monitoring the changes following remineralisation of demineralised primary teeth. The LF based device readings were correlated with surface microhardness (SMH) test values to evaluate its efficiency.


   Materials and Method Top


The present experimental in vitro study was initiated after receiving Institutional Ethics Committee approval (IEC Protocol No. 20027). The source of the primary teeth was anonymous, and it cannot be tracked to a particular human subject.

The study was conducted between September 2020 and February 2021 (6 months).

Sample size: Based on the key article,[6] comparing the surface hardness and laser fluorescence readings, the expected standard deviation was 0.6. With an alpha error of 1% and power of 99% and keeping an effective difference to show a clinically significant difference of 0.78, the sample size was calculated to be 10.

Inclusion and exclusion criteria: Ten recently exfoliated and intact primary teeth with no clinical signs of white spot lesions or caries, restorations, stains as observed under magnification were selected for the study.

The teeth were thoroughly washed under running water to remove the extraneous debris, sterilized in 10% formalin for two weeks, and stored in 0.5% chloramine-T solution.[7] The prepared samples were subjected to LF and SMH testing. In the next step, all the samples were subjected to demineralisation to produce early caries-like effect. Remineralisation of the demineralised surface was done using fluoride varnish followed by pH cycling. Post-remineralisation, LF and SMH testing were repeated. The details of the steps are as follows:

Preparation of teeth samples

The teeth were sectioned at the level of cementoenamel junction to remove the remaining roots using high-speed handpiece and diamond bur. The crown of the teeth was then embedded in epoxy resin to expose only 4 × 4 mm of the buccal surface. The resin blocks were then serially numbered from 1 to 10. The exposed buccal surfaces were polished serially using 600–1200 grit silicon carbide paper to provide a flat surface for microhardness testing.[8]

Laser fluorescence testing

A laser fluorescence device called DIAGNOdent™ (KaVo, Biberach, Germany) was used in the study. It was calibrated against a porcelain standard prior to testing the samples. Probe B tip of the DIAGNOdent™ was used to record measurements against each block by a single operator, as per the manufacturer's instructions.

Surface microhardness testing

The surface of the mounted sample was polished with silicone carbide grits of size 180 to 2000 and finally polished with pumice using polishing machine (Almicro –MMP 12, Sr No 13558/0220/5).

SMH analysis was performed using a Vickers microhardness tester (Tescol-HT1000AD) under 50 grams load for 10 seconds. Three indentations were made at 100 micrometre distance from each other and an average was recorded. The prepared samples were stored in distilled water at room temperature.

Demineralising the teeth samples

Demineralisation was initiated by immersing each sample in 25 ml of demineralising solution (0.2% polyacrylic acid or 50% hydroxyapatite [Carbopol C907-BF Goodrich Co.]) at pH 5 for 24 h. Demineralisation in partially saturated polyacrylic acid for 24 hours resulted in early carious-like lesions (area of demineralization).[9] Following demineralization, the samples were thoroughly washed under running water for 30 seconds and stored in distilled water.

Application of fluoride varnish

The samples were dried by gently wiping with a tissue. Two coats of Enamelast (Ultradent Products, South Jordan, Utah, USA) fluoride varnish was applied in the paint-like motion using micro-brush, as per the manufacturer's instructions. Varnish was allowed to dry for four minutes and then subjected to pH cycling.

pH cycling

pH cycling of the samples was done for 10 days.[10] The samples were placed in a remineralising solution (1.5 mmol/l calcium, 0.9 mmol/l phosphate, 150 mmol/l KCl in 0.1 mol/l in TRIS buffer, pH 7.0; 0.05 mg fluoride/ml, 1.1 ml/mm2) for four hours followed by immersing in a demineralising solution (2.0 mmol/l calcium and phosphate in 75 mmol/l acetate buffer, pH 4.7; 0.04 μg fluoride/ml, 2.2 ml/mm2) for two hours to mimic the oral cavity environment. The varnish was then removed with a blade and acetone and then the samples transferred to a new remineralising solution for 18 hours. The samples were washed with deionised water before transferring them to demineralisation/remineralisation solutions. This cycle was repeated for a total of 10 days.

Statistical analysis

The data were analysed using the Statistical Package for the Social Sciences (SPSS) version 17.0 (IBM SPSS®) software. Paired t-test was performed to compare laser fluorescence readings and SMH test result values at baseline, after demineralisation, and after remineralisation. Pearson's correlation was used to compare the relation between the laser fluorescence and SMH test.


   Results Top


[Table 1] shows mean DIAGNOdent™ and SMH readings at baseline, after demineralisation, and after remineralisation and pH cycling. The reading was the least at baseline and maximum in the demineralised samples.
Table 1: Mean DIAGNOdent™ and SMH readings at baseline, after demineralisation, and after remineralisation

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SMH analysis showed a statistically significant difference (P < 0.001) between baseline and after demineralisation, with the surface microhardness decreasing after treatment with demineralising solution. Even though the mean surface microhardness increased after remineralisation as compared to after demineralisation, it remained lower than baseline and the difference was not statistically significant. But the difference between SMH values at baseline and after remineralisation was statistically significant.

DIAGNOdent™ readings increased after demineralisation and showed a statistically significant difference between the baseline and demineralised group. Although there was a decrease in DIAGNOdent™ readings following remineralisation, it was not statistically significant. The difference in DIAGNOdent™ readings between the baseline and after remineralisation was statistically significant [Table 2].
Table 2: Paired t-test to compare the SMH and DIAGNOdent™ readings at baseline, after demineralisation, and after remineralisation and pH cycling

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Pearson's correlation results are given in [Table 3]. A positive correlation means that, as one parameter value increases, the other also increases; and negative correlation means that, as one parameter increases, the other decreases. In the present study, a decrease in DIAGNOdent™ reading and an increase in SMH reading suggests no demineralisation or remineralisation. A good negative correlation (r = −0.595) was seen between the two methods at the baseline readings, though not statistically significant (P = 0.069). There was a positive correlation (r = 0.588) between the parameters following demineralisation, but it was not significant (P = 0.074). The correlation between the parameters following remineralisation shows a moderate negative correlation (r = −0.215) but was not significant (P = 0.55).
Table 3: Pearson's correlation

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   Discussion Top


Dental caries is the outcome of demineralisation that surpasses remineralisation. Demineralisation is characterised by loss of minerals from the enamel leading to change in colour to chalky white, surface roughness, followed by actual cavitation. Conversely, the process of remineralisation is the deposition of calcium, phosphate, and fluoride ions. A variety of remineralising agents are available such as fluorides, casein calcium phosphopeptides, NovaMin®, etc.[11]

Fluoride varnish is one of the professionally applied fluorides that is found to be an effective and safe method for remineralisation. Studies have found a 44.3% reduction in demineralisation with fluoride varnish. The advantage of varnish is that it stays on the enamel for a longer period and has good compliance for application by younger children.[12]

Modern concepts of dental caries management are underpinned by three strategies, namely, identification, prevention, and control. It requires the use of a device for early detection of initial demineralisation and quantification of the same at a very early stage.[13] For effective monitoring of the preventive procedure (remineralisation) also, a device that would detect and quantify remineralisation would be practical.

Early detection of demineralisation can be achieved using newer devices utilising techniques such as quantitative light–induced fluorescence, laser-induced fluorescence, systems based on electric current measurements, etc.[14]

Fluorescence-based systems compare the mineral lost with the sound enamel.[15] Systems that are based on electric current compares the amount of current that is passed through the enamel.[14]

DIAGNOdent™ is a laser-based fluorescence device. It emits infrared light and consists of a photo diode with a long pass filter which acts as a detector absorbing the scattered and short wavelength light and transmitting the long wavelength light fluorescent radiation. The digital display corresponds to the detected fluorescent intensity.[16]

The initiation of dental caries may be detected as distinct changes in the affected dental tissues' optical properties. Healthy tooth structures exhibit very little or no fluorescence, resulting in low readings at the display.[17]

The organic and inorganic dental tissues absorb the infra-red light and the process of remitted fluorescence shows values between 0 and 99 depending on the caries invasion.[17]

Changes in the properties of mineral components like reflection, absorption, etc., affect the LF readings and a different value from a healthy tooth helps in identifying demineralised and carious teeth.[6]

Fluoride varnishes are applied until visible changes of remineralisation are detected clinically. Visual inspection can be inaccurate and lead to misinterpretations. Chairside use of a device with digital scoring can help the clinician contain and stop demineralisation and evaluate the remineralisation process. With this purpose, the present study was designed to evaluate the efficacy of laser fluorescence-based devices for the purpose of estimating remineralisation.

Most of the studies on laser fluorescence-based devices agree that it could be effectively used as a tool for the detection of demineralisation. pH cycling was done in the present study to mimic the dynamics of mineral loss and gain involved in caries process.[18]

The effectiveness of a laser fluorescence–based device in detecting the induced remineralisation after demineralisation of primary teeth was evaluated in the present study by comparing it with a conventional method (SMH analysis) for studying remineralisation.[19]

Vickers SMH analysis was used in our study to measure the SMH as it provides measurable sizes of indentations. Moreover, Vickers indenter is considered to be more accurate with less errors than Knoop indenter.[18] Regarding the SMH analysis, in our study there was a significant decrease in the SMH after demineralisation. Comparing the SMH before and after remineralisation, there was an increase; however this was not statistically significant. Even though the SMH after remineralisation was increased compared to after demineralisation, it was still lower than the baseline SMH measurements. LF values and SMH measurements show an inverse linear relationship throughout the study periods.

Diniz et al., Shi et al.[6] reported that LF devices could not detect small changes in mineral content as there was no significant difference in values after demineralisation from the baseline. But in the present study, the mean LF values significantly increased after demineralisation compared to that of the baseline. This significant increase may be attributed to the rise in the surface porosity after treatment with demineralising solution.

In the present study, the difference between the LF readings at the baseline and after remineralisation was statistically significant. The correlation was moderately good based on Pearson's correlation, although the relation between SMH values and LF readings following remineralisation were not statistically significant.

From the present study, it could be inferred that the LF readings was in consistence to hardness testing readings, showing that laser fluorescence-based devices can be used as an in vitro alternative for evaluation of remineralisation.


   Conclusion Top


DIAGNOdent™ values at baseline, after demineralisation, and after remineralisation were consistent with SMH values. Thus, laser fluorescence-based devices can be explored to provide chairside assistance in identifying remineralisation of white spot lesions.

Limitations

  1. To derive at a precise conclusion for clinical application of DIAGNOdent™ in detecting the remineralisation of white spot lesions in primary teeth, a larger sample size could have been more effective.
  2. DIAGNOdent™ can be further compared with clinically applicable methods of determining remineralisation such as photographic analysis method, etc.[20]


Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.



 
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Panov VE, Damyanova DM. Changes in values measured with DIAGNOdent™ for enamel and dentin of deciduous teeth etched for different time intervals. J IMAB-Annu Proceeding (Scientific Pap) 2014;20:589–91.  Back to cited text no. 17
    
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Chuenarrom C, Benjakul P, Daosodsai P. Effect of indentation load and time on knoop and vickers microhardness tests for enamel and dentin. Mater Res 2009;12:473–6.  Back to cited text no. 19
    
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Cochran JA, Ketley CE, Sanches L, Mamai-Homata E, Oila AM, Arnadóttir IB, et al. A standardized photographic method for evaluating enamel opacities including fluorosis. Community Dent Oral Epidemiol 2004;32(Suppl 1):19-27.  Back to cited text no. 20
    

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Correspondence Address:
Prof. Arathi Rao
Department of Pediatric and Preventive Dentistry, Manipal College of Dental Sciences, Mangalore, Manipal Academy of Higher Education (MAHE), Manipal, Karnataka
India
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Source of Support: None, Conflict of Interest: None


DOI: 10.4103/ijdr.ijdr_546_21

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    Tables

  [Table 1], [Table 2], [Table 3]



 

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