|Year : 2015 | Volume
| Issue : 2 | Page : 82-86
Comparative assessment of bond strengths of affected dentin, using two different remineralizing solutions with or without lasers: Results of an in vitro pilot study
Shirin P Kshirsagar, Shalini Aggarwal, Pooja R Gupta, Alia Mukhtar
Dr. D. Y. Patil Dental College and Hospital, Pimpri, Pune, Maharashtra, India
|Date of Web Publication||20-Apr-2015|
Shirin P Kshirsagar
Dr. D. Y. Patil Dental College and Hospital, Pimpri, Pune, Maharashtra
Aims: Assessing remineralization and bond strengths of remineralizing agents with or without LASERS. Settings and Design: In vitro pilot study. Materials and Methods: Artificial caries-like lesion was created with 10% citric acid in 50 non carious extracted posterior teeth which were divided into six groups according to treatment: GC Tooth Mousse and Toothmin cream with or without LASER, positive and negative control. Remineralization was done for 5 min every day for 7 days. Microhardness test was repeated. Pulsed Nd:YAG Laser (1.064 çm wavelength) was used with a focused beam at 1W and 15 Hz for 10 s on exposed dentin surface. Samples were etched with etching gel for 15 s and rinsed with water for 30 s. Bonding composite restoration of 4 mm height was done with Mylar Strip. Tensile bond strength was calculated. Statistical Analysis: Student's paired t-test evaluated difference between mean values of microhardness. Student's unpaired t-test evaluated the difference between mean values of bond strengths between groups. Results: Significant difference in microhardness in HV (50 g load) was seen in all groups (P < 0.05 for all). LASER Toothmin groups showed the highest increase (311.17%) in microhardness in HV (50 g load) as compared to other groups (GC-255.11%, LASER GC-255.42%, Toothmin 250.34%). Shear bond strength of the LASER-treated Toothmin was significantly higher compared to other groups (P = 0.0021). Conclusions: Toothmin and GC Mousse with or without LASER were found to be effective in increasing mineralization. Bond strength of Toothmin with LASER treatment was higher compared to others.
Keywords: Bond strength, laser, microhardness, remineralization
|How to cite this article:|
Kshirsagar SP, Aggarwal S, Gupta PR, Mukhtar A. Comparative assessment of bond strengths of affected dentin, using two different remineralizing solutions with or without lasers: Results of an in vitro pilot study. SRM J Res Dent Sci 2015;6:82-6
|How to cite this URL:|
Kshirsagar SP, Aggarwal S, Gupta PR, Mukhtar A. Comparative assessment of bond strengths of affected dentin, using two different remineralizing solutions with or without lasers: Results of an in vitro pilot study. SRM J Res Dent Sci [serial online] 2015 [cited 2020 Aug 13];6:82-6. Available from: http://www.srmjrds.in/text.asp?2015/6/2/82/155461
| Introduction|| |
Dental caries is a common clinical problem. Despite several researches in various aspects of the dental caries, efforts of prevention have been only partially successful.  Reduced pH is a known risk factor for demineralization of teeth  and duration of the decrease in pH is an important factor in the development of caries.  There has been a significant progress in controlling the demineralization process using non operative procedures. Remineralisation treatment has received significant attention in this field. A remineralizing agent can increase microhardness of bleached enamel.  Similarly, CO 2 laser irradiation could also be useful for increasing resistance to artificial caries-like formation by sufficiently melting and solidifying the enamel and dentin surfaces.  However, comparative studies of mineralizing agents assessing the bond strengths of affected dentin with laser are not available.
| Materials and Methods|| |
A comparative in vitro pilot study was performed to assess the remineralization and bond strengths of affected dentin using two different remineralizing solutions with or without lasers. Fifty noncarious extracted posterior teeth were [Figure 1] cleaned with the ultrasonic scaler unit and stored in 10% formalin solution in sample collecting beaker until use.
Enamel of the occlusal surface was removed till the dentin surface was exposed. The coronal portion of the crown was removed with a carborundum disk to expose the underlying dentin. The dentin was smoothened with fine grit polishing disk. Using the light body impression material around the metal mold the impression material mold was made to mount the teeth in cold cure acrylic. The samples were kept inverted on the glass slab at the center of mold. The cold cure acrylic was added by sprinkling around the tooth. The sample was mounted in cold cure acrylic such that only the dentin part was visible. Afterward, 45 samples were kept in 10% citric acid solution for 4 h to replicate affected dentin, that is, to simulate the caries-like lesion. Four hours later, teeth were stored in distilled water. Microhardness test was carried out for all the dentin samples using Microhardness Tester, Reichert Austria make, Sr. No. 363798 and Knoop's hardness number was recorded for each sample. The two remineralizing agents used were Recaldent™ (GC Tooth Mousse; [Figure 2]) and Toothmin Tooth Cream (Abbott Healthcare Pvt., Ltd., Mumbai, India; [Figure 2]). These samples were divided into six groups according to the treatment: Group 1 (n = 10) - remineralisation using GC Tooth Mousse [Figure 3]; Group 2 (n = 10) - remineralization using Toothmin Tooth Cream [Figure 3]; Group 3 (n = 10) - remineralization using GC Tooth Mousse followed by LASER; Group 4 (n = 10) - remineralization using Toothmin Tooth Cream followed by LASER; Group 5 (positive control: n = 5) - samples with exposed dentin but not demineralized, etched and bonded; Group 6 (negative control: n = 5) - sample with demineralized dentin were neither remineralized nor LASER treated.
All the samples were demineralized for 5 min every day for 7 days with demineralizing solution. The remineralizing agent was applied with applicator tip over all exposed dentin samples. After 5 min, the remineralizing agent was removed with the help of copious saline irrigation and again stored in the distilled water. In order to confirm remineralization, microhardness test was again carried out on all the demineralized samples. Vicker's Hardness number was recorded with microhardness testing machine (Microhardness Tester, Reichert Austria make). The samples of the fifth group were not demineralized, and the samples of the sixth group were only demineralized but not remineralized. After these half of the remineralized samples from each group were treated with Nd:YAG Laser ([Figure 4]; Fotona, EU). A pulsed Nd:YAG Laser emitted at 1.064 यm wavelength was used in the study. Irradiation was performed with a focused beam at the parameters of 1W and 15 Hz for 10 s on the exposed dentin surface. Two cycles were performed for each sample. All the samples from each group were then etched with etching gel (prime dental) which contained 37% phosphoric acid. Etching was done for 15 s and rinsed with water for 30 s. The rinsed samples were air dried, blotted for 10 s and bonded (Adper™ single bond 2, 3M ESPE). After bonding a composite restoration (Filtek™ Z 250, 3M ESPM) of 4 mm in height was done with the help of Mylar Strip (4 mm in width). Tensile bond strength between the tooth and the composite was calculated for each sample using Universal Testing Machine Instron.
Mean and standard deviation of microhardness in HV (50 g Load) was calculated for positive and negative control groups. Statistical software namely SYSTAT version 12 (by Cranes Software, Bengaluru, Karnataka, India) was used for analysis. Student's Paired t-test was applied to evaluate the difference between mean values of microhardness in HV (50 g load) from demineralization to remineralization in all groups. Percentage increase in remineralization was calculated for all groups. Student's unpaired t-test was applied for evaluating the difference between mean values of Shear Bond Strength (Mpa) between different groups.
| Results|| |
Distribution of mean microhardness in HV (50 g Load) in positive and negative control groups is given in [Table 1]. Significant difference between mean values of microhardness in HV (50 g Load) from demineralization to remineralization was seen in all groups [Table 2].
|Table 1: Microhardness in HV (50 g load) in positive and negative control groups|
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|Table 2: Microhardness in HV (50 g load) from demineralization to remineralization|
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Group treated with Toothmin and LASER showed the highest increase in microhardness in HV (50 g load) as compared to other groups [Figure 5].
Also the mean values of shear bond strength of the LASER treated Toothmin group was highly significant as compared to any other group (P = 0.0021) [Table 3].
| Discussion|| |
Many cycles of demineralization and remineralization occur during the process of lesion development in dental caries. During these pathophysiological events, the caries lesion can be stopped or repaired at early stages with non-operative intervention of increasing the net mineralization. Decreasing effects of cariogenic biofilms and diet, and increasing the efficacy of remineralizing agents can help to achieve this goal.  Excavation of infected dentin and remineralization of affected dentin can help to conserve maximum tooth structure and achieve better dentin thickness. In one of the approaches of remineralization, infected dentin is excavated, cavity filled with the remineralizing solution and sealed for 7 days. It is then restored with the permanent adhesive restoration. In another method, infected dentin is excavated, and cavity is filled with a temporary restoration of which remineralizing agent is one of the components. After the stipulated period of time, the temporary restoration is replaced with permanent adhesive restoration. As the mineral content increases with remineralizing agent, the microhardness of the test surface increases.
GC Tooth Mousse, a water-based, lactose-free cream containing 10% w/w Recaldent casein phosphopeptides-amorphous calcium phosphate (CPP-ACP)  was used for remineralization. CPP-ACP suppresses demineralization and enhances remineralization.  In the oral environment, CPP-ACP binds to biofilms, plaque, bacteria, hydroxyapatite, and soft tissue, localizing bioavailable calcium and phosphate.  It's remineralization potential has been studied in vitro studies. ,
Toothmin, another remineralizing product is based on Anticay technology. Anticay® is a unique technology, commercialized by Biodental Remin, an Australian based biotechnology institute. 
Calcium sucrose phosphate (CaSP-Anticay) has remineralizing potential. CaSP is a mixture of calcium sucrose mono and diphosphate, disucrose monophosphate and inorganic calcium phosphate containing approximately 11% w/w calcium and 7.6% w/w inorganic phosphate.  CaSP decreases tooth enamel demineralization and increases remineralization by the similar mechanism of CPP-ACP. 
An in vitro study has demonstrated that melted smear layer and underlying enamel or dentin degenerated thermally by the heat treatment of Nd:YAG Laser may have a role in increasing resistance to artificial caries-like formation.  However, in vitro studies evaluating an effect of Nd:YAG Laser combined with fluoride sources on the acid resistance of primary tooth enamel after artificial caries induction has shown it to be not more effective than fluoride alone to prevent enamel demineralization. 
In this study, we compared microhardness in HV (50 g Load) between four groups, that is, GC Tooth Mousse, LASER plus GC Tooth Mousse, Toothmin and LASER plus Toothmin. All the four groups showed a significant increase in microhardness (P < 0.01). We observed that the increase in microhardness with LASER treated Toothmin group was highest amongst all the groups.
According to our knowledge, there are no studies which compared the effect of CaSP and CPP-ACP on the bond strength. Ours was an attempt to compare the bond strengths of these two products with or without laser. The bond strength of Toothmin remineralized dentin treated with laser before etching and bonding was significantly higher as compared to other groups. The finding of this in vitro study encourages the use of Toothmin Tooth cream in treatment of affected dentin.
We feel remineralizing solution could be used to avoid unnecessary removal of dentin structure from the tooth surface. Conditioning of the caries affected dentin with Nd:YAG Laser before treating with etchant could help to increase the bond strength between composite and tooth structure.
This study has certain limitations, for instance, it is an in vitro study. The exact process of remineralization occurring in the oral cavity is not possible to replicate in in vitro conditions.
As the remineralization in vitro may be different compared to dynamic complex process occurring in the oral cavity, the results should be carefully extrapolated whilst using in clinical practice. We recommend in vivo studies to confirm these findings. Secondly, the period of remineralization used in this study was 7 days, which may not be sufficient to remineralize caries completely. Based on these results, it is difficult to recommend the exact duration of the application for complete remineralization. Finally, because of the small sample size in each group the extrapolation of results should be done carefully.
| Conclusions|| |
The results of this pilot study show that Toothmin and GC mousse with or without laser were effective in increasing mineralization. Bond strength of Toothmin with LASER was higher compared to other groups.
| Acknowledgments|| |
Authors of this study wish to thank Dr. Anant D. Patil, Plasma Medical Services, Nerul, Navi Mumbai for assistance in editing the manuscript.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5]
[Table 1], [Table 2], [Table 3]