|Year : 2016 | Volume
| Issue : 1 | Page : 55-62
Remineralization effect of low-level laser and amorphous sodium–calcium–phosphosilicate paste in teeth with fixed orthodontic appliances
Edith Lara-Carrilloa1, Carlos Doroteo-Chimalb2, Sarai Lopez-Gonzaleza1, Raul A Morales-Luckiec3, Oscar F Olea-Mejiac3, Toshio Kubodera-Itoa1, Carlo E Medina-Solisd4
1 Research Center, Facultad de Odontología, Universidad Autónoma del Estado de , Hidalgo, Mexico
2 Department of Orthodontics, Facultad de Odontología, Universidad Autónoma del Estado de , Hidalgo, Mexico
3 Facultad de Química, Universidad Autónoma del Estado de , Hidalgo, Mexico
4 School of Dentistry, Área Acaémica de Odontología, Instituto de Ciencias de la Salud, Universidad Autónoma del Estado de Hidalgo, Hidalgo, Mexico
|Date of Submission||02-Mar-2016|
|Date of Acceptance||21-Mar-2016|
|Date of Web Publication||26-Jul-2016|
Research Center, Facultad de Odontología, Universidad Autónoma del Estado de México, Paseo Tollocan esq. Jesús Carranza, Colonia Universidad, C.P. 50130 Toluca, Estado de México
Source of Support: None, Conflict of Interest: None
The aim of the present study was to evaluate enamel remineralization with NovaMin (amorphous sodium–calcium–phosphosilicate paste) and low-level laser (LLL) for white spot lesions after orthodontic therapy.
Materials and methods
A total of 20 premolars divided into four groups were submitted to three phases: (i) placement fixed orthodontic appliances; (ii) demineralizing solution; and (iii) remineralization for groups (group A, control; group B, NUPRO Sensodyne with NovaMin; group C, LLL; and group D, NovaMin and LLL). In each stage, elemental analysis (calcium, phosphorus, and sodium) was measured under a scanning electron microscope; the data were tested to find significant differences between mineral changes during phases by using the Bonferroni test and Tukey's test between groups.
Calcium and sodium decreased and phosphorus ions increased in all groups at stage 2. In stage 3, all minerals increased for all the tested groups, recording greater values in group B. Calcium showed a statistically significant difference on comparing stage 1 with stage 2 (P = 0.025) and stage 2 with stage 3 (P = 0.019). On the other hand, using the Bonferroni analysis, phosphorous recorded a significant difference on comparing stage 1 with stage 3 (P = 0.013). Applying Tukey's test, a statistical significant difference between groups A and B was recorded as regards the calcium level (P = 0.004) and the phosphorus level (P = 0.003), which also showed a significant difference between group A and group C (P = 0.052). As regards the sodium distribution, no significant differences were found.
According to the results obtained in the current study, using NUPRO Sensodyne with NovaMin than using LLL proved to be the better treatment for white spot lesions, leading ion incorporation and providing an effective alternative for dental demineralization.
Keywords: laser therapy, NovaMin, tooth demineralization
|How to cite this article:|
Lara-Carrilloa E, Doroteo-Chimalb C, Lopez-Gonzaleza S, Morales-Luckiec RA, Olea-Mejiac OF, Kubodera-Itoa T, Medina-Solisd CE. Remineralization effect of low-level laser and amorphous sodium–calcium–phosphosilicate paste in teeth with fixed orthodontic appliances. Tanta Dent J 2016;13:55-62
|How to cite this URL:|
Lara-Carrilloa E, Doroteo-Chimalb C, Lopez-Gonzaleza S, Morales-Luckiec RA, Olea-Mejiac OF, Kubodera-Itoa T, Medina-Solisd CE. Remineralization effect of low-level laser and amorphous sodium–calcium–phosphosilicate paste in teeth with fixed orthodontic appliances. Tanta Dent J [serial online] 2016 [cited 2017 Jun 22];13:55-62. Available from: http://www.tmj.eg.net/text.asp?2016/13/1/55/186939
| Introduction|| |
An imbalance between pathological and protective factors will result in a rupture of the physiological processes of remineralization and demineralization of the dental structure, favoring the latter. Cariogenic bacteria, fermentable carbohydrates, and salivary dysfunction are scientifically accepted as important pathological factors. Human saliva contains calcium and phosphate ions in supersaturated state and therefore has the potential to remineralize enamel.
However, if acid challenges overcome this physiological remineralization process, alternative therapeutic approaches are necessary to enhance remineralization ,.
Decalcification or the development of white spot lesion (WSL) on the enamel surface is the most important iatrogenic effect of the fixed orthodontic appliance therapy.
From the time fixed orthodontic appliances were introduced, WSLs have become a particular clinical problem that can be attributed to the difficulties for oral hygiene on bonded dental arches and the prolonged plaque accumulation on tooth surfaces ,.
Orthodontic appliances physically alter the microbial environment. Increased proliferation of the facultative bacterial population, including Streptococcus mutans, leads to a decrease in pH, which tips the demineralization–remineralization balance toward mineral loss (demineralization), which in turn can lead to WSL development and eventually to cavitation and caries extending into the dentin,.
While postorthodontic treatment of WSLs differs from their prevention during orthodontic procedures, common interventions include fluoride and calcium phosphate-based remineralizing agents. Although fluoride still remains the cornerstone of modern noninvasive dental caries management, new and emerging methods, which can be used as alternatives to fluoride, have been and are in the process of being developed.
NovaMin is a ceramic material consisting of amorphous sodium–calcium–phosphosilicate, which is highly reactive in water, as a fine particle size powder can physically occlude dentinal tubules. In the aqueous environment of the tooth, sodium ions from the NovaMin particles rapidly exchange with hydrogen cations (in the form of H3O +). This leads to the release of calcium and phosphate (PO43−) ions from the material. A localized, transient increase in pH occurs during the initial exposure of the material because of the sodium release. This increase in pH helps to precipitate the extra calcium and phosphate ions provided by the NovaMin particles to form a precipitated calcium–phosphate layer. As these reactions continue, this layer crystallizes into hydroxycarbonate apatite, which is chemically and structurally equivalent to naturally occurring biological apatite. The combination of the residual NovaMin particles and the newly formed hydroxycarbonate apatite layer physically occludes the dentinal tubules ,,.
Since 1960s, it has been consistently demonstrated that under certain conditions, high-powered lasers can reduce the rate of subsurface demineralization of enamel by altering its crystalline structure, acid solubility, and permeability. Nevertheless, the real mechanisms of caries inhibition by laser remain unclear. Because of their high cost, high-powered lasers are not widely employed in private practice in developing countries. The use of low-level lasers (LLLs) appears to be an appealing alternative, as reports in the literature suggest that when used alone or with topical fluoride they may increase tooth resistance to dental caries ,.
Compared with the evidence on the prevention of WSLs during orthodontic treatment, not much is known regarding their treatment with remineralizing agents after the orthodontic therapy. Therefore, the purpose of the present study was to evaluate enamel remineralization of NovaMin (amorphous sodium–calcium–phosphosilicate) and LLL for the treatment of WSLs after orthodontic treatment.
| Materials and Methods|| |
Tooth selection and sample preparation
In total, 20 human premolars, extracted for orthodontic reasons, were used in the study; these were selected on the basis of the following inclusion criteria: intact buccal enamel with no developmental defects, restorations or fluorosis, absence of any pretreatment chemical agents such as hydrogen peroxide, lack of cracks caused by pressure during extraction, and no caries or WSLs.
All remaining visible soft tissue was removed from the teeth with scalpel no. 12. Teeth were stored in 0.01% thymol solution and distilled water at room temperature until further use .
Teeth were rinsed in deionized water for 30 s to wash off the thymol. The root of each tooth was perforated with carbide fissure bur 701L, using a low-speed turbine. An orthodontic wire (Stainless steel 0.018″; TP Orthodontics, Scottsdale, Arizona, USA) was placed into the root orifice. Subsequently, each tooth was fixed with acrylic to the cap of a polyethylene container to facilitate manipulation of the sample. A different acrylic color was used in each group to facilitate comparison [Figure 1].
|Figure 1: Tooth was fixed with acrylic to the cap of the container to facilitate manipulation.|
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All tooth surfaces, except buccal, were painted with three layers of acid-resistant nail varnish and dried for 24 h. Buccal surface was covered with adhesive tape (3M Transpore Surgical Tape; 3M Unitek, New York, USA) leaving a rectangular window at the site of bonding, which corresponds to the bracket size; this ensured that acid etching was restricted only to the exposed window.
Teeth were divided randomly into four groups, with five teeth each. Treatment groups were assigned as follows: group A, which served as the control group or the group without treatment with remineralizing agents; group B, which was treated with NUPRO Sensodyne (Prophylaxis Paste with NovaMin; Dentsply International, USA); group C, which was treated with LLL (Therapeutic Laser, Dentalaser LV KVT-106UP; Lasertech, Dresden, Germany); and group D, which was treated with NovaMin and LLL. Subsequently, 20 specimens were etched, primed, and bonded (Transbond Plus Self Etching Primer; 3M Unitek) for 3 s according to the manufacturer's indications. After bracket placement (Stainless steel premolar brackets, Edgewise Standard 0.018 Mini Uni Twin; 3M Unitek), excess composite material (Transbond XT Light Cure Adhesive Primer and Paste; 3M Unitek) was removed from around the brackets with an explorer, and then were light cured (Ortholux Luminous; 3M Unitek) for 10 s for each interproximal surface, and finally, adhesive tape was removed.
The specimens were prepared for the first evaluation under a scanning electron microscope (SEM) (INCA Penta FetX3; Oxford Instruments, UK), through which an enamel surface characterization was observed, and the percentage analysis of mineral contents of calcium, sodium, and phosphorus ions were obtained. The coronal segments of each tooth were cut with carbide discs and a low-speed dental handpiece to asses stay parallel to slide base of SEM [Figure 2].
|Figure 2: Specimens were prepared for evaluation under a scanning electron microscope.|
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Second stage: demineralization
Dental crown of the samples were fixed again with acrylic to the cap of the polyethylene container, repeating the process described above. To create the initial injury or demineralization, the four groups were immersed in a demineralizing solution. This solution contained 2.2 mmoll CaCl2, 2.2 mnol/l KH2 PO4, and 0.05 M acetic acid; the pH was adjusted with 1 M KOH to 4.4 .
Teeth were immersed in a demineralizing solution for 96 h at 37°C . This produced initial enamel lesions. The teeth were removed from the solution, washed with deionized water, and dried with oil-free compressed air. The wires were cut and all the samples were analyzed under a SEM, under the same parameters as described for the first stage.
Third stage: remineralization
The remineralizing agents were added to each group by following the manufacturer's instructions:
Group A: without treatment or control.
Group B: the NUPRO Sensodyne with NovaMin paste was applied with a rubber cup to each tooth for 1 min, with oscillatory movements in clockwise direction around the bracket, and were then allowed to stand for 1 min before rinsing; samples were washed with deionized water for 30 s and dried with oil-free compressed air for 30 s.
Group C: the LLL was applied by placing the diode 2 mm to the tooth surface (4000 Hz for 4 min/sample), with an oscillatory motion in clockwise direction.
Group D: the procedure of group B was repeated, and before washing, the LLL application was performed with the same procedure as in group C. Samples were washed with deionized water for 30 s and dried with oil-free compressed air during 30 s.
Then, all groups were submitted to a pH-cycling regimen for 7 days to simulate oral environmental conditions. Each tooth was individually incubated for 6 h at 37°C in 40 ml of demineralizing solution (2.0 mmol/l calcium, 2.0 mmol/l PO4, 0.075 M acetate, pH 4.3) . Teeth were removed from the solution and thoroughly rinsed in deionized water and dried with oil-free compressed air for 30 s. They were then incubated for 17 h at 37°C in 20 ml of remineralizing solution (1.5 mm calcium, PO40.9 mmol/l, 0.15 mmoll KCl, and 20 mmol/l cacodylate regulator, pH 7.0) . pH-cycling regimen was repeated every 24 h for 5 days; for the last 2 days, teeth remained in the mineralizing solution. Both demineralization and remineralization solutions were changed every 96 h during this regimen .
After the completion of pH cycling, teeth were rinsed in deionized water and dried for 30 s with oil-free compressed air. A second application of remineralizing agents, corresponding to each group, was carried out, following the process described above. pH-cycling regimen was repeated. Once the second cycle was finished, samples were kept in deionized water until their examination under a SEM.
Statistical analyses were carried out with SPSS for 20.0 Windows (SPSS Inc., Chicago, Illinois, USA). The normality and homogeneity were checked for each variable. The Bonferroni test was conducted to compare mineral changes at different tested stages, whereas Tukey's test was carried out to compare the mean values of mineral changes for different studied groups. This was established according to the sample size.
| Results|| |
[Table 1] shows the mean values of mineral content obtained from elemental analysis by using a SEM for each tested group.
Comparison between first and second stage
After the second stage, the results indicated a loss of calcium ions ranging from 0.54 to 2.02%, being more pronounced in group B.
Phosphorus ions increased in four groups, from 0.22 to 0.57%, being greater in group D. Sodium ion decreased in three groups except for group A, from 0.02 to 0.05%, being higher in group D. Group A showed an increase of 0.07% compared with baseline measurements ([Table 2]).
Comparison between second and third stage
After the application of remineralizing agents, calcium ions gained an increase in all groups, from 0.14 to 2.85%, with group B showing the highest gain of ions.
As regards the phosphorus ions, an increase was observed in groups A, B, and C, with group B showing the highest increase in group B, with 0.54%, whereas a decrease of 0.02% was observed in group D.
Sodium ions increased in groups B and D, being higher in group D with 0.07%; group C recorded no change and group A had a decrease of 0.02% ([Table 2]).
Comparison between first and third stage
When comparing the mean values of the control group with that of the last on third stage, it was obvious that calcium ions increased in the three experimental groups. Group B showed higher values with 0.83%; whereas in group A there was a decreased of 1.37%.
The phosphorus ion increased in all groups, being highest in group B with 0.76% and least in group A with 0.34%.
There was a decrease of sodium ions in group C of 0.02% and a rise in the remaining three groups; the highest values were recorded in group A ([Table 2]).
According to the Bonferroni analysis, calcium concentration showed a statistically significant difference between stage 1 and stage 2 (P = 0.025), and between stages 2 and 3 (P = 0.019) ([Table 3]).
On comparing calcium distribution, a statistical significant differences between groups A and B was found (P = 0.004) ([Table 4] and [Figure 3]).
While studying the phosphorus concentration, statistically significant differences between stages 1 and 3 were observed (P = 0.013) ([Table 3]).
On comparing the distribution of phosphorus, by using Tukey's test, statistically significant differences between group A and B were detected (P = 0.003) ([Table 4] and [Figure 4]).
According to the Bonferroni analysis, concentration of sodium did not record any statistical differences ([Table 3]).
On comparing the distribution of sodium by using Tukey's test, no statistically significant differences were found ([Table 4] and [Figure 5]).
Scanning electron microscope analysis
To measure the minerals from each sample, a reference zone was established with a magnification of ×400 to have a wide range of evaluation.
The characteristic description of the surface samples is shown for each stage. In the first stage, variety of characteristics was observed on the surfaces of the samples – in some, the enamel prisms were barely visible, and scratches exhibited elements that may represent carbon surface contamination [Figure 6].
|Figure 6: (a) Sample 5 (M5) in group A with scratches on the surface; (b) sample 4 (M4) in group D with highly visible prisms and contaminated surface. ×400 magnification.|
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In [Figure 7] the surface was observed with carbon remnants and enamel prisms in a rough surface with disordered and ordered areas.
|Figure 7: (a) Sample 4 (M4) of the group B; (b) sample 2 (M2) in group C have rough surface and visible prisms; (c) sample 3 (M3) in group C has ordered and clean surface, and visible enamel prisms without erosion. ×400 magnification.|
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At the demineralization stage, a remarkable change was observed in the enamel surface: carbon residues, which indicated contamination of the surface, were removed by the exposure to demineralizing solution; enamel prisms became more visible because of erosion; some samples also presented microfractures on the surface [Figure 8].
|Figure 8: (a) M5 group A; (b) M4 group B; (c) M2 group C; (d) M3 group C; (e) M4 group D after being subjected to demineralizing solution. ×400 magnification.|
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At the remineralization stage, it was observed that the enamel surface prisms were visible, more uniform, and more compact especially in the images of group B and group C [Figure 9].
|Figure 9: (a) M5 group A; (b) M4 group B; (c) M2 group C; (d) M3 group C; (e) M4 group D after being treated with remineralizing agents and cyclic pH. ×400 magnification.|
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| Discussion|| |
During orthodontic treatment, tooth enamel is at a higher risk for caries due to food stagnation caused by the appliances and inadequate oral hygiene . Today, there are many ways to stop or reverse the progression of WSLs: good oral hygiene with fluoride toothpaste , fluoride-releasing orthodontic materials , products such as those containing casein phosphopeptide–amorphous calcium phosphate (CPP–ACP) , nanocomplexes such as carbonate–hydroxyapatite nanocrystals, and calcium sodium phosphosilicate (NovaMin) .
Artificial caries-like lesions of enamel are more homogeneously reproducible than are natural lesions, and thus provide a reliable experimental model . When we artificially create the lesion, clinically observed demineralization of the samples around the fixed appliances is observed as a milky white opaque area on smooth surfaces .
To evaluate the samples under a SEM with a magnification of ×400, after immersing in the demineralizing solution for 96 h, surface erosion was observed in 100% of the samples, which was more visible in some samples than in others, which is in contrast to a study by Queiroz et al. , who evaluated mineral loss after 32 h without erosion of the surface, but with loss of minerals.
O'Reilly and Featherstone  concluded that a significant and measurable mineral loss around fixed appliances can occur only 1 month after beginning the orthodontic treatment, emphasizing that demineralization could not be observed clinically yet, suggesting that the loss of mineral may go undetected by the clinician.
In the current study, it was observed that the tested products may significantly remineralize WSLs. However, this effective remineralization is a variable depending on the conditions in which they are applied.
NUPRO Sensodyne added with NovaMin (group B) showed better results, achieving a remineralization up to 2.85% in calcium, and a significant increase of phosphorus and sodium ions; this corroborates the findings in respect to Vahid Golpayegani et al. , who evaluated the effectiveness of NovaMin with respect to sodium fluoride (1.1%) and found that the NovaMin had a great effect on remineralization of WSLs in permanent teeth.
The evaluation of SEM micrographs allowed us to observe changes in the enamel structure; a visible, remarkable regeneration was observed in most samples of this group, a finding that coincided with those reported by Burwell et al. , who observed the changes made in the adamantine structure, which refers greater regeneration of the enamel prisms after the application of NovaMin.
Another similar study was conducted by Gjorgievska and Nicholson , which compared the effectiveness of NovaMin with Recaldent (CPP–ACP); again, the results favored NovaMin, proving its greater efficacy in enamel prisms regeneration, as shown in the current research.
In their study on the effects of a 960 nm laser diode on the solubility of calcium in tooth enamel, Kato et al.  summarized that calcium by itself can alter the enamel surface, but it does not increases the acid resistance, which means that it does not make the dental surface less susceptible to demineralization, unless a fluoride agent is added.
The results obtained in the third stage of this research were relatively unexpected. This study demonstrated that therapeutic laser by itself is capable of achieving favorable results, obtaining up to 1.02% remineralization of the enamel surface with respect to calcium ion, and a minimum but significant increase in phosphorus and sodium ions.
When both remineralizing agents were used, the result was not as expected; although the results were favorable, they were lower than those obtained for the individual application of each mineralizing agent; this is in contrast to the studies by Vahid Golpayegani et al.  and Narayana et al. , who evaluated the combination of 5% NovaMin with fluoride at a concentration of 1100 ppm and obtained good results as the composition of the agents was not affected with regard to the other.
However, it is noted that the application of NUPRO Sensodyne added with NovaMin was carried out according to the manufacturer's instructions, using a rubber cup of undiluted paste into water. The action of this material results from the interaction with aqueous solutions; when it is introduced in an oral environment, the material releases sodium, calcium, and phosphorus ions; it interacts with the fluid, resulting in the formation of hydroxyapatite crystals in the surface. It is also important to remember that the application of laser releases a certain amount of heat in the treated surface – from 1 to 6°C ; this leads to some degree of drying and, consequently, the elimination of moisture from the paste.
| Conclusion|| |
On the basis of the results of this study in vitro and scientific bases that provide each of the products used, we can conclude that the effect of NUPRO Sensodyne added with NovaMin as mineralizing agent in WSLs increases the remineralization effect by itself compared with the combination with therapeutic laser. Moreover, the therapeutic use of lasers to treat WSLs helps to remineralize the surface by itself, but in a lower percentage.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4], [Figure 5], [Figure 6], [Figure 7], [Figure 8], [Figure 9]
[Table 1], [Table 2], [Table 3], [Table 4]