Remineralization Effect of Topical NovaMin Versus Sodium Fluoride (1.1%) on Caries-Like Lesions in Permanent Teeth

Abstract

Objective:

NovaMin, a synthetic mineral composed of calcium, sodium, phosphorous and silica releases deposits of crystalline hydroxyl-carbonate apatite (HCA) structurally similar to tooth mineral composition. The aim of this investigation was to compare the potential remineralization effect of topical NovaMin and Sodium Fluoride gel on caries like lesions in permanent teeth.

Materials and Methods:

A total of 60 sound human freshly extracted teeth were subjected to a pH-cycling protocol. Specimens were randomly assigned to one of the two treatment groups with NovaMin contained dentifrice applied to group 1, while group 2 received a dentifrice containing 1.1% neutral Sodium Fluoride. Pastes were applied five times after the samples received a demineralization from an earlier cariogenic challenge. Specimens were then evaluated by a Surface Micro Hardness test (SMH, 25G, 5s). Post-treatment SMH measurements were conducted and Mann Whitney test was employed for statistical analysis.

Results:

Mean post lesion SMH values were 221.99±26.27 and 224.50±28.64 for the first and second groups, respectively. Post treatment SMH values were 232.52±24.34 for NovaMin and 232.03 ±24.46 for the fluoride group. Two way ANOVA test showed a highly significant difference between the two different treatment protocols (p<0.001).

Conclusion:

NovaMin dentifrice appears to have a greater effect on remineralization of carious-like lesions when compared to that of fluoride containing dentifrice in permanent teeth.

INTRODUCTION

For many years attempts were made to develop products capable of producing a chemical bond to the hard tooth structure in order to prevent them from any caries initiation processes in a manner similar to the natural tooth structure [1–3].

NovaMin is a known component made of bio-active glass particulates with a median size of less than 20 microns.

It has been tested for its effectiveness in remineralizing hard tooth structure while occluding dentinal tubules [4–6].

It is indicated that when NovaMin comes in contact with saliva or any aqueous media, its active ingredient, inorganic chemical calcium sodium phosphor silicate, binds to the tooth surface in order to initiate the remineralization process on the tooth enamel.

This is performed by providing silica, calcium, phosphorous and sodium ions to the tooth structure [7, 8]. A localized transient increase in pH occurs during the initial exposure of the mineral due to the release of sodium. This rise in pH helps the calcium and phosphate to form the NovaMin particles, followed by calcium and phosphorous found in saliva to form a calcium phosphate (ca-p) layer. As the particles’ reaction continues and deposition of calcium phosphate complex takes place, this layer crystalizes into a calcium hydroxyl apatite, also known as hydroxyl carbonate apatite [9, 10]. Likowski et al. [11] indicated that 2.5% and 7.0% w/w bioglass® containing dentifrices could significantly reduce the patient’s pain and sensitivity against stimuli through their daily use. Antibacterial effect of NovaMin tooth paste has beendocumented against several periodontal pathogens. Sodium Ion is released for several days providing a long term re-mineralization potential.[9, 12–15].

Antibacterial effect of NovaMin tooth paste has beendocumented against several periodontal pathogens. Sodium Ion is released for several days providing a long term re-mineralization potential.[9, 12–15].

The antibacterial effect of NovaMin is originated from its sodium and calcium contents followed by its effect on bacterial liquid balance [16–18]. The purpose of this study was to compare the remineralization potency of NovaMin and fluoride tooth pastes when applied on tooth enamel with artificial carious lesions when compared to the same effect from a fluoride gel of 1.1%.

MATERIAL AND METHODS

This in vitro investigation was carried out on 60 sound freshly extracted premolar teeth for orthodontic reason. Samples were stored in normal saline prior to the investigation and initial cleaning and drying process.

Teeth were then thoroughly covered by a layer of nail varnish (Max factor, France) leaving a window of 1x1 mm diameter at the buccal surface enamel open (Fig 2 and 3).

Fig 2.

1x1mm opening at the buccal surface

Fig 3.

Homogenized tooth paste oravive and fluoride solutions

Samples were drowned in 1.5 ml of demineralizing solution for one hour in order to induce an artificial carious lesion on the open surface. Demineralizing solution contained 1.4mM calcium, 0.9 mM phosphorous, 0.5 M acetate buffer and 0.03 ppm fluoride with a pH of 5.

Sample teeth were then assigned randomly to one of the two groups (29 each) after being removed from the demineralizing solution.

All dissolved samples were placed in a different remineralizing solution for 22 hours.

Group I was treated by Oravive revitalizing tooth paste containing calcium sodium phosphosilicate (NovaMin) with a remineralization potential (Fig 2).

Group II was treated with Topex take home care 1.1 neutral sodium fluoride gel (Sultan) containing 0.5% fluoride ion equal to 5000 ppm fluoride, distilled water, glycerin, FD&C Blue E#1 and sweeteners) (Fig 7).

Fig 7.

Mean surface hardness of teeth before and after fluoride and NovaMin have been applied

The demineralization and remineralization cycle was repeated for three times. Surface microhardness of caries like lesions (SMH) were measured using the Vicker’s Micro Hardness device (Stress Duramin, Germany) with the power of 25 grams for 25 seconds (Fig 5) (Metalography laboratory-research and science division, Islamic Azad University, Tehran, Iran).

Fig 5.

Comparing the mean Surface Microhardness between the two media

Samples with artificial carious lesion were covered by artificial saliva to simulate the mouth condition before treatment by reminera-lizing tooth paste.

Artificial saliva contained 2gr/lit methyl-p-hydroxybenzoat, 10gr/lit sodium carboxy methyl celulose, 625gr/lit potassium chloride, 0.059gr/lit Mg Cl2, 6H2O, 0.166gr/lit CaCl2-2H2O, 0.804gr/lit K2HPO4, 0.326gr/lit KH2PO4 in which the added KOH pH was set at 6.75 [11].

Both tooth pastes were prepared in the form of a solution with a mixture of 15 gram paste and 45 ml of deionized water homogenized using a magnetic mixer on a vibrating machine [11].

Samples were immersed in Oravive (Nova-Min) in group I, while teeth in group II were immersed in Topex solution.

Both sample groups were removed from their containers after two minutes in order to initiate the demineralization and remineralization cycles and repeated for 5 days [19].

At the end of the surface treatment, micro-hardness of all lesions in both groups were measured using Vicker’s mi crohardness device.

The distribution of different surface micro-hardness values in both groups were evaluated using Kolmogorov Smirnov test.

Mann Whitney test was then used to evaluate the differences between the mean of micro-hardness measurements. Mann_Whitney test was used to see the changes in the mean of the lesions’ microhardness in both groups. The level of significance was considered at α=0.05.

RESULTS

Based on the results of this in vitro investigation it appears that NovaMin has a higher capability to enhance enamel resistance against caries development by altering its surface microhardness when compared to Topex fluoride tooth paste.

The mean values obtained for post lesion SMH were 221.99±26.27μm and 224.50±28.64μm for group I and II, respectively. Post treatment SMH values were recorded at 232.52±24.34μm for NovaMin and 232.03 ±24.46μm for the fluoride group. Kolmogorov Smirnoff test indicated that both groups did not follow a normal distribution path before and after immersion in both remineralizing solutions (p=0.001 and p=0.031). However the differences in both solutions followed a normal distribution (p=0.200 and p=0.129). Mann Whitney test indicated that there was no significant difference between the surface microhardness measurements of teeth before and after NovaMin or fluoride applications (p=0.326 and p=0.877, respectively).

DISCUSSION

The remineralization effect of NovaMin on artificial caries-like lesions of the human enamel under oral condition could revolutionize many aspects of dental practice especially those related to the development of hard tissue defects and carious lesions.

The result of the current study revealed that a considerable amount of surface microhardness of the enamel is achieved after treatment with fluoride or NovaMin tooth paste. However, it appears that the effect of NovaMin was superior to that of 1.1 percent fluoride tooth paste. This could provide basic and potentially important information for its clinical ramification.

Although the overall result of this study shows increase in the surface hardness of all teeth, this increase was significantly higher in the NovaMin group (p< 0.001).

The pH cycling technique used in this investigation has been recommended to induce caries-like lesions as a routine procedure for demineralization and remineralization of the teeth.

In fact it has been extensively used to study the effect of various tooth pastes to strengthen hard tooth structure in the recent years [9,14,19–22]. Levis et al. (2001) indicated that the calcium containing dentifrices have significantly lower remineralization ability even in the presence of fluoride paste (NaF).

The difference with the current results could be due to the differences in the type of tooth paste used by Levis et al (Sooth RX) [23].

As an artificial carious lesion represents all the histological specifications and criteria of naturally developed caries while it is more homogeneous, it is considered quite reliable for demineralization and remineralization studies. Sound subsurface structure (layer) of artificial caries represents these lesions in a more favorable way for caries studies [14, 19, 21, 24].

Low concentration of fluoride added to demineralizing/remineralizing solutions simulate the oral environment and prevent severe enamel surface destruction [14–19].

Demineralization of the enamel depends on the pH and the amount of calcium and phosphate available in the saliva. Subsaturation accelerates dissolution of hydroxy apatite, therefore enhancing the release of calcium and phosphate ions towards the enamel surface.

Hypersaturation and then precipitation of hydroxyapatite, however, results in enamel surface remineralization [19, 25].

Microhardness evaluation is considered as a reliable and a widely used technique to evaluate remineralization changes of the tooth surface [9, 10]. Although the role of calcium and phosphate ions is well recognized on the demineralization/remineralization of the enamel surface, the inorganic content of saliva should also be considered as an effective factor in this process. Artificial saliva was used in order to simulate the oral condition for releasing the bioactive content of NovaMin into the environment. This condition helps the calcium sodium phosphosilicate bioactive glass to gradually substitute by hydrogen ions. As the process continues, a thick layer full of calcium and phosphate precipitates on the tooth surface with an increased pH of the environment preventing the demineralization process [22,25]. Several earlier studies have varying recommended timings of 90 seconds, 2 or 4 minutes brushing for a sufficiently long and effective tooth paste use. The positive result of this study on increasing surface microhardness of the enamel samples approves the effectiveness of 2 minutes brushing time affected by NovaMin and fluoride tooth paste in each pH cycling [21]. The remineralization effect of NovaMin and its significant increase in surface microhardness found in the present study was in line with several earlier studies when compared to this effect by fluoride tooth paste [5, 12, 13, 17, 20]. Based on the illustrated superior effect of NovaMin on remineralization of the enamel to fluoride tooth paste, NovaMin could be suggested as an effective tooth paste for controlling caries processes especially in caries-sensitive teeth or those suffering from enamel hypoplasia or hyposalivation [10, 18, 26, 27].

Although the result of the present study indicates that NovaMin has significantly increased surface microhardness, combination of both pastes (NovaMin and fluoride) may have a synergic effect on remineralization of the enamel [16,17].

Interestingly, one of the facts in favor of NovaMin is the lack of any hypoplastic spots found on young children’s teeth following the use of conventional tooth pastes [27].

This is usually due to swallowing the paste during daily tooth brushing.

This could be counted as one of the advantages of NovaMin over fluoride containing pastes making it recommendable and safe to be prescribed as a tooth paste of choice for young children.

CONCLUSION

1. Based on the results of this in vitro study both fluoride tooth paste (Sultan) and (Oravive) are effective in remineralization of caries-induced lesions in permanent teeth.

2. NovaMin tooth paste had more remineralization effect on artificial caries in permanent teeth.

3. The difference between the two tested tooth pastes was significant for increase in surface microhardness of the enamel by NovaMin (p=0.005).

Fig 1.

Sample teeth in coded pots for the study groups

Fig 4.

Vicker’s microhardness device

Fig 6.

Samples are drowned in tooth paste solutions

Table 1.

Mean surface micro-hardness measures following a caries like lesion initiation or Fluoride application on teeth surfaces

Groups		No. of Samples	Mean	SD
Primary Microhardness	NovaMin	30	221.99	26.27
	Fluoride	30	224.50	28.64
Secondary Hardness	NovaMin	30	232.52	24.34
	Fluoride	30	232.03	26.46
Differences	NovaMin	30	10.53	4.64
	Fluoride	30	7.52	3.61