Indian Journal of Oral Health and Research

: 2018  |  Volume : 4  |  Issue : 1  |  Page : 6--9

Solubility and water sorption of novel atraumatic restorative treatment materials: A In vitro Study

P Divya Kumari1, S Khijmatgar1, A Chowdhury2, Martin Grootveld3, Edward Lynch4, Chitta R Chowdhury1,  
1 Department of Oral Biology and Genomic Studies, AB Shetty Memorial Institute of Dental Sciences, Nitte (Deemed to be University) Deralakatte, Mangalore, Karnataka, India
2 Global Child Health, King's College London, London, UK
3 Professor of Bioanalytical Chemistry and Chemical Pathology, Health and Life Sciences, Leicester School of Pharmacy, Biomedical & Environmental Health, De Montfort University, The Gateway, Leicester, UK
4 School of Dental Medicine, University of Nevada, Las Vegas, USA

Correspondence Address:
Prof. Chitta R Chowdhury
Head of Department of Oral Biology and Genomic Studies, AB Shetty Memorial Institute of Dental Sciences, Nitte (Deemed to be University), Deralakatte, Mangalore, Karnataka


Objectives: The objective is to determine the solubility (SL) and sorption of novel atraumatic restorative treatment (ART) materials in deionized water or artificial saliva. Materials and Methods: Two compositions of newly developed ART materials were prepared. Individual compositions were prepared separately and placed in 100% humidity at ambient temperature for 24 h. Each was stored in separate vials, either 7 ml of deionized or artificial saliva at ambient temperature for 1, 7, 14, or 28 days. The sorption (S%) and SL% were then determined. Student's t-test was employed to assess the significance level of the differences observed. Results: After 1 day, the mean values for water sorption of the ART-I were 12.1% and ART-II were 16.8% in deionized water (P = 0.01). However, the mean water sorption in artificial saliva for ART-1 was 15.3% and that for ART-II was 18.5% (P = 0.05). The mean SL of ART-I and ART-II was 7.4% and 7.2%, respectively, in deionized water (P = 0.66), and in artificial saliva, it was 7.0% and 6.0%, respectively (P = 0.19). Conclusions: We conclude that water sorption potential of ART-II is more in artificial saliva and SL potential of ART-I was more in deionized water.

How to cite this article:
Kumari P D, Khijmatgar S, Chowdhury A, Grootveld M, Lynch E, Chowdhury CR. Solubility and water sorption of novel atraumatic restorative treatment materials: A In vitro Study.Indian J Oral Health Res 2018;4:6-9

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Kumari P D, Khijmatgar S, Chowdhury A, Grootveld M, Lynch E, Chowdhury CR. Solubility and water sorption of novel atraumatic restorative treatment materials: A In vitro Study. Indian J Oral Health Res [serial online] 2018 [cited 2019 Jan 24 ];4:6-9
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Decayed teeth are often restored with dental cements. The clinical success of such dental cements partly depends on the water solubility (SL) and sorption capacities of the dental materials involved. The SL is the ability of a material to disintegrate which facilitates the release of fluoride ions from the material. The water sorption is the ability of the material to absorb and lose water.[1],[2] Water sorption and SL can cause the disintegration of the material and can, in turn, lead to debonding of the material from the tooth structure which could give rise to the development of dental caries. Dental cements can disintegrate when exposed to natural saliva in the oral cavity, which can be associated with hypersensitivity, pulpal inflammation, and periodontal diseases. Water sorption and SL of cements can give rise to dimensional changes, staining, and marginal leakage affecting flexural strength, Vickers hardness, and mechanical stability. The SL and sorption properties of cements can have significant effects on the clinical outcome. Hence, these two properties should be determined for any newly developed atraumatic restorative treatment (ART) material, as recommended elsewhere.[3],[4],[5]

Therefore, the purpose of this study was to determine the SL and water sorption of newly developed ART materials.

 Materials and Methods

The study was conducted at the Fluoride and Health Division of the Department of Oral Biology and Genomic Studies of A.B. Shetty Memorial Institute of Dental Sciences, Nitte University, Deralakatte Mangalore, India. Two novel ART dental cements were assessed for SL and sorption in artificial saliva as well as deionized water.

The composition of the artificial saliva employed in these studies was calcium chloride (0.111 g), sodium chloride (2.05 g), sodium acetate (2.05 g), and sodium dihydrogen phosphate (0.156 g) and dissolved in a final volume of 1.00 L of deionized water (final pH value 7.00).[6]

Samples of newly developed ART-I (n = 20) and ART-II materials (n = 20) were prepared [Table 1]. Each individual sample incorporated with neem extract was placed in a Teflon mold (with an inner diameter 6 mm and a depth of 3.5 mm) and compressed for 20 min until set. After setting, each specimen was removed from the mold and stored in a closed container at laboratory (ambient) temperature for 24 h, to allow more maturation of the cement.{Table 1}

Further, the ART-I and ART-II materials were divided into two sets with ten numbers each to be tested in deionized water and artificial saliva, respectively. Each specimen of the ART-I and ART-II materials was immersed in individual vial containing 7 ml of deionized water (n = 10 of each) and 7 ml of artificial saliva (n = 10 of each ART material). Each storage media was maintained at pH 7.0. The deionized water and artificial saliva were changed during the period of 1, 7, 14, and 28 days.

The SL and water sorption were determined by recording the initial weight (W1) of samples using a precision weighing scale (Sartorius BSA223S). Immediately after weighing, samples were then stored in the individual vials containing 7.0 ml of the storage medium (deionized water or artificial saliva) at ambient temperature for time period of 1 day. The specimens were removed from their vials and immediately weighed (W2). Thereafter, the samples were dehydrated at 37°C for a full 24 h and then weighed again (W3). The above-mentioned procedure was repeated at the time interval of 7, 14, and 28 days.

The water sorption potential was determined from the difference between the initial and the wet weighing (W2-W1). The loss of material (SL) was obtained from the difference between the initial and final drying weight of each sample (W1-W3).

The percentage of mass change or increase in weight of the specimen (S%) is the apparent value for water sorption by the specimen, and the SL% represents the amount of material lost in the media during each immersion period.

The values of water sorption (S%) and SL%, for each sample tested, were calculated using the following equations:[7]

S% = ([W2-W1]/W1 × 100)

SL% = ([W1-W3]/W1) × 100

The water sorption and SL values of the ART materials were analyzed statistically using SPSS version 20 (IBM Corporation, Armonk, New York, United State). Student's t-test was employed to assess the significance level of the differences observed.


[Table 2] illustrates the mean water sorption of ART-I and ART-II materials in both storage media in different intervals of time. The water sorption of both ART materials was greater in artificial saliva than it was in deionized water [Figure 1] and [Figure 2]. Water sorption of ART-II was significantly more than that of ART-I in both the media (P < 0.05), except during the first 24 h, when the water sorption in artificial saliva was not significantly different (P ≥ 0.05).{Table 2}{Figure 1}{Figure 2}

The mean water SL of ART-I and ART-II is given in [Table 3]. SL of ART-I and ART-II increased with time [Figure 3] and [Figure 4]. The SL of both ART materials was higher in deionized water, although there were no significant differences in the SL of ART-I and ART-II in deionized water at day 1 of immersion in the storage media (P > 0.05).{Table 3}{Figure 3}{Figure 4}


This study revealed that the SL of the novel ART-I and ART-II materials was found to be within the limits of the American Dental Association Specification after 1 week of immersion in deionized water and artificial saliva. In the present study, two new novel compositions were tested in deionized water and in artificial salivary media during a 1–28-day period. As shown in [Figure 1] and [Figure 2], sorption of ART-I and ART-II materials in artificial saliva was higher than that in deionized water. However, SL of both ART-I and ART-II materials in deionized water was higher than that in artificial saliva [Figure 3] and [Figure 4]. Since water is more diffusible than organic solvents, the loss of material during the 1st day was encouraging, as reported elsewhere.[8],[9] ART-II had higher water sorption and less SL when compared to those of ART-I both in deionized water and artificial saliva media. One of the reasons is mechanical properties of ART-II was higher than that of ART-I (data of mechanical properties of ART materials were not included here).

Statistically significant differences for sorption between the ART-I and II materials were evident in both media employed. P values for SL are illustrated in [Table 2]. The SL of ART-I and ART-II was greater on day 1 of immersion in the media than on the remaining experimental time points of the set schedules. In general, the SL of the ART restorative materials was higher on day 1 of immersion in the media used, an observation ascribable to the presence of unbound particles in the ART samples which has also been reported in previous studies.[8],[9]

The present study is static SL which is unrelated to the nonstatic condition of the oral environment. The present study assessed the short-term SL of these ART materials, and similar reports have been published elsewhere.[10],[11]

The present study did not compare the SL and water sorption properties of these ART materials with any marketed one.[9],[12] The sorption and SL of restoring materials can be influenced by numerous variables including the conditions of the test, concentration of the medium, pH of the medium, specimen shape and thickness, and powder/liquid ratio of cement.[7],[8],[13] However, it should be noted that it is difficult to compare the data of sorption and SL with other studies in view of variations in sample size, time periods, and measurement units.[6],[12]

Adequate resistance to dissolution in the oral environment is one of the required properties of an ART material. The mechanical properties of restorative materials are dependent on absorption or dissolution processes, and these critically depend on the durations of exposure.[10],[14]

Both water sorption and SL may cause loss of marginal integrity, changed surface properties, and the esthetics of restorative materials.[13] If a restorative material has higher SL and sorption properties more than specified values, there is a probability of significant dissolution which can affect its longevity in the oral environment. For example, leakages may develop which can lead to a risk of developing secondary caries.[7] Some studies performed to test the behavior of dental cements have used water, acids, and other solvents to simulate the contaminating environment of the mouth, but in our study, we used only deionized water and artificial saliva.[6],[12],[15],[16]

The water sorption measurements actually measured the net gain in weight of a specimen arising from the ingress of water molecules and the egress of monomers and other small molecules. In this study, sorption characteristics of the restorative materials found a difference which needs further evaluation to minimize a confounding issue.[11]

Some novel materials can only dissolve initially and then remain stable, which may not be the same in the oral environment, and further research is, therefore, required for the new ART material.[17],[18]


It can be concluded that ART-II is more resistant to dissolution than the ART-I material. The SL and water sorption for both novel ART materials were found to be within the range of existing ART dental materials.


Statistical analysis was supported by Professor Krishna Bhatt, Department of Statistics of KS Hegde Medical Academy (KSHEMA), Nitte University, Deralakatte, Mangalore, India.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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