SRM Journal of Research in Dental Sciences

: 2020  |  Volume : 11  |  Issue : 2  |  Page : 72--75

Salivary levels of calcium and phosphorus in children with and without early childhood caries: A pilot study

S Aruna1, B Meenakshi2, KV Rama3, S Valarmathi4,  
1 Department of Pediatric and Preventive Dentistry, Sri Ramachandra Institute of Higher Education & Research, Chennai, Tamil Nadu, India
2 Department of Biochemistry, Tagore Dental College & Hospital, Chennai, Tamil Nadu, India
3 Sophisticated Analytical Instrument Facility, Indian Institute of Technology, Chennai, Tamil Nadu, India
4 Department of Epidemiology, The Dr. Tamil Nadu MGR Medical University, Chennai, Tamil Nadu, India

Correspondence Address:
Dr. S Aruna
Flat 3, Sai Ayush Rameshaa Apts, Plot 190, 4th Street, Murugunagar, Velachery, Chennai - 600 042, Tamil Nadu


Background: The role of saliva in the maintenance of oral health is unequivocal, and its composition influences the dynamics of dental caries by modifying the phases of demineralization and remineralization. Rationale: Dental caries is a dynamic disease characterized by phases of demineralization and remineralization. Remineralization is facilitated by saliva. In children-free from caries, remineralization is dominant, and in caries-active children, demineralization is predominant. Hence, this study has been planned to evaluate the levels of calcium and phosphorus in the saliva which play a significant role in the remineralization process. Objectives: This pilot study was carried out to evaluate the salivary calcium and phosphorus levels of children aged 3–6 years and their possible association with early childhood caries. Materials and Methods: Eighteen children aged 3–6 years were divided into two groups of nine children each – Group I is the caries-free group and children affected with early childhood caries comprising the Group II. Four milliliters of unstimulated whole saliva was collected. The salivary levels of calcium and phosphorus were evaluated using an emission spectrometer – inductively coupled plasma optical emission spectrometer ICP-OES available at Sophisticated Analytical Instrument Facility, Indian Institute of Technology Madras. Descriptive statistics were done. Results: The salivary levels of calcium and phosphorus in children-free from caries were found to be higher than in saliva of children with early childhood caries. Conclusion: More research is needed to elucidate the role of these elements in the prevention of caries.

How to cite this article:
Aruna S, Meenakshi B, Rama K V, Valarmathi S. Salivary levels of calcium and phosphorus in children with and without early childhood caries: A pilot study.SRM J Res Dent Sci 2020;11:72-75

How to cite this URL:
Aruna S, Meenakshi B, Rama K V, Valarmathi S. Salivary levels of calcium and phosphorus in children with and without early childhood caries: A pilot study. SRM J Res Dent Sci [serial online] 2020 [cited 2020 Aug 10 ];11:72-75
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Dental caries, which is characterized by acid demineralization of the calcified tissues of the teeth, is a ubiquitous disease affecting mankind,[1] and when occurring in children <6 years of age, it is referred to as early childhood caries. Despite the global decline of dental caries, early childhood caries remains a major health problem in many developing countries.[2] Dental caries is not a fatal condition but can cause discomfort, pain, swelling, reduced chewing capabilities, affects the body mass index,[3] iron deficiency anemia,[4] loss of school hours, and has an adverse effect on the quality of life of the affected individuals.[4],[5],[6]

Saliva is an exocrine secretion[7] and is one of the most important oral fluids bathing the teeth, and its role in the maintenance of oral health is irrefutable. Although the composition of saliva is primarily aqueous consisting of 99% water, the organic and the inorganic constituents making up the remaining 1% play an essential role in the carious process.[8] Saliva can protect against dental caries from four different aspects such as diluting and eliminating sugars, buffer capacity, antimicrobial action, and balancing demineralization and remineralization.[9]

The integrity of the dental tissues is maintained by saliva by regulating the processes of demineralization and remineralization.[7] The ionic exchanges which characterize posteruptive maturation and remineralization of the incipient carious lesions shift the dynamic balance of dental caries toward remineralization.[7] Thus, salivary levels of calcium and phosphorus may vary inversely with the caries experience.[10] Caries in the primary dentition serves as a predisposing factor for caries in the permanent dentition. The maintenance of oral health in the primary dentition stage is a prerequisite for the maintenance of the permanent dentition in a disease-free state.

Hence, this pilot study was conceived to estimate the salivary levels of calcium and phosphorus in children with and without early childhood caries. The null hypothesis would state that there will not be any difference in the salivary levels of calcium and phosphorus in children with and without early childhood caries.

The novel feature is that the technologically advanced “Inductively coupled plasma optical emission spectrometer” (ICPOES) was used to assess the levels of calcium and phosphorus in saliva. This facilitates accurate data analysis and the assessment of multiple elements simultaneously as compared to absorption spectrometers.

 Materials and Methods

This pilot study was conducted from children (3–6 years of age) who reported to the outpatient department of the department of pedodontics and preventive dentistry of a teaching institution, who were split into two groups of nine patients each based on their caries prevalence.

Group I (nine children – five girls and four boys) – Children without early childhood caries.

Group II (nine children – six girls and three boys) – Children with early childhood caries.

Only participants who were clinically healthy without any positive medical history, with an ability to follow instructions and cooperate, were included into the study. The purpose of the study was explained to the patient and parents/guardians, and informed written consent was obtained before inclusion in this study.

Saliva collection

Participants were refrained from eating or drinking for an hour preceeding sample collection. The time of collection of saliva was from 9.00 am to 10.30 am to minimize the effects of diurnal variation.[11] Four milliliters of unstimulated, expectorated whole salivary samples was collected in clean sterile plastic tubes and was subjected to centrifugation at 3000 rpm for 15 min. To prevent bacterial growth, 0.5 ml of nitric acid was added to the saliva. The supernatant was separated and stored at −20°C in plastic vials for biochemical analysis.

Biochemical analysis

Five milliliters of deionized water was added to the saliva samples before the analysis. The salivary calcium and phosphorus levels were estimated using Perkin Elmer optima 5300 dual viewing ICPOES.[12],[13]

This technologically advanced Spectrometer is available at the Sophisticated Analytical Instrument Facility, Indian Institute of Technology, Madras. A calibration graph was constructed by spiking known standards of calcium and phosphorus in argon plasma operating at 11,000 k. The measurement of calcium was done at 317.933 nm (DL 0.010 ppm) and phosphorus at 213.617 nm (DL 0.076 ppm). The unknown values were obtained by interpolating the emission intensity on the Y-axis to the standard concentration on the X-axis through the graph. A triplicate average result for each element is expressed in parts per million (μg/ml or mg/L).

Statistical analysis

The data were subjected to descriptive statistics using software Epi info version 7 (Centers for Disease Control and Prevention, Atlanta). Since this is a pilot test with a limited number of samples, only descriptive statistics were done, and tests of statistical significance cannot be applied.


The average age of children in the caries-free group is 3.77 years (±1.39), and in the caries-active group was 4.22 years (±0.83). The average decayed missing filled tooth index (dmft) for the caries-active group was 11.77 (±2.77).

The salivary levels of calcium in children with active caries ranged from 18.14 to 54.36 μg/ml with a mean value of 31.26, whereas the calcium in children without caries showed a higher level ranging from 74.58 to 453.00 μg/ml with a mean value of 229.25 μg/ml.

The phosphorus levels in saliva of children with active caries ranged from 5.16 to 127.58 μg/ml with a mean value of 62.45, whereas in children without caries, the phosphorus levels were higher ranging from 9.30 to 143.34 μg/ml with a mean value of 82.72 μg/ml [Table 1].{Table 1}


This pilot study was conducted to assess the salivary levels of calcium and phosphorus in children with early childhood caries in contrast to children who were free from this condition.

Enamel is an acellular tissue composed primarily of hydroxyapatite crystals. The spatial arrangement of these crystals is such that the long axes are parallel to that of the enamel prisms. However, at the boundaries, these hydroxyapatite crystals deviate and produce intercrystalline spaces, which serve as a diffusion pathway for the ions.[1],[14] Dental caries is a complex physicochemical process with the two phases of demineralization and remineralization being interspersed with each other, and although enamel is a dead tissue in the strict biologic sense, its permeability assures that ionic exchange can occur with its immediate environment – saliva and plaque fluids.[14]

During cariogenesis, the organic acids produced by fermentation of carbohydrates diffuse into the tooth through the intercrystalline spaces and result in the dissolution of calcium and phosphate ions from the tooth structure, thus initiating demineralization at the atomic level of the hydroxyapatite crystals.[14],[15] Remineralization is tissue repair, which depends mainly on the precipitation of ions from saliva. The calcium and phosphate ions from saliva and other topical sources can diffuse into the tooth enamel and can strengthen the previously weakened crystals by getting deposited on them.[7]

The levels of calcium were found to be higher in patients who were free from caries as compared to those children with severe early childhood caries. This high calcium concentration in saliva tends to shift the “caries balance” toward remineralization as saliva becomes supersaturated with respect to calcium and phosphate.[16],[17],[18],[19] This is in contrast to the findings of Preethi et al.[20] and Hussein et al.[21] where they found a higher level of calcium in children with early childhood caries.

The saliva of children-free of caries was also found to contain slightly higher levels of phosphorus as compared to children with caries. This is similar to the findings of Shahrabi et al.[10] and Hussein et al.[21] The higher levels of phosphorus may confer cariostatic properties by enhancing the buffering capacity of phosphate in saliva[16],[22] and by maintaining supersaturation of saliva with respect to phosphate ions.[23] Furthermore, phosphate inhibits the growth of bacteria and interferes with the adhesion of pellicle and plaque bacteria to the enamel surface, thus reducing the levels of cariogenic flora and demineralization.

The increased levels of calcium and phosphorus in saliva may serve as the first line of defense against dental caries by promoting remineralization. This has become the primary treatment option of incipient and noncavitated carious lesions and also has given an impetus toward the prevention of dental caries by introducing various remineralizing materials such as casein phosphopeptide–amorphous calcium phosphate (ACP), tricalcium phosphate, bioactive glass, and ACP which act mainly by altering the chemical composition of oral fluids.

Other contributory factors such as diet, feeding habits, oral hygiene, and fluoride levels were not assessed as the composition of saliva is under neuronal control, and the above-mentioned factors directly affect the biofilm.

Dental caries is acid-induced demineralization being mediated by saliva, the composition of which plays a crucial role in maintaining the integrity of the enamel surface. The limitation of this study is the small sample size. Hence, in-depth research with a greater sample size and with the other confounding factors may be useful to elucidate the relationship between the levels of salivary calcium and phosphorus with caries. In future, clinicians can use these parameters of saliva for early detection of caries and thereby counsel their patients toward effective prevention of caries.


The authors would like to thank and gratefully acknowledge Sophisticated Analytical Instrument Facility, Indian Institute of Technology, Madras, for the services and support in using the inductively coupled plasma optical emission spectrometer facility for the analysis of calcium and phosphorus.

Financial support and sponsorship


Conflicts of interest

There are no conflicts of interest.


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