Indian Journal of Dental Research

: 2012  |  Volume : 23  |  Issue : 5  |  Page : 628--632

Comparison of some salivary characteristics between children with and without early childhood caries

Ali Bagherian1, Gholamreza Asadikaram2,  
1 Department of Pediatric Dentistry, Dental School, Rafsanjan University of Medical Sciences, Rafsanjan, Kerman, Iran
2 Department of Biochemistry and Physiology Research Center, Kerman University of Medical Sciences, Kerman, Iran

Correspondence Address:
Ali Bagherian
Department of Pediatric Dentistry, Dental School, Rafsanjan University of Medical Sciences, Rafsanjan, Kerman


Background and Aim: Early childhood caries (ECC) is one of the most common chronic childhood diseases. Saliva as a host factor plays an essential role in maintaining the integrity of oral structures. The aim of the present study was to compare resting salivary pH, buffering capacity, and secretory immunoglobulin A (sIgA), calcium, and phosphate concentrations between children with and without ECC. Materials and Methods: In this cross-sectional study, samples of unstimulated saliva of 90 children (45 in ECC group and 45 in caries-free group) were taken with Scully method. The pH and buffering capacity were determined by pH meter. sIgA, calcium, and phosphate concentrations were quantitated with ELISA, CPC photometric, and phosphomolybdate/UV methods. Results: The mean resting salivary pH was significantly higher among children without ECC and the buffering capacity was significantly better among this group (P = 0.002). The mean sIgA concentration was significantly higher among the ECC group (P = 0.015). There were no statistically significant differences between calcium and phosphate concentrations between the two groups. Conclusion: The higher mean resting salivary pH and better buffering capacity found in children without ECC are probably the contributing factors that protect against caries development; but further studies are needed to understand the effects of saliva and its characteristics and components on ECC.

How to cite this article:
Bagherian A, Asadikaram G. Comparison of some salivary characteristics between children with and without early childhood caries.Indian J Dent Res 2012;23:628-632

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Bagherian A, Asadikaram G. Comparison of some salivary characteristics between children with and without early childhood caries. Indian J Dent Res [serial online] 2012 [cited 2019 Dec 8 ];23:628-632
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Full Text

Dental caries is the single most common chronic childhood disease. [1] Despite the general global decrease in dental caries in the past decades, early childhood caries (ECC) remains a major problem in many developing countries and in a few industrialized nations. [2],[3]

The American Academy of Pediatric Dentistry (AAPD) describes ECC as the presence of one or more decayed (noncavitated or cavitated), missing (due to caries), or filled tooth surfaces in any primary tooth in a child 71 months of age or younger. [1] Like other types of caries, ECC is caused by Streptococcus mutans that ferment dietary carbohydrates to produce acid on susceptible teeth, leading to caries over a period of time. The biology of ECC may be changed by several endogenous and exogenous factors, such as immaturity of host defense systems, salivary characteristics, feeding patterns, and the style of oral hygiene care in early childhood. [3],[4] But all children who use dietary fermentable carbohydrate do not develop this form of caries. [5]

In recent years, endogenous factors, such as salivary characteristics and components, have been suggested as predisposing factors in children for development of ECC. [4] Saliva as a host-associated factor plays essential role in preserving the integrity of oral structure that can be summarized into four aspects: Diluting and eliminating sugars and other substances, buffering capacity, balancing demineralization-remineralization, and antimicrobial action. [6],[7]

However, data published about correlation between salivary components and ECC are too limited and have only recently begun to be explored. [4],[8],[9],[10],[11]

Since salivary components and characteristics may change with age [12],[13] and because of the importance of the salivary pH, acid-neutralizing power of saliva, the suspected antibacterial role of some salivary components in the caries processes, and the suggested role of calcium and phosphate in the demineralization-remineralization process, the purpose of this study was to compare salivary pH, buffering capacity, and secretary immunoglobulin A (sIgA), calcium, and phosphate concentration levels between children with and without ECC.

 Materials and Methods

Study design

This is a descriptive cross-sectional study comparing resting salivary pH, buffering capacity, and sIgA, calcium, and phosphate concentration levels in children with and without ECC. The protocol was reviewed and approved by the Medical Research Ethics Committee of Rafsanjan University of Medical Sciences and parents had provided informed, written consent for the voluntary participation of their children.


Only children fulfilling the following conditions were included in the study: Age between 36 and 70 months, no history of definite congenital and genetic problems, parental permission, and being able to expectorate.

The children were selected by a random sampling procedure from the children referred to the Pediatric Department of Rafsanjan Dental School. Forty-five randomly selected ECC (18 girls, 27 boys) and 45 without ECC (17 girls, 28 boys) children matched with respect to age and body mass index [weight (kg)/height (m 2 )] as a criteria for nutrition status [14] were selected to enter the study. The mean age and body mass index (BMI) in ECC and without ECC (caries-free) groups were (60.9 ± 8.8 months, 16.9 ± 5.7 kg/m 2 ) and (59.4 ± 12.09 months, 15.2 ± 3.2 kg/m 2 ), respectively.

Clinical examination

Examination for dental caries was carried out using the dental explorer (Medisporex Ltd. Sailkot, Pakistan) and disposable plane mouth mirror (Atlas Teb Co, Tehran, Iran) for an indirect look at lingual areas of the teeth on the dental chair after cleaning the teeth with cotton rolls, when necessary. This was done by an examiner according to the World Health Organization criteria and methods. [15] The decayed, missing, and filled teeth (dmft) scores for primary teeth were recorded by an assistant on data collection forms. Teeth extracted for trauma reasons were not included in dmft score. Restored teeth with recurrent caries and teeth filled with temporary materials were considered as decayed. White spots were not considered as decayed; radiographs were not taken. Based on dental caries, the subjects were divided into two groups: The caries-free group, whose dmft was zero, and the ECC group.

Collection of the saliva

At the day of saliva sampling (1 day after oral examination) the parents were asked to perform usual oral hygiene procedure after breakfast (1 h 30 min before saliva collection) [10],[16] and during this period children were not permitted to eat or drink. The unstimulated whole saliva was collected in small sterile glass tubes on dental chairs and under resting condition using the method described by Scully. [17] (In this method children were asked to spit in the tubes once a minute for 10 min.) All the samples were collected between 10 and 11 AM. After saliva collection, the tube's caps were closed and stored in the ice box and within 5 min delivered to immunochemistry laboratory.

Immunochemical analysis

Saliva samples were centrifuged (centrifugal force: 1000 g) [16] to remove bacteria and other extraneous material. The supernatant was used for immunochemical assays to measure pH, buffering capacity, and concentration levels of calcium, phosphate, and sIgA.

Salivary pH was determined by means of a pH meter (Methrohm, Herisau, Switzerland), which measured the hydrogen ion concentration. Saliva samples were titrated with 0.1 mol/L hydrochloric acid to evaluate the buffering capacity. Saliva pH changes were measured directly using the same pH meter. Salivary buffering capacities were ranked into one of the following three categories: High buffering capacity (above pH 5.5), medium buffering capacity (from pH 5.5 to 4.5), and low buffering capacity (below pH 4.5). [18]

Total calcium was determined using the CPC photometric method of Gitelman. [19] Calcium ions form a violet complex with cresolphthalein in an alkaline medium. The reaction was measured colorimetrically with photometer CLIMA (RAL co, Barcelona, Spain) at 575 nm. The intensity of the color was directly proportional to the calcium concentration in the sample. Inorganic phosphate was determined using the phosphomolybdate/UV method of Daly and Ertingshausen, [20] which relies on the formation of a UV absorbing complex between phosphorus and molybdate. Inorganic phosphorus reacts with ammonium molybdate in the presence of sulfuric acid to form an unreduced phosphomolybdate complex, which is measured as an end point reaction at 340 nm.

Salivary sIgA level was quantified by ELISA method, [21] using commercial sIgA ELISA Kit (Immunodiagnostik, Benshiem, Germany). Salivary sIgA level was measured by using standard samples with known level of sIgA provided by the manufacturer and expressed as mg/dL. In this study, a microplate-reader multiscan (Labequip LTD, Ontario, Canada) was used to read the samples.

Statistical analysis

All data were statistically analyzed by SPSS-16 software. The independent sample t test, Chi-square test, and Pearson's and Spearman's rho correlation tests were used where applicable; a P value less than 0.05 was considered as statistically significant.


In the ECC group, the mean ± SD of dmft was 9.3 ± 3.6, the minimum of dmft was 3 and the maximum was 20. Since the two groups were matched, there were no statistically significant differences between mean age (P0 = 0.48) and BMI (P = 0.09) in ECC and caries-free groups.

[Table 1] indicates that mean resting salivary pH was significantly higher among without ECC group (P0 = 0.002) and mean sIgA was significantly higher among ECC group (P = 0.015). There were also no significant differences in the mean salivary calcium and phosphate concentrations between the two groups.{Table 1}

[Figure 1] shows the percentage distribution of individuals in three buffering capacity groups. Chi-square test indicated that caries-free group had higher buffering capacity (P0=0.002).{Figure 1}

Also, there were no statistically significant correlations between dmft index in ECC group with pH (Pearson correlation coefficient = −0.083, P = 0.59), sIgA (Pearson correlation coefficient = −0.287, P0 = 0.056), calcium (Pearson correlation coefficient = +0.087, P = 0.57), phosphate (Pearson correlation coefficient = −0.154, P = 0.31), and buffering capacity (Spearman's rho correlation coefficient = +0.20, P = 0.19).


ECC is a major public health problem due to the high prevalence in all areas of the world. [2] Saliva and its components have important roles in protecting the oral structures. [6],[7] Although inappropriate pattern of feeding, oral hygiene care, and S. mutans infection are disease causing, they are not sufficient factors to initiate ECC. Endogenous factors, such as saliva characteristics may be an answer to this question that why some children develop ECC while others do not.

According to the results of this study, the mean resting salivary pH in caries-free group was significantly higher than the ECC group. This is in agreement with the studies by Sinor et al.[22] and Farsi, [23] which have shown that a lower resting salivary pH increases the occurrence of dental caries, but Thaweboon et al.[24] and Cogulu et al.[25] found that salivary pH was similar between the two groups with different caries status. Since the level of pH in the enamel dissolution in caries process needs to fall below the critical pH, [1] the more pH mean of resting saliva in caries-free group certainly needs to fall higher in pH to reach the critical point; and maybe this makes caries initiation become more difficult than for the ECC group.

This study also indicated that the buffering capacity of saliva in the caries-free group was significantly higher than that in the ECC group. Bicarbonate, phosphate, and some proteins are the main buffering components of saliva, [6] which increase pH after pH fall due to the production of acid during carbohydrate metabolism by microorganisms. Theoretically, greater power of saliva to neutralize acidic products in the oral cavity may help to restore pH balance in the caries-free group more efficiently and this is in accordance with the finding of this study; however, several studies have indicated that the buffering capacity could not be a risk indicator of dental caries or that the buffering capacity was similar between the groups with different caries status. [22],[23],[25],[26],[27]

The present study also showed no significant differences between calcium and phosphate concentrations between the two groups. Ashley found that the salivary calcium increased with decreasing caries activity. [28] Elizarova and Petrovich in 1997 investigated in 4 to 12-year-old children and found that the calcium level of saliva is higher in children with multiple caries than in children with single caries. [29] Shahrabi showed that salivary phosphate in caries-free group and calcium in the group with severe caries were somewhat more than those in other groups. [11] But Watanabe et al. indicated that calcium concentration of resting saliva had no relationship to the DMFT. [30] Although the importance of calcium and phosphate precipitation on the tooth surfaces in remineralization process has been known, [6],[27] the concentration of these ions could not be a predictor of caries susceptibility. It has been shown that organic molecules, such as statherin and prolin-rich protein have the ability to inhibit precipitation of calcium and phosphate on the oral structure and although saliva is supersaturated with respect to calcium and phosphate, spontaneous precipitation from saliva to tooth enamel does not normally occur. [27]

To make an association between salivary components and their role in dental caries would be complicated because of the different sampling methods, different criteria for patient groups and different laboratory tests between the studies. Also the level of the salivary components may vary according to salivary flow rate, hormonal factors, emotional factors, etc; [31] and their control is nearly impossible in any study. Salivary flow rate is also an important salivary characteristic that may affect dental caries process but because of the difficulty of its measurement in young children, we have not measured it in this study.

In this study, we also found a significant positive association between the concentration of salivary sIgA and the presence of ECC. De Farias and Bezerra and Al Amoudi et al. observed similar findings in their studies on ECC and SECC. [9],[10] This finding can be explained by the infective nature of ECC and dental caries. Since children with ECC show high amounts of S. mutans in the oral cavity, their immune system responds to the high antigenic load, which leads to a high production of immunoglobulin. In the researcher's opinion, it seems that sIgA might be only a first line of defense but when the force of microorganisms attack is high, more sIgA production cannot help in prevention of disease. But Parkash et al. indicated that children with caries had lower salivary IgA. [32] This study also showed that there was no correlation between salivary sIgA and dmft that is in accordance with Watanabe et al.'s study. [30]

It is completely clear that environmental factors, such as feeding habits, fluoride exposure, and style of oral hygiene care, are important in dental caries process and also may affect some of the salivary characteristics. One of the limitations of this study is that matching children from these aspects is nearly impossible.


The higher mean resting salivary pH and better buffering capacity found in caries-free children are likely contributing factors that protect against caries development.It seems that sIgA might be only a first line of defense but when the force of microorganisms attack is high, more sIgA production cannot help in the prevention of disease.Further studies are needed to understand the effects of saliva and its characteristics and components on ECC.


This study was supported by a grant number from the research center of Rafsanjan University of Medical Sciences (grant number: 9/20/1532).


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