Journal of Indian Society of Pedodontics and Preventive Dentistry
Journal of Indian Society of Pedodontics and Preventive Dentistry
                                                   Official journal of the Indian Society of Pedodontics and Preventive Dentistry                           
Year : 2008  |  Volume : 26  |  Issue : 2  |  Page : 74--77

A comparison of salivary calcium, phosphate, and alkaline phosphatase in children with severe, moderate caries, and caries free in Tehran's kindergartens

M Shahrabi1, J Nikfarjam1, A Alikhani1, N Akhoundi2, M Ashtiani2, B Seraj1,  
1 Department of Pedodontics, Dental School, Tehran University, Tehran, Iran
2 Department of Pathology, School of Medicine, Tehran University, Tehran, Iran

Correspondence Address:
B Seraj
Department of Pedodontics , Dental School, Tehran University, Tehran


The most common dental disease in childhood is dental caries. This study was carried out to recognize the components of saliva which are protective factors in children to evaluate and predict caries susceptible and caries resistant individuals. Unstimulated whole saliva was obtained from 75 children aged 3-5 years. They divided into three groups: decayed missing and filled teeth (dmft) > 6 (severe caries), 1 < dmft < 6 (moderate caries), and dmft < 1 (caries free). Unstimulated whole saliva assayed by biochemical methods to determine salivary calcium, inorganic phosphate, and alkaline phosphatase. There was no significant changes in salivary calcium, alkaline to phosphate and alkaline phosphatase activity and their ratio with progress of caries ( P > 0.05 ). Although the results showed that salivary phosphate and alkaline phosphatase in caries free group and calcium in the group with severe caries were somewhat more than those in other groups. Despite of the results of the present study, the relationship between salivary components and caries rate in children remains controversial. So more studies are necessary to achieve some practical criteria for predicting dental caries, recognition of susceptible persons, and finally prevention of caries in children.

How to cite this article:
Shahrabi M, Nikfarjam J, Alikhani A, Akhoundi N, Ashtiani M, Seraj B. A comparison of salivary calcium, phosphate, and alkaline phosphatase in children with severe, moderate caries, and caries free in Tehran's kindergartens.J Indian Soc Pedod Prev Dent 2008;26:74-77

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Shahrabi M, Nikfarjam J, Alikhani A, Akhoundi N, Ashtiani M, Seraj B. A comparison of salivary calcium, phosphate, and alkaline phosphatase in children with severe, moderate caries, and caries free in Tehran's kindergartens. J Indian Soc Pedod Prev Dent [serial online] 2008 [cited 2019 Sep 22 ];26:74-77
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Several investigators have reported variations in the calcium and phosphorous concentrations of dental plaque according to site of collection. [1],[2],[3],[4],[5],[6] These variations have generally followed the pattern of distribution of supragingival calculus and have been attributed to the relationship of the plaque to the orifices of the salivary glands.

In view of these observations, a direct relationship between the calcium and phosphorous concentrations of saliva and plaque would not be unexpected. However, Tatevassian reported no correlation between the composition of resting mixed saliva obtained on waking and the composition of aqueous plaque extract in 40 subjects aged 18-21 years. [7]

Much of the early evidence relating calcium and phosphorous levels in plaque to caries experience is also contradictory. [8]

Dawes and Jenkins suggested that the low susceptibility of lower incisor teeth to caries was related to the higher calcium and phosphorous concentration observed in plaque from this area, compared with plaque from other areas of the mouth. [9] In several later studies, with more standardized recording methods, when the total caries activity of the mouth was assessed and subjects were divided into those showing either high caries activity or low caries activity, significant inverse relationships were found between caries experience and plaque calcium or phosphorous levels. [10],[11],[12],[13]

In most studies, the Decay, Missing, Filling (DMF) index has been used as measure of caries experience, but caries progression is discontinous and hence a caries lesion or filling is an indication of past events and not necessarily of current caries activity. In the study reported by Luma, [14] the subjects were divided on the basis of DMF and caries increment over a one-year period. Low extracellular inorganic phosphouous was found in plaque from caries active individuals compared with low-caries group.

The purpose of the present investigation is to relate the calcium, phosphate, and alkaline phosphatase levels in saliva of several caries, moderate and caries free children selected from Tehran's kindergartens.

 Materials and Methods

Subjects were 75 children between 3 and 5 years which examined clinically by a flashlight, explorer, and mirror. The obtained information from the questionnaire was to eliminate the altered factors such as metabolic disease, Rickets, and deformans osteitis which cause increase the level of alkaline phosphatase activity of serum. [15]

To unify the cases, they were asked about their mother's occupation, residence in 2 years ago, cookies, and snack consumption between meals (at least four times in 24 h), breast milk or formula consumption at least for 2 years and brushing teeth once a day. To unify the fluoride consumption through the water tap, the information was obtained from Tehran water organization.

The clinical diagnosis of dental caries was based on to see an undermined cavity in fissures and the presence of pit on the smooth surfaces. [16] The children were divided into three groups: dmft > 6 severe caries (case), 1 [17]

The measurement of phosphate was done by Ultraviolet (UV) method which measured the optic density of phosphorous in complex of phosphorous and ammonium molibidate in 340 nm wave length. [18]

Alkaline phosphatase was measured by kinetic method. Alkaline phosphatase effects on 4-nitrophenyl phosphate and converts if to yellow 4-nitrophenol which could absorb the light. The absorption of light is proportional with alkaline phosphatase enzyme activity.

Statistical analysis

Summary statistical measures (mean and standard deviation) were calculated for continuous variables. For discrete variables, frequency distributions were studied.

Distribution normality assumptions of calcium, phosphorous, alkaline phosphatase, the proportions of calcium to alkaline, alkaline to phosphorous and calcium to phosphorous variables were assessed by the Kolmogorov-Smirnov test. For comparison of these variables between clinical characteristic, one-way analysis of variance (ANOVA) was used. In some comparisons when normality would not hold, non-parametric Kruskal-Wallis test were used. The effect of age was taken into account using the ANCOVA test. In our discussion, the correlations between every two variables were analyzed with Spearman's correlation. The level of statistical significance was established at P P value > 0.05).

[Figure 1] shows the mean of calcium, phosphorous, alkaline phosphatase, the proportions of calcium to alkaline, alkaline to phosphorous, and calcium to phosphorous in three groups of children [Table 2].

The result of Spearman's correlation test shows there is no statistical relationship between gender, order of birth, number of children in a family, age, mother's, and father's education in three groups ( P value > 0.05) [Figure 2],[Figure 3],[Figure 4 ].


Saliva has an important role to protect the oral health. [16],[19] The sufficient amount of saliva is necessary to protect the oral tissue. [19] The balance between demineralization and remineralization depends on the salivary calcium and phosphate concentration as well as the level of the salivary alkaline phosphatase. [15] This is an important point that the calcium and phosphate should be saturated in saliva to effect on demineralization and remineralization. Conflicting results have been obtained from investigations of calcium and phosphate contents of saliva and their relationship to dental caries. Karshan observed that salivary calcium concentration decreased with increasing caries activity. [20] Ashley found that the salivary calcium increased with decreasing caries activity. [21] Shannon and Feller also found the inverted relationship between parotid saliva and Decay, Missing, Filling Surface (DMFS).[22] On the other hand Turtola in 1978 showed the salivary calcium concentration increased with increasing caries activity. [23] Also Elizarova and Petrovich in 1977 investigated in 4- to 12-year-old children and announced that the calcium level of saliva is higher in children with multiple caries than in children with single caries. [24] This study demonstrates the mean of salivary calcium in children with severe caries in more than the two other groups, but this difference was not significant after statistical analysis which confirms the result of the study of Masamurak et al ., [25] Marray and Shaw,[26] Shafizadeh et al ., [27] Cornejo et al. , [ 28] and Gandhy and Damle [15] investigated the relationship between alkaline phosphatase and inorganic phosphorous with decay, filling, surface and they observed the level of alkaline phosphatase and inorganic phosphorous in rampant caries children was higher than the caries free children. [15],[28] Also Shafizadeh et al . demonstrated the same result. [27] However, Mandel and Karshon, and Ashley and Shaw reported low phosphate in children with high dental caries. [24],[27] Also in Shannons and Feller study, there was an inverted relationship between phosphate level and parotid saliva and DMFT. [22]

In this study, the mean of inorganic phosphate and alkaline phosphatase in caries free group was higher than the other groups, but this difference was not significant after statistical analysis. In Shaw study, [26] the calcium to phosphorous proportion was reported significantly higher in caries free group however in our study there was not any significant difference in calcium to phosphorous, alkaline to phosphorous, and calcium to alkaline proportions.


This study demonstrates no significant difference between calcium, phosphate, alkaline phosphatase, and their proportions also there was no relationship between the other probable factors effect on caries process (such as order of birth, gender) in three groups. Since the proportion of the salivary contents is more important in susceptibility or resistance to dental caries, it is suggested to do more investigation in this field. Also by controlling the definite and probable factors effect on dental caries, the effect of inherent difference between people has been confirmed.


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