Role of Salivary Physicochemical and Peptide Levels in Dental Caries among Children: An Original Research.

Introduction: Dental caries is a common oral disease that still needs to be thoroughly evaluated for understanding the pathophysiology. Hence, in our study, we evaluate the physicochemical and the peptide properties of the saliva and their role in dental caries among children. Materials and
Methods: We conducted an observational in vitro study among 100 subjects of age 5-15 years. Decayed, missing, and filled surface (DMFT)/dmft was used to calculate the caries activity. The unstimulated saliva was evaluated for the peptides "LL-37, human neutrophil peptide (HNP) 1-3, and human beta-defensin-3" by ELIZA and for the "pH, buffer, and flow rate" of the saliva. The data thus obtained were analyzed to correlate caries and the salivary physiochemical and peptides using the "linear regression analysis." P < 0.05 was deliberated as significant.
Results: Although no statistically significant variation was seen between low and high caries risk groups and the salivary parameters in our study, we observed a negative correlation of the salivary peptides and caries. For the salivary peptide "HNP1-3," there was a statistically significant variation.
Conclusion: The salivary peptides may be carioprotective. However, further research has to be done to establish the mechanism of the action of these substances against caries. Copyright:

INTRODUCTION

The most common of oral diseases are dental caries. A lot of research is being conducted to prevent caries. Many mechanisms have been proposed that cause caries. To prevent disease, one has to understand the exact underlying pathophysiology. The saliva has been established as one of the factors that influence the initiation of caries.[123] There are many components in the saliva that may prevent the onset of caries. Much research has been focused recently on the immunology of the saliva. Among the antimicrobial peptides of the saliva, the “human beta-defensins (HBDs 1, 2, and 3)” and “human cathelicidin peptide (LL-37)” are gaining popularity.,[4567] The physicochemical properties of the saliva such as the “pH, rate of the salivary flow, and the buffering capacity” are also shown to affect the overall dental health.[67] Hence, in our study, we aim to evaluate these salivary peptides, physiochemical properties, and their role in caries among children.

MATERIALS AND METHODS

We conducted an observational in vitro study. The ethics clearance and the guardian consent were obtained for the study. We included 100 subjects of the age 5–15 years, for the study, after screening for our criteria. We included the subjects who had no systemic conditions that may alter the salivary properties. “Caries activity score (CAS)” was measured as the total of the “decayed, missing, and filled surface (DMFT/dmft)” of the primary and secondary teeth. We divided the children into two groups, with 50 each, as low and high risk (CAS ≤22) or high (CAS >22) groups for caries.

The “unstimulated” saliva (2 ml) was collected according to the guidelines. The saliva thus obtained was centrifuged and stored at −70°C for further analysis. The salivary pH, buffer, flow rate along with the “LL-37, human neutrophil peptide (HNP) 1-3, and HBD-3” were evaluated. The groups were compared for the significant variation, and the correlation of the salivary peptides to the caries activity was done using the “Chi-square” and “linear regression analysis.” The Statistical Package for Social Service (SPSS) version 20 was used for the study, and P < 0.05 was deliberated as significant.

RESULTS

We observed that there was no significant variation of the genders and the age between the groups. The mean age was 8 ± 2.3 years [Table 1]. Seventy percent had mixed dentition in our study, whereas 30% had primary teeth. For the salivary physicochemical properties and the peptides, there was no significant variation for groups, except HNP1–3 (P = 0.022) [Table 1].

Table 1

Various parameters comparison for the caries severity

Salivary parameters	Caries severity		P
	Low	High
Male: female	1:1.2	1:1.1	5.21
Age	8±2.3	7±5.69	2.15
LL-37
Low	13±5.263	11±7.89	0.587
High	10±2.45	6±3.25
HNP 1-3
Low	7±5.296	11±7.81	0.022
High	15±2.58	4±9.24
HBD-3
Low	12±5.896	10±5.89	0.964
High	11±6.45	7±3.75
Buffering capacity
Low	10±4.263	9±7.01	0.321
High	14±2.85	11±3.00
pH
Low	8±7.001	5±7.64	0.954
High	14±1.45	10±3.25
Flow rate
Low	12±5.263	9±1.39	0.354
High	11±2.45	7±9.11

HNP: Human neutrophil peptide, HBD: Human beta-defensin

We observed a negative correlation for the caries activity and all the parameters except LL-37. There was no significant correlation observed for the CAS and the parameters [Table 2].

Table 2

Correlation between the caries activity and the salivary parameters

	Correlation coefficient	P
LL-37	0.021	0.652
HNP 1-3	−0.052	0.258
HBD-3	−0.015	0.147
pH	−0.021	0.357
Buffer	−0.020	0.365
Flow rate	−0.023	0.157

HNP: Human neutrophil peptide, HBD: Human beta-defensin

DISCUSSION

We conducted an in vitro observational study among the gender and age-matched children. Our observations suggest that the salivary peptides are protective and prevent caries. Although no significant correlation was established, we observed a negative relation between caries and the included parameters. This signifies that salivary peptides help in fighting caries causing bacteria. Our observation is in unison with the previous studies.[234567] Acidic pH of the saliva is often seen in high caries individuals. Similar to the study of Animireddy et al.,[1] our study also finds a negative correlation to the CAS to the pH. In a similar study, all the three physicochemical properties of the saliva were found to be lower in the caries group than the normal group.[2] The peptide values of the saliva obtained in our study are different from the other previous studies, and the reason may be due to the ethnic differences and the standardizations. HNP1-3 concentration was statistically significant between the high- and the low-level groups in our study. This is similar to the study of Tayab T et al.[2]

The limitation of our study was that no diet history/oral hygiene practice history was correlated with the caries activity.

CONCLUSION

The salivary peptides such as HBD-3, HNP1-3 are carioprotective along with its physicochemical properties. These peptides may also be used to measure the caries activity. Further studies are suggested to evaluate the significance of the salivary components.

Financial support and sponsorship

Nil.

Conflicts of interest

There are no conflicts of interest.