Effect of Saliva Composition on Experimental Root Caries

Mass spectrometry-based proteomic approaches for salivary protein biomarkers discovery and dental caries diagnosis: A critical review

Dental caries is a multifactorial chronic disease resulting from the intricate interplay among acid-generating bacteria, fermentable carbohydrates, and several host factors such as saliva. Saliva comprises several proteins which could be utilized as biomarkers for caries prevention, diagnosis, and prognosis. Mass spectrometry-based salivary proteomics approaches, owing to their sensitivity, provide the opportunity to investigate and unveil crucial cariogenic pathogen activity and host indicators and may demonstrate clinically relevant biomarkers to improve caries diagnosis and management. The present review outlines the published literature of human clinical proteomics investigations on caries and extensively elucidates frequently reported salivary proteins as biomarkers. This review also discusses important aspects while designing an experimental proteomics workflow. The protein-protein interactions and the clinical relevance of salivary proteins as biomarkers for caries, together with uninvestigated domains of the discipline are also discussed critically.

Saliva biomarkers in oral disease

Saliva is a versatile biofluid that contains a wide variety of biomarkers reflecting both physiologic and pathophysiologic states. Saliva collection is noninvasive and highly applicable for tests requiring serial sampling. Furthermore, advances in test accuracy, sensitivity and precision for saliva has improved diagnostic performance as well as the identification of novel markers especially in oral disease processes. These include dental caries, periodontitis, oral squamous cell carcinoma (OSCC) and Sjögren's syndrome (SS). Numerous growth factors, enzymes, interleukins and cytokines have been identified and are the subject of much research investigation. This review highlights current procedures for successful determination of saliva biomarkers including preanalytical factors associated with sampling, storage and pretreatment as well as subsequent analysis. Moreover, it provides an overview of the diagnostic applications of these salivary biomarkers in common oral diseases.

Salivary Enzymatic Activity and Carious Experience in Children: A Cross-Sectional Study

Salivary biomolecules are considered important modulators of the oral microflora, with a potential subsequent impact on dental health. The present study aimed to investigate the relationship between salivary enzymatic activity and carious experience in children. The carious experience of a sample of 22 school children was evaluated by calculating dmf/DMF indices, following WHO recommendations. Unstimulated whole saliva was collected, and salivary alpha-amylase levels, total protease activity, and matrix metalloproteinase levels (MMP-8 and MMP-9) were measured. The data were analyzed using parametric and nonparametric tests. Our findings revealed no significant relationship between the investigated salivary parameters and the carious experience in permanent teeth (DMFT/DMFS scores). Carious indices scores for primary teeth (dmft and dmfs) were positively associated with MMP-8 levels (r = 0.62, p = 0.004 and r_s = 0.61, p = 0.006, respectively) and MMP-9 levels (r = 0.45, p = 0.05 and r_s = 0.48, p = 0.039, respectively) and negatively associated with alpha-amylase levels (r_s = −0.54, p = 0.017 and r_s = −0.59, p = 0.006, respectively). Although with a marginal significance, PEK−054 levels positively correlated with dental caries, while for PFU−089, a negative correlation was observed. These results suggest that salivary alpha-amylase and MMP-8 and MMP-9 levels may be considered potential indicators of carious experience in children. Further studies with a prospective design are needed in order to elucidate the role of these biomolecules in caries development.

Reversal of Root Caries with Casein Phosphopeptide-Amorphous Calcium Phosphate and Fluoride Varnish in Xerostomia

Different formulas of topical fluoride have been used to manage root carious lesions. This clinical trial aimed to investigate the efficacy of a dental varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride compared with fluoride alone in reversing/arresting root caries in xerostomic patients over 1 year. A total of 80 patients (age range 45-92 years) with primary root caries (n = 184 root carious lesions) and unstimulated salivary flow rate of <0.2 mL/min were randomly allocated to receive either dental varnish containing CPP-ACP and 5% fluoride (group 1: MI varnish; GC, Japan) (n = 41, 83 lesions), or dental varnish with 5% fluoride alone (group 2: NUPRO White; Dentsply, USA) (n = 39, 101 lesions). Clinical assessments with Severity Index (SI) for root caries, DIAGNOdent measurements, and varnish application were carried out at baseline, 3, 6, and 12 months. Standard oral hygiene instructions with 1,450 ppm fluoride toothpastes were provided for both groups. After 3 months, 63.9% (n = 46) of root caries in group 1 became hard (SI: 0) compared with 39.3% (n = 35) in group 2 (p < 0.01). After 6 and 12 months, the differences in SI were insignificant (group 1, n = 60, 83.3%) (group 2, n = 66, 74.2%) (p = 0.36), and (group 1, n = 60, 89.6%) (group 2, n = 67, 81.7%, n = 1 soft, 1.2%) (p = 0.29), respectively. In both groups, noncavitated leathery lesions were more likely to become hard when compared to the cavitated root caries. A significant decrease in plaque index, surface roughness, lesion dimension, and DIAGNOdent readings with a significant increase in lesion distance from the gingival margin was reported in both groups (p < 0.05). This study has provided evidence that fluoride dental varnish either with or without calcium and phosphate has the potential to arrest/reverse root caries, especially noncavitated lesions for patients with xerostomia.

Comparison of decayed, missing, filled teeth index between thalassemia major patients and control group in Iran: a systematic review and meta-analysis

Introduction

Scientific evidence of the association between Decayed, Missing, and Filled Teeth (DMFT) and thalassemia are conflicting and difficult to establish conclusions. Therefore, this study aimed to determine the relationship between dental caries (using the DMFT index) and thalassemia major using meta-analysis.

Methods

Databases were searched using such keywords as “Thalassemia,” “Caries,” “decay,” “DMFT,” “Iran,” and OR operators, AND, and NOT. After the elimination of duplicate documentation, the articles which met the inclusion criteria were selected. Quality assessment was performed based on the Newcastle-Ottawa Quality Checklist. Thereafter, the standardized mean difference of the DMFT index was estimated.

Results

In eight studies, the mean DMFT was compared between patients with thalassemia major and the control group. In six studies, the mean of this index was higher in patients with thalassemia major than in the control group and in all six of the studies, the differences were statistically significant. The mean standardized difference of DMFT, D, M, and F were reported as 1.36 (0.41, 2.30), 2.63 (0.42, 4.84), 1.65 (−0.14, 3.45), and 0.02 (−1.67, 1.72), respectively.

Conclusion

The results of this meta-analysis indicated that DMFT index was more inappropriate in patients with thalassemia, as compared to the control group which represents the higher incidence of dental caries among patients with thalassemia compared to the control group.

Estimation of Proinflammatory Factors in the Saliva of Adult Patients with Cystic Fibrosis and Dental Caries

Introduction: The available literature lacks data regarding the levels of resistin, lysozyme, lactoferrin, α-amylase activity, pH, and saliva buffer capacity, as well as oral health and hygiene in the group of adult patients with cystic fibrosis (CF). The aim of the research was to assess the selected saliva parameters in patients diagnosed with cystic fibrosis. Materials and methods: Examined group was composed of 40 patients diagnosed with CF, while the control group of 40 healthy individuals. Both groups underwent the same scheme of the assessment (DMT index, salivary pH, buffer capacity, analysis of total sialic acid, total protein estimation, lysozyme levels estimation, lactofferin levels measurement, α-amylase activity, estimation of the levels of resistin and TNF-α). Results: In the examined group, there were higher values of decayed teeth as well as values of sialic acid, total protein, lactoferrin, α-amylase, and TNF-α. However, mean lysozyme, and resistin levels, as well as pH and buffer capacity of the saliva, were lower. Conclusions: New diagnostic methods, including the evaluation of selected salivary biochemical parameters, may indicate the existence of factors predisposing to severe tooth decay in the study group. Appropriate preventive treatment to combat dental caries in adult patients with CF will significantly improve their comfort and life expectancy.

Relationship of psychological factors with salivary flow rate and cortisol levels in individuals with oral lichen planus: A case-control study

OBJECTIVE

The objective of this study was to analyze the relationship between psychological factors and salivary flow rate and cortisol levels in individuals with oral lichen planus.

STUDY DESIGN

A case-control study of 21 individuals with clinical and histopathological diagnosis of oral lichen planus and 21 individuals without the disease (controls), matched by sex and age, was performed. The Beck Anxiety and Depression Inventories and Perceived Stress Scale were administered, and the salivary flow rate and salivary cortisol secretion pattern were determined. Data were statistically analyzed using Mann-Whitney U, McNemar's χ², and Student's t tests and the Spearman correlation coefficient. The significance level adopted was 5%.

RESULTS

Individuals with oral lichen planus had higher anxiety (P = .001), depression (P = .005), and perceived stress (P = .026) scores, but no association was found between the disease and salivary flow rate (P = .29) or with the pattern of salivary cortisol secretion (at awakening: P = .98; 30 min post-awakening: P = .95; at bedtime: P = .97).

CONCLUSION

An association was observed between oral lichen planus and anxiety, depression, and stress scores through psychological tests but not in relation to salivary flow rate and the pattern of salivary cortisol secretion.

Caries Status and Salivary Alterations of Type-1 Diabetes Mellitus in Children and Adolescents: A Systematic Review and Meta-analysis

INTRODUCTION

The association between dental caries, salivary alterations, and type-1 diabetes mellitus (D1TM) remains inconclusive in children and adolescents. This systematic review evaluated the caries status and salivary alterations of children and adolescents suffering from D1TM.

METHODS

Meta-analysis searched from 5 electronic databases was performed considering the decay-missing-filled teeth (DMFT), decay-missing-filled surfaces, and decay-missing-filled primary teeth (dmft) index for caries and the stimulated flow rate, unstimulated flow rate, and buffering capacity for salivary alterations. Quality assessments were performed using the Healthcare Research and Quality Agency.

RESULTS

Eleven studies satisfied the eligibility criteria. The meta-analysis revealed that DMF(T) (0.61; 95% confidence interval [CI], 0.14-1.08, P = .01) and dmft (-0.43; 95% CI, -0.71 to -0.15, P = .002) were significantly higher in D1TM group than the non-D1TM group. Stimulated flow rate (-0.40; 95% CI, -0.57 to -0.23, P < .00001) was significantly lower in D1TM group than in the non-D1TM group. No significant differences in decay-missing-filled surfaces and the buffering capacity were observed between the D1TM and the non-D1TM groups.

CONCLUSIONS

The level of DMF(T) and dmft was higher in children/adolescents with D1TM than that with non-D1TM, and the salivary flow could be considered decreased with D1TM. The strength of the evidence of the studies analyzed, however, was deemed to be moderate and low.

iTRAQ-based quantitative analysis of age-specific variations in salivary proteome of caries-susceptible individuals

Background

Human saliva is a protein-rich, easily accessible source of potential biomarkers for the diagnosis of oral and systemic diseases. However, little is known about the changes in salivary proteome associated with aging of patients with dental caries. Here, we applied isobaric tags for relative and absolute quantitation (iTRAQ) in combination with multiple reaction monitoring mass spectrometry (MRM-MS) to characterize the salivary proteome profiles of subjects of different ages, presenting with and without caries, with the aim of identifying age-related biomarkers for dental caries.

Methods

Unstimulated whole saliva samples were collected from 40 caries-free and caries-susceptible young adults and elderly individuals. Salivary proteins were extracted, reduced, alkylated, digested with trypsin and then analyzed using iTRAQ-coupled LC–MS/MS, followed by GO annotation, biological pathway analysis, hierarchical clustering analysis, and protein–protein interaction analysis. Candidate verification was then conducted using MRM-MS.

Results

Among 658 salivary proteins identified using tandem mass spectrometry, 435 proteins exhibited altered expression patterns in different age groups with and without caries. Of these proteins, 96 displayed age-specific changes among caries-susceptible adults and elderly individuals, and were mainly associated with salivary secretion pathway, while 110 age-specific proteins were identified among healthy individuals. It was found that the age factor caused significant variations and played an important role in both healthy and cariogenic salivary proteomes. Subsequently, a total of 136 target proteins with complex protein–protein interactions, including 14 age-specific proteins associated with caries, were further successfully validated using MRM analysis. Moreover, non-age-specific proteins (histatin-1 and BPI fold-containing family B member 1) were verified to be important candidate biomarkers for common dental caries.

Conclusions

Our proteomic analysis performed using the discovery-through-verification pipeline revealed distinct variations caused by age factor in both healthy and cariogenic salivary proteomes, highlighting the significance of age in the great potential of saliva for caries diagnosis and biomarker discovery.

Electronic supplementary material

The online version of this article (10.1186/s12967-018-1669-2) contains supplementary material, which is available to authorized users.

The effect of parotid gland-sparing intensity-modulated radiotherapy on salivary composition, flow rate and xerostomia measures

OBJECTIVES

To describe parotid gland (PG) saliva organic and inorganic composition and flow rate changes, after curative intensity-modulated radiotherapy (IMRT) for head and neck cancer (HNC), and analyse the relationship between PG saliva analytes and xerostomia measures.

METHODS AND MATERIALS

Twenty-six patients recruited to five prospective phase 2 or 3 trials which assessed toxicity and efficacy of IMRT by HNC subsite, provided longitudinal PG saliva. Salivary flow rate, and subjective and objective xerostomia measures were prospectively collected and saliva tested for inorganic and organic analytes. Statistical comparisons of longitudinal analyte changes and analysis for a relationship between dichotomized xerostomia score and saliva analytes were performed.

RESULTS

One hundred and forty-two PG saliva samples from 26 patients were analysed. At 3-6 months after IMRT, stimulated and unstimulated saliva showed significantly decreased flow rate, total protein (TP) secretion rate, phosphate concentration and increased lactoferrin (LF) concentration. Stimulated saliva alone had elevated LF secretion rate and beta-2-microglobulin (B₂ M) concentration with decreased calcium (Ca²⁺ ) and magnesium (Mg²⁺ ) concentrations and Ca²⁺ secretion rate. At >12 months, under stimulated and unstimulated conditions, increased LF concentration and decreased Mg²⁺ and phosphate concentration persisted and, in stimulated saliva, there was decreased potassium (K⁺ ) and Mg²⁺ concentration. Unstimulated TP secretion rate was lower in the presence of high-grade xerostomia. Otherwise, no relationship between xerostomia grade and PG salivary flow rate, TP and Ca²⁺ secretion rate was found.

CONCLUSION

Fewer significant differences in PG saliva analytes >12 months after IMRT indicate good functional recovery. Residual xerostomia after IMRT will only be further reduced by addressing the sparing of subsites of the PG or other salivary gland tissues, in addition to the PG.

Relationship among α amylase and carbonic anhydrase VI in saliva, visible biofilm, and early childhood caries: a longitudinal study

AIM

This longitudinal study investigated the relationship among early childhood caries (ECC), α amylase, carbonic anhydrase VI (CA VI), and the presence of visible biofilm, besides detecting if these variables could predict risk for ECC.

DESIGN

One hundred children were divided into two groups: caries group (n = 45) and caries-free group (n = 55). Visible biofilm on maxillary incisors was recorded, followed by caries diagnosis in preschoolers at baseline and at follow-up. Saliva samples were collected, and activities of CA VI and α amylase were determined. Data normality was assessed by Shapiro-Wilk test and then Mann-Whitney, Spearman correlation, and chi-square tests followed by multiple logistic regression analysis (α = 0.05, 95% confidence interval).

RESULTS

CA VI activity was significantly higher in saliva of children with caries (P ≤ 0.05), and α amylase activity was significantly higher in saliva of caries-free children (P < 0.0001). Children with α amylase activity in saliva lower than 122.8 U/mL (OR = 3.33 P = 0.042) and visible biofilm on maxillary incisors (OR = 3.6 P = 0.009) were more likely to develop ECC than caries-free children. A negative correlation between caries and α amylase activity was found (P = 0.0008).

CONCLUSIONS

The presence of visible biofilm and low salivary activity of α amylase may be considered risk predictors for ECC.

Oral health in prehistoric San Pedro de Atacama oases, Northern Chile

After almost 2000 years of local development, including limited trading with neighboring ethnic groups, the societies that occupied the oases of San Pedro de Atacama, Northern Chile, became part of the trade web of the Tiwanaku empire, between 500 and 1000 CE. Archaeological evidence tends to support the idea that the period under the influence of the altiplano (high plane) empire was very affluent. Here we investigate the possibility that this affluence had a positive impact on the health status of the Atacameneans, using the oral health as an indirect indicator of quality of life. Dental decay, dental abscess, dental wear, linear enamel hypoplasia, periodontal disease and dental calculus were analyzed on 371 skeletons from 12 sites from San Pedro de Atacama oases. We believe that if, indeed, there were better biological conditions during the altiplano influence, this could have been caused by the access to a more diversified food intake promoted by the intensification of the trading network established by Tiwanaku in the central-south Andes, of which San Pedro de Atacama became an important node.

Saliva composition in three selected groups with normal stimulated salivary flow rates, but yet major differences in caries experience and dental erosion

OBJECTIVE

It was hypothesized that, by comparing matched subjects with major differences in these dental diseases, but yet normal saliva flow rates, it would be possible to obtain data on the effect of saliva composition on dental disease isolated from the effect of the flow rate. Thus, the aim of the study was to compare the major physicochemical characteristics of stimulated whole saliva in three groups of 85 subjects, each with normal saliva flow rates and at least 24 remaining teeth.

MATERIALS AND METHODS

A group with very little dental disease (healthy), a group with dental erosion (erosion) and a group with very high caries experience (caries) were chosen. Furthermore, the aim was to determine whether differences among groups could also be found on an individual level.

RESULTS

Although it was not possible to retrieve three groups whose members were completely identical, the present study points in the direction that, on a group level, subjects with very little dental disease seemed to have a more favorable physicochemical saliva composition with respect to higher calcium, phosphate, bicarbonate, pH, degree of saturation with respect to hydroxyapatite and a lower critical pH (p < 0.05 or less). However, on an individual level the explanatory power for the saliva composition was only 10% for caries experience and only 11% for dental erosion (p < 0.001).

CONCLUSION

The compositional analyses performed in this study on stimulated whole saliva, including major physicochemical characteristics of saliva, will most likely have little predictive value for future dental caries and erosion in single individuals.

The proteome of the human parotid gland secretion in elderly with and without root caries

OBJECTIVE

Saliva is important for oral health, including the prevention of dental decay. The purpose of the present work was to indicate whether the parotid gland has altered function in the elderly, particularly in terms of proteins secreted, and whether its functional status could be associated with the presence of root caries.

MATERIAL AND METHODS

Ductal parotid gland secretion was obtained from 51 individuals: 21 elderly with carious roots (Patients), 20 elderly (Controls), and 10 adults (Young) without root caries. Pooled aliquots were analyzed by liquid chromatography/tandem mass spectrometry to yield lists of major proteins present in the three groups.

RESULTS

Approximately 200 unique proteins were detected, of which 73 were identified repeatedly with high confidence and therefore included in the comparison. Some of the differences observed, when comparing Patients with respectively elderly Controls and the Young, resembled changes found in patients with Sjogren's syndrome, a condition associated with dental decay. Other changes involved proteins that are likely to impact on the oral microbiota, such as the absence of dermcidin and the presence of collagen in Patients. Cystatin S, a putative indicator of caries, was present at a higher level in Patients.

CONCLUSIONS

Parotid function tends to change upon aging, with possible consequences as to caries activity. However, analyses of individual samples revealed considerable variations in protein patterns.

Interaction of age and specific saliva component output on caries

BACKGROUND AND AIMS

The purpose of this study was to explore the relationship between individual salivary components, dental caries and age, utilizing the data from the Oral Health: San Antonio Longitudinal Study of Aging (OH:SALSA).

METHODS

The study population comprised a well-defined stratified sample of 811 dentate men and women. Subjects were divided into four age groups from 35 to 75+ years old. Unstimulated and stimulated submandibular/sublingual saliva flow rates, unstimulated and stimulated parotid saliva flow rates, total protein, 6 individual proteins and 4 inorganic constituents were measured. Specific salivary components were lactoferrin, secretory IgA, albumin, lysozyme, mucin, cystatin, K+, Ca2+, Na+ and Cl-. Caries measurements were the DMFT Index for crowns and for roots, Tooth Health Index for crowns and roots, Tooth caries, Root caries and Tooth restoration. The data on saliva components were square root transformed for linearity prior to analysis. Analysis was carried out in two stages. Partial correlation was performed, in order to identify significant relationships between specific salivary components and caries measurements, controlling for age group. In the second stage, using caries measurement as the dependant variable, the effects of age, flow rate and specific salivary component output (product of flow rate and concentration) were examined.

RESULTS

Significant associations were found between caries, age and specific individual submandibular/sublingual salivary proteins (lactoferrin, albumin, lysozyme, mucin and cystatin) and specific inorganic constituents (K+, Ca2+, Na+ and Cl-).

CONCLUSIONS

Changes in submandibular/ sublingual salivary component output during aging are correlated with high caries prevalence. These changes in saliva components over age may represent caries risk indicators.

Analysis of the human saliva proteome

Interest in the characterization of the salivary proteome has increased in the last few years. This review discusses the different techniques and methodologies applied to the separation and identification of salivary proteins. Nowadays, proteomic techniques are the state of the art for the analysis of biologic materials and saliva is no exception. 2D electrophoresis and tryptic digest analysis by mass spectrometry are the typical methodology, but new approaches using 2D liquid chromatography/mass spectrometry methods have already been introduced for saliva analysis. Due to their important physiologic role in the oral cavity, low-molecular-weight proteins and peptides are also included in this article and the methodologies discussed.

Oral health measurement in nursing research: state of the science

Oral health can impact general health and systemic disease. Changes in dental plaque, oral microbial flora, and local oral immunity may be important in the development or exacerbation of disease in critically ill patients, trauma patients, adults with chronic obstructive pulmonary disease, and frail elderly. Inasmuch as oral health potentially can be influenced by nursing interventions, nursing research in this area can contribute greatly to improved patient outcomes in these diverse populations. The authors' research teams have conducted several federally funded projects focused on oral health and have developed synergy in research methods. A unifying theme for these research projects is the measurement of oral health. Standardized measures of components of oral health are available and applicable across populations, and their uses and relationship to nursing research and patient outcomes will be discussed.

Dental caries and salivary status in children with type 1 diabetes mellitus, related to the metabolic control of the disease

The aim of this study was to investigate the relationship among type 1 diabetes mellitus, dental caries, and salivary status in children. The study comprised 68, 10-15-yr-old diabetics, and 68, age- and gender-matched non-diabetic controls. Diabetics were categorized into well-to-moderately controlled (HbA1c < 9.0%) and poorly controlled (HbA1c >or= 9.0%) groups. Caries was recorded by assessing lesion activity at non-cavitated and cavity levels. Teeth were examined visually for the presence of dental plaque. Saliva was analyzed for unstimulated and stimulated flow rates, buffer effect, mutans streptococci, lactobacilli, and yeasts. Diabetics had fewer caries and plaque, lower salivary flow rates and buffer effect, and more frequent growth of yeasts than their non-diabetic controls. Well-to-moderately controlled diabetics had fewer decayed surfaces and lower counts of mutans streptococci and yeasts than poorly controlled diabetics, but the level of metabolic control of diabetes had no influence on salivary flow rates and buffer effect. High caries levels in diabetics were significantly associated with age, plaque score, and decreased unstimulated salivary flow rate, but were not associated with the level of metabolic control of diabetes. High caries experience in this study population could be related to plaque accumulation and/or to changes in saliva induced by diabetes mellitus.