Electrophoretic analysis of whole saliva and prevalence of dental caries. A study in Mexican dental students

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.

Salivary Diagnosis of Dental Caries: A Systematic Review

The activity of dental caries, combined with its multifactorial etiology, alters salivary molecule composition. The present systematic review was developed to answer the following question: "Are salivary biomarkers reliable for diagnosis of dental caries?". Following the "Preferred Reporting Item for Systematic Reviews and Meta-analysis" (PRISMA) guidelines, the review was conducted using multiple database research (Medline, Web of Science, and Scopus). Studies performed on healthy subjects with and without dental caries and providing detailed information concerning the clinical diagnosis of caries (Decayed, Missing, Filled Teeth-DMFT and International Caries Detection and Assessment System-ICDAS criteria) were included. The quality assessment was performed following a modified version of the Joanna Briggs Institute Prevalence Critical Appraisal Checklist. The protocol was registered in the International Prospective Register of Systematic Reviews (PROSPERO, ID: CRD42022304505). Sixteen papers were included in the review. All studies reported statistically significant differences in the concentration of salivary molecules between subjects with and without caries (p < 0.05). Proteins were the most investigated molecules, in particular alpha-amylase and mucins. Some studies present a risk of bias, such as identifying confounding factors and clearly defining the source population. Nevertheless, the 16 papers were judged to be of moderate to high quality. There is evidence that some salivary compounds studied in this review could play an important diagnostic role for dental caries, such as salivary mucins, glycoproteins (sCD14), interleukins (IL-2RA, 4,-13), urease, carbonic anhydrase VI, and urea.

Estimation and Association of Total Protein Concentration with Early Childhood Caries in 3-6-year-old Children: A Randomized Clinical Trial

Background and objective

Caries is a common problem witnessed in children, early childhood caries (ECC) is the most predominant chronic disease which not only leads to distress and pain but also poor quality of life, thus affecting the overall well-being of children. Salivary protein plays a vital part in monitoring health status or disease. It was stated that the salivary proteins could regulate the equilibrium of oral health, preserve a stable ecosystem, and constrain the growth of cariogenic bacteria.

Aim

The aim of this study is to estimate the total protein concentration in saliva and its correlation to ECC.

Materials and methods

A total of 20 patients with ECC in the age-group of 3-6 years were selected as the experimental group and 20 patients without caries for the control group. Unstimulated saliva samples were collected and subjected to spectrophotometry. The data obtained was subjected to statistical analysis. Independent student's t-test was used for the comparison of mean salivary pH between the caries group and the control group. Mann-Whitney test was used for a comparison of salivary total protein concentrations between the two groups.

Results

The mean pH of the carious group showed a statistically significant slightly lower value than that of the noncarious group. On the contrary, the mean total protein concentration of the carious group presented a statistically significant higher value than that of the noncarious group. Age-wise comparison of mean salivary proteins in the carious group and the noncarious group showed an increase in the protein concentration in the children aged 4 years or younger.

Conclusion

Based on the results of this study, it can be concluded that there is a strong association between the total protein concentration in saliva and ECC. There exists a significant increase in the total protein concentration in children with ECC. As age increases, total protein concentration decreases with age.

Clinical significance

Total protein concentration and particular protein estimation and quantification help us in assessing the risk of caries in children at the earliest and prevention of caries through preventive measures. Estimation of total salivary protein concentration in children can be a marker for ECC in children.

How to cite this article

Thimmegowda U, Pai S, Chikkanarasaiah N, et al. Estimation and Association of Total Protein Concentration with Early Childhood Caries in 3-6-year-old Children: A Randomized Clinical Trial. Int J Clin Pediatr Dent 2024;17(1):36-40.

Differentially Expressed Salivary Proteins in Dental Caries Patients

Dental caries is a multifactorial disease mainly caused by cariogenic bacteria commonly found in the oral cavity. Dental caries may cause demineralization of the tooth, cavitation, hypersensitivity, pulp inflammation, and even tooth loss if left untreated. Saliva secreted in the oral cavity can serve as a tool for identification of biomarkers for early detection of diseases. In the present study, differential expression of salivary proteins from 33 dental caries patients was compared with 10 control subjects. The unstimulated saliva was analyzed by 12% SDS-PAGE and two-dimensional gel electrophoresis. Gelatin and casein zymography was performed to check for protease activity. Also, salivary IgAs from both groups were compared by sandwich ELISA technique. Dental caries patient's saliva showed decreased caseinolytic and increased gelatinolytic activity probably due to metalloproteases and cathepsins. Mean salivary levels of sIgA were also significantly higher (p < 0.018) in dental caries saliva samples. The 2D electrophoresis profile of both the groups showed regions on gel with visually detectable alterations in protein expression. The present study is among the few initial studies in the locality for identification of protein differences in saliva from dental caries patients and has demonstrated a good potential to identify alterations. However, a large population-based analysis is required to validate these findings to be translated as a tool for indicative applications.

Estimation of salivary proteins in early childhood caries before and after treatment using gel electrophoresis

BACKGROUND

Saliva being an important biological fluid of our body contains both specific and nonspecific protective factors which form an integral part of our immune system. Salivary proteins play a substantial role in protecting humans against infection. Their level in oral cavity is subject to constant variations which is dependent on various factors.

PURPOSE

The purpose of the study was to compare the levels of salivary proline-rich proteins (PRPs), glycoproteins, amylase bands, and salivary pH in children with early childhood caries before and after treatment using gel electrophoresis.

MATERIALS AND METHODS

The whole salivary pH, mean protein concentrations, and electrophoretic profiles of the salivary proteins were measured using sodium dodecylsulfate-polyacrylamide gel electrophoresis in both pre- and posttreatment groups. Statistical analysis was done using Statistical Package for Social Sciences (SPSS) version 15.0 software. Chi-square test and independent t-test were used to further compare the results.

RESULTS

The results were statistically significant in all the groups. There was variation in pre- and posttreatment values seen.

CONCLUSION

Salivary proteins (glycoproteins, PRPs, and amylase) establish an imperative defense mechanism as antimicrobial agents.

The role of sugar-rich diet and salivary proteins in dental plaque formation and oral health

BACKGROUND

Dental plaque is a complex colorless film of bacteria that develops on the surfaces of teeth. Different mechanisms of microbial adhesion to tooth surfaces exist. Both non-specific and specific types of adherence have been anticipated.

HIGHLIGHT

The present review evaluated the effect of sugar-rich diet and salivary proteins on oral hygiene and dental plaque development.

CONCLUSION

The oral microbiota is essential for maintaining and reestablishing a healthy oral cavity. Different types of sugars have different effects on the inhibition and formation of dental plaque. The peptides, proteins, and amino acids secreted by parotid glands in the oral cavity facilitate neutralizing the acidity in dental plaque and preventing dental caries. A properly balanced diet is crucial for both a healthy oral cavity and the oral microbiome.

Dental caries: Genetic and protein interactions

OBJECTIVE

To present a genetic and protein interaction analysis associated with dental caries.

MATERIAL AND METHODS

The first step was to conduct a systematic literature review (SLR) through an electronic database search. Case-controls that reported associations between genes and dental caries were the main type of study design used as inclusion criteria, retrieved from the PubMed and the Virtual Health Library databases, comprising the chronological range from 1982 to 2017. The SLR was guided by PRISMA protocol and the methodological quality of the studies was established through Newcastle-Ottawa Scale (NOS). In the second step, the String Protein Interaction (SPI) approach was used to analyze protein interaction (by esyN software) and also the Ingenuity Pathway Analysis (IPA) to check biological pathways associated with dental caries genes.

RESULTS

A total of 51 articles were included to perform this SLR, describing a number of 27 genes associated with dental caries development. At the genetic level, 23 genes have at least one other gene with which they interact. The genes TUFT1, VDR, TFIP11, LTF, HLA-DRB1, MMP2, MMP3 and MUC5B were shown to be connected in interactive networks by at least 10 other genes.

CONCLUSION

It is essential to apprehend the multifactorial pattern of inheritance in human disease. This study presents pathways which may be directly correlated with several dental caries phenotype and this contributes to a better understanding of this disease, opening up a wider range of biotechnology options for its effective control in the future.

MUC7 Level As A New Saliva Risk Factor For Dental Caries In Adult Patients

Purpose: Data currently available indicate the significance of salivary mucins MUC5B and MUC7 in the protection of teeth against caries. Our study aimed to determine the relationship between dental caries in adults and levels of MUC5B and MUC7. Methods: The studies were conducted on 45 adult subjects selected on the basis of dental examination and calculation of the DMFT (Decayed, Missing, and Filled Teeth) index. Among these patients, two research groups were distinguished: group 1 included 19 caries-free subjects (DMFT = 0); and group 2 included 26 patients with severe caries (DMFT > 13.9). Samples of whole unstimulated saliva were collected and centrifuged. MUC5B and MUC7 content in saliva supernatant were estimated using an enzyme-linked immunosorbent sandwich assay (ELISA). Analysis of the obtained data receiver operating characteristic (ROC) curves was employed to define relationships between the contents of the studied mucins and the detected dental caries. Results: In subjects from group 1, the mean level of MUC5B amounted to 0.63 ± 0.35 ng/ml and this was significantly higher than the concentration of mucin in patients of group 2, which amounted to 0.38 ± 0.32 ng/ml (p = 0.023). The mean level of MUC7 amounted to 5.47 ± 1.18 ng/ml and this was significantly higher than the level of the mucin in group 2, which was 1.39 ± 0.86 ng/ml (p< 0.0001). In parallel, a relationship was detected between levels of the examined mucins and manifestation of dental caries. For MUC7, the optimal cut-off value was obtained (i.e. corresponding to 100% sensitivity and specificity), amounting to 2.5 ng/ml for the detection of dental caries risk. Conclusions: Development of dental caries is linked to reduced concentrations of MUC5B and MUC7. The level of MUC7 may represent a significant parameter clinically suitable for evaluation of disease risk.

Human salivary proteins and their peptidomimetics: Values of function, early diagnosis, and therapeutic potential in combating dental caries

Saliva contains a large number of proteins that play various crucial roles to maintain the oral health and tooth integrity. This oral fluid is proposed to be one of the most important host factors, serving as a special medium for monitoring aspects of microorganisms, diet and host susceptibility involved in the caries process. Extensive salivary proteomic and peptidomic studies have resulted in considerable advances in the field of biomarkers discovery for dental caries. These salivary biomarkers may be exploited for the prediction, diagnosis, prognosis and treatment of dental caries, many of which could also provide the potential templates for bioactive peptides used for the biomimetic management of dental caries, rather than repairing caries lesions with artificial materials. A comprehensive understanding of the biological function of salivary proteins as well as their derived biomimetic peptides with promising potential against dental caries has been long awaited. This review overviewed a collection of current literature and addressed the majority of different functions of salivary proteins and peptides with their potential as functional biomarkers for caries risk assessment and clinical prospects for the anti-caries application.

The Predictive Potentiality of Salivary Microbiome for the Recurrence of Early Childhood Caries

The aim of this study was to investigate the variation of the salivary microbiota in the recurrence of early childhood caries (ECC), and to explore and verify the potential microbial indicators of ECC recurrence. Saliva samples from kindergarten children were tracked every 6 months for 1 year. Finally, in total 28 children and 84 samples were placed on the analysis phase: 7 children with ECC recurrence made up the ECC-recurrence (ER) group, 6 children without ECC recurrence constituted the non-ECC-recurrence (NER) group, and 15 children who kept ECC-free were set as the ECC-free (EF) group. DNA amplicons of the V3-V4 hypervariable region of the bacterial 16S rDNA were generated and sequencing was performed using Illumina MiSeq PE250 platform. No statistically significant differences of the Shannon indices were found in both cross-sectional and longitudinal comparisons. Furthermore, both principal coordinates analysis (PCoA) and heatmap plots demonstrated that the salivary microbial community structure might have potentiality to predict ECC recurrence at an early phase. The relative abundance of Fusobacterium, Prevotella, Leptotrichia, and Capnocytophaga differed significantly between the ER and NER groups at baseline. The values of area under the curve (AUC) of the four genera and their combined synthesis in the prediction for ECC recurrence were 0.857, 0.833, 0.786, 0.833, and 0.952, respectively. The relative abundance of Fusobacterium, Prevotella, Leptotrichia, and Capnocytophaga and their combination showed satisfactory accuracy in the prediction for ECC recurrence, indicating that salivary microbiome had predictive potentiality for recurrence of this disease. These findings might facilitate more effective strategy to be taken in the management of the recurrence of ECC.

Salivary Protein Roles in Oral Health and as Predictors of Caries Risk

This work describes the current state of research on the potential relationship between protein content in human saliva and dental caries, which remains among the most common oral diseases and causes irreversible damage in the oral cavity. An understanding the whole saliva proteome in the oral cavity could serve as a prerequisite to obtaining insight into the etiology of tooth decay at early stages. To date, however, there is no comprehensive evidence showing that salivary proteins could serve as potential indicators for the early diagnosis of the risk factors causing dental caries. Therefore, proteomics indicates the promising direction of future investigations of such factors, including diagnosis and thus prevention in dental therapy.

Salivary proteins and microbiota as biomarkers for early childhood caries risk assessment

Early childhood caries (ECC) is a term used to describe dental caries in children aged 6 years or younger. Oral streptococci, such as Streptococcus mutans and Streptococcus sorbrinus, are considered to be the main etiological agents of tooth decay in children. Other bacteria, such as Prevotella spp. and Lactobacillus spp., and fungus, that is, Candida albicans, are related to the development and progression of ECC. Biomolecules in saliva, mainly proteins, affect the survival of oral microorganisms by multiple innate defensive mechanisms, thus modulating the oral microflora. Therefore, the protein composition of saliva can be a sensitive indicator for dental health. Resistance or susceptibility to caries may be significantly correlated with alterations in salivary protein components. Some oral microorganisms and saliva proteins may serve as useful biomarkers in predicting the risk and prognosis of caries. Current research has generated abundant information that contributes to a better understanding of the roles of microorganisms and salivary proteins in ECC occurrence and prevention. This review summarizes the microorganisms that cause caries and tooth-protective salivary proteins with their potential as functional biomarkers for ECC risk assessment. The identification of biomarkers for children at high risk of ECC is not only critical for early diagnosis but also important for preventing and treating the disease.

Analysis of Salivary IgA, Amylase, Lactoferrin, and Lysozyme Before and After Comprehensive Dental Treatment in Children: A Prospective Study

Objective:

This study aimed to evaluate the levels of salivary IgA, amylase, lactoferrin, and lysozyme before and after comprehensive dental treatment in children with early childhood caries.

Design:

Thirty children aged 36–60 months, with a deft score ≥5, were selected for the study. Before dental treatment, paraffin-stimulated whole saliva was collected in a sterile graduated cup for a period of 5 min. The saliva samples were quantitatively analyzed for levels of IgA, amylase, lactoferrin, and lysozyme using enzyme-linked immunosorbent assay. Comprehensive dental treatment was carried out in all the children including caries preventive procedures. A second sample of saliva was collected at 3 months following completion of dental treatment. Data obtained was subjected to statistical analysis using Student's t-test.

Results:

The mean levels of salivary IgA was significantly reduced from 59.60 μg/ml to 56.42 μg/ml after dental treatment (P < 0.05). There was a significant reduction in the levels of salivary amylase from 115.78 μg/ml to 113.33 μg/ml (P < 0.001). Following dental treatment, salivary lactoferrin and lysozyme levels were significantly reduced from 3.76 μg/ml and 10.62 μg/ml to 3.44 μg/ml and 10.27 μg/ml, respectively (P < 0.001).

Conclusions:

Levels of salivary IgA, amylase, lactoferrin, and lysozyme were reduced significantly at 3 months following comprehensive dental treatment.

Obstructive sleep apnoea syndrome does not negatively affect oral and dental health

Objective:

Obstructive sleep apnoea syndrome can lead to unhealthy open-mouth breathing. We investigated the possible relationship between obstructive sleep apnoea syndrome and dental health. We also evaluated other clinical factors that may affect oral health.

Methods:

We measured sleep using polysomnography and determined the apnoea–hypopnoea index for a total of 291 patients. We also recorded the demographic data, duration of snoring complaints, educational status and income levels for our patient cohort; finally, we calculated the decayed, missing and filled teeth index.

Results:

Forty-one patients presented with primary snoring (control group) and 250 patients (study group) presented with mild, moderate and severe obstructive sleep apnoea syndrome. We found no correlation between obstructive sleep apnoea syndrome severity and the decayed, missing and filled teeth index (p = 0.057). We also found no correlation between the apnoea–hypopnoea and decayed, missing and filled teeth indexes. Age and the duration of snoring complaints were positively correlated with the decayed, missing and filled teeth index while educational status and income levels were negatively correlated (p < 0.001).

Conclusion:

Obstructive sleep apnoea syndrome does not negatively affect oral and dental health.

Salivary mucin 19 glycoproteins: innate immune functions in Streptococcus mutans-induced caries in mice and evidence for expression in human saliva

Saliva functions in innate immunity of the oral cavity, protecting against demineralization of teeth (i.e. dental caries), a highly prevalent infectious disease associated with Streptococcus mutans, a pathogen also linked to endocarditis and atheromatous plaques. Gel-forming mucins are a major constituent of saliva. Because Muc19 is the dominant salivary gel-forming mucin in mice, we studied Muc19(-/-) mice for changes in innate immune functions of saliva in interactions with S. mutans. When challenged with S. mutans and a cariogenic diet, total smooth and sulcal surface lesions are more than 2- and 1.6-fold higher in Muc19(-/-) mice compared with wild type, whereas the severity of lesions are up to 6- and 10-fold higher, respectively. Furthermore, the oral microbiota of Muc19(-/-) mice display higher levels of indigenous streptococci. Results emphasize the importance of a single salivary constituent in the innate immune functions of saliva. In vitro studies of S. mutans and Muc19 interactions (i.e. adherence, aggregation, and biofilm formation) demonstrate Muc19 poorly aggregates S. mutans. Nonetheless, aggregation is enhanced upon adding Muc19 to saliva from Muc19(-/-) mice, indicating Muc19 assists in bacterial clearance through formation of heterotypic complexes with salivary constituents that bind S. mutans, thus representing a novel innate immune function for salivary gel-forming mucins. In humans, expression of salivary MUC19 is unclear. We find MUC19 transcripts in salivary glands of seven subjects and demonstrate MUC19 glycoproteins in glandular mucous cells and saliva. Similarities and differences between mice and humans in the expression and functions of salivary gel-forming mucins are discussed.

The effect of social stress on salivary trace elements

Social stress can alter the saliva in favor of metabolism of trace elements. This study aimed to assess the effect of social stress on salivary copper (Cu), zinc (Zn), manganese (Mn), and iron (Fe) contents in dental students before and after a comprehensive English test. Twelve students with an average age of 27 years were selected from three dental schools. The students were carries-free, and salivary samples were collected 1 week before the test day and right before the comprehensive English test. Unstimulated saliva was collected from the participants. The pH of the saliva samples was measured using a portable pH meter, and the salivary trace element contents were determined using an atomic absorption spectrophotometer. After checking data to be normally distributed, Student's paired t test was used for statistical analysis. Salivary pH significantly increased right before the English test. Salivary Cu concentration decreased in students after the test (P > 0.05). The level of Zn, Mn, and Fe increased, while only Mn change was statistically significant (P < 0.001). Under the limitations of this study, induction of social stress led to a significant increase in Mn concentration in the saliva. The salivary Cu, Zn, and Fe contents, however, did not exhibit significant changes. Changes in salivary inorganic trace element content, as a result of physiological stress, might influence health of teeth, enamel, and oral mucosal tissues.

Total antioxidant capacity of saliva and dental caries

OBJECTIVE

Dental caries is one of the most common infectious diseases worldwide. Saliva has many functions in the oral cavity and is the first line defense against dental caries. Oxidative stress can affect initiation and progression of many inflammatory and infectious diseases such as dental caries. Thus the aim of this study was to evaluate the relationship between total antioxidant capacity (TAC) of saliva and dental caries.

STUDY DESIGN

100 healthy high school students (50 female and 50 male) with age range of 15 -17 years were randomly selected, divided to four groups. Unstimulated whole saliva specimens were collected at the morning. TAC of saliva was evaluated by spectrophotometric assay. Statistical comparisons were performed using Student's t-test, by SPSS 13.

RESULTS

The level of TAC was significantly higher in the saliva of caries active group relative to the caries free subjects. Statistical analysis for male and female groups showed a statistically significant reduction of TAC level in female group.

CONCLUSION

TAC was higher in caries active group. Thus this result showed that total antioxidant capacity may influence in dental caries and activity can be measured by salivary factors and this may be helpful in preventive dentistry.

Salivary proteins as a biomarker for dental caries--a systematic review

AIM

To develop a systematic review based on the relation between salivary proteins and dental caries by comparing subjects with and without caries experience and to evaluate whether salivary proteins can be considered biomarkers for dental caries or not.

METHODS

An electronic search was performed in the PubMed Medline, Ovid Medline, ISI Web of Science, Medline, Cochrane Library, Lilacs, Scielo, BBO, Paho and Wholis databases applying the following MeSH terms: "dental caries" OR "tooth demineralization" OR "dental caries susceptibility" OR "dental enamel solubility" AND "salivary proteins and peptides" OR "saliva" AND "proteins". To be eligible for the systematic review, the observational controlled studies had to have groups with and without caries experience. Studies with high risk of bias were excluded.

RESULTS

From a total of 188 identified studies, only seven were included in this systematic review. Four studies were classified as "low risk of bias" and three as "moderate risk of bias". Three studies reported a relation between salivary proteins and dental caries.

CONCLUSION

There was not sufficient evidence to establish salivary proteins as a biomarker for this disease although three of the seven studies showed a relation between salivary proteins and dental caries in terms of protein phenotypes, total protein concentration and protein molecular weight.

Identification of salivary proteins at oil-water interfaces stabilized by lysozyme and beta-lactoglobulin

In this research, we investigated the interaction occurring between oil-in-water emulsion droplets, stabilized by different emulsifiers, i.e. lysozyme and beta-lactoglobulin (beta-lg), and salivary proteins (SPs) with a molecular mass (M(r)) above about 10kDa. Different techniques, i.e. infrared spectroscopy, Western blotting, PAS staining and SDS-PAGE coupled to MS, were employed for this purpose. This study demonstrated the interaction between several salivary proteins and the emulsifiers at the oil-water interfaces. In particular, results show that the high M(r) mucin MUC5B was strongly bound to lysozyme stabilized emulsions, whereas beta-lg stabilized emulsions associated with MUC7 and, moderately, with MUC5B. Furthermore, we observed that salivary proteins in the range M(r) 10-100kDa associated differently with emulsion droplets. A large majority of SPs was found to interact with lysozyme stabilized emulsion droplets whilst in case of beta-lg stabilized emulsions, the SPs distribute more evenly between the fraction associated and non-associated with the droplets. A clear example is alpha-amylase (M(r) approximately 55kDa) which predominantly associates with lysozyme stabilized emulsion droplets, but not with beta-lg emulsion droplets. To conclude, our findings indicate that adsorption/association of salivary protein components onto the emulsion droplets is related to the type of emulsifying proteins at the oil-water interfaces and it is probably driven by the overall net charge at the droplet's oil-water interfaces, i.e. positive for lysozyme stabilized emulsions and negative for beta-lactoglobulin stabilized emulsion at neutral pH.

Salivary proteins and early childhood caries: A gel electrophoretic analysis

BACKGROUND

Early childhood caries (ECC) is a common disease process that afflicts a large proportion of the child population worldwide. Extensive research in past indicates that it is the result of bacterial infection, also influenced by host and dietary factors. Current caries research seeks to identify risk factors as well as natural oral defenses that may protect against or prevent caries development. Saliva, in spite of being the strongest defense system, still has a wide array of properties and proteins whose role is yet not clearly known.

AIM

To compare the resting human whole salivary characteristics in children with ECC and those who are caries free.

SETTINGS AND DESIGN

The study was conducted over a period of 9 months in 4- to 6-year-old 100 children comprising two groups - 50 with ECC and 50 caries free.

MATERIALS AND METHODS

The whole salivary flow rate, pH, mean protein concentration, and the electrophoretic profile of salivary proteins by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) were compared among both groups.

STATISTICAL ANALYSIS

The SPSS (version 11.0) software package was used to conduct the chi-square, Fisher's exact and Pearson's chi-square tests to compare the data.

RESULTS

On gel electrophoresis, there was a significant difference among both groups with caries-free subjects having a higher number of proline-rich protein bands, substantiating the protective role of this protein. A significantly higher number of glycoprotein bands were observed in the whole saliva of subjects with ECC. A significant inverse correlation between the mean protein concentration and the whole salivary flow rate was observed in both groups.

Interaction of copper and human salivary proteins

Interaction of taste molecules with saliva is the first step in the flavor perception process. Saliva is assumed to influence copper-induced sensation by controlling the copper solubility or causing astringency via binding of proteins with copper. This study was performed to identify the nature of copper-protein interactions in relation to the sensory perception of copper. Saliva was treated with CuSO4 x 5H2O at levels of 0, 2.5, 5, 10, 20, or 40 mg/L, and changes in salivary proteins were analyzed using high performance liquid chromatography (HPLC) and sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). Protein peaks that showed changes in HPLC were characterized with SDS-PAGE. HPLC analysis revealed that copper treatment up to 40 mg/L decreased several proteins, including the dominant peak, by 70%. This peak was composed of alpha-amylase, a secretory component, and basic proline-rich proteins. SDS-PAGE results showed that salivary proteins of molecular weight 29 kDa and 33 kDa precipitated when copper was added at concentrations > or =10 mg/L. This study provides biochemical information for understanding perception mechanisms of copper sensation.

Absence of soluble CD14 in saliva of young patients with dental caries

It is generally accepted that salivary components are important for dental health, but to date no clear correlation has been found between one or more of these components and the outcome of dental caries. The identification of salivary factors preventing, favoring or signaling dental caries might help to control the disease. In the present study, western blotting analysis of whole saliva from 20 healthy caries-free children showed the presence of the soluble form of CD14, a bacterial pattern-recognition receptor for many bacterial components that is involved in the innate immune response. The identity of the protein was confirmed through N-terminal sequencing by Edman degradation, and by partial sequencing with mass spectrometry of tryptic peptides. Conversely, CD14 was completely absent in the saliva of 20 age-matched patients affected by two to eight carious lesions, but appeared in their saliva a few weeks after dental restoration. These results suggest that the absence of salivary soluble CD14 could represent an useful index of caries activity, and might be used to detect early carious lesions not visible by oral inspection.

Relationship between total salivary protein content and volatile sulfur compounds levels in malodor patients

OBJECTIVE

The purpose of this study was to evaluate the relationship between total salivary protein and VSC levels.

STUDY DESIGN

A patient group comprised 67 patients from the Fresh Breath Clinic of the Dental Hospital, Tokyo Medical and Dental University, with 18 healthy subjects as a control group. Gas chromatography was used to measure concentrations of VSCs in mouth air. After collecting resting saliva, flow rate, pH, and the amount of total protein in saliva were measured. Salivary protein patterns were analyzed by polyacrylamide gel electrophoresis (PAGE).

RESULTS

In the patient group, the amounts of total salivary protein were significantly correlated with CH3SH levels measured by GC, CH3SH/H2S ratio, and organoleptic score. In addition, a significant correlation between flow rate of salivary protein and CH3SH/H2S ratio and the higher levels of salivary proteins from PAGE analyses were found.

CONCLUSIONS

Total salivary protein was considered to be involved in the formation of oral malodor as one of the nutrient sources. The total salivary protein could be changed both quantitatively and qualitatively in subjects with malodor.

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.

Two-dimensional electrophoresis study of in vitro pellicle formation and dental caries susceptibility

In the present study, a proteomic approach was applied to evaluate the influence of salivary protein composition on in vitro dental pellicle formation and its possible correlation with dental caries. Whole saliva, collected from caries-free and caries-susceptible subjects, was analyzed by two-dimensional electrophoresis, and protein spots were identified by mass spectrometry. Data analysis of salivary protein composition showed a statistically significant correlation between the quantity of acidic proline-rich proteins (PRPs), lipocalin, cystatin SN and cystatin S, and samples from the caries-free group of subjects [decayed, missing or filled teeth (DMFT) = 0]. Samples from subjects with a high DMFT index appear to be correlated with high levels of amylase, immunoglobulin A, and lactoferrin. In vitro pellicle-composition experiments showed the same correlations found for whole saliva. As cystatins are known physiological inhibitors of cathepsins, the higher quantities of lipocalin, and cystatins S and SN found in the samples from the caries-free subjects suggest that inhibition of proteolytic events on other salivary proteins may indirectly provide tooth protection. The correlation between higher levels of the phosphorylated acidic PRPs 1/2 with samples from the caries-free group also suggests a protective role for these proteins.

Microradiographic study on the effects of salivary proteins on in vitro demineralization of bovine enamel

The aim of this investigation was to evaluate the effects of various proteins on in vitro demineralization of bovine enamel. From each of 100 bovine incisors two samples were prepared. The specimens were embedded in epoxy resin and polished up to 4000 grit. Subsequently, the specimens' surfaces were partly covered with nail varnish, thus serving as control of sound enamel. The specimens were divided randomly into five groups (n = 40) and demineralized in a solution of constant composition (pH 5.0; 10 days). For each subgroup of specimens (n = 10) 4 L were taken and either low (50% of medium conc.), medium, or high (150%) concentrations of the proteins [human albumin (100% conc. = 7 mg L(-1)), mucin (577.5 mg L(-1)), immunoglobulin G (IgG) (46 mg L(-1)), casein isolated from bovine milk (1.2 g L(-1))] or amino acid [l-Proline (7 mg L(-1))] were added to 1 L of the demineralizing solution, whereas 1 L served as control. Mineral loss and lesion depth (LD) were evaluated from microradiographs of thin sections (110 mum) by a dedicated software package (TMR 1.24). No differences were found between the five control groups (P > 0.05; ANOVA). Albumin, l-Proline, and IgG did not affect enamel demineralization, whereas the addition of both casein and mucin resulted in significant reductions of both mineral loss and LDs (P < 0.01; Tukey's test). Within the limitations of an in vitro study, the present investigation indicates that casein and mucin seem to affect enamel demineralization significantly. Thus, these proteins might be helpful as an additive to saliva substitutes or mouthwashes if the quality of saliva is altered.

Effect of Saliva Composition on Experimental Root Caries

The aim of this study was to determine the effect of saliva composition on caries lesion development independently of the flow rate of unstimulated whole saliva (UWS) and other caries-related variables such as lesion progression time, oral hygiene level, and fluoride exposure. We hypothesized that this could be done by developing experimental root caries under carefully controlled conditions in situ in test subjects with UWS flow rates within a narrow window of normalcy. Fifteen female and 5 male subjects (66 +/- 6 years) were selected for the study according to their UWS flow rates between 0.2 and 0.4 ml/min. All subjects developed experimental root caries lesions during a 62-day period in which UWS as well as stimulated whole saliva (SWS) were repeatedly collected and analysed for flow rate, pH, buffer capacity, inorganic, and organic composition. Caries lesion development was determined by quantitative microradiography. The mean UWS flow rate was 0.30 +/- 0.05 ml/min. Significant negative correlations were obtained between UWS total phosphate concentration and mineral loss (DeltaZ; r(s) = -0.72, p < 0.001) and UWS total protein concentration and DeltaZ (r(s) = -0.70, p < 0.01). SWS and its constituents had only limited or no effect on DeltaZ. Qualitative UWS protein analysis (SDS-PAGE) revealed that subjects with low DeltaZ values had broader and more stained amylase bands than subjects with high DeltaZ values. These findings were confirmed quantitatively by HPLC. We conclude that, within a group of subjects with normal UWS flow rates, the UWS composition was more important for caries lesion development than the SWS composition. Furthermore, high UWS concentrations of phosphate, protein, and amylase were caries-protective.

Effect of Mucin Alone and in Combination with Various Dentifrices on in vitro Remineralization

The aim of this in vitro study was to evaluate the effect of combining various fluoridated dentifrices with mucin on remineralization of bovine enamel. Enamel specimens were embedded in epoxy resin, partly covered with nail varnish, and demineralized in a lactic acid solution (pH 5.0, 14 days). Parts of the demineralized areas of the specimens were then covered with nail varnish. Half of the samples were exposed to a mucin-containing (2.7 g/l) remineralizing solution, the other half to a mucin-free remineralizing solution for 30 days. In each group, the specimens were divided into four subgroups, which were brushed twice a day with a toothpaste containing sodium, stannous/amine, or amine fluoride. The specimens of the fourth subgroup were not brushed, but stored in one of the two solutions. Mineral loss and lesion depth were evaluated from microradiographs. After the remineralization period, specimens that were brushed with one of the dentifrices and stored in the mucin-containing remineralizing solution reacquired more mineral than those brushed and stored in the mucin-free solution (p < 0.05; Bonferroni post hoc test). The results indicate that mucin in combination with various fluorides seems to affect enamel remineralization significantly. Thus, mucin could be considered as an additive to saliva substitutes or mouthwashes in patients with hyposalivation.