The role of the saliva antioxidant barrier to reactive oxygen species with regard to caries development

Are salivary NO2- / NO2- and NO3- levels biomarkers for dental caries in children? Systematic review and meta-analysis

The literature is conflicting regarding salivary nitrite (NO2-)/nitrite and nitrate (NO2- and NO3-) levels in children affected by dental caries. For this reason, a systematic review to provide a consensus on the subject was propose, whose objective is to verify whether these molecules could be used as biomarkers in children with caries. A comprehensive search was performed on online database and eleven articles were included in the meta-analysis. The methodological quality of studies was assessed by Newcastle-Ottawa Scale recommended for case-control studies and by AXIS tool for cross-sectional studies. Grading of Recommendations Assessment, Development and Evaluation was used for the assessment of the certainty of the evidence for each outcome. The results showed lower NO2- levels in the group of children affected by dental caries (SMD = -2.18 [-3.24, -1.13], p < 0.01). Age, saliva collection and methods of evaluation can impact the results. When evaluating the severity of the condition, an important variation was detected in relation to the different evaluation methods NO2-/NO2- and NO3-. In conclusion, based on the evidence presented, the results suggest that NO2- levels in saliva are a possible biomarker of dental caries. Results should be evaluated with caution due to the very low evidence from primary studies. Longitudinal studies are necessary to strengthen this hypothesis.

Comparison of oral cavity protein abundance among caries-free and caries-affected individuals-a systematic review and meta-analysis

Objective

Some salivary proteins seem to be differently abundant among caries-free (CF) and caries-affected (CA) individuals, but previous results are contradictory precluding that definitive conclusion be drawn. A pooled analysis of the available evidence may provide more robust data on identifying oral cavity protein patterns among CF and CA individuals. This systematic review and meta-analysis (PROSPERO CRD42021269079) aimed to compare the oral cavity protein abundance among caries-free and caries-affected individuals.

Methods

This study was conducted following PRISMA guidelines. PubMed, Embase, and Web of Science databases were systematically assessed (up to February 2023) to retrieve clinical studies written in English, German, or in Latin-based languages that compared the oral cavity protein abundance among CF and CA individuals. Data extraction and methodological quality assessment (NIH guidelines) were independently performed by two investigators. Qualitative synthesis was performed from all included studies and meta-analysis was performed using a random-effects model with inverse variance for studies that reported the concentration of proteins or enzymatic activity. Standardized mean difference (SMD) with respective 95% confidence interval (CI) were calculated for each outcome.

Results

A total of 90 studies (two cohort and 88 cross-sectional designs) of more than 6,000 participants were selected for data extraction, being the quality of evidence graded as "fair" for most of them. The oral cavity of CF individuals presented lower total protein concentration [SMD = 0.37 (95% CI: 0.07-0.68; 18 studies)], lower total antioxidant capacity [SMD = 1.29 (95% CI: 0.74-1.85); 17 studies], and lower carbonic anhydrase activity [SMD = 0.83 (95% CI: 0.58-1.09); three studies], whereas CA individuals presented lower carbonic anhydrase concentration [SMD = -0.66 (95% CI: -1.00 to -0.32); three studies], urease [SMD = -0.95 (IC 95%: -1.72 to -0.17); four studies], and arginine deiminase system [SMD = -2.07 (95% CI: -3.53 to -0.62); three studies] activities. Antimicrobial peptides, secretory immunoglobulin-A concentrations and alpha-amylase activity were similar among individuals.

Conclusion

Differences on oral cavity protein abundance were observed among CF and CA individuals. These data indicate some protein patterns for the oral health and dental caries conditions. Even when statistically significant, some of the results were not very consistent. Cohort studies need to be conducted to validate these results.

Dental Caries and Salivary Oxidative Stress: Global Scientific Research Landscape

This study aimed to analyze the research trends on salivary oxidative stress associated with dental caries and to perform bibliometric approaches for existing publications on this association. A search was performed using the Web of Science Core Collection, without any restriction of language or publication year. The number of periodicals with the most published articles in this theme, most published authors and keywords were mapped; other metrics were also evaluated such as the countries that have more research on the subject and the period in which there were more publications on the subject. During the knowledge mapping, the most frequent experimental designs were analyzed, type of saliva collection, stage of caries disease, evaluated oxidative parameters were retrieved and analyzed from each manuscript. Between the 43 selected articles, the Journal of Clinical Pediatric Dentistry was the periodical appearing the most with 4 published articles. The authors who published the most were Celec, P., Tothova, L., Hegde, A.M., Shetty, S., Antoniali, C., and Pessan, JP with three articles each, and a total of 180 keywords representing the evolution of the theme. India and Asia were found to be the country and continent with most publications, respectively. Most articles collected non-stimulated total saliva, with total antioxidant capacity being the parameter most often evaluated. The type of study that appeared the most was cross-sectional studies, and articles published in the period of 2017-2022 were the most frequent. Studies show that dental caries can be associated to the changes in salivary oxidative biochemistry with an increase in lipid peroxidation, a biomarker of oxidative damage, and an increase in antioxidant capacity in chronic caries, in response to cariogenic challenge. Some studies evidence the reduction of lipid peroxidation after treatment of the carious lesion. Our findings reveal worldwide research trends, as well as a clearer knowledge of the evolution and future scenarios of this issue, also showing the mechanisms associating dental caries with changes in salivary oxidative biochemical parameters are not clear.

Correlation of Carbonic Anhydrase VI Enzyme, Total Proteins, Antioxidant Levels of Saliva and Dental Caries in Caries-Free and Caries-Active Children - A Case-Control Study

Background and Objectives

Factors in the biofilm influence the induction and advancement of the carious process. This study was done to relate and assess the levels of enzyme carbonic anhydrase VI, total protein, and antioxidants (superoxide dismutase [SOD], catalase, lipid peroxidase, and uric acid) in caries-free and caries-active children.

Methods

This case-control study comprised 60 children of age group 6-12 years who were evaluated for decayed missing filled teeth (dmft)/DMFT criteria and distributed into two groups: Group 1 - caries active (case) and Group 2 - caries free (control) for saliva collection with 30 participants in each of the above groups. Stimulated saliva was obtained, and the samples were then evaluated using biochemical lab tests. The data were then statistically evaluated using independent t-test.

Results

Catalase in the caries-free group was significantly higher, but the concentration of carbonic anhydrase (CAVI) enzyme, total protein, and other antioxidant enzyme activity was enhanced in caries-active children in which uric acid demonstrated a statistically significant difference with higher levels in caries-active group.

Conclusion

There is an increased concentration of CAVI enzyme in caries-active group and total protein showed a linear relation with caries activity. Antioxidant parameters such as SOD and lipid peroxidase were increased with caries activity. Uric acid was significantly higher in the caries-active group, whereas catalase showed an indirect relation with dental caries. Significant variations in the levels of these parameters imply that the levels of these components of saliva can act as strong markers of caries status in children.

Are Dental Caries Associated with Oxidative Stress in Saliva in Children and Adolescents? A Systematic Review

Background: This systematic review aimed to assess whether dental caries is associated with oxidative salivary stress. Methods: The searches were carried out in electronic databases, including PubMed, Scopus, Web of Science, the Cochrane Library, LILACS, OpenGrey, and Google Scholar, without restrictions on the date of publication and language. The acronym PECO was used, in which the participants (P) were children and adolescents exposed (E) to dental caries compared (C) to those without dental caries, with the outcome (O) of modulation of oxidative biochemical parameters. After the search retrieval, the duplicates were removed, and the articles were evaluated by title and abstract, following the inclusion and exclusion criteria. Then, the papers were read and thoroughly assessed. After selection, the risk of bias assessment and qualitative synthesis were performed using the Newcastle-Ottawa Scale (NOS) for observational studies. The Grading of Recommendations, Assessment, Development, and Evaluation (GRADE) tool was used to assess the level of evidence. Results: A total of 5790 studies were found, and 30 articles were considered eligible and were included for the qualitative synthesis and the level of evidence assessment. The studies showed an imbalance of the antioxidant and pro-oxidant parameters in individuals with dental caries, with primarily increases in both total antioxidant capacity and lipid peroxidation. Most articles showed a low risk of bias, having comparability as the main issue. When exploring through GRADE, a very low level of evidence was found. Conclusions: It was possible to observe an association between oxidative stress and dental caries, showing a disbalance of antioxidants and pro-oxidants, but the evidence level was still very low.

Evaluation of Salivary Thiol/Disulfide Homeostasis and Oxidative Stress in Children with Severe Early Childhood Caries Using a Novel Method

Objective This study aimed to assess the role of thiol/disulfide homeostasis and oxidative stress in the saliva of children with severe early childhood caries (S-ECC).

Methods Eighty children aged 3 to 6 years were involved in this case-control study. The study consisted of two groups: the study group (S-ECC) and the control group with no caries. Thiol/disulfide homeostasis and antioxidant levels were calculated after obtaining unstimulated saliva samples from all participating children.

Results The native/total thiol and total oxidant status (TOS) levels of the study group were higher than those of the control group, though not statistically significant (p > 0.05). The oxidative stress index (OSI) value was significantly higher in the study group compared to the control group (p = 0.024).

Conclusion Our results confirmed that the thiol/disulfide homeostasis was reduced, and disulfide formation, which is rereducible to thiol, was insufficient in children with S-ECC to compensate oxidative stress compared with the control group. Also, thiol levels were inadequate to compensate for oxidative stress, and thiol/disulfide homeostasis was not an independent parameter for S-ECC. Besides, the increases in the TOS level and OSI value show that oxidative stress had significant effects on S-ECC's etiopathogenesis.

Salivary biomarkers of oxidative stress in children with dental caries: Systematic review and meta-analysis

OBJECTIVE

To assess the relationship between salivary biomarkers of oxidative stress and dental caries in children.

METHODS

Studies conducted in children up to 12 years old comparing salivary biomarkers of oxidative stress such as malondialdehyde (MDA), superoxide dismutase (SOD), uric acid, and total antioxidant capacity (TAC), considering children with dental caries lesions and caries-free ones were selected. In addition, salivary parameters such as salivary flow, pH, buffering capacity, calcium and total protein levels were evaluated. A systematic literature review was carried out in 8 databases. The standardized mean difference (SMD) was measured using inverse variance as a statistical method and random effects as an analysis model, corresponding to a 95% confidence interval (CI).

RESULTS

The TAC levels were higher in children affected by dental caries compared to caries-free ones (control group), regardless of age (SMD 2.66, CI 1.33, 3.98), or gender (SMD 0.98, CI 0.56, 1.39). When adjusted for normalized protein, MDA levels were lower in the dental caries group than in the control group (SMD -16.51, CI -29.02, -4.00), and SOD levels were higher in the dental caries group (SMD 5.09, CI 0.01.10.18). The total protein concentration in saliva of children with dental caries was higher than in the control group, regardless of age (SMD 0.98, CI 0.27, 1.69), or gender (SMD 0.77, CI 0.45, 1.10). The salivary parameters assessed had lower levels in children affected by dental caries (p < 0.05).

CONCLUSIONS

The levels of oxidative stress biomarkers and salivary parameters are altered in saliva of children with dental caries.

Redefining the Cut-Off Ranges for TSH Based on the Clinical Picture, Results of Neuroimaging and Laboratory Tests in Unsupervised Cluster Analysis as Individualized Diagnosis of Early Schizophrenia

Thyroid abnormalities, including mild forms of hypothyroidism and hyperthyroidism, are reported as risk factors for the development of a number of neuropsychiatric disorders, including schizophrenia. The diagnostic process still takes into account the extreme ranges of the accepted reference values for serum TSH since the concentration of free thyroxine in the serum does not change by definition. TSH mU/L cut-off values in psychiatric patients are currently clinically considered in the case of extremely high serum TSH levels (>4.0 mU/L). The results obtained in this study suggest that the clinically significant value has a lower TSH cut-off point with an upper limit of 2–2.5 mU/L. The criteria for the differential diagnosis of patients with schizophrenia, however, mainly take into account statutory reference ranges without a background related to the history of thyroid diseases in the family. The results indicate the need to lower the upper cut-off values for TSH among patients with early psychosis, which is related to the potential clinical significance of the obtained values both in the field of clinical evaluation and neuroimaging and laboratory evaluation parameters. The cut-off points obtained with the prior available knowledge coincided with the values established in the unsupervised clustering method, which further confirms the legitimacy of their use in the individualized diagnosis strategy of schizophrenia.

Salivary Redox Biomarkers in the Course of Caries and Periodontal Disease

Caries are a pathological process of extracorporeal nature, characterized by demineralization of inorganic substances as well as proteolysis triggered by acids produced by bacteria present in dental plaque, as a result of metabolism of sugars of both external and internal origin. Periodontal disease, on the other hand, is a multifactorial degenerative disease associated with inflammation, involving a group of tissues that surround the dental cervix and root of the tooth. It is believed that one of the mechanisms in the etiopathogenesis of caries and periodontitis are disorders of local and/or general oxidative stress (OS) parameters. Numerous clinical studies have confirmed the relationship between oxidative stress markers and oral diseases. In most analyzed studies, technical and biological variability was so high that none of the markers so far has proven suitable for routine clinical use. The aim of systematic reviews of the literature is to present the existing studies on OS parameters, mainly concerning the activity of antioxidant enzymes in saliva of patients with caries and periodontitis.

Differences in Sweet Taste Perception and Its Association with the Streptococcus mutans Cariogenic Profile in Preschool Children with Caries

The aim of the study was to verify the hypothesis about differences in sweet taste perception in the group of preschool children with and without caries, and to determine its relationship with cariogenic microbiota and the frequency of sweets consumption in children. The study group included of 63 children aged 2–6 years: 32 with caries and 31 without caries. The study consisted of collecting questionnaire data and assessment of dental status using the decayed, missing, filled in primary teeth index (dmft) and the International Caries Detection and Assessment System (ICDAS II). The evaluation of sweet taste perception was carried out using a specific method that simultaneously assessed the level of taste preferences and the sensitivity threshold for a given taste. The microbiological analysis consisted of the assessment of the quantitative and qualitative compositions of the oral microbiota of the examined children. The sweet taste perception of children with caries was characterized by a lower susceptibility to sucrose (the preferred sucrose solution concentration was >4 g/L) compared to children without caries (in the range ≤ 4 g/L, p = 0.0015, chi-square test). A similar relationship was also observed for frequent snacking between meals (p = 0.0038, chi-square test). The analysis of studied variables showed the existence of a strong positive correlation between the perception of sweet taste and the occurrence and intensity of the cariogenic process (p = 0.007 for dmft; and p = 0.012 for ICDAS II), as well as the frequency of consuming sweets (p ≤ 0.001 for frequent and repeated consumption of sweets during the day, Spearman test) in children with caries. Additionally, children with an elevated sucrose taste threshold were more than 10-times more likely to develop S. mutans presence (OR = 10.21; 95% CI 3.11–33.44). The results of this study suggest the future use of taste preferences in children as a diagnostic tool for the early detection of increased susceptibility to caries through microbial dysbiosis towards specific species of microorganisms.

Carious Lesion Severity Induces Higher Antioxidant System Activity and Consequently Reduces Oxidative Damage in Children's Saliva

Oxidative stress biomarkers can be found at detectable concentrations in saliva. These salivary biomarkers reflect specific oxidation pathways associated with caries and periodontitis. Our study evaluated the influence of dental caries severity (assessed using the ICCMS™ criteria) on the levels of oxidative stress biomarkers in saliva from children. Unstimulated saliva samples were collected from patients (from one to three years old) in a day care center in Birigui, SP, Brazil, two hours after fasting. Children were divided into four groups (n = 30/group), according to caries severity: caries free (group A), early carious lesions (group B), moderate carious lesions (group C), and advanced carious lesions (group D). The following salivary biomarkers were determined: total proteins (TP), measured by the Lowry method; oxidative damage, measured by the TBARS method; total antioxidant capacity (TAC); superoxide dismutase (SOD) enzymatic antioxidant activity; and uric acid (UA) non-enzymatic antioxidant activity. Data were analyzed by ANOVA, followed by the Student-Newman-Keuls test, Pearson and Spearman correlation coefficients, and multivariable linear regression (p < 0.05). TP, TAC, SOD enzymatic antioxidant activity, and UA non-enzymatic antioxidant activity increased with caries severity, consequently reducing salivary oxidative damage. It was concluded that higher caries severity increases salivary antioxidant system activity, with consequent reduction in salivary oxidative damage.

The Significance of Lactoperoxidase System in Oral Health: Application and Efficacy in Oral Hygiene Products

Lactoperoxidase (LPO) present in saliva are an important element of the nonspecific immune response involved in maintaining oral health. The main role of this enzyme is to oxidize salivary thiocyanate ions (SCN^-) in the presence of hydrogen peroxide (H₂O₂) to products that exhibit antimicrobial activity. LPO derived from bovine milk has found an application in food, cosmetics, and medical industries due to its structural and functional similarity to the human enzyme. Oral hygiene products enriched with the LPO system constitute an alternative to the classic fluoride caries prophylaxis. This review describes the physiological role of human salivary lactoperoxidase and compares the results of clinical trials and in vitro studies of LPO alone and complex dentifrices enriched with bovine LPO. The role of reactivators and inhibitors of LPO is discussed together with the possibility of using nanoparticles to increase the stabilization and activity of this enzyme.

Caries reporting in studies that used the International Caries Detection and Assessment System: A scoping review

OBJECTIVE

To explore how caries was reported in studies that employed the International Caries Detection and Assessment System (ICDAS).

METHODS

A systematic database search up to August 2017 was carried out using PubMed, Ovid MEDLINE, Cochrane library and ISI Web of Science electronic databases. Only studies that used the ICDAS for dental caries examinations were included. Studies were excluded if the examination was done only for the validation or the calibration of the ICDAS and/or if the examination was not done for the whole dentition. Measures used to report caries were considered.

RESULTS

A total of 126 papers met the inclusion criteria. Forty-four different synthesis measures were used to report caries. Most of the studies used a combination of multiple measures to report patient's caries level. These reporting measures cluster into four main groups: the number of individual ICDAS scores (ie, total counts of every score); the number of decayed surfaces/teeth (ie, total counts of combined caries scores for surfaces or teeth); measures of caries experience (ie, total counts of combined caries scores, filled and/or missing surfaces or teeth); and measures of central tendency and dispersion. The number of decayed surfaces and individual ICDAS scores were the most commonly used measures. Three studies used mean ICDAS score (ie, total ICDAS scores divided by the number of teeth), two used mean ICDAS score of carious teeth (ie, total ICDAS scores divided by the number of carious teeth) and two used the maximum ICDAS score (ie, highest ICDAS score recorded). The total ICDAS score was used only once. Many studies synthesized from the ICDAS the number of decayed, missing and filled teeth/surfaces (dmft/DMFT, dmfs/DMFS) as a measure of caries experience.

CONCLUSIONS

There are variations among studies in the utilization of the system to summarize caries. Most studies presented caries data using the categorical characteristics of the ICDAS.

Comparison of Salivary Antioxidants in Children with Primary Tooth Abscesses before and after Treatment in Comparison with Healthy Subjects

Aim:

The aim of this study was to compare the total antioxidant capacity (TAC) of children with primary molar abscesses before and two weeks after extraction of the infected tooth.

Materials and methods:

Forty one children aged between 3-6 years participatesd in this cross sectional study. The antioxidant activity of saliva was investigated in 20 patients with tooth abscesses affecting one of the first primary molars before and after tooth extraction in the case group and once in 21 children with no caries or dental problems in the control group. The FRAP (ferric reduction antioxidant power) method was used to measure the antioxidant power of salivary samples and TAC values were calculated. Data were analyzed with SPSS Version 16 using the paired t-test at a significance level of 0.05.

Results:

The mean antioxidant index increased in children after (509.2 ± 138.4) treatment (before 483.4 ± 183.6), but this difference was not significant (P=0.61). Also, there was no difference in the mean antioxidant index in control group (494.5±147.9) compared the study group before (P=0.83) and after (P=0.75) treatment.

Conclusion:

Under the conditions of this study the total antioxidant capacity of saliva was not compromised in children with abscessed teeth.

Relationship between Pyruvate Kinase Activity and Cariogenic Biofilm Formation in Streptococcus mutans Biotypes in Caries Patients

Streptococcus mutans (MS) and its biotype I are the strains most frequently found in dental plaque of young children. Our results indicate that in children pyruvate kinase (PK) activity increases significantly in dental plaque, and this corresponds with caries progression. The MS strains isolated in this study or their main glycolytic metabolism connected with PK enzymes might be useful risk factors for studying the pathogenesis and target points of novel therapies for dental caries. The relationship between PK activity, cariogenic biofilm formation and selected biotypes occurrence was studied. S. mutans dental plaque samples were collected from supragingival plaque of individual deciduous molars in 143 subjects. PK activity was measured at different time points during biofilm formation. Patients were divided into two groups: initial stage decay, and extensive decay. Non-parametric analysis of variance and analysis of covariance were used to determine the connections between S. mutans levels, PK activity and dental caries biotypes. A total of 143 strains were derived from subjects with caries. Biotyping data showed that 62, 23, 50, and 8 strains were classified as biotypes I, II, III, IV, respectively. PK activity in biotypes I, II, and IV was significantly higher in comparison to that in biotype III. The correlation between the level of S. mutans in dental plaque and PK activity was both statistically significant (p < 0.05) and positive. The greater the level of S. mutans in the biofilm (colony count and total biomass), the higher the PK activity; similarly, a low bacterial count correlated with low PK activity.