Differential effects of total and partial sleep deprivation on salivary factors in Wistar rats

ObjectiveAim of this study was to investigate the effects of sleep deprivation on salivary factors in rats.DesignAnimals were randomly assigned into three groups of 6 animals each as control, total sleep deprivation (TSD) and partial sleep deprivation (PSD) groups. The multiple platform method was used to induce partial and total sleep deprivation for 7 days. On the 8th day, stimulated saliva samples were collected for the analysis of salivary lag time, flow rate, salivary amylase activity, immunoglobulin A secretion rate and corticosterone levels using ELISA and standard kinetic enzyme assay. Data were analyzed using ANOVA with Dunnett T3 post hoc tests.ResultsSalivary flow rate reduced significantly in the TSD group compared with the PSD group as well as the control group (p = 0.01). The secretion rate of salivary IgA was significantly reduced in the TSD group compared with the control group (p = 0.04). Salivary amylase activity was significantly elevated in the TSD group compared with the PSD group as well as control group (p < 0.001). However, there were no significant changes in the salivary lag time and levels of corticosterone among the groups.ConclusionsThese findings suggest that total sleep deprivation is associated with reduced salivary flow rate and secretion rate of IgA as well as elevated levels of salivary amylase activity in rats. However, sleep recovery of four hours in the PSD group produced ameliorative effects on the impaired functions of salivary glands.     

Effects of polyphosphates and fluoride on hydroxyapatite dissolution: A pH-stat investigation

ObjectivesThis study investigated the immediate and sustained effect of sodium trimetaphosphate (TMP) and sodium hexametaphosphate (HMP) associated or not with fluoride (F) on hydroxyapatite (HA) dissolution using an erosion-like model, considering as well as the influence of salivary coating.DesignBaseline dissolution rates were determined for HA discs using a pH-stat system. In the first set of experiments, HA discs were treated with 1100 μg F/mL, 1% or 8% of HMP, 1% or 8% of TMP and 1100 μg F/mL associated with 1% or 8% of HMP or TMP, totaling 9 groups (n = 8). In a second phase, HA discs were kept in pooled human saliva at 37 °C for 2 h before treatment with deionised water and 1100 μg F/mL associated with 1% or 8% of HMP or TMP, totaling 5 groups (n = 8). The post-treatment dissolution rate was determined from three consecutive 30-min assays. Data were analysed using 2 and 3-way ANOVA followed by Fisher and Holm–Sidak methods, respectively (α = 0.05).ResultsAll test solutions promoted reduction in HA dissolution rate when compared to baseline control in the first post-treatment run (p < 0.001). However, a synergistic effect was only observed between fluoride and 1% HMP. Moreover, the duration of inhibitory effect was greater when 8% HMP and 1 or 8% HMP associated with F were assessed (p < 0.001). The presence of salivary coating led to higher protection for all groups when compared to discs without coating (p < 0.001).ConclusionThe reduction of HA dissolution rate, as well as the duration of this effect were influenced by fluoride, type and concentration of phosphate salt and the presence of a salivary coating.     

Salivary levels of calcium,phosphorus, potassium,albumin and correlation with serum biomarkers in hemodialysis patients

ObjectivesEvidences suggest that hemodialysis patients have reduced salivary flow and changes in the composition of salivary secretion. These changes may reflect local and systemic disorders. The objectives of this study were to compare the salivary levels of calcium (Ca), phosphorus (P), potassium (K) and albumin in hemodialysis patients and healthy subjects, and to investigate a possible correlation between their serum and salivary levels.DesignA case–control study was conducted with 60 hemodialysis patients (HD group) and 37 systemically healthy individuals (control group). Stimulated saliva samples were collected for biochemical analysis (Ca, P, K and albumin). Serum data were collected in the HD group. Statistical analysis included t-test, Pearson correlation and simple linear regression.ResultsThe HD group exhibited higher salivary levels of Ca, P, and albumin (p < 0.05). There was a significant positive correlation between serum PTH and salivary phosphorus (r = 0.342, p = 0.009), and between serum PTH and salivary potassium (r = 0.306, p = 0.020). An increase of 100 pg/dL in serum PTH was associated with an elevation of salivary P levels (0.34 mg/dL, p = 0.009), and salivary K levels (0.20 mmol/dL, p = 0.02), in the HD group.ConclusionsThe findings suggest that HD patients present increased levels of salivary components (Ca, P, and albumin), and changes commonly observed in HD patients, such as hyperparathyroidism, appear to have an influence on salivary composition.     

In vitro dentine remineralization with a potential salivary phosphoprotein homologue

ObjectiveAdvantages of introducing a salivary phosphoprotein homologue under standardized in vitro conditions to simulate the mineral-stabilizing properties of saliva have been proposed. This study longitudinally investigates the effects of casein, incorporated as a potential salivary phosphoprotein homologue in artificial saliva (AS) solutions with/without fluoride (F) on in vitro dentine lesion remineralization.DesignThin sections of bovine root dentine were demineralized and allocated randomly into 6 groups (n = 18) having equivalent mineral loss (ΔZ) after transverse microradiography (TMR). The specimens were remineralized using AS solutions containing casein 0 μg/ml, F 0 ppm (C₀–F₀); casein 0 μg/ml, F 1 ppm (C₀–F₁); casein 10 μg/ml, F 0 ppm (C₁₀–F₀); casein 10 μg/ml, F 1 ppm (C₁₀–F₁); casein 100 μg/ml, F 0 ppm (C₁₀₀–F₀) or casein 100 μg/ml, F 1 ppm (C₁₀₀–F₁) for 28 days with TMR taken every 7 days.ResultsSurface mineral precipitation, evident in group C₀–F_1, was apparently inhibited in groups with casein incorporation. Repeated measures ANOVA with Bonferroni correction revealed higher ΔZ for non-F and non-casein groups than for their counterparts (p < 0.001). Subsequent multiple comparisons showed that mineral gain was higher (p < 0.001) with 10 μg/ml casein than with 100 μg/ml when F was present in the earlier stages of remineralization, with both groups achieving almost complete remineralization after 28 days.ConclusionCasein is a potential salivary phosphoprotein homologue that could be employed for in vitro dentine remineralization studies. Concentration related effects may be clinically significant and thus must be further examined.     

Randomized clinical trial on effectiveness of silver diamine fluoride and glass ionomer in arresting dentine caries in preschool children

ObjectiveTo compare the effectiveness of annual topical application of silver diamine fluoride (SDF) solution, semi-annual topical application of SDF solution, and annual application of a flowable high fluoride-releasing glass ionomer in arresting active dentine caries in primary teeth.MethodsA total of 212 children, aged 3–4 years, were randomly allocated to one of three groups for treatment of carious dentine cavities in their primary teeth: Gp1-annual application of SDF, Gp2-semi-annual application of SDF, and Gp3-annual application of glass ionomer. Follow-up examinations were carried out every six months to assess whether the treated caries lesions had become arrested.ResultsAfter 24 months, 181 (85%) children remained in the study. The caries arrest rates were 79%, 91% and 82% for Gp1, Gp2 and Gp3, respectively (p = 0.007). In the logistic regression model using GEE to adjust for clustering effect, higher caries arrest rates were found in lesions treated in Gp2 (OR = 2.98, p = 0.007), those in anterior teeth (OR = 5.55, p < 0.001), and those in buccal/lingual smooth surfaces (OR = 15.6, p = 0.004).ConclusionAnnual application of either SDF solution or high fluoride-releasing glass ionomer can arrest active dentine caries. Increasing the frequency of application to every 6 months can increase the caries arrest rate of SDF application.Clinical significanceArrest of active dentine caries in primary teeth by topical application of SDF solution can be enhanced by increasing the frequency of application from annually to every 6 months, whereas annual paint-on of a flowable glass ionomer can also arrest active dentine caries and may provide a more aesthetic outcome.     

Probiotic intervention influences the salivary levels of Matrix Metalloproteinase (MMP)-9 and Tissue Inhibitor of metalloproteinases (TIMP)-1 in healthy adults

ObjectiveTo study the effect of orally administered Bifidobacterium animalis subsp. lactis BB-12 and Lactobacillus rhamnosus GG on the salivary levels of Matrix Metalloproteinases (MMP)-8, MMP-9 and of Tissue Inhibitor of Metalloproteinases (TIMP)-1 in healthy adults. Furthermore, the correlations between MMP-8, MMP-9 and TIMP-1 and plaque and gingival indices, salivary mutans streptococci and lactobacilli counts, and stimulated saliva secretion rate were analysed.DesignThe salivary samples originated from a randomized controlled trial where healthy student volunteers consumed probiotic or placebo lozenges twice a day for four weeks. The saliva samples were collected and clinical parameters measured at the baseline and at the end of the original study. For this study, the salivary levels of MMP-8, MMP-9 and TIMP-1 were analysed with immunofluorometric assay (IFMA) and enzyme-linked immunosorbent assay (ELISA).ResultsIn the probiotic group (n = 29), salivary MMP-9 levels increased (p < 0.01) and TIMP-1 levels decreased (p < 0.01) significantly during the intervention. Furthermore, MMP-9/TIMP-1 ratio differed significantly from the baseline level (p < 0.01). These changes were not observed in the control group (n = 31). In the whole data, salivary MMP-9 and gingival index correlated (r = 0.260, p < 0.05 at baseline and r = 0.354, p < 0.01 at the end of the study). Intergroup differences or correlations with other clinical parameters were not found. Probiotic consumption did not affect the saliva flow rate.ConclusionsIncreased MMP-9 and decreased TIMP-1 levels in saliva may indicate that probiotics have immunomodulatory effects in the oral cavity. Furthermore, increased salivary MMP-9 levels may be an indication of the defensive potential of matrix metalloproteinases.     

Fabrication and characterization of remineralizing dental composites containing calcium type pre-reacted glass-ionomer (PRG-Ca) fillers

ObjectiveTo fabricate and characterize dental composites with calcium type pre-reacted glass-ionomer (PRG-Ca) fillers.MethodsPRG-Ca fillers were prepared by the reaction of calcium fluoroaluminosilicate glass with polyacrylic acid. Seven dental composites were produced from the same organic matrix (70/30 wt% Bis-GMA/TEGDMA), with partial replacement of barium borosilicate (BaBSi) fillers (60 wt%) by PRG-Ca fillers (wt%): E0 (0) – control, E1 (10), E2 (20), E3 (30), E4 (40), E5 (50) and E6 (60). Enamel remineralization was evaluated in caries-like enamel lesions induced by S. mutans biofilm using micro-CT. The following properties were characterized: degree of conversion (DC%), roughness (Ra), Knoop hardness (KHN), flexural strength (FS), flexural modulus (FM), water sorption (W_sp), water solubility (W_sl), and translucency (TP). Data were analyzed to one-way ANOVA and Tukey’s HSD test (α = 0.05).ResultsAll composites with PRG-Ca induced enamel remineralization. E0 and E1 presented similar and highest DC% than E2 = E3 = E4 = E5 = E6. Ra and KHN were not influenced by PRG-Ca fillers (p < 0.05). The higher the content of PRG-Ca, the lower FS, FM and TP (p < 0.05). W_sp increased linearly with the content of PRG-Ca fillers (p < 0.05). E6 presented the highest W_sl (p < 0.05), while the W_sl of the other composites were not different from each other (p > 0.05).SignificanceIncorporation of 10–40 wt.% of PRG-Ca fillers endowed remineralizing potential to dental composites without jeopardizing the overall behavior of their physicochemical properties. Dental composites with PRG-Ca fillers seems to be a good alternative for reinforcing the enamel against caries development.     

Sodium fluoride effect on erosion–abrasion under hyposalivatory simulating conditions

ObjectivesTo investigate the effect of fluoride (0, 275 and 1250 ppm F; NaF) in combination with normal and low salivary flow rates on enamel surface loss and fluoride uptake using an erosion–remineralization–abrasion cycling model.DesignEnamel specimens were randomly assigned to 6 experimental groups (n = 8). Specimens were individually placed in custom made devices, creating a sealed chamber on the enamel surface, connected to a peristaltic pump. Citric acid was injected into the chamber for 2 min followed by artificial saliva at 0.5 (normal flow) or 0.05 (low flow) ml/min, for 60 min. This cycle was repeated 4×/day, for 5 days. Toothbrushing with abrasive suspensions containing fluoride was performed for 2 min (15 s of actual brushing) 2×/day. Surface loss was measured by optical profilometry. KOH-soluble fluoride and enamel fluoride uptake were determined after the cycling phase. Data were analysed by two-way ANOVA.ResultsNo significant interactions between fluoride concentration and salivary flow were observed for any tested variable. Low caused more surface loss than normal flow rate (p < 0.01). At both flow rates, surface loss for 0 was higher than for 275, which did not differ from 1250 ppm F. KOH-soluble and structurally-bound enamel fluoride uptake were significantly different between fluoride concentrations with 1250 > 275 > 0 ppm F (p < 0.01).ConclusionsSodium fluoride reduced enamel erosion/abrasion, although no additional protection was provided by the higher concentration. Higher erosion progression was observed in low salivary flow rates. Fluoride was not able to compensate for the differences in surface loss between flow rates.     

The association of Enamelin,Lactoferrin, and Tumour necrosis factor alpha gene polymorphisms with high caries susceptibility in Chinese children under 4 years old

ObjectiveThe aim of this study was to assess the role of ENAM rs3796703, LTF rs1126478, and TNF-α rs1800629 in high caries susceptibility.DesignThe present case–control study included 1005 unrelated children under 4 years old: 505 with severe caries (dmft index ≥4) and 500 who were caries-free (dmft index = 0 and without white-spot lesions). Questionnaires were obtained from parents and gardians about the children’s diet and oral behavioural habits. All the children received dental examinations and oral swabbing for human genomic DNA collection. ENAM rs3796703, LTF rs1126478, and TNF-α rs1800629 were genotyped by Sanger sequencing.ResultsThe frequency of the ENAM rs3796703 T allele (6.7% in the caries group and 4.2% in the caries-free group), CT genotype (12.7% in the caries group and 8.4% in the caries-free group), TNF-α rs1800629 A allele (4.8% in the caries group and 6.8% in the caries-free group), and AG genotype (8.7% in the caries group and 13.2% in the caries-free group) were significantly different between the caries and caries-free groups (p < 0.05). No significant difference was found in the LTF rs1126478 allele frequency and genotype distribution between the two groups. The ENAM rs3796703 CT genotype increased caries susceptibility by 60.9% compared to the CC genotype (β = 0.746, OR = 1.609), and the TNF-α rs1800629 AG genotype reduced caries susceptibility by 47.4% compared to the GG genotype (β = −0.642, OR = 0.526). In terms of habits covariates, prolongation of night feeding time by 1 month increased caries susceptibility by 3.3% (β = 0.033, OR = 1.033); additionally, sweets and acidic drinks consumption 1–2 times per day increased caries susceptibility by 218.2% (β = 1.158, OR = 3.182), and consumption 3 or more times pe/r day increased susceptibility by 883.5% (β = 2.286, OR = 9.835) compared to non-consumption. Topical fluoride application decreased caries susceptibility by 43.0% (β = −0.562, OR = 0.570).ConclusionsThe ENAM and TNF-α genes are likely associated with caries experience in Chinese children. The ENAM rs3796703 CT genotype might be involved in caries susceptibility, while TNF-α rs1800629 AG genotype might be involved in caries protection.     

Calcium and phosphate ion releasing composite: Effect of pH on release and mechanical properties

ObjectivesSecondary caries and restoration fracture are the two main challenges facing tooth cavity restorations. The objective of this study was to develop a composite using tetracalcium phosphate (TTCP) fillers and whiskers to be stress-bearing, and to be “smart” to increase the calcium (Ca) and phosphate (PO₄) ion release at cariogenic pH.MethodsTTCP was ball-milled to obtain four different particle sizes: 16.2, 2.4, 1.3, and 0.97 μm. Whiskers fused with nano-sized silica were combined with TTCP as fillers in a resin. Filler level mass fractions varied from 0 to 75%. Ca and PO₄ ion releases were measured vs. time at pH of 7.4, 6, and 4. Composite mechanical properties were measured via three-point flexure before and after immersion in solutions at the three pH.ResultsTTCP composite without whiskers had flexural strength similar to a resin-modified glass ionomer (Vitremer) and previous Ca–PO₄ composites. With whiskers, the TTCP composite had a flexural strength (mean ± S.D.; n = 5) of (116 ± 9) MPa, similar to (112 ± 14) MPa of a stress-bearing, non-releasing hybrid composite (TPH) (p > 0.1). The Ca release was (1.22 ± 0.16) mmol/L at pH of 4, higher than (0.54 ± 0.09) at pH of 6, and (0.22 ± 0.06) at pH of 7.4 (p < 0.05). PO₄ release was also dramatically increased at acidic pH. After immersion, the TTCP–whisker composite matched the strength of TPH at all three pH (p > 0.1); both TTCP–whisker composite and TPH had strengths about threefold that of a releasing control.SignificanceThe new TTCP–whisker composite was “smart” and increased the Ca and PO₄ release dramatically when the pH was reduced from neutral to a cariogenic pH of 4, when these ions are most needed to inhibit caries. Its strength was two- to threefold higher than previously known Ca–PO₄ composites and resin-modified glass ionomer. This composite may have the potential to provide the necessary combination of load-bearing and caries-inhibiting capabilities.     

Sex differentials in caries frequencies in Medieval London

ObjectiveTooth decay is one of the most common oral infections observed in skeletal assemblages. Sex differentials in caries frequency are commonly examined, with most studies finding that females tend to have a higher frequency of carious lesions (caries) compared to males. Less research has examined differences in caries between males and females with respect to age in past populations. Findings from living populations indicate that caries frequencies are higher in females, at least in part, because of the effects of estrogen and pregnancy. We are interested in the interaction of age, sex, and caries in medieval London, during a period of repeated famines, which might have exacerbated underlying biological causes of caries sex differentials.DesignWe examined caries in adults from two medieval London cemeteries dating to c. 1120–1539 AD: St. Mary Spital (n = 291) and St. Mary Graces (n = 80) to test the hypothesis that males and females have different caries frequencies irrespective of age. The association between maxillary molar caries and sex was tested using hierarchical log-linear analysis to control for the effects of age on caries frequencies.ResultsThe results indicate a higher frequency of maxillary molar caries in females (P < 0.00), and that the age distribution of caries differs between the sexes (P = 0.01), with a consistent increase in frequency with age for females until late adulthood, but not males.ConclusionsThe difference in caries frequencies is not explained by differences in the age distributions of the sexes. Differences in the age patterns of caries for males and females could be the result of biological factors that present during reproductive age, differences in diet, or differential access to resources during famine.     

Association of thalassemia major and gingival inflammation: A pilot study

ObjectivesThis cross-sectional study aimed to investigate the relationship between thalassemia major (TM) and gingival inflammation through the salivary, serum, and gingival crevicular fluid (GCF) levels of matrix metalloproteinase (MMP)-8, MMP-9 and tissue inhibitor of MMP (TIMP)-1.MethodsBiofluid samples and full-mouth clinical periodontal recordings were obtained from 29 otherwise healthy patients with TM and 25 systemically healthy (SH) individuals. Biofluid samples were evaluated by immunofluorometric assay (IFMA) and enzyme-linked immunoassays (ELISAs). Data were tested statistically by Kolmogorov Simirnov, Mann–Whitney U tests, Spearman correlation analysis.ResultsAge, smoking status, bleeding on probing, plaque index were similar in the study groups, but probing depth, gender data exhibited significant differences (p = 0.037 for both). Salivary MMP-8, MMP-9, TIMP-1 concentrations were significantly higher in the TM than SH group (p = 0.014; p < 0.001; p = 0.042, respectively). Serum TIMP-1 concentrations were significantly higher; MMP-8/TIMP-1, MMP-9/TIMP-1 molar ratios were significantly lower in the TM than SH group (p < 0.001; p = 0.005; p = 0.022, respectively). Very few GCF samples revealed biochemical data above the detection limits. Numerous correlations were found between clinical periodontal parameters and biochemical data.ConclusionsIt may be suggested that TM may exacerbate the local inflammatory response as manifested in salivary MMP-8, MMP-9, TIMP-1 levels.     

Relationship between the IgA antibody response against Streptococcus mutans GbpB and severity of dental caries in childhood

ObjectiveExplore the associations between the severity of dental caries in childhood, mutans streptococci (MS) levels and IgA antibody response against Streptococcus mutans GbpB. Moreover, other caries-related etiological factors were also investigated.Design36–60 month-old children were grouped into Caries-Free (CF, n = 19), Early Childhood Caries (ECC, n = 17) and Severe Early Childhood Caries (S-ECC, n = 21). Data from socio-economic-cultural status, oral hygiene habits and dietary patterns were obtained from a questionnaire and a food-frequency diary filled out by parents. Saliva was collected from children for microbiological analysis and detection of salivary IgA antibody reactive with S. mutans GbpB in western blot.ResultsS-ECC children had reduced family income compared to those with ECC and CF. There was difference between CF and caries groups (ECC and S-ECC) in MS counts. Positive correlations between salivary IgA antibody response against GbpB and MS counts were found when the entire population was evaluated. When children with high MS counts were compared, S-ECC group showed significantly lower IgA antibody levels to GbpB compared to CF group. This finding was not observed for the ECC group.ConclusionsThis study suggests that children with S-ECC have reduced salivary IgA immune responses to S. mutans GbpB, potentially compromising their ability to modify MS infection and its cariogenic potential. Furthermore, a reduced family income and high levels of MS were also associated with S-ECC.     

A randomized controlled trial by the 3DS for dental caries

The aim of this study is to evaluate the povidone-iodine for the suppression of oral cariogenic bacteria and compare its effects to that of fluoride in children. We carried out a randomized controlled trial to compare the effects of povidone-iodine to those for sodium fluoride. Pre-school children (n = 210) with more than 10⁵ cfu/ml mutans streptococci in their stimulated saliva were randomly sampled and randomly allocated into three groups. We planned the preventive program by 3DS (Dental Drag Delivery System). The groups that provided preventive programs were the povidone-iodine group (n = 70) and the sodium fluoride group (n = 70). A control group (n = 70) received no intervention. Povidone-iodine or sodium fluoride was applied to the tooth surface using custom made trays. Subsequent home care was obligatory for one month. After one month, the salivary levels of mutans streptococci were low level when compared to the based data. However the difference in salivary levels of mutans streptococci among groups was not statistically significant when comparing the povidone-iodine group with the sodium fluoride group (P = 0.625). After 2.5 years follow up, differences in incidence of new dental caries among the three groups were not statistically significant (P = 0.583). Clinical application of anti-microbial drugs may be effective, but only a single intervention is not sufficient to reduce the incidence of new dental caries.     

Immunohistochemical investigations on the expression of programmed cell death ligand 1, human leukocyte antigens G and E,and granzyme B in intraoral mucoepidermoid carcinoma

ObjectiveTo identify the expression of nonclassical human leukocyte antigen G and E (HLA-G and -E), programmed cell death ligand-1 (PD-L1) and granzyme B (GB) in intraoral mucoepidermoid carcinomas (MECs), and to assess whether such expressions are related to metastasis, survival, staging, tumor grade and number of GB-positive cells.DesignFor this cross-sectional study, samples of MEC (n = 30) were selected and classified as low-grade (LG), intermediate-grade (IG) or high-grade (HG), according to the WHO grading system. HLA-G, -E and PD-L1 were identified by immunohistochemistry and quantified as the proportion of positive neoplastic cells. The density of GB+ cells was also evaluated. The Kruskal-Wallis test was used with a 5% significance level.ResultsExpressions of HLA-G, -E and PD-L1 were identified in the majority of epidermoid, intermediate and clear cells, but not in the mucous cells of the MECs. The quantitative analysis of the total percentage of positive neoplastic cells showed overexpression of this set of proteins in all MEC samples. The expression of these proteins and histological grading were positively correlated [HLA-G (LG = 79% positive cells, IG = 96%, HG = 99%; p = 0.0004), HLA-E (LG = 70%, IG = 96%, HG = 99%; p < 0.0001) and PD-L1 (LG = 34%, IG = 79%, HG = 80%; p = 0.01)]. No relationship was observed between the immunosuppressive proteins and other clinicopathological parameters. Low GB density was found in all MEC samples.ConclusionsThe augmented expression of HLA-G, -E and PD-L1 in the intraoral MEC might suggest a role of these molecules in the scape of neoplastic cells from immunosurveillance.     

Antimicrobial peptides in saliva of children with severe early childhood caries

ObjectiveControversies exist regarding the relationship between the concentrations of antimicrobial peptides (AMPs) and presence of dental caries in children. Thus, the aim of this study was to examine levels of AMPs in saliva of caries-free (CF), early childhood caries (ECC) and severe early childhood caries (S-ECC) children to determine if the levels of these salivary peptides individually or in combinations were related to caries severity and mutans streptococci levels.Design36 to 60 month-old children were selected to participate in this study. Children were grouped into CF group (n = 29), ECC group (n = 25) and S-ECC group (n = 29). Saliva was collected from children for microbiological analysis by culture. Salivary concentrations of cathelicidin LL-37, human β-defensin 2 (hBD-2), human β-defensin 3 (hBD-3) and histatin-5 (HTN-5) were determined by ELISA.ResultsSalivary concentrations of AMPs did not differ among CF, ECC and S-ECC groups. Data showed positive correlations between mutans streptococci levels and salivary hBD-2 or HTN-5. Positive correlations were found between hBD-2, hBD-3, LL-37 and HTN-5. Combinations among AMPs, mainly LL-37, were positively associated with caries levels.ConclusionsSalivary concentrations of AMPs individually were not associated with the severity of early childhood caries. The stimulus of caries appears to trigger a biological response, however, with a combination of these peptides.     

A new optical detection method to assess the erosion inhibition by in vitro salivary pellicle layer

ObjectivesApplication of the recently developed optical method based on the monitoring of the specular reflection intensity to study the protective potential of the salivary pellicle layer against early enamel erosion.MethodsThe erosion progression was compared between two treatment groups: enamel samples coated by the 15 h-in vitro-formed salivary pellicle layer (group P, n = 90) and the non-coated enamel surfaces (control group C, n = 90). Different severity of the erosive impact was modelled by the enamel incubation in 1% citric acid (pH = 3.6) for 2, 4, 8, 10 or 15 min. Erosion quantification was performed by the optical method as well as by the microhardness and calcium release analyses.ResultsOptical assessment of the erosion progression showed erosion inhibition by the in vitro salivary pellicle in short term acidic treatments (≤4 min) which was also confirmed by microhardness measurements proving significantly less (p < 0.05) enamel softening in the group P at 2 and 4 min of erosion compared to the group C. SEM images demonstrated less etched enamel interfaces in the group P at short erosion durations as well.ConclusionsMonitoring of the specular reflection intensity can be successfully applied to quantify early erosion progression in comparative studies. In vitro salivary pellicle (2 h) provides erosion inhibition but only in short term acidic exposures.Clinical significanceThe proposed optical technique is a promising tool for the fast and non-invasive erosion quantification in clinical studies.     

Translucency,flexural strength,fracture toughness,fracture load of 3-unit FDPs,Martens hardness parameter and grain size of 3Y-TZP materials

ObjectiveThis investigation tested pre-shaded 3Y-TZP materials on optical, mechanical and structural properties and calculated correlations between these properties.MethodsSeven A2-shaded 3Y-TZP zirconia materials were investigated on translucency (T) via UV–vis-spectrophotometer, fracture load of 3-unit FDPs (FL), biaxial flexural strength (FS), Chevron-Notch Beam (CNB), fracture toughness (K_IC) and Martens parameter (hardness: HM and indentation modulus: E_IT). FL, FS and K_IC were measured in a universal testing machine. The grain size was evaluated by scanning electron microscopy (SEM). Data was analyzed using one-way ANOVA followed by post hoc Scheffé, Kruskal–Wallis-, Mann–Whitney-U- and Pearson-test (p < 0.05).ResultsFor translucency, negative correlations were found with results of facture load (R = −0.444, p < 0.001) and K_IC (R = −0.503, p < 0.001). While a positive correlation was found between translucency and flexural strength (R = 0.238, p = 0.019), between fracture load and E_IT (R = 0.227, p < 0.029), between fracture load and K_IC (R = 0.362, p < 0.001) as well as between fracture load and the grain size (R = 0.598, p = 0.007). While the grain size positively correlated with E_IT (R = 0.534, p = 0.017) as well as E_IT with HM (R = 0.720, p < 0.001).SignificanceDespite of being based on the same raw material, tested zirconia materials significantly differed regarding optical, mechanical (except biaxial flexural strength and Martens hardness) and structural properties. Materials with highest optical properties were those with lowest mechanical properties (CER, COP).     

The effect of surface defects in early caries assessment using quantitative light-induced fluorescence (QLF) and micro-digital-photography (MDP)

ObjectivesThe purpose of this study was to consider the impact of surface defects on quantitative light-induced fluorescence (QLF) and micro-digital-photography (MDP) measures, in relationship to lesion depth.MethodsSimulated enamel carious lesions were developed on 45 extracted human teeth. Images of each tooth were captured with both QLF and MDP. The teeth were sectioned and lesion depth was measured with polarized light microscopy (PLM). Pearson correlations were computed using data from the 27 lesions which did not have surface loss, and then separately based upon the 18 lesions which did display surface loss. MDP variables ΔR and ΔX measure reflected light, whereas QLF variables ΔF and ΔQ measure fluorescence.ResultsA strong correlation was identified between lesion depth and ΔF (r = ?0.765, p < 0.0001), and ΔQ (r = ?0.827, p < 0.0001) on intact lesions while a weak but suggestive, although non-significant, correlation was identified between average lesion depth and ΔR (r = 0.369, p = 0.059) and ΔX (r = 0.595, p = 0.0011). However, the corresponding correlation was not statistically significant, when lesions with surface loss were considered for QLF and MDP measures.ConclusionsQLF measures ΔF and ΔQ were strongly correlated with lesion depth in lab-simulated lesions with no surface loss, but not among lesions with surface defects. The two MDP-associated measures, ΔR and ΔX, could not be said to differ significantly when lesions with and without surface defects were compared with lesion depth. Because intact lesions can be remineralized, accurate assessment of their status is imperative for caries treatment.Clinical significanceDental caries is still widely prevalent today. We now know that with early stage detection, remineralization can be accomplished. Being able to identify dental caries in its reversible stage (before physical surface loss) is paramount for the clinician to be able to treat the disease non-invasively.     

Nano-calcium phosphate and dimethylaminohexadecyl methacrylate adhesive for dentin remineralization in a biofilm-challenged environment

ObjectiveDentin remineralization at the bonded interface would protect it from external risk factors, therefore, would enhance the longevity of restoration and combat secondary caries. Dental biofilm, as one of the critical biological factors in caries formation, should not be neglected in the assessment of caries preventive agents. In this work, the remineralization effectiveness of demineralized human dentin in a multi-species dental biofilm environment via an adhesive containing nanoparticles of amorphous calcium phosphate (NACP) and dimethylaminohexadecyl methacrylate (DMAHDM) was investigated.MethodsDentin demineralization was promoted by subjecting samples to a three-species acidic biofilm containing Streptococcus mutans, Streptococcus sanguinis, Streptococcus gordonii for 24 h. Samples were divided into a control group, a DMAHDM adhesive group, an NACP group, and an NACP + DMAHDM adhesive group. A bonded model containing a control-bonded group, a DMAHDM-bonded group, an NACP-bonded group, and an NACP + DMAHDM-bonded group was also included in this study. All samples were subjected to a remineralization protocol consisting of 4-h exposure per 24-h period in brain heart infusion broth plus 1% sucrose (BHIS) followed by immersion in artificial saliva for the remaining period. The pH of BHIS after 4-h immersion was measured every other day. After 14 days, the biofilm was assessed for colony-forming unit (CFU) count, lactic acid production, live/dead staining, and calcium and phosphate content. The mineral changes in the demineralized dentin samples were analyzed by transverse microradiography.ResultsThe in vitro experiment results showed that the NACP + DMAHDM adhesive effectively achieved acid neutralization, decreased biofilm colony-forming unit (CFU) count, decreased biofilm lactic acid production, and increased biofilm calcium and phosphate content. The NACP + DMAHDM adhesive group had higher remineralization value than the NACP or DMAHDM alone adhesive group.SignificanceThe NACP + DMAHDM adhesive was effective in remineralizing dentin lesion in a biofilm model. It is promising to use NACP + DMAHDM adhesive to protect bonded interface, inhibit secondary caries, and prolong the longevity of restoration.