Presence of Streptococcus mutans or Streptococcus sobrinus in Cariostat®-inoculated plaque samples from Japanese mother-child pairs

The aim of this study was to determine the presence of Streptococcus mutans or Streptococcus sobrinus in Cariostat-inoculated plaque samples obtained from Japanese mother-child pairs through a conventional PCR technique and to establish the presence of these bacteria and caries risk. Oral examination and caries risk assessment using the Cariostat^® were carried out on 168 children, aged 6–31 months, and their mothers. The presence of S. mutans and S. sobrinus in Cariostat-inoculated plaque samples was checked through PCR and tested for relevance with caries risk. A significant correlation (P < 0.001) was found between caries risk of mothers and presence of S. mutans or S. sobrinus in plaque samples from their children in the 19–31-month-old age range. However, no significant relationship found between the presence of either strain in the plaque of younger children (6–18 months) and caries risk of mothers. Likewise, high caries risk was seen in 49.1% of the 19–31-month-old children of highrisk mothers (P < 0.001) and 27% of the 6–18-month-old children of high-risk mothers (P < 0.05). The effectiveness of the Cariostat method for prediction of caries risk can be improved by detecting the presence of S. mutans and S. sobrinus in plaque samples obtained from mothers and their children through conventional PCR techniques.     

Detection of mutans streptococci in plaque samples from Mongolian preschool and school children

Mutans streptococci, in particular Streptococcus mutans and Streptococcus sobrinus, are generally considered to be the principal microbial pathogen of dental caries. The objective of the study was to isolate S. mutans and S. sobrinus, identify them by PCR, and to compare their presence with the caries status and caries risk in Mongolian preschool and school children. Forty one preschool children aged 3–5 years and 40 school children aged 12–15 years were enrolled in this study. As assessed using Cariostat test, 75.6% of preschool children had high caries risk and 37.5% of school children had high caries risk. In preschool children, the prevalence of S. mutans and S. sobrinus were 100% and 36.6%, respectively; 63.4% were positive for S. mutans alone and 36.6% were positive for both S. mutans and S. sobrinus. In school children, the prevalence of S. mutans and S. sobrinus were 100% and 25.0%, respectively; 75.0% carried S. mutans alone and 25.0% had both S. mutans and S. sobrinus. The percentage of children positive for both S. mutans and S. sobrinus in the high caries risk group were significantly higher than those in the low risk group of either preschool (42.0% vs. 10.0%, P< 0.001) or school children (46.6% vs. 12.0%, P<0.001). Moreover, the caries status of children positive for both S. mutans and S. sobrinus were significantly higher than those positive for S. mutans alone (P< 0.01 for preschool children, and P< 0.05 for school children).     

Risk behaviors and its association with caries activity and dental caries in Japanese children

The aim of this study was to assess risk behaviors and its association with caries activity and dental caries in Japanese children. The subjects were 392 young Japanese children who underwent dental health check-up at 18, 30 and 42 months of age. Oral examinations, Cariostat tests and dental health questionnaires were carried out at each time. The caries prevalence of children was 1.5% at 18 months, 9.9% at 30 months and 28.1% at 42 months. Caries activity based on the Cariostat scores of children was correlated with caries status (caries-free/carious) at 42 months. In children with caries during each examination period at 42 months, eating snacks while playing was ranked as the most important behavioral risk (P < 0.001), followed by breast-feeding (P < 0.01), non setting of time for snacks (P < 0.05) and frequency of snacks (P < 0.05) at 18 months old; non brushing by mother (P < 0.05) and eating snacks while playing (P < 0.05) were ranked highest at 30 months old. In addition, eating snacks while playing (P < 0.001) at 42 months old was the only a significant factor for children with caries. Caries activity and risk behaviors were associated with caries experience at different age periods of childhood.     

PCR detection of Streptococcus mutans and Streptococcus sobrinus in plaque samples from Mongolian mother-child pairs

Early childhood caries results in a considerable burden of pain and suffering as well as poorer general health. Streptococcus mutans (serotypes c, e and f ) and Streptococcus sobrinus (serotype d and g) are the species closely associated with dental caries. The exact age at which their colonization occurs in children is controversial. The objective of this study was to detect S. mutans and S. sobrinus in plaque samples of Mongolian mother-child pairs by PCR and to compare their presence with the caries status. Dental examination and caries risk assessment using the Cariostat^® carried out on 320 children aged 6–30 months and their mothers. The presence of S. mutans and S. sobrinus was checked by PCR. The caries prevalence and DEFT scores of mothers enrolled in the present study were 98% and 11.5±0.7, respectively. In children, the prevalence and deft scores of the 6–18-month-olds were 29% and 1.3±0.2 while those of the 19–30-month-olds were 59% and 3.4±0.4 correspondingly. Twenty nine percent of the 6–18-months old children of high-risk mothers and 53.1% of the 19–30-months old children of high-risk mothers had high caries risk (P<0.001). There was a statistically significant correlation between caries risk of 19–30 month-old children and their mothers (P<0.001). In mothers, the prevalence of S. mutans and S. sobrinus was 79% and 33%, respectively; 54% harbored S. mutans alone, 8% harbored S. sobrinus alone, 25% harbored both strains. In children, 45% were positive for S. mutans alone, 9% were positive for S. sobrinus alone, 18% were positive for both strains. Either or both strains were detected in 67.3% of 6–18-months old children and 76.5% of 19–30-months old children. In conclusion, our results showed that S. mutans and/or S. sobrinus first colonized infants’ teeth from 6–18 months, and the colonization increased with increasing age, so that by 30 months of age, 76.5% of children harbored the bacteria.     

Quantitative assessment of salivary oral bacteria according to the severity of dental caries in childhood

This study aimed to assess differences in selected oral bacteria in children according to the severity of dental caries. One hundred and thirty-six children, 36–60 months old were divided into three groups according to caries status: caries-free (CF) (n = 47), early childhood caries (ECC) (n = 40) and severe-early childhood caries (S-ECC) (n = 49). Saliva was collected for detection and quantification of selected oral streptococci, Actinomyces naeslundii, Lactobacillus spp., Bifidobacterium spp., and Scardovia wiggsiae by quantitative-polymerase chain reaction. The results showed that the detection and quantitative levels of S. mutans, S. sobrinus, Bifidobacterium spp. and S. wiggsiae were significantly higher in S-ECC children compared to CF and ECC children, while for S. salivarius were significantly higher in CF compared to ECC and S-ECC children. There was no statistical difference among the clinical groups for S. mitis, S. oralis, A. naeslundii and Lactobacillus spp. levels and detection. S-ECC children had a lower monthly family income, started tooth brushing later and were breastfeed for a longer duration compared to CF children. S. mutans levels were positively correlated with S. wiggsiae and Bifidobacterium spp. levels, lower mother’s education and child bottle-feeding before sleeping and negatively correlated with S. salivarius. It was concluded that in addition to S. mutans, other bacterial species, including bifidobacteria, Scardovia wiggsiae and S. sobrinus, are associated with severity of early childhood caries, although their role in the progress of dental caries remains unclear.     

Influence of sucrose and xylitol on an early Streptococcus mutans biofilm in a dental simulator

ObjectivesIn vitro methods to study dental biofilms are useful in finding ways to support a healthy microbial balance in the oral cavity. The effects of sucrose, xylitol, and their combination on three strains of Streptococcus mutans and one strain of Streptococcus sobrinus were studied using a dental simulator.MethodsA simulator was used to mimic the oral cavity environment. It provided a continuous-flow system using artificial saliva (AS), constant temperature, mixing, and hydroxyapatite (HA) surface in which the influence of xylitol was studied. The quantities of planktonic and adhered bacteria were measured by real-time qPCR.ResultsCompared against the untreated AS, adding 1% sucrose increased the bacterial colonization of HA (p < 0.0001) whereas 2% xylitol decreased it (p < 0.05), with the exception of clinical S. mutans isolate 117. The combination of xylitol and sucrose decreased the bacterial quantities within the AS and the colonization on the HA by clinical S. mutans isolate 2366 was reduced (p < 0.05). Increasing the concentration (2%–5%) of xylitol caused a reduction in bacterial counts even in the presence of sucrose.ConclusionsThe continuous-culture biofilm model showed that within a young biofilm, sucrose significantly promotes whereas xylitol reduces bacterial colonization and proliferation. The results indicate that xylitol affects the ability of certain S. mutans strains to adhere to the HA. Clinical studies have also shown that xylitol consumption decreases caries incidence and reduces the amount of plaque. This study contributes to the understanding of the mechanism behind these clinical observations.     

Effects of S. mutans gene-modification and antibacterial monomer dimethylaminohexadecyl methacrylate on biofilm growth and acid production

ObjectivesAntibacterial quaternary ammonium monomers (QAMs) are used in resins. The rnc gene in Streptococcus mutans (S. mutans) plays a key role in resisting antibiotics. The objectives of this study were to investigate for the first time: (1) the effects of rnc deletion on S. mutans biofilms and acid production; (2) the combined effects of rnc deletion with dimethylaminohexadecyl methacrylate (DMAHDM) on biofilm-inhibition efficacy.MethodsParent S. mutans strain UA159 (ATCC 700610) and the rnc-deleted S. mutans were used. Bacterial growth, minimum inhibitory concentration (MIC), and minimal bactericidal concentration (MBC) were measured to analyze the bacterial susceptibility of the parent and rnc-deleted S. mutans against DMAHDM, with the gold-standard chlorhexidine (CHX) as control. Biofilm biomass, polysaccharide and lactic acid production were measured.ResultsThe drug-susceptibility of the rnc-deleted S. mutans to DMAHDM or CHX was 2-fold higher than parent S. mutans. The drug-susceptibility did not increase after 10 passages (p < 0.05). Deleting the rnc gene increased the biofilm susceptibility to DMAHDM or CHX by 2-fold. The rnc-deletion in S. mutans reduced biofilm biomass, polysaccharide and lactic acid production, even at no drugs. DMAHDM was nearly 40 % more potent than the gold-standard CHX. The combination of rnc deletion + DMAHDM treatment achieved the greatest reduction in biofilm biomass, polysaccharide synthesis, and lactic acid production.SignificanceGene modification by deleting the rnc in S. mutans reduced the biofilm growth and acid production, and the rnc deletion + DMAHDM method showed the greatest biofilm-inhibition efficacy, for the first time. The dual strategy of antibacterial monomer + bacterial gene modification shows great potential to control biofilms and inhibit caries.     

Effect of arginine on the growth and biofilm formation of oral bacteria

BackgroundAlkali production via arginine deiminase system (ADS) of oral bacteria plays a significant role in oral ecology, pH homeostasis and inhibition of dental caries. ADS activity in dental plaque varies greatly between individuals, which may profoundly affect their susceptibility to caries.ObjectiveTo investigate the effect of arginine on the growth and biofilm formation of oral bacteria.Methods and resultsPolymicrobial dental biofilms derived from saliva were formed in a high-throughput active attachment biofilm model and l-arginine (Arg) was shown to reduce the colony forming units (CFU) counts of such biofilms grown for various periods or biofilms derived from saliva of subjects with different caries status. Arg hardly disturbed bacterial growth of Streptococcus mutans, Streptococcus sobrinus, Streptococcus sanguinis and Streptococcus gordonii in BHI medium, but only inhibited biofilm formation of S. mutans. Scanning electron microscope (SEM) showed S. mutans biofilms harboured fewer cells grown with Arg than that without Arg, even in the initial 2 h and 8 h phase. Confocal laser scanning microscope (CLSM) images of poly-microbial dental and S. mutans biofilms revealed the biofilms grown with Arg had lower exopolysaccharide (EPS)/bacteria ratios than those without Arg (P = 0.004, 0.002, respectively). Arg could significantly reduce the production of water-insoluble EPS in S. mutans biofilms (P < 0.001); however, quantitative real-time PCR (qRT-PCR) did not show significantly influence in gene expression of gtfB, gtfC or gtfD (P = 0.32, 0.06, 0.44 respectively).ConclusionsArg could reduce the biomass of poly-microbial dental biofilms and S. mutans biofilms, which may be due to the impact of Arg on water-insoluble EPS. Considering the contribution to pH homeostasis in dental biofilms, Arg may serve as an important agent keeping oral biofilms healthy thus prevent dental caries.     

Relationship between caries risk and presence of cariogenic bacteria among Japanese pregnant women

ObjectivesTo analyze the relationship between caries risk and the presence of S. mutans and S. sobrinus from plaques of pregnant women using the Cariostat method and the polymerase chain reaction (PCR) technique.Materials and MethodsThe subjects consisted of 269 pregnant women who were in their 3rd, 4th or 5th month of pregnancy. The presence of S. mutans and S. sobrinus was assessed from their plaques cultured in the Cariostat medium and assessed by PCR.ResultsThe correlation between caries risk scores assessed by the Cariostat method and the presence of S. mutans was statistically significant (P<0.05). The tendency of positive correlation was found between the presence of S. sobrinus and caries activity.ConclusionThis study suggested that pregnant women who have high caries activity should be more aware of the possibility of transmission of cariogenic bacteria to their infants.     

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.     

Associations between caries activity,salivary buffer tests and caries increment in Mongolian children

The aim of the study was to evaluate caries increment in combination with a caries activity test (CAT21 Test) and a salivary buffer test (CAT21 Buf Test)—to predict future caries activity in Mongolian preschool children living in Ulaanbaatar City. The effectiveness of combining both tests and deft (decayed, extracted, filled teeth) means was also investigated. The caries prevalence in subjects was 94%, and deft mean value was 6.8. The caries increment after one year was 2.3 teeth. From the distribution of CAT21 Test scores a low risk was found in 38.6% and high risk in 61.4% of the examined children. From the CAT21 Buf Test scores, the high risk (lower buffer capacity) was found in 79.8% of the examined children. When the combination CAT21 Test and CAT21 Buf Test scores were divided into four groups (low-low/lowhigh/ high-low/high-high), the mean def-teeth showed a significant difference among the four groups (ANOVA P < 0.001). One year after the caries increment was evaluated in combination with the CAT21 Test scores and CAT21 Buf Test scores, the low-low risk group showed the lowest mean def-teeth. On the other hand, the high-high risk group showed the highest mean def-tooth (ANOVA P < 0.05). Based on these results, the CAT21 Test and CAT21 Buf Test are useful for clinical application of preschool children in predicting future caries activity. Furthermore, when the CAT21 Test and the CAT21 Buf Test were combined, a higher correlation was shown with the caries status.     

Microbial screening of Cariostat®-inoculated plaque samples from low and high caries risk children

The aim of the present study was to investigate caries activity and it's association with the presence of S. mutans and S. sobrinus. The subjects were 499 children aged 2.5 years old, who participated in dental health examinations held from May 2006 to January 2007 at a health center in Katano City, Osaka, Japan. A dental examination was performed based on caries diagnostic criteria of the Health Policy Bureau, Ministry of Welfare, Japan. Plaque samples were collected using a sterile cotton swab from the maxillary buccocervical surfaces by the same dental hygienist. Two hundred seventy two (54.5%) children who had Cariostat score below 1.5 were determined as low risk and 227 (45.5%) who had a score above 2.0 as high risk. For microbial screening, 100 children were randomly selected from the high and low risk groups. The presence of S. mutans and S. sobrinus were detected using PCR technique. Thirty seven (18.5%) children had S. mutans alone, 20 (10.0%) had S. sobrinus alone, 16 (8.0%) had both S. mutans and S. sobrinus, and 127 (63.5%) had neither S. mutans nor S. sobrinus. Cariogenic bacteria were detected more from high caries risk than low caries risk children. A larger number of S. sobrinus was found in children with high df numbers than low df numbers. In this study, it was shown that S. sobrinus was more closely related with high caries risk activity and high df numbers.     

Relationship of quantitative salivary levels of Streptococcus mutans and S. sobrinus in mothers to caries status and colonization of mutans streptococci in plaque in their 2.5-year-old children

Abstract – Objectives: The aim of this study was to assess the relationships of quantitative salivary levels of Streptococcus mutans and S. sobrinus in mothers with the colonization of mutans streptococci (MS) in plaque and caries status in their 2.5‐year‐old children. Furthermore, the dynamics of caries status in the children was evaluated in a 2‐year follow‐up survey. Methods: After oral examination of 54 mother‐and‐child pairs, the saliva samples from the mothers and the plaque samples from the children were collected. The levels (log DNA copies/ml saliva) of S. mutans and S. sobrinus were quantified using real‐time polymerase chain reaction (PCR) assays, while MS in the plaque samples were detected using a cultivation method. In addition, 50 of the 54 children participated in a 2‐year follow‐up survey of caries prevalence. Results: In the 2.5‐year‐old children, the percentage of dft‐positive subjects and mean number of dft were significantly higher in the MS(+) group when compared with the MS(?) group. Findings from the 2‐year follow‐up survey indicated that MS(+) subjects had a persistently higher mean number of dft at 4.5 years. The 2.5‐year‐old children were divided into three groups based on the quantitative levels of salivary S. mutans and S. sobrinus in their mothers: those whose mothers had low levels of S. mutans (<4 log DNA copies/ml) and S. sobrinus (<2) (group 1); those whose mothers had a high level of S. mutans (≥4) and low level of S. sobrinus (<2) (group 2); and those whose mothers had high levels of both (≥4 and ≥2, respectively) (group 3). Among the three groups, the percentages of MS(+) and dft‐positive children were highest in group 3 and lowest in group 1. Furthermore, multiple logistic regression analyses revealed that grouping the mothers based on salivary level of S. mutans and S. sobrinus was an efficient means to predict both MS colonization (OR = 2.96) and prevalence of dental caries (OR = 9.39) in children at 2.5 years of age. Conlusions: In the 54 mother‐and‐child pairs tested, the maternal salivary levels of S. mutans and S. sobrinus determined by real‐time PCR were significantly related to MS colonization in plaque as well as dental caries in their children at 2.5 years of age. Thus, determination of maternal levels of both organisms using the present cut‐off values is proposed as an efficient method to indicate the risks of maternal transmission of MS and childhood dental caries.     

Effect of bovine lactoferrin on enamel demineralization and acid fermentation by Streptococcus mutans

The purpose of this study was to evaluate the effects of bovine lactoferrin on acid fermentation and enamel demineralization using Streptococcus mutans in a culture system and an artificial mouth model system. The antibacterial activity of bovine lactoferrin (bLF) against S. mutans was analyzed by a radial diffusion assay. In the culture system, the effect of bLF on the synthesis and adherence of water insoluble glucan (WIG) and the adherence of S. mutans to a glass surface was examined by a batch culture. In the artificial mouth model system, cell suspension of S. mutans, heart infusion broth supplemented with sucrose, and PBS or lactoferrin solution were supplied separately and constantly for 21 hours. The following parameters were determined for evaluation: the amount of artificial biofilm, the changes in pH underneath the biofilm; and the changes in enamel microhardness measured by a Vicker's hardness tester. The antibacterial activity of bLF against S. mutans was observed. The amounts of bacterial cells in the total adherent fractions were inhibited by bLF in a dose dependent manner. The amounts of WIG in a firm-adherent fraction were significantly inhibited by 0.1–1.0% bLF. The changes in microhardness on enamel slabs in the bLF group (2.4 ± 0.8) showed significantly less hardness reduction than those in the control group (22.3 ± 2.5) (P < 0.001). The artificial biofilm accumulation was not reduced by bLF. The results of this study suggest that bLF might have inhibitory effects against acid fermentation and demineralization of enamel by S. mutans.     

Identification of appropriate outcome indices in head and neck cancer and factors influencing them

Audit of early postoperative outcomes adjusted for patient case mix is still in its infancy in head and neck surgery. Nevertheless the role for audit of early postoperative outcomes is obvious. The primary outcome measure of this study was to identify factors that are associated with early mortality or morbidity after surgery for head and neck squamous cell carcinoma (HNSCC). The secondary outcome measure was to develop a pilot score that allows for risk-adjustment of outcome data to facilitate departmental audit. In this series the mortality rate was low (2.8%), in keeping with other published series. Complications, including those causing death, occurred after 38.1% of operations. Independent risk factors for mortality on logistic regression were shown to be previous HNSCC (P = 0.03), estimated blood loss (l) (P = 0.03), and extracapsular spread (P = 0.05). Age (P = 0.01), tracheostomy (P < 0.01), estimated blood loss (l) (P = 0.05), and duration of anaesthesia (P < 0.01) were independent predictors of complications. Models predicting for risk demonstrated good discrimination (area under the curve statistics) for mortality (0.86) and morbidity (0.81). These pilot scores need external validation and may herald a means of facilitating risk-adjustment in the audit of early outcomes, allowing meaningful comparison of surgeons and their units over time.     

Evaluation of effects of activator treatment on mandibular growth by analyzing components of condylar growth and mandibular rotation

PurposeThe objective of this study is to clarify the effects of activator treatment on mandibular growth in relation to condylar growth and total rotation of the mandible, and to investigate the relationships between the treatment responses and pretreatment facial morphology.Materials and methodsThirty Japanese girls with Class II division 1 malocclusion treated with activator were examined. Mean age at the start of treatment was 9.6 ± 1.6 years. Mean treatment duration was 19 ± 4 months. Lateral cephalograms obtained before and after treatment were used to analyze skeletal changes during treatment. Regional superimposition analysis was performed to evaluate activator effects by decomposing the mandibular growth into condylar growth and mandibular total rotation.ResultsThe changes in intermaxillary relationships were significantly correlated with vertical condylar growth and mandibular total rotation (P < 0.05 and P < 0.01). The changes in the forward displacement of the mandible were significantly correlated with sagittal condylar growth and mandibular total rotation (P < 0.05 and P < 0.01). Vertical condylar growth and mandibular total rotation were significantly correlated with pretreatment mandibular morphology (P < 0.05 and P < 0.01).ConclusionBoth the sagittal condylar growth and counterclockwise mandibular total rotation attributed to activator treatment contribute to forward displacement of the mandible. The activator effects are expected greater in patients with flat mandibular plane, small gonial angle, backwardly inclined mandibular ramus and long posterior facial height.     

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.     

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.     

Effect of grape seed proanthocyanidins extract on alteration of mechanical properties of metaphysis tibia bone in rats fed a low-calcium diet

The effects of grape seed proanthocyanidins extract (GSPE, 3 mg in 100 g of high-calcium diet with a calcium content of 1697 mg/100 g) on rat metaphysis tibia formation following feeding of a low-calcium diet (30% of calcium in the standard diet) were investigated by examining bone density, mineral content, geometric and bone strength. Five-week old male Wistar rats (n = 40) were randomly divided into a control (Co) group, a low-calcium diet (LC) group, a low-calcium diet • high-calcium diet (LCH) group, and a lowcalcium diet • high-calcium diet with supplementary GSPE (LCHG) group. The metaphysis tibia bones were analyzed using three-dimensional peripheral quantitative computed tomography (pQCT), while whole tibia bones were tested for mechanical resistance using a material testing machine. We found no significant differences in body weight among the 4 groups. All bone parameters in the LC group were significantly lower than these in the Co group (P < 0.01). Furthermore, trabecular bone density (TrBD), trabecular bone mineral content (TrBMC), cross-sectional moment of inertia to the reference axis y (yCSMI), and stress-strain index to the reference axis x (xSSI) in the LCHG group were significantly higher than those in the LCH group (P < 0.05; P < 0.01; P < 0.05; P < 0.05, respectively), while stiffness in the LCHG and LCH groups were significantly higher than that in the LC group (P < 0.01). We concluded that a mixture of high-calcium and GSPE in the diet has a more beneficial effect on bone formation for the treatment of metaphysis tibia bone debility in rats than does a high-calcium diet alone.     

Effects of heat-inactivated Bifidobacterium BB12 on cariogenicity of Streptococcus mutans in vitro

ObjectiveSince some probiotic bacteria are cariogenic themselves, their suitability for caries management is questionable. Inactivated bacteria or their supernatants have been found to exert probiotic effects, whilst having several advantages compared with living bacteria. We hypothesized that viable and heat-inactivated Bifidobacterium animalis BB12 reduces the cariogenicity of Streptococcus mutans (SM) in vitro.DesignWe assessed mono- and mixed species biofilms of SM and viable or heat-inactivated BB12. Biofilms were grown in a continuous-culture-system under cariogenic conditions on smooth proximal enamel or cavitated dentine. For each of eight experimental subsets (4 biofilms × 2 hard-tissue conditions), a total of 32 specimens was used. After 10 days, bacterial numbers of 12 biofilms per group were analysed, and all specimens submitted to transversal microradiography.ResultsMineral loss was higher in cavitated dentine than smooth enamel for all biofilms (p < 0.001, t-test). BB12-monospecies biofilms induced significantly less mineral loss than SM in both enamel (p < 0.05) and dentine (p < 0.001). Viable BB12 did not significantly reduce cariogenicity of SM (p > 0.05), whilst heat-inactivated BB12 decreased cariogenicity of SM in dentinal cavities (p < 0.01). Bacterial numbers were higher on dentine than enamel (p < 0.05), but not significantly influenced by biofilm species (p > 0.05).ConclusionsHeat-inactivated BB12 reduced the cariogenicity of SM in dentinal cavities in vitro. Inactivated probiotics might be suitable for caries control.