Marina Sousa Azevedo

An in vitro biofilm model for enamel demineralization and antimicrobial dose-response studies.

Microcosm biofilms formed in microplates have demonstrated complex community dynamics similar to natural dental biofilm. No simplified microcosm models to evaluate enamel demineralization and dose-response effect to anticariogenic therapies have yet been established, thus this study was designed to develop a pre-clinical model fulfilling this purpose. Experiments were carried out to establish the time of biofilm formation and the sucrose concentration and exposure regimen. Biofilms were initiated from saliva and grown for up to 10 days on bovine enamel discs in 24-well plates, with a saliva analogue medium. Data were collected as pH readings and thepercentage enamel surface hardness change. A dose-response evaluation was performed with chlorhexidine, which significantly affected the pH and mineral loss. Overall, the established model parameters, 5 days of biofilm growth with intermittent 1% sucrose exposure of 6 h per day, was suitable as a pre-clinical model for enamel demineralization and dose-response studies.

Microcosm Biofilms Originating from Children with Different Caries Experience Have Similar Cariogenicity under Successive Sucrose Challenges

Objectives: The source of saliva inocula and the individual characteristics of saliva donors could affect the cariogenic activity of in vitro biofilms, but this could also be modulated by environmental determinants, such as the frequency of sugar consumption. Therefore, the aim of this study was to compare the cariogenicity of microcosm biofilm growths from the saliva of caries-free (CF) children, children with early childhood caries (ECC) and with severe ECC (S-ECC), under regular sucrose exposure. Methods: Microcosm plaque biofilms were initiated from the saliva of CF, ECC and S-ECC children. Biofilms were grown in 24-well microplates on bovine enamel discs for up to 10 days in artificial saliva, which was replaced daily. Growth conditions comprised cariogenic challenge (artificial saliva supplemented with 1% sucrose 6 h/day) or no cariogenic challenge. Daily pH was obtained from the artificial saliva, and after the experimental period, the biofilm formed on the enamel discs was collected for microbiological analyses. Mineral loss in enamel discs was estimated by percentage of surface hardness change. Results: Overall, no statistically significant differences were found among saliva sources (p > 0.05). Streptococcus mutans and lactobacilli counts increased in the biofilms grown under cariogenic challenge (p < 0.05), while a substantial decrease in the artificial saliva pH was detected under the same condition (p < 0.001). Higher demineralization (p < 0.001) was observed under sucrose exposure regardless of caries experience of children. Conclusions: While the sucrose exposure determined the cariogenicity of the biofilms, the caries experience of children who provided the inocula did not affect mineral loss associated with these biofilms.

Effect of Yogurt Containing Bifidobacteriumanimalis subsp. lactis DN-173010 Probiotic on Dental Plaque and Saliva in Orthodontic Patients

Aim: To assess how consumption of yogurt containing Bifidobacteriumanimalis subsp. lactis DN-173010 probiotic for a period of 2 weeks affects salivary and dental plaque levels of mutans streptococci and lactobacilli in patients undergoing orthodontic treatment. Methods: A crossover, double-blind, randomized and placebo-controlled clinical trial was performed with 26 volunteers. The study was divided into four periods. During periods 2 and 4, the volunteers ingested yogurt containing probiotic or control yogurt daily for 2 weeks. Periods 1 and 3 were a 1-week run-in period and 4-week washout period, respectively. Saliva and dental plaque samples were collected from each participant at the end of each period. Mutans streptococci, lactobacilli, and total cultivable microorganisms were counted. Values were compared between groups and across periods with the Wilcoxons test. Results: There was no difference between the yogurt containing probiotic and the control yogurt for any of the studied variables (all p > 0.05). A reduction in counts of total cultivable microorganisms was observed in dental plaque samples after ingestion of either yogurts (both p < 0.05 vs. baseline), but not in saliva (p < 0.05). Conclusion: Daily ingestion of yogurt with or without B. animalis subsp. lactis for a period of 2 weeks was beneficial in reducing total microbial counts in dental plaque. Therefore, no additional benefits were achieved by the use of the tested probiotic strain.

Where and how are Brazilian dental students using Glass lonomer Cement

Glass Ionomer Cements (GICs) have a wide range of uses in Dentistry, and the manipulation technique used can influence the results obtained. This study aimed at assessing the knowledge held by Dental School students from a city in Southern Brazil regarding the use of GIC, and the clinical technique chosen for its use and its applications. A structured questionnaire was applied to 60 advanced dental students. Descriptive statistics was used to analyze the quantitative data. All students had already used the material. Regarding the purpose for which the material was used, all students (100%) had used it as a dental cavity liner, 83.3% had used it as a temporary restorative material after endodontic treatment, and 73.3% had used it as a permanent restoration in primary teeth. Regarding the clinical technique used, 86.7% said that they insert the material while it still has a shiny surface, 33% said that they finish and polish the restoration in a following session, and only 28.3% said that they apply a surface protection immediately after the restoration is placed. Although students generally seem to be acquainted with the fundamental knowledge and main techniques involved in GIC use, they occasionally fail to follow all the technical steps required during clinical application, which may affect treatment outcome. Therefore, professors should stress that all the clinical procedures required during GIC application must be followed strictly to improve the performance of this material.

Efficacy of 1.23% APF gel applications on incipient carious lesions: a double-blind randomized clinical trial

The aim of this double-blind randomized clinical trial was to evaluate the efficacy of 1.23% APF gel application on the arrest of active incipient carious lesions in children. Sixty 7- to 12-year-old children, with active incipient lesions were included in the study. Children were divided randomly into 2 groups: 1.23% APF gel and placebo gel applications. Each group received 8 weekly applications of treatment. The lesions were re-evaluated at the 4th and 8th appointments. Poisson regression analysis was used to estimate relative risks of the presence of active white spot lesions. Groups showed similar results (PR = 1.67; CI 95% 0.69-3.98). The persistence of at least 1 active lesion was associated with a higher number of lesions in the baseline (PR = 2.67; CI 95% 1.19-6.03), but not with sugar intake (PR = 1.06; CI 95% 0.56-2.86) and previous exposure to fluoride dentifrice (PR = 1.26; CI 95% 0.49-2.29). The trial demonstrates the equivalence of the treatments. The use of the APF gel showed no additional benefits in this sample of children exposed to fluoridated water and dentifrice. The professional dental plaque removal in both groups may also account for the resulting equivalence of the treatments.

Correlation between the cariogenic response in biofilms generated from saliva of mother/child pairs.

This study aimed to correlate the cariogenic responsiveness of biofilms generated from the saliva of mothers and children. The mother–child pairs were classified according to the children’s caries levels: caries-free, early childhood caries (ECC) or severe ECC. Microcosm biofilms were grown on enamel discs for 10 days. Factors under evaluation were caries experience levels, inoculum source (mothers and children) and growth conditions including cariogenic challenge (growth medium provided with and without sucrose) and no cariogenic challenge (growth medium sucrose-free). Statistical analysis was performed with ANOVA and Tukey’s test, and the Spearman correlation test. Regular sucrose exposure resulted in a higher surface hardness change (%SHC). The correlation between biofilms formed from saliva of mother–child pairs was significant regarding pH, total aciduric microorganisms and lactobacilli counts under cariogenic challenge. Biofilm growth originating from mother–child pairs under regular sucrose exposure promoted the same cariogenic response independently of caries experience and the microbiological profile of the donors.

Super)hydrophobic coating of orthodontic dental devices and reduction of early oral biofilm retention

This study was designed to apply (super)hydrophobic crosslinked coatings by means of a sol-gel process on the surface of orthodontic devices and investigate the potential effect of these coatings in reducing the early retention of oral biofilm. Two organosilane-based hydrophobic solutions (HSs) were prepared containing hexadecyltrimethoxysilane diluted in ethanol (HS1) or 1H, 1H, 2H, 2H-perfluorodecyltriethoxysilane diluted in dimethyl sulfoxide (HS2). Stainless steel plates and ceramic discs were coated with HS1 or HS2 and heated at 150 °C for 2 h for condensation of a crosslinked SiO x network. Organosilane coatings were applied after previous, or no, surface sandblasting. Commercial stainless steel and ceramic brackets were used to evaluate oral biofilm retention after 12 h or 24 h of biofilm growth, using a microcosm model with human saliva as the inoculum. Surface roughness analysis (Ra, μm) indicated that sandblasting associated with organosilane coatings increased roughness for stainless steel brackets only. Analysis of the water contact angle showed that the stainless steel surface treated with HS1 was hydrophobic (~123°), while the ceramic surface treated with HS2 was superhydrophobic (~155°). Biofilm retention after 24 h was significantly lower in groups treated with hydrophobic coatings. An exponential reduction in biofilm accumulation was associated with increased water contact angle for both stainless steel and ceramic at 24 h. Application of (super)hydrophobic coatings on the surface of stainless steel and ceramic orthodontic devices might reduce the retention of oral biofilm.

Evaluation of a feasible educational intervention in preventing early childhood caries

Early childhood caries (ECC) in the primary dentition of preschoolers remains high. Young children have limited access to oral healthcare, and oral health education (OHE) measures can be a valuable tool to prevent caries in this population. The aim of this study was to evaluate the impact of an early educational intervention on ECC prevention. The study group (SG) comprised 271 children aged 0-12 months and their mothers, who attended 12 selected public health centers (PHC). The SG received oral health instructions from a pamphlet and by verbal explanation of some topics. One year later, a similar sample of children from another 12 PHCs were selected to serve as the control (CG; n = 251). The children were examined to determine their caries status: decayed = cavitated and/or white spot lesion (maxillary anterior surface); missing; and filled surface index > 0. There was a one-year follow-up. Socioeconomic and demographic information was collected. Logistic regression was used to estimate the effects of the educational intervention on the ECC odds. A sample of 445 (SG = 194 and CG = 251) children remained to the end of the study and were examined. The prevalence of caries was 12.9% in the SG and 17.9% in the CG. The odds of caries were 80% higher in the CG than in the SG (p = 0.037). The strategy of providing OHE from a pamphlet and with a brief verbal instruction to mothers during their childs first year of life can constitute a valuable tool for ECC prevention.

Maternal Depression Increases Childhood Dental Caries: A Cohort Study in Brazil

Aim: To investigate the relationship between maternal depression and childhood caries in a cohort of adolescent mothers. Methods: This cross-sectional study nested in a cohort evaluated a sample of 538 mother/child dyads. When the children were 24-36 months of age, data regarding oral health from children and mothers were collected by clinical dental examination. A mothers major depressive disorder was assessed by using the Mini International Neuropsychiatric Interview (MINI [Plus]), at the current moment. Independent variables were obtained by using questionnaires. The outcome on dental caries experience was dichotomized by using 2 cut points: dmfs ≥1 and dmfs ≥3. Poisson regression analysis, using a hierarchical approach, was applied to assess the association between major depressive disorder in mothers with and those without caries experience and the outcome. Results: The prevalence of dental caries in children was 15.1% (n = 82). The mean dmfs index was 1.12 (SD = 3.72). The prevalence of major depressive disorder was 32.6% (n = 168). An interaction between caries status and depressive disorder was found, and after adjusted analysis, children from mothers with major depressive disorder with negative caries experience presented a higher caries prevalence (prevalence ratio 4.00, 95% confidence interval 1.29-12.41). Conclusion: Our findings suggest that maternal psychiatric disorders could have a negative impact on childrens oral health.

Oral health-related quality of life in Brazilian child abuse victims: A comparative study

This study aims to assess and compare Oral Health-Related Quality of Life (OHRQoL) in child abuse victims and non-abused children in a Southern Brazilian city. The study compared two independent samples of children aged 8-10 years: 48 child abuse victims recruited from a centre for Child and Adolescent Psychological Support (NACA) for abused children, and 144 public and private school students. Data collection consisted of administration of the Child Perceptions Questionnaire 8-10 (CPQ8-10) to measure OHRQoL (dependent variable), clinical examination (dental caries), and collection of socioeconomic and demographic information (age, sex, skin colour, family income, and type of school). Multiple linear regression models were used to assess the association between presence of abuse and OHRQoL and subscales. After adjustment for clinical and sociodemographic variables, child abuse victims were found to exhibit higher CPQ scores on the overall scale and on the oral symptoms and functional limitations subscales. In conclusion, child abuse victims have a higher impact on OHRQoL. Based on the results, it is possible to suggest that greater care should be taken of these children, not only in providing treatment for oral disorders, but also in providing interdisciplinary care.