Caries Prevention Effects of Silver Diamine Fluoride with 10,600 nm Carbon Dioxide Laser Irradiation on Dentin.

Objective: To investigate the caries prevention effect of silver diamine fluoride (SDF) with a carbon dioxide (CO2) laser (λ = 10,600 nm) on dentin. Method: Human dentin slices (n = 10) were prepared and allocated to the following treatments: Group 1 (SDF)-slices received an SDF application. Group 2 (laser)-slices were irradiated with a CO2 laser. Group 3 (laser + SDF)-slices were irradiated with a CO2 laser, followed by an SDF application. Group 4 (negative control)-slices had no treatment. All of the slices were subjected to pH cycling for cariogenic challenge. Lesion depth, nanohardness, and chemical and morphological changes were assessed by microcomputed tomography (micro-CT), nanoindentation, and scanning electron microscopy (SEM) with energy dispersive X-ray spectroscopy (EDS), respectively. Results: micro-CT determined lesion depths for groups 1-4 were 27 ± 6, 138 ± 32, 17 ± 5, and 182 ± 49 µm, respectively (p < 0.001; group 3 < group 1 < groups 2 and 4). The nanohardness values for groups 1-4 were 456 ± 109, 288 ± 5, 444 ± 142, and 258 ± 76 MPa, respectively (p = 0.003; groups 2 and 4 < groups 1 and 3). EDS determined that the calcium-to-phosphorus molar ratio for groups 1-4 were 1.26 ± 0.12, 1.07 ± 0.19, 1.37 ± 0.08, and 0.80 ± 0.17, respectively (p < 0.001; group 4 < group 2 < groups 1 and 3). SEM evidenced no ablation or cracking on the lased dentin surfaces. The treated dentin showed a relatively more intact and smoother surface morphology compared with the untreated dentin. Conclusions: SDF can reduce dentin demineralization against cariogenic challenge, and the caries preventive effect of SDF is further enhanced through CO2 laser irradiation.

Synthesis and Characterization of Fluoridated Silver Nanoparticles and Their Potential as a Non-Staining Anti-Caries Agent.

OBJECTIVES: The first objective of this study was to prepare sodium fluoride (NaF) solution with various concentrations of polyethylene glycol-coated silver nanoparticles (PEG-AgNPs). The second objective was to study the antibacterial activity against Streptococcus mutans and the tooth-staining effect of the solution. METHODS: PEG-AgNPs were prepared via the one-step chemical reduction of silver acetate with thiolated polyethylene glycol. The PEG-AgNPs were characterized with ultraviolet-visible spectrometry and transmission electron microscopy. The half maximal inhibitory concentration (IC50) for the PEG-AgNPs against Streptococcus mutans and human gingival fibroblasts (HGF-1) were determined. The staining effect on dentin and enamel for the 2.5% NaF solutions with PEG-AgNPs at 12,800, 6400, 1600, and 400 ppm was investigated using digital spectrophotometry. The IC50 of the fluoridated silver nanoparticles against Streptococcus mutans were measured. RESULTS: The PEG-AgNPs have an average diameter of 2.56±0.43 nm and showed excellent stability at high ionic strength (2.5% NaF) for 18 months. The IC50 of PEG-AgNPs against Streptococcus mutans was found to be 21.16±1.08 ppm silver, which was half of IC50 against HGF-1 cells (42.36±1.12 ppm), providing a working range to kill bacteria with no harm to human cells. The formulations with different concentrations of PEG-AgNPs showed no significant staining of teeth. Combining PEG-AgNPs with NaF significantly expanded the therapeutic window against Streptococcus mutans by reducing its IC50. CONCLUSION: A biocompatible solution of NaF with PEG-AgNPs was developed. Because it has antibacterial activity against Streptococcus mutans and no tooth-staining effect, it can be used as an anti-caries agent.

Dimethylaminododecyl methacrylate inhibits Candida albicans and oropharyngeal candidiasis in a pH-dependent manner.

The prevalence of stomatitis, especially that caused by Candida albicans, has highlighted the need for new antifungal agents. We previously found that a type of quaternary ammonium salts, dimethylaminododecyl methacrylate (DMADDM), incorporated in dental materials inhibited the growth and hyphal development of C. albicans. However, how the quaternary ammonium salts inhibited the fungal pathogens and whether the oral condition, such as salivary pH variation under different diseases, can affect the antimicrobial capacity of quaternary ammonium salts is unknown. This study evaluated the antifungal effects of DMADDM at different pH in vitro and in vivo. A pH-dependent antifungal effect of DMADDM was observed in planktonic and biofilm growth. DMADDM enhanced antifungal activity at alkaline pH. Two pH-regulated genes (PHR1/PHR2) of C. albicans were correlated with the pH-dependent antifungal effects of DMADDM. The PHR1/PHR2 genes and pH values regulated the zeta potential of C. albicans, which then influenced the binding between C. albicans cells and DMADDM. The pH-dependent antifungal activity of DMADDM was then substantiated in a murine oropharyngeal candidiasis model. We directly demonstrated that the antifungal abilities of quaternary ammonium salts relied on the cell zeta potential which affected the binding between fungal cells and quaternary ammonium salts. These findings suggest a new antifungal mechanism of quaternary ammonium under different pH and that DMADDM can be a potential antifungal agent applied in dental materials and stomatitis therapy.Key Points • DMADDM has stronger antifungal activity in alkaline than in acidic pH conditions. • The pH values and pH-regulated genes can affect the zeta potential of fungal cells. • Zeta potential of fungal cells directly affect the binding between DMADDM and cells. Graphical abstract Schematic diagram of the antifungal activities of DMADDM at different pH values.

Tooth wear among five-year-old children in Jakarta, Indonesia.

BACKGROUND: This study aimed to evaluate the prevalence of tooth wear among preschool children in Jakarta, Indonesia, and examine the risk factors associated with its occurrence. METHODS: An epidemiological survey was conducted with a cross-sectional study design. The participants were recruited via cluster sampling. Tooth wear was clinically assessed by one examiner using the Basic Erosive Wear Examination (BEWE) criteria. The children's caries experience was also recorded. The parents of the participating children completed a self-administered questionnaire to answer demographic questions about the children and gather information about the children's diet and oral health behaviors as well as the parents' dental health-related knowledge. The data were analyzed using the Chi-square test and binary logistic regression. RESULTS: A total of 752 five-year-old children were invited to participate, with 691 (92%) enrolling in the study. Tooth wear occurred in 23% (161/691, BEWE > 0) of the participants, in which 78% (125/161) had at least one moderate tooth wear status (BEWE = 2). The consumption of citrus drinks, fruit juice, and vitamin C supplement drinks, together with the child's caries experience, the father's education level, and the family's socioeconomic status, were significantly associated with tooth wear. CONCLUSIONS: The five-year-old preschool children in Jakarta had a relatively low prevalence of tooth wear. Those consuming more acidic drinks, those with a higher socioeconomic status, and those with an absence of caries experience had a higher risk of tooth wear.

Prevention of secondary caries using silver diamine fluoride treatment and casein phosphopeptide-amorphous calcium phosphate modified glass-ionomer cement.

OBJECTIVE: To study the effect of silver diamine fluoride (SDF) treatment and incorporating casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) into a glass-ionomer cement (GIC) to prevent secondary caries. METHOD: A cervical cavity was prepared on 32 premolars for the following restoration groups: group 1, conventional GIC restoration; group 2, SDF (38%) treatment and conventional GIC restoration; group 3, CPP-ACP (3%) modified GIC; and group 4, SDF treatment and CPP-ACP modified GIC. The restored teeth were thermal-cycled before undergoing a multi-species cariogenic biofilm challenge. The restored teeth were examined by micro-computed tomography (micro-CT), scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM/EDX) and Fourier transform infrared (FTIR) spectroscopy. Data were analyzed by two-way ANOVA. RESULTS: Micro-CT determined outer lesion depths for groups 1-4 were: 123±6µm, 87±7µm, 79±3µm and 68±5µm respectively. An interaction effect on the outer lesion depth was found between the restorative materials and SDF treatment (p<0.001). Both SDF treatment and modification with CPP-ACP had a significant effect on outer lesion depth (p<0.001). SEM/EDX showed an increase of calcium and phosphorus at the root dentine adjacent to the restoration in groups 3 and 4 (CPP-ACP modified GIC). FTIR revealed that SDF treatment and CPP-ACP modified GIC had a significant effect on amide I-to-hydrogen phosphate ratio on the material-root interface (p=0.001). CONCLUSION: SDF treatment and incorporation of CPP-ACP into GIC restorative material can prevent secondary root caries development. CLINICAL SIGNIFICANCE: The results provide useful information to dentists in formulating clinical management protocols and material when treating root caries.

Dental caries and erosion status of 12-year-old Hong Kong children.

BACKGROUND: This study aimed to assess the dental caries and erosion status of 12-year-old Hong Kong children and study the determinants of dental caries and dental erosion of these children. METHODS: The survey was performed from 2011 to 2012 with ethics approval. Stratified random sampling was adopted to select 12-year-old children in 7 primary schools in Hong Kong. The participating parents were asked to complete a self-administered questionnaire concerning their children's diet and oral health habits. The children were examined for caries status with WHO criteria by 3 calibrated examiners. Detection of dental erosion followed Basic Erosive Wear Examination (BEWE) criteria. RESULTS: A total of 704 children were recruited and 600 (316 boys, 53%) participated in the survey. There were 124 children (21%) with caries experience (DMFT > 0) and their DMFT was 0.34 ± 0.76. About half of their decay was unfilled (DT = 0.16 ± 0.52) The DMFT of girls and boys were 0.45 ± 0.89 and 0.23 ± 0.61, respectively (p = 0.001). Girls also had a higher DT (0.21 ± 0.62 compared with 0.11 ± 0.41, p = 0.013) and FT than boys (0.23 ± 0.63 compared with 0.12 ± 0.44, p = 0.016). Most children (75%) had at least some sign of erosion (BEWE > 0), but no severe erosion (BEWE = 3). Logistic regression showed girls who consumed soft drinks and took vitamin C supplements had higher caries risk. Dental erosion was more severe among the children who had caries experience and consumed fruit juice. CONCLUSIONS: The 12-year-old Hong Kong children had low caries experience, and almost half of the decay was left untreated. Although severe erosion was not found, many children had early signs of erosion.