In vitro remineralization of adjacent interproximal enamel carious lesions in primary molars using a bioactive bulk-fill composite.

BACKGROUND: Surface remineralization is recommended for the management of active non-cavitated interproximal carious lesions in primary teeth. According to the American Academy of Pediatric Dentistry, a recently recognized category of materials called bioactive restorative materials can be used for remineralization. This study aimed to evaluate the release of fluoride (F), calcium (Ca) and phosphate (P) ions from Predicta® Bioactive Bulk-fill composite compared with EQUIA Forte® and Filtek™ Z350 and to determine the remineralization effect of these 3 restorative materials on adjacent initial interproximal enamel carious lesions. METHODS: The release of F, Ca and P ions from 3 groups ((n = 10/group) (Group 1- Predicta®, Group 2- EQUIA Forte® and Group 3- Filtek™ Z350)) was determined at 1st, 4th, 7th and 14th days. After creating artificial carious lesions, human enamel samples were randomly assigned into 3 groups (n = 13/group) which were placed in contact with occluso-proximal restorative materials and exposed to a 14-day pH cycling period. Surface microhardness was determined using a Knoop microhardness assay at baseline, after artificial carious lesions formation and after pH cycling. The difference in the percentage of surface microhardness recovery (%SMHR) among groups was compared. Mineral deposition was analyzed with energy-dispersive x-ray spectroscopy (EDS) and the enamel surface morphology was evaluated with scanning electron microscopy (SEM). Kruskal-Wallis's test with Dunn's post hoc test and one-way ANOVA with Tukey's post hoc test were used for data analysis. RESULTS: EQUIA Forte® released the highest cumulative amount of F and P ions, followed by Predicta® and Filtek™ Z350. Predicta® released higher amount of Ca ions than EQUIA Forte® and Filtek™ Z350. Predicta® demonstrated the highest %SMHR, followed by EQUIA Forte® and Filtek™ Z350. There was a significant difference in the %SMHR between Predicta® and Filtek™ Z350 (p < 0.05). However, EQUIA Forte® demonstrated the highest fluoride content, followed by Predicta® and Filtek™ Z350. The SEM images of EQUIA Forte® and Predicta® revealed the greater mineral deposition. CONCLUSION: Predicta® demonstrated a marked increase in surface microhardness and fluoride content of adjacent initial interproximal enamel carious lesions in primary molars compared with Filtek™ Z350. Predicta® is an alternative restorative material to remineralize adjacent initial interproximal enamel carious lesions in primary molars, especially in high-risk caries patients.

An alkasite restorative material effectively remineralized artificial interproximal enamel caries in vitro.

OBJECTIVE: To evaluate the remineralization of artificial interproximal enamel caries (AIEC) adjacent to alkasite, high viscous glass ionomer cement (HVGIC), and resin composite in class II restorations. MATERIALS AND METHODS: Human enamel specimens were randomly assigned to 3 groups (n = 22): Filtek™ Z350, EQUIA Forte®, and Cention N®. The baseline hardness was determined using a Knoop microhardness assay. AIEC was formed in the specimens, and they were placed in contact with the proximal restorative materials then subjected to a 7-day pH cycling. Microhardness was determined post-artificial caries formation and post-pH cycling. The differences in the percentage of surface hardness recovery (%SHR) between the groups were compared using the Kruskal-Wallis test. The Dunn's test was used for between-group comparisons (p < 0.05). Specimen surface morphology was evaluated using scanning electron microscopy (SEM), and the calcium, phosphorus, and fluoride contents were analyzed by energy-dispersive spectroscopy (EDS). ANOVA with the post hoc Tukey multiple comparison test was used to evaluate the differences between groups (p < 0.05). RESULTS: The Cention N® %SHR was the highest, followed by EQUIA Forte®, and Filtek™ Z350. There was a significant difference in the %SHR between Cention N® and Filtek™ Z350 (p < 0.05). In contrast, there were no significant difference between Cention N® and EQUIA Forte®. Significantly increased enamel surface fluoride content was observed in the Cention N® compared with Filtek™ Z350 specimens (p < 0.05). The SEM image of the Cention N® specimens demonstrated the greatest mineral deposition. CONCLUSIONS: Cention N® markedly increased the surface hardness and fluoride content of adjacent AIEC compared with Filtek™ Z350 restorations. CLINICAL RELEVANCE: Cention N® is a promising alternative restorative material to remineralize initial enamel lesions in approximal adjacent surfaces, especially in high-risk caries patients.

Fluoridated milk enhances the mineral density of artificial proximal carious lesions in situ.

OBJECTIVE: To compare the mineral density (MD) of non-fluoridated-milk (non-F-milk), fluoridated-milk (F-milk), adjunctive to 1000-ppm-fluoride dentifrice (FD), and 1000-ppm-FD alone of proximal artificial enamel carious lesions (AECL) in high caries-risk patients. MATERIALS AND METHODS: This double-blind, cross-over in situ study comprised seven high caries-risk volunteers. Orthodontic brackets with one slab of AECL were fixed randomly to each volunteer per phase. The study comprised three experimental periods with a 7-d wash-out period using FD between sessions; (1) A four-week tooth brushing with FD 2×/day by all subjects as a control. The participants were then randomly allocated to (2) drinking 2.5-ppm-F-milk 1×/day or (3) non-F-milk 1×/day, adjunctive to tooth-brushing with FD for 4-weeks. The subjects crossed over from each type of milk and continued the same protocol for another four weeks. After each phase, the MD of each specimen was analyzed using micro-computed tomography (Micro-CT). RESULTS: The baseline MD was not significantly differences (p = .653). When brushing with FD and drinking F-milk, the MD gain was significantly higher (11.68 ± 2.89%) compared with brushing with FD and drinking non-F-milk (4.59 ± 1.78%) (p = .003) or brushing with FD alone (5.30 ± 2.10%) (p = .003). CONCLUSIONS: F-milk adjunctive to FD significantly increased MD gain compared with non-F-milk + FD or FD alone.

Comparative Study of Oral Health Education Given by a Dentist and Schoolteachers in Thai Grade 3 Students.

OBJECTIVES: To compare children's knowledge and attitudes toward oral health (OH) and plaque score after receiving OH education (OHE) from a dentist or trained schoolteachers. MATERIALS AND METHODS: Third-grade students in Amphoe Meuang, Nakhon Phanom, Thailand (n = 652), were randomly divided into a dentist group (n = 217), a teacher group (n = 216), and a control group (n = 219). The students' OH knowledge, attitudes, and plaque scores before the intervention were collected as baseline data. The dentist and the teacher groups received additional OH education sessions by a dentist and trained schoolteachers, respectively. Their immediate post-test knowledge was evaluated after each session, and plaque scores were determined after the brushing session. All groups continued a monthly tooth brushing activity for two months. The final assessment was done at the three-month follow-up. RESULTS: The students who received additional OHE by either a dentist or teacher demonstrated improved knowledge and attitudes towards OH, including plaque score. Interestingly, at the three-month follow-up, the knowledge score in the teacher group was significantly higher than in the dentist group. However, the dentist group had a significantly lower plaque score compared with the teacher group. CONCLUSIONS: Additional OHE in school significantly improved students' OH knowledge and positive attitudes regardless of the provider. However, the teacher tends to have a greater impact on their students; thus after appropriate training, schoolteachers can be efficient OH educators, especially in the long term.

Oral Health Education Improved Oral Health Knowledge, Attitudes, and Plaque Scores in Thai Third-grade Students: A Randomised Clinical Trial.

PURPOSE: To compare students' knowledge, attitudes towards oral health, and plaque scores after oral health education sessions delivered by trained schoolteachers vs the control group. MATERIALS AND METHODS: The participants, comprising third-grade students in Amphoe Meuang, Nakhonphanom province (N = 435), were randomly divided into an experimental group (n = 216) and a control group (n = 219). Baseline data of the students' oral health knowledge, attitudes, and plaque scores were collected at the beginning of the study. The experimental group was given oral health education sessions by trained schoolteachers using a specifically designed student handbook, while the control group did not receive extra oral health education other than the national curriculum. The immediate post-test knowledge was evaluated after each session, and plaque scores were determined after the brushing session. After the oral health education programme ended, the experimental and control groups performed a monthly toothbrushing activity for 2 months. Final assessment of the students' knowledge, attitudes, and plaque score was done at the 3-month follow-up. RESULTS: The experimental group's oral health knowledge statistically significantly improved immediately after each session and was still statistically significant during the following three months. This improvement was also statistically significantly higher compared with the control group. The attitudes towards oral health care, foods related to caries, and dental visit improved. The plaque score of the experimental group was statistically significantly lower immediately post-brushing, but was not statistically significantly different at the 3-month follow-up compared with baseline. CONCLUSION: The children receiving oral health education provided by trained schoolteachers had statistically significantly greater oral health knowledge and more positive attitudes towards oral health than the children who had not received the programme. No statistically significant differences in plaque scores were found after 3 months.

Cobalt Chloride Enhances the Stemness of Human Dental Pulp Cells.

INTRODUCTION: Hypoxia is a factor in controlling stem cell stemness. We investigated if cobalt chloride (CoCl2), a chemical agent that mimics hypoxia in vitro, affected human dental pulp cell (hDPC) stemness by examining cell proliferation, stem cell marker expression, and osteogenic differentiation. METHODS: hDPCs were cultured with or without 25 or 50 µmol/L CoCl2. The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay was used to determine cell proliferation. The number of STRO-1+ cells was determined by flow cytometry. The messenger RNA expression of the stem cell markers REX1, OCT4, SOX2, and NANOG and the osteogenic-associated genes ALP, COLI, and RUNX2 were evaluated using reverse transcription polymerase chain reaction or real-time polymerase chain reaction. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) activity and mineralization assays. RESULTS: Although 25 and 50 µmol/L CoCl2 suppressed hDPC proliferation, 50 µmol/L CoCl2 increased the number of STRO-1+ cells. Moreover, CoCl2 dose dependently induced stem cell marker expression. Additionally, CoCl2 treatment suppressed osteogenic-associated gene expression, ALP activity, and calcium deposition. The addition of apigenin, a hypoxia-inducible factor 1-alpha inhibitor, reversed the inhibitory effect of CoCl2 on ALP activity. CONCLUSIONS: This study indicated that CoCl2 may enhance hDPC stemness.

Cobalt chloride supplementation induces stem-cell marker expression and inhibits osteoblastic differentiation in human periodontal ligament cells.

OBJECTIVE: Low oxygen tension is one of the crucial factors of the stem-cell niche. However, the long-term hypoxic culture of stem cells is difficult and requires special equipment. In this study, we investigated whether mimicking hypoxia using cobalt chloride (CoCl2) could maintain human periodontal ligament (HPDL) cell stemness. METHODS: HPDL cells were treated with either 50 or 100 µM CoCl2. Cell proliferation was determined by an MTT assay. The mRNA expression of stem-cell marker and osteogenic associated genes were analyzed by RT-PCR and Real-time PCR. Osteogenic differentiation was determined by assaying alkaline phosphatase activity and in vitro mineralization. RESULTS: The results showed that the CoCl2 supplementation had no effect on cell proliferation. CoCl2 treatment increased the mRNA expression of the embryonic stem-cell markers REX1 and OCT4. Culturing HDPL cells in osteogenic medium containing CoCl2 resulted in a decrease in alkaline phosphatase activity, down-regulation of osteogenic associated gene expression, and suppression of mineralization. The use of Apigenin, an HIF-1α inhibitor, indicated that CoCl2 might inhibit osteogenic differentiation through an HIF-1α- dependent mechanism. CONCLUSION: This study shows that CoCl2 treatment can induce stem-cell marker expression and inhibit the osteoblastic differentiation of HPDL cells. These findings suggest the potential application of CoCl2 for maintaining the stem-cell state in the laboratory.

TGF-ß in dentin matrix extract induces osteoclastogenesis in vitro.

Previously, we have demonstrated that the extracellular matrix from dentin affects osteoclastic activity in co-culture between osteoclast and osteoblast-rich fraction from mouse marrow cells. In the present study, we aimed to investigate the mechanisms of dentin matrix extract-induced osteoclastogenesis in mouse bone marrow macrophages (BMMs). Dentin proteins were extracted from bovine incisor root dentin using 0.6 M HCl. BMMs were cultured in α-MEM containing macrophage colony-stimulating factor/receptor activator of nuclear factor kappa-B ligand in the presence or absence of dentin matrix extract. Tartrate-resistant acid phosphatase (TRAP)-positive cell number, total TRAP activity, and the mRNA levels of osteoclast-related genes, assayed by real-time RT-PCR, were determined as markers of osteoclastogenesis. A neutralizing antibody against transforming growth factor-ß1 (TGF-ß1), SB431542, a TGF-ß receptor inhibitor, and ELISA were used to determine the role of TGF-ß1. We observed increases in TRAP-positive cell number, TRAP activity, and the mRNA levels of osteoclast-related genes of BMMs cultured with dentin extract. The use of a neutralizing antibody against TGF-ß1 or SB431542 inhibited the inductive effect of dentin extract, suggesting TGF-ß1 involvement. The addition of exogenous TGF-ß1, but not bone morphogenic protein-2, also increased osteoclastogenesis, corresponding to the ELISA determination of TGF-ß1 in the dentin extract. In conclusion, our results indicate that proteins from dentin matrix have an inductive effect in osteoclastogenesis, which is mediated, in part, by TGF-ß1.