Effect of silver diamine fluoride on vital dental pulp: A systematic review.

OBJECTIVE: This study aims to review systematically the dental pulp response to silver diamine fluoride (SDF) treatment, including the inflammatory response, pulp cells activity, dentinogenesis, silver penetration, and the presence of the bacteria in the dental pulp. DATA: In vitro studies, animal studies, clinical studies, and case reports on the use of SDF on vital dental pulp were included. Quality assessment of the included studies was conducted. A narrative synthesis of the collected data was performed. SOURCES: A systematic search was performed in ProQuest, PubMed, SCOPUS, and Web of Science databases for articles published from inception to Nov 1, 2021. STUDY SELECTION: The initial search identified 1,433 publications, of which five publications met the inclusion criteria. These five publications reported the effect of direct/ indirect SDF application on the vital pulp of a total of 30 teeth. Direct SDF application on vital pulp caused pulp necrosis. Indirect SDF application caused none or mild inflammatory response of dental pulp. The odontoblasts in the dental pulp showed increased cellular activity. Tertiary dentine was formed in the pulpal side of the cavity with indirect SDF application. Accentuated incremental lines of tertiary dentine reflected disturbances in mineralisation. Silver ions were found to penetrate along the dentinal tubules but were not detected inside the pulp. CONCLUSION: According to the limited available literature, direct SDF application causes pulp necrosis. Indirect SDF application is generally biocompatible to dental pulp tissue with a mild inflammatory response, increased odontoblastic activity, and increased tertiary dentine formation. Future studies with precise quantitative and qualitative tests, larger sample size and longer follow-up time are imperative to understand the biological activity of dental pulp to SDF treatment.

Metal and Metal Oxide Nanoparticles in Caries Prevention: A Review.

Nanoparticles based on metal and metallic oxide have become a novel trend for dental use as they interfere with bacterial metabolism and prevent biofilm formation. Metal and metal oxide nanoparticles demonstrate significant antimicrobial activity by metal ion release, oxidative stress induction and non-oxidative mechanisms. Silver, zinc, titanium, copper, and magnesium ions have been used to develop metal and metal oxide nanoparticles. In addition, fluoride has been used to functionalise the metal and metal oxide nanoparticles. The fluoride-functionalised nanoparticles show fluoride-releasing properties that enhance apatite formation, promote remineralisation, and inhibit demineralisation of enamel and dentine. The particles' nanoscopic size increases their surface-to-volume ratio and bioavailability. The increased surface area facilitates their mechanical bond with tooth tissue. Therefore, metal and metal oxide nanoparticles have been incorporated in dental materials to strengthen the mechanical properties of the materials and to prevent caries development. Another advantage of metal and metal oxide nanoparticles is their easily scalable production. The aim of this study is to provide an overview of the use of metal and metal oxide nanoparticles in caries prevention. The study reviews their effects on dental materials regarding antibacterial, remineralising, aesthetic, and mechanical properties.

Perspective of students in the Global Citizenship in Dentistry as an international peer learning experience.

OBJECTIVE: To explore the achievement and perception of dental students in an international peer learning setting via the Global Citizenship in Dentistry (GCD) program. METHODS: In the GCD program, year-2 dental students from universities in Egypt, Hong Kong, Malaysia, UK, and the United States developed a portfolio of a restorative procedure in simulation laboratory and uploaded to an online platform (https://gcd.hku.hk/). Through the platform, the students left comments on each other's portfolios to share and discuss their knowledge and experiences on restorative dentistry. This study invited students from Hong Kong in 2018-2019 to complete an open-ended questionnaire to explore their experience on the GCD program. The feedback was compiled and analyzed. RESULTS: All 71 year-2 students completed the questionnaire. Their most dominant comments were positive feelings about learning different clinical principles and methods from universities abroad. The students also enjoyed the cultural exchange from the comfort of their own devices. Other recurrent comments included the improvement of the skills of communication and comments on the peers' work in a professional manner. The students were enthusiastic about being able to apply their critical thinking in evaluating their work. They shared their learning barriers, including the extra time needed for the program, some unenthusiastic responses from groupmates, and delayed replies from peers. They made suggestions to remove the barriers in the learning process of the GCD program. CONCLUSION: Students generally welcomed the GCD program and benefitted from the global academic exchange, development of critical thinking, enhancing professional communication skills, as well as opportunities of cultural exchange.

Caries-arresting effects of silver diamine fluoride and sodium fluoride on dentine caries lesions.

OBJECTIVES: To investigate the remineralising effect and bacterial growth inhibition of 38% silver diamine fluoride (SDF) solution and 5% sodium fluoride (NaF) varnish on artificial dentine caries lesions. METHODS: Demineralised dentine blocks were treated with SDF + NaF (Group 1), SDF (Group 2), NaF (Group 3) and water (Group 4) and subjected to a Streptococcus mutans biofilm challenge. Lesion depth, precipitates' characteristics and matrix (collagen)-to-mineral ratio were evaluated by micro-computer tomography (micro-CT), X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR), respectively. The biofilm kinetics, viability and topography were assessed by counts of colony forming units (CFUs), confocal laser scanning microscopy (CLSM) and scanning electron microscopy (SEM), respectively. Data were analysed by two-way ANOVA test. RESULTS: The lesion depths of Groups 1-4 were 170 ± 28 µm, 160 ± 32 µm, 353 ± 38 µm and 449 ± 24 µm, respectively. The addition of NaF to SDF did not show better remineralisation than SDF (p = 0.491). Metallic silver and silver chloride were found in Groups 1 and 2. The amide I-to-hydrogen phosphate ratios of the four groups were 0.14 ± 0.02, 0.14 ± 0.01, 0.29 ± 0.05 and 0.49 ± 0.16, respectively, and the addition of NaF to SDF did not offer better protection against collagen exposure than SDF (p = 0.986). The Log10 CFUs of Groups 1-4 were 5.75 ± 0.56, 4.49 ± 0.57, 6.55 ± 0.39 and 6.40 ± 0.38, respectively. The presence of NaF reduced the antibacterial effect of SDF (p < 0.001). The SEM and CLSM images supported the findings. CONCLUSION: Application of SDF with or without NaF reduced the demineralisation of dentine caries, but SDF exerted stronger inhibition of biofilm growth than SDF with NaF. CLINICAL SIGNIFICANCE: NaF varnish affects the antibacterialeffects of SDF, the adjunctive application of SDF solution and NaF varnish is not recommended to arrest dentine caries in clinic.