Caries Incidence and Its Associated Factors in Hong Kong Kindergarten Children.

OBJECTIVE: The study aimed to investigate caries incidence and its associate factors among kindergarten children in Hong Kong. METHOD: This 30-month prospective study recruited 3- to 4-year-old children when they started their kindergarten study. A self-administered parental questionnaire survey was used to collect the children's social demographic information and their oral health-related habits. Child's caries experience was recorded using the decayed, missing, and filled tooth (dmft) index and the visible plaque index (VPI) was used to measure their oral hygiene status. A final examination was performed after 30 months when they were in the final year of kindergarten. Data were analysed using the zero-inflated negative binomial (ZINB) regression model. RESULTS: This study examined 660 children at baseline and 501 children at the final examination (dropout 24%). At baseline, the caries prevalence among 501 children was 23%, with mean (SD) dmft scores of 0.7 (1.8). At the final examination, caries prevalence increased to 41%, with mean (SD) dmft scores of 1.6 (2.8). The 30-month incidence rate was 34%, and the mean (SD) number of new carious teeth developed was 0.9 (1.7). Lower first molars exhibited the highest caries increment rate (11%), followed by upper second molars (9%) and upper central incisors (9%). ZINB regression analysis revealed associations among caries incidence and family income, baseline dmft, and baseline VPI (P < .05). CONCLUSIONS: One third of Hong Kong kindergarten children developed new caries. Low family income, prior caries experience and poor oral hygiene were the significant factors associated with their caries incidence. CLINICAL RELEVANCE: Many children developed new caries during their kindergarten years, with their caries experience more than doubling. Preventive measures, including oral health education and reinforcing oral hygiene practice in kindergarten, are essential to reduce their caries incidence, particularly for children with low family income, caries experience and poor oral hygiene.

Early Childhood Caries and Dental Public Health Programmes in Hong Kong.

The objective of this study was to investigate the relationship amongst early childhood caries (ECC), economic development, and dental public health programmes in Hong Kong. We searched exhaustively qualitative and quantitative data on the oral health policy, dental service, public health strategies of caries control and epidemiologic surveys on ECC. We then performed meta-regression to explore the impact of the Human Development Index (HDI), gross domestic product (GDP) growth, water fluoridation, oral health promotion, dental school establishment, free education, and dental workforce on ECC prevalence in 5-year-olds. We found that the first government oral health survey was conducted in 1960, when Hong Kong experienced significant growth, as the HDI indicated. The survey revealed that 97% of 6- to 8-year-old children experienced ECC. Water fluoridation was implemented in 1961 at 0.7 ppm (0.9 ppm in winter) to prevent caries. The government offered free 9-year education in 1978. In 1981, the government established a dental school to improve a low dentist-to-population ratio of 1:9000. The ECC prevalence amongst 5- to 6- year-old children was reduced from 84% in 1968 to 63% in 1986. The Department of Health created an oral health education division in 1989. The ECC prevalence for 5-year-old children was further reduced to 44% in 1997. The ECC prevalence amongst 5-year-old children was stabilised at 51% both in 2001 and 2011. However in 2021, the prevalence of untreated ECC increased to 57% during the outbreak of COVID-19. Meta-regression analysis showed that ECC prevalence was not linked to GDP growth but decreased with improvements in HDI, the provision of 9-year free education, the establishment of a dental school, fluoridation of water supply, and implementation of territory-wide oral health promotion. In conclusion, better education, living conditions, and dental public health programmes have improved children's oral health in Hong Kong.

Stability of Silver and Fluoride Contents in Silver Diamine Fluoride Solutions.

OBJECTIVE: This study aims to determine the stability, alkalinity, and fluoride and silver ion concentrations of 5 commercially available 38% silver diamine fluoride (SDF) solutions-namely Advantage Arrest, e-SDF, Riva Star, Saforide, and Topamine-in 180 days. METHODS: Alkalinity was determined using a pH electrode. The fluoride and silver ion concentrations were obtained using a calibrated ion-selective electrode and optical emission spectrometer, respectively. Six bottles of each product were examined on days 0 (freshly opened), 30, 60, 90, and 180. The time taken for each freshly opened product to form a black silver precipitate under room light (500 lx) and 25 °C was also recorded. RESULTS: For 180 days, Advantage Arrest, e-SDF, Riva Star, Saforide, and Topamine had the pH range of 9.8-9.8, 10.5-10.6, 13.0-13.1, 9.8-9.8, and 9.3-9.4; fluoride ion concentration range (nearest 1000 ppm) of 40.9%-42.4%, 46.7%-50.9%, 37.0%-39.0%, 37.0%-45.7%, and 47.7%-53.4%; silver ion concentration range (nearest 1000 ppm) of 283.4-307.0, 307.3-315.4, 418.6-435.7, 266.3-281.0, and 416.2-456.1 ppm; and precipitation time (nearest hour) of 17, 12, 6, 7, and 7 hours, respectively. The percentage change of fluoride and silver could be more than 5% after 60 days. CONCLUSIONS: The alkalinity of the 5 SDF solutions remained stable after 180 days. In addition, their fluoride and silver concentrations decreased substantially after 60 days. The freshly opened SDF solutions did not precipitate within 5 hours under ambient room conditions. The alkalinity and fluoride and silver concentrations of the 38% SDF solutions could be less stable after 60 days; thereafter, the fluoride and silver concentrations decreased. Thus, the SDF solution should be used within 60 days after opening.

Caries Prevention Using Silver Diamine Fluoride: A 12-Month Clinical Trial.

OBJECTIVE: This clinical trial aimed to compare the caries-preventive effect of annual application of 38% silver diamine fluoride solution (SDF) with 5% sodium fluoride varnish (FV) to the anterior primary teeth of children. The hypothesis was that SDF was superior to FV at 1 year. Secondary objectives were to determine the child's cooperation and the parent's satisfaction and assess adverse effects. METHOD: We recruited 688 3- to 4-year-old children and randomly allocated them to receive SDF or FV (positive control) on their 6 upper anterior teeth. Tooth-surface status was recorded using the decayed, missing, and filled surfaces index. A trained observer rated the child's cooperation as "totally cooperative" or "not totally cooperative." We used a questionnaire to determine the parent's satisfaction as "satisfied," "neutral," or "dissatisfied." Adverse effects (yes/no) were evaluated 1 day and about 1 year after treatment. RESULTS: Of the children, 434 (SDF, n = 209; FV, n = 225) completed the trial. The mean new decayed tooth surfaces developed for SDF and FV groups were 0.4 ± 1.5 and 0.4 ± 1.3, respectively (P = .65). Child's cooperation for SDF and FV therapy was 71% (244/344) and 70% (241/344), respectively (P = .89). Parent's satisfaction for SDF and FV therapy was 71% (148/209) and 69% (155/225), respectively (P = .29). Adverse effects were found neither at 1 day nor at about 1 year after treatment for either treatment arm. CONCLUSIONS: SDF is not superior to FV for caries prevention in primary upper anterior teeth at 1-year follow-up. Child's cooperation and parent's satisfaction were similarly high with SDF and FV therapy at 1-year follow-up. Neither short-term nor long-term adverse effects were observed. This study is registered at ClinicalTrials.gov (NCT04399369).

Silver diamine fluoride therapy for dental care.

Silver diamine fluoride (SDF) was developed in Japan in the 1960s. It is used to control early childhood caries, arrest root caries, prevent fissure caries and secondary caries, desensitise hypersensitive teeth, remineralise hypomineralised teeth, prevent dental erosion, detect carious tissue during excavation and manage infected root canals. SDF is commonly available as a 38% solution containing 255,000 ppm silver and 44,800 ppm fluoride ions. Silver is an antimicrobial and inhibits cariogenic biofilm. Fluoride promotes remineralisation and inhibits the demineralisation of teeth. SDF also inactivates proteolytic peptidases and inhibits dentine collagen degradation. It arrests caries without affecting dental pulp or causing dental fluorosis. Indirect pulp capping with SDF causes no or mild inflammatory pulpal response. However, direct application of SDF to dental pulp causes pulp necrosis. Furthermore, SDF stains carious lesions black. Patients must be well informed before SDF treatment. SDF therapy is simple, painless, non-invasive, inexpensive, and requires a simple armamentarium and minimal support. Both clinicians and patients generally accept it well. In 2021, the World Health Organization included SDF as an essential medicine that is effective and safe for patients. Moreover, it can be used for caries control during the COVID-19 pandemic because it is non-aerosol-generating and has a low risk of cross-infection.

A Review of the Protocol of SDF Therapy for Arresting Caries.

OBJECTIVE: The aim of this work was to review the protocol of the use of silver diamine fluoride (SDF) for arresting caries, specifically the application time. METHOD: Two researchers searched manufacturers' instructions, YouTube videos, and 5 databases (Embase, Medline, PubMed, Scopus, and Web of Science). Manufacturers' instructions, videos from national dental organisations, and peer-reviewed journal articles that published the SDF application protocol in English for arresting caries were selected. RESULTS: The review included 14 protocols from 15 publications from 4 manufacturers, 3 dental associations, and 7 author teams (one team had 2 articles). The American Dental Association and the British Society of Paediatric Dentistry provided their SDF application protocols on YouTube. The American Academy of Paediatric Dentistry and 7 author teams published their protocols in journal articles. Seven publications suggested an SDF application time of 60 seconds. Seven publications suggested a time range of 10 seconds to 240 seconds. Two publications suggested caries excavation, but 4 publications suggested no caries excavation before SDF application. The procedures from at least 5 publications involved protecting the gingiva with petroleum jelly, isolating the carious tooth with cotton rolls, drying the carious lesion with a 3-in-1 syringe, applying SDF solution with a micro brush for 60 seconds, removing excess SDF solution with gauze, and applying fluoride varnish to the SDF-treated lesion. CONCLUSIONS: Although the SDF application protocol is simple and straightforward, the published protocols could be different. Most publications suggested an SDF application time of 60 seconds, which can be long, particularly for young children and older adults.

Ion Concentration of Silver Diamine Fluoride Solutions.

OBJECTIVE: The aim of this work was to determine the free fluoride and silver ion concentrations and the alkalinity of 4 commercially available 38% silver diamine fluoride (SDF) solutions. METHODS: Four common brands of 38% SDF solutions, namely Saforide, Advantage Arrest, e-SDF, and Topamine, were selected. Three bottles of each brand of SDF solution from the same lot were assessed. Measurements of the silver and fluoride content and alkalinity were performed directly when a bottle was opened. Each measurement was repeated to recheck its reliability. The free fluoride ion concentrations were measured using a calibrated ion-selective electrode. The free silver ion concentrations were measured using optical emission spectrometry. The alkalinity of the SDF solution was determined with a pH electrode. RESULTS: The mean concentrations of fluoride ions of the Saforide, Advantage Arrest, e-SDF, and Topamine were 43,233 ppm, 44,333 ppm, 51,370 ppm, and 54,400 ppm, respectively; their percentage differences from the expected value (44,800 ppm) were 3.5%, 2.4%, 14.7%, and 21.4%, respectively. The mean concentrations of silver ions of the Saforide, Advantage Arrest, e-SDF, and Topamine were 258,841 ppm, 260,016 ppm, 336,149 ppm, and 319,966 ppm, respectively; their percentage differences from the expected value (253,900 ppm) were 3.2%, 5.8%, 32.4%, and 25.9%, respectively. The 4 products had pH values of 9.2, 9.1, 9.2, and 9.0, respectively. CONCLUSIONS: This study showed differences between the claimed and measured fluoride and silver ion concentrations in 4 common 38% SDF products, which were alkaline with a pH value of 9.

Fluoride Delivered via a Topical Application of 38% SDF and 5% NaF.

OBJECTIVES: The objectives of this study were to compare the amount of fluoride delivered via a topical application of 38% silver diamine fluoride (SDF) solution and 5% sodium fluoride (NaF) varnish as well as to determine the amount of 38% SDF solution delivered using various micro-applicators. METHODS: The weights of 38% SDF (Saforide) and 5% NaF (Duraphat) applied to the occlusal surface of an extracted human upper first premolar with a regular-size (2.50-mm tip diameter) micro-applicator were measured using an electronic-analytical balance. Afterwards, the weight of 38% SDF applied to a premolar using the micro-applicators of 5 common brands (Premium Plus, 3M, Dentsply, Elevate Oral Care, and SDI) were studied. The tip diameter of each micro-applicator was measured under a microscope. The weights of the delivered fluoride and silver were also calculated. RESULTS: The mean weights of the fluoride delivered via the SDF solution and NaF varnish were 0.25 ± 0.07 mg and 0.49 ± 0.08 mg, respectively (P < .001). In addition, the tip diameters of the micro-applicators ranged from 1.89 ± 0.03 mm to 2.76 ± 0.02 mm. The mean weights of the fluoride delivered per application of 38% SDF using different applicators ranged from 0.13 ± 0.06 mg to 0.30 ± 0.09 mg, whereas the mean weights of the silver ranged from 0.76 ± 0.32 mg to 1.68 ± 0.50 mg. The weights of the delivered 38% SDF solution varied with the brand and with the tip diameters of the dental micro-applicators (P < .001). CONCLUSIONS: The fluoride of the 38% SDF solution delivered topically was significantly less than that of 5% NaF varnish. Moreover, the amount of SDF solution delivered depends on the brand and size of the micro-applicators.

Effect of application time of 38% silver diamine fluoride solution on arresting early childhood caries in preschool children: a randomised double-blinded controlled trial protocol.

BACKGROUND: To study the caries lesion activity response to topical 38% silver diamine fluoride (SDF) therapy with increasing treatment application time. METHODS/DESIGN: The design is a stratified-randomised, double-blind, active-controlled, parallel-group clinical trial with nine treatment arms. The trial will involve recruiting at least 414 3- to 5-year-old kindergarten children with caries, who will receive approximately 0.004 mL of 38% SDF (the typical amount applied per the manufacturer's instructions) to treat each caries lesion. The children will be stratified by caries status, randomised by blocks, and allocated to nine groups of SDF application times: 3, 5, 10, 15, 30, 45, 60, 120, and 180 s. The outcome measure is caries lesion activity (active/arrest) at the tooth-surface level at 6 months post-initial treatment. A calibrated dentist will conduct the blinded clinical examinations at baseline and at the 6-month follow-up. In addition, the parents will be surveyed to examine the effects of the moderating variables, such as oral hygiene, on caries lesion activity. The hypothesis is that a monotonically increasing trend can be found between the SDF application time and the proportion of caries lesions that are arrested. The Cochran-Armitage test for trends in proportions, corrected for clustering within children, will be used to determine the relationship between the exposure to SDF (the SDF application time) and the response (proportion of lesions arrested) in children, taking into consideration the effect of the moderating variables as well as the nesting of multiple caries lesions within an individual child. An EC 80 analysis (an 80% maximal concentration) will be used to determine the exposure (the SDF application time) for 80% caries lesion arrest. Bootstrap methods will be used for clustered data and will be resampled by clustering to determine the 95% confidence interval. DISCUSSION: This study will help with determining the optimal application time for SDF treatment. It will provide an evidence-based protocol for the use of SDF to arrest tooth decay in the primary teeth of young children. The results will inform an evidence-based SDF protocol to arrest caries, which affects 573 million children with tooth decay worldwide. TRIAL REGISTRATION: ClinicalTrials.gov NCT04655430 . Registered on 7th December 2020.

Prevalence of Untreated Early Childhood Caries of 5-Year-Old Children in Hong Kong: A Cross-Sectional Study.

This cross-sectional survey investigated untreated early childhood caries (ECC) and its associated factors among 5-year-old children in Hong Kong. Children were recruited using a multistage sampling method. One dentist examined the children in kindergarten to diagnose untreated ECC (dt) at the cavitation level. Each child's demographic information, snacking behaviour, and oral health-related practice were collected using a parental questionnaire. The relationships between the untreated ECC and demographic information, snacking behaviours, and oral health--related practice were analysed by zero-inflated negative binomial (ZINB) regression analysis. This survey recruited 404 children. Their dt score was 2.8 ± 3.8. The significant untreated ECC (SiUC) index, which was one-third of the children with the highest dt score, was 7.1 ± 3.6. Their untreated ECC prevalence was 57%, which was associated with the district the child lived in. Most children with untreated ECC (71%, 164/231) had never visited a dentist. Children who brushed without toothpaste had more untreated ECC. Children coming from low-income families and with a lower maternal education level had a higher risk of ECC. In conclusion, untreated ECC was prevalent and unevenly distributed among 5-year-old children in Hong Kong. Its prevalence was associated with toothpaste use, family income, maternal education level and the district they lived in.