A randomised clinical study to evaluate experimental children's toothpastes in an in-situ palatal caries model in children aged 11-14 years.

OBJECTIVES: To compare three children's sodium fluoride toothpastes to placebo with respect to enamel remineralisation potential, enamel fluoride uptake and net acid resistance using an in situ palatal caries model in children aged 11-14 years following a single brushing. DESIGN: This was a randomised, single blind (laboratory analyst), single-centre, four-treatment, crossover study with a 7-day washout period between treatments. The treatments were 1,426 ppm fluoride, 1,000 ppm fluoride, 500 ppm fluoride and 0 ppm fluoride (placebo) toothpaste (NaF/silica). A custom made in situ palatal appliance was used by each subject in all treatment periods. At each of the four treatment visits subjects wore the appliance containing four partially demineralised human enamel specimens for 5 minutes and then brushed their teeth using a standardised procedure for 60 seconds under supervision using 1.0 g (±0.1 g) of their assigned toothpaste. After 4 hours the appliance was removed and enamel specimen recovered. This process was repeated until all subjects completed all four study treatment visits. Recovered enamel specimens were analysed for per cent surface microhardness recovery (%SMHR; Knoop) and enamel fluoride uptake (EFU; microdrill biopsy). Subsequently, specimens were demineralised in vitro to determine their % net acid resistance (%NAR; Knoop). RESULTS: All three fluoride toothpastes demonstrated significantly greater %SMHR, EFU and %NAR compared with 0 ppm F toothpaste. The model demonstrated a dose response over the range 0 to 1,426 ppm fluoride for %SMHR, EFU and %NAR. There was no significant difference between 500 ppm F and 1,000 ppm F for %SMHR and between 1,000 ppm F and 1,426 ppm F for %SMHR, EFU and %NAR. CONCLUSIONS: The present in situ study demonstrated that the children's fluoride toothpastes tested are capable of delivering cariostatic amounts of fluoride to early caries lesions following a single brushing.

A randomised clinical study to evaluate the effect of brushing duration on fluoride levels in dental biofilm fluid and saliva in children aged 4-5 years.

OBJECTIVES: To compare the effect of 40 seconds versus 2 minutes brushing on saliva and dental biofilm fluid fluoride in children ages 4-5 years over 1 hour. DESIGN: This was a single-blind, cross-over, randomised, two-period clinical study in healthy children. Three days before the start of each treatment subjects received a thorough brushing and then refrained from all oral hygiene procedures. At treatment visits, after collecting baseline biofilm and saliva samples, staff brushed the occlusal surfaces of the subject's posterior teeth with a pea-sized amount (0.25 g) of NaF/silica toothpaste for the randomised time. Samples were taken at 5 minutes, 15 minutes, 30 minutes and 60 minutes after brushing and analysed for fluoride using a microanalytical methodology. There was a minimum 4-day washout period between treatments. RESULTS: Log changes from baseline biofilm fluid and saliva fluoride were statistically significant (P < 0.05) for both brushing times at all post-brushing time-points [except 60 minutes saliva where P = 0.06 (t-test)]. Statistically significantly greater ln-AUC (area under the curve) was found for biofilm fluid and salivary fluoride after brushing for 2 minutes compared with brushing for 40 seconds over the 1-hour test period. There was a statistically significantly higher concentration of fluoride in the log change from baseline saliva levels after 5, 15, 30 and 60 minutes for the 2-minute brushing time compared with 40 seconds brushing time. There was no statistically significant difference in concentration of log change from baseline fluoride levels in biofilm fluid at each individual time-point (5, 15, 30 and 60 minutes) for the 2-minute brushing time compared with the 40-second brushing time, but significant differences were observed for 15, 30 and 60 minutes in favour of 2-minute brushing time when log biofilm fluid value was analysed. CONCLUSION: The findings provide further evidence for the benefits of increased duration of brushing with respect to fluoride delivery.

Early Lead Exposure Associated with Molar Hypomineralization.

Purpose: The purpose of this study was to determine the association between prenatal and early life exposure to lead and the presence of molar hypomineralization (MH) in a group of Mexican children. Methods: A subset of participants of the Early Life Exposure in Mexico to Environmental Toxicants (ELEMENTS) cohort study was examined for the presence of molar hypomineralization using European Academy of Pedi- atric Dentistry (EAPD) criteria. Prenatal lead exposure was assessed by K-ray fluorescence measurements of patella and tibia lead and by maternal blood lead levels by trimester and averaged over trimesters. Postnatal exposure was assessed by levels of maternal blood lead at delivery and child blood lead at 12 and 24 months. Results: A subset of 506 subjects from the ELEMENT cohorts (nine to 18 years old) were examined for MH; 87 subjects (17.2 percent) had MH. Maternal blood lead levels in the third trimester (odds ratio [OR] equals 1.08; 95 percent confidence interval [95% CI] equals 1.02 to 1.15) and averaged over three trimesters (OR equals 1.10; 95% CI equals 1.02 to 1.19) were significantly associated with MH status. None of the maternal bone lead or the child's blood lead parameters was significantly associated with the presence of MH (P>0.05). Conclusions: This study documents a significant association between prenatal lead exposure especially in late pregnancy and the odds of molar hypomineralization.

Retention of dental sealants placed on sound teeth and incipient caries lesions as part of a service-learning programme in rural areas in Mexico.

BACKGROUND: Dental sealants are an effective treatment for the prevention and management of caries. OBJECTIVE: To determine the retention of sealants placed in a rural setting in Mexico as part of an international service-learning (ISL) programme and to determine associations between dental sealant's retention and caries diagnosis at the time of sealant placement. METHODS: Children aged 6-15 were examined for dental caries, received sealants by dental students as part of an ISL programme, and were re-examined 4, 2, or 1 years after placement to assess sealant survival. Sealants were placed on permanent sound surfaces and enamel caries lesions [International Caries Assessment and Detection System (ICDAS) criteria]. Sealant survival was explored using Cochran-Mantel-Haenszel tests and multivariate prediction models. RESULTS: 219 (46%) of 478 (mean age = 10.53 SD = 5.11) children who had received sealants returned for a recall examination (mean age = 10.89 SD = 3.11). After 1-4 years, 96.4% to 60.6% of the sealants placed on sound teeth had survived, and for sealants placed on surfaces with enamel caries lesions (ICDAS 1-3), 94.2% to 55.6% had survived. Differences were not statistically significant. CONCLUSIONS: Sealants had survival rates comparable to those previously reported in the literature. Sealants placed on sound and enamel caries lesions had similar survival rates.

Caries prevalence and its association with brushing habits, water availability, and the intake of sugared beverages.

BACKGROUND. With Dental Caries being the most common disease amongst children in the world today, there is a need to fully understand risk factors that may be related to caries prevalence and how they could be best addressed. AIM. The aim of this study was to evaluate soda, juice, sugared-beverage intake, brushing habits, and community water source availability as they relate to the prevalence of both noncavitated and cavitated caries lesions in small rural villages in Mexico. DESIGN. The International Caries Detection and Assessment System (ICDAS) was used in children from small, isolated, villages in Mexico. Risk factors were assessed via questionnaires. RESULTS. Caries prevalence in the villages was very high, ranging from 94.7% to 100% of the children studied. The mean number of surfaces with lesions per child (D1MFS + d1mfs) having scores ≥1 (noncavitated and cavitated) ranged from 15.4 ± 11.1 to 26.6 ± 15.2. Many of the children reported drinking beverages containing sugar. CONCLUSIONS. Drinking sugared beverages, poor oral hygiene habits, and lack of access to tap water were identified as risk factor for caries in this sample of residents of rural Mexico.

An international, multidisciplinary, service-learning program: an option in the dental school curriculum.

INTRODUCTION: Many health professions students who treat Spanish-speaking patients in the United States have little concept of their culture and health related traditions. The lack of understanding of these concepts may constitute major barriers to healthcare for these patients. International service-learning experiences allow students to work directly in communities from which patients immigrate and, as a result, students gain a better understanding of these barriers. OBJECTIVE: This article describes the implementation of an international, multidisciplinary, service-learning program in a dental school in the United States. PROGRAM DESCRIPTION: The Indiana University International Service-Learning program in Hidalgo, Mexico began in 1999 as an alternative spring break travel and clinical experience for medical students, focusing on the treatment of acute health problems. Travel-related preparatory sessions were offered, and no learning or service objectives had been developed. The program has evolved to include a multidisciplinary team of dental, medical, nursing, public health and social work students and faculty. The experience is now integrated into a curriculum based on the service-learning model that allows students to use their clinical skills in real-life situations and provides structured time for reflection. The program aims to enhance teaching and foster civic responsibility in explicit partnership with the community. Preparatory sessions have evolved into a multidisciplinary graduate level course with defined learning and service objectives. PROGRAM EVALUATION METHODS: In order to assess the program's operation as perceived by students and faculty and to evaluate student's perceptions of learning outcomes, evaluation tools were developed. These tools included student and faculty evaluation questionnaires, experiential learning journals, and a strengths, weaknesses, opportunities and threats analysis. FINDINGS: Evaluation data show that after program participation, students perceived an increase in their cultural awareness, cross-cultural communication skills and understanding of barriers and disparities faced by Latinos in the United States. Faculty evaluations offer insights into the lessons learned through the implementation process. CONCLUSION: The development of a service-learning based curriculum has posed challenges but has enriched international service experiences.

Differences in exposure and biological markers of fluoride among White and African American children.

OBJECTIVE: To determine differences in self-reported fluoride exposure and fluoride exposure biomarkers between two racial groups. METHODS: Questionnaires regarding fluoride exposure, urine and water collection kits were distributed to African American and White 7-14-year-old children. Children received a dental exam for fluorosis. Water, urine, and saliva were analyzed for fluoride content. Questionnaire responses and results of sample analyses were compared and observed differences were analyzed. RESULTS: 83 African American and 109 White children completed the study. Dental fluorosis was observed in 62.5 percent White and 80.1 percent African American children. Significant differences were found for fluorosis prevalence and severity between the groups (P < 0.05). Less African American children reported having used fluoride supplements in the past. White children began brushing their teeth at an earlier age. More White children visited a dentist for the first time before age 3. African American children reported currently using larger amounts of toothpaste. More Whites than African Americans had received topical fluoride treatments over the previous year. All of these differences were significant. Multivariate models showed that supplement use and amount of toothpaste used for brushing had significant associations to a child's fluorosis scores. Fluoride concentration of water and saliva was not different for the two groups; however, the fluoride content in urine was significantly higher in African Americans than in Whites [P < 0.05; 1.40 +/- standard deviation (SD) 0.65 ppm versus 1.08 +/- SD 0.28 ppm]. CONCLUSIONS: Differences in fluoride exposure between two racial groups were observed. These differences are complex and need to be better defined.

Prevalence of molar-incisor hypomineralization and other enamel defects and associated sociodemographic determinants in Indiana.

BACKGROUND: The aim of this study was to determine the prevalence and severity of molar-incisor hypomineralization (MIH) in a cohort of school-aged children in Indiana. METHODS: A calibrated examiner screened eligible school-aged children for MIH and other enamel defects. The authors used the integrated Modified Developmental Defects of Enamel Index and the European Academy of Pediatric Dentistry criteria to examine the permanent first molars, permanent incisors, and primary second molars. The authors used descriptive statistics, exact 95% confidence intervals, and χ2 tests for analysis (α = 5%). RESULTS: A total of 337 participants (mean [standard deviation] age, 9.1 (1.7) years; 52% 6 through 8 years; 66% non-Hispanic white) were examined. The prevalence estimate for MIH was 13% as opposed to a 52% prevalence estimate for any enamel defect (AED) of any of the index teeth. Living in an area with water fluoridation levels greater than 0.7 parts per million or being non-Hispanic black was significantly associated with higher prevalence of AED (P < .05) but not with the prevalence of MIH. Demarcated opacities were the most prevalent defects (43%), followed by atypical restorations (32%). Higher age and higher number of MIH-affected surfaces were associated with larger MIH defect extension (P < .05). CONCLUSIONS: Nearly 1 in 6 children in Indiana had at least 1 permanent first molar with MIH. Water fluoridation levels and race or ethnicity were associated with the prevalence of AED but not with MIH prevalence. PRACTICAL IMPLICATIONS: US dental practitioners should be cognizant that MIH is a common finding. Children with a high number of MIH-affected surfaces would benefit the most from early identification and management as the extension of the defects tends to worsen with age.

U.S. Pediatric Dentists' Perception of Molar Incisor Hypomineralization.

Purpose: The purpose of this survey-based study was to target U.S. pediatric dentists in the Midwest region to determine their knowledge, perceptions, and clinical management strategies of molar incisor hypomineralization (MIH). Methods: After obtaining appropriate authorizations, all pediatric dentists identified by the American Academy of Pediatric Dentistry's 2016 to 2017 membership directory in the 12 Midwest states were invited to take part in the study. The questionnaire, adopted from previous studies, incorporated information of the participants' demographics and educational/clinical backgrounds and MIH-focused questions. Descriptive statistics and chi-square tests were used for analysis. An alpha level less than 0.05 was considered statistically significant. Results: A total of 251 out of 975 surveys were completed (26 percent). Nearly all participants were familiar with MIH. The majority reported the MIH prevalence to be less than 10 percent in their clinical practice (62 percent). Most respondents were either very confident (65 percent) or confident (34 percent) when diagnosing teeth with MIH. The most cited clinical challenge in managing MIH teeth was "long-term success of restorations" (79 percent). When analyzed individually, responses differed significantly for different demographics and educational characteristics of the respondents (P<0.05). Conclusion: MIH is generally well acknowledged by U.S. Midwest pediatric dentists, with differences related to their perceptions of the condition's prevalence as well as clinical and restorative management challenges.

Relationship between enamel fluorosis severity and fluoride content.

OBJECTIVES: Enamel fluorosis is a hypomineralization caused by chronic exposure to high levels of fluoride during tooth development. Previous research on the relationship between enamel fluoride content and fluorosis severity has been equivocal. The current study aimed at comparing visually and histologically assessed fluorosis severity with enamel fluoride content. METHODS: Extracted teeth (n=112) were visually examined using the Thylstrup and Fejerskov Index for fluorosis. Eruption status of each tooth was noted. Teeth were cut into 100 µm slices to assess histological changes with polarized light microscopy. Teeth were categorized as sound, mild, moderate, or severe fluorosis, visually and histologically. They were cut into squares (2 × 2 mm) for the determination of fluoride content (microbiopsy) at depths of 30, 60 and 90 µm from the external surface. RESULTS: Erupted teeth with severe fluorosis had significantly greater mean fluoride content at 30, 60 and 90 µm than sound teeth. Unerupted teeth with mild, moderate and severe fluorosis had significantly greater mean fluoride content than sound teeth at 30 µm; unerupted teeth with mild and severe fluorosis had significantly greater mean fluoride content than sound teeth at 60 µm, while only unerupted teeth severe fluorosis had significantly greater mean fluoride content than sound teeth at 90 µm. CONCLUSIONS: Both erupted and unerupted severely fluorosed teeth presented higher mean enamel fluoride content than sound teeth. CLINICAL SIGNIFICANCE: Data on fluoride content in enamel will further our understanding of its biological characteristics which play a role in the management of hard tissue diseases and conditions.

Fluoride content in plaque solids and fluid after ingestion of fluoridated milk.

This study explored differences in dental biofilm solids and fluid fluoride after ingestion of NaF or Na2FPO3 in milk or non-fluoridated milk. Eighteen volunteers ingested 1 mg fluoride in 200 mL of milk or 200 mL of non-fluoridated milk. Biofilm samples were collected at baseline, 30, 60, and 240 min and biofilm solids and fluid were micro-analyzed for fluoride. Analysis of variance was performed and the total delivery, retention, and clearance of fluoride to biofilm solids and fluid were estimated as the area under the curve between 0 and 240 min. No statistically significant differences were found for baseline values. Biofilm fluid fluoride values ranged from 0.11 ± 0.05 to 0.21 ± 0.08 µg F/mL while biofilm solid values ranged from 0.62 ± 0.39 to 1.75 ± 1.16 µg F/g. Biofilm fluid values were significantly lower at 60 min for Na2FPO3 in milk. Clearance profiles for biofilm fluid diverged after the initial 60 min. Na2FPO3 had a smaller area under the curve from 60 to 240 min than NaF. Results of this study indicate that the release and clearance of fluoride in biofilm vary among fluoridation compounds and that the concentrations in biofilm solids and fluid also vary and are not correlated to each other in many cases.

Fluoride induces endoplasmic reticulum stress in ameloblasts responsible for dental enamel formation.

The mechanism of how fluoride causes fluorosis remains unknown. Exposure to fluoride can inhibit protein synthesis, and this may also occur by agents that cause endoplasmic reticulum (ER) stress. When translated proteins fail to fold properly or become misfolded, ER stress response genes are induced that together comprise the unfolded protein response. Because ameloblasts are responsible for dental enamel formation, we used an ameloblast-derived cell line (LS8) to characterize specific responses to fluoride treatment. LS8 cells were growth-inhibited by as little as 1.9-3.8 ppm fluoride, whereas higher doses induced ER stress and caspase-mediated DNA fragmentation. Growth arrest and DNA damage-inducible proteins (GADD153/CHOP, GADD45alpha), binding protein (BiP/glucose-responsive protein 78 (GRP78), the non-secreted form of carbonic anhydrase VI (CA-VI), and active X-box-binding protein-1 (Xbp-1) were all induced significantly after exposure to 38 ppm fluoride. Unexpectedly, DNA fragmentation increased when GADD153 expression was inhibited by short interfering RNA treatment but remained unaffected by transient GADD153 overexpression. Analysis of control and GADD153(-/-) embryonic fibroblasts demonstrated that caspase-3 mediated the increased DNA fragmentation observed in the GADD153 null cells. We also demonstrate that mouse incisor ameloblasts are sensitive to the toxic effects of high dose fluoride in drinking water. Activated Ire1 initiates an ER stress response pathway, and mouse ameloblasts were shown to express activated Ire1. Ire1 levels appeared induced by fluoride treatment, indicating that ER stress may play a role in dental fluorosis. Low dose fluoride, such as that present in fluoridated drinking water, did not induce ER stress.