Dentin Regeneration

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66570/2/10.1177_08959374950090030501.pd

Randomised study of the effects of fluoride and time on in situ remineralisation of acid-softened enamel

Objectives This single-centre, randomised, crossover study used a short-term in situ dental erosion remineralisation model to explore the remineralisation of acid-softened enamel in the 4-h period immediately following brushing with an anti-erosion, dentin hypersensitivity test dentifrice containing 1150 ppm fluoride (as sodium fluoride [NaF]) or a placebo dentifrice with no fluoride. Materials and methods Fifty participants wearing a palatal appliance holding surface-softened bovine enamel specimens brushed their natural teeth with their assigned dentifrice. Specimens were removed at 5-, 10-, 15-, 30-, 60-, 120- and 240-min post brushing. Enamel remineralisation effect was evaluated at each timepoint by percent surface microhardness recovery (%SMHR) and enamel fluoride uptake (EFU). After a second in vitro erosive challenge, the percent relative erosion resistance (%RER) was calculated. Results Statistically significant differences in %SMHR were observed for the test dentifrice compared with the placebo dentifrice from the 60-min timepoint onwards (all p < 0.02; mean difference of 8.66 [95% CI 3.46, 13.87] at 60 min). At each specimen removal time, %RER and EFU were statistically significantly higher for the test dentifrice compared with the placebo dentifrice (p < 0.0001 for all). No treatment-related or serious adverse events were reported. Conclusions The NaF-containing anti-erosion, dentin hypersensitivity dentifrice improved remineralisation of acid-softened enamel starting at 60 min of intra-oral exposure. It also improved enamel erosion resistance and fluoride uptake as early as 5 min after exposure to fluoridated dentifrice slurry

Comparison of Cell Sediment and Surface Grown Test Plaque Using Scanning Electron Microscopy

Scanning electron microscopy was used to compare the morphology, integrity and distribution of bacterial cells in a test plaque grown on the surface of enamel with that of the cell sediment plaque routinely used in a short-term intraoral caries model. Cultures of S. mutans IB-1600 or S. sobrinus 6715-13 were grown in complex media supplemented with either 2.0% sucrose (glucan plaque) or 0.2 % glucose (non-glucan plaque). Cell sediment (CS) plaque was prepared by centrifuging the cultures after incubation, recovering the cell sediment, and spreading it on Metricel membrane filter paper. Surface grown (SG) plaque was prepared by suspending saliva-coated bovine enamel in the culture inedium, incubating, and recovering the enamel assembly with bacterial accumulations. Cell morphology and integrity, as well as the appearance of glucan-like material produced by the cells, was similar in both CS and SG test plaques. The cell distribution however, varied in the SG plaque from extremes of all cells to all glucan, whereas the cell sediment plaque was more uniform in cell distribution. A highly standardized test plaque minimizes variability in the intraoral caries model. These findings support the contention that the bacterial cells in a cell sediment plaque are similar in morphology, integrity and glucan production to surface grown plaque, and have the added advantage of uniform distribution, which makes the cell sediment plaque more appropriate for intraoral caries model studies

A Potential Biofilm Metabolite Signature for Caries Activity - A Pilot Clinical Study

BACKGROUND: This study's aim was to compare the dental biofilm metabolite-profile of caries-active (N=11) or caries-free (N=4) children by gas chromatography-mass spectrometry (GC/MS) analyses. METHODS: Samples collected after overnight fasting, with or without a previous glucose rinse, were combined for each child based on the caries status of the site, re-suspended in ethanol and analyzed by GC/MS. RESULTS: Biofilm from caries-active sites exhibited a different chromatographic profile compared to caries-free sites. Qualitative and quantitative analysis suggested a special cluster of branched alcohols and esters present at substantially higher intensity in biofilms of caries-active sites. CONCLUSIONS: This pilot study indicates that there are metabolites present in the biofilm which have the potential to provide a characteristic metabolomics signature for caries activity

Topical Ferumoxytol Nanoparticles Disrupt Biofilms and Prevent Tooth Decay in Vivo Via Intrinsic Catalytic Activity

Ferumoxytol is a nanoparticle formulation approved by the U.S. Food and Drug Administration for systemic use to treat iron deficiency. Here, we show that, in addition, ferumoxytol disrupts intractable oral biofilms and prevents tooth decay (dental caries) via intrinsic peroxidase-like activity. Ferumoxytol binds within the biofilm ultrastructure and generates free radicals from hydrogen peroxide (H2O2), causing in situ bacterial death via cell membrane disruption and extracellular polymeric substances matrix degradation. In combination with low concentrations of H2O2, ferumoxytol inhibits biofilm accumulation on natural teeth in a human-derived ex vivo biofilm model, and prevents acid damage of the mineralized tissue. Topical oral treatment with ferumoxytol and H2O2 suppresses the development of dental caries in vivo, preventing the onset of severe tooth decay (cavities) in a rodent model of the disease. Microbiome and histological analyses show no adverse effects on oral microbiota diversity, and gingival and mucosal tissues. Our results reveal a new biomedical application for ferumoxytol as topical treatment of a prevalent and costly biofilm-induced oral disease

Children living with ‘sustainable’ urban architectures

This paper considers the everyday geographies of children living in new large-scale urban developments in which multiple forms of ‘sustainable’ urban architecture are characteristic features. We argue that children’s experiences of living with materialities, politics and technologies of sustainability have too-often been marginalised in much chief research on childhood, youth and sustainability. Drawing on qualitative research with 8-16-year-olds living with materialities of ‘sustainable’ eco-housing, urban drainage, wind turbines and photovoltaic panelling, we explore how sustainable urban architectures are noticed, (mis)understood, cared about, and lived-with by children in the course of their everyday geographies. In so doing, we highlight the challenging prevalence and significance of architectural conservatisms, misconceptions, rumours disillusionments and urban myths relating to sustainable urban architectures

The distribution of burden of dental caries in schoolchildren: a critique of the high-risk caries prevention strategy for populations

BACKGROUND: The 'high-risk approach' is a commonly adopted strategy recommended for the prevention of dental caries in populations. The scientific basis for the strategy has been questioned. The objective of this study is to assess the contribution that children identified at 'high-risk' made towards the total of new caries lesions over a 4-year period, by analysing the distribution of new lesions per 100 children. METHODS: Data are from the National Preventive Dentistry Demonstration Programme (NPDDP) in the United States. The analyses identified the distribution of new carious lesions over a 4-year period in four groups of 7 year-old children who received differing preventive regimes. RESULTS: The majority of new lesions occurred in those children classified at lowest caries risk at baseline. Irrespective of the preventive regime adopted and the initial caries levels, children classified as 'highest risk' contributed less than 6% of the total number of new lesions developing over 4 years. CONCLUSION: These findings challenge the basis for the adoption of a high-risk strategy

Laser-induced breakdown spectroscopy: a tool for real-time, in vitro and in vivo identification of carious teeth

BACKGROUND: Laser Induced Breakdown Spectroscopy (LIBS) can be used to measure trace element concentrations in solids, liquids and gases, with spatial resolution and absolute quantifaction being feasible, down to parts-per-million concentration levels. Some applications of LIBS do not necessarily require exact, quantitative measurements. These include applications in dentistry, which are of a more "identify-and-sort" nature – e.g. identification of teeth affected by caries. METHODS: A one-fibre light delivery / collection assembly for LIBS analysis was used, which in principle lends itself for routine in vitro / in vivo applications in a dental practice. A number of evaluation algorithms for LIBS data can be used to assess the similarity of a spectrum, measured at specific sample locations, with a training set of reference spectra. Here, the description has been restricted to one pattern recognition algorithm, namely the so-called Mahalanobis Distance method. RESULTS: The plasma created when the laser pulse ablates the sample (in vitro / in vivo), was spectrally analysed. We demonstrated that, using the Mahalanobis Distance pattern recognition algorithm, we could unambiguously determine the identity of an "unknown" tooth sample in real time. Based on single spectra obtained from the sample, the transition from caries-affected to healthy tooth material could be distinguished, with high spatial resolution. CONCLUSIONS: The combination of LIBS and pattern recognition algorithms provides a potentially useful tool for dentists for fast material identification problems, such as for example the precise control of the laser drilling / cleaning process

Dentifrices, mouthwashes, and remineralization/caries arrestment strategies

While our knowledge of the dental caries process and its prevention has greatly advanced over the past fifty years, it is fair to state that the management of this disease at the level of the individual patient remains largely empirical. Recommendations for fluoride use by patients at different levels of caries risk are mainly based on the adage that more is better. There is a general understanding that the fluoride compound, concentration, frequency of use, duration of exposure, and method of delivery can influence fluoride efficacy. Two important factors are (1) the initial interaction of relatively high concentrations of fluoride with the tooth surface and plaque during application and (2) the retention of fluoride in oral fluids after application

Children's unique experience of depression: Using a developmental approach to predict variation in symptomatology

<p>Abstract</p> <p>Background</p> <p>Current clinical knowledge suggests that children can have different types of depressive symptoms (irritability and aggression), but presents no theoretical basis for these differences. Using a developmental approach, the present study sought to test the relationship between developmental level (mental age) and expression of depressive symptoms. The primary hypothesis was that as children's mental age increased, so would the number of internalizing symptoms present.</p> <p>Methods</p> <p>Participants were 252 psychiatric inpatients aged 4 to 16 with a diagnosed depressive disorder. All children were diagnosed by trained clinicians using DSM criteria. Patients were predominantly male (61%) with varied ethnic backgrounds (Caucasian 54%; African American 22%; Hispanic 19%; Other 5%). Children were given an IQ test (KBIT or WISC) while within the hospital. Mental age was calculated by using the child's IQ score and chronological age. Four trained raters reviewed children's records for depressive symptoms as defined by the DSM-IV TR. Additionally, a ratio score was calculated to indicate the number of internalizing symptoms to total symptoms.</p> <p>Results</p> <p>Mental age positively correlated (<it>r </it>= .51) with an internalizing total symptom ratio score and delineated between several individual symptoms. Mental age also predicted comorbidity with anxiety and conduct disorders. Children of a low mental age were more likely to be comorbid with conduct disorders, whereas children with a higher mental age presented more often with anxiety disorders. Gender was independently related to depressive symptoms, but minority status interacted with mental age.</p> <p>Conclusion</p> <p>The results of this study indicate that a developmental approach is useful in understanding children's depressive symptoms and has implications for both diagnosis and treatment of depression. If children experience depression differently, it follows that treatment options may also differ from that which is effective in adults.</p