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    ABSTRACT: The mechanistic action of fluoride on inhibition of enamel demineralization was investigated using (19)F magic angle spinning nuclear magnetic resonance (MAS-NMR). The aim of this study was to monitor the fluoride-mineral phase formed on the enamel as a function of the concentration of fluoride ions [F(-)] in the demineralizing medium. The secondary aim was to investigate fluorapatite formation on enamel in the mechanism of fluoride anti-caries efficacy. Enamel blocks were immersed into demineralization solutions of 0.1 M acetic acid (pH 4) with increasing concentrations of fluoride up to 2,262 ppm. At and below 45 ppm [F(-)] in the solution, (19)F MAS-NMR showed fluoride-substituted apatite formation, and above 45 ppm, calcium fluoride (CaF2) formed in increasing proportions. Further increases in [F(-)] caused no further reduction in demineralization, but increased the proportion of CaF2 formed. Additionally, the combined effect of strontium and fluoride on enamel demineralization was also investigated using (19)F MAS-NMR. The presence of 43 ppm [Sr(2+)] in addition to 45 ppm [F(-)] increases the fraction of fluoride-substituted apatite, but delays formation of CaF2 when compared to the demineralization of enamel in fluoride-only solution.
    Caries Research 05/2013; 47(5):421-428.
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    ABSTRACT: Background/Aims: Mechanical removal of carious dentine based on perceived hardness is subjective and tends to be excessively destructive; chemo-mechanical techniques have been proposed as being more objective and conservative. The aims of the present study are to use X-ray microtomography (XMT/micro-CT) to determine the three-dimensional mineral concentration distribution in sound, carious and excavated dentine using hand excavation (HE) and a chemo-mechanical, Carisolv (CS), removal technique for primary molars, and to compare the volume of sound dentine removed in order to validate the efficacies of these two techniques. Methods: Twenty-one primary molars with open carious cavities were hemisected. The carious tissue in one half was then removed by HE and the other by CS. XMT scans were taken before and after caries removal. After alignment, subtracted XMT images from the two scans revealing the tissues removed were generated, from which mineral distributions were determined, and volumes of sound dentine removed by each technique were calculated. Results: It was found that the sound dentine removed by HE and CS techniques accounted for 4.0 and 2.1% of total tissues removed, respectively. The mean cut-off linear attenuation coefficients at 40 keV to which HE and CS excavated to were 1.27 and 1.09 cm(-1), respectively. The corresponding Knoop hardness number for the cut-off for CS was 25 kg·mm(-2). Conclusion: It is concluded that using XMT, CS is validated to be more conservative than HE and preserves a layer of partially demineralised dentine with a mineral concentration >0.97 g·cm(-3).
    Caries Research 08/2012; 46(6):561-567.
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    ABSTRACT: Enamel demineralization is slowed by salivary proteins that inhibit calcium hydroxyapatite (HA) demineralization. Statherin (StN43), a 43-residue phosphorylated salivary protein with primary sequence similarities to osteopontin and caseins, binds calcium and HA. The aim of this study was to identify the minimum length of the functional domain of the statherin molecule required for cariostatic function by measuring the efficacy of peptides of progressively shorter length (i.e. containing only the N-terminal 21 (StN21), 15 (StN15), 10 (StN10), or 5 (StN5) residues) to reduce HA demineralization rates (RD(HA) ). Porous HA blocks were used as enamel analogues, and were exposed to 0.1 M acetic acid at pH 4 for 120 h, rinsed, and treated with StN21, StN15, StN10, or StN5 peptides (1.88 × 10(-5) M) for 24 h, then demineralized for a further 120 h. The RD(HA) was measured, before and after peptide treatment, using scanning microradiography. Hydroxyapatite blocks treated with StN21 and StN15 demonstrated a 50-60% reduction in the RD(HA) . However, no reduction in the RD(HA) was observed following treatment with either StN10, StN5, or buffer only. The mechanism by which statherin-like peptides reduce RD(HA) may be associated with their binding to HA surfaces. Comparisons with previously published binding energies of statherin to HA also suggest that statherin-like peptides containing 15 N-terminal residues or more, are required for binding, suggesting a link between binding and demineralization reduction.
    European Journal Of Oral Sciences 12/2011; 119 Suppl 1:13-8.
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    ABSTRACT: This paper is part of a series of papers towards a European Core Curriculum in Cariology for undergraduate dental students. The European Core Curriculum in Cariology is the outcome of a joint workshop of the European Organization for Caries Research (ORCA) together with the Association for Dental Education in Europe (ADEE), which was held in Berlin from 27 to 30 June 2010. This paper presents a closer look at the knowledge base as presented in the European Core Curriculum in Cariology. It comprises not only traditional basic sciences, such as anatomy and histology, but also emerging sciences such as molecular biology and nanotechnology and also fields such as behavioural sciences and research methodology. The different supporting competences are elaborated and explained. The problems of implementing a curriculum that truly integrates this foundation knowledge into the clinical teaching are discussed.
    European Journal Of Dental Education 11/2011; 15 Suppl 1:18-22.
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    ABSTRACT: This was to use x-ray microtomography (XMT), to assess the mineral composition and 3-D structure of enamel and bone in the teeth and skulls of diabetic rodents. Three-dimensional images of the skull were reconstructed using computer generated false colour to highlight different levels of mineralization in bone and enamel. These showed that diabetic rodents exhibited more wear in their teeth. Deformities were observed in the alveolar process of the mandible and maxilla. Regions of extensive hypomineralization were found in the calvarial bone of skulls. The maximum mineral concentrations and the time constants for diabetic rodents were similar to the controls. The diabetic mice appeared to have random regions of hypomineralization and one diabetic rat had areas of hypoplasia in the mandibular incisors. Diabetes may have a detrimental influence on the function of ameloblasts in laying down enamel.
    European Archives of Paediatric Dentistry. Official Journal of the European Academy of Paediatric Dentistry. 01/2008; 8(4):195-200.
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    ABSTRACT: The aim of this study was to show the morphology of the carious lesion in dentine in three dimensions (3D). A novel high-definition X-ray microtomography (XMT) scanner was used to scan 10 carious primary molars at a resolution of 15 x 15 x 15 microm3. A stack of approximately 640 XMT slices were recorded for each tooth. Using this data set and a volume rendering algorithm, each tooth was reconstructed in 3D. The VG Studio Max 1.0 visualization software package was used to make normal enamel and dentine transparent to show the carious lesions in 3D. A video film, comprised of the rendered images from 60 viewing angles rotating through 360 degrees , was produced to show the carious lesion and its relation to the pulp in a three-dimensional perspective (http://www.smd.qmul.ac.uk/dental/oralgrowdev/biophysics/xmt/images/carious.mpg). These images showed that carious lesions in dentine were bowl-shaped. The pulp adjacent to the carious lesion was also observed to mimic the base of the bowl-shaped lesion. It was concluded from the teeth studied that the shape at the base of the carious lesion in dentine is curved in 3D, rather than conical, as traditionally believed from two-dimensional image interpretation. Further 3D studies are needed to investigate whether the bowl-shaped carious lesions in dentine also apply to caries in other types of teeth.
    International Journal of Paediatric Dentistry 12/2006; 16(6):419-23.
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    ABSTRACT: To examine the accuracy and precision of the Steiner prediction cephalometric analysis. The sample consisted of 275 randomly selected patients, treated between 1970 and 1995 at a university department. Lateral cephalograms before (T1) and after orthodontic treatment (T2) were analyzed using the Steiner analysis. A prediction of the final outcome at T2 for the variables ANB degrees, U1 to NA mm, L1 to NB mm, and Pg to NB mm was performed at T1. The difference between the actual outcome at T2 and the Steiner predicted value (SPV), which was done at T1, was calculated. Accuracy (mean difference between T2 and SPV) and precision (standard deviation of the mean prediction discrepancies) of the prediction were studied. Paired t-test was used to detect under- or overestimation of the predicted values. The mean decrease in angle ANB was 1.4 +/- 2.7 degrees and for U1 to NA 2.0 +/- 2.6 mm, while L1 to NB increased 0.8 +/- 2.0 mm and Pg to NB 0.7 +/- 1.1 mm. The predicted values for the changes in ANB angle, the distance of upper incisor U1 to NA as well as the distance Pg to NB were significantly overestimated when compared with the actual outcome, while the change in the distance of lower incisor L1 to NB was underestimated. The prediction of cephalometric treatment outcome as used in the Steiner analysis is not accurate enough to base orthodontic treatment decisions upon.
    Orthodontics and Craniofacial Research 06/2006; 9(2):77-83.
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    ABSTRACT: Cone-beam reconstruction from projections with a circular source locus (relative to the specimen) is commonly used in X-ray microtomography systems. Although this method does not provide an “exact” reconstruction, since there is insufficient data in the projections, the approximation is considered adequate for many purposes. However, some specimens, with sharp changes in X-ray attenuation in the direction of the rotation axis, are particularly prone to cone-beam-related errors. These errors can be reduced by increasing the source-to-specimen distance, but at the expense of reduced signal-to-noise ratio or increased scanning time. An alternative method, based on heuristic arguments, is to scan the specimen with both short and long source-to-specimen distances and combine high frequency components from the former reconstruction with low frequency ones from the latter. This composite reconstruction has the low noise characteristics of the short source-to-specimen reconstruction and the low cone-beam errors of the long one. This has been tested with simulated data representing a particularly error prone specimen.
    Nuclear Instruments and Methods in Physics Research Section A Accelerators Spectrometers Detectors and Associated Equipment 01/2005;
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    ABSTRACT: To determine the mineral concentration distribution in deciduous enamel by quantitative X-ray microtomography (XMT). Tooth rods ( approximately 2 mm x 2 mm) were removed from the mid-buccal region of 11 deciduous molars. Three XMT slices were taken at 1.5, 2.0 and 2.5 mm from the amelocemental junction. The distribution and variation in mineral concentration of enamel were studied from the XMT images. The mean mineral concentration for all the teeth was 2.81 (S.D. = 0.065) g cm(-3). There was no notable difference in the mean mineral concentration values between the three XMT slices of each tooth. However, there was up to 8% variation between different teeth (2.69-2.92 g cm(-3)). Gradients of increasing mineral concentration from the amelodentinal junction (ADJ) to the external surface were found, ranging from 0.08 to 0.60 mg cm(-3) microm(-1) with a mean of 0.366 mg cm(-3) microm(-1). The mineral concentration gradients in the occlusal slices were steeper than those in the cervical slices. The difference in mineral concentration between the inner and outer enamel ranged from 1.5 to 8.7%. In view of the large variation in both the means and the gradients of mineral concentration in deciduous molars, the mineral distribution of each experimental tooth should be measured as baseline data in studies of caries progression.
    Archives of Oral Biology 12/2004; 49(11):937-44.
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    ABSTRACT: The aim was to estimate the total cost, including the direct costs (outpatient costs) and indirect costs (missed working day) of treating children and adolescents with traumatic injuries to their incisors. Factors such as the number of treatment visits and the success of outcome were also investigated. The sample was taken from patients who attended the dental trauma clinic at a London teaching hospital between 1990 and 2001. Eighty-one patients, with 111 traumatized incisors were included in this study. The mean age was 9.9 (SD = 2.33) years and the male:female ratio was 3:2. The median number of visits and median treatment duration were eight visits and 21 months, respectively. Sixty-two per cent of the patients lived >5 miles and 25% lived >10 miles from the hospital; 44% of the patients had uncomplicated and 56% had complicated trauma to their incisors. Accidental falls, falls involving a second person, sport-related injuries and road accidents accounted for 30, 22, 22 and 17% of the total injuries. For uncomplicated trauma, 97% of the patients had a successful outcome but this was reduced to 58% for complicated trauma. The average total cost of treating a patient with one traumatic injury was 856 pounds. The best predictor for higher number of visits and unsuccessful outcome was complicated trauma with odd ratios of 4.5 and 24 (95% CI 1.5-13.7 and 2.9-194.2), respectively. It was concluded that the indirect cost was a considerably large proportion (39%) of the total cost. More specialists in paediatric dentistry are needed to improve access to care locally and thus reducing the indirect travelling cost.
    Dental Traumatology 12/2004; 20(6):327-33.
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