N X West

Worldwide Clinical Trials, Nottigham, England, United Kingdom

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Publications (51)91.12 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: Research on dental erosion has largely been undertaken at room temperature despite fruit juice drinks often being consumed at elevated temperatures in the United Kingdom, notably during periods of convalesce. The aim of the study was to evaluate the erosive potential of two fruit juices containing acidic non-alcoholic drinks at elevated temperatures in situ on human enamel after 5, 10 and 15 days. A commercially available conventional apple and blackcurrant fruit juice drink was compared to a blackcurrant juice drink modified to have low erosive potential, and mineral water consumed at approximately 59 °C. Twenty-one healthy volunteers aged 18 or over participated in a single-centre, single-blind (blinded to the investigator), three-treatment crossover study. Subjects were randomised to a treatment sequence using a Latin square design. Subjects wore upper removable appliances containing one human enamel specimen from 9 am to 5 pm for 15 days for each beverage. Measurements of enamel loss were recorded after 5, 10 and 15 days by contact surface profilometry. The low erosive blackcurrant drink caused significantly less enamel loss (P < 0·05) than the commercially available conventional apple and blackcurrant fruit juice drink and was not statistically significantly different to mineral water at any of the time points in the study. Consuming the modified low erosive blackcurrant drink at an elevated temperature resulted in negligible enamel loss in situ, consistent with room temperature findings. © 2015 John Wiley & Sons Ltd.
    Journal of Oral Rehabilitation 03/2015; DOI:10.1111/joor.12285 · 1.93 Impact Factor
  • Nicola West, Joon Seong, Maria Davies
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    ABSTRACT: Dentine hypersensitivity is a common oral pain condition affecting many individuals. The aetiology is multifactorial; however, over recent years the importance of erosion has become more evident. For dentine hypersensitivity to occur, the lesion must first be localised on the tooth surface and then initiated to exposed dentine tubules which are patent to the pulp. The short, sharp pain symptom is thought to be derived from the hydrodynamic pain theory and, although transient, is arresting, affecting quality of life. This episodic pain condition is likely to become a more frequent dental complaint in the future due to the increase in longevity of the dentition and the rise in tooth wear, particularly amongst young adults. Many efficacious treatment regimens are now available, in particular a number of over-the-counter home use products. The basic principles of treatment are altering fluid flow in the dentinal tubules with tubule occlusion or modifying or chemically blocking the pulpal nerve. © 2014 S. Karger AG, Basel.
    Monographs in oral science 01/2014; 25:108-122. DOI:10.1159/000360749
  • M Addy, N X West
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    ABSTRACT: Dentine hypersensitivity (DH) is a common, painful dental condition with a multi-factorial aetiology. The hydrodynamic mechanism theory to explain dentine sensitivity also appears to fit DH: lesions exhibiting large numbers of open dentinal tubules at the surface and patent to the pulp. By definition, DH can only occur when dentine becomes exposed (lesion localisation) and tubules opened (lesion initiation), thus permitting increased fluid flow in tubules on stimulation. Erosion, particularly from dietary acids appears to play a dominant role in both processes. Toothbrushing with most toothpaste products alone cause clinically insignificant wear of enamel but are additive, even synergistic, to erosive enamel loss. Additionally, toothbrushing with toothpaste is implicated in 'healthy' gingival recession. Toothbrushing with most toothpastes removes the smear layer to expose tubules and again can exacerbate erosive loss of dentine. These findings thereby implicate toothbrushing with toothpaste in the aetiology of DH. Management of the condition should have secondary prevention at the core of treatment and therefore, must consider first and foremost the aetiology. Fluoride toothpaste at present appears to provide little primary or secondary preventive benefits to DH; additional ingredients can provide therapeutic benefits. Potassium-based products to block pulpal nerve response have caused much debate and are considered by many as unproven, which should not translate to ineffective. Several toothpaste technologies formulated to block tubules are from studies in vitro, in situ and controlled clinical trials considered proven for the treatment of DH.
    Monographs in oral science 01/2013; 23:75-87. DOI:10.1159/000350477
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    N X West, A Lussi, J Seong, E Hellwig
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    ABSTRACT: OBJECTIVES: The paper's aim is to review dentin hypersensitivity (DHS), discussing pain mechanisms and aetiology. MATERIALS AND METHODS: Literature was reviewed using search engines with MESH terms, DH pain mechanisms and aetiology (including abrasion, erosion and periodontal disease). RESULTS: The many hypotheses proposed for DHS attest to our lack of knowledge in understanding neurophysiologic mechanisms, the most widely accepted being the hydrodynamic theory. Dentin tubules must be patent from the oral environment to the pulp. Dentin exposure, usually at the cervical margin, is due to a variety of processes involving gingival recession or loss of enamel, predisposing factors being periodontal disease and treatment, limited alveolar bone, thin biotype, erosion and abrasion. CONCLUSIONS: The current pain mechanism of DHS is thought to be the hydrodynamic theory. The initiation and progression of DHS are influenced by characteristics of the teeth and periodontium as well as the oral environment and external influences. Risk factors are numerous often acting synergistically and always influenced by individual susceptibility. CLINICAL RELEVANCE: Whilst the pain mechanism of DHS is not well understood, clinicians need to be mindful of the aetiology and risk factors in order to manage patients' pain and expectations and prevent further dentin exposure with subsequent sensitivity.
    Clinical Oral Investigations 12/2012; 17(Suppl 1). DOI:10.1007/s00784-012-0887-x · 2.29 Impact Factor
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    ABSTRACT: OBJECTIVES: The aim of the study was to determine in situ the relative abilities of two desensitising toothpastes to occlude dentinal tubules with or without acid challenge. MATERIALS AND METHODS: The study design was a single centre, randomised, split mouth crossover model examining four treatments over two periods. The primary outcome was the degree of occlusion proffered by two desensitising toothpastes [Sensodyne(®) Rapid Relief (8% strontium acetate, 1040 ppm sodium fluoride) and Colgate(®) Sensitive Pro-Relief(TM) daily (8% arginine, 1450 ppm sodium monofluorophosphate)], a standard toothpaste (1450 ppm sodium fluoride) and water, after acid challenge. Healthy adult volunteers wore bi-lateral lower buccal appliances each with two dentine sections, receiving two treatments per study period. Samples were brushed twice a day with treatment, with two additional 3-min extra-oral acidic challenges applied ex vivo on days 3 and 4. A secondary outcome was the degree of occlusion attained in the absence of acid challenge. Examiners blinded to the study assessed occlusion by visual score of post-treatment scanning electron microscope images. RESULTS: All 28 participants completed the study. In the absence of acid challenge, occlusion scores for both desensitising toothpastes were similar and significantly better than control scores (p < 0.02). After acid challenge both desensitising toothpastes occluded more effectively than controls; however, occlusion scores for the strontium acetate paste were significantly greater than those of the arginine paste (p < 0.02). CONCLUSIONS: The occluding properties of the strontium acetate toothpaste were significantly more robust after acid challenge than those of the arginine toothpaste. CLINICAL RELEVANCE: Patients with hypersensitivity, regularly imbibing dietary acidic drinks, should be advised that Sensodyne(®) Rapid Relief provides robust tubule occlusion despite repeated acidic challenges.
    Clinical Oral Investigations 02/2012; 17(1). DOI:10.1007/s00784-012-0683-7 · 2.29 Impact Factor
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    ABSTRACT: To determine if brushing dentine with 2 moderate RDA desensitising toothpastes, results in a significant dentine wear difference and whether this difference continues to be relevant when preceded with an erosive challenge. An in situ, single centre, single blind, randomised, split mouth study, evaluated the difference in abrasion of 2 toothpastes (SFM - Sensodyne Fresh Mint(®) RDA 70; CPHM - Crest Pro-Health Clean Mint(®) RDA 120) in 28 healthy volunteers. Two toothpaste treatments were administered 3×/day, for each of the two 15 day periods, subjects wearing bi-lateral, lower buccal appliances each with 4 dentine sections. A 2 min extra-oral acidic challenge preceded toothbrushing for 2 study arms. Contact profilometry measured samples at baseline, days 5, 10 and 15. Brushing with SFM was significantly less abrasive than brushing with CPHM at all time points, with or without a preceding acidic challenge (p<0.0001). The additional dentine loss arising from the erosive challenge prior to brushing with each paste was linear with time and independent of abrasive effect. The desensiting toothpastes' RDA, directly related to dentine loss with toothbrushing. An acidic challenge prior to brushing did not negate the benefits of reduced wear from the lower RDA paste compared to the higher RDA paste. When brushing eroded dentine, the additional wear appeared independent of abrasive effect. Dentine hypersensitivity sufferers should be recommended to use a low-moderate RDA toothpaste, not to brush more than 2×/day and not immediately following an acidic challenge.
    Journal of dentistry 10/2011; 40(1):77-85. DOI:10.1016/j.jdent.2011.10.010 · 2.84 Impact Factor
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    ABSTRACT: Objectives: Glass ionomer cements (GICs) are frequently used to restore cavities associated with erosive wear. Unfortunately GICs are themselves prone to acid-mediated dissolution. This effectively means that the very materials used to restore erosive tooth wear are themselves prone to erosion. The aim of this study was to compare the acid-mediated wear of four GICs and enamel as a function of temperature over the range 4-60C. Methods: 32 specimens of Ketac Molar, ChemFil Molar, Fuji IX Extra and Diamond Carve GICs were prepared according to manufacturers' instructions and packed into silicone molds set against a glass slab to provide a flat surface with an intervening sheet of acetate to prevent the GIC from adhering to the glass. 32 specimens of bovine enamel were sectioned, mounted in resin and polished using silicon carbide paper to 1200 grit to create a flat surface. Control areas were masked with adhesive tape and specimens were exposed to 0.3% pH3.2 citric acid monohydrate at 4, 25, 37 or 60C, stirred at 0.25m/s for 60min. Wear was recorded using an optical profilometer (Proscan 2000, Scantron). Results: All specimens exhibited statistically significant wear at all temperatures. Wear significantly increased with temperature for all GICs and enamel. Enamel exhibited more wear than any of the GICs at all temperatures, by a factor of 2-6x. There were few statistically significant differences between the different GICs. Conclusions: GICs are prone to acid-mediated dissolution and this process is more rapid at elevated temperatures. None of the GICs investigated had any clear advantage over any other in this regard. Although GIC wear proceeds more slowly than that of enamel, dentists and patients ought to be aware that GICs used to repair erosive lesions are prone to erosion themselves, and that the destruction of the GIC is more rapid in warm solutions.
    British Society for Oral and Dental Research 2011; 09/2011
  • J. MATHARU, S.B. JONES, N.X. WEST
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    ABSTRACT: Objectives: It is understood that tooth sensitivity is due to fluid movement in patent dentinal tubules. Dentine hypersensitivity may be reduced by oral care products which occlude the tubules. The aim of this study was to compare tubular occlusion before and after treatment with conventional and desensitizing dentifrices in vitro using a scanning electron microscope (SEM). Method: Human dentine specimens were obtained in accordance with HTA guidelines and were sterilised, sectioned and mounted in resin. The specimens were polished using alumina to a final grit size of 0.3 m and ultrasonicated in deionised water for 1 min. The smear layer was removed using 10 % citric acid for 10 s. Specimens were treated by rubbing slurry of whole human saliva and dentifrice (Colgate Cavity Protection, Colgate Pro Relief or Sensodyne Rapid) on to the surface using an index finger for 1 min and rinsed with deionised water. Specimens were then exposed to 0.3% citric acid pH 3.2 for 2 min and imaged once more. Specimens were imaged after smear layer removal, after dentifrice treatment and after acid exposure, without coating, using a Phenom G2 Pro benchtop SEM in pseudo-environmental mode using a charge reduction sample holder. Results: Colgate Cavity Protection did not cause tubule occlusion. Treatment with both desensitizing dentifrices resulted in tubule occlusion. There was still some evidence of tubular occlusion for both desensitizing pastes following treatment with citric acid solution. Conclusion: This study was facilitated by the use of a benchtop SEM which can operate in pseudo-environmental mode, allowing imaging of the same specimen at each stage of this study. This provided greater assurance of the level of tubule occlusion caused by the desensitizing pastes when compared to using conventional SEM where the specimen preparation is destructive, meaning that specimens cannot be imaged multiple times.
    British Society for Oral and Dental Research 2011; 09/2011
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    ABSTRACT: The primary objective was to determine the erosive effect of expectorated saliva, following chewing acidic gum, on enamel and dentine samples, using a non-acidic gum as a negative control. Secondary objectives were to determine the effect of brushing enamel and dentine samples and the effect of individual saliva pH and buffering. A single-centre, single-blind, placebo-controlled, two-way crossover study. A clinical trial, involving healthy participants, undertaken at Bristol Dental School and Hospital. Methods: Eight healthy participants expectorated saliva onto prepared enamel and dentine samples while chewing gum (strawberry flavoured acidic gum [active] or peppermint flavoured non-acidic gum [control]). Half of the enamel and dentine samples were brushed before measurement by contact profilometry. Mean enamel and dentine erosion, with and without brushing and the relationship to salivary buffering.Results At 10 days, mean depth of surface loss from dentine samples (95% CI), following chewing of acid-containing gum and subsequent brushing, was -11.34 μm (2.22 μm) and from un-brushed dentine samples was -11.02 μm (1.71 μm). No significant erosion was noted for other groups. Frequent chewers of acid-containing gums are susceptible to dentine erosion even in the presence of good salivary buffering. Enamel erosion was insignificant within the time constraints of the present study but warrants further investigation.
    British dental journal official journal of the British Dental Association: BDJ online 02/2011; 210(3):E3. DOI:10.1038/sj.bdj.2011.51 · 1.08 Impact Factor
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    ABSTRACT: To compare the ability of two new desensitizing toothpaste technologies (one a 5% NovaMin-based toothpaste and the other an 8% arginine-based toothpaste) to occlude patent dentin tubules in a clinical environment relative to a negative control of water and a control toothpaste after four days of twice-daily brushing and dietary acidic challenges. The study design was a single-center, single-blind, randomized, split-mouth, four-treatment, two-period, crossover, in situ clinical study. Healthy subjects wore two lower intra-oral appliances, retaining four dentin samples for four treatment days for each period of the clinical study. Samples were brushed twice daily with a test product (days 1-4), with an additional acidic challenge introduced on two selective days. Scanning electron microscopy (SEM) images were taken of the dentin surface, and dentinal tubule occlusion assessed using a categorical scale. The results demonstrated that the 5% NovaMin toothpaste was statistically superior at occluding patent dentin tubules compared to water (p = 0.009) and the control toothpaste (p = 0.02) at day 4. In contrast, the treatment effect resulting from the 8% arginine toothpaste did not demonstrate the same degree of occlusive propensity, showing no significant difference to the water and control toothpaste at the day 4 time point. Application of the 5% NovaMin toothpaste to dentin showed better dentin tubule occlusion and retention abilities in an oral environment under dietary acid challenge conditions, more so than the 8% arginine toothpaste technology. Given modern dietary habits and practices, these results highlight differences in the acid resistance properties of occlusion technologies, and a potential impact on clinical performance.
    The Journal of clinical dentistry 01/2011; 22(3):82-9.
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    N X West, M Davies, B T Amaechi
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    ABSTRACT: Because of the difficulties in measuring erosion in vivo, a number of in vitro and in situ models have been developed and validated. These models are flexible and informative, allowing single as well as multiple variables to be examined under specific conditions using accurate measurement techniques over defined timelines, thus yielding useful data without harmful effects on individuals. This information, together with clinical findings, is essential for clinicians advising susceptible patients appropriately regarding the management of their condition. Little guidance is available, however, on the standardisation of in vitro and in situ protocols for erosive tooth wear studies, so it is difficult to make meaningful comparisons between investigations as experimental variables differ widely from study to study. The aim of this review was to collate the available data on models designed to assess erosive challenges which are severe enough to cause tissue loss as opposed to just softening of the surface structure. The different types of models, with their merits and pitfalls, are documented. Test substrates, disinfecting regimens and ethical considerations are discussed. The aims of this paper are to give guidance to the researcher on evidence-based in vitro and in situ erosive tooth wear methodology and to suggest best practice given current knowledge.
    Caries Research 01/2011; 45 Suppl 1:43-52. DOI:10.1159/000325945 · 2.50 Impact Factor
  • A. CURTIS, B. SU, N.X. WEST
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    ABSTRACT: Objectives: Dentine hypersensitivity arises when dentine tubules are exposed to external stimuli (thermal, osmotic or tactile) due to enamel wear or gingival recession, subsequent extreme variations in hydrodyanamic flow of dentinal fluid is perceived as pain by the pulpal nerves. The efficacy of three bioglass powders to occlude patent tubules through the formation of apatite was determined. Methods: Two proprietary powders were produced by sol-gel and pyrolysis (P1) or grinding the dried gel (P2). For comparison an established melt-derived bioglass (P3) was also used. Bioglass-saliva slurry was mechanically applied to dentine possessing exposed tubules (1min) prior to storage in artificial saliva (24h at 36.01.0C). Powder characterisation and an assessment of apatite development and subsequent tubule occlusion was conducted using scanning electron microscopy (SEM), energy disperse x-ray spectroscopy (EDXS) and a focused ion beam (FIB) technique. A non-parametric test of two-independent samples and Mann-Whitney U with Bonferroni correction was applied to determine significance between categorized levels of tubule occlusion. Results: P1 possessed a spherical particulate morphology and mean size of 0.650.19m, P2 and P3 irregular particle morphology and mean size of 7.345.97m and 3.300.42m, respectively. Distinctive apatite development was identified for the three powders. P1 (nano-bioglass) resulted in the development of continuous apatite-rods which appeared tightly adherent to tubule walls from nanoparticles seeded within the tubules. Apatite-rods were identified to a depth of 270m. P2 and P3 produced a tightly adherent continuous apatite layer which occluded previously open tubules. Significant differences in the extent of tubule occlusion were identified, P2 produced significantly less apatite and tubule occlusion compared with P1 and P3 (P<0.05). Conclusions: P1 and P3 produced high levels of tubule occlusion, the potential for retention of apatite-rods (P1) by mechanical and chemical adhesion suggestions the greatest potential for the elimination of dentine hypersensitivity.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Tooth surface loss (TSL) is a common condition and can have a multifactorial aetiology. Toothbrushing and coarse foods are abrasive and can contribute to TSL, particularly when in combination with erosive substances such as dietary acids. The aim of this study was to investigate the effects of a series of common daily meals and toothbrushing referred to as a typical Friday' on TSL. Methods: 25 flat bovine enamel sections were prepared. Samples were divided into 5 groups including control group. A typical Friday diet' was split into three stages representing breakfast (grapefruit juice followed by toast and marmalade), lunch (vegetable pasta and Coca-Cola Zero) and dinner (curry and lager followed by cider and peanuts); brushing followed breakfast and dinner. One group was exposed to all 3 stages whereas the remaining 3 groups were assigned separately to breakfast, lunch or dinner. Specimens were immersed in foodstuffs and stirred at an equivalent linear velocity of 0.25 m.s-1, whilst dry foodstuffs were rubbed onto the specimens. Specimens were brushed in slurry of Colgate Total. Non-contact profilometry was used to quantify TSL. Results: Exposure to a lunchtime meal' caused the least TSL (0.63 m) despite Coca-Cola having the lowest pH of all foodstuffs. Breakfast and dinner involved exposure to abrasive foods immediately following acidic beverages, which resulted in greater TSL (2.99 and 2.71 m respectively). Toothbrushing caused further TSL, particularly after the dinner and drinks stage (1.73 m). Specimens exposed to the full sequence of meals exhibited more TSL than the sum of the individual TSL for the single meals (11.26 and 9.03 m respectively). Conclusion: The cumulative effect of a series of meals has an even greater potential for TSL than single meals and should therefore be considered when identifying erosive potential of single foodstuffs.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Buffer capacity is widely regarded as an important factor in erosive potential of drinks. Differential buffer capacity (β) in the range 1-20 mmol/L/pH influences initial softening of enamel in acids (Barbour and Shellis: Phys Med Biol 2007;52:899-910). The aim was to determine the effect of differential buffer capacity on the rate of dissolution of enamel in citric acid, pH 3.2. Methods: Three slices of enamel were cut from cusps of human molars, the cut surfaces were polished and the natural surfaces varnished. The surface areas of the exposed polished surfaces were measured by planimetry. The rate of enamel dissolution at 36C was determined in a pH-stat. Each specimen was exposed in random order to a series of citric acid solutions, pH 3.2, with concentrations adjusted to give β values of 2.01,5.00, 9.98, 19.87 and 39.95 mmol/L/pH. Results: In the solution with β = 2.01, pH was unstable because of inadequate buffering and dissolution rate was too low to be measured. In the range β = 5.00-39.95, mean dissolution rate increased from 1.40 to 1.99 nmol hydroxyapatite/min/mm2. The least-squares slope of the regression of rate on β was 0.0124 (r2 = 0.46). Conclusions: At this pH, differential buffer capacity has little influence on the rate of enamel dissolution in citric acid. Further work is in progress to determine the effect in other organic acids and at other pH values.
    IADR General Session 2010; 07/2010
  • A. CHAPMAN, S.B. JONES, N.X. WEST
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    ABSTRACT: Objective: Tooth mousse and GC-MI paste plus (GC UK Ltd, Buckinghamshire, UK) both contain Casein Phosphopeptide- Amorphous Calcium Phosphate (CPP-ACP). GC-MI paste plus also contains 900ppm fluoride. Practitioners recommend rubbing these dentifrices directly onto the tooth surface to aid remineralisation or swishing the slurry around the mouth to benefit orthodontic patients with demineralised areas around brackets. The aim of this study was to see how effective different ways of applying both GC dentifrices to pellicle coated enamel is at reducing tooth tissue loss in vitro. Method: Flat specimens (n=6) were prepared from human enamel collected following HTA guidelines. Specimens were immersed in 0.3% citric acid for 10min prior to developing an acquired pellicle by immersion in stimulated whole human saliva for 2h. Four treatment solutions were investigated (tooth mousse with artificial saliva, GC-MI paste plus with artificial saliva, 225ppm fluoride in artificial saliva and artificial saliva). Within each group, treatment solution was applied either by soaking, rubbing or brushing onto the specimen surface for 3min. Specimens were soaked in citric acid for a further 10min. The amount of tissue loss was measured using non-contact profilometry. Results: Applying treatment solution by soaking showed a significant (p<0.05) reduction in surface tissue loss when treated with 225ppm F and GC MI paste plus, whereas rubbing showed a significant reduction in the amount of surface tissue loss when treated with 225ppm F only. There was no significant difference in the amount of tissue loss from either of the treatment solutions when applied by brushing. Combination of soaking in 225ppm fluoride provided the greatest protection against tooth tissue loss. Conclusion: Fluoride provided the greatest reduction in tooth tissue loss overall, followed by GC-MI paste plus. The presence of fluoride within the dentifrice may be more influential than CPP-ACP, especially when applied by soaking.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Sections of flat, polished human enamel are widely used for in situ and in vitro erosion studies. The aim of this study was to investigate any variations in the amount of erosion of enamel samples that had been selected from identified surfaces of teeth taken from pooled wisdom teeth and challenged by citric acid. The objectives were to establish whether variance in erosion was noted when enamel was gathered from different arches (maxillary or mandibular) or different surfaces (mesial, distal, buccal, lingual/palatal) whilst subjected to standardized erosion in vitro. Methods: Fifty teeth (34 maxillary and 16 mandibular teeth) were sectioned using a microtome to produce mesial, distal, buccal, lingual/palatal samples). A cut 200m below the outer surface exposed a flattened window of enamel. Each sample was embedded in a resin block and the exposed sample was polished with sequentially finer powders, culminating in 50m alumina powder. Samples were taped to expose a 1mm window and immersed in 0.3 % citric acid adjusted to pH 3.20 for 30 min at 37C and moving at an equivalent linear velocity of 0.25m.s-1. Samples were measured post erosion using Proscan 2000 non-contact profilometer. Results: Mean (standard deviation) erosion depth was 12.6m(2.3). Multilevel modelling using regression coefficients and 95% confidence intervals were as follows: for location (maxillary/mandibular) adjusted for surface 0.81(-0.05, 1.67)p=0.07. For surfaces adjusted for location: Distal buccal 0.30(-0.52, 1.12)p=0.5; Lingual/Palatal buccal 0.74(-0.07, 1.56)p=0.07; Mesial buccal -0.05(-0.87, 0.76)p=0.9; Lingual/Palatal-distal 0.44 (-0.37, 1.26)p=0.3; Mesial distal -0.35 (-1.17, 0.47)p=0.4; Mesial Lingual/Palatal -0.80 (-1.61, 0.02)p=0.06. Conclusion: The location from which arch or surface of the tooth a sample was taken from did not significantly influence the rate of erosion using wisdom teeth prepared with a minimum depth of 200 m from the natural surface.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Dentine hypersensitivity occurs when patent dentinal tubules are subjected to external thermal, tactile, osmotic or chemical stimuli causing a change in fluid flow within tubules and pulpal nerve depolarisation, interpreted centrally as pain. Products designed to occlude the dentinal tubules have had variable success in reducing dentine hypersensitivity by blocking or reducing the hydrodynamic flow of dentinal tubule fluid. The aim of this study was to assess the efficacy of strontium and arginine pastes at tubule occlusion under acidic challenge, compared with a conventional fluoride paste. Methods: Dentine specimens (total n=200), with patent tubules, were divided into four treatment groups and half-taped to maintain a control section. Four commercially available toothpastes were investigated; a strontium acetate/sodium fluoride paste, a strontium-chloride paste, an arginine-based paste and a sodium monoflorophosphate paste. The toothpastes were mixed with human saliva and rubbed onto the dentine surfaces for 1 minute and a percentage assessed for tubule occlusion. Remaining samples were further subdivided (n=10) and soaked in 0.3% citric acid solution (pH3.2) for 10s, 30s, 2min, 5min and 10min (361.0C), respectively. Specimens were subsequently freeze-dried (-401.0C) and representative images captured with a scanning electron microscope (SEM). Extent of tubule occlusion was assessed by three independent blind reviewers and a non-parametric test of two-independent samples and Mann-Whitney U at 0.95 significance level with Bonferroni correction applied to determine significance between the categorized levels of tubule occlusion. Results: The greatest observed degree of tubule occlusion following exposure to citric acid for 10min was exhibited by the strontium acetate/sodium fluoride paste, followed by arginine-based product, strontium-chloride paste and then fluoride paste. A significant difference was exhibited between strontium acetate/sodium fluoride-based paste and all other pastes at 10min (P≤0.0025). Conclusion: The strontium acetate/sodium fluoride paste exhibited the greatest tubule occlusion of patent dentinal tubules at 10min.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Chewing gum is looked upon as part of our oral health regime, mainly because chewing aids salivary flow and gum serves as an effective delivery mode to the oral cavity. There is currently great interest in a milk derivative protein, casein. Casein phosphopeptide(CPP) is able to bind amorphous calcium phosphate(ACP) which stabilises the structure, prevents precipitation and upon dissociation allows free calcium and phosphate to interact with enamel. The aim was to identify a protective surface deposit on eroded enamel treated with effluent of gums containing CPP-ACP, acid-coated Hubba Bubba gum or a negative control gum. Methods: Enamel specimens were prepared from human molars following HTA guidelines. Specimens were immersed in orange juice until greater than 15m tissue loss was recorded. Effluents of chewing gum were prepared using pestle and mortar to pound chopped pieces of gum containing 0,10,18.8mg of CPP-ACP or Hubba Bubba for 10min in artificial saliva followed by agitation for 60min. Specimens were exposed to the effluent for cumulative time periods of 30,60,90 and 120min. Any deposited layer or further tissue loss following exposure to effluents was measured by profilometry. SEM was also used to identify whether a surface layer had been deposited. Results: Specimens exposed to gums containing CPP-ACP showed no further tissue loss over all time periods except for 10mg CPP-ACP gum after 120min. Specimens exposed to Hubba Bubba showed significantly (p<0.001) more tissue loss than all other gums at each time point. SEM images showed varying degrees of a deposited layer on all specimens whilst those treated with Hubba Bubba showed a more defined eroded structure. Conclusion: CPP-ACP available in gum effluents did not provide additional protection compared to the negative control gum but did not cause further tissue loss, as was evident following treatment with effluent of Hubba Bubba. Funded by CadburyS&T,USA.
    IADR General Session 2010; 07/2010
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    ABSTRACT: Objectives: Biofilm formation on dental implant surfaces can lead to complications and, ultimately, bone loss and implant failure. Functionalisation of TiO2 with chlorhexidine (CHX) has been shown to reduce colonisation by oral bacteria. The adsorption of CHX to TiO2 is pH-dependent and is maximised at pH 5-6. Hence, buffers are often used in experimental CHX solutions to stabilise pH. However, it has been observed that buffers affect CHX adsorption behaviour. The aim of this study was to investigate the impact of MES buffer concentration on the adsorption of CHX to anatase and rutile TiO2 surfaces, and on the pH stability of CHX-MES solutions. Materials and methods: Solutions containing 0 or 50 mg/L CHX and 0, 2, 10 or 50 mM MES were adjusted to pH 6. 10 mg anatase or 50 mg rutile TiO2 was incubated in 1.5 mL CHX-MES solutions for 17 h at 22C under gentle agitation. The supernatant was then separated from the adsorbate by centrifugation at 10000 rpm for 5 min and analysed for CHX concentration by measuring UV absorption at 255 nm. The pH stability of the CHX-MES solutions was also recorded. Results: Polymorph MES concentration [mM] CHX adsorption [mg CHX/ m2 TiO2] (SD) Anatase 0 0.572 (0.017) Anatase 2 0.578 (0.008) Anatase 10 0.489 (0.019) Anatase 50 0.226 (0.013) Rutile 0 0.181 (0.003) Rutile 2 0.180 (0.006) Rutile 10 0.187 (0.008) Rutile 50 0.124 (0.014) Table 1. CHX adsorption to TiO2 as a function of MES buffer concentration The solutions with no buffer showed considerable pH variation (>0.3 units); solutions containing buffer exhibited much less pH variation (>0.15 units). Conclusions: Buffer concentration reduced CHX adsorption to anatase TiO2 at 10 mM and 50 mM, and to rutile TiO2 at 50 mM. Anatase was affected more than rutile presumably because baseline adsorption of CHX is higher. The reduction in CHX adsorption can be explained by competitive adsorption by buffer molecules. pH stability was considered acceptable even at MES concentrations as low as 2 mM.
    IADR General Session 2010; 07/2010
  • A R Curtis, N X West, B Su
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    ABSTRACT: The occlusion of patent dentine tubules may reduce or eliminate hypersensitivity by restricting dentinal fluid movement. The efficacy of a novel sol-gel nanobioglass and a melt-derived bioglass to occlude tubules and promote apatite formation was tested by mechanically brushing a slurry of bioglass powder and human saliva onto dentine possessing exposed tubules. Scanning electron microscopy, focused ion beam and energy-dispersive X-ray spectroscopy were used to characterize the powders and assess tubule occlusion. Melt-derived bioglass possessed an irregular particle morphology and had a mean size of 3.30 +/- 0.42 microm. The sol-gel bioglass particles were spherical, with a mean size of 0.65 +/- 0.19 microm. Dentine treated with melt-derived bioglass exhibited a tightly adherent continuous apatite layer. Treatment with nanobioglass resulted in particle deposition within tubules and formation of apatite rods which were tightly adherent to tubule walls and continuous to a measured depth of 270 microm.
    Acta biomaterialia 03/2010; 6(9):3740-6. DOI:10.1016/j.actbio.2010.02.045 · 5.68 Impact Factor

Publication Stats

1k Citations
91.12 Total Impact Points

Institutions

  • 2014
    • Worldwide Clinical Trials
      Nottigham, England, United Kingdom
  • 2000–2013
    • University of Bristol
      • School of Oral and Dental Sciences
      Bristol, ENG, United Kingdom
    • University of Veterinary Medicine Hannover
      Hanover, Lower Saxony, Germany
  • 2007
    • Bristol Hospital
      Bristol, Connecticut, United States
  • 2004
    • Naval Postgraduate Dental School
      Maryland, United States
  • 1997–2004
    • British Society for Restorative Dentistry
      Bristol, England, United Kingdom