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Objectives:\ud Antibiotic resistance is increasingly a growing global threat. This study aimed to investigate the potential use of newly developed scandium-doped phosphate-based glasses (Sc-PBGs) as an antibacterial and anticariogenic agent through controlled release of Sc3+ ions.\ud \ud Methods:\ud Sc-PBGs with various calcium and sodium oxide contents were produced and characterised using thermal and spectroscopic analysis. Degradation behaviour, ion release, antibacterial action against Streptococcus mutans, anti-matrix metalloproteinase-2 (MMP-2) activity, remineralisation potential and in vivo biocompatibility were also investigated.\ud \ud \ud Results:\ud The developed glass system showed linear Sc3+ ions release over time. The released Sc3+ shows statistically significant inhibition of S. mutans biofilm (1.2 log10 CFU reduction at 6 h) and matrix metalloproteinase-2 (MMP-2) activity, compared with Sc-free glass and positive control. When Sc-PBGs were mounted alongside enamel sections, subjected to acidic challenges, alternating hyper- and hypomineralisation layers consistent with periods of re- and demineralisation were observed demonstrating their potential remineralising action. Furthermore, Sc-PBGs produced a non-toxic response when implanted subcutaneously for 2 weeks in Sprague Dawley rats.\ud \ud Significance:\ud Since Sc3+ ions might act on various enzymes essential to the biological mechanisms underlying caries, Sc-PBGs could be a promising therapeutic agent against cariogenic bacteria.

Background: Thickened fluids are a recognised intervention strategy in use for people with dysphagia. However, their bacterial profile has not previously been examined. Aims: To identify bacteria and changes in bacterial profiles in a range of water sources and thickener preparations over a 5-day period. Methods: Nine experiments were performed using a range of preparations of water (sterile, drinking, non-drinking tap water) and a thickening agent (sterile sachet and a used tin). Findings: No bacteria were grown on serial subcultures of sterile water, both with and without thickener. Drinking, tap and thickened water left at room temperature for 24 hours may become contaminated with environmental organisms. Conclusions: The growth of bacteria in preparations of thickening agent appears to be dependent upon water quality, while the proliferation of bacteria is dependent upon the length of time the preparation is allowed to stand at room temperature.

BackgroundA new NHS dental practice contract is being tested using a traffic light (TL) system that categorises patients as being at red (high), amber (medium) or green (low) risk of poor oral health. This is intended to increase the emphasis on preventative dentistry, including giving advice on ways patients can improve their oral health. Quantitative Light-Induced Fluorescence (QLF™) cameras (Inspektor Research Systems BV, Amsterdam, the Netherlands) also potentially offer a vivid portrayal of information on patients’ oral health.MethodsSystematic review– objective: to investigate how patients value and respond to different forms of information on health risks. Methods: electronic searches of nine databases, hand-searching of eight specialist journals and backwards and forwards citation-chasing followed by duplicate title, abstract- and paper-screening and data-extraction. Inclusion criteria limited studies to personalised information on risk given to patients as part of their health care.Randomised controlled trial (RCT)– setting: NHS dental practice. Objective: to investigate patients’ preferences for and response to different forms of information about risk given at check-ups. Design: a pragmatic, multicentred, three-arm, parallel-group, patient RCT. Participants: adults with a high/medium risk of poor oral health attending NHS dental practices. Interventions: (1) information given verbally supported by a card showing the patient’s TL risk category; (2) information given verbally supported by a QLF photograph of the patient’s mouth. The control was verbal information only (usual care). Main outcome measures: primary outcome – median valuation for the three forms of information measured by willingness to pay (WTP). Secondary outcomes included toothbrushing frequency and duration, dietary sugar intake, smoking status, self-rated oral health, a basic periodontal examination, Plaque Percentage Index and the number of tooth surfaces affected by caries (as measured by QLF).Qualitative study– an ethnography involving observations of 368 dental appointments and interviews with patients and dental teams.ResultsSystematic review – the review identified 12 papers (nine of which were RCTs). Eight studies involved the use of computerised risk assessments in primary care. Intervention effects were generally modest, even with respect to modifying risk perceptions rather than altering behaviour or clinical outcomes. RCT – the trial found that 51% of patients identified verbal information as their most preferred form, 35% identified QLF as most preferred and 14% identified TL information as most preferred. The median WTP for TL was about half that for verbal information alone. Although at 6 and 12 months patients reported taking less sugar in drinks, and at 12 months patients reported longer toothbrushing, there was no difference by information group. Qualitative study – there was very little explicit risk talk. Lifestyle discussions were often cursory to avoid causing shame or embarrassment to patients.LimitationsOnly 45% of patients were retained in the trial at 6 months and 31% were retained at 12 months. The trial was conducted in four dental practices, and five dental practices were involved in the qualitative work.ConclusionsPatients prefer personal, detailed verbal advice on oral health at their check-up. A new NHS dental practice contract using TL categorisation might make this less likely.Future workResearch on how to deliver, within time constraints, effective advice to patients on preventing poor oral health. More research on ‘risk work’ in wider clinical settings is also needed.Trial registrationCurrent Controlled Trials ISRCTN71242343.FundingThis project was funded by the National Institute for Health Research (NIHR) Health Services and Delivery Research programme and will be published in full inHealth Services and Delivery Research; Vol. 8, No. 3. See the NIHR Journals Library website for further project information.

Background : The gold standard for quantifying mineral loss of enamel is transverse microradiography (TMR) and is complimented by the non-destructive quantitative light induced fluorescence (QLF) which measures changes in autofluorescence. Fluorescence loss has been shown to correlate with mineral loss. Building upon the established method, the use of hyperspectral fluorescence imaging (HI) allows the capture of a broader range of wavelengths to quantify fluorescence changes more accurately. Method : Bovine Enamel was demineralised within the dual constant depth film fermenter over 14 days and analysed using TMR, QLF and HI. The mineral change values were compared using Pearson's Correlation Coefficient. Results : The analysis showed a statistically significant correlation that was equal between TMR and HI (r=0.844) and TMR and QLF (r=0.844), but weaker between QLF and HI (r=0.811). Conclusions : The correlations indicate that HI is a promising valid non-destructive method for quantifying mineral loss from bovine enamel that is as accurate as QLF and complements TMR.

Energy-dense food advertising affects children’s eating behaviour. However, the impact of high-sugar food advertising specifically on the intake of sweet foods is underexplored. This study sought to determine whether children would increase their intake of sugar and total energy following high-sugar food advertising (relative to toy advertising) and whether dental health, weight status and socio-economic status (SES) would moderate any effect. In a crossover, randomised controlled trial, 101 UK children (forty male) aged 8–10 years were exposed to high-sugar food/beverage and toy advertisements embedded within a cartoon. Their subsequent intake of snack foods and beverages varying in sugar content was measured. A dental examination was performed, and height and weight measurements were taken. Home postcode provided by parents was used to assign participants to SES quintiles. Children consumed a significantly greater amount of energy (203·3 (95 % CI 56·5, 350·2) kJ (48·6 (95 % CI 13·5, 83·7) kcal); P = 0·007) and sugar (6·0 (95 % CI 1·3, 10·7) g; P = 0·012) following food advertisements compared with after toy advertisements. This was driven by increased intake of the items with most sugar (chocolate and jelly sweets). Children of healthy weight and with dental caries had the greatest intake response to food advertising exposure, but there were no differences by SES. Acute experimental food advertising exposure increases food intake in children. Specifically, high-sugar food and beverage advertising promotes the consumption of high-sugar food items. The debate around the negative health effects of food advertising on children should be widened to include dental health as well as overall dietary health and obesity.

Evidence on the link between starch intake and caries incidence is conflicting, therefore the cariogenicity of starch compared with sucrose was explored using a dual Constant Depth Film Fermenter (dCDFF) biotic model system. Bovine enamel discs were used as a substrate and the dCDFF was inoculated using human saliva. CDFF units were supplemented with artificial saliva growth media at a constant rate to mimic resting salivary flow rate over 14 days. The CDFF units were exposed to different conditions, 2% sucrose or 2% starch 8 times daily and either no additional fluoride or 1450 ppm F- twice daily. Bovine enamel discs were removed at intervals (days 3, 7, 10 and 14) for bacterial enumeration and enamel analysis using Quantitative Light Induced Fluorescence (QLF) and Transverse Microradiography (TMR). Results showed that in the absence of fluoride there was generally no difference in mineral loss between enamel exposed to either sucrose or starch when analysed using TMR and QLF (P > 0.05). In the presence of fluoride by day 14 there was significantly more mineral loss under starch than sucrose when analysed with TMR (P < 0.05). It was confirmed that starch and sucrose are similarly cariogenic within the dCDFF in the absence of fluoride. With the aid of salivary amylase, the bacteria utilise starch to produce an acidic environment similar to that of bacteria exposed to sucrose only. In the presence of fluoride, starch was more cariogenic which may be due to the bacteria producing a more hydrophobic intercellular matrix lowering the penetration of fluoride through the biofilm. This is significant as it indicates that the focus on sugars being the primary cause of caries may need re-evaluating and an increase in focus on carbohydrates is needed as they may be similarly cariogenic as sugars if not more so.

This study reports a novel melt quenched zinc oxide-doped phosphate-based glasses (Zn-PBGs) of varying CaO mol% designated as C11, C12, C13. The glass degradation rate, ions release, antibacterial activity against S. mutans and remineralization potential were investigated. Zn-PBGs showed one order of magnitude higher degradation rate than Zn-free PBG. The highest rate was observed for C11; Na+, Ca2+, Zn2+ and P5+ release followed the same trend. The higher the Zn2+ release, the greater the S. mutans growth inhibition. C11 showed significantly lower mineral loss from enamel than positive and negative controls. Zn-PBGs could be used to reverse enamel demineralization.

Introduction: A new dental contract being tested in England places patients into traffic light categories according to risk (Red = High risk). This reflects health policy which emphasises patients' shared responsibility for their health, and a growing expectation that clinicians discuss health risk in consultations. Alongside this, there are technological developments such as scans and photographs which have generated new, vivid imagery which may be used to communicate risk information to patients. However, there is little evidence as to whether the form in which risk information is given is important. Methods: The PREFER study is a pragmatic, multi-centre, three-arm, patient-level randomised controlled trial, based in four NHS dental practices, from which 400 high/medium risk patients will be recruited. The study compares three ways of communicating risk information at dental check-ups: 1) verbal only (usual care); 2) a Traffic Light graphic with verbal explanation; 3) a Quantitative Light-Induced Fluorescence (QLF) photograph showing, for example, patches of red fluorescence where dental plaque has been present for two days or more (with a verbal explanation). The study assesses patient preferences using the economic preference-based valuation methodology Willingness-to-Pay (WTP). Any changes in oral self-care (for example in tooth-brushing), will be measured by self-report, and clinical outcome data collected by clinicians and extracted from QLF photographs. Predictors and moderators of any behaviour change will be explored using demographic characteristics and psychological variables from the Extended Parallel Process Model. A cost-benefit framework will explore the financial implications for NHS dentistry of the three risk presentation methods. Keywords: Oral health, Health education, Risk, Clinical communication, Behaviour change

Objectives This study investigated previous hypotheses that the tongue can abrade acid softened/eroded enamel surfaces. Methods Twelve upper removable appliances each retaining 2 anterior and 2 posterior human enamel specimens were constructed. Each specimen was exposed to acid on both surfaces, but only one surface was allowed contact with the tongue. Therefore, 96 surfaces were assessed. Appliances were worn from 9.30 to 17.00 Monday to Friday for 22 days. Acid eroded lesions were created by immersing the specimens for 5 min in 50 ml orange juice three times daily. Enamel loss was measured using Quantitative light- induced fluorescence (QLF) and Non- contact profilometry (NCLP) and the differences (D) between tongue (D t ) and palate facing (D P ) surfaces determined. Results %ΔF D(t-p) from the two anterior specimens were greater than from those placed posteriorly with mean values of 15.9% (±9.1) and 14.4% (±8.4), 5.6% (±8.7) and 4.5% (±6.6) respectively. Similarly, NCLP data showed anterior specimens had greater differences for mean step height (MSH) between tongue - facing and the palate - facing (control) surfaces than posterior specimens. MSH D(t-p) values were 59.4 μm (±30.3) for anterior tongue facing surfaces and 55.5 μm (±29.4) for posterior palate facing surfaces. For the posterior specimens MSH was 48.1 μm (±26.1) and 51.7 μm (±30.4) respectively (p Conclusion The greater enamel surface loss of the anterior specimens demonstrates that abrasion by the tongue on acid softened/eroded enamel in situ is likely.

The purpose of this study was to determine whether or not the dual constant-depth film fermenter (dCDFF) is able to produce caries-like enamel lesions and to ascertain further information regarding the performance of this fully functional biological caries model. Conditions were defined by the continuation (CF) or cessation (FF) of a saliva-type growth medium supply during 50-mM sucrose exposures (8 times daily). Hydroxyapatite (n = 3) and bovine enamel (n = 3) substrata were included within each condition and samples extracted after 2, 4, 8, and 16 days. Community profiles were generated for fastidious anaerobes, Lactobacillus spp., Streptococcus spp., mutans streptococci (MS), and Veillonella spp. using selective culture techniques and enamel demineralisation assessed by transverse microradiography. Results demonstrated that the dCDFF model is able to produce caries-like enamel lesions with a high degree of sensitivity where reduced ionic strength within the FF condition increased surface layer mineral deposition. Between conditions, biofilm communities did not differ significantly, although MS in the biofilms extracted from the FF condition rose to a higher proportion (by 1.5 log10 units), and Veillonella spp. were initially greater within the CF condition (by 2.5 log10 units), indicating an enhanced ability for the clearance of low-pKa acids following exposures to sucrose. However, both conditions retained the ability for caries-like lesion formation.

The rapid detection and identification of microorganisms is one of the most important factors in many cases of ill health. The purpose of this study was to determine the fluorescence characteristics of seven oral bacteria using emission spectra with the aim of distinguishing between the bacteria, and to compare fluorescence imaging methods for the direct assessment of oral bacteria. Fluorescence images of each bacterium were obtained under a 405-nm light source using a two-filter system. The emissions of all samples were measured with a fluorescence spectrometer. The complete fluorescence data set collected for each sample employed a three-dimensional data cube. The differences in the autofluorescence characteristics of the seven oral bacteria were determined by principal components analysis (PCA). The fluorescence images of the oral bacteria varied with the genus and the filter system. The three-dimensional excitation-emission matrix fluorescence spectra exhibited distinctive fluorescence features associated with intracellular fluorophores. The seven bacteria could be clearly differentiated on the PCA score plot. The findings of this study indicate that oral bacteria can be identified based on their autofluorescence characteristics. Fluorescence spectroscopy coupled with PCA can be used to detect and classify oral bacteria.

The aim of this work was to evaluate Quantitative Light-induced Fluorescence (QLFTM) as an alternative to the established Logan and Boyce method for determining plaque coverage of dogs’ teeth. In a series of studies in conscious and anesthetized dogs, QLF showed good intra-photographer repeatability (coefficient of variation [CV] of 7.5% for undisclosed teeth) and inter-photographer reproducibility (CV of 3.2% for undisclosed teeth and 8.5% for disclosed teeth). The QLF software accurately identifies areas of plaque as demonstrated by comparison to the variability of 5 human scorers, manually marking plaque on QLF-acquired images ( P = 0.1). There was good agreement with the modified Logan and Boyce method in the percentage reduction in plaque accumulation measured when dogs were fed an oral care chew versus no chew. To see a 15% difference in plaque accumulation, which is considered sufficient by the Veterinary Oral Health Council to differentiate between 2 treatments, a retrospective power analysis (90%) of the data established that only 7 dogs would be required, compared to 19 dogs for the modified Logan and Boyce method. QLF is a reliable method for measuring dental plaque in dogs with the added advantage that it is not subjective and requires fewer animals.

Background Oxygen is generally considered essential for lethal photosensitisation by photodynamic processes. The oral anaerobes, Prevotella intermedia and P. nigrescens are known to be photosensitive, but are also extremely sensitive to the cytotoxic effects of oxygen. Methods The Prevotellaceae were exposed to two 405 nm light sources for different exposure times in an anaerobic chamber. Viable counts of the light exposed samples were compared to light-free controls to determine the proportion of bacteria killed. Results Lethal photosensitivity was demonstrated against P. intermedia and P. nigrescens. The proportions of bacteria killed by either the light-emitting diode or laser pointer were similar at a given energy density (J/cm2). Conclusions Lethal photosensitivity was demonstrated in two species of Prevotella under anaerobic conditions.

The plaque inhibiting properties of magnolia bark extract (MBE) were assessed in a volunteer trial following the consumption of various sugar-free chewing gum formulations over a period of 4-days. Paired t-tests demonstrated significant (p

To investigate the remineralisation of enamel subsurface lesions treated with fluoride toothpaste (1450 ppm) or a combination of fluoride toothpaste in addition to Tooth Mousse™.An in situ, cross-over, randomised controlled trial.Orthodontic department at Liverpool University Dental Hospital, UK.Twelve patients receiving fixed orthodontic treatment.Demineralised subsurface enamel lesions were placed in a carrier and attached onto a fixed orthodontic appliance. Interventions were either standard fluoride toothpaste or CPP-ACP paste (Tooth Mousse™) in addition to the fluoride toothpaste. Participants received both interventions in a randomised order. Transverse microradiography analysis was used to compare lesion mineral content profiles.Mineral loss was reduced by 15.4 and 24.6% between the fluoride and CPP-ACP groups, respectively (p = 0.023). Lesion depth was reduced by 1.6 and 11.1% between the fluoride and CPP-ACP groups, respectively (p = 0.037). Lesion width was reduced by 4.5 and 15.3% between the fluoride and CPP-ACP groups, respectively (p = 0.015).Remineralisation occurred regardless of treatment group allocation. However, the addition of Tooth Mousse™ resulted in a significantly increased remineralisation effect, compared to fluoride alone. Tooth Mousse™ may be beneficial for patients undergoing orthodontic treatment who are at high risk of demineralisation.Registered on Current Control Trials http://www.controlled-trials.com/ISRCTN04899524.

Objective: To describe the bacterial profile of the oral flora during the first two weeks following a stroke, examining changes in the condition of the oral cavity and infections.\ud Background: Dysphagia is common after a stroke and can lead to aspiration pneumonia. Oral flora changes associated with stroke have been implicated as a possible source of bacteria that can cause systemic infections. \ud Materials and methods: Seventy-seven participants were recruited over a period of nine months. Fifty participants had a complete set of swabs taken from four different oral sites and saliva at three time points over a 14 day period. Molecular identification of bacteria was performed on pooled DNA extracted from swabs.\ud Results: A total of 103 bacterial phylotypes were identified, 29 of which were not in the Human Oral Microbiome Database (HOMD). Fourteen of the twenty most common bacterial phylotypes found in the oral cavity were Streptococcal species with Streptococcus salivarius being the most common. The condition of the oral cavity worsened during the study period. Fifteen (30%) patients had at least one infection. \ud Conclusions: It is unknown whether the 29 phylotypes identified that were not in the HOMD indicate a particular change in the oral flora associated with stroke, or the incomplete nature of the HOMD. The Holistic and Reliable Oral Assessment Tool detailed how the condition of the oral cavity following a stroke worsened over the fourteen days in hospital. Further research is needed to explore oral care methods to improve patient safety and comfort following a stroke.

Objective To quantify the prevalence of advertising for foods and beverages potentially detrimental to dental health on UK television watched by children. Design Content analysis of pre-recorded television advertisements (adverts). Materials and methods Three hundred and fifty-two hours of television were recorded (one weekday and one weekend day, 6 am – 10 pm) from the main commercial channel (ITV1). All adverts were coded using pre-defined criteria. Setting UK television recorded between January and December 2012. Results Of 9,151 adverts, foods and beverages were the second most commonly advertised products (16.7%; n = 1,532). Nearly two-thirds of food adverts were for items that are potentially harmful to dental health (61%; n = 934). Of these, 96.6% were cariogenic and 11% were acidogenic foods. During peak children's viewing hours, the proportion of foods that are potentially harmful to dental health was significantly higher than for non-harmful foods (65.9% vs. 34.1%; p = 0.011). Adverts for foods potentially harmful to dental health were rare around children's programmes, but significantly more frequent during other programmes watched by children (p

Item does not contain fulltext BACKGROUND: The non-communicable diseases dental caries and periodontal diseases pose an enormous burden on mankind. The dental biofilm is a major biological determinant common to the development of both diseases, and they share common risk factors and social determinants, important for their prevention and control. The remit of this working group was to review the current state of knowledge on epidemiology, socio-behavioural aspects as well as plaque control with regard to dental caries and periodontal diseases. METHODS: Discussions were informed by three systematic reviews on (i) the global burden of dental caries and periodontitis; (ii) socio-behavioural aspects in the prevention and control of dental caries and periodontal diseases at an individual and population level; and (iii) mechanical and chemical plaque control in the simultaneous management of gingivitis and dental caries. This consensus report is based on the outcomes of these systematic reviews and on expert opinion of the participants. RESULTS: Key findings included the following: (i) prevalence and experience of dental caries has decreased in many regions in all age groups over the last three decades; however, not all societal groups have benefitted equally from this decline; (ii) although some studies have indicated a possible decline in periodontitis prevalence, there is insufficient evidence to conclude that prevalence has changed over recent decades; (iii) because of global population growth and increased tooth retention, the number of people affected by dental caries and periodontitis has grown substantially, increasing the total burden of these diseases globally (by 37% for untreated caries and by 67% for severe periodontitis) as estimated between 1990 and 2013, with high global economic impact; (iv) there is robust evidence for an association of low socio-economic status with a higher risk of having dental caries/caries experience and also with higher prevalence of periodontitis; (v) the most important behavioural factor, affecting both dental caries and periodontal diseases, is routinely performed oral hygiene with fluoride; (vi) population-based interventions address behavioural factors to control dental caries and periodontitis through legislation (antismoking, reduced sugar content in foods and drinks), restrictions (taxes on sugar and tobacco) guidelines and campaigns; however, their efficacy remains to be evaluated; (vii) psychological approaches aimed at changing behaviour may improve the effectiveness of oral health education; (viii) different preventive strategies have proven to be effective during the course of life; (ix) management of both dental caries and gingivitis relies heavily on efficient self-performed oral hygiene, that is toothbrushing with a fluoride-containing toothpaste and interdental cleaning; (x) professional tooth cleaning, oral hygiene instruction and motivation, dietary advice and fluoride application are effective in managing dental caries and gingivitis. CONCLUSION: The prevention and control of dental caries and periodontal diseases and the prevention of ultimate tooth loss is a lifelong commitment employing population- and individual-based interventions. 01 maart 2017

Gallium-doped phosphate-based glasses (Ga-PBG) were assessed for their impact on Streptococcus mutans and dental mineralisation, firstly by disc diffusion assays followed by biofilms grown on nitrocellulose filter membrane (NFM) and constant-depth film fermentor (CDFF). Short-time exposure (10 min) effects of Ga-PBG on S. mutans biofilm were compared with that of 0.2% chlorhexidine. The effects of Ga-PBG on bovine enamel (which was investigated under pH-cycling condition) and dentine were analysed using transverse microradiography (TMR), profilometry and inductively coupled plasma optical-emission spectrometry (ICP-OES). The disc diffusion assays showed inhibition zones of 24.5 ± 0.5 mm for Ga-PBG compared with controls (C-PBG). Ga-PBG showed statistically significant growth inhibition of S. mutans biofilms on NFM (p = 0.001) and CDFF (p < 0.046) compared with hydroxyapatite (HA) and C-PBG. The CDFF assay revealed a maximum of 2.11 log colony-forming unit (CFU) reduction at 48 h, but short-time exposure effects were comparable with that of 0.2% chlorhexidine only on older biofilms (maximum of 0.59 vs. 0.69 log CFU reduction at 120 h). TMR analyses of the enamel revealed non-significant mineral loss (p = 0.37) only in the case of Ga-PBG samples compared with controls including sodium fluoride. ICP-OES analyses indicated transient gallium adsorption into dentine by calcium displacement. The results confirmed that gallium inhibited S. mutans growth and appears to have the potential to protect the enamel surface under conditions representative of the oral environment. Further work is needed to establish whether it has an application in daily oral hygiene procedures to prevent or reduce caries.

Summary Background Lethal photosensitization has been previously demonstrated in Porphyromonas gingivalis, but oxygen is considered to be essential to this process. However, since P. gingivalis is a periodontal pathogen which grows in the low oxygen conditions found in the subgingival crevice, it was considered prudent to study its photosensitivity in anaerobic conditions. Methods A series of experiments were undertaken to attempt to induce lethal photosensitization in P. gingivalis (ATCC 33277) under strict anaerobic conditions using two different 405 nm light sources. Samples of P. gingivalis were grown on a blood-containing, solid growth medium before being suspended in saline and then exposed to 405 nm light delivered by either a hand-held light source (Toothcare™) (11.4 mW/cm2) or a laser pointer (328.5 mW/cm2). With the exception of the adjustment of the P. gingivalis suspensions to a fixed optical density, the experiments were carried out in their entirety within an anaerobic chamber. Results The lowest Toothcare light dose tested (0.34 J/cm2; 30 s) yielded a statically significant kill of 63.4% which increased to 94.1% kill at higher light doses (3.42 J/cm2; 300 s). The laser pointer similarly achieved kills of 90.2% at the lower light dose tested (9.86 J/cm2; 30 s) and 94.5% kill at the highest light dose (98.55 J/cm2; 300 s). Conclusions Lethal photosensitization can be instigated in planktonic suspensions of P. gingivalis at 405 nm delivered by hand-held devices under anaerobic conditions. This suggests the possibility that lethal photosensitization occurred by the oxygen-independent type I pathway as oppose to the oxygen-dependent type II pathway.

Objectives This study reports the development and assessment of a novel method using quantitative light-induced fluorescence (QLF), to determine whether QLF parameters Δ F and Δ Q were appropriate for aiding diagnosis and clinical decision making of early occlusal mineral loss by comparing QLF analysis with actual restorative management. Methods Following ethical approval, 46 subjects attending a dental teaching hospital were enrolled. White light digital (WL) and QLF images/analyses of 46 unrestored posterior teeth with suspected occlusal caries were made after a clinical decision had already been taken to explore fissures operatively. WL and QLF imaging/analysis were repeated after initial cavity preparation. The type of restorative treatment was determined by the supervising clinician independent of any imaging performed. Actual restorative management carried out was recorded as fissure sealant/preventive resin restoration (F/P) or class I occlusal restoration (Rest.) thus reflecting the extent of intervention (=gold standard). All QLF images were analysed independently. Results The results showed statistically significant differences between the two treatment groups Δ F ( p = 0.002) (mean 22.60 – F/P and 28.80 – Rest.) and Δ Q ( p = 0.012) (mean 230.49 – F/P and 348.30 – Rest.). Conclusions Δ F and Δ Q values may be useful in aiding clinical diagnosis and decision making in relation to the management of early mineral loss and restorative intervention of occlusal caries. Clinical significance QLF has the potential to be a valuable tool for caries diagnosis in clinical practice.

Objectives Diet diaries are recommended for dentists to monitor children's sugar consumption. Diaries provide multifaceted dietary information, but patients respond better to simpler advice. We explore how dentists integrate information from diet diaries to deliver useable advice to patients. Methods As part of a questionnaire study of general dental practitioners (GDPs) in Northwest England, we asked dentists to specify the advice they would give a hypothetical patient based upon a diet diary case vignette. A sequential mixed method approach was used for data analysis: an initial inductive content analysis (ICA) to develop coding system to capture the complexity of dietary assessment and delivered advice. Using these codes, a quantitative analysis was conducted to examine correspondences between identified dietary problems and advice given. From these correspondences, we inferred how dentists reduced problems to give simple advice. Results A total of 229 dentists' responses were analysed. ICA on 40 questionnaires identified two distinctive approaches of developing diet advice: a summative (summary of issues into an all-encompassing message) and a selective approach (selection of a main message approach). In the quantitative analysis of all responses, raw frequencies indicated that dentists saw more problems than they advised on and provided highly specific advice on a restricted number of problems (e.g. not eating sugars before bedtime 50.7% or harmful items 42.4%, rather than simply reducing the amount of sugar 9.2%). Binary logistic regression models indicate that dentists provided specific advice that was tailored to the key problems that they identified. Conclusion Dentists provided specific recommendations to address what they felt were key problems, whilst not intervening to address other problems that they may have felt less pressing.

Objectives Current guidance recommends that dental practitioners should routinely give dietary advice to patients, with diet diaries as a tool to help diet assessment. We explored patients' compliance with diet-diaries usage in a paediatric clinic within a teaching hospital setting, where remuneration is not an issue. Objectives were to investigate associated factors affecting diet diaries return rate and the information obtained from returned diaries. Methods A retrospective study of 200 randomly selected clinical records of children aged 5–11 years who had received diet analysis and advice as part of a preventive dental care programme at a dental teaching hospital between 2010 and 2013. Clinical records, with a preventive care pro forma, were included in the study. Data on social and family history, DMFT–dmft, oral hygiene practices, dental attendance and dietary habits were obtained and compared with information given in completed diet-diaries. A deductive content analysis of returned diet-diaries was undertaken using a pre-developed coding scheme. Results Of 174 complete records included in this study, diet diaries were returned in 60 (34.5%) of them. Diet diaries were more likely to be returned by those children who reported that they regularly brushed their teeth (P

A number of anaerobic oral bacteria, notably Prevotellaceae, exhibit red fluorescence when excited by short-wavelength visible light due to their accumulation of porphyrins, particularly protoporphyrin IX. pH affects the fluorescence of abiotic preparations of porphyrins due to transformations in speciation between monomers, higher aggregates, and dimers. To elucidate whether the porphyrin speciation phenomenon could be manifested within a microbiological system, suspensions of Prevotella intermedia and Prevotella nigrescens were examined by fluorescence spectrophotometry while being titrated against NaOH. The initial pH of the samples was6, which was then raised toward the maximum found within a diseased periodontal pocket, being ∼pH 8.7. The intensity of the fluorescence emissions increased between 600 and 650 nm with increasing pH. Peak fluorescence emissions occurred at 635±1 nm with a second emission peak developing with increasing pH at 622 nm. A linear relationship was demonstrated between pH and the log10 ratio of 635:622 nm excitation fluorescence intensities. These findings suggest that the pH range found within the oral cavity could affect the fluorescence of oral bacteria in vivo, which may in turn have connotations for any clinical diagnoses that may be inferred from dental plaque fluorescence.

Objective: To assess the use of Quantitative Light-induced Fluorescence-Digital as an oral hygiene evaluation tool during orthodontic treatment. Materials and Methods: In this prospective, randomized clinical trial, 33 patients undergoing fixed orthodontic appliance treatment were randomly allocated to receive oral hygiene reinforcement at four consecutive appointments using either white light (WL) or Quantitative Light-induced Fluorescence-Digital (QLF) images, taken with a device, as visual aids. Oral hygiene was recorded assessing the QLF images for demineralization, by fluorescence loss (ΔF), and plaque coverage (ΔR30). A debriefing questionnaire ascertained patient perspectives. Results: There were no significant differences in demineralization (P = .56) or plaque accumulation (P = .82) between the WL and QLF groups from T0 to T4. There was no significant reduction in demineralization, ΔF, in the WL, or the QLF group from T0–T4 (P > .05); however, there was a significant reduction in ΔR30 plaque scores (P < .05). All the participants found being shown the images helpful, with 100% of the QLF group reflecting that it would be useful to have oral hygiene reinforcement for the full duration of treatment compared with 81% of the WL group (OR 2.3; P < .05). Conclusions: Quantitative Light-induced Fluorescence-Digital can be used to detect and monitor demineralization and plaque during orthodontics. Oral hygiene reinforcement at consecutive appointments using WL or QLF images as visual aids is effective in reducing plaque coverage. In terms of clinical benefits, QLF and WL images are of similar effectiveness; however, patients preferred the QLF images.

Phosphate-based glasses (PBGs) are excellent controlled delivery agents for antibacterial ions such as silver and gallium. The aim of this study was to assess the potential utility of novel PBGs combining both gallium and silver for use in periodontal therapy. To this end, an in vitro biofilm model with the putative periodontal pathogen, Porphyromonas gingivalis, and an initial colonizer, Streptococcus gordonii, was established. The effect of increasing calcium content in gallium-silver-doped PBG on the susceptibility of P. gingivalis was examined. A decrease in degradation rates (30.34, 25.19, 21.40 μg mm(-2) h(-1)) with increasing PBG calciumcontent (10, 11, 12 mol.% respectively) was observed, correlating well with gallium and silver ion release and antimicrobial activity against planktonic P. gingivalis (approximately 5.4log(10) colony-forming units (CFU) reduction after 24h by the C10 glass compared with controls) and S. gordonii (total growth inhibition after 32h by C10, C11 and C12 glasses compared with controls). The most potent PBG (C10) was evaluated for its ability to inhibit the biofilm growth of P. gingivalis in a newly established constant-depth film fermentor model. The simultaneous release of silver and gallium from the glass reduced P. gingivalis biofilm growth with a maximum effect (1.92log(10) CFU reduction) after 168 h. Given the emergence of antibiotic-resistant bacteria and dearth of new antibiotics in development, the glasses, especially C10, would offer effective alternatives to antibiotics or may complement current therapies through controlled, localized delivery of gallium and silver ions at infected sites in the oral cavity.

Introduction Our aim was to determine predictors for the presence and degree of demineralization during orthodontic treatment. This study was a post-hoc analysis of recruits for a randomized controlled trial. Two hundred thirty patients were included in this study and assessed for demineralization at debond by using quantitative light-induced fluorescence to determine their eligibility for a randomized controlled trial assessing the effectiveness of various toothpastes at reducing demineralization during retention. Methods Data about patients' demographics, treatments, oral hygiene, and pretreatment status of the first permanent molars were extracted from case notes. Data on the presence and severity of white spot lesions (WSLs) were obtained from the trial's data base. Univariate analyses and multiple regression were undertaken to assess for associations between the factors and the presence and severity of WSLs. Results Sixty-five patients (28.3%) had no WSLs, and 165 (71.7%) had 1 to 12. The mean number of WSLs per patient with demineralization was 2.9 (95% CI, 2.5 and 3.3). Patients with WSLs were significantly ( P = 0.002) younger and more likely to have diseased first molars ( P = 0.04). Participants with inadequate pretreatment oral hygiene developed more WSLs ( P = 0.03). Boys ( P = 0.001) and participants with diseased first molars ( P = 0.06) had significantly greater demineralization. Conclusions Sex, pretreatment age, oral hygiene, and clinical status of the first molars can be used as predictors for the development and severity of WSLs during orthodontic treatment.

The aim was to study the effects of zinc (Zn) and fluoride (F) on remineralisation at plaque fluid concentrations. Artificial carious lesions were created in 2 acid-gel demineralising systems (initially infinitely undersaturated and partially saturated with respect to enamel) giving lesions with different mineral distribution characteristics (high and low R values, respectively) but similar integrated mineral loss values. Lesions of both types were assigned to 1 of 4 groups and remineralised for 5 days at 37°C. Zn and F were added, based on plaque fluid concentrations 1 h after application, to give 4 treatments: 231 µmol/l Zn, 10.5 µmol/l F, Zn/F combined and an unmodified control solution (non-F/non-Zn). Subsequently remineralisation was measured using microradiography. High-R lesions were analysed for calcium, phosphorus, F and Zn using electron probe micro-analysis. All lesions underwent statistically significant remineralisation. For low-R lesions, remineralisation was in the order Fa < non-F/non-Zna < Zna, b < Zn/Fb, and for high-R lesions Fa < non-F/non-Znb < Znb < Zn/Fc (treatments with the same superscript letter not significantly different, at p < 0.05). Qualitatively, remineralisation occurred throughout non-F/non-Zn and Zn groups, predominantly at the surface zone (F) and within the lesion body (Zn/F). Electron probe micro-analysis revealed Zn in relatively large amounts in the outer regions (Zn, Zn/F). F was abundant not only at the surface (F), but also in the lesion body (Zn/F). Calcium:phosphate ratios were similar to hydroxyapatite (all). To conclude, under static remineralising conditions simulating plaque fluid, Zn/F treatment gave significantly greater remineralisation than did F treatment, possibly because Zn in the Zn/F group maintained greater surface zone porosity compared with F, facilitating greater lesion body remineralisation.

Background and Objective: Many species of oral bacteria can be induced to fluoresce due to the presence of endogenous porphyrins, a phenomenon that can be utilized to visualize and quantify dental plaque in the laboratory or clinical setting. However, an inevitable consequence of fluorescence is photobleaching, and the effects of this on longitudinal, quantitative analysis of dental plaque have yet to be ascertained. Material and Methods: Filter membrane biofilms were grown from salivary inocula or single species (Prevotella nigrescens and Prevotella intermedia). The mature biofilms were then examined in a custom-made lighting rig comprising 405 nm light-emitting diodes capable of delivering 220 W/m 2 at the sample, an appropriate filter and a digital camera; a set-up analogous to quantitative lightinduced fluorescence digital. Longitudinal sets of images were captured and processed to assess the degradation in red fluorescence over time. Results: Photobleaching was observed in all instances. The highest rates of photobleaching were observed immediately after initiation of illumination, specifically during the first minute. Relative rates of photobleaching during the first minute of exposure were 19.17, 13.72 and 3.43 arbitrary units/min for P. nigrescens biofilms, microcosm biofilm and P. intermedia biofilms, respectively. Conclusion: Photobleaching could be problematic when making quantitative measurements of porphyrin fluorescence in situ. Reducing both light levels and exposure time, in combination with increased camera sensitivity, should be the default approach when undertaking analyses by quantitative light-induced fluorescence digital.

The purpose of this study was to compare detection of enamel and dentinal caries by dental students' and faculty members' visual inspection and by quantitative light-induced fluorescence (QLF). The overall aim was to determine whether QLF is an appropriate technique for use in clinical skills laboratories as a teaching aid for dental undergraduates to detect and assess the removal of enamel and dentinal caries. Sixty students who had no clinical experience with dental caries were asked to select . suitably decayed teeth and mount them in plaster. After recording baseline QLF images, students removed caries according to instructions given by the clinical tutor. On completion of the exercise, the teeth were visually determined to be caries-free by the student, then confirmed by the clinical tutor. A fluorescein in alcohol solution was injected into the cavity for two minutes, rinsed, and dried before QLF images were captured. The images were visually analyzed by two examiners for the presence or absence of caries. From seventy-four images recorded, seventeen were excluded due to exposure of the pulp chamber. The remaining fifty-seven teeth, which by clinical visual examination were judged to be caries-free, were examined using QLF. Fifty-three percent were found to be caries-free, while 47 percent were carious. In this sample of fifty-seven teeth judged to be caries-free by both dental students and faculty members, QLF thus detected caries in almost half of these teeth. These findings suggest that QLF is a useful, noninvasive, nondestructive technique for the detection of caries and can serve as an adjunct to chair-side diagnosis and management of dental caries, which is typically accomplished by visual inspection. QLF may be useful and appropriate as an objective clinical teaching aid for the assessment of dental caries.

Objectives: To report the use of Quantitative Light-induced Fluorescence (QLF) to determine if there was a tendency for bleached enamel to take up extrinsic stains more than unbleached enamel. Methods: Bovine teeth devoid of stains were selected, the roots removed and enamel gently pumiced. Each tooth was sectioned into two and each half randomly assigned to two groups (bleached or unbleached). Windows were created on each half using clear acid resistant varnish. 38% Hydrogen peroxide gel was applied to the exposed windows of the bleached group for 1 hour. The teeth were rinsed and dried. Bleached and unbleached halves of the same teeth were then mounted on glass rods attached to pot lids using green stick. QLF images were taken. The teeth were subjected to a cycle of artificial saliva, chlorhexidine and tea (2 minutes in each solution). This was repeated 5 times. QLF images were taken at the end of each cycle. Results: The uptake and progression of stain was detected in all the sections by QLF. Using paired t- test (SPSS) there was no significant difference between the two groups for the change from baseline to the final stain cycle (p>0.05), however there was variability in stain uptake within the groups as the cycles progressed. Conclusion: Bleaching of enamel in vitro does not appear to increase the susceptibility of enamel to extrinsic staining.

Objectives: The efficacy of three techniques for the disinfection of artificial sub-surface root caries lesions and their response to subsequent episodes of de- and remineralization was investigated quantitatively in vitro. Methods: Sub-surface dentinal lesions (n = 20), cut into four experimental blocks and deliberately contaminated with Streptococcus mutans, were subject to either steam autoclaving (121 8C, 5 min), gamma irradiation (4100 Gy), immersion in 0.1% (w/v) thymol-distilled water solution (24 h) or reserved as a control. Next, the lesions wereincubated aerobically in sterile nutrient broth for 24 h at 37 8C and resultant cultures plated onto blood agar and neutralisation agar. Ten blocks from each experimental group were then immersed in an acidic buffer solution or exposed to artificial saliva for 5 days. Baseline changes in the mineral content and distribution of the lesions were assessed by transverse microradiography (TMR). Results: Micro-organisms were recovered from each control block and one block treated by gamma irradiation. Steam autoclaving and immersion in a thymol solution significantly decreased (p < 0.05) the amount of mineral lost from the body of lesions subject to a further acid challenge. Mineral ion uptake by lesions exposed to artificial saliva was significantly increased (p < 0.05) through disinfection by steam autoclaving. Conclusions: Gamma irradiation proved the most acceptable method for the disinfection of sub-surface root dentine lesions having the least adverse effect on demineralization and remineralization.

This study aimed at evaluating the potential effect of gallium-incorporated phosphate-based glasses towards periodontitis-associated bacteria, Porphyromonas gingivalis, and matrix metalloproteinase-13. Periodontitis describes a group of inflammatory diseases of the gingiva and supporting structures of the periodontium. They are initiated by the accumulation of plaque bacteria, such as the putative periodontal pathogen Porphyromonas gingivalis, but the host immune response such as elevated matrix metalloproteinases are the major contributing factor for destruction of periodontal tissues. Antibacterial assays of gallium-incorporated phosphate-based glasses were conducted on Porphyromonas gingivalis ATCC 33277 using disc diffusion assay on fastidious anaerobe agar and liquid broth assay in a modified tryptic soy broth. In vitro study investigated the effect of gallium on purified recombinant human matrix metalloproteinase-13 activity using matrix metalloproteinase assay kit. In vivo biocompatibility of gallium-incorporated phosphate-based glass was evaluated in rats as subcutaneous implants. Antibacterial assay of gallium displayed activity against Porphyromonas gingivalis (inhibition zone of 22 ± 0.5 mm compared with 0 mm for control glass, c-PBG). Gallium in the glass contributed to growth inhibitory effect on Porphyromonas gingivalis (up to 1.30 reductions in log 10 values of the viable counts compared with control) in a modified tryptic soy broth. In vitro study showed gallium-incorporated phosphate-based glasses inhibited matrix metalloproteinase activity significantly ( p ≤ 0.01) compared with c-PBG. Evaluation of in vivo biocompatibility of gallium-incorporated phosphate-based glasses in rats showed a non-toxic and foreign body response after 2 weeks of implantation. The results indicate that gallium ions might act on multiple targets of biological mechanisms underlying periodontal disease. Moreover, gallium-incorporated phosphate-based glasses are biocompatible in a rat model. The findings warrant further investigation and will have important clinical implications in the future treatment and management of periodontitis.

Summary Objectives To discuss the key elements for establishment of a preventive programme for dental erosion. Data and sources The data discussed are primarily based on published scientific studies and reviews from case reports, clinical trials, epidemiological, cohort, animal, in vitro and in vivo studies. References have been traced manually or by MEDLINE ® . Study selection The aetiology, pathogenesis and modifying factors of dental erosion were reviewed. Strategies to either prevent the occurrence or limit the damage of dental erosion or protect the remaining tooth tissues from further erosive destruction were reviewed and discussed. These includes: (A) measures to (1) enhance remineralisation and acid resistance of enamel surface softened by erosive challenge, (2) reduce the erosive potential of acidic products, (3) enhance salivary flow, (4) protect and restore erosively damaged tooth, and (5) provide mechanical protection against erosive challenge. (B) Health education geared towards (1) diminution of frequency of intake of dietary acids, and (2) change of habits and lifestyles that predispose teeth to erosion development. Conclusions It may be easier to gain patients' compliance with the advice that immediately following an acidic challenge, a remineralising agent, such as fluoride mouthrinses, fluoride tablets, fluoride lozenges or dairy milk, should be administered to enhance rapid remineralisation of the softened tooth surface as well as serve as a mouth refresher, or an alternative, a neutralising solution should be used. Effective counselling on erosion preventive regimes should involve all healthcare personnel, dentists, doctors, pharmacist, nurses/hygienists and clinical psychologists.

The paper describes preliminary in vitro investigations, the objectives of which were to examine the influence of certain experimental parameters on artificial carious lesion formation in root hard tissues, and their remineralisation. These experiments formed part of a wider study that aimed to develop an in situ model of root caries, based on the existing coronal caries model used in Liverpool. The present studies examined the effects (a) of the anatomical origin of the dentine, the presence or absence of cementum, the exposure time and the type of demineralising system, on lesion development, and (b) of baseline lesion size on the extent and location of mineral re-precipitation.Mineral content parameters in plano-parallel sections taken from dentine lesions were determined by computer-controlled transverse microradiography.The importance of the anatomical origin of the dentine on lesion formation was investigated by comparing in vitro lesion formation in premolar and molar dentine, and in dentine from apical, middle and coronal thirds of the root: no difference was observed between these sites. Lesions formed more rapidly in acid buffer solutions than in acid gel systems, and were more reliably produced when cementum was removed. The effect of baseline lesion size on subsequent in vitro remineralisation demonstrated that a small baseline mineral content was associated with a larger percentage mineral gain. The location of mineral deposition throughout the lesion was also influenced by baseline mineral content parameters.The results form a basis for the further development of an in situ dentinal caries model, providing data to suggest that manipulation of parameters involved in the preparation of artificial carious lesions has a significant effect on the behaviour of the lesion, particularly the phenomenon of remineralisation. Further work is needed to investigate the behaviour of the model in situ.

Summary Objectives To review the established and novel methods of plaque quantification employed in dental research, including a discussion of their merits and to present a new method of planimetrically measuring plaque using light induced fluorescence. Method Quantitative light-fluorescence (QLF) images were acquired from the buccal surfaces of an individual who had refrained from oral hygiene both with and without traditional plaque disclosure. Digital photographs were also taken. Images were analysed using a novel method and a percentage plaque index produced. Results Traditional plaque indices are problematic due to their integral nature and their failure to detect small, but potentially clinically relevant changes in plaque area. The use of a fluorescent technique demonstrated good reliability although there was no correlation between red fluorescent plaque and total disclosed plaque suggesting that the auto-fluorescing plaque is not a good measure of total plaque volume. Conclusions The use of planimetric techniques can increase the power of plaque studies, potentially reducing the number of subjects and time required to separate therapies or products. Fluorescent methods of quantification have potential as they enable clear separation of the plaque covered and non-covered tooth surfaces.

Objective To determine the effects of a detergent-free, whitening dentifrice using an in vivo plaque regrowth model with the novel application of QLF as a planimetric analysis tool. Method A total of 20 subjects took part in a double blind, single-centre, crossover study in which slurry rinses were the only form of plaque control over a 5-day period. Following a washout and prophylaxis the subjects used 2 daily rinses in the absence of all other plaque control methods. Subjects returned to the clinic on the afternoon of day 5 when plaque was disclosed and assessed by the plaque index and area using both a photographic and novel fluorescent planimetric technique. A further 9-day washout was carried out and the rinse period repeated to ensure that each subject had used both experimental and comparator slurries. Results Twenty subjects completed the trial. The test product showed a significant inhibition of plaque re-growth (16.9%) compared with a fluoride-matched comparator using the Turesky index (P < 0.0001), the photographic planimetric technique (17.5%) (P < 0.0001) and the novel QLF technique (18.4%) (P < 0.0001). Conclusion The results confirm that plaque inhibition capability of a detergent-free whitening dentifrice is at least as effective as a fluoride matched comparator. QLF is a promising tool for disclosed plaque quantification.

The purpose of this study was to determine the effect of hydration [distilled water (DH2O) and saliva] on lesions of varying severity and determine an optimal drying method to obtain reliable quantitative light-induced fluorescence (QLF) readings. Ten previously extracted molars were placed into a demineralizing solution for 7, 14 and 21 days. Between each demineralizing cycle the teeth were removed. To test for in vitro reliability the teeth were rinsed in DH2O for 1 min and then QLF images were taken every 10 s (control cycle with no drying employed - bench drying only). This was repeated following (i). compressed air drying for 30 s or 15 s and (ii). 30 s cotton wool roll application (CWR). To test for in vivo reliability the experiment was repeated using whole human saliva in place of DH2O. Control groups demonstrated the effect of hydration on QLF reliability; at 7 days reliable results were obtained after 370.4 s (DH2O) and 432.3 s (saliva). Air drying of both DH2O and saliva-rinsed teeth reduced reliability time to 2.1 (+/-6.0) and 3.2 s (+/-7.6), respectively. Cotton wool roll application produced reliable results in 89 s with DH2O and 110 s with saliva. As lesion severity increased [14 days mean deltaQ 115 (+/-90.2), 21 days mean deltaQ 168.0 (+/-120.7)] time to reach reliability significantly increased under control drying and CWR (P > 0.05). Time taken for compressed air-dried teeth to produce reliable results was not significantly different across the groups. Compressed air-drying for 15 s produces reliable results with both DH2O and saliva-hydrated lesions. Future in vivo experiments will be required to determine if the air-drying can be reduced further in a clinical situation.

The use of fluorescein-enhanced quantitative light-induced fluorescence (QLF) in the detection of in vitro root caries demineralization and reminerlization was investigated. Fourteen previously extracted human premolar roots were selected and determined to be caries-free. Cementum was removed and nail varnish applied leaving an exposed window. Positive and negative controls were selected. During a demineralizing regimen, roots were removed at regular intervals (12, 48, 72 and 120 h) and immersed in sodium fluorescein (0.2 mg L(-1)). Following gentle rinsing, each root was examined using QLF before being returned to the demineralizing solution. Following 120 h, each tooth was sectioned through the lesion and one-half retained for transverse micro radiography (TMR) analysis. The remaining half were subjected to a remineralizing regimen undergoing the same fluorescein and QLF examinations at 7, 28 and 36 days. Results showed that QLF effectively monitored demineralization/remineralization of root dentine as represented by fluorescein penetration. TMR analysis showed good correlations with QLF (DeltaZ/DeltaQ) after demineralization (r = 0.89) and remineralization (r = 0.84). The technique could represent an in vivo method for root caries detection and classification.

OBJECTIVES: To test the hypothesis that etching enamel with 37% phosphoric acid for 30 s does not lead to detectable mineral loss when measured with transverse microradiography (TMR). DESIGN: An in vitro laboratory investigation. EXPERIMENTAL VARIABLE: Forty bovine incisors were used in the experiment. The crowns of the teeth were covered with acid resistant varnish except for a rectangular area on the labial surface approximately 10 x 12 mm. On the exposed labial surface of 20 teeth an enamel lesion similar to that used in the in situ caries model was induced. Twenty teeth were left without a lesion. The exposed area was divided into three areas of equal size. The control area (C) was covered with acid resistant varnish throughout the experiment. The first experimental area (E1) was etched with 37% phosphoric acid for 30 s and a simulated bracket was bonded to the surface with composite resin. The second experimental area (E2) was left exposed for the remainder of the experiment. The teeth were placed in a demineralizing solution for 24, 48, 72 or 96 h to replicate different cariogenic challenges. OUTCOME MEASURE: Mineral loss as measured with TMR. RESULTS: There were no significant differences in the mineral loss between etched (E1) and etched (C) areas of enamel. There were significant differences in mineral loss between E1 and E2 for the 48 h (p < 0.001) and 72 h (p = 0.001) exposures without a pre-formed enamel lesion. CONCLUSION: There is no detectable mineral loss with TMR when enamel has been etched for 37% phosphoric acid for 30 s. The use of in situ enamel specimens with acid etch retained simulated brackets to investigate demineralization during orthodontics will not significantly affect the outcome compared with unetched specimens.

The purpose of this study was to determine whether quantitative light-induced fluorescence (QLF) could detect very early demineralization and remineralization longitudinally adjacent to orthodontic components in an in vitro model. Extracted human premolars (n = 13) were sectioned sagittally to produce two equal halves and an orthodontic cleat was bonded to the buccal surface of each tooth. Transparent nail varnish was placed over the remaining surface, leaving exposed enamel windows adjacent to the cleat on the coronal and gingival aspects. Each half-tooth was placed into the lid of an Eppendorf tube and randomly assigned to either control (distilled water) or experimental (lactic acid demineralizing buffer, pH 4.5) regimes. Digital photographs and QLF baseline images were taken. The tubes were mounted into a rotating holder and left for 24 hours. QLF and digital photographs were taken, the solutions refreshed and the teeth returned. This was continued every 48 hours for 288 hours. At this time the lactic acid buffer was replaced with a remineralizing solution (artificial saliva, fluoride, calcium) and the experiment continued with weekly examinations. QLF images were analysed and deltaQ at the 5 per cent threshold recorded. Analysis of the QLF images showed that both demineralization and remineralization were identified and monitored. Statistical differences between each of the timed examinations were found (P < 0.05). Analysis of the photographs demonstrated that QLF detected subclinical lesions. This initial pilot study has demonstrated the potential for QLF to longitudinally monitor de- and re-mineralization of enamel adjacent to orthodontic cleats in vitro.

SUMMARY The aim of this investigation was to compare the repeatability of measuring enamel demineralization surrounding an orthodontic bracket using two techniques: computerized image analysis from digitally converted photographic slides and quantitative light-induced fluorescence (QLF). Fifteen human molars were halved and shaped to look like incisors. The teeth were individually numbered and orthodontic brackets bonded to the buccal surface. The crowns were covered with acid resistant varnish, except for windows approximately 1.5 x 3 mm adjacent to the gingival, occlusal, mesial, and distal edges of the bracket. The windows were variously exposed to a demineralizing gel for 0, 3, 7, or 14 days, and the acid resistant varnish was removed. Standardized photographic slides and QLF images of the teeth were taken. These were repeated after 1 week. The slides were converted to grey scale digital format and analysed using Image-Pro Plus 3.0. The QLF images were stored, processed, and analysed using customized software. All images were recoded for blind analysis. The four surfaces of the bracket were inspected and only areas of suspected demineralization were analysed. This was repeated after 1 week. The limits of agreement and mean difference between repeat readings of the area of demineralization were similar for both techniques (-0.04 ± 0.43 for photographs and -0.10 + 0.63 for QLF). Mean grey level (photographs) and mean loss of fluorescence from that area (AF) (QLF) showed acceptable limits of agreement. The Intra Class Correlation (ICC) was below 0.81 for the measurement of area from QLF, suggesting that random error needs to be reduced. There was evidence of systematic bias for the repeat readings of the grey levels from the photographs (P< 0.001). Enamel demineralization surrounding an orthodontic bracket can be measured reproducibly using these two techniques.

SUMMARY This is Part 2 of an in vitro study investigating two techniques for recording and quantifying demineralization surrounding orthodontic brackets. In Part 1 the repeatability of computerized image analysis from digitally converted photographic slides and quantitative light-induced fluorescence (QLF) was explored. In Part 2 of the investigation the validity of each technique was examined. Thirty halved human molars, shaped to look like incisors and with an orthodontic bracket bonded to the buccal surface were used. A small area of each of the four edges of the bracket was variously exposed to a demineralizing gel for 0, 3, 7, or 14 days. Images of the teeth were taken and analysed using the two techniques. Repeat images and analysis were carried out blind. The sensitivity, specificity, positive, and negative predictive values were calculated. A negative result confirmed that there was no demineralization present in the majority of cases. A positive result was less reliable particularly for the occlusal and gingival regions. The 7- and 14-day demineralization patterns were detected every time using the photographic technique. The discrimination of the 0- and 3-day patterns was less reliable. The results of this study were extrapolated to allow for the prevalence of the condition following orthodontic treatment, and the implications of this for a putative clinical trial are discussed, together with the advantages and disadvantages of each method. Either technique would be applicable to use in a clinical trial.

The influence of abrasion from oral soft tissues on softened enamel lesion remineralization and erosion development was investigated. Using orange juice, softened enamel lesions were produced on 20 human premolars assigned randomly to 10 volunteers. Sections used as control and two test slabs were cut from each tooth. One of the two slabs from each tooth had an appliance built on it, which protected the lesion from abrasion. The two slabs (with/without appliance) were bonded to the palatal surfaces of upper right and left lateral incisor teeth of the participants who chewed sugar-free gum four times daily. After 28-day intra-oral exposure, mineral loss (Delta Z) and lesion depth (ld) in both control and test samples were quantified using transverse microradiography, and the data was analysed by paired t-test. Delta Z was significantly lower in lesions with appliance (protected), but higher in lesions without appliance (unprotected) when compared with control (unexposed). Similar pattern was observed with lesion depth. In unprotected slabs the lesions were abraded resulting in eroded enamel lesions. It was concluded that erosion observed clinically is the combined effect of demineralization of the tooth surface by an erosive agent and abrasion of the demineralized surface by surrounding oral soft tissues and through food mastication. Abrasion from oral soft tissues can contribute to site-specificity of dental erosion.

A range of esthetic restorative dental materials are now available to dental clinicians. The aim of this study was to evaluate the relative fluoride recharge potential of a number of these materials in vitro over two years.Disc samples (12 mm x 2 mm) of each of the materials were placed into artificial saliva at neutral pH. The materials tested were: two glass ionomers (Chemfil; Ketac-Fil), two resin-modified glass ionomers (Photac-Fil Aplicap; Vitremer), two compomers (Dyract; Compoglass) and two composites (Heliomolar; Concise). At 13 intervals over a two years period the discs were subjected to a 2 min fluoride recharge by exposure to sodium fluoride (500 ppm F). The pre- and post-recharge fluoride release values were determined using an ion sensitive electrode.At all time intervals the post-recharge fluoride release of the materials was significantly different (MANOVA p0.0001). The mean values for post-recharge fluoride release after two years were: Chemfil 10.3, Ketac 3.0, Vitremer 9.0, Photac-Fil Aplicap 12.1, Compoglass 5.0, Dyract 3.6, Concise 0.3, Heliomolar 0.2 (units = microgF/cm(2)/h).Esthetic fillings vary significantly in their capacity to absorb and re-release fluoride. The glass ionomer-based materials displayed a far greater potential for fluoride recharge than the composites, in which the recharge was virtually negligible. Whilst it cannot be assumed that fluoride release is directly proportional to cariostatic potential, these results suggest that, where possible, glass ionomer-based materials should be used in patients who have a high caries rate.

The in situ caries model was used to assess the clinical benefit of fluoride-releasing elastomeric ligatures. The design of the experiment was a longitudinal, prospective, randomized, crossover clinical trial. Fourteen individuals starting orthodontic treatment with fixed appliances were recruited. Three in situ enamel specimens, with preformed subsurface carious lesions, were prepared for each patient, from human premolars. Two were placed in customized holders and one was retained as a control specimen. A crossover design was used so that patients had two experimental periods of six weeks with either fluoridated or non-fluoridated elastomerics, and a washout between. Elastomerics were randomly allocated at the first visit and one enamel specimen was placed at the beginning and collected at the end of each experimental period. The specimens were sectioned and ground to 100 microns, and transverse microradiography was carried out. They were analysed using dedicated computer software. The outcome measure was the change in the parameters of the pre-formed carious lesion, expressed as mineral loss (delta Z), lesion depth (ld), lesion width (lw), and ratio (delta Z/ld) between the three specimens. The mean mineral loss (vol %.micron) for the control specimen was 403.7 (+/- 139.5), compared with 599.3 (+/- 515.4) for the non-fluoridated ligatures and 477.2 (+/- 298.4) for the fluoridated ligatures. A one-factor within subjects ANOVA showed no statistical difference between the groups (P = 0.376). Fluoride-releasing ligatures do not provide a significant anti-cariogenic benefit in patients undergoing orthodontic treatment. This may be due to the short-term nature of the fluoride release. However, they might affect the local environment surrounding the bracket.