Novel lactoferrin-conjugated gallium complex to treat Pseudomonas aeruginosa wound infection.

Pseudomonas aeruginosa is one of the leading causes of opportunistic infections such as chronic wound infection that could lead to multiple organ failure and death. Gallium (Ga3+) ions are known to inhibit P. aeruginosa growth and biofilm formation but require carrier for localized controlled delivery. Lactoferrin (LTf), a two-lobed protein, can deliver Ga3+ at sites of infection. This study aimed to develop a Ga-LTf complex for the treatment of wound infection. The characterisation of the Ga-LTf complex was conducted using differential scanning calorimetry (DSC), Infra-Red (FTIR) and Inductive Coupled Plasma Optical Emission Spectrometry (ICP-OES). The antibacterial activity was assessed by agar disc diffusion, liquid broth and biofilm inhibition assays using the colony forming units (CFUs). The healing capacity and biocompatibility were evaluated using a P.aeruginosa infected wound in a rat model. DSC analyses showed thermal transition consistent with apo-lactoferrin; FTIR confirmed the complexation of gallium to lactoferrin. ICP-OES confirmed the controlled local delivery of Ga3+. Ga-LTf showed a 0.57 log10 CFUs reduction at 24 h compared with untreated control in planktonic liquid broth assay. Ga-LTf showed the highest antibiofilm activity with a 2.24 log10 CFUs reduction at 24 h. Furthermore, Ga-LTf complex is biocompatible without any adverse effect on brain, kidney, liver and spleen of rats tested in this study. Ga-LTf can be potentially promising novel therapeutic agent to treat pathogenic bacterial infections.

Antibacterial, remineralising and matrix metalloproteinase inhibiting scandium-doped phosphate glasses for treatment of dental caries.

OBJECTIVES: 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. METHODS: 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. RESULTS: 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. SIGNIFICANCE: 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.

Quantifying the demineralisation of enamel using a hyperspectral camera measuring fluorescence loss.

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. METHODS: 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.

The cariogenic effect of starch on oral microcosm grown within the dual constant depth film fermenter.

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.

Television advertisements for high-sugar foods and beverages: effect on children's snack food intake.

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.

Fluorescence fingerprints of oral bacteria.

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.

Presenting information on dental risk: PREFER study protocol for a randomised controlled trial involving patients receiving a dental check-up.

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.

Oral care after stroke: Where are we now?

PURPOSE: There appears to be an association between poor oral hygiene and increased risk of aspiration pneumonia - a leading cause of mortality post-stroke. We aim to synthesise what is known about oral care after stroke, identify knowledge gaps and outline priorities for research that will provide evidence to inform best practice. METHODS: A narrative review from a multidisciplinary perspective, drawing on evidence from systematic reviews, literature, expert and lay opinion to scrutinise current practice in oral care after a stroke and seek consensus on research priorities.Findings: Oral care tends to be of poor quality and delegated to the least qualified members of the caring team. Nursing staff often work in a pressured environment where other aspects of clinical care take priority. Guidelines that exist are based on weak evidence and lack detail about how best to provide oral care. DISCUSSION: Oral health after a stroke is important from a social as well as physical health perspective, yet tends to be neglected. Multidisciplinary research is needed to improve understanding of the complexities associated with delivering good oral care for stroke patients. Also to provide the evidence for practice that will improve wellbeing and may reduce risk of aspiration pneumonia and other serious sequelae. CONCLUSION: Although there is evidence of an association, there is only weak evidence about whether improving oral care reduces risk of pneumonia or mortality after a stroke. Clinically relevant, feasible, cost-effective, evidence-based oral care interventions to improve patient outcomes in stroke care are urgently needed.

Oral flora in acute stroke patients: A prospective exploratory observational study.

OBJECTIVE: To describe the bacterial profile of the oral flora during the first 2 weeks following a stroke, examining changes in the condition of the oral cavity and infections. 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. MATERIALS AND METHODS: Seventy-seven participants were recruited over a period of 9 months. Fifty participants had a complete set of swabs from four different oral sites and a saliva sample taken at three time points over a 14-day period. Molecular identification of bacteria was performed on the pooled DNA extracted. 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. CONCLUSIONS: There appears to be huge diversity of bacterial organisms in the oral cavity of stroke patients, and as most phylotypes identified were only found in one or two participants, no particular patterns linked to infection or the condition of the oral cavity could be discerned.

Evidence of an in vitro Coupled Diffusion Mechanism of Lesion Formation within Microcosm Dental Plaque.

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.

Prevention and control of dental caries and periodontal diseases at individual and population level: consensus report of group 3 of joint EFP/ORCA workshop on the boundaries between caries and periodontal diseases.

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.

Quantification of Canine Dental Plaque Using Quantitative Light-Induced Fluorescence.

The aim of this work was to evaluate Quantitative Light-induced Fluorescence (QLF) 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.

Evaluating the effect of local pH on fluorescence emissions from oral bacteria of the genus Prevotella.

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 was <6, 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.

The information filter: how dentists use diet diary information to give patients clear and simple advice.

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.

A Preliminary Study of the Effects of pH upon Fluorescence in Suspensions of Prevotella intermedia.

The quantification of fluorescence in dental plaque is currently being developed as a diagnostic tool to help inform and improve oral health. The oral anaerobe Prevotella intermedia exhibits red fluorescence due to the accumulation of porphyrins. pH affects the fluorescence of abiotic preparations of porphyrins caused by changes in speciation between monomers, higher aggregates and dimers, but this phenomenon has not been demonstrated in bacteria. Fluorescence spectra were obtained from suspensions of P. intermedia that were adjusted to pHs commensurate with the range found within dental plaque. Two fluorescent motifs were identified; 410 nm excitation / 634 nm emission (peak A) and 398 nm excitation / 622 nm emission (peak B). A transition in the fluorescence spectra was observed from peak A to peak B with increasing pH which was also evident as culture age increased from 24 hours to 96 hours. In addition to these 'blue-shifts', the intensity of peak A increased with pH whilst decreasing with culture age from 24 to 96 hours. A bacterium's relationship with the local physiochemical environment at the time of image capture may therefore affect the quantification of dental plaque fluorescence.

Quantitative Light-induced Fluorescence-Digital as an oral hygiene evaluation tool to assess plaque accumulation and enamel demineralization in orthodontics.

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.

In silico analyses of heparin binding proteins expression in human periodontal tissues.

BACKGROUND: Periodontitis is described as a group of inflammatory diseases of the gingiva and supporting structures of the periodontium. The accumulation of plaque bacteria, which include putative periodontal pathogens, is known to initiate the disease but the host immune response is the major contributing factor for destruction of periodontal tissues. Proteins that bind to heparin heparin-binding protein (HBPs) play important roles in health and disease and interact with each other via networks known as 'heparin interactomes'. This study aimed at evaluating published datasets of HBPs and its role in periodontitis. METHODS: To elucidate the role of HBPs in periodontitis, bioinformatics analyses of published data was used. In silico analyses of published datasets were used to construct a putative HBPs interactome using an online database resource, 'STRING' (Search Tool for the Retrieval of Interacting Genes). RESULTS: PubMed searches identified 249 genes that were up regulated and 146 genes that were down regulated in periodontal disease, compared with periodontal disease-free gingival samples. In silico analyses using published datasets revealed 25 up-regulated and 23 down-regulated HBPs in periodontitis. Of these HBPs; chemokines, such as CXCL12 was up regulated where as some of the matrixmetalloproteinases (MMPs; MMP-2 and MMP9) were up-regulated while MMP-14 was down regulated. CONCLUSIONS: The results indicate that HBP analyses will provide multiple targets for the biological mechanisms underlying periodontal disease (such as MMPs, cytokines and chemokines) that will have important clinical implications in the future drug design and management of periodontal disease.

Lethal photosensitisation of Prevotellaceae under anaerobic conditions by their endogenous porphyrins.

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/cm(2)). CONCLUSIONS: Lethal photosensitivity was demonstrated in two species of Prevotella under anaerobic conditions.

Evaluation of the co-existence of the red fluorescent plaque bacteria P. gingivalis with S. gordonii and S. mutans in white spot lesion formation during orthodontic treatment.

BACKGROUND: Early detection of white spot lesions (WSLs) around brackets during orthodontic treatment is important for treatment and prevention. But it is unclear whether red fluorescent plaque (RFP) bacteria Porphyromonas gingivalis and its co-existence with Streptococcus mutans and Streptococcus gordonii has any significant influence on this. Therefore the role of this bacterial co existence and WSLs formation during one year of fixed orthodontic therapy was evaluated. METHODS: Fourteen 12 to 22 year old (mean 15 ± 3 years) consecutive patients attending the University of Liverpool dental hospital were recruited for this study. Quantitative Light-induced Fluorescence (QLF) was used to identify RFP and enamel demineralisation, respectively, on anterior labial surfaces before and after placement of fixed orthodontic appliances. Bacterial composition was determined by denaturing gradient gel electrophoresis (DGGE) following nested PCR amplification of the 16S rRNA V2-V3 hypervariable region. RESULTS: WSLs were recorded on 4.2% of tooth surfaces and WSL development was not associated with RFP bacteria P. gingivalis presence. Differences in RFP bacteria P. gingivalis presence with S. mutans and S. gordonii, were observed before and after appliance placement. Intra subject changes in plaque flora between visits were not significantly associated with WSL development (p > 0.05). However, DGGE profiles indicated that apart from S. mutans, S. gordonii might also have a role in human enamel demineralisation. CONCLUSIONS: Fixed orthodontic brackets in adolescents may play a role in altering bacterial composition around brackets during orthodontic treatment and it is plausible that S. gordonii also have a role in human enamel demineralisation. Combinatorial approach of QLF technology and DGGE may be useful in determining bacterial composition during orthodontic therapy which could inform clinical interventions.

Potential use of gallium-doped phosphate-based glass material for periodontitis treatment.

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.