A randomized clinical study to assess the performance of a marketed denture adhesive in a model of food infiltration in healthy, edentulous adults.

OBJECTIVES: An optimized food infiltration methodology was utilized to assess the objective and subjective efficacy of a marketed denture adhesive regarding denture dislodgment and infiltration and perception of food particles under maxillary and mandibular dentures. A pilot study helped optimize methodologies before the efficacy study. MATERIALS AND METHODS: Participants were healthy adults (n =48 for both studies) with fair- to well-fitting and well-made full maxillary and mandibular dentures. In the pilot, groups were a denture adhesive applied in a conventional dabbed-on pattern, a denture adhesive applied in continuous strips, or no adhesive. In the efficacy study, groups were the Test denture adhesive (continuous strips pattern application) or no adhesive, employed in a crossover design. Food infiltration was investigated through measurement of peanut particle mass retrieved from under each denture (30-32 g chewed). No formal statistical testing was performed in the pilot. Statistical analysis in the efficacy study was performed using analysis of variance. Primary efficacy evaluation was combined peanut particle mass from both dentures. Secondary efficacy evaluations included peanut particle mass under separate dentures, participant-reported denture dislodgements, and awareness/rates of how bothersome peanut particles under dentures were. RESULTS: In the pilot, the median peanut particle mass was lower with either pattern application compared with no adhesive. In the efficacy study, peanut particle mass under combined dentures was lower with than without adhesive (geometric mean [product of values]: 5.56 vs. 29.13 mg) with a between-group geometric mean ratio (adhesive over no adhesive) of 0.19 (95% confidence interval: 0.12, 0.30) favoring the Test adhesive (p < .0001). Similar Test adhesive beneficial outcomes in both studies included significantly fewer denture dislodgements and awareness and how bothersome peanut particles under dentures were. Treatments were generally well-tolerated. CONCLUSIONS: These findings, including reduced peanut particle infiltration, fewer denture dislodgments, and lower ratings of bothersomeness, corroborate those studies investigating the benefits of denture adhesive in preventing food infiltration.

Interdental and subgingival microbiota may affect the tongue microbial ecology and oral malodour in health, gingivitis and periodontitis.

BACKGROUND AND OBJECTIVE: Oral malodour is often observed in gingivitis and chronic periodontitis patients, and the tongue microbiota is thought to play a major role in malodorous gas production, including volatile sulphur compounds (VSCs) such as hydrogen sulphide (H2 S) and methanethiol (CH3 SH). This study aimed to examine the link between the presence of VSCs in mouth air (as a marker of oral malodour) and the oral bacterial ecology in the tongue and periodontal niches of healthy, gingivitis and periodontitis patients. METHODS: Participants were clinically assessed using plaque index, bleeding on probing (BOP) and periodontal probing depths, and VSC concentrations in their oral cavity measured using a portable gas chromatograph. Tongue scrapings, subgingival and interdental plaque were collected from healthy individuals (n = 22), and those with gingivitis (n = 14) or chronic periodontitis (n = 15). The bacterial 16S rRNA gene region V3-V4 in these samples was sequenced, and the sequences were analysed using the minimum entropy decomposition pipeline. RESULTS: Elevated VSC concentrations and CH3 SH:H2 S were observed in periodontitis compared with health. Significant ecological differences were observed in the tongue microbiota of healthy subjects with high plaque scores compared to low plaque scores, suggesting a possible connection between the microbiota of the tongue and the periodontium and that key dysbiotic changes may be initiated in the clinically healthy individuals who have higher dental plaque accumulation. Greater subgingival bacterial diversity was positively associated with H2 S in mouth air. Periodontopathic bacteria known to be prolific VSC producers increased in abundance on the tongue associated with increased bleeding on probing (BOP) and total percentage of periodontal pockets >6 mm, supporting the suggestion that the tongue may become a reservoir for periodontopathogens. CONCLUSION: This study highlights the importance of the periodontal microbiota in malodour and has detected dysbiotic changes in the tongue microbiota in periodontitis.

Efficacy of an Experimental Occlusion Technology Toothpaste in the Relief of Dentinal Hypersensitivity: An 8-week Randomised Controlled Trial.

PURPOSE: A novel anhydrous toothpaste formulation has been developed containing the anti-dentinal hypersensitivity (DH) ingredient stannous fluoride (SnF2). MATERIALS AND METHODS: This randomised, controlled, examiner-blind, parallel-group, stratified (by baseline Schiff sensitivity score) study compared efficacy of an experimental 'Test' toothpaste (n = 67) containing 0.454% SnF2, 0.072% sodium fluoride and 5% sodium tripolyphosphate (all percentages w/w) with a negative 'Control' 0.76% sodium monofluorophosphate toothpaste (n = 68) in relieving DH in healthy Chinese adults. After 4-6 weeks acclimatisation, DH was assessed at baseline and following 4 and 8 weeks' twice-daily brushing by response to evaporative (air) (Schiff sensitivity score) and tactile (Yeaple probe) stimuli. An analysis of covariance model was used (factor: treatment group; covariate: baseline Schiff sensitivity score). RESULTS: Both Test and Control toothpastes statistically significantly reduced Schiff sensitivity score from baseline after 8 weeks' use; the Test toothpaste also statistically significantly reduced the score after 4 weeks' use (all p < 0.001). The Test toothpaste reduction was statistically significantly superior to the Control toothpaste reduction at both timepoints (p < 0.001). Percentage differences in treatment effects between Test and Control groups were 24.1% at 4 weeks and 31.7% at 8 weeks. Tactile threshold scores for both treatments statistically significantly increased from baseline at both timepoints (all p < 0.001); however, there were no statistically significant differences between Test and Control groups. Both toothpastes were well-tolerated with no adverse events reported. CONCLUSION: The Test toothpaste containing 0.454% SnF2 reduced DH statistically significantly more than the Control as evaluated by the Schiff sensitivity score, but not by tactile threshold.

Randomised study of intra-oral kinetics of fluoride-containing toothpastes.

OBJECTIVES: This randomised, controlled, analyst blind, crossover study aimed to evaluate and compare salivary fluoride and calcium ion concentration over 60 min following brushing with an assigned treatment and following an orange juice (OJ) or deionised (DI) water rinse 60 min post-brushing. METHODS: Study treatments, both containing 1150 ppm fluoride as NaF and 5% w/w KNO3, were the Test (including 1.2 % w/w cocamidopropyl betaine) and Comparator (including tetrasodium pyrophosphate and sodium lauryl sulphate) toothpastes. Twenty nine participants were randomised to treatment. RESULTS: A sharp increase in salivary fluoride ion concentration immediately post-brushing with either toothpaste decreased over time. Fluoride concentration following Test toothpaste use was numerically higher than the Comparator at all timepoints, with a significant difference from 10 min post-brushing (p < .05). Following the 60 min rinse, there were no significant differences between the Test or Comparator + OJ groups in salivary fluoride concentration but the Test + DI water group was significantly lower than Test (p < .001) or Comparator (p < .001) + OJ groups. A reduction in salivary calcium ion concentration was seen immediately post-brushing and after the OJ rinse with both toothpastes. Significant differences were observed in favour of the Test toothpaste at all timepoints (p < .05) and for Test and Comparator + OJ group (p < .001) compared with Test + DI water rinse. Both treatments were generally well-tolerated. CONCLUSIONS: This study demonstrated that toothpaste formulations with identical declared fluoride concentrations and the same fluoride source give rise to differing intraoral fluoride concentrations over time, which are potentially related to different formulation excipient effects. CLINICAL SIGNIFICANCE: By understanding the interaction of toothpaste formulation excipients in the oral environment, formulations can be developed that maximise retention of fluoride in the oral environment.

In situ efficacy of an experimental toothpaste on enamel rehardening and prevention of demineralisation: a randomised, controlled trial.

BACKGROUND: A novel sodium fluoride toothpaste containing lactate ion and polyvinylmethylether-maleic anhydride has been developed to promote enamel remineralisation and resistance to demineralisation. In this in situ study, we compared this toothpaste ('Test') with a stannous fluoride-zinc citrate (SnF2-Zn) toothpaste ('Reference') (both 1100-1150 ppm fluoride) and a fluoride-free toothpaste ('Placebo') using an enamel dental erosion-rehardening model. METHODS: In each phase of this randomised, investigator-blind, crossover study, participants wore palatal appliances holding bovine enamel specimens with erosive lesions. They brushed their natural teeth with either the Test, Reference or Placebo toothpastes, then swished the resultant slurry. Specimens were removed at 2 h and 4 h post-brushing and exposed to an in vitro acid challenge. Surface microhardness was measured at each stage; enamel fluoride uptake was measured after in situ rehardening. Surface microhardness recovery, relative erosion resistance, enamel fluoride uptake and acid resistance ratio were calculated at both timepoints. RESULTS: Sixty two randomised participants completed the study. Test toothpaste treatment yielded significantly greater surface microhardness recovery, relative erosion resistance and enamel fluoride uptake values than either Reference or Placebo toothpastes after 2 and 4 h. The acid resistance ratio value for Test toothpaste was significantly greater than either of the other treatments after 2 h; after 4 h, it was significantly greater versus Placebo only. No treatment-related adverse events were reported. CONCLUSIONS: In this in situ model, the novel-formulation sodium fluoride toothpaste enhanced enamel rehardening and overall protection against demineralisation compared with a fluoride-free toothpaste and a marketed SnF2-Zn toothpaste. TRIAL REGISTRATION: ClinicalTrials.gov; NCT03296072; registered September 28, 2017.

Impact of toothpaste on oral health-related quality of life in people with dentine hypersensitivity.

BACKGROUND: Dentine hypersensitivity can impact functional status and everyday activities such as eating and talking. This study aimed to assess changes in oral health-related quality of life measures in individuals with dentine hypersensitivity following long-term use (24 weeks) of a commercially available toothpaste marketed for dentine hypersensitivity relief. METHODS: This study was conducted across two sites and enrolled 75 adults with ≥2 non-adjacent sensitive teeth. Participants were assigned to twice-daily brushing with toothpaste containing 0.454% w/w stannous fluoride (1100 ppm fluoride). Every 4 weeks, participant-reported outcomes were assessed using the Dentine Hypersensitivity Experience Questionnaire (DHEQ), a condition specific oral health-related quality of life scale that has five domains and includes questions on social and emotional impact, restrictions, adaptations and effect on life overall. Responses to a clinically applied evaporative (air) stimulus were assessed using the examiner-observed Schiff sensitivity scale and Labelled Magnitude Scales (LMS), which included dentine hypersensitivity-specific descriptors of intensity, duration, tolerability and descriptive qualities of the participant's response. RESULTS: Participant-reported outcomes demonstrated reduction of the impact of dentine hypersensitivity over time on health-related quality of life, as measured by the DHEQ. This reached statistical significance from Week 8 onwards (p < 0.0001 versus baseline) for the Total DHEQ score, with scores continually decreasing at each timepoint. Most domain scores followed a similar pattern. Statistically significant reductions were also detected for the examiner-observed Schiff Sensitivity Scale scores at all timepoints (including at 4 weeks) (p < 0.05), which were mirrored by LMS responses. The toothpaste was generally well-tolerated. CONCLUSIONS: These results show that long-term use of a sensitivity toothpaste containing 0.454% w/w stannous fluoride has a beneficial, ongoing, impact on the oral health-related quality of life of people with dentine hypersensitivity. TRIAL REGISTRATION: This study was registered at Clinicaltrials.gov ( https://clinicaltrials.gov/ct2/show/NCT02752958 ) on April 27, 2016.

A randomized clinical study to evaluate the effect of denture adhesive application technique on food particle accumulation under dentures.

Food ingress under dentures is a common problem that may be reduced by denture adhesive use. The objective of this study was to explore the effect of the mode of application of a denture adhesive on reducing accumulation of food particles under dentures. This was a single-centre, controlled, single-blind, randomized, three-treatment, three-period, crossover study in participants with complete, removable well-fitting, well-made upper/lower dentures. Treatments were: 1) experimental denture adhesive application (test adhesive) applied with a precision applicator as continuous strips; 2) marketed denture adhesive (positive control) applied using a flat ribbon nozzle as dabs; 3) no adhesive. Food-occlusion testing was performed by assessing peanut particle migration under dentures with denture retention/stability evaluated using the Kapur Index (Olshan modification). Differences were assessed using an ANOVA model. Adhesive oozing and perceptions of the adhesives were assessed by questionnaire. All 83 randomized participants completed the study. There were no significant differences between positive control or test adhesives versus no adhesive, or between test adhesive and positive control, for mass of peanut particles recovered from dentures. Both adhesives had significantly higher retention and stability scores compared with no adhesive (all P < .01). Participants reported significantly higher scores for denture comfort, confidence, satisfaction and movement with both adhesives versus no adhesive (all P < .01). No differences in adhesive ooze were reported between adhesives. No adverse events were reported. In conclusion, there was no difference in performance, as measured by peanut particle mass recovered from upper/lower dentures, for the test adhesive, positive control and no adhesive.

A randomised bite force study assessing two currently marketed denture adhesive products compared with no-adhesive control.

Unlike other oral care products, there are limited technologies in the denture adhesive category with the majority based on polymethyl vinyl ether/maleic anhydride (PVM/MA) polymer. Carbomer-based denture adhesives are less well studied, and there are few clinical studies directly comparing performance of denture adhesives based on different technologies. This single-centre, randomised, three-treatment, three-period, examiner-blind, crossover study compared a carbomer-based denture adhesive (Test adhesive) with a PVM/MA-based adhesive (Reference adhesive) and no adhesive using incisal bite force measurements (area over baseline over 12 hr; AOB0-12) in participants with a well-made and at least moderately well-fitting complete maxillary denture. Eligible participants were randomised to a treatment sequence and bit on a force transducer with increasing force until their maxillary denture dislodged. This procedure was performed prior to treatment application (baseline) and at 0.5, 1, 3, 6, 9, and 12 hr following application. Forty-four participants were included in the modified intent-to-treat population. AOB0-12 favoured both Test adhesive to No adhesive (difference: 2.12 lbs; 95% CI [1.25, 3.00]; p < 0.0001) and Reference adhesive to No adhesive (difference: 2.76 lbs; 95% CI [1.89, 3.63]; p < 0.0001). There was a numerical difference in AOB0-12 for Test versus Reference adhesive (-0.63 lbs; [-1.51, 0.25]); however, this was not statistically significant (p = 0.1555). Treatments were generally well tolerated. Both PVM/MA and carbomer-based denture adhesives demonstrated statistically significantly superior denture retention compared with no adhesive over 12 hr, with no statistically significant difference between adhesives.

Randomized Controlled Clinical Study to Determine the Oral and Dermal Tolerability of an Experimental Denture Wipe.

PURPOSE: To evaluate oral and dermal tolerance following use and user acceptability of an experimental denture-cleansing wipe. An exploratory objective was to develop a method to assess denture wipe effectiveness in removing debris from denture surfaces. MATERIALS AND METHODS: This was a single-center, randomized, controlled, parallel-group, examiner-blind study in participants with ≥1 full/partial denture. Participants were randomized to clean their dentures with the denture wipe (n = 76) or water (n = 76) up to 4 times per day for 14 days. Tolerability was assessed by treatment-emergent adverse events (TEAEs), oral soft tissue examination, and lead hand dermatological assessment. Acceptability was assessed by questionnaire. The feasibility of a methodology to assess the efficacy of the wipe at removing food particles was also evaluated through determination of the mass of chewed peanut particles that the wipe removed after a single use (n = 31). RESULTS: The proportion of participants experiencing oral TEAEs by day 14 was 0.039% with the denture wipe (lip injury [n = 1], mouth injury [n = 2]) and 0.013% with the water rinse (coated tongue [n = 1]). There were no dermal TEAEs and no TEAE-related study withdrawals. Skin irritation scores with the denture wipe remained unchanged from baseline. Comparing before vs. after cleaning with the denture wipe, a higher proportion of participants rated their dentures as feeling extremely/very fresh (28.9% pre-/85.5% post-cleaning), feeling extremely/very clean (34.2%/86.8%) and looking extremely/very clean (43.5%/85.5%). More denture-wipe group participants than water-rinse group participants were extremely/very satisfied with the amount of debris removed from their dentures (88.1% vs 72.4%). The methodology used to assess the weight of peanut particles captured from the wipes/dentures appeared to be a feasible investigation technique. CONCLUSIONS: The denture wipe was generally well-tolerated and had good user acceptability. The methodology for assessing the mass of peanut particles removed by denture wipes was successful.

Randomized exploratory study to measure ion release from calcium sodium phosphosilicate-containing dentifrice.

This exploratory study investigated salivary concentrations of silicon, calcium, sodium, and phosphorous over a 60-min time period following the use of a calcium sodium phosphosilicate (CSPS)-containing dentifrice. Participants brushed with a dentifrice containing 5% (w/w) or 0% (w/w) CSPS or swilled with a slurry containing 5% (w/w) CSPS/glycerol. Saliva samples were collected before, and 2, 5, 15, and 60 min after, product use and were analysed using inductively coupled plasma optical emission spectroscopy. Intra-oral pH measurements were also taken. Primary analysis was of centrifuged saliva supernatant containing only dissolved material. At most time points, the CSPS-containing dentifrice and slurry generated significantly more salivary silicon than the dentifrice containing 0% CSPS. At 2-15 min after brushing there was significantly more salivary calcium after use of the CSPS-containing dentifrice and slurry, compared with the 0% CSPS dentifrice; a significant reduction, from baseline, in salivary calcium after use of dentifrice containing 0% CSPS; and an increase in salivary sodium after use of dentifrices containing either 5% or 0% CSPS, but no differences between them. Salivary phosphorous concentration decreased significantly with all treatments 2-5 min after use. There were no significant between-treatment differences in intra-oral pH. Products were generally well tolerated. This study establishes that it is possible to measure changes in salivary ionic composition derived through oral retention of CSPS, delivered via a dentifrice.

Effect of phytate and zinc ions on fluoride toothpaste efficacy using an in situ caries model.

OBJECTIVES: To compare and explore the dose-response of phytate-containing 1150 ppm fluoride toothpastes on model caries lesions and to determine the impact of zinc ions. METHODS: This was a single-centre, randomised, blinded (examiner/laboratory analyst), six-treatment, four-period crossover, in situ study in adults with a removable bilateral maxillary partial denture. Study treatments were toothpastes containing: 0.425% phytate/F; 0.85% phytate/F; 0.85% phytate/Zn/F; F-only; Zn/F and a 0% F placebo. Where present, F was 1150 ppm as NaF; Zn was 0.3% as ZnCl2. Human enamel specimens containing early-stage, surface-softened (A-lesions) or more advanced, subsurface (B-lesions) caries lesions were placed into the buccal flanges of participants' modified partial denture (one of each lesion type per side). A-lesions were removed after 14 days of twice-daily treatment use; B-lesions were removed after a further 14 days. A-lesions were analysed for surface microhardness recovery. Both lesion types were analysed by transverse microradiography and for enamel fluoride uptake, with B-lesions additionally analysed by quantitative light-induced fluorescence. Comparison was carried out using an analysis of covariance model. RESULTS: Statistically significant differences between 1150 ppm F and the placebo toothpastes (p < 0.05) were shown for all measures, validating the model. No differences between fluoride toothpastes were observed for any measure with little evidence of a dose-response for phytate. Study treatments were generally well-tolerated. CONCLUSIONS: Results suggest phytate has little impact on fluoride's ability to promote early-stage lesion remineralisation or prevent more advanced lesion demineralisation in this in situ caries model. Similarly, results suggest zinc ions do not impair fluoride efficacy. CLINICAL SIGNIFICANCE: Toothpastes may contain therapeutic or cosmetic agents that could interfere with fluoride's caries prevention efficacy. The present in situ caries study has demonstrated that phytate, added to provide enhanced extrinsic stain removal/prevention, and zinc, added to inhibit malodour, do not impair fluoride efficacy.

Effects of a sodium fluoride- and phytate-containing dentifrice on remineralisation of enamel erosive lesions-an in situ randomised clinical study.

OBJECTIVE: The objective of this work was to evaluate effects of a dentifrice containing sodium fluoride (1150 ppm F) and the organic polyphosphate phytate (0.85% w/w of the hexa-sodium salt) on in situ remineralisation of early enamel erosive lesions and resistance to subsequent demineralisation. MATERIALS AND METHODS: Subjects (n = 62) wore palatal appliances holding eight bovine enamel specimens with pre-formed erosive lesions. They brushed their natural teeth with the phytate test dentifrice (TD); a positive control dentifrice (PC, 1150 ppm fluoride as NaF); a reference dentifrice (RD, disodium pyrophosphate + 1100 ppm fluoride as NaF) or a negative control dentifrice (NC, fluoride-free) in a randomised, double-blind, crossover design. Specimens were removed at 2, 4 and 8 h post-brushing and exposed to an ex vivo acid challenge. Surface microhardness (Knoop) was measured at each stage. The primary efficacy variable was relative erosion resistance (RER); other variables included the surface microhardness recovery (SMHR), acid resistance ratio (ARR) and enamel fluoride uptake (EFU). RESULTS: After 4 h, the results for RER, ARR and EFU were in the order PC > TD = RD > NC with PC > TD = RD = NC for SMHR. Results at 2 and 8 h were generally consistent with the 4 h data. Mineralisation progressed over time. Dentifrices were generally well-tolerated. CONCLUSIONS: In this in situ model, addition of phytate or pyrophosphate to a fluoride dentifrice inhibited the remineralising effect of fluoride. Both formulations still delivered fluoride to the enamel and inhibited demineralisation, albeit to a lesser extent than a polyphosphate-free dentifrice. CLINICAL RELEVANCE: Addition of phytate or pyrophosphate to a fluoride dentifrice may reduce its net anti-erosive properties.

A randomized clinical trial to evaluate the stain removal efficacy of a sodium phytate dentifrice formulation.

OBJECTIVES: Phytate is an organic, cyclic polyphosphate analogous to linear condensed polyphosphates used as stain removal agents. This study investigated stain removal efficacy of an experimental sodium phytate-containing dentifrice compared to a reference dentifrice. METHODS: An experimental, moderate abrasivity (relative dentine abrasivity [RDA] âˆ¼130) antisensitivity fluoride dentifrice containing sodium phytate (0.85% w/w as the hexasodium salt) (n = 111) was compared to a reference, marketed, low-abrasivity (RDA âˆ¼ 43), anti-sensitivity fluoride dentifrice (n = 113), both containing 1150 ppm fluoride as sodium fluoride. Primary efficacy variables were between-treatment differences in extrinsic dental stain of anterior teeth after 6 and 12 weeks' twice-daily use, using Lobene stain index (MacPherson modification, MLSI) mean area (A) and intensity (I) scores. Comparisons included whole-tooth and hard-to-reach areas (gingival, interproximal, body of lingual). RESULTS: At both 6- and 12-week timepoints, MLSI (A × I) scores for total area and hard-to-reach areas for the experimental dentifrice were statistically significantly lower than baseline (P < .0001 for all). This was demonstrated for the reference dentifrice at 6 weeks only, for total, interproximal (P < .0001 for both), and body of lingual (P = .0395) scores. Compared with the reference, the experimental dentifrice had statistically significantly lower MLSI scores at both 6 and 12 weeks for all outcome variables including both total MLSI (A × I) and hard-to reach areas (P < .0001 in all cases). Products were generally well-tolerated. CONCLUSIONS: Differences between treatments were considered clinically differentiable. Sodium phytate may therefore be a suitable additive ingredient to improve tooth stain control performance within an otherwise conventional dentifrice formulation. CLINICAL SIGNIFICANCE: Following 6 and 12 weeks brushing, clinically differentiable differences were shown in stain index scores with an experimental dentifrice containing sodium phytate compared to a reference dentifrice without sodium phytate. Sodium phytate may therefore be a suitable additive ingredient to improve tooth stain control performance within an otherwise conventional dentifrice formulation.

Potassium oxalate oral rinses for long-term relief from dentinal hypersensitivity: Three randomised controlled studies.

OBJECTIVES: To evaluate effectiveness of oral rinses containing dipotassium oxalate monohydrate (KOX) in relieving dentinal hypersensitivity (DH) after 8 w use adjunctive to brushing. METHODS: Three 8-week, randomised, controlled, double-blind, parallel-group, single-centre studies were conducted in adults with DH. In each study, participants were randomised to one of two experimental rinses or a placebo in a matrix design, such that each experimental rinse was evaluated in two studies. Rinses A (pH 4.5) and B (pH 7.0) contained 1.5% KOX and were fluoride-free; Rinse C (pH 4.5) contained 2.0% KOX and 45 ppm fluoride as NaF; the placebo rinse (pH 4.5) did not contain KOX or fluoride. Participants brushed with a fluoride dentifrice for 1 min, briefly rinsed with water, then rinsed with their assigned oral rinse for 1 min twice daily for 8 w. DH was assessed at baseline and following 4 and 8 w use by response to an evaporative (air) stimulus (evaluated by Schiff sensitivity score and a 10-point visual rating scale) and a tactile stimulus (Yeaple probe). RESULTS: All rinses in each study were associated with statistically significant improvements from baseline in measures of DH after 4 and 8 w treatment. However, between-treatment comparisons were inconsistent across the studies, with only Study 3 demonstrating a significant difference between the experimental (Rinses B and C) and placebo rinses. A number of treatment-related adverse events (all mild) were reported. CONCLUSIONS: Rinses containing 1.5-2.0% KOX did not consistently demonstrate a benefit over placebo in relieving DH after 8 w use. CLINICAL SIGNIFICANCE: While favourable results were found in one of the investigations, this suite of studies shows that the possibility of inconsistent results exists even with the best designed and executed trials.

Longitudinal correlation of 3D OCT to detect early stage erosion in bovine enamel.

Erosive tissue-loss in dental enamel is of significant clinical concern because the net loss of enamel is irreversible, however, initial erosion is reversible. Micro-hardness testing is a standard method for measuring initial erosion, but its invasive nature has led to the investigation of alternative measurement techniques. Optical coherence tomography (OCT) is an attractive alternative because of its ability to non-invasively image three-dimensional volumes. In this study, a four-dimensional OCT system is used to longitudinally measure bovine enamel undergoing a continuous erosive challenge. A new method of analyzing 3D OCT volumes is introduced that compares intensity projections of the specimen surface by calculating the slope of a linear regression line between corresponding pixel intensities and the associated correlation coefficient. The OCT correlation measurements are compared to micro-hardness data and found to exhibit a linear relationship. The results show that this method is a sensitive technique for the investigation of the formation of early stage erosive lesions.

In Vitro Effect of Porphyromonas gingivalis Methionine Gamma Lyase on Biofilm Composition and Oral Inflammatory Response.

Methanethiol (methyl mercaptan) is an important contributor to oral malodour and periodontal tissue destruction. Porphyromonas gingivalis, Prevotella intermedia and Fusobacterium nucleatum are key oral microbial species that produce methanethiol via methionine gamma lyase (mgl) activity. The aim of this study was to compare an mgl knockout strain of P. gingivalis with its wild type using a 10-species biofilm co-culture model with oral keratinocytes and its effect on biofilm composition and inflammatory cytokine production. A P. gingivalis mgl knockout strain was constructed using insertion mutagenesis from wild type W50 with gas chromatographic head space analysis confirming lack of methanethiol production. 10-species biofilms consisting of Streptococcus mitis, Streptococcus oralis, Streptococcus intermedius, Fusobacterium nucleatum ssp polymorphum, Fusobacterium nucleatum ssp vincentii, Veillonella dispar, Actinomyces naeslundii, Prevotella intermedia and Aggregatibacter actinomycetemcomitans with either the wild type or mutant P. gingivalis were grown on Thermanox cover slips and used to stimulate oral keratinocytes (OKF6-TERT2), under anaerobic conditions for 4 and 24 hours. Biofilms were analysed by quantitative PCR with SYBR Green for changes in microbial ecology. Keratinocyte culture supernatants were analysed using a multiplex bead immunoassay for cytokines. Significant population differences were observed between mutant and wild type biofilms; V. dispar proportions increased (p<0.001), whilst A. naeslundii (p<0.01) and Streptococcus spp. (p<0.05) decreased in mutant biofilms. Keratinocytes produced less IL-8, IL-6 and IL-1α when stimulated with the mutant biofilms compared to wild type. Lack of mgl in P. gingivalis has been shown to affect microbial ecology in vitro, giving rise to a markedly different biofilm composition, with a more pro-inflammatory cytokine response from the keratinocytes observed. A possible role for methanethiol in biofilm formation and cytokine response with subsequent effects on oral malodor and periodontitis is suggested.

Structural and compositional changes in the salivary pellicle induced upon exposure to SDS and STP.

Sodium dodecyl sulphate (SDS) and sodium tripolyphosphate (STP) act to remove stained pellicle from dentition and loosen deposits on tooth surfaces that may become cariogenic over time. This study investigated how SDS and STP impact the salivary pellicle adsorbed onto hydroxyapatite and silica sensors using a dual polarisation interferometer and a quartz-crystal microbalance with dissipation. After the pellicle was exposed to SDS and STP the remaining pellicle, although weaker, due to the loss of material, became less dense but with a higher elastic component; suggesting that the viscous component of the pellicle was being removed. This would imply a structural transformation from a soft but dense structured pellicle, to a more diffuse pellicle. In addition, the majority of proteins displaced by both SDS and STP were identified as being acidic in nature; implying that the negatively charged groups of SDS and STP may be responsible for the displacement of the pellicle proteins observed.

In vitro growth characteristics and volatile sulfur compound production of Solobacterium moorei.

Solobacterium moorei has recently been implicated as a causative agent of halitosis. In vitro experiments to evaluate the role of S. moorei in halitosis have, however, been complicated by a paucity of information on the ideal conditions for culturing this organism. This work aimed to optimize a liquid culture medium for S. moorei, and to determine the growth-curve of the organism. Further, the ability of S. moorei to generate volatile sulfur compounds was investigated and compared quantitatively to other oral anaerobes by an optimized head-space gas chromatography method. Serum-supplementation of standard liquid growth media gave greater growth of S. moorei than non-supplemented broths, with the best medium found to be serum-supplemented tryptone soya broth. S. moorei was able to metabolize cysteine directly to hydrogen sulfide, but was unable to produce methanethiol from methionine. S. moorei produced 2-3 times more hydrogen sulfide (normalized for colony forming units) than Porphyromonas gingivalis and Veillonella dispar, but considerably less than Fusobacterium nucleatum. The study has identified reliable growth conditions for culture of S. moorei, which were employed to show that S. moorei has the requisite biochemistry consistent with a potential role in halitosis.

Structural characterisation of parotid and whole mouth salivary pellicles adsorbed onto DPI and QCMD hydroxyapatite sensors.

In this study we investigated the differences in the properties of pellicles formed from stimulated parotid saliva (PS), which contains little or no mucin; and stimulated whole mouth saliva (WMS), which contains mainly two types of mucin: MUC5B and MUC7. By contacting WMS and PS with quartz-crystal microbalance with dissipation monitoring (QCM-D) and dual polarisation interferometer (DPI) hydroxyapatite (the main component of enamel) coated sensors, we observed the formation and structure of the respective salivary pellicles. As this was the first time that DPI hydroxyapatite sensors have been used to measure salivary pellicle adsorption; the techniques combined allowed us to measure the hydrated mass, dry mass, thickness and viscoelastic properties of the pellicle; but also to record the density of the PS and WMS formed pellicles. Subsequently, the PS pellicle was shown to form a denser layer than WMS pellicle; which would suggest that the proteins present in PS are also responsible for forming the dense basal layer of the acquired enamel pellicle. Whereas proteins present in the WMS are more likely to help form the softer outer layer of the pellicle. The data presented help to further define the mechanisms leading to the multi-layered structure of the salivary pellicle and demonstrate that salivary composition has an important effect on the structural properties of the adsorbed pellicle.

In vitro studies investigating the dentin tubule-occlusion properties of an experimental anhydrous stannous fluoride dentifrice.

PURPOSE: To evaluate in vitro the ability for an experimental anhydrous 0.454% w/w stannous fluoride dentifrice to occlude dentin tubules. METHODS: Scanning electron microscopy (SEM) was used to assess tubule occlusion and the resistance of the occlusion to dietary acid in a 4-day model, where bovine dentin was treated with product twice daily with acid challenges administered on Days 3 and 4. The reduction in hydraulic conductance of the dentin following treatment was also measured. RESULTS: The experimental stannous fluoride dentifrice was effective at reducing the hydraulic conductance of dentin by occluding tubules. The occlusion was resistant to challenge with grapefruit juice.