Fluoride content of tank water in Australia.

BACKGROUND: The aims of this study were to: (1) analyse the fluoride content of tank water; (2) determine whether the method of water collection or storage influenced fluoride content; and (3) survey participant attitudes towards water fluoridation. METHODS: Plastic tubes and a questionnaire were distributed through dentists to households with water tanks in Victoria. A midstream tank water sample was collected and fluoride analysed in triplicate using ion chromatography RESULTS: All samples (n = 123) contained negligible amounts of fluoride, with a mean fluoride concentration of <0.01 ppm (range: <0.01-0.18 ppm). No statistically significant association was found between fluoride content and variables investigated such as tank material, tank age, roof material and gutter material. Most people did not know whether their tank water contained fluoride and 40.8% preferred to have access to fluoridated water. The majority thought fluoride was safe and more than half of the respondents supported fluoridation. Fluoride content of tank water was well below the optimal levels for caries prevention. CONCLUSIONS: People who rely solely on tank water for drinking may require additional exposure to fluoride for optimal caries prevention.

Ion release from calcium and fluoride containing dental varnishes.

BACKGROUND: A range of dental varnishes have been commercialized recently that contain calcium and inorganic phosphate in addition to fluoride. The aim of this study was to analyse the fluoride, calcium and inorganic phosphate ion release from: (1) MI Varnish containing casein phosphopeptide-amorphous calcium phosphate (CPP-ACP); (2) Clinpro White containing functionalized tricalcium phosphate (fTCP); (3) Enamel Pro containing amorphous calcium phosphate; (4) Bifluorid 5 containing calcium fluoride; and (5) Duraphat (no added calcium control). METHODS: The varnishes were applied to a standardized surface area of polyvinyl chloride (n = 7 per group) and immersed in 25 g of distilled deionized water which was changed at 1, 4, 24, 72 and 168 hours. The ion release was determined by ion chromatography and expressed as µmol (cumulative) per gram of varnish. RESULTS: All varnishes released measurable fluoride and calcium, however only MI Varnish and Enamel Pro released significant levels of inorganic phosphate. At 24 hours the order of cumulative fluoride release was: 1>3>4>2=5 with 1 significantly higher (p < 0.05) than the rest. At 72 and 168 hours, the cumulative calcium release was: 1>4>3>2=5 with 1 significantly higher (p < 0.05) than the rest. CONCLUSIONS: MI Varnish containing CPP-ACP had the highest release of calcium and fluoride ions.

Ion release and physical properties of CPP-ACP modified GIC in acid solutions.

A new glass-ionomer cement (GIC) (Fuji VII™ EP) includes 3% (w/w) casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) to enhance ion release. OBJECTIVES: To assess this new GIC compared with a GIC without CPP-ACP (Fuji VII™) with respect to ion release, changes in surface hardness and in mass under a variety of acidic and neutral conditions. METHODS: Eighty blocks of Fuji VII™ (F7) and Fuji VII™ EP (F7EP) were subjected to three acidic solutions (lactic and citric acids pH 5.0, hydrochloric acid pH 2.0) and water (pH 6.9) over a three-day period. Ion release, surface hardness and weight measurements were carried out every 24h. RESULTS: Higher calcium ion release from F7EP was observed under all acidic conditions. Increased inorganic phosphate ion release was observed for F7EP in hydrochloric and citric acids. Fluoride ion release was similar between F7 and F7EP under all conditions but was significantly higher in acids compared with water. After three days there was no significant difference in surface hardness (p>0.05) between the two materials under all conditions except hydrochloric acid. Minimal change in mass was observed for F7 and F7EP in water, lactic and hydrochloric acids, however citric acid caused significantly more mass loss compared with water (p<0.001). CONCLUSION: Incorporation of 3% (w/w) CPP-ACP into F7 enhanced calcium and phosphate ion release, with no significant change in fluoride ion release and no adverse effects on surface hardness or change in mass. CLINICAL SIGNIFICANCE STATEMENT: GICs have the potential to release fluoride ions particularly under acidic conditions associated with dental caries and erosion. A new GIC containing CPP-ACP and fluoride releases not only fluoride ions but also calcium and phosphate ions under acidic conditions which should help to inhibit demineralisation associated with caries and erosion.

Mineralisation of developmentally hypomineralised human enamel in vitro.

Molar-incisor hypomineralisation (MIH) is a problematic and costly condition. Caries remineralising agents are often recommended for MIH management despite the lack of evidence that these lesions have the capacity for increasing their mineral content. Following surface layer removal ± NaOCl pre-treatment and 14-day exposure to a CPP-ACFP solution at pH 5.5, MIH lesions were analysed using transverse microradiography and polarised light microscopy. Lesions were highly variable but treatment with the remineralising solution increased mineral content (1,828 ± 461 vol% min · µm, %R = 17.7 ± 5.7) and porosity decreased demonstrating the proof of concept that the mineral content of developmentally hypomineralised enamel can be improved after eruption.

Comparison of quantitative light-induced fluorescence, digital photography and transverse microradiography for quantification of enamel remineralization.

BACKGROUND: Quantitative light-induced fluorescence (QLF) and digital photography (DP) have been proposed as clinical methods for measuring changes in enamel mineral content. The aim of this study was to compare the ability of QLF and DP with the in vitro gold standard transverse microradiography (TMR) to measure the remineralization of enamel subsurface lesions. METHODS: Subsurface lesions were formed in enamel (n = 40) and exposed to remineralization solutions for 10 days. Changes were analysed by DP, QLF and TMR to determine percentage changes in luminescence (%L), fluorescence (%F) and mineral content (%R), respectively and correlation between these parameters determined. RESULTS: The correlations between TMR and QLF (r = 0.63), TMR and DP (r = 0.59), and DP and QLF (r = 0.64) were all moderate but statistically significant (p < 0.001). The variability in %L and, to a lesser extent, %F values significantly impacted on the potential role of DP and QLF as methods by which mineral content changes produced by remineralization treatments could be accurately measured. CONCLUSIONS: Both QLF and DP provided data that correlated moderately with TMR data. QLF images were easier to analyse, free of glare and had less variability compared with those produced using DP.

Effect of different orthodontic adhesive removal techniques on sound, demineralized and remineralized enamel.

BACKGROUND: The aim of this in vitro study was to determine the effect of four different orthodontic adhesive removal techniques on sound, demineralized and remineralized enamel. METHODS: Composite resin adhesive was bonded to 100 teeth which were divided into four groups with each comprising five sound teeth and 20 teeth with demineralized and remineralized lesions adjacent to the adhesive. Adhesive was removed with either: (1) slow speed bur (SS); (2) high speed bur (HS); (3) aluminium oxide disc (DC); or (4) ultrasonic scaler (US). Damage to the enamel was assessed using white light profilometry, digital photography and scanning electron microscopy. RESULTS: The least to greatest mean depth of damage with the four different adhesive removal techniques to sound enamel was DC = SS < US = HS and to demineralized and remineralized enamel were DC < HS < US = SS. Sound enamel experienced the least amount of damage. Remineralization prior to adhesive removal significantly reduced the amount of damage produced by all techniques compared with demineralized enamel. Discs were the least damaging to demineralized and remineralized enamel compared with the other removal techniques. CONCLUSIONS: When demineralization was present discs were found to be the least damaging adhesive removal technique and remineralization further reduced the amount of enamel damage.

Erosive potential of sports beverages.

BACKGROUND: Dental erosion is an increasingly prevalent problem in Australia, with the consumption of sports beverages suggested as a risk factor. The aim of this study was to compare the erosive potential of Australian sports beverages. METHODS: Ten beverages were selected and analysed to determine their pH, titratable acidity and apparent degree of saturation with respect to apatite. The erosive potential of the beverages was measured by human enamel surface loss and surface softening following a 30-minute exposure. A taste testing panel was established to determine the palatability of the sports beverages. RESULTS: All sports beverages except Sukkie and Endura produced substantial surface loss and surface softening. Compared with the other sports beverages, Sukkie and Endura had a higher pH, lower titratable acidity and higher calcium content. However, Sukkie and Endura were deemed to be less palatable than the other more acidic sports beverages. CONCLUSIONS: The majority of the sports beverages tested produced dental erosion in this in vitro model. However, two new products Sukkie and Endura have lower erosive potential but also lower palatability.

Calcium phosphopeptides -- mechanisms of action and evidence for clinical efficacy.

Phosphoproteins/phosphopeptides with clusters of acidic residues are found throughout nature, where they aid in the prevention of unwanted precipitation of solid calcium phosphates. The acidic residues, particularly phosphoserine, interact with calcium and stabilize clusters of calcium and phosphate. Saliva and milk are two examples of biological fluids that contain such phosphoprotein/phosphopeptide-stabilized calcium phosphates, and both share a similar evolutionary pathway. Saliva has been shown to have remineralization potential and is of critical importance in maintaining the mineral content of teeth in the oral environment. Milk can be enzymatically modified to release casein phosphopeptides that contain the clusters of residues that allow milk to stabilize high concentrations of calcium and phosphate. These casein phosphopeptide-stabilized amorphous calcium phosphate nanocomplexes (CPP-ACP) can stabilize even higher concentrations of calcium and phosphate than milk and can be considered a salivary biomimetic, since they share many similarities to statherin. The mechanisms of action and the growing body of scientific evidence that supports the use of CPP-ACP to augment fluoride in inhibiting demineralization and enhancing the remineralization of white-spot lesions are reviewed.

Remineralization models.

During the ICNARA 2 conference, a workshop was held on remineralization models. The group considered the role of remineralization models, whether there was one ideal in situ model design, what essential features should be incorporated into an in situ model, other alternative models, and what new methods for measuring remineralization were on the horizon. This paper summarizes the discussion. In situ and other caries models can be used as a surrogate for caries clinical trials but only when data exist to validate the model. In situ model design should be flexible to allow for investigation of different aspects of the caries process; however, several essential features were identified that should be incorporated into the study design. A range of other caries models was discussed, including the study of non-cavitated lesions, lesions post-orthodontic therapy, plaque retention models to form more standardized lesions, and the study of root caries lesions. Numerous new methods for quantifying remineralization were discussed, but it was considered that these require validation before they can be used in clinical trials.

A comparative study of carbonate determination in human teeth using Raman spectroscopy.

Carbonate determination in dental apatites such as dentine and enamel is important for studying the dynamics of dental caries and developmental defects of these tissues. Traditionally, these determinations have been performed by acidic digestion with the subsequent measurement of released carbon dioxide gas. As an alternative, Raman spectroscopy has been used for the determination of carbonate in synthetic carbonated apatites with at least four analytical methods published thus far. However, these methods have not been applied to biological apatites. The aim of this comparative study was to test the suitability of these four methods for the determination of B-type carbonate in human enamel and dentine. A method for determining the A-type carbonate content of enamel using the Raman technique is also presented. Raman spectra were obtained from 10 human enamel and dentine samples and analysed with each of the four methods using either a single or multiple ν(1)(PO(4)(3-)) band spectral fitting model. Each of the methods resulted in a different determination for the carbonate content when using the same measurement data. The method that used the full-width-at-half-maximum of the ν(1)(PO(4)(3-)) band to determine the B-type carbonate concentration was found to be in best agreement with (i) the results (using the acid digestion method) of teeth collected from the same sample population and (ii) previously reported values for both enamel and dentine. The use of a multiple-band spectral fitting model produced the highest determination precision (particularly in the case of dentine).

Acidogenic potential of soy and bovine milk beverages.

Soy beverages are water extracts of whole soybeans and are often promoted as a healthy alternative to bovine milk. Little analysis has been carried out to determine the effects of soy beverages on oral health, especially their potential acidogenicity. OBJECTIVES: The aim of this study was to determine the potential acidogenicity of a range of soy and bovine milk beverages. METHODS: In vitro acid production by Streptococcus mutans was measured in soy and milk beverages at a constant pH of 6.5 or 5.5, as was the fall in pH over a 10 min period. The acid buffering capacity and calcium and phosphate concentrations (total and soluble) of the beverages were also determined. RESULTS: The rate of acid production by S. mutans in the milk beverages was five to six times lower at pH 6.5 than in the soy beverages and three to five times lower at pH 5.5. Whilst the pH fall in the presence of S. mutans over 10 min was negligible in the milk beverages there was a significant decrease in pH in the soy beverages. This was also reflected in the lower buffering capacity of the soy beverages. The levels of soluble calcium in the soy beverages were lower than those in the milk beverages although total calcium contents were similar. CONCLUSIONS: Soy beverages have a higher potential acidogenicity than bovine milk beverages. CLINICAL SIGNIFICANCE STATEMENT: Patients consider soy beverages to be a healthy, low cariogenic alternative to other beverages, including bovine milk. This study shows that soy beverages have a higher potential acidogenicity than bovine milk and therefore may have a greater potential cariogenicity.

Remineralisation by chewing sugar-free gums in a randomised, controlled in situ trial including dietary intake and gauze to promote plaque formation.

Remineralisation has been shown to be an effective mechanism of preventing the progression of enamel caries. The aim of this double-blind, randomised, cross-over in situ study was to compare enamel remineralisation by chewing sugar-free gum with or without casein phosphopeptide amorphous calcium phosphate (CPP-ACP) where the enamel lesions were exposed to dietary intake and some were covered with gauze to promote plaque formation. Participants wore removable palatal appliances containing 3 recessed enamel half-slabs with subsurface lesions covered with gauze and 3 without gauze. Mineral content was measured by transverse microradiography, and plaque composition was analysed by real-time polymerase chain reaction. For both the gauze-free and gauze-covered lesions, the greatest amount of remineralisation was produced by the CPP-ACP sugar-free gum, followed by the gum without CPP-ACP and then the no-gum control. Recessing the enamel in the appliance allowed plaque accumulation without the need for gauze. There was a trend of less remineralisation and greater variation in mineral content for the gauze-covered lesions. The cell numbers of total bacteria and streptococci were slightly higher in the plaque from the gauze-covered enamel for 2 of the 3 treatment legs; however, there was no significant difference in Streptococcus mutans cell numbers. In conclusion, chewing sugar-free gum containing CPP-ACP promoted greater levels of remineralisation than a sugar-free gum without CPP-ACP or a no-gum control using an in situ remineralisation model including dietary intake irrespective of whether gauze was used to promote plaque formation or not.

An X-ray microtomographic study of natural white-spot enamel lesions.

White-spot enamel lesions are an early presentation of dental caries and are ideally managed by non-invasive procedures. The aim of this study was to characterize white-spot enamel lesions by x-ray microtomography. In particular, mineral content across the lesion from the surface to the base of the lesion was measured and surface layers defined. Molars with long buccal white-spot enamel lesions were collected, photographed, and each sectioned to produce 3 500-µm-thick sections. The sections were mounted and imaged by quantitative x-ray microtomography at a 15-µm voxel size. We analyzed line profiles through the middle of each 3D image to determine mineral content and depth. The surface layer thickness of the lesions ranged from 35 to 130 µm, with the maximum mineral content in this layer being 74% to 100% of that of sound enamel. The average mineral content across the lesions ranged from 1.73 to 2.48 g/cm(3). No significant differences could be found between lesions clinically categorized as active and those categorized as inactive. However, for depth-matched active and inactive lesions, the active lesions exhibited a more porous surface layer than the inactive lesions. White-spot enamel lesions are highly variable, with surface layers of considerable thickness.

Effect of casein phosphopeptide-amorphous calcium phosphate added to acidic beverages on enamel erosion in vitro.

BACKGROUND: To investigate, in vitro, the effect on enamel erosion of the addition of 0.2% w/v casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) to four commercially-available soft drinks, two of which were carbonated. METHODS: Enamel specimens (n=27) were sectioned from sound extracted human third molar teeth and polished to a mirror finish. Exposed enamel windows of 1 mm2 were created by painting the surface with acid-resistant nail varnish. Four citric flavoured soft drinks (pH range 2.2 to 2.4) and distilled deionized water (DDW) were tested. Each drink was tested with and without 0.2% CPP-ACP w/v. The specimens were placed into 50 mL of solution at 37 °C for 30 minutes, rinsed and varnish removed. The samples were profiled with a white light profilometer and erosive depths recorded. RESULTS: All soft drinks tested caused enamel erosion but adding 0.2% w/v CPP-ACP significantly reduced (p<.05) erosive depth in all test solutions in comparison with the solutions without CPP-ACP. The erosive depths for all solutions with 0.2% CPP-ACP did not differ significantly from those of DDW. CONCLUSIONS: Adding CPP-ACP at 0.2% w/v significantly decreased the erosivity of all four soft drinks. The erosivity of the soft drinks with 0.2% CPP-ACP added did not differ significantly from that of distilled water.

New approaches to enhanced remineralization of tooth enamel.

Dental caries is a highly prevalent diet-related disease and is a major public health problem. A goal of modern dentistry is to manage non-cavitated caries lesions non-invasively through remineralization in an attempt to prevent disease progression and improve aesthetics, strength, and function. Remineralization is defined as the process whereby calcium and phosphate ions are supplied from a source external to the tooth to promote ion deposition into crystal voids in demineralized enamel, to produce net mineral gain. Recently, a range of novel calcium-phosphate-based remineralization delivery systems has been developed for clinical application. These delivery systems include crystalline, unstabilized amorphous, or stabilized amorphous formulations of calcium phosphate. These systems are reviewed, and the technology with the most scientific evidence to support its clinical use is the remineralizing system utilizing casein phosphopeptides to stabilize and deliver bioavailable calcium, phosphate, and fluoride ions. The recent clinical evidence for this technology is presented and the mechanism of action discussed. Biomimetic approaches to stabilization of bioavailable calcium, phosphate, and fluoride ions and the localization of these ions to non-cavitated caries lesions for controlled remineralization show promise for the non-invasive management of dental caries.

Erosive potential of beverages sold in Australian schools.

BACKGROUND: Dental erosion is an increasingly prevalent problem in Australia. The aim of this study was to analyse the composition and erosive potential of beverages sold for consumption in Victorian schools. METHODS: Fifteen drinks were selected and analysed to determine their pH, titratable acidity and ionic composition (calcium, fluoride and inorganic phosphate). The erosive potential of the beverages was measured by analysing weight loss, surface loss and the release of calcium ions from human enamel following a 30-minute or 24-hour exposure. The association of the chemical parameters with the measures of erosion was determined using Spearman's rank correlation. RESULTS: All beverages tested except the milks and the bottled water produced significant dental erosion in vitro. The only chemical parameter that correlated significantly with all measures of erosion was the initial pH of the beverage (p < 0.01). Levels of fluoride similar to those of Australian reticulated water were found in the carbonated beverages. CONCLUSIONS: The majority of the tested beverages sold from school canteens exhibited erosive potential.

Consumption of milk with added casein phosphopeptide-amorphous calcium phosphate remineralizes enamel subsurface lesions in situ.

BACKGROUND: Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) is an anticariogenic agent that is suitable to be added to foods. The aim of this double-blind, three-way crossover randomized study was to investigate the capacity of CPP-ACP, when added to bovine milk, to remineralize enamel subsurface lesions in situ. METHODS: Ten subjects drank 100 mL of bovine milk containing no added CPP-ACP (control milk), 0.2% (w/v) CPP-ACP or 0.3% (w/v) CPP-ACP, for 30 seconds once daily for 15 days, whilst wearing removable appliances with attached slabs of enamel containing subsurface enamel lesions. After each treatment and a one-week washout period, subjects crossed over to another treatment and this was repeated until they had consumed each of the three milk products. At the completion of each treatment the enamel slabs were removed and remineralization was determined using microradiography. RESULTS: The results demonstrated that all three milk samples remineralized enamel subsurface lesions in situ. However, the two milk samples containing added CPP-ACP each produced significantly greater remineralization than the control milk. CONCLUSIONS: The remineralizing effect of CPP-ACP in milk was dose-dependent with milk containing 0.2% CPP-ACP and 0.3% CPP-ACP producing an increase in mineral content of 81% and 164%, respectively, relative to the control milk.

Fluoride and casein phosphopeptide-amorphous calcium phosphate.

Casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) slows the progression of caries and remineralizes enamel subsurface lesions. The aim of this study was to determine the ability of CPP-ACP to increase the incorporation of fluoride into plaque and to promote enamel remineralization in situ. Randomized, double-blind, cross-over studies involved mouthrinses and dentifrices containing CPP-ACP and fluoride. The mouthrinses were used for 60 sec, three times/day for 5 days, and supragingival plaque was collected and analyzed for F. The dentifrices were rinsed as a water slurry for 60 sec four times/day for 14 days in an in situ model. The addition of 2% CPP-ACP to the 450-ppm-F mouthrinse significantly increased the incorporation of fluoride into plaque. The dentifrice containing 2% CPP-ACP produced a level of remineralization similar to that achieved with a dentifrice containing 2800 ppm F. The dentifrice containing 2% CPP-ACP plus 1100 ppm F was superior to all other formulations.

Enamel subsurface lesion remineralisation with casein phosphopeptide stabilised solutions of calcium, phosphate and fluoride.

Casein phosphopeptide stabilised amorphous calcium phosphate (CPP-ACP) and amorphous calcium fluoride phosphate (CPP-ACFP) solutions have been shown to remineralise enamel subsurface lesions. The aim of this study was to determine the effect of ion composition of CPP-ACP and CPP-ACFP solutions on enamel subsurface lesion remineralisation in vitro. CPP-bound and free calcium, phosphate and fluoride ion concentrations in the solutions were determined after ultrafiltration. The ion activities of the free ion species present were calculated using an iterative computational program. The mineral deposited in the subsurface lesions was analysed using transverse microradiography and electron microprobe. CPP was found to stabilise high concentrations of calcium, phosphate and fluoride ions at all pH values (7.0-4.5). Remineralisation of the subsurface lesions was observed at all pH values tested with a maximum at pH 5.5. The CPP-ACFP solutions produced greater remineralisation than the CPP-ACP solutions at pH 5.5 and below. The mineral formed in the subsurface lesions was consistent with hydroxyapatite and fluorapatite for remineralisation with CPP-ACP and CPP-ACFP, respectively. The activity gradient of the neutral ion pair CaHPO(4)(0) into the lesion was significantly correlated with remineralisation and together with HF(0) were identified as important species for diffusion.

Fluoride content of still bottled water in Australia.

BACKGROUND: Recently there has been a considerable increase in the consumption of bottled water in Australia. Overseas studies have found the fluoride levels in many bottled waters are well below levels considered optimal for preventing dental caries. This raises the concern that if bottled water is regularly consumed an effective means of preventing dental caries is unavailable. The aim of this study was to determine the fluoride concentration in 10 popular brands of still bottled water currently sold in Australia. METHODS: The fluoride content of water samples were determined using an ion analyser and compared to a fluoride standard. RESULTS: The fluoride concentration of all bottled waters was less than 0.08 ppm. Only three of the 10 brands indicated the fluoride content on their labels. Melbourne reticulated water was found to be fluoridated at 1.02 ppm. CONCLUSIONS: All bottled waters tested contained negligible fluoride which justifies the concern that regular consumption of bottled water may reduce the benefits gained from water fluoridation. It is recommended that all bottled water companies should consider stating their fluoride content on their labels. This will inform consumers and dental care providers of the levels of fluoride in bottled water and allow an informed decision regarding consumption of fluoridated versus non-fluoridated drinking water.