Australian Dental Journal

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1 Australian Dental Journal The official journal of the Australian Dental Association Australian Dental Journal 2014; 59: doi: /adj Possible ways of reducing dental erosive potential of acidic beverages T Stefanski,* L Postek-Stefanska *Academic Centre for Dentistry, Bytom, Poland. Department of Pediatric Dentistry, Medical University of Silesia, Zabrze, Poland. ABSTRACT Frequent consumption of acidic beverages is related to excessive tooth wear, namely dental erosion. Preventive measures may involve reduction or elimination of acidic drink consumption. However, the success of this approach is difficult to achieve as it is highly dependent on patient compliance. Therefore, a practical way of minimizing the erosive potential of popular acidic drinks may be their chemical modification. The aim of this article was to review the different methods of modification and their shortcomings. The available literature demonstrates that the erosive potential of most acidic beverages could be reduced. To date, the effectiveness of soluble calcium salts supplementation is the best established. However, modification can reduce the sensorial quality of the drink and shorten its shelf-life. There is also a need to evaluate the lowest effective and safe dose of the additive. Keywords: Acidic drinks, dental erosion, erosive potential, prevention, product modification. Abbreviations and acronyms: Ca:P = calcium:phosphorus molar ratio; CPP-ACP = casein phosphopeptide-amorphous calcium phosphate; DS = degree of saturation; F = fluoride; POs-Ca = phosphoryl oligosaccharides of calcium. (Accepted for publication 31 October 2013.) INTRODUCTION Evidence accumulated from observational and experimental studies indicates excessive consumption of acidic beverages poses a risk to the dentition. The acid-induced chemical dissolution of dental hard tissues without the involvement of bacteria from dental plaque has been defined and widely accepted as dental erosion; 1 however, a more accurate definition would be the term dental corrosion. 2 Among a wide range of acids responsible for erosion, the dietary acids are thought to be the main aetiologic agent since the consumption of juices and soft drinks has increased considerably over the last two decades, and in the United Kingdom is reported to have reached litres per person per year in Erosive lesions might lead to the exposure of the dentine, causing dentine hypersensitivity and even pulp exposure in more severe cases. Currently, efforts are being made to reduce chemical damage to teeth by formulating novel anti-erosive dentifrices. Preventive measures may also include the reduction or elimination of acidic drinks from a diet. However, the success of such prophylactic strategies is difficult to achieve (particularly in children and adolescents), as it largely depends on patient compliance. Therefore, a practical way of reducing the harmful influence of popular acidic drinks on teeth can be modification of their chemical composition. 4 The aim of this article was to review the approaches of such modification and discuss the limitations involved. Erosive potential Erosive potential (erosiveness, erosivity) is a measure of detrimental influence exerted by acidic substances on mineralized dental tissues. It not only depends on the chemical composition and physical properties of a product, but also the natural oral environment (biological factors) and individual consumption habits (behavioural factors). Table 1 summarizes the majority of factors affecting erosive potential. In the present review only the modifying factors from the first group will be discussed as they directly characterize a given product. This information has been collected on the basis of the results of investigations into the erosive potential of different beverages Australian Dental Association

2 Reducing dental erosive potential of acidic beverages Table 1. Factors influencing erosive potential of beverages Erosive potential Physicochemical properties of beverages Biological factors Behavioural factors ph titratable acidity buffer capacity type of acid (pk a value) undissociated acid concentration chelating properties (mainly with respect to calcium) degree of saturation with respect to hydroxyapatite [Ca 10 (PO 4 ) 6 (OH) 2 ] and fluorapatite [Ca 10 (PO 4 ) 6 F 2 ] - calcium concentration (Ca 2+ ) - phosphates concentration (PO4 3-, HPO4 2-,H2PO4 - ) - fluoride concentration (F - ) Ca:P molar ratio volume adhesiveness viscosity temperature carbonation other ingredients and interactions between them saliva - salivary flow rate - oral clearance time - mineral content (Ca 2+ 3-,PO 4,F - ) - buffering capacity - salivary response rate to acidic stimulus acquired salivary pellicle - composition (mucins, acidic proline-rich proteins, bicarbonate, Ca 2+, transglutaminase, carbonic anhydrase VI) - thickness - maturity - structure presence of dental plaque oral saliva-to-acidic solution volume ratio structure and susceptibility of tooth surface type of dental tissue (enamel, dentine, root cementum; primary or permanent tooth) tooth tissue composition (form of apatite crystals, CaF 2 layer) position of the tooth in the dental arch relationship of the tooth to the surrounding soft tissues (friction from the tongue) drinking habits - contact time of an acidic substance with tooth - swallowing rate - frequency and duration of acid exposure - liquid flow velocity - use of a straw - abnormal drinking habits (e.g. sipping, swishing, holding an acid beverage in the vestibule) time of day of exposure (morning, evening, bedtime) oral hygiene practises - frequencey - type of dentifrice - type active ingredient - time elapsed between consumption and toothbrushing - time elapsed between toothbrushing to consumption mouthrinsing with acid neutralizer (water, NaHCO3) after erosive challenge tooth bleaching 2014 Australian Dental Association 281

3 T Stefanski and L Postek-Stefanska Degree of saturation Among chemical parameters, the degree of saturation (DS) of the drink with respect to dental minerals (hydroxyapatite, fluoroapatite) is known to be strongly correlated with erosion rate. 5 DS is determined by calcium, phosphate, fluoride concentration and ph of the solution. The concentration gradient of those ions is thought to be the basic thermodynamic driving force for dissolution. However, two acidic solutions with similar DS may have completely different erosive potentials. 6 This implies other variables exist (Table 1), such as Ca:P molar ratio, type of acid, calcium chelating properties, undissociated acid concentration, 7 adhesiveness. These variables should also be taken into consideration when formulating beverages with a reduced erosive potential. Methods for measuring dental erosive potential It is said erosive lesion occurs in three stages: (1) early demineralization and softening of the tooth tissue without surface loss (nanoscopic changes); (2) microscopic material loss; and (3) a clinically visible erosive lesion (macroscopic change). 8 The erosive potential of modified and unmodified products (as a control group) is most frequently assessed on the basis of enamel erosive lesions in stage 1 and 2. Visual evaluation at stage 3 is very subjective and lacks precision. A basic quantitative method for examining tooth tissue softening (stage 1) is measurement of microhardness or nanohardness before and after exposure to the examined beverage. An additional qualitative evaluation of a lesion can be conducted in an atomic force microscope or a scanning electron microscope. Sometimes it is not the tooth tissue that is examined but the acidic solution in which it was immersed; by measuring the concentration of released Ca 2+ and 3- PO 4 ions per 1 mm 2 of the exposed tissue, or by taking regular measurements of the solution ph, caused by a reaction of H + ions of the solution with hydroxyapatite (ph-stat assessment). Loss of tooth tissue in an erosive lesion (stage 2) is most frequently assessed in relation to a fragment of tooth surface protected against the acidic solution effect (usually by means of adhesive tape or nail varnish). Measurements are taken by a profilometer (optical or contact) or confocal laser scanning microscope. Nearly all the above methods require special preparation of a tooth sample so that its surface is ideally flat (cutting, mounting, grinding, polishing). Currently, there is no fully validated method for measuring erosive lesions directly on the teeth in the oral cavity (in vivo). Most investigations into the erosiveness of beverages have been conducted in vitro. However, due to the influence of many other factors and not only the properties of the product itself, it has to be emphasized that the most reliable research into the effect of food on teeth are in situ investigations, i.e. extraoral assessment of tooth specimens worn in the oral cavity by volunteers on custom-made intraoral appliances, orthodontic brackets or bands. Sometimes erosive potential is determined solely on the basis of chemical parameters of a product; most frequently ph, titratable acidity and buffer capacity. According to many suggestions, 9 11 the best determinant of erosiveness is titratable acidity (expressed by the amount of base needed to raise the initial ph to 7.0). However, some authors indicate both ph and titratable acidity or buffer capacity are reliable prognostics of the erosive process; for the sake of accuracy it should be said ph characterizes erosive potential better when a beverage is consumed in large quantities and its time of contact with dental tissue is short, whereas titratable acidity is a better determinant if a small amount of beverage is mixed with saliva and stays in the oral cavity longer Both ph and titratable acidity, or buffer capacity, provide an approximate indication of the erosive potential of a product as many other factors are also involved (Table 1). Methods for reducing the erosive potential Acid profile change Organic acids are the basic ingredients of many beverages. Dominant acids in fruit drinks are citric acid (C 6 H 8 O 7 ) [E330] and malic acid (C 4 H 6 O 5 ) [E296]. Ready-made juices contain ~0.3% of citric acid, fresh orange and apple juice ~1%, and its concentration in lemon juice may reach up to 6%. The acid profile of juices may depend on the variety of fruit, the climate and place of its origin, the time and conditions of storage before processing as well as on the production process itself, and the time and conditions of storing the ready-made juices. The presence of fumaric and lactic acids is closely related to microbial spoilage. 17 Cola-type soft drinks contain mainly phosphoric acid (H 3 PO 4 ) [E338], sometimes ascorbic acid (C 6 H 8 O 6 ) [E300], lactic acid (C 3 H 6 O 3 ) [E270] or in the case of fizzy drinks, carbonic acid (H 2 CO 3 ) formed by carbon dioxide [E290] in solution. Lactic acid present in food products is a metabolic product of Lactobacillus bacteria in the fermentation process; it is contained in dairy products (yoghurt, cheese, kefir), as well as in pickled vegetables (sauerkraut, cucumbers). In lighttype beverages (e.g. Cola light) both phosphoric and citric acids are used. Some soft drinks (Sprite) contain Australian Dental Association

4 Reducing dental erosive potential of acidic beverages mainly citric acid. In contrast, tartaric acid (C 4 H 6 O 6 ) [E334] dominates in wine and grapes and, in smaller amounts, malic acid, citric acid and succinic acid (C 4 H 6 O 4 ) [E363]. Oxalic acid (C 2 H 2 O 4 ) is contained chiefly in sorrel and rhubarb. The presence of acids in many beverages is responsible for their refreshing taste and storage stability. Therefore, complete elimination of this ingredient is impossible and impractical. Chemical dissolution of tooth tissue may be caused by both H + (H 3 O + ) ions and anions capable of binding or complexing calcium. 18 Two most frequently occurring acids, citric and phosphoric acid, are three-proton acids dissociating in three stages, which means a mixture of hydrogen ions, acid anions and undissociated acid molecules are formed in the solution. From a theoretical point of view, both acids are very erosive because complete dissociation of one molecule results in the formation of three hydrogen atoms. Most in vitro research has shown that citric acid is more erosive than phosphoric acid, although contradictory findings were presented in earlier reports The greater erosive potential of citric acid can be explained by its increased capability of calcium complexation due to the molecule shape and presence of three carboxylic groups. Formation of a strong bond may even draw the calcium out of the hydroxyapatite crystalline structure. However, it should be stressed that complexation (chelation) of calcium ions takes place mainly at a higher ph ( ). 18 The argument weighing in favour of the reduced erosiveness of phosphoric acid is because dissociation of this acid molecule results in the formation of phosphate ions, which can slightly reduce hydroxyapatite dissolution. It has been suggested that citric 28,29 or phosphoric acid 29 in certain beverages should be replaced by malic acid given that exposure to malic acid leads to less enamel damage than exposure to citric and phosphoric acids. 29,30 Acidity reduction Modification of beverages by increasing their ph (>3.8) and lowering of titratable acidity may result in a considerable reduction of erosive potential, 10,31 as these parameters are good determinants of erosiveness. Modified sports drinks with ph ranging from 5.5 to 5.6 have a significantly weaker effect on hydroxyapatite dissolution compared to original beverages, the ph of which reaches 3.0 to However, such modifications are not favourable for technological (shorter shelf-life) and sensory reasons (the drink loses its characteristic pungent, refreshing taste). It should be emphasized that increasing a product s ph, even to the value of 7.0 does not make the drink completely safe for teeth as some acid anions (citrate > lactate > phosphate) maintain the ability to bind calcium. Sugar content Large amounts of sugars (glucose, sucrose, fructose, maltodextrin) are contained in sports drinks. Replacement of the remaining saccharides with only maltodextrin characterized by a low glucose equivalent reduces the acidity and cariogenic potential of a drink. 33 Sucrose alone does not affect the erosiveness of grapefruit juice but it can enhance its cariogenic potential Aspartame [E951], which is contained in many diet drinks (so-called light drinks), can contribute to a slightly lower erosiveness of Coca-Cola Light compared to the traditional drink. 37 In the saliva environment, the hydrolysis of aspartame leads to the formation of phenylalanine, which probably acts as a buffer system. 37 Calcium Most investigations aimed at reducing the erosive potential of acidic products have focused on the addition of calcium. According to the Law of Mass Action, the rate of hydroxyapatite dissolution: Ca 10 (PO 4 ) 6 (OH) 2 + 8H + 10Ca HPO 4 + 2H 2 O could be slowed if the solvent contains the products of this reaction: the calcium and phosphate ions (depending on ph: PO 3-4, HPO 2-4, H 2 PO - 4 ). Indirect evidence supporting this phenomenon is because acidic dairy products (such as yoghurt and kefir) with their naturally high calcium and phosphate content, have very small, sometimes undetectable, erosive potential despite the presence of lactic acid (ph ~4.0). 38 As mentioned earlier, the degree of saturation of the beverage with respect to hydroxyapatite is an important parameter related to the rate of erosion. 5 7 Theoretically, beverage saturated or supersaturated with respect to hydroxyapatite (DS 1.0) is not expected to cause enamel dissolution; however, such modification might result in an unpleasant taste and be dangerous and impossible to apply in the food industry. Nonetheless, it has been demonstrated that considerably lower erosiveness is possible to achieve even when the drink has a low degree of saturation and low ph. Barbour et al. found an approximate threshold condition for citric acid (ph 3.3) defined by a calcium concentration of 120 mm and a phosphate concentration of 0.57 mm. 6 Despite being highly undersaturated (DS ~0.104), the solution showed no significant erosive potential with respect to enamel and using greater concentrations of calcium did not provide any additional benefit. However, when con Australian Dental Association 283

5 T Stefanski and L Postek-Stefanska suming more than 520 ml of such modified citrus beverages there is a risk of exceeding the tolerable upper intake level of calcium (2.5 g per day), resulting in adverse effects (nausea, vomiting, constipation, suppression of intestinal absorption of other mineral nutrients, such as zinc, magnesium and phosphates, and an increased risk of kidney stones). Obviously, the addition of calcium can play an important role in the prevention of this nutrient deficiency in the organism, but considering consumer health safety, it is preferable to establish an optimal anti-erosive and tolerable level of anti-erosive additive. One of the commercially available low-erosive products has a high content of calcium (40 mm = 1.6 g/l). A four times lower concentration of calcium (10 mm = 0.4 g/l) also proved to significantly reduce the erosive potential of orange juice in the in situ and in vitro investigations, 39,40 though to a lesser extent. 40 A low concentration of 1 mm (0.04 g/l) of calcium reduces the erosiveness of 1% citric acid 41 and popular acidic drinks according to some in vitro studies, 42,43 whereas other investigations showed no such effect. 21 Some beverages enriched with calcium (sometimes with vitamin D 3 ) include Calci-Cola (20 mm calcium); Calci-Sport (24.5 mm calcium); Calci-Orange (24 mm calcium) by Calcium Beverage Company (USA); 7-Up plus (11 mm calcium); and Minute Maid Ca orange juice (44 mm calcium, Coca Cola Co.). 14,31,44 Although in vitro research showed a less detrimental effect of these beverages on teeth compared to their unmodified versions, on the labels only their bone reinforcement and osteoporosis preventive effect is highlighted. An exception was Ribena Toothkind blackcurrant juice (23.75 mm of calcium) produced by SmithKline Beecham (currently Glaxo- SmithKline), which was withdrawn from sale following a controversial advertising campaign. 45 A series of in vitro and in situ investigations has demonstrated a significantly lower erosiveness of blackcurrant juices and concentrates modified with different concentrations of calcium compared to non-modified juices. 39,46 49 Also a prototype carbohydrate-electrolyte sports orange drink with 355 ppm of calcium (~8.9 mm) ingested during exercise was less harmful to the teeth. 50 Of the Australian sports drinks, Sukkie and Endura have been shown to have a very low erosive potential due to high calcium content: calcium amino acid chelate in Endura (3 mm calcium) and calcium lactate in Sukkie (11 mm calcium), and high ph (~4.9). However, the taste of those drinks is less acceptable than that of more acidic sports beverages. 51 In terms of product modification, the following calcium salts were used: tricalcium phosphate [E341iii]; 52 calcium lactate [E327]; 40,53 55 calcium gluconate [E578]; 14 calcium carbonate [E170]; 55 calcium citrate [E333]; 56 calcium chloride [E509]; 26,41,42 and calcium citrate malate. 57 All except 0.13% calcium chloride proved effective. 26 In earlier studies with laboratory animals, 26,52,53,55 the erosive effect of different drinks was measured macroscopically by visual inspection but this was very subjective and less precise than currently used laboratory assessment methods. When choosing a modifier, one must take its solubility into consideration. The anti-erosive effect of a particular compound depends on the degree of ionization and saturation. In order to effectively investigate the modifiers, it is recommended that the ph of the examined solutions should be adjusted so that the results will not depend on hydrogen ion concentration (most modifiers increase ph). 4 Two per cent tricalcium phosphate added to grapefruit juice almost completely reduced its erosive potential with respect to both enamel and dentine. 52 However, it might have also been responsible for the unacceptable metallic taste. 56 In addition, it is a poorly soluble compound, especially at neutral ph. Due to this limitation, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) was used. It has been shown in vitro that CPP-ACP reduces the erosiveness of acidic drinks equally efficiently. 58,59 A carrier of calcium and phosphate ions can also be phosphoryl oligosaccharides of calcium (POs-Ca), which are produced by enzymatic digestion of potato starch. 60 It has been proved under in vitro conditions that consumers can effectively reduce the erosive effect of orange juice by adding commercially available preparations of calcium in a form of effervescent tablets. Dissolving one such tablet (500 mg of calcium as calcium carbonate) in 200 ml juice gives an effective concentration of calcium. 61 Phosphates The addition of single orthophosphate ions in the form of 0.21% monosodium orthophosphate [E341i] does not lower the erosive potential of acidic drinks as effectively and permanently as monocalcium phosphate. 26 However, in another study 1% NaH 2 PO 4 reduced erosive potential in vitro and in vivo. 35 Frozen juices in the form of ice lolly melts with the addition of phosphate ions and a low content of calcium (Ca:P ratio ~0.7) demonstrated lower erosiveness. 62 On the basis of research conducted by Hay et al., 52 it is impossible to determine whether the significant anti-erosive effect is caused by phosphate ions alone, or by calcium ions, as the authors used compounds of calcium and phosphorus (Ca 3 PO 4 ) or a mixture of calcium salts and compounds with a phosphate group (e.g. CaHPO 4 with calcium acetate) Australian Dental Association

6 Reducing dental erosive potential of acidic beverages In order to reduce the erosive potential, polyphosphates (having a linear structure) and metaphosphates (with a ring structure), referred to as condensed phosphates, were also used with a positive effect. 35,63,64 They consist of P-O-P chains, having the following formula: Na n+2 P n O 3n+1. They are among others used as an additive for meat preserves and soft drinks [E451, E452]. It was observed in earlier in vitro studies that the application of polyphosphates and metaphosphates before hydroxyapatite erosive exposure (therefore, still in the conditions of a higher ph) reduced erosive potential by 20 50%. 65 Later investigations conducted with the ph-stat method revealed that linear sodium polyphosphate (0.2 g/l) considerably reduced the dissolution of hydroxyapatite by ~64% in 0.3% citric acid (ph 3.2), 63 and by ~84% in orange juice (ph 3.8). 54 In the process of enamel dissolution by an acidic drink, phosphate groups of polyphosphate probably bind with hydroxyapatite, reducing the surface area available for dissolution and replacing HPO 2-4 groups, hence inhibiting detachment of subsequent ions. 63,66 Polyphosphates have the ability to adsorb positively charged molecules on the solid surface as a result of electrostatic and covalent effects. Therefore, it is suggested they can form a protective layer, which inhibits the process of demineralization. 66 The anti-erosive effect of polyphosphates is definitely weaker in relation to dentine, as this tissue contains much less inorganic substance in the form of hydroxyapatite than enamel. 54 The effectiveness and persistence of the polyphosphates action is presumably proportional to their chain length, which has been discovered among others on the basis of a weaker antierosive effect of sodium tripolyphosphate and sodium pirophosphate tetrabasic. 54,63 At this point it is important to highlight that all the above mentioned studies were conducted under in vitro conditions, without the presence of saliva. 54,63,65,66 Although polyphosphates in a concentration ranging from 0.01 to 1.0 g/l are believed to reduce the erosive potential of acidic drinks, 67 their effectiveness under in situ conditions proved to be different. 40,64 A long-term (10-day) in situ study revealed the anti-erosive effect of 0.02% sodium hexametaphosphate and the synergic effect with 0.4 mg/l calcium ions and 0.03% xanthan gum, but it is impossible to find which compound causes a greater reduction of erosive potential because no group with an experimental solution containing calcium ions alone was established. 64 In a short in situ study the addition of the same amount of linear sodium polyphosphate resulted in a significantly weaker anti-erosive effect as it only slightly and insignificantly reduced the erosive potential of orange juice. 40 No synergic effect was observed in a combination with calcium ions, although the same researchers reported it under in vitro conditions. 54 This could have been because in oral cavity conditions the adsorption of phosphates is disturbed by some saliva ingredients, which also have affinity for hydroxyapatite surface. 63 An earlier in vivo study also did not find any reduced enamel erosion in the teeth of rats fed with a grape juice containing 0.15% sodium hexametaphosphate and 0.15% sodium trimetaphosphate. 26 Fluoride Many older studies with rats fed with experimental solutions revealed that fluoride in the form of sodium fluoride reduced the erosive potential of an acidic solution in the following concentrations: 50 ppm in grapefruit juice; ppm in an experimental sports drink; 68,69 5 ppm in a solution of citric acid 70 and Coca-Cola; 71 2 ppm in fruit juices; 20 and 1.9 ppm in grapefruit juice. 72 Also, 40 ppm of fluoride as sodium monofluorophosphate reduces the erosive potential, but not to such a large extent as monocalcium phosphate. 26 More recent in vitro studies have shown a fizzy drink modified with calcium fluoride lessened erosion only when ph > In contrast, enriching a 0.3% solution of citric acid and fruit juices with 1 ppm of fluoride reduced erosiveness even at lower ph. 74 However, the benefits resulting from such supplementation are not substantial, especially in the context of the high effectiveness of calcium compounds. Moreover, fluoride is not an approved food additive in the European Union and cannot be used to reduce the erosive potential of acidic drinks for toxicological reasons. Naturally occurring low concentrations of fluoride in commercially available beverages (<1 ppm) do not influence the erosion process. 31 Iron Iron, in the form of ferrous sulphate, can reduce the erosive potential of Coca-Cola only in high concentrations: 10 mm, mm and 60 mm. 76,77 At low concentrations (1 mm), even with an addition of fluoride (0.047 mm), adding this element is ineffective. 21,43,77 The optimal erosion-protective concentration of iron was found to be 15 mm. 76 It is hypothesized that the anti-erosive action of iron is due to precipitation of ferric phosphate 77 or hydrous iron oxides 76 as a thin acid-resistant coating on the enamel surface. However, apart from toxicological aspects, a high concentration of iron causes an unpleasant metallic taste and leads to teeth discolouration. Peptides Among peptides, the most promising anti-erosive effect seem to have compounds contained in milk and 2014 Australian Dental Association 285

7 T Stefanski and L Postek-Stefanska dairy products, which have a well-documented hindering influence on the dental tissue demineralization process, mainly due to a high content of calcium and phosphorus, although this might not be the only reason. 78 The majority of research is focused on caseins (mainly the already mentioned casein phosphopeptides), which in a concentration of 0.002% to 0.2% adsorb on the salivary pellicle or directly on the enamel surface and reduce its dissolution in vitro, probably by forming an ion-diffusion retarding layer. 78,79 Recently, the anti-erosive and remineralizing properties of proteose-peptone and glycomacropeptide, 80,81 as well as hen egg ovalbumin 79 have been reported. However, the addition of 0.2% ovalbumin reduces the erosive potential of citric acid in vitro to a lesser extent than 0.2% casein. 79 Polysaccharide hydrocolloids (polymers) In the food industry, hydrocolloids are applied mainly as stabilizers and thickeners used for texture modification. It has been speculated that when added in small concentrations (0.02% to 1%) to an acidic solution, they can form a protective thin polymer layer, reducing the enamel erosion process. 63,82,83 Additionally, solutions of these compounds are characterized by a higher viscosity, which may also affect the erosive potential (more stable Nernst diffusion layer, dissolution reaction hindering). 84 To date, most research has been conducted with 0.02% xanthan gum [E415], which under both in vitro 63 and in situ 85 conditions reduced the erosive potential of acidic solutions. However, the results of other in vitro investigations contradict this finding. 54 The reduced erosive potential was also observed after adding 0.02% carboxymethylcellulose [E466], 63 1% propylene glycol alginate [E405], 82 1% gum arabic [E414] 82 and 1% highly esterified pectin [E440]. 82 The results of the quoted studies are contradictory with regards to both the effectiveness of the examined compounds, e.g. gum arabic, 63,82 and the formation of a polymer membrane. 83,84 It must be emphasized that in situ investigations in which saliva proteins can compete with hydrocolloid molecules for a place on the enamel surface in the formation of a protective membrane have not yet been conducted. It should also be noted that although the newly formed membrane structure can hinder the erosion process, it can also reduce tooth tissue remineralization. In future, the possible positive and negative interactions of the added compounds should be investigated. For example, a positive effect in strawberry juices is slowing the degradation of anthocyanins by 0.1% high methyl pectin, whilst a negative effect is the precipitation of solid particles. CONCLUSIONS The erosive potential of most acidic beverages can be considerably reduced by modifying their composition. Currently, the best documented is the effectiveness of calcium supplementation. Calcium containing beverage formulations may be considered as one of the possible approaches to limit dental erosion, and may be advised for high risk individuals who cannot reduce their dietary acidic intake. It must be noted that product modification may involve a lower sensorial quality, reduced availability of some natural nutrients, storage time shortening or precipitation of the modifier. Bearing in mind consumer health safety, it is necessary to establish maximum amounts of substances added to drinks on the basis of tolerable upper levels, taking into consideration a scientific evaluation of risk, the various degrees of sensitivity of particular consumer groups as well as consumption of these nutrients with food and from other sources, e.g. with water. REFERENCES 1. Imfeld T. Dental erosion. Definition, classification and links. Eur J Oral Sci 1996;104: Grippo JO, Simring M, Schreiner S. Attrition, abrasion, corrosion and abfraction revisited. J Am Dent Assoc 2004;135: British Soft Drinks Association. The 2012 UK Soft Drinks Report: Grenby TH. Lessening dental erosive potential by product modification. Eur J Oral Sci 1996;104: Barbour ME, Parker DM, Allen GC, Jandt KD. Human enamel erosion in constant composition citric acid solutions as a function of degree of saturation with respect to hydroxyapatite. J Oral Rehabil 2005;32: Barbour ME, Parker DM, Allen GC, Jandt KD. Enamel dissolution in citric acid as a function of calcium and phosphate concentrations and degree of saturation with respect to hydroxyapatite. Eur J Oral Sci 2003;111: Shellis RP, Barbour ME, Jesani A, Lussi A. Effects of buffering properties and undissociated acid concentration on dissolution of dental enamel in relation to ph and acid type. Caries Res 2013;47: Jandt KD. Probing the future in functional soft drinks on the nanometre scale towards tooth friendly soft drinks. Trends Food Sci Tech 2006;17: Edwards M, Creanor SL, Foye RH, Gilmour WH. Buffering capacities of soft drinks: the potential influence on dental erosion. J Oral Rehabil 1999;26: Grenby TH, Philips A, Desai T, Mistry M. Laboratory studies of the dental properties of soft drinks. Br J Nutr 1989;62: Grenby TH, Mistry M, Desai T. Potential dental effects of infants fruit drinks studied in vitro. Br J Nutr 1990;64: Malara P, Kloc-Ptaszna A, Dobrzanski LA, Gorniak M, Stefanski T. Effect of water dilution and alcohol mixing on erosive potential of orange juice on bovine enamel. Arch Mater Sci Engin 2013;62: Australian Dental Association

8 Reducing dental erosive potential of acidic beverages 13. Hannig C, Hamkens A, Becker K, Attin R, Attin T. Erosive effects of different acids on bovine enamel: release of calcium and phosphate in vitro. Arch Oral Biol 2005;50: Hara AT, Zero DT. Analysis of the erosive potential of calcium-containing acidic beverages. Eur J Oral Sci 2008; 116: Jensdottir T, Holbrook P, Nauntofte B, Buchwald C, Bardow A. Immediate erosive potential of cola drinks and orange juices. J Dent Res 2006;85: Rugg-Gunn AJ, Maguire A, Gordon PH, McCabe JF, Stephenson G. Comparison of erosion of dental enamel by four drinks using an intra-oral appliance. Caries Res 1998; 32: G okmen V, Acar J. Fumaric acid in apple juice: a potential indicator of microbial spoilage of apples used as raw material. Food Addit Contam 2004;21: Featherstone JD, Lussi A. Understanding the chemistry of dental erosion. Monogr Oral Sci 2006;20: Beyer M, Reichert J, Bossert J, Sigusch BW, Watts DC, Jandt KD. Acids with an equivalent taste lead to different erosion of human dental enamel. Dent Mater 2011;27: Holloway PJ, Mellanby M, Stewart RJC. Fruit drinks and tooth erosion. Br Dent J 1958;104: Magalh~aes AC, Moraes SM, Rios D, Wiegand A, Buzalaf MA. The erosive potential of 1% citric acid supplemented by different minerals: an in vitro study. Oral Health Prev Dent 2010;8: Meurman JH, Frank RM. Progression and surface ultrastructure of in vitro caused erosive lesions in human and bovine enamel. Caries Res 1991;25: West NX, Hughes JA, Addy M. The effect of ph on the erosion of dentine and enamel by dietary acids in vitro. J Oral Rehabil 2001;28: Wiegand A, Bliggenstorfer S, Magalh~aes AC, Sener B, Attin T. Impact of the in situ formed salivary pellicle on enamel and dentine erosion induced by different acids. Acta Odont Scand 2008;66: McCay CM, Will LJ. Erosion of molar teeth by acid beverages. J Nutr 1949;39: Reussner GH, Coccodrilli G Jr, Thiessen R Jr. Effects of phosphates in acid-containing beverages on tooth erosion. J Dent Res 1975;54: Stephan RM. Effects of different types of human foods on dental health in experimental animals. J Dent Res 1966;45: Hughes JA, West NX, Addy M. The protective effect of fluoride treatments against enamel erosion in vitro. J Oral Rehabil 2004;31: Meurman JH, H ark onen M, N averi H, et al. Experimental sports drinks with minimal dental erosion effect. Scand J Dent Res 1990;98: Bibby BG, Mundorff SA. Enamel demineralization by snack foods. J Dent Res 1975;54: Larsen MJ, Nyvad B. Enamel erosion by some soft drinks and orange juices relative to their ph, buffering effect and contents of calcium phosphate. Caries Res 1999;33: Meurman JH, H ark onen M, N averi H, et al. Experimental sports drinks with minimal dental erosion effect. Scand J Dent Res 1990;98: Parker DM, Roedig-Penman A. Alpha-(1,4) linked glucose polymers containing oral compositions to alleviate or prevent tooth damage WO Patent Application No A Hooper S, West NX, Sharif N, et al. A comparison of enamel erosion by a new sports drink compared to two proprietary products: a controlled, crossover study in situ. J Dent 2004;32: McDonald JL, Stookey GK. Laboratory studies concerning the effect of acid-containing beverages on enamel dissolution and experimental dental caries. J Dent Res 1973;52: Spencer AJ, Ellis LM. The effect of fluoride and grapefruit on the etching of teeth. J Nutr 1950;43: Rios D, Honorio HM, Magalh~aes AC, Wiegand A, Machado MAAM, Buzalaf MAR. Light cola drink is less erosive that the regular one: An in situ/ex vivo study. J Dent 2009;37: Lussi A, Jaeggi T, Zero D. The role of diet in the aetiology of dental erosion. Caries Res 2004;38(Suppl 1): Hughes JA, West NX, Parker DM, Newcombe RG, Addy M. Development and evaluation of a low erosive blackcurrant juice drink in vitro and in situ. 1. Comparison with orange juice. J Dent 1999;27: Scaramucci T, Sobral MAP, Eckert GJ, Zero DT, Hara AT. In situ evaluation of the erosive potential of orange juice modified by food additives. Caries Res 2012;46: Attin T, Meyer K, Hellwig E, Buchalla W, Lennon AM. Effect of mineral supplements to citric acid on enamel erosion. Arch Oral Biol 2003;48: Attin T, Weiss K, Becker K, Buchalla W, Wiegand A. Impact of modified acidic soft drinks on enamel erosion. Oral Dis 2005;11: Magalh~aes AC, Moraes SM, Rios D, Buzalaf MA. Effect of iron supplementation of a commercial soft drink on tooth enamel erosion. Food Addit Contam Part A Chem Anal Control Expo Risk Assess 2009;26: Davis RE, Marshall TA, Qian F, Warren JJ, Wefel JS. In vitro protection against dental erosion afforded by commercially available, calcium-fortified 100 percent juices. J Am Dent Assoc 2007;138: BBC News. Court rules against Ribena, URL: Accessed June Hughes JA, West NX, Parker DM, Newcombe RG, Addy M. Development and evaluation of a low erosive blackcurrant juice drink 2. Comparison with a conventional blackcurrant juice drink and orange juice. J Dent 1999;27: Hughes JA, West NX, Parker DM, Newcombe RG, Addy M. Development and evaluation of a low erosive blackcurrant juice drink 3. Final drink and concentrate, formulae comparisons in situ and overview of the concept. J Dent 1999;27: Hughes JA, Jandt KD, Baker N, et al. Further modification to soft drinks to minimise erosion. Caries Res 2002;36: Hunter ML, Hughes JA, Parker DM, West NX, Newcombe RG, Addy M. Development of low erosive carbonated fruit drinks. 1. Evaluation of two experimental orange drinks in vitro and in situ. J Dent 2003;31: Venables MC, Shaw L, Jeukendrup AE, et al. Erosive effect of a new sports drink on dental enamel during exercise. Med Sci Sports Exerc 2005;37: Cochrane NJ, Yuan Y, Walker GD, et al. Erosive potential of sports beverages. Aust Dent J 2012;57: Hay DI, Pinsent BRW, Schram CJ, Wagg BJ. The protective effect of calcium and phosphate ions against acid erosion of dental enamel and dentine. Br Dent J 1962;112: Beiraghi S, Atkins S, Rosen S, Wilson S, Odom J, Beck M. Effect of calcium lactate in erosion and S. mutans in rats when added to Coca-Cola. Pediatr Dent 1989;11: Scaramucci T, Hara AT, Zero DT, Ferreira SS, Aoki IV, Sobral MAP. In vitro evaluation of the erosive potential of orange juice modified by food additives in enamel and dentine. J Dent 2011;39: Wagg BJ, Friend JV, Smith JS. Inhibition of the erosive properties of water ices by the addition of calcium and phosphate. Br Dent J 1965;119: Australian Dental Association 287

9 T Stefanski and L Postek-Stefanska 56. Jensdottir T, Bardow A, Holbrook P. Properties and modification of soft drinks in relation to their erosive potential in vitro. J Dent 2005;33: Andon MB, Kanerva RL, Rotruck JT, Smith KT. Method of preventing tooth enamel erosion utilizing an acidic beverage containing calcium, 1992 US Patent no A. 58. Manton DJ, Cai F, Yuan Y, et al. Effect of casein phosphopeptide-amorphous calcium phosphate added to acidic beverages on enamel erosion in vitro. Aust Dent J 2010;55: Ramalingam L, Messer LB, Reynolds EC. Adding casein phosphopeptide-amorphous calcium phosphate to sports drinks to eliminate in vitro erosion. Pediatr Dent 2005;27: Mita H, Kitasako Y, Takagaki T, Sadr A, Tagami J. Development and evaluation of a low-erosive apple juice drink with phosphoryl-oligosaccharides of calcium. Dent Mater J 2013; 32: Wegehaupt FJ, G unthart N, Sener B, Attin T. Prevention of erosive/abrasive enamel wear due to orange juice modified with dietary supplements. Oral Dis 2011;17: Grenby TH, Saldahna MG. The use of high-phosphorus supplements to inhibit dental erosion demineralisation by ice lollies. Int J Food Sci Nutr 1995;46: Barbour ME, Shellis RP, Parker DM, Allen GC, Addy M. An investigation of some food-approved polymers as agents to inhibit hydroxyapatite dissolution. Eur J Oral Sci 2005;113: Hooper S, Hughes J, Parker D, et al. A clinical study in situ to assess the effect of a food approved polymer on the erosion potential of drinks. J Dent 2007;35: McGaughey C, Stowell EC. Effects of polyphosphates on the solubility and mineralization of HA. Relevance to a rationale for anticaries activity. J Dent Res 1977;56: Schaad P, Thomann JM, Voegel JC, Gramain P. Inhibition of dissolution of hydroxyapatite powder by adsorbed anionic polymers. Colloid Surf A Physicochem Eng Asp 1994;83: Baker NJ, Parker DM. Use of polyphosphate as a tooth erosion inhibitor in acidic compositions. 2007, US Patent Application No Sorvari R, Kiviranta I, Luoma H. Erosive effect of a sport drink mixture with and without addition of fluoride and magnesium on the molar teeth of rats. Scand J Dent Res 1988;96: Sorvari R. Effects of various sport drink modifications on dental caries and erosion in rats with controlled eating and drinking pattern. Proc Finn Dent Soc 1989;85: Zipkin I, McClure FJ. Inhibitory effect of fluoride on tooth decalcification by citrate and lactate in vivo. J Dent Res 1949;28: Shabat E, Anaise J, Westreich V, Gedalia I. Erosion and fluoride content in molar surfaces of rats that drank a cola beverage with and without fluoride. J Dent Res 1975;54: Gedalia I, Anaise J, Westreich V, Fuks A. Predisposition to caries in hamsters following the erosive effect of a commercial citrus beverage administered with and without supplemental fluoride. J Dent Res 1975;54: Larsen MJ, Richards A. Fluoride is unable to reduce dental erosion from soft drinks. Caries Res 2002;36: Hughes JA, West NX, Addy M. The protective effect of fluoride treatments against enamel erosion in vitro. J Oral Rehabil 2004;31: Kato MT, Sales-Peres SHC, Buzalaf MAR. Effect of iron on acid demineralisation of bovine enamel blocks by a soft drink. Arch Oral Biol 2007;52: Buzalaf MAR, Italiani FM, Kato MT, Martinhon CCR, Magalh~aes AC. Effect of iron on inhibition of acid demineralisation of bovine dental enamel in vitro. Arch Oral Biol 2006;51: Kato MT, Maria AG, Sales-Peres SHC, Buzalaf MAR. Effect of iron on the dissolution of bovine enamel powder in vitro by carbonated beverages. Arch Oral Biol 2007;52: Barbour ME, Shellis RP, Parker DM, Allen GC, Addy M. Inhibition of hydroxyapatite dissolution by whole casein: the effects of ph, protein concentration, calcium, and ionic strength. Eur J Oral Sci 2008;116: Hemingway CA, White AJ, Shellis RP, Addy M, Parker DM, Barbour ME. Enamel erosion in dietary acids: inhibition by food proteins in vitro. Caries Res 2010;44: White AJ, Gracia LH, Barbour ME. Inhibition of dental erosion by casein and casein-derived proteins. Caries Res 2011;45: Nejad AS, Kanekanian A, Tatham A. The inhibitory effect of glycomacropeptide on dental erosion. Dairy Sci Technol 2009;89: Beyer M, Reichert J, Heurich E, Jandt KD, Sigusch BW. Pectin, alginate and gum arabic polymers reduce citric acid erosion effects on human enamel. Dent Mater 2010;26: Beyer M, Reichert J, Sigusch BW, Watts DC, Jandt KD. Morphology and structure of polymer layers protecting dental enamel against erosion. Dent Mater 2012;28: Aykut-Yetkiner A, Wiegand A, Bollhalder A, Becker K, Attin T. Effect of acidic solution viscosity on enamel erosion. J Dent Res 2013;92: West NX, Hughes JA, Parker D, et al. Modification of soft drinks with xanthan gum to minimise erosion: a study in situ. Br Dent J 2004;196: Address for correspondence: Associate Professor L Postek-Stefanska Department of Pediatric Dentistry Medical University of Silesia 2 Traugutta Square Zabrze Poland swrzab@sum.edu.pl Australian Dental Association