CHARACTERIZING DENTAL EROSION POTENTIAL OF BEVERAGES AND BOTTLED DRINKING WATER IN BANGLADESH

Proceedings of the International Conference on Chemical Engineering 2014 ICChE2014, 29-30 December, Dhaka, Bangladesh CHARACTERIZING DENTAL EROSION POTENTIAL OF BEVERAGES AND BOTTLED DRINKING WATER IN BANGLADESH Fatima Enam 1, Mehnaz Mursalat 1, Upoma Guha 2, Nirupam Aich 3, Muzahidul Islam Anik 1, Mohidus Samad Khan 1* 1 Department of Chemical Engineering, Bangladesh University of Engineering and Technology (BUET), Dhaka-1000, Bangladesh. 2 Department of Operative Dentistry, University of North Carolina, Chapel Hill, NC 27599. USA 3 Department of Civil, Architectural, and Environmental Engineering, University of Texas, Austin, TX 78712. USA. Dental erosion, caused by prolonged direct contact between tooth surfaces and acidic substances, is a predominant condition that occurs worldwide. Dental erosion is the dissolution of minerals from the tooth surface as a result of exposure to nonbacterial acids. Hydrogen ions (H + ) from acidic solutions can replace the calcium ions (Ca 2+ ) of the enamel, consequently breaking the crystal structure of the enamel and initiating dental erosion. Erosive tooth wear can lead to severe impairment of esthetics along with loss of hardness and functionality. Acidic challenges responsible for dissolution of dental enamel and root dentin can be intrinsic (i.e. gastroesophaegal reflux disease) and extrinsic (i.e. exposure from acidic foods and beverages). Beverages such as soft drinks, energy drinks and fruit juices, and also bottled drinking water have often been linked to dental erosion. ph, titratable acidity, ionic strength, and mineral contents (calcium and phosphate concentration), are considered as the critical parameters for estimating the dental erosion potential of beverages and drinking water. Especially, continuous intake of drinks or food with ph lower than the critical erosive ph of enamel (5.2~5.5) and root dentin (~6.7) are considered to be majorly responsible for dental erosion, however, other parameters will contribute too. In Bangladesh, there is limited scientific information available to assess the potential of dental erosion of the commercially available beverages and drinking water. This article aims to characterize the dental erosion potential of beverages and bottled drinking water available in Bangladesh market. The experimental results indicate that all soft drinks, energy drinks, and juices have high erosive potential, while bottled water samples are potentially nonerosive. These results will be helpful in determining oral health hazard associated with habits of dietary drinks among population of Bangladesh. This study results will be useful for the health professionals, regulatory authorities, and government policy makers for quality control of the available beverages and bottled drinking water available in the local market. Finally, creating awareness among mass population regarding such health hazard potential of common dietary drinks can help remediate a recurring public health issue. 1. INTRODUCTION Dental erosion, acidic dissolution of enamel and dentin major components of dental hard tissue, has progressively become a major concern for detrimental dental health (Lussi 2006, Lussi, Schaffner et al. 2007). Erosion refers to the dissolution of tooth structure under continuous exposure to low ph, while not being associated with bacterial infection (Imfeld 1996). Replacement of minerals, primarily calcium from enamel or hydroxyapatite Ca 5 (PO4) 3 (OH) (s), can induce degradation of teeth structure and upon long-term exposure can lead to severe deleterious impacts on dental aesthetics and functionality such as loss of strength (Lussi 2006). Etiological studies report two major classifications of the causes of the dental erosion intrinsically by the gastroesophaegal reflux disease and extrinsically due to the exposure towards the acidic food and beverages (Zero 1996, Jensdottir, Arnadottir et al. 2004, DDS 2011). Soft drinks, beverages, and juices commonly consumed by the people of Bangladesh have low ph, and might be related to dental erosion issues. Dental erosion potential from regular diet can be appreciated from the ph and titratable acidity (TA) * Corresponding Author: Mohidus Samad Khan, E-mail: mohid@buet.ac.bd

values of the commonly available drinks and food (Brown, Smith et al. 2007, Kitchens and Owens 2007, Cochrane, Yuan et al. 2012). ph values when reach threshold values below 6.7 and 5.2-5.5 can potentially cause erosive wear to root-dentin and enamel, respectively (Dawes 2003, Featherstone and Lussi 2006). Fruits, juices, soft drinks, sports and energy drinks, and some cases bottled water can have ph lower or closer to such values and their continuous consumption can lead to such erosive potential (Larsen and Nyvad 1999, Brown, Smith et al. 2007, Kitchens and Owens 2007, Cochrane, Yuan et al. 2012, Pinto, Bandeca et al. 2013). While ph=-log[h + ] provides the amount of H + ions that will be available to cause replacement of minerals (e.g. calcium) from tooth structure, titratable acidity (TA) provides the amount of alkali required to neutralize the acid or in other words measures the erosive capacity of the food or beverage. The concentrations of calcium (Ca 2+ ) and phosphate (PO 4 3- ) ions and total dissolved solids (TDS) in the exposure media (ingested drinks or food and saliva) provide with the solubility product (K sp ) which eventually dictates the degree of dissolution of enamel (Cochrane, Yuan et al. 2012). Besides, other factors such as frequency of consumption, buffering capacity of saliva, temperature of the drinks, oral hygiene etc., also have shown to impact the absolute erosion caused by the drinks (Amaechi, Higham et al. 1999, Amaechi and Higham 2005). Compromise of dental health through erosion has been increasingly prevalent among both young and adult population worldwide as evidenced from epidemiological studies (Tsinidou 2000, Lussi, Schaffner et al. 2007, Johansson, Omar et al. 2011). A recent study conducted with 147 pregnant women in Dhaka city has shown the prevalence of dental erosion among 52% of the studied population (Mahmud, Begum et al. 2014). This indicates towards high risk for such erosive complications for the entire population. We believe this erosion prevalence will be more due to increased consumption of low ph drinks (as predicted from market research data), poor oral hygiene practice, lack of dental education and affordable dental care among general population of Bangladesh (Sarwar, Kabir et al. 2012, Trefis 2012, Khan, Zaman et al. 2013, Silvi, Islam et al. 2014). Therefore, it becomes essential that systematic evaluation of the erosive potential of commonly consumed food and beverages in Bangladesh has become imperative. However, lack of such studies presents with a critical knowledge gap. The objective of this study is to experimentally analyze different dental erosion indicating parameters, such as ph, TA, TDS, PO 4 3, Ca 2+, of the soft drinks, energy drinks, fruit juices, and bottled drinking water available in the local market of Bangladesh, and evaluate the potential erosive hazard associated with these drinks. 2. MATERIALS AND METHODS 2.1 Sample collection Locally available and/or produced beverages and bottled drinking water samples were collected from different markets and super shops of Dhaka, Bangladesh. The collected samples were broadly classified into four categories: a) soft drinks (14 brands), b) energy drinks (4 brands), c) fruit juices (12 brands; all were mango juices), and d) bottled drinking water (8 brands). For each brand, three (3) samples of different production batches were collected. 2.2 Chemical analyses All the chemicals used were reagent grade. Each test was repeated three times (i.e., samples from three batches and three tests for each sample) and the average results were used for further analysis. All the tests were carried out at room temperature. The ph of each sample drink was measured immediately upon opening. A calibrated bench top ph meter (Hanna HI2211) was used to measure ph of the samples. A HACH Model 44600 Conductivity/TDS Meter was used to measure the TDS of the samples. The TDS of each sample drink was measured immediately upon opening. For carbonated samples, however, the samples were allowed to sit till some of the gas escaped. The titratable acidity (TA) of each sample was measured by titrating 25 ml of each sample with 0.1M NaOH, using phenolphthalein as the indicator. For the samples with an intense color (e.g. black cola), the samples were diluted for accuracy in determining the endpoint. The calcium (Ca 2+ ) concentrations in the samples were determined using complexometric titration method. Ethylenediaminetetraacetic acid (EDTA) solution was prepared by dissolving 1.4612 g of reagent grade EDTA (Sigma Aldrich) in 500ml of water to prepare a 0.01M solution. A ph 11 buffer solution was prepared to maintain an alkaline environment which would help any magnesium precipitate; else the EDTA would simultaneously complex with the magnesium ions. 25ml of the samples were titrated with the EDTA solution, using Calcon as the indicator. The phosphate content of the beverage samples were measured using spectrophotometer (Hach UV/vis spectro-photometer, DR4000). 10 ml samples of the beverages were taken into cuvettes, diluted appropriated so as to reduce color effect or reduce the phosphate (PO 4 3- ) concentration 116

below the maximum threshold of the equipment. Using the preset program for determining total phosphate as orthophosphate, the procedure was carried out. 3. RESULTS AND DISCUSSION The mean values of the experimental results of TDS, ph, TA, phosphate and calcium contents of soft drinks, energy drinks, fruit juices and bottled water are shown in Table 1. The ph, TDS, TA, phosphate and calcium contents of different beverages and bottled drinking water are graphically represented and compared in Fig. 1a-e respectively. 3.1 Soft Drinks Prolonged exposure of teeth to food or drinks with ph values below critical dental erosive ph values can lead to potential dental hard tissue removal by demineralization (Dawes 2003, Fraunhofer and Rogers 2004, Featherstone and Lussi 2006). The soft drink samples had the lowest ph values, with the black cola drinks having the minimum, all below ph 3 (Table 1, Fig. 1a). Low ph and presence of orthophosphoric acids can dissolve protective protein layers deposited on teeth by salivary fluid. Then the drinks can diffuse inside the enamel and can cause leaching of minerals. The black cola drinks had the highest levels of phosphate (PO 3 4 ) - compared to other samples (Fig. 1d). Amongst the black colas Mojo exhibited high 3- PO 4 content, while both Mojo and CocaCola contain relatively high calcium (Ca 2+ ) content compared to other soft drinks (Fig. 1d, e). Virgin Red had the highest TDS while Sprite had the lowest (Fig. 1c). The results for erosive potential for soft drinks are consistent with prior reports for other countries (Fraunhofer and Rogers 2004, Jensdottir, Arnadottir et al. 2004). 3.2 Energy Drinks The energy drinks category had slightly higher ph than the soft drinks (Fig. 1a) but TA values were much higher compared to the soft drinks (Fig. 1c). Studies carried out on sport and energy drinks show that they have a high erosion potential relative to other drinks, which is consistent with studies from other countries (Kitchens and Owens 2007, Pinto, Bandeca et al. 2013). The phosphate levels in energy drinks were found to be lower than that of the soft drinks, especially, black cola drinks (Fig. 1d). Amongst the samples, calcium, TDS and TA were found higher in Red bull compared to other energy drinks (Fig. 1e). The other energy drink Tiger was found to be rich in phosphate as compared to other samples. 3.3 Fruit Juices Fruit juices have a considerable higher ph (>3) but with similar titratable acidity as soft drinks (Fig. 1a, c). This indicates the high erosive potential of the juices which is consistent with literature findings (Larsen and Nyvad 1999). This was true for all the mango juices available in the local market. The concentrations of phosphate were low but calcium content was found higher as compared to other beverages (Table 1). Ceres Mango was found to be more acidic with higher TA (Fig. 1a-b) while Sundrop exhibited the highest calcium and phosphate content among all the juice samples (Table 1). 3.4 Bottled Water The experimental results show that locally available bottled drinking waters possess much lower erosive potential compared to the soft drinks, fruit juices, and energy drinks available in the local market. All the bottled water samples had a ph over 6.7, most of them having a ph over 7, and with almost negligible TA (Table 1; Fig. 1a, c). With the exception of spring water (Evian), other samples had negligible amounts of calcium and phosphate. Among the samples, Spa and Evian showed greater phosphate and calcium content respectively than any other sample (Table 1), while Efad and Aquafina were found to have higher TA (Table 1). All these results indicate towards significantly lower to almost no erosive potential of teeth upon exposure towards bottled drinking water. 3.5 General Comments The experimental results show that all the beverages locally available were acidic, with the soft drinks category having the lowest ph values, followed by the energy drinks, the fruit juices and finally the bottled water samples having a ph close to 7. It is noticeable that most of the samples had a ph below 4.5 which is way below the critical erosive ph values for enamel (5.2-5.5) and dentin (6.5), indicating high erosive potential upon continuous or recurrent consumption with the exception of bottled water samples (Featherstone and Lussi, 2006). TA was the highest for the energy drinks, although the ph values were comparatively less acidic. Calcium was present in high levels in fruit juices compared to other beverages, with extremely low levels in most soft drinks. Phosphate levels, on the other hand, were high in black cola drinks and negligible in others. Presence of minerals (Ca 2+ ) and dissolved solids (TDS) can induce resistance to dissolution, which can somewhat alter the erosive potential (Featherstone and Lussi 2006, Cochrane, Yuan et al. 2012). 117

Bottled drinking water Fruit juices Energy drinks Soft drinks 4. CONCLUSION The present work has shown that beverages commonly available in Bangladesh have dental erosion potential based on the values of different physicochemical properties affecting enamel dissolution. Besides the low ph, indicative of high possibility for demineralization owing to acidity, the titratable acidity values of certain beverages, especially those of energy drinks, showed greater risks of erosion. However, high levels of calcium and phosphate ions present in soft drinks may also influence the potential for enamel dissolution. Although, the erosion potential of the beverages were estimated based on parameter values reported in established literature, future in vitro studies, planned and initiated, with teeth samples exposed to these samples will be able to determine the actual degree of dental erosion. However, evaluation of dental erosion potential, like this present chemical analyses and future in vitro studies, will serve as the basis for determining the potential erosion risk towards the population of Bangladesh. Finally, creating awareness among general public, health workers, and nutritionists about the dental health hazard attributable to regularly consumed food and beverages is critical to averse forthcoming high prevalence of erosion induced dental diseases and also to improve overall oral health of the population. ACKNOWLEDGEMENT This research was supported by BCEF Academic Research Fund. Table 1: TDS, ph, TA, phosphate and calcium contents of soft drinks, energy drinks, fruit juices and bottled drinking water Sample Total Dissolved Solids (TDS), ppm ph Titratable Acidity (TA), mg/l as CaCO 3 Phosphate (PO 3-4 ), ppm Calcium (Ca ++ ), ppm CocaCola 590.33 2.5 1647.50 555.57 120.24 Fanta 312.67 2.9 1773.75 240.33 30.06 Sprite 230.00 3.1 1490.33 0.11 50.10 Pepsi 521.33 2.9 1663.00 462.50 40.08 Mirinda Orange 330.67 2.9 2356.50 1.30 90.18 7Up 333.33 3.4 2168.00 0.08 30.06 Mountain Dew 275.00 3.0 1572.33 0.68 80.16 RC Cola 416.67 2.7 1534.25 418.50 20.04 Uro Orange 319.50 2.8 1560.00 0.98 60.12 Virgin Red 674.00 2.4 1785.17 1017.67 80.16 Mojo 590.67 2.5 1551.67 2259.67 120.24 Clemon 423.00 3.5 1843.25 0.52 80.16 RC Club Soda 472.00 5.5 1622.25 0.29 0.00 Appy Fizz 618.67 3.5 1921.25 2.31 40.08 Red Bull 832.33 3.5 5283.50 0.16 390.78 Speed 408.33 3.0 2155.83 0.21 70.14 Tiger 284.67 3.1 3321.50 1.24 90.18 Power 290.67 3.2 2519.67 0.64 70.14 SunDrop Mango 664.33 3.5 1308.92 3.09 160.32 Ceres Mango 1279.33 3.7 3810.50 1.93 90.18 Danish Mango 565.67 3.8 1472.50 1.92 120.24 Frooto Mango 618.33 3.4 1601.25 2.33 100.20 Fruitika Mango 502.33 3.9 1134.92 2.52 140.28 Mangolee mango 713.67 3.9 1370.58 0.46 110.22 Shezan Mango 615.33 3.9 1368.00 1.18 150.30 Pran Mango 596.67 3.7 1712.50 0.69 80.16 Aquafina 11.63 7.0 51.50 0.23 3.01 Mum 118.67 7.1 25.75 0.30 32.06 Ifad 46.07 7.2 51.50 0.39 26.05 Acme 50.20 7.3 34.33 0.24 0.00 Evian 234.00 7.8 25.75 0.63 163.33 Spa 325.67 7.1 0.00 3.86 92.18 Fresh 113.83 7.1 25.75 0.24 13.03 Pran 73.00 7.6 25.75 0.16 6.01 Jibon 57.50 4.9 34.33 0.26 15.03 118

(a) (b) (c) (d) (e) Fig. 1: Dental erosion indicating parameters of beverages and bottled drinking water. a) ph, b) TDS, c) TA, d) phosphate, e) calcium 119

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