Dental erosion and dental caries are typical disease causing dental hard tissue damage. Recently, tooth erosion increases have been reported due to the influence of a lot of acidic drinks. Dental caries means the loss of the tooth hard tissue by inorganic acid produced by the oral bacteria¹⁾. Dental erosion means the loss of the irreversible dental hard tissue due to the chemical action of the acid without the involvement of bacteria²⁾.

Dental erosion begins due to the demineralization of the enamel surface. When abrasion action is added, loss of dental hard tissue accelerates and after the dentin is exposed, more severe hemorrhoids get loss. When teeth weakened by erosion, attrition and abrasion can cause serious damage if the combination of action²⁾. Dental erosion, caused by frequent contact between the corrosive acid and tooth surface, can be divided to exogenous and endogenous factors by contact path³⁾.

Endogenous factors, gastric reflux to stomach through esophagus to cause tooth erosion^4-6), could cause serious damage when gastric it contacts on tooth because of low salivary buffering capacity and flow. On exogenous factors, frequent intake of acidic foods and drinks^7-11), acid oral hygiene products¹²⁾, and long-term use of acidic drugs¹³⁾ are the typical examples. In addition, when workers of battery factory exposed to sulfuric acid or workers of galvanizing factory exposed to hydracid chloride, dental erosion occurs¹⁴⁾.

Among many factors that may cause dental erosion, acidic food and beverage is emerging as a new and important concern. In some advanced industrialized countries, since dental erosion problem has emerged, it is argued that when acidic beverage consumption has steadily increased, dental erosion will be more problematic clinically. But various acidic beverage was developed to continue, being able to access more easily, so consumption is increasing day by day. Also, it is a big problem that major consumer groups are children and adolescents¹⁵⁾. It is well known that most of the beverage on the market is acid. In Korea, on a study of Choi and Shin¹⁶⁾, measuring pH of various commercial beverage, which is 158 kinds, Most of beverage, except milk products, showed lower than pH 4.0.

On a study about acidic drinks, When often drinks high acid beverage, erosion may cause on enamel¹⁷⁾, Attin et al.¹⁸⁾ reported that the enamel loss observed in the Coca-Cola and orange juice. Birkhed¹⁹⁾ said about sport beverage, Brunton and Hussain²⁰⁾ reported tea and herb tea, and Sim et al.²¹⁾ reported fermented milk cause dental erosion. Snchez et al.²²⁾ said lower pH beverage you drink, aspect of dental erosion increase. Muller and Gortner²³⁾ reported aspect of enamel demineralization may appear differently depending on the pH of the beverage and kinds of acid of beverage. Maupome et al.¹⁰⁾ said the biggest factor that reduce the strength of the tooth surface when beverage applied to the primary and permanent teeth, if composition of long-time storage and frequent oral intake of drinks appear. Also on a study about degree of acidic beverages, concentration of the carbohydrate, Ca and P concentrations, potential of demineralization, product of the acid, and termination about oral microorganism, Grenby et al.¹¹⁾ reported acid affects more on erosion than caries and proper pH gives more effect on the erosion than pH in beverage. Not only was that the fruity or carbonate-containing mineral in the water-induced erosion²⁴⁾.

On the otherwise, Johansson et al.²⁵⁾ said the longer the retention time of the drink the larger dental erosion increases especially carbonated drinks such as cola is associated on dental erosion. Ahn et al.²⁶⁾ reported when primary teeth specimens immersed in acidic beverages measured by surface micro-hardness reduction in the hourly, surface microhardness decreased like 16.90% after five minutes, 25.11% after ten minutes, and 41.62% after 60 minutes. And among them, the reduction of flavored carbonated beverage was the largest. Also, Lussi et al.⁷⁾ observed surface hardness of personsʼ premolar immersed for 20 minutes to beverage, when compare a before and after beverage treatment, after the treatment dental erosion caused especially on a drink with a fruit acid. Venables et al.⁸⁾ and Hooper et al.⁹⁾ reported the type of beverage that is consumed gives the biggest effect on enamel loss as a result of attaching the removable device on human tooth enamel erosion effect of the drink. In addition, Ahn et al.²⁷⁾ said on a study of erosion of the enamel surface species of soft drinks, the four types of soft drink except for the milk products, caused demineralization of the tooth surface and intensified in accordance with the time of exposure. Additionally, energy drink which has strong recognize as a healthy drink due to ads, sparkling water with low acidity, drinks containing citric acid known to be effective in relieving fatigue, and orange juice is reported has a connection with dental erosion^24,28,29).

Recently, this is a situation that changes in diet and the consumption of various types of signs demand for food increases as per the processing technology improves the standard of living and food development. Among them high caffeine drinks, called ʻenergy drinksʼ have become very popular in teenagers, college students and office workers. Energy drinks are favorites of candidates, college students, and office workers have been lot of stress cause improve concentration and fatigue effects. They are growing rapidly on domestic and foreign markets³⁰⁾.

Domestic previous studies on energy drinks began in earnest at 2003 with research for caffeine-containing foods by Korea Health Industry Development Institute status and display system improvement as the center. As the beverage market aimed at children expands, the dangers of reckless caffeine ingestion in children with drinks on the market were reported in children survey on a drinks with caffeine intake³¹⁾. In recent years, problems caused by the increase of young people who consume energy drinks reported, focus of studies moved high caffeinated beverages to energy drinks. Intake of energy drinks in Seoul middle school students by Ko³²⁾, intake of caffeine drinks with middle school students of Daejeon by Ju³³⁾, intakes of functional beverage in Daegu high school and university students by Moon³⁴⁾ have been reported. Also Kim³⁵⁾ reported on a study of intake of high caffeinated beverages on youth, correct understanding of the high caffeine and taurine, mixed drinks education is desperately needed to young people. Likewise, many studies have been reported on the situation in after 2013, including a high intake of caffeine drinks energy drinks.

Thus, the supply of various kinds of drinks, both qualitative and quantitative expansion has now a lot of people consume on a daily basis. In particular, in many cases growth of children and young people are the main consumers of the drinking frequency reached a level of concern. But most of the studies have been limited to high-caffeine beverage intake that targets a specific layer of empirical research on youth and energy drinks erode tooth situation is almost incomplete.

Therefore, this study was conducted for the purpose of analysis and investigation on the effect of these energy drinks on enamel erosion. First of all selects four kinds of energy drinks commercially available on domestic, analyze acidity, buffering capacity, and the content of the main inorganic component and measure the surface hardness and erosion of the enamel specimens.

1) Tooth and beverage selection

The permanent premolars, did not exceed 2 weeks after extracted for purposes of orthodontics, were observed with the eye. Second select 75 excepting tooth decay, cracks, fractures, abrasion etc. Finally, immersed in distilled water (Daihan Pharm Co., Seoul, Korea) and kept refrigerated. Energy drink used in experiment as an experiment group was four kinds of products have high market share on its market and distilled water was a control group (Table 1).

2) Specimen fabrication

Put extracted premolar in 5% NaOCl solution for 24 hours, remove the surface of soft tissue, cleaned it on a distilled water. Cut horizontally at the enamel-dentin junction removing the root, the enamel fragments were collected each size of 4×4 mm from 75 premolar crown, using cutting disc. After that, diameter 10 mm, height 10 mm of epoxy resin mold fabricated cylindrical position enamel surface is perpendicular to the long axis of the cylindrical and Only exposed enamel surface was embedded. To make the flat surface of the exposed enamel specimens prepared used by #80, #600, #1,000, #1,500, #2,000 grit sand paper (Matador, Edinburgh, Germany) on ground.

1) Analysis of energy drinks

(1) Acidity (pH) and the buffering capacity measurement

The solution was left at room temperature for 6 hours and dispensed 50 ml beaker. After correcting the measured value of the pH meter (P25; pH Meter EcoMet, Seoul, Korea), the pH was measured in each group. Buffering capacity is added by 0.1 ml a 1 M NaOH to 50 ml drink and uniformly mixed with a electronic stirrer and measuring value of the stabilized pH, measured the NaOH amount varies when the pH of the beverage turns 5.5 to 7.0. The acidity and buffering capacity three times measured in the same way by the average value was calculated.

(2) Calcium, phosphorus concentration measurement

In calcium concentration is Inductively Coupled Plasma-Atomic Emission Spectroscopy (Optima 7300DV: Perkin Elmer, Seoul, Korea), the concentration is quantitatively analyzed in the Ion Chromatography (Agilent LC-1100 Series; High Performance Liquid Chromatography, Santa Clara, CA, USA).

2) Surface microhardness measurements

The polished sample is then added to the load of the vertical surface in 10 seconds 200 gm in enamel microhardness meter (HMV-2; Shimadzu, Kyoto, Japan) per specimen were measured surface microhardness (Vickerʼs hardness number, VHN) in three portions. After, 75 specimens, enamel surface hardness 280∼320, were selected and assigned to each 5 group equally.

3) Test after an immersion and before immersion in energy drinks

(1) Immersion on energy drinks

Drink was opened immediately prior to immersion of the specimen and was used to measure pH immediately prior to use for use in maintaining the same pH. Each beverage was dispensed using the same vessel by 50 ml each drink was induced for 30 minutes soak erosion.

(2) Surface microhardness measurements

Specimens, immersed in a drink to recover when the 30 minutes have elapsed, cleaned it with distilled water for 1 minute. And measured a surface hardness at three adjacent region who measured before treatment areas using surface micro-hardness tester.

(3) Observation and analysis though a scanning electron microscope

After exposed specimens were washed with distilled water, they were dehydrated with a graded ethanol series for 15 minutes in each step. After that, they were dried with a critical point dryer (HCP-2; Hitachi, Tokyo, Japan). After that, they were coated with platinum in thickness of 20 nm by using the ion sputter (E-1030; Hithchi) and observed at 10 kV with a SEM (S-4700; Hitachi). And SEM analysis of the surface roughness, cracking of the surface, the expose of the fistula, which was determined in four of the items of the minerals lost. Roughness of the surface was determined by the degree of unevenness eye bore, a crack in the surface took on the basis of determining the presence or absence of holes in the exposed surface of the tooth is determined, the cracks of the tooth surface fistula. Inorganic dissipation took the wear of the teeth on the basis of the judgment. Show how observation is as follows (Table 2).

4) Statistical analysis

The paired t-test was used to compare the enamel surface hardness before and 30 minutes after immersion of the enamel specimens into the drink. To compare the average surface hardness of enamel according to the drink groups, used one-way ANOVA. Dunnett T3 was used for post-test. Statistical analyzes were analyzed using IBM SPSS Statistics 19.0 (IBM Co., Armonk, NY, USA) statistical program.

1) Acidity and buffering capacity

Four kinds used in the experiment (Hot6 [Lotte Chilsung Co., Seoul, Korea], Red Bull [Red bull GmbH Co., Vienna, Austria], Burn Intense [Coca-Cola Co., Georgia, Atlanta, USA], Bolt Energy [Haitai Co., Seoul, Korea]), energy drinks all of citric acid had been added. Acidity of energy drink ʻBurn Intenseʼ was the lowest as 2.78±0.01 highest on distilled water as 6.475± 0.01. ʻBurn Intenseʼ buffering capacity was 3.48±0.155 at pH 5.5, 1.88±0.15 at pH 7.0 which is the highest, and ʻHot6ʼ was 1.71±0.37, 1.23±0.35 on each of it showing the lowest points (Table 3).

2) Ca, P content in energy drink

Ca content on energy drink was the highest at ʻVolt Energyʼ as 77.21±2.70 mg/kg, the lowest at ʻHot6ʼ as 0.98±0.05 mg/kg. P content was the highest on ʻHot6ʼ as 1.34±0.05 mg/kg, ʻRed Bullʼ 0.49±0.02 mg/kg, ʻBurn Intenseʼ 0.41±0.01 mg/kg in the order (Table 4).

Before immersion, enamel surface hardness was 301.94 VHN on distilled water, 303.52∼307.96 VHN on energy drink so there were no significant differences between the groups. But after immersing in energy drink for 30 minutes, enamel surface hardness was significantly decreased in all groups compared statistically before immersion (p＜0.01, Table 5).

After immersing in energy drink for 30 minutes was the lowest on ʻRed Bullʼ as 66.65±35.60 VHN, ʻVolt Energyʼ as 61.96±31.42 VHN, ʻBurn Intenseʼ 58.53±24.84 VHN, ʻHot6ʼ 53.99±60.26 VHN, ʻdistilled waterʼ 1.65±2.05 VHN in the order (p＜0.01, Table 5).

Distilled water, the control group, showed significant difference with the experimental group. ʻHot6ʼ was－53.24000, ʻBurn Intenseʼ－57.78667, ʻRed Bullʼ－65.90667, ʻVolt Energyʼ－61.21333, all were statistically significant. But there was no significant difference between the groups (Table 6).

1) SEM observation

Before and after immersion in distilled water was found to be flat smooth surface without lost. ʻRed Bullʼ and ʻHot6ʼ observed similar pattern, after immersion due to erosion surface was rough could find fine crack between crystals. On ʻVolt Energyʼ, erosion is worse than ʻRed Bullʼ and ʻHot6ʼ recessed fistula was partially observed. On ʻBurn Intenseʼ case, compared to all the groups, surface is badly eroded could observe on all enamel surface crack and round, deep indented fistula (Fig. 1).

2) SEM analysis

The control group, distilled water, got 1 point on roughness and fistula, and 0 point in each crack and mineral loss. In the experimental group, ʻBurn Intenseʼ showed the highest point, 3, in all four contents. ʻVolt Energyʼ, ʻHot6ʼ, ʻRed Bullʼ was in order (Table 7).

Dental erosion is the gradual loss of tooth hard tissue and generated by the chemical process regardless of the activity of the bacteria. Dental erosion is distinguished from abrasion and attrition. Attrition is a physical phenomenon caused by the contact between teeth and abrasion is a pathological phenomenon caused by the abnormal mechanical action³⁶⁾. Clinical aspects of dental erosion is shown by the number of teeth by bilateral, does not represent a rough surface or chalk that is accompanied by decalcification process, lubricant and peripheral surface of the enamel is smooth transition to the normal surface is known that there is no color change³⁷⁾. Also, dental erosion is caused by direct contact between tooth surfaces and acid which demineralizes tooth surfaces and without formating lesions below the surface, enamel rods peripheral places get softened. In addition, whereas dental erosion is a phenomena at the tooth surface, dental caries is characterized as demineralization which starts from by the lower surface and formating cavity by the action of acid generated by microorganism in dental plaque³⁸⁾.

Research that acidic fruit juices and drinks cause tooth erosion has been reported in the early years. In early 1970s, since Levine³⁹⁾ reported increase of drinking fruit juice could be a clinical problems causing dental erosion, acidic drinks have been more trend to diversification and the emergence of new consumption surged by various fruit juices and sports drinks. Most of this drinks pH is 2∼4, strong acid⁴⁰⁾, Rytomaa et al.⁴¹⁾ reported critical pH of enamel dissolution occurs is pH 5.5, and acid food that is lower than pH 4 is more dangerous could cause more dental erosion. Gregory-Head and Curtis⁴²⁾ said the solubility of teeth increases 7∼8 fold whenever the one (pH 1.0) from the normal pH of the mouth which is pH 6.5 gets lower. In addition to the factors affecting dental erosion is a drink of flourine, calcium and phosphorus content as well as the type of acid and titratable acidity. As an affect of these factors, dental erosion occurs or may cause remineralization⁴³⁾. In this study, pH of the beverage, buffering capacity, and measured the concentration of calcium and phosphorus considering these factors. Also except for control group, energy drinks used in the experiment, such as Red Bull, Burn Intense, Volt Energy, Hot6, was respectively 3.23, 2.78, 2.98, 3.43 and was consistent with reports of previous investigators, so that it can be fully demineralized.

Like a pH of beverage, buffering capacity is also a important variables. Edwards et al.⁴⁴⁾ defined a buffering capacity as a the nature of the acidic drink to resist change in pH. Tahmassebi et al.⁴⁵⁾ said beverage acidity can be seen in the total amount of the acid is possible, more accurately show the erosion of the actual drink because the pH of the beverage does not describe as to present only the undissociated acid value of the hydrogen ion concentration contained in the beverage. Grobler and van der Horst⁴⁶⁾ insisted because of the ability to resist changes in pH of the beverage by the saliva buffer capacity, the acidity in the mouth is longer maintained, and thus play an important role in the erosion process. Also, (thus), Cairns et al.⁴⁷⁾ said in examination of 4 species of drinks, showing significant resistance on raising the pH is cause of high internal buffering capacity. Larsen and Nyvad⁴⁸⁾ said it could cause more high erosion when acidic drink has lower pH or has high buffering capacity. In this study, evaluated buffering capacity by the amount of NaOH needed the pH of the beverage is to reach up to 5.5 and 7.0. And found out that buffering capacity which was highest on among 4 species of energy drink was ʻBurn Intenseʼ that has lowest pH to reach pH 5.5 and pH 7.0 needed NaOH amount was 3.48 ml, 1.88 ml. And most decreased on surface hardness values after 30min, causing more erosion when buffering capacity is high, same results with Larsen and Nyvadʼs study⁴⁸⁾.

There have been many previous studies that the addition of calcium and phosphorus in acidic beverages inhibit erosion. Larsen and Nyvad⁴⁸⁾ reported erision didnʼt caused on orange juice which was pH 4.0, added calcium (40 mmol/L), phosphorus (30 mmol/L). Hooper et al.⁴⁹⁾ reported in in situ, erosion inhibits in comparison with a control group that calcium and phosphorus are added to soft drinks has not been added. Based on these findings, it seems like calcium and phosphorus is a key role on inhibiting erosion but on this study ʻVolt Energy (77.21 mg/kg)ʼ that contained lot of calcium, ʻHot6 (1.34 mg/kg)ʼ that has lot of phosphorus caused a erosion showed a difference with previous studies. These result could inferred ʻVolt Energyʼ contains calcium but no phosphorus, otherwise ʻHot6ʼ has phosphorus but not substantially included calcium so it may be the result of a interaction of calcium and phosphorus. Therefore, studies on the interaction on the calcium and phosphorus corrosion inhibition may be necessary in the future.

On the otherwise, a method for analyzing the state of tooth erosion usually used surface microhardness, SEM, microradiography, digital image analysis, chemical analysis, iodine permeability measurements, atomic force microscopy⁵⁰⁾. Surface microhardness used in this experiment is effective to measure the change in the surface microstructure as a method for indirectly measuring the degree of demineralization of the initial lesions. Featherstone and Mellberg¹⁾ said on a surface micro-hardness measurements are sensitive enough to 50 μm within the depth. Lussi et al.⁷⁾ immersed a premolar on acidic drink about 20 minutes to observe a surface hardness before and after beverage processing. Reported dental erosion caused after processing, and on other many studies reported a big connection between pH of drinks and dental erosion^17,21). Lee et al.⁵¹⁾ said four kinds of surface hardness after immersion than 10 minutes to drink in the experiment of immersing the orange juice that has been reduced from 7.2% to 11.2%. Maupome et al.¹⁰⁾ reported about hardness variation on a differences in pH beverage treatment times after plaque formated in normal enamel, enamel hardness gets lower when 1 day intake frequency increased. Youn⁵²⁾, on a study of enamel erosion by some commercial drinks, said showing a large tooth erosion in a mixed drink carbonated beverages group than the group of low pH is considered to be under the influence of drink drinks there which contained in acid drinks. On Van Eygen et al.ʼs coke test⁵³⁾, when immersed for 20 minutes, 3 times in a day for a week on drinks, and immersed on artificial saliva for 1 hour, enamel surface hardness shown to be statistically significant decrease. Also, at Youn et al.ʼs study⁵⁴⁾, when applied to beverages other than the 10 kinds of control group to the normal enamel, enamel surface hardness before immersing in drinks has no significant difference, but after 10 minutes immersed in drink significantly in both the test and control groups was reduced. On this study, enamel surface hardness before immersing in energy drink was 301.94 VHN on distilled water, 303.52∼307.96 VHN on energy drink, has no significant difference. But after immersing in energy drink for 30 minutes, enamel surface hardness is decreased by a statistically in all groups compared before immersion and prior studies showed similar results, but the difference in materials and methods.

Scanning electron microscopy is shaping the surface structure of the sample image which can be seen by an optical microscope at a much higher resolution by using an electron beam. It is possible to see the fine region having a size smaller than the wavelength of visible light through the electron beam is focused by a magnetic lens⁵⁵⁾. In addition, through the image that has taken from SEM, since analysis or useful to measure the feature cannot be seen with an optical microscope was used in this study. On a study of erosion of enamel by some commercial drinks, Youn⁵²⁾ said mixed drink groups and soft drink groups of normal enamel and artificial carious enamel showed a lot of rough surface due to erosion, decisions have been arranged very irregularly observed in finely crushed form. On this study, except for a case of immersed in distilled water, control group, all experiment group, energy drink, showed erosion similar with Youn⁵²⁾ result at ʻBurn Intenseʼ which has highest pH. Grando et al.⁵⁶⁾ said on a case of immersed enamel on 12 hours at soft drink groups, could find out destroy of sheath and head of enamel rod, and sulcus between enamel sheath and head. But on this study, couldnʼt find sheath and head of enamel rod after immersion on enamel drink. The previous studies are thought to have occurred less erosion because of observing the surface of the immersion will constantly immersed for 12 hours soda. This study was for a short time of 30 minutes in the energy drink. On a Eisenburger et al.ʼs study⁵⁷⁾, 3% citric acid solution and then immersed for 2 hours in a result of observation by SEM, there was irregular crystals which were arranged in a predetermined direction and determination of the type that a flat carpet was looked for covering the surface aspect. In case of energy drinks in the present study, there was rough and irregular crystal which is aligned in a predetermined direction with a fine crack and forms of decision-toed soap bubbles are showing similar results and aspects covering the whole surface.

On the otherwise, Kim⁵⁸⁾ said Coca-Cola, when orange juice and sports drinks after analysis of the enamel surface treatment using SEM, Roughness, exposure and mineral loss of fistula appears two or more points in all groups on a experimental study about influence carbonated beverage intake on tooth. The surface both before and after immersion in distilled water was evaluated by the flat smooth points where no lost, also on this study. But on a case of ʻRed Bullʼ and ʻHot6ʼ, energy drinks are then immersed between 1∼2 points with a view to fine cracks between the crystal surface was slightly rough, because of the erosion. But on a ʻVolt Energyʼ, erosion was hard than ʻRed Bullʼ and ʻHot6ʼ, partially recorded the recessed average two-point which is fistula observed. Especially, ʻBurn Intenseʼ, Average three points are badly eroded surface compared to all groups was observed in the form of a rounded and deeply indented fistula enamel cracks throughout the first half.

The most effective way to prevent dental erosion is to reduce the chance of contact with acid. Also, to reduce oral residence time and the frequency of acidic food intake and to increase the salivary flow rate may help reduce erosion. These tooth erosion due to increased food should be placed on prevention rather than treatment emphasis. Tell hazards and should promote an acidic beverage ever developed alternative beverages to reduce the intake of acidic foods. Especially the children, while remaining to prevent the intake of drinking water in the mouth for a long time thought to be, above all, it is important to be educated²⁷⁾.

Taken together, the above results between energy drinks there was no statistically significant difference, but showed a significant difference when compared with distilled water. Also became a cause tooth erosion in all energy drinks in a scanning electron microscope observation and analysis, especially in the most severe erosion was observed with the lowest pH, Burn Intense. Therefore, it is considered that the general public for energy drinks that can affect the tooth erosion to provide various oral health education and information in order to have the proper recognition and reasonable dental care.

To find out the effect of commercially available energy drinks on tooth enamel erosion, analyzed pH, buffering capacity, and the content of some of the inorganic components selecting 4 energy drinks that has high affinity. In addition, by observing the degree of erosion before and after immersion in energy drink by surface microhardness and SEM the results were as follows.

1. Acidity of energy drink ʻBurn Intenseʼ was the lowest as 2.78±0.01, highest on distilled water as 6.475±0.01. ʻBurn Intenseʼ buffering capacity was 3.48±0.155 at pH 5.5, 1.88±0.15 at pH 7.0 which is the highest, and ʻHot6ʼ was 1.71±0.37, 1.23±0.35 on each of it showing the lowest points.

2. Ca content on energy drink was the highest at ʻVolt Energyʼ, the lowest at ʻHot6ʼ. P content was the highest on ʻ Hot6ʼ and detected at ʻRed Bullʼ.

3. Enamel surface hardness variation of the energy drinks before and after immersion showed rapid decrease at ʻRed Bullʼ, and ʻVolt Energyʼ, ʻBurn Intenseʼ, ʻHot6ʼ was in order. Distilled water, the control group, showed significant difference with the experimental group (p＜0.05). But there was no significant difference between energy drinks.

4. At SEM observation and analysis, ʻBurn Intenseʼ was the most severe demineralization, ʻVolt Energyʼ, ʻHot6ʼ, ʻRed Bullʼ, distilled water was in order.

In the above results, low acidity or containing citric acid energy drink intake on normal enamel could reduce the hardness of the tooth surface able to deteriorate the tooth damage.