Evaluation of the effect of food and beverages on enamel and restorative materials by SEM and...

Evaluation of the Effect of Food and Beverages on Enameland Restorative Materials by SEM and Fourier TransformInfrared SpectroscopyMUSTAFA ERHAN SARI,1* ALIYE GEDIZ ERTURK,2 ALP ERDIN KOYUTURK,1 AND YUNUS BEKDEMIR3

1Department of Pediatric Dentistry Samsun, Ondokuz Mayıs University Faculty of Dentistry, Turkey2Department of Organic Chemical, Assistant Prof. Ordu University Faculty of Literature and Sciences, Ordu, Turkey3Department of Molecular biology and genetics, Basari University, Samsun, Turkey

KEY WORDS erosive; foods; restorative materials; ATR-FTIR; enamel; SEM

ABSTRACT Objectives To examine different types of restorative materials used in childrenas well as primary and permanent teeth enamel when affected by erosive foods. Materials andMethod Buttermilk, fruit yoghurt, Coca-cola, fruit juice, Filtek Z-250, Dyract Extra, Fuji II LC,and Fuji IX and tooth enamel were used. Measurements were performed on 1-day, 1-week,1-month, 3-month, 6-month time periods by using ATR-FTIR technique and surface of the speci-mens were examined with SEM. Results Permanent tooth showed the least change amonghuman tooth samples when compared to restorative materials. Among filler materials, the mostchange was observed in Fuji IX. In terms of beverages the most changes on absorption peaksobtained from spectra were seen on the samples held in Coca-Cola and orange-juice. ConclusionThe exposure of human enamel and restorative materials to acidic drinks may accelerate thedegradation process and so reduce the life time of filler materials at equivalent integral exposuretimes longer than three months. Clinical Relevance Erosive foods and drinks having acidicpotential destroy not only tooth enamel but also restorative materials. Microsc. Res. Tech. 77:79–90, 2014. VC 2013 Wiley Periodicals, Inc.

INTRODUCTION

The relationship of dental erosion, resulting in animportant destruction on tooth surface with foods anddrinks such as fruit juice, energy drinks, and cola drinkshaving acidic potential have been reported (Grippo et al.,2004). Highly refined acidic beverages, sweetened withcarbohydrates has been reported to cause morphologicalchanges on the surface of the enamel (Wongkhanteeet al., 2006). It is thought that the consumption of foodssuch as fruit, fruit juice, and yoghurt can cause erosiondue to acidity (Zero, 1996). It is declared that teeth ero-sion not only affects the enamel but also results in severeundesirable cases such as the extreme sensitivity of den-tin, opening of pulp, tooth breakage (Jarvinen et al.,1991; Grobler et al., 1990).

The treatment of eroded teeth without material lossthanks to the minimally invasive techniques is possi-ble (Lambrechts et al., 1996). To this goal the use ofglass ionomer cements and compomers are preferredespecially on children with fluoride release peculiarity(Croll and Nicholson, 2002; Jitpukdeebodintra et al.,2010; Hunter et al., 2000).

Enamel and dentin are the two basic elements form-ing the tooth’s hard tissue. Enamel is the hardesttissue covering on the surface of the tooth crown (Rob-inson et al., 2000). Enamel tissue consists of 95% (wt)inorganic mineralized material, 1% (wt) organic, and4% (wt) water by weight. A large part of the inorganicstructure is formed by hydroxyapatite (HA) crystals;the organic structure is formed by collagen. 85% (vol)

of enamel is inorganic by volume. The remaining partsconsist of water, lipid, and protein. Histologically, pris-matic structure is observed in the enamel tissue. Thisprisms stretch to the surface from enamel dentin bor-der and is similar to cylinders in shape. Protein andlipid are located between in the interprismatic room,with the water in the structure of the enamel prismsand crystals. As these properties of the enamel tissue,it contains more inorganic material than dentin (Stav-rianos et al., 2010).

HA (Ca10 (PO4)6 (OH)2) crystals form a tissue thatis well defined both morphologically and histologically.Primary teeth enamel tissue consists of 92–93% (wt)inorganic material, 4% (wt) organic material, and 3%(wt) water. Primary teeth enamel formation time ishalf the duration of the permanent formation. Its inor-ganic structure is formed by 90% (wt) of the crystallinecalcium phosphate (Ca3(PO4)2), along with, CO3

22, F2,and Mg12 ions. Enamel crystals as all HA crystals arein a dynamic structure, and there is continuous ionexchange. For example, Ca12 can be replaced with

Additional Supporting Information may be found in the online version of thisarticle.

*Correspondence to: Mustafa Erhan Sari; Department of Pediatric DentistrySamsun, Ondokuz Mayıs University Faculty of Dentistry, Turkey. E-mail:[email protected]

Received 27 August 2013; accepted in revised form 26 October 2013REVIEW EDITOR: Prof. Alberto Diaspro

DOI 10.1002/jemt.22315Published online 12 November 2013 in Wiley Online Library(wileyonlinelibrary.com).

VVC 2013 WILEY PERIODICALS, INC.

MICROSCOPY RESEARCH AND TECHNIQUE 77:79–90 (2014)

Sr12, OH2 with F2; PO423 with CO3

22 and so forth,with the new joins joining tissue. Sodium and magne-sium are collected around the crystals (Robinson et al.,2000).

The enamel of primary teeth is anatomically differ-ent from permanent teeth. Therefore, the thickness ofthe enamel of primary teeth is half the size of the per-manent teeth. Thereby, primary teeth are more brittlethan permanent teeth. There are two types of enamelon primary teeth. The first of these is the inner layeroccurred in intrauterine life, the second one is theouter layer occurred immediately after birth. The pre-natal inner layer is more homogenous than the outerlayer. Postnatal layer shows more calcification andhave irregular prisms directions (Shellis, 1998).

Among the spectroscopic techniques, infrared (IR)spectrometry is a versatile technique used in the deter-mination of qualitative and quantitative determina-tion of different types of molecules. Especially MID-IRoffers kinetic and structural information about reac-tion components of organic and biochemical substanceswithout any special sample preparation or applicationof complex chemometric methods for analysis or expen-sive modifications to the reactor configuration (Her-geth, 1997; Kammona et al., 1999). Attenuated totalreflection mode of fourier-transform infrared spectros-copy (ATR-FTIR) is a well-established, rapid and non-destructive method for determining the chemicalcomposition of materials based on their chemical bond-ing. It is particularly useful for polymeric substances,which tend to have more variation in chemical bondingthan in elemental composition. ATR-FTIR achievessurface specificity by reflecting the infrared beamwithin a crystal to generate an evanescent wave at thesurface, direct contact with the surface of sample.Recent advances in sensing and signal transfer tech-nologies have enabled the utilization of ATR-FTIRspectroscopy for remote, real-time reaction monitoringof chemical reactions (Smith, 1996).

FTIR is usually used in restorative dentistry mainlyto measure the degree of conversion undergone by theresin matrix upon photo curing (Thorat et al., 2012).However, as we have considered that the pH of the

drinks actually triggers chemical degradation of thedental materials, FTIR was carried out to monitor thechanges of chemical composition of materials by meansof shifts of peak position with changing acidity. Suchan extensively and qualitative work depended on FTIRanalysis that is provided for all the considered materi-als in the literature has not yet. Therefore, we nowreport the effect of exposure to foods and drinks withdifferent erosive potential on four restorative materi-als and on two kinds of tooth enamel for different timeperiods by ATR-FTIR.

Today, the number of the studies related with theimpact of acidic foods and beverages consumed by chil-dren on restorative materials is very limited. Con-sumption of acidic drinks can degrade both teeth andrestorative materials. A significant reduction on sur-face hardness of dental restorative materials afterimmersion in coke and fruit juices materials wasreported (Aliping-McKenzie et al., 2004). While cokecontains large quantities of phosphoric acid, orangejuice contains citric acid. These acids may lead toincrease in water uptake and reduce the properties ofthe dental restorative composites. The aim of thisstudy is to examine if the enamel of primary and per-manent teeth and the organic structure of differenttypes of restorative materials used in children den-tistry are affected from erosive foods or not.

MATERIALS AND METHODS

The materials examined in this study are listed inTable 1, the eroding products used in this study areshown in Table 2.

Pieces of sample from each material were prepared.Teflon molds were made to obtain these samples. Slotswere created on Teflon molds as 5 mm in diameter and2 mm in height. The restorative materials [FiltekZ-250 (3M/ESPE, St. Paul, MN), Dyract Extra (Dents-ply DeTrey, Konstanz, Germany), Fuji II LC and FujiIX (GC Corporation, Tokyo, Japan)] were prepared andplaced into the slots as recommended by the manufac-turer. Fuji II LC and Fuji IX materials were used incapsule form. The samples were removed from themolds after the manufacturer’s recommended period oftime (20 sec) to complete the chemical polymerization.The dental restorative materials were polymerizedwith Free Light II (1200 mW/cm2) LED light device(480-nm wavelength) by applying to this glass on theperiod of time recommended by the manufacturer.Light intensity was checked with regular intervalsduring the polymerization of the samples with lightwith Curing Radiometer HILUX Curing Light Meter /

TABLE 1. The dental restorative materials examined in this study

Product type Composition Batch number

Resin composite (Filtek Z-250) UDMA, Bis-GMA, BIS-EMA, TEGDMA, zirco-nia/ silica filler

55144

Resin-modified glass ionomer cement(Fuji II LC)

Fluoro-alumino-silicate glass Polyacrylic acid,2-hydroxyethyl methacrylate (HEMA), dime-thacrylate, camphorquinone, water

705161

Traditional glass ionomer cement (Fuji IX) Flouro-Alumino silicate, polyacrylic acid,acrylic-itaconic acid, acrylic-maleic acid.

703271

Polyacid-modified composite (Dyract Extra) UDMA, TEGDMA,TCB, BHT, EDMA, Trime-thacrylte resins, strontium fluoride, ironoxide and titanium dioxide

0808000022

TABLE 2. The eroding products used in this study

Product type Manufacturer pH

Coca-Cola Coca cola 2.74Orange juice Ulker 3.75Buttermilk Ulker 4.05Strawberry Yoghurt Ulker 4.850.9% isotonic sodium chloride Biosel 7.20

80 M.E. SARI ET AL.

Microscopy Research and Technique

Benlio�glu TURKEY) In addition, during the photopoly-merization, to prevent the other samples from under-going additional exposure to light metal washers wereused which ensured that only the region of light to beapplied. Samples removed from the mold were sandedin the order with 600–800-1000–1200 grit polishingsandpaper. To complete the polymerization of the sam-

ples they were suspended in 36.5–37�C incubatordevice (Core EN - 120, Ankara, Turkey) for 24 h.

Permanent third molar and second milk molarswithout caries were used in the study. Debris layer onteeth was removed with a rubber brush and pumice.Teeth were separated from the cervical region bymeans of diamond blade. Then, tissue was removed

Fig. 1. Representative SEM pictures of surface changes in Primary teeth at baseline (a) 3300, Coca-Cola (3 months) (b) 3300, Coca-Cola (6 months) (c) 3300, orange juice (3 months) (d) 3300 and(6 months) (e) 3300.

Fig. 2. Representative SEM surface changes in Permanent teeth at baseline (a) 3300, Coca-Cola(3 months) (b) 3300, Coca-Cola (6 months) (c) 3300, orange juice (3 months) (d) 3300 and (6 months)(e) 3300.

EROSIVE AGING OF DENTAL MATERIALS 81


from the triple middle region as 5 3 5 mm2. Thesesquare specimens were then embedded into Teflondiscs. The enamel surfaces of teeth embedded weresandpapered in order with 600–800-1000–1200 gritpaper. Hundred and fifty samples were prepared bothprimary and permanent teeth.

To quantify the erosive potential of the different foodand beverages the pH values were measured using apH-meter (Knick pH-meter 765 Calimatic, Berlin,Germany).

This study hypothesized that a child’s daily consump-tion of 330-mL drink. Amount of the beverage in contactwith the materials was considered about 8.25 mL ineach sip and the materials came into contact with thebeverage during 10 sec. The materials exposed to bever-age was washed with distilled water to simulate contactwith saliva during 10 sec and thus the one cycle wascompleted. This cycle was repeated 40 times (8.25 mL3 40 5 330 mL) in a day. The materials were stored indistilled water in �37

�C incubator until the next day.

In order to verify the conversion of the chemical com-positions of the materials, ATR-FTIR was used for allmaterials at room temperature. ATR-FTIR measure-ments of the samples prepared were made with thespectro meter VERTEX 80 V (Bruker, Germany). Itwas studied with six different materials held in fourdifferent beverages at five different time periods. Thesamples were measured in the wavenumber range of4000–670 cm21 of each time on ATR-FTIR diamondsurface using a discrimination power 4 cm21 and aver-aging 32 scans for each spectrum. To minimize somenoise in the spectra signal from water vapor and carbondioxide gas present in the air, the spectra wereacquired after the interior of spectrometer was main-tained with dry air for 20 min. The received infraredspectra of samples were reported as percentage trans-mittance values as a function of wave number. Thestudy was made with four different beverages (butter-milk, fruit yoghurt, Coca-cola, and fruit juice) for fourrestorative materials and two native human dental tis-sues. Each sample at the baseline (the previous state ofthe samples not treated with any beverage), at the endof 1 day, 1 week, 1 month, 3 month, and 6 month peri-ods ATR-FTIR measurements were performed.

All specimens were then mounted on a metal stuband coated with gold by means of a sputter coater

Polaron SC500 (VC Microtech, East Sussex, England).SEM analysis using a Philips XL 30 (JEOL JSM 6400LV, Tokyo, Japan) scanning electron microscope withexamine surface morphological changes of the materi-als. The machine was operated at 30-KV beam acceler-ation and the surface was generally viewed at amagnification of 3003.

RESULTS AND DISCUSSIONGeneral Considerations on Combined ATR-FTIR

and SEM Analysis

Spectra obtained from the beginning of each periodwere evaluated on the basis of 3- and 6-month studyresults. At the measurements carried out withATR-FTIR, the materials exposed to drinks have newdifferences in chemical groups like sliding in the peakpositions, the formation of new peaks modification ofthe intensity of some peaks in either decreasing orincreasing direction in intensity. The spectra obtainedof each period were compared. Very large changeswere observed in the 3 and 6 months periods. However,on the periods of 1 day, 1 week, and 1 month whenspectra were compared with respect to location andintensity of peaks no significant difference wasobserved according to the initial peaks significantly.For this reason, the assessments were made on thebasis of the results of initial, 3 and 6 month. The ATR-FTIR results are supported by the SEM analysis of thesample. The samples immersed in Coca-Cola andorange juice showed the deterioration in the surfacestructure in SEM analysis of 3 and 6 months.

Primary Tooth and Permanent Tooth

The SEM analysis of primary and permanent teethare shown in Figure 1 and Figure 2, respectively. Thespectrum for primary and permanent teeth areobserved in Figure 7 and Figure 8, respectively. Theenamel of primary and permanent teeth have the simi-lar organic and inorganic structure. Already the spec-tra obtained for the permanent teeth and primaryteeth are very similar to each other. The wave numberof functional groups found in the human enamel aregiven in Table 3 (Bachmann et al., 2003; Muller et al.,2008; Fattibene et al., 2005).

When Figures 7 and 8 are examined, according toTable 3, wide band at 3600–3100 cm21 can be thoughtto have signals belonging to water entering to the struc-ture as well as belonging to HA forming a large portionof the tooth structure, it also has signs of organic poly-peptides (amide NAH � 3310 cm21) forming theorganic structure of teeth. However, it can be said thata lot of bands appear, masked by the broad water bandin this region; these bands are assigned to amide I, II,and C-H stretching modes (Prakki et al., 2005; Bach-mann et al., 2003). In Figure 7, while the peaks at 1652,1645 cm21 pointing to amide carbonyl (C@O), the signs(1638, 1655 cm21) belonging to amide carbonyl (C@O)in Figure 10 is much stronger as primary teeth is richin protein than the permanent teeth (Chlopek, 2009).The signals coming at 1032 cm21 can correspond to thesignal of the apatite (P-O band). In addition, the peaksat 988, 961, 874, and 660 cm21 in Figure 10 and thepeaks at 1032, 1035, 992 cm21 in Figure 8 are due tothe PO4

32 or CO322 groups (Ito et al., 2005; Ten Cate

TABLE 3. Absorption bands (range) of chemical components presentin human enamel (Bachmann et al., 2003; Fattibene et al., 2005)

Chemical componentsAbsorption bands

(cm21)

apatite OH2 3570H2O 3550–2900CO3

22 and organic material 1544 and1530–1380

PO432 1170–930

CO322 876

OH2 749PO4

32 650–520PO4

32 469amide NH2 or NH stretching

with H bonding3550–3420

or 3450–3320,3200–3050

NAH bending (2.amide band) 1640–1600amide C@O (1.amide band) 1690–1650aliphatic CAH 2960–2850

82 M.E. SARI ET AL.


and Imfeld, 1996). As it seen from the spectrums, thereis no an intense change of primary teeth and perma-nent teeth, except an intense water absorption.

In the previous works, the effects of surface soften-ing and enamel loss caused by acidic soft drinks havebeen investigated. Especially, erosive effects of softdrinks with citric acid caused to dissolution and soften-

ing of human enamel. At lower pH, the erosive soften-ing of human enamel increases (Ten Cate and Imfeld,1996; Barbour et al., 2003). Different acids interactedwith HA surfaces (Hannig et al., 2010). Mono-, di-, andtricarboxylic acids chemically adsorbed onto theenamel surface and increased dissolution of Ca21 andPO4

32 ions out of the HA surface (Hannig et al., 2005).

Fig. 3. Representative SEM surface changes in Filtek Z-250 at baseline (a) 3300, Coca-Cola (3 months)(b) 3300, Coca-Cola (6 months) (c) 3300, orange juice (3 months) (d) 3300 and (6 months) (e) x300.

Fig. 4. Representative SEM surface changes in Dyract Extra at baseline (a) 3300, Coca-Cola(3 months) (b) 3300, Coca-Cola (6 months) (c) 3300, orange juice (3 months) (d) 3300 and (6 months)(e) 3300.



Acid anions can build up insoluble salts, for example,calcium citrate with Ca21 ions. And also the dissoci-ated acids build up chelate complexes with the Ca21

ions of HA surface (Featherstone and Lussi, 2006). Thenoncarboxylic acids (ascorbic acid phosphoric acid)showed the strongest erosion effects in vitro on humandental enamel (Yoshida et al., 2001).

Filtek Z-250

The spectrum of Filtek Z-250 is observed in Figure9. The SEM analysis of Filtek Z-250 is shown in Figure3. It is expected that the restorative materials, initialpolymeric structures will be hydrolysis and new occur-ring functional groups will give the different peaks dueto pH of the beverages used in the study (Freund and

Fig. 5. Representative SEM surface changes in Fuji II LC at baseline (a) 3300, Coca-Cola (3 months)(b) 3300, Coca-Cola (6 months) (c) 3300, orange juice (3 months) (d) 3300 and (6 months) (e) 3300.

Fig. 6. Representative SEM surface changes in Fuji IX at baseline (a) 3300, Coca-Cola (3 months) (b)3300, Coca-Cola (6 months) (c) 3300, orange juice (3 months) (d) 3300 and (6 months) (e) 3300.

84 M.E. SARI ET AL.


Munksgaard, 1990; Moszner et al., 2005). Therefore,the open shapes of the monomers on the proposedstructure in Filtek Z-250 and fragmentation productswere shown in Supporting Information Figure S1(Finer, 2000). The monomers used in the formation ofFiltek Z-250 polymer are Bis-GMA (2,2-bis[4-(20-hydroxy-30-methacryloxypropoxy)phenyl]propane),Bis-EMA(2,2bis[4-(2 methacryloxyethoxy) phenyl] pro-pane, TEGDMA (triethyleneglycol dimethacrylate),

and UDMA (urethane dimethylacrylate) (Sideridouet al., 2003; Floyd and Dickens, 2006).

In our study, at the end of 3 months, the binarypeaks in 3488, 3465 cm21’ is thought to belong to theamine group occurred by hydrolysis of urethane group.In the literature, it was reported that urethane aretransformed into the amine and alcohol on this pHrange by hydrolyzing (Floyd and Dickens, 2006). Thenbroad peak around 3180–3000 cm21 is thought to

Fig. 7. Spectrums of Primary tooth in (A) Buttermilk, (B) strawberry yoghurt, (C) Coca-Cola, and(D) orange juice at different times of 0, 3, and 6 months.

Fig. 8. Spectrum of permanent tooth in (A) Buttermilk, (B) strawberry yoghurt, (C) Coca-Cola, and(D) orange juice at different times of 0, 3, and 6 months.



belong to carboxylic acids, alcohols, and absorbedwater resulting from the hydrolysis of the ester groups(Norberto et al., 2007). Broad peak between 3500 and3100 cm21 occurred on the sixth months is thought tobe OAH peak belonging to water absorption. However,carboxylic acids and alcohols formed by the esterhydrolysis, as well as different alcohols formed as aresult of urethane hydrolysis are also observed in thissame absorption peak area. Mac Carty and Nobertoreported encountering peaks from the other groups in

the same area under a wide water band (Ferracane,2006; MacCarthy et al., 1975). Again the smallsignal coming from 3700 to 3600 area indicate thatthe presence of absorbed water (Cervantes-Uc et al.,2006).

On the third month, while peak amine at 1651 cm21

point NAH bending, at the end of sixth month thepeak at 1737 cm21 is thought to belong to carboxylicacids. The peaks at 1017, 1049, and 1027 cm21 islocated in the vibration of alcohols belonging to their

Fig. 9. Spectra of Filtek Z-250 in (A) Buttermilk, (B) strawberry yoghurt, (C) Coca-Cola, and(D) orange juice at different times of 0, 3, and 6 months.

Fig. 10. Spectrum of Dyract Extra in (A) Buttermilk, (B) strawberry yoghurt, (C) Coca-Cola, and(D) orange juice at different times of 0, 3, and 6 months.

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CAO bond. However, especially on the sixth monthsthe increase in the intensity of CAO band in 1027cm21 relatively may be caused by new alcoholsoccurred by hydrolysis in the acid environment (Mac-Carthy et al., 1975). Thermal degradation of thesepolymers was found in the new formation of alcohols(Finer and Santerre, 2006). The relative increase ofthe peak at 790 cm21 at a later time is speculated tobe a NAH wag peak belonging to amines formed byurethane hydrolysis (Zhang et al., 2000; Larkin,2011).

Essentially, the pH may have accomplished in theresin matrixes of the hybrid composites to form thecarboxylic acid alcohol and amine (from UDMA hydro-lysis) molecules through catalysis of esters groupsfrom dimethacrylate monomers present in their com-positions (Bis-GMA, Bis-EMA, UDMA, and TEGDMA)(Da Silva et al., 2010). The hydrolysis of these estergroups may have formed corresponding alcohols andmethacrylic acid (MA) molecules that may have accel-erated degradation of resin composites and promotesmonomers elution due to a lowering of the pH insidetheir matrixes (G€opferich, 1996). It is believed thatacids seem to have the influence on promoting therelease of unreacted monomers and inorganic fillers(Eisenburger et al., 2003). Carboxylic acid, alcohol,and amines occur as a result of hydrolysis of ester andurethane structures on Filtek Z-250 used in this study(Schollenberger and Stewart, 1971). Besides, in thethermal degradation studies performed by Jaffer andTeshima, it was reported that these products havebeen formed (Tuan Rahima et al., 2012; Moszner et al.,2005). In previous studies, degradation products ofBis-GMA and TEGDMA were established by HPLCand were pointed out same molecules bishydroxypro-poxyphenyl propane (Bis-HPPP), Bisphenol A (BPA),triethylene glycol (TEG), and MA and so forth (Finerand Santerre, 2006; Fleisch et al., 2010).

When the low pH decreases, water absorption mayincrease. Also the chemical structure of the resinmonomers is important for water sorption of polymercomposites. The hydrophilic monomers tend to beattracted by water molecules to form hydrogen bond-ing. Because of the hydroxyl group Bis-GMA wouldform a stronger hydrogen bonding with water mole-cules compared to ether (in Bis-EMA) and urethane (inUDMA) linkage. The hyrophilicity is lower in UDMAmonomer, it may limit the movement of water mole-cules between the polymer chains (Sideridou et al.,2003; Venz and Dickens, 1991). The hyrophilicity ofmonomers is to be in following order: TEGDMA>Bis-GMA>UDMA (Venz and Dickens, 1991).

Dyract Extra

In the polymer structure of Dyract Extra there areUDMA, TEGDMA, and Ethylene dimethacrylate(EDMA) as monomers and Butylated hydroxytoluene(BHT), Diester of 2-hydroxyethyl dimethacrylate withbutane tetracarboxylic acid (TCB) (Hedzelek et al.,2008). EDMA and TCB’s open structures and productsoccurred by the hydrolysis were shown in SupportingInformation Figure S2. (Van Landuyt, 2007). All ofthese formations of new peaks support fragmentationon the surface of the polymer proposed in Figure 10. Itcan be seen the SEM analysis in Figure 4.

Urethane and ester structures in Dyract Extra cancreate amine, carboxylic acid, and alcohol by hydrolyz-ing. It can be said binary amino peaks seen at 3489,3463 cm21 at the first 3 months point amines groupsresulting from hydrolysis of urethane. On the sixthmonth, however, broad OAH peak emerges due toabsorption of more water. Peaks belonging to carbox-ylic acid, alcohol, and amine group formed at the sameregion are also observed below the large water band.

In addition, according to the initial spectrum, thepeaks emerges at the third and sixth month on 1724–1651 cm21, the new carboxylic acids are believed tobelong to C@O groups and amine NAH bend respec-tively. Initially, the peak coming at 948 cm21, the OAHbending peak of carboxylic acid has shifted to 1051 (alco-hol CAO) cm21 at the third and sixth month. This is dueto diol structure formed by the hydrolysis of urethanesand of Hydroxylethylmethacrylate (HEMA) hydrolysis.Due to water-retaining HEMA separated from TCB, theintensity of the peaks belonging to water increased as itis seem in the spectra (Van Landuyt, 2007).

HEMA and butanetetracarboxylic acid with thehydrolysis of TCB; carboxylic acid, and ethylene glycolwith the hydrolysis HEMA occurs (Prakki et al., 2005).TCB structure provides both cross-connects and thewater retention (Daniel, 2009). Acidic solution mayprovide a sufficient concentration of protonated pro-tons to induce the hydrolysis of ester portion presentsin the resin matrix (Nishiyama et al., 2004). As aresult of hydrolysis of esters and urethanes in thestructure of polymeric UDMA, it can be said thatamine, alcohol, and carboxylic acids will occur. Hydro-lysis of TEGDMA and EDMA give MA and TEG (Finer,2000; Finer and Santerre, 2006).

Fuji II LC

The monomers in the polymeric structure of Fuji IILC are HEMA, dimethylacrylate, polyacrylic acid (PA),and fluoro alumino silicate glass as inorganic (Mauroet al., 2009). Of this methacrylate, PA’s open structureand fragmentation products were shown in SupportingInformation Figure S3 (Young et al., 2004). The newpeaks support the products in Figure 11. It can be seenthe SEM analysis in Figure 5.

For Fuji II LC the peak observed at 3600–3000 cm21

on the third and sixth month indicates the absorptionwater intensively (Pramoda et al., 2003). In the studiesalready done due to hydrophilic structure, it wasexpressed HEMA will cause to increase the waterabsorption (Sadr et al., 2007; Caykara et al., 2007).Therefore, as it is seen from the spectra, the intensityof peaks belonging to water has increased.

While the peak at t 5 0 1722cm21 is pointing theester carbonyl in the structure of HEMA, this peak isshifting to smaller wave numbers because of bothabsorbing water intensely at the third and sixthmonths, and the carboxylic acids. The peaks at 1560and 1456 states carboxylate anion (COO2) due to thepresence of water and the pH of medium. Conversionof one of the carboxyl groups of acrylic acid to carboxy-late anion in pH 2–6 is reported (Patel et al., 2003; Liuet al., 2007).

OAH bending band at the t 5 0 948 cm21 belongingto carboxylic acid does not appear at a later date. Wesuggest because the structure absorbs water the peak



fades and over time it disappears. Then, on the thirdand sixth month instead of the peak, respectively, thepeaks at 1082 and 1072 cm21 is considered to be CAOpeak belonging to alcohol composed by HEMA’shydrolysis.

Eisenburg et al. showed that the erosion depth ofGICs increased when the pH of acid solution wasdecreased. They proposed that H1 ion concentration inacid solution is the promotive in cement erosion. The

low pH as the inside coke and orange juice may catalyzethe hydrolysis of ester groups of dimethacrylate mono-mers in the resin matrix. So the carboxylic acid and alco-hol molecules forms (Larkin, 2011; Da Silva et al., 2010).

Fuji IX

It can be seen the spectrum in Figure 12 and theSEM analysis in Figure 6 for the Fuji IX. Fuji IX hasPA, itakonic acid (IA)-acrylic acid (AA), acrylic acid-

Fig. 12. Spectrum of Fuji IX’s in (A) Buttermilk, (B) strawberry yoghurt, (C) Coca-Cola, and (D) orangejuice at different times of 0, 3 and 6 months.

Fig. 11. Spectrum of Fuji II LC in (A) Buttermilk, (B) strawberry yoghurt, (C) Coca-Cola, and (D)orange juice at different times of 0, 3, and 6 months.

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maleic acid, and rich structure in fluor as inorganic.AA-IA, AA-MA products with their open structure andproducts were shown in Supporting Information Fig-ure S4 (Young et al., 2004).

When the spectra were analyzed for Fuji IX, at thethird and sixth month period, the broad-band observedat 3600 to 3000 cm21 was evaluated as OAH peak ofwater absorbed. Because the hydrophilic portions ofpolymeric structure is capable of handling a largeamount of water. Furthermore, interactions are pH-dependent because of the involvement of ionizablegroups (Park and Robinson, 1987).

Initially, the peaks at 1739, 1702, 1694, and 1648cm21 indicate carbonyl group of very different acidicmonomer. At different times of 0, 3, and 6 months thepeaks observed at 1632 and 1625 cm21 are indicatorsof carboxylate anion due to the presence of water andpH of medium. As well as PA, PA-IA and PA-MA rangeionized by losing one of protons from its carboxyl groupat this pH (Patel et al., 2003; Nicholson, 1998).

In previous study, GICs showed the highest micro-hardness losses, followed by resin composites. Sincesiliceous hydrogel layer could dissolve, the matrix dis-solution peripheral to glass particles could occur inGICs. Although this adverse result, the erosive loss ofGICs may be accompanied by increasing in the pH ofacid solution (Francisconi et al., 2008).

It seems the most alterations in orange juice. In ear-lier studies, it was showed greater surface hardnesslosses for apple and orange juice when compared tocolas. Since these juices contain carboxylic acids, theycan form complexes of solubility in water by generat-ing chelating ions. A coke contains phosphoric acid(PA), it does not chelate ions. Thus less damage istaken place in dental materials and tooth structure(Aliping-McKenzie et al., 2004).

CONCLUSIONS

This study was designed to test the null hypothesisthat acidic foods and beverages would reduce life timeof restorative materials by accelerating degradationand the human enamel would be more durable thanthem. Our results support this null hypothesis. Whenthe new peaks emerging in the spectra were inter-preted, it was understood that there are changes inchemical structure of all samples at the end of thethird and sixth months. However, the least affectedsamples of were both as primary teeth and permanentteeth. In particular, the samples held in coke andorange juice with low pH have peaks with the highestintensities. Besides, the wide-band at 3000–3600 cm21

of spectrums on the third and sixth months indicatesthe great water absorption in the samples because ofthe low pH of the most acidic drinks.

ACKNOWLEDGMENT

The authors declare that they have no conflict ofinterest.

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