Theobromine: A Safe and Effective Alternative for Fluoride in Dentifrices PDF

JOURNAL OF CAFFEINE RESEARCH Volume 6, Number 1, 2016 ª Mary Ann Liebert, Inc. DOI: 10.1089/jcr.2015.0023 Theobromine: A Safe and Effective Alternative for Fluoride in Dentifrices Tet...

JOURNAL OF CAFFEINE RESEARCH Volume 6, Number 1, 2016 ª Mary Ann Liebert, Inc. DOI: 10.1089/jcr.2015.0023 Theobromine: A Safe and Effective Alternative for Fluoride in Dentifrices Tetsuo Nakamoto, DDS, PhD,1 Alexander U. Falster, MS,2 and William B. Simmons, Jr., PhD2 During the process of studying caffeine’s effects on developing teeth, a serendipitous discovery was made. Teeth comprise hydroxylapatite (HAP). Ingestion of caffeine (1,3,7-trimethylxanthine) caused the forma- tion of smaller crystallites of HAP in the developing teeth. This resulted in the increased release of calcium and phosphorus ions from the enamel surface when exposed to acidic solutions in vitro. Furthermore, an- imal study confirmed the hypothesis that smaller HAP crystallites caused the increased incidence of dental caries. In contrast, theobromine (3,7-dimethylxanthine), which is similar to caffeine, caused formation of larger HAP crystallites in vitro. The ingestion of theobromine by lactating dams showed a decreased release of calcium and phosphorus ions from the enamel surface in the developing teeth of neonates in vivo. The use of fluoride dentifrices is controversial. It is also well documented that young children who brush their teeth often ingest fluoride-containing dentifrices. Based upon our comparative study between fluoride and theobromine, theobromine is a better alternative than fluoride. We believe that theobromine can be used as an ingredient of dentifrices and even if swallowed accidentally, there are no adverse effects. Introduction Caffeine (1,3,7-trimethylxanthine) and fluoride are common ingredients encountered in our daily lives. Caf- I n modern times, people started realizing gradually that what they eat or drink in daily life could be closely related to their health. Well-informed consumers care- feine is present in beverages, such as coffee, colas, some teas, and some over-the-counter medications.1 Fluoride is also contained in most dentifrices and in drinking fully look at the composition of their food and drink be- water in the some parts of the United States. fore they purchase them. Yet, at the same time, the Although caffeine can be commonly found in most inclusion of the word, natural, catches consumers’ eyes American lifestyles, caffeine’s effects on growing off- no matter what the product’s level of naturalness. spring during pregnancy and early postnatal period are Dietary ingredients may play an important role in con- still debated, even if one considers the amounts of caf- sumer health. In the laboratory setting, however, deter- feine as not excessive. The half-life of caffeine in neona- mining how these factors might be interrelated is a tes is much longer than in adults2; therefore, caffeine field still in the developmental stages. Because fetal stays longer in neonate bodies. Fluoride is known to mass increases hugely during pregnancy and from birth have adverse effects.3–5 to weaning, the nutritional stress, if any, will be most pro- The neonatal teeth of the suckling pups were affected nounced during early growth periods. However, because by protein-energy malnutrition and have shown greater each organ has a different critical period of growth, some calcium and phosphorus release from the enamel surface organs may be affected, whereas others might not, compared with the control group when exposed to an depending on whether nutritional stress is acting at that acid solution in vitro.6 Originally, this research led us to particular time of development. However, if affected, the study about the possible effects of caffeine-related nu- even if the diet is corrected later in life, this organ will tritional stress on the enamel surface of developing teeth. not recover from the early nutritional stress once the crit- The presence of caffeine in drinks and medications is ical growth period has passed. surrounding us in our daily life; caffeine’s possible 1 Department of Physiology, Louisiana State University Health Sciences Center, New Orleans, Louisiana. 2 Maine Mineral and Gem Museum, Bethel, Maine. 1 2 NAKAMOTO ET AL. effects on developing teeth have not been given adequate of the X-ray diffraction peaks compared with the noncaf- attention. Caffeine diffuses in breast milk in humans7 and feine control group.13 This explains that the smaller crystal- rats.8 The suckling pups took in caffeine through the milk lites with greater surface area were more easily dissolved when the maternal diet was supplemented with caffeine. when teeth were exposed to acid solutions in vitro. Thus, Thus, maternal caffeine supplementation in the diet dur- crystallites in acid-susceptible teeth are smaller than those ing the lactation period alters the composition of the de- in acid-resistant teeth.14 Therefore, it would be likely that veloping teeth of the suckling rat pups.9 The calcium those teeth exposed to caffeine in the early neonatal period content of the incisor and first molar in the caffeine- would easily dissolve and result in dental caries-prone teeth supplemented group of the normally nourished group in the future. was less than that in the noncaffeine group. We did not No such differences are found in the second molars be- know at that time whether this change of calcium content tween the caffeine group and the noncaffeine control of the whole teeth came from the enamel, dentine, or group within the same experimental conditions.11 The both. However, we knew that if the enamel surface of differing results can be explained by different critical pe- the teeth could be impaired by a decrease in calcium riods of growth of teeth, where the nutritional effects are resulting from maternal caffeine intake, these animals exerted at a particular time period of growth and devel- might develop caries-prone teeth. opment. That is, the first molar was influenced by the caf- feine exposure during its critical time period, whereas How Did the Caffeine Intake by Rat Dams Affect second molar was not. We did not determine the critical the Developing Teeth of Neonates? period of second molars. Study of early postnatal period Study of prenatal period In a series of experiments, caffeine was added to the To study the prenatal effects of caffeine on developing maternal diet (2 mg/100 g body weight of dam). The teeth, time-release 100 mg caffeine tablets were subcutane- equivalent comparison between caffeine in the rat diet ously implanted in rat dams at day 7 of gestation.15 The and a human diet is based on metabolic body weight tablet released caffeine into the body at an intake compara- (kg0.75) (Metabolic rates are expressed in terms of Kleib- ble with about one to one and one-half cups of coffee dur- er’s10 metabolic body size—i.e., kg0.75, the point at which ing pregnancy based upon the metabolic body weight the dependence on different body sizes disappears). The (kg0.75).10 At birth, pups were assigned to surrogate dams human caffeine intake is comparable with slightly more that were not exposed to caffeine during gestation. There- than two cups of coffee. At the end of weaning postnatal fore, we determined the caffeine’s effects on neonates dur- day 22 (birth day counted as day 1), first and second mo- ing only the gestational period. At postnatal day 22, the rat lars were removed. The third molar was in a jelly-like con- pups were killed and the first and second molars were dition (i.e., not fully developed), so we did not study it at extracted. that time. The studies were conducted in a similar way as Using the same in vitro study method,11 we measured the described previously.6 The calcium, phosphorus, and release of calcium, phosphorus, and magnesium. Signifi- magnesium amounts released from the enamel surface cantly, more calcium and phosphorus were released from of the first molars over 80 minutes of in vitro study the enamel surface of the first molar in the caffeine group were significantly higher compared with the noncaffeine compared with the noncaffeine control, but magnesium control group.11 We did not know why these ions were re- showed no difference between the groups in the first leased from the enamel surface of the first molars. molar. We found no significant differences in the second Because teeth comprise hydroxylapatite (HAP), appar- molar. Possible explanations for the different data regarding ently some physical change might have occurred in the the observed effects of caffeine exposure on developing HAP of the enamel surface of the first molars as a result teeth between the prenatal study15 and the postnatal of the exposure to caffeine. A collaboration with Drs. study11 include the slightly smaller caffeine exposure in Falster and Simmons at the University of New Orleans, the prenatal research compared with the postnatal study11 Department of Geology and Geophysics—who were ex- and differences in the critical developmental period of the perts on HAP—was begun to determine the cause and ef- first molars. HAP formation between prenatal15 and postna- fects behind these data. tal study11 might have been slightly different, although both According to the suggestions, the extracted teeth were enamel surfaces showed smaller crystallites in the caffeine pulverized and the sample powder was separated into group compared with the noncaffeine control.11,15 enamel and dentine.12 Several pure enamel samples of the untreated control and caffeine groups were run for 4 hours on a 114 mm Gandolfi X-ray powder camera.13 Postnatal caffeine exposure and the incidence of dental caries The data showed that caffeine supplementation in the ma- ternal diet affected the mineralization of enamel and re- Subsequently, we hypothesized that caffeine-exposed sults in smaller crystallites, indicated by peak broadening teeth will develop dental caries more readily than teeth THEOBROMINE AS AN ALTERNATIVE FOR FLUORIDE 3 of noncaffeine controls. To test this hypothesis, we raised Table 1. Hydroxylapatite Formed In Vitro rat pups in the same way as described,11 and then fed in the Presence of Various Xanthines them a cariogenic diet from weaning on postnatal day Amount of 22 to postnatal day 50.16 At day 50, the first molars additive in mg/L solution FWHM/M were examined by the established method of caries score.17 The results clearly demonstrated that caffeine Control 0 0.75 exposure during the neonatal period resulted in signifi- Caffeine 200 1.00 Caffeine 50 0.90 cantly higher caries scores compared with the noncaf- Uric acid 200 0.96 feine control group.16 Uric acid 50 0.90 These experiments suggest that even a relatively small Theobromine 200 0.15 amount of caffeine exposure during the early postnatal Theobromine 50 0.19 period and/or pregnancy will influence developing teeth Theophylline 200 0.40 Theophylline 50 0.50 and result in teeth prone to developing dental caries 1-Methylxanthine 200 0.60 later in life. 1-Methylxanthine 50 0.68 3-Methylxanthine 200 0.21 3-Methylxanthine 50 0.39 How Theobromine’s Effect Was Discovered 7-Methylxanthine 200 0.45 7-Methylxanthine 50 0.68 In vitro crystal formation study. Because our series of in vivo caffeine experiments took more than several years The results in terms of FWHM (full-width–half-maximum peak height) divided by M (maximum peak height) (FWHM/ to complete, we decided to conduct simple in vitro experi- M) and for the (300) reflection are given for the control and ments to form HAP crystallites in the presence of other the xanthine compounds. xanthine compounds to determine what effects the com- pounds might have on HAP formation, relative to caffeine. In vitro experiments involved growing apatite from di- X-ray diffraction scans of the (300) reflection of apa- lute solutions of CaCl2 and Na3 PO4.18,19 All solutions tite grown in vitro in the presence of 200 mg/L theobro- contained 0.01 M CaCl2 and Na3 PO4. Several sets of ex- mine produced sharper (300) peaks with less peak periments added each of the methylxanthines or uric acid broadening, and secondary electron images of apatite in two concentrations, 50 mg/L and 200 mg/L. The effect grown in vitro in the presence of 200 mg/L theobromine of the xanthine compounds was compared with a control were measured to be more than 2 lm.18,19 solution containing CaCl2 and Na3 PO4 only. Theobromine increased the crystallites approximately Solutions were mixed at 25C and the pH adjusted to four times compared with the control group (without ad- 9–9.5 with 0.1 M NaOH and the solutions were left to ditives) in the in vitro study. crystallize for 20 days. The crystalline precipitate was These unexpected findings about the increased crystal- washed five times with distilled water and prepared for linity of theobromine were surprising. Why would X-ray diffraction, which was performed on a SCINTAG caffeine (1,3,7-trimethylxanthine) and theobromine (3,7- XDS 2000 X-ray diffractometer. The (300) reflection dimethyxanthine), which are chemically very similar, was scanned to investigate crystallinity. The results of cause crystallite formation that was entirely opposite: caf- this study are given in Table 1. feine produced small crystallites, and theobromine pro- The experiments that used theobromine or 3- duced large crystallites. methylxanthine show the most pronounced increases in Postnatal study of developing teeth by theobromine crystallinity compared with the control group. This result is evident from lower values of the ratios FWHM (full- Based on the in vitro study, we decided to conduct an width–half-maximum peak height) divided by M (maxi- in vivo study with the following hypothesis. If we con- mum peak height) (FWHM/M) compared with the control. ducted the same experiment on developing teeth as we Lower ratio values indicate better crystallinity. All of the had with the caffeine study,11 but supplemented theobro- methylated xanthines, except caffeine, increased the crys- mine in the maternal diet instead of caffeine, we believed tallinity of the precipitating apatite. In every case, the crys- that the first molars of the suckling pups whose milk con- tallinity increased with xanthine concentration. Caffeine tained theobromine should release fewer minerals from and uric acid decreased the crystallinity of the apatite the enamel surface compared with the first molars of also in a dose-dependent manner.18,19 We did not expect the nontheobromine-supplemented group. In the supple- these results. mented group, the first molars would be formed with big- Peak broadening of crystallites in vitro was measured ger HAP crystallites on the enamel surface. The bigger by X-ray diffraction scans of the (300) reflection of apa- HAP crystallites were more acid resistant.14 tite grown in vitro without additives (control) and sec- The theobromine supplementation of the maternal diet ondary electron images of apatite grown in vitro was 1 mg/100 g of the dam’s weight. Assuming that the without additives (control) measured to be 0.5 lm.18,19 theobromine content of a 1 oz. bar of milk chocolate is 4 NAKAMOTO ET AL. 45–105 mg,20 and that the conversion is based on the the chemical composition of the theobromine versus caf- metabolic body weight (kg0.75),10 the dosage (1 mg/ feine groups. 100 g body weight) in rats is equivalent to 129 mg/65 (kg0.75). This corresponds approximately to slightly Does Chocolate Prevent Dental Caries? more than one to three bars of 1 oz. milk chocolate for First evidence of chocolate and dental caries in humans a 65 kg human. During the lactating period, suckling rat pups received theobromine through the maternal Cocoa is a major source of theobromine, and cocoa per milk because theobromine diffuses into milk just as caf- se has no reported adverse effects that would be injurious feine does.2 to man.2 Because chocolate contains theobromine, it is On postnatal day 22, first molars from the mandible and interesting to see how the past history reveals the study maxilla of randomly selected pups were removed. These relationship between chocolate and dental health. In the first molars were mounted with a sticky wax on a small middle of the 1950s, milk chocolate was provided as plastic block to study the acid solubility of the enamel sur- part of caries research on patients at the Vipeholm Men- face as was performed previously in the caffeine study.11 tal Hospital (Sweden).21 The increase in caries activity The data showed that significantly less calcium, phospho- during the chocolate-ingestion period was less than rus, and magnesium from the enamel surface were released expected from the amount of sugar consumed and the from the theobromine-supplemented group compared with sugar clearance time in saliva. These results led to the hy- the nonsupplemented group.18,19 Thus, our hypothesis pothesis that some kind of caries-inhibiting constituent in proved correct as bigger crystalline HAP is more resistant chocolate might exist.21 to acid dissolution.14 Stralfors’ study series on cocoa and dental caries How the crystal structure between control About 50 years ago, using hamsters, Stralfors con- and theobromine differs ducted a series of experiments on the relationship between It has been reported that the calcium and phosphorus cocoa powder and the inhibition of dental caries.22 This re- contents of acid-resistant teeth were at least 20% higher search was based upon the study by Gustafson et al.,21 than that of the acid-susceptible teeth.14 Therefore, we fur- showing that the introduction of milk chocolate led to ther studied how the composition of the increased HAP of less caries activity. Whole cocoa powder inhibited caries the enamel—which was bigger in the theobromine- by 84%, 75%, 60%, and 42%, when the cocoa content supplemented group—differs from the nontheobromine of the diet was 20%, 10%, 5%, and 2%, respectively. control group. However, cocoa butter incorporated into a diet in an Calcium and phosphorus concentrations were deter- amount of 15% increased dental caries considerably.22 mined in the enamel of first molars extracted from Based upon this initial research,22 Stralfors concluded theobromine-exposed rats and control rats by electron that the cariostatic factors are located in the nonfat part microprobe analysis using an ARL-SEMQ electron of cocoa. There seem to exist at least two cariostatic fac- microprobe. Fluorapatite from Cerro de Mercado tors, one insoluble in water at ordinary temperature and (Mexico) was used as a standard. The results obtained another soluble in water.23 In the following studies, Stral- are shown in Table 2. fors speculated that the tannin in cocoa could be a caries- From the data, there is no significant difference in the inhibitive constituent and that other caries-inhibitive con- CaO and P2O5 between the two groups. Thus, the previ- stituents may be present.24 ously described results of acid dissolution are related to He further studied the purine derivatives, theobro- the crystallite size differences, not to a difference in mine, caffeine, and xanthine; the phenolic aldehyde van- illin and the tannin-containing material tannic acid— which is a hydrolysable tannin—and mimosa and que- Table 2. Calcium and Phosphorus Concentration bracho extracts.25 Some of the materials inhibited dental Determined by Electron Microprobe Analyses caries, depending upon the concentration added to the Sample No. P2O5 weight percent CaO weight percent diet. When a large amount of the above materials was added, the growth of the animal was inhibited. Control group Both theobromine and caffeine significantly inhibited 28 38.11 53.24 30 36.68 53.60 dental caries when a higher caffeine concentration was 10 36.55 52.20 added, but when the concentration of caffeine was less, Average 37.11 53.01 dental caries was not inhibited.25 This result is in contrast Theobromine group to our findings in the crystallization study of caffeine.16 29 34.55 52.70 In a separate study, Stralfors fed milk chocolate to one 24 37.63 53.17 group and dark chocolate to another group. To his sur- 37 38.53 51.79 prise, he found that there was a reduction of caries by Average 36.90 52.55 35% for milk chocolate and 73% for dark chocolate.26 THEOBROMINE AS AN ALTERNATIVE FOR FLUORIDE 5 An earlier article22 had shown that caries inhibition was caused by fat-free cocoa. Therefore, he explained, the dif- ferent cocoa content of the two chocolate types (milk chocolate vs. dark chocolate) was likely the main reason for their differing ability to counteract dental caries. From our studies, the above phenomena can be easily explained.26 Chocolate liquor is the base substance from which all chocolate products are produced. Cocoa is pre- pared by pulverizing the material remaining after the fat (cocoa butter) is removed from chocolate liquor.20 The average percent of theobromine in commercial cocoa is 1.89%, whereas that in commercial milk chocolates is 0.15%.20 Dark chocolate contains *12 times more theo- bromine than milk chocolates. Ooshima et al.27 observed that cacao mass extract pos- sesses some anticariogenic potential, but concluded that FIG. 1. Changes of hardness of the enamel surface of its anticaries activity is not strong enough to significantly human teeth by different concentrations of theobromine suppress the cariogenic activity of sucrose. On the other and fluoride. hand, Ito et al.28 reported that the addition of a water- soluble extract of cacao powder significantly reduced caries scores in specific pathogen-free rats infected posed to acid solution in in vitro studies.14 Therefore, with Streptococcus sobrinus 6715. the teeth will become resistant to dental caries. In vitro pH cycling study between theobromine and fluoride Our study finally provided an answer for this old mystery To prove the points, the following in vitro study was From the above examples, one can see the speculation conducted. Using human teeth, the study investigated that chocolate has some basis to prevent dental caries. the remineralization potential of theobromine in compar- However, it was not known until now how and what chem- ison with a standard NaF dentifrice.32 Using an estab- ical material(s) might have played the critical role in the lished in vitro caries pH cycling (demineralization/ prevention of dental caries. Our accidental findings— remineralization) model, it was concluded that theobro- during the study of caffeine crystallization—that theobro- mine in an apatite-forming medium can enhance the mine increases the crystal size of HAP provided the clear remineralization potential of the medium. Therefore, answer for the mysterious phenomena of caries reduction theobromine could be a viable alternative to fluoride ad- related to chocolate consumption. ditives in commercial dentifrices. In this model, theobromine—at a molar level 71 times Theobromine’s Effects on the Teeth less than that of fluoride—has a remineralization effect Microhardness study by theobromine and fluoride on enamel lesions comparable with that of fluoride.32 on human teeth Evidence from the human study,21 the animal data previ- ously described,22–26 and a recent in vitro study,32 all Mineral changes in superficial enamel layers are di- point to the possible role of chocolate (via the theo- rectly related to the alternation of microhardness. If remi- bromine it contains) in the prevention of dental caries. neralization occurs, then the increased enamel surface is However, further human clinical studies are needed to associated with increased microhardness.29 The micro- exploit the benefit of theobromine on dental caries pre- hardness test using the different concentrations of theo- vention. bromine on the enamel surface was studied in human teeth as a pilot project. Surface microhardness values Repair of the enamel surface by theobromine showed that 200 mg/L theobromine protected enamel specimens more than 100 mg/L theobromine did. It was Figure 2A shows the enamel surface, which was concluded that consistent protection of enamel surface scratched using a sharp instrument. Figure 2B shows was observed in the theobromine group.30 the result after theobromine solution was applied to the We also have conducted detailed microhardness testing enamel surface. The teeth were bathed in enough solution using human teeth (Fig. 1).31 As can be seen, the horizon- to cover them for a duration of 30 minutes. The enamel tal line is the logarithm, which indicates that less theobro- surface repaired smoothly. mine was required to produce a much harder enamel The application of theobromine on the enamel sur- surface compared with the amount of fluoride. When the face produced a very smooth surface by the process of surface is harder, it is resistant to dissolution when ex- remineralization. 6 NAKAMOTO ET AL. FIG. 2. The scratched enamel surface before (A) and after the theobromine solution was applied (B). Hypersensitivity study of enamel surface of human teeth Erosion of tooth surfaces can result from consumption of many kinds of soft drinks, fruit juices, and wine. Hyper- sensitivity from this source is one of the problems often encountered by practicing dentists. It has been estimated that 15–57% of adults suffer from hypersensitivity,33 and the incidence appears to be increasing.34 An 80-person clinical study was conducted recently to determine whether theobromine can alter the hypersensi- tivity of teeth.35 The secondary electron microscope im- FIG. 3. Tooth surface before brushing (A). Surface ages show the results (Fig. 3). after brushing the tooth with fluoride-containing tooth- Figure 3A shows an eroded tooth surface before brush- paste for 1 week (B). Surface after brushing the tooth ing. Note the small dentinal tube openings exposed in the with theobromine-containing toothpaste for 1 week (C). mouth. The more the open tubes are exposed into the oral cavity, the more one will feel pain with cold or hot drinks. One of the treatments for sensitivity is to occlude most remain open, indicating that the toothpaste is not (close) these tubes.35 effective in reducing sensitivity. Results after brushing for 1 week with a regular, com- Figure 3C shows the results after using toothpaste mercially available fluoride-containing toothpaste (twice containing theobromine. Here, all tubes are fully oc- a day, morning and evening) are shown in the middle of cluded. The detailed study is presented in the original Figure 3B. Very little occlusion of the tubes is seen, and article.35 THEOBROMINE AS AN ALTERNATIVE FOR FLUORIDE 7 Dentifrices Containing Fluoride Are Associated brushes.45 It is difficult to train a 2 year old to spit out with Some Reported Problems toothpaste, particularly if it tastes great.40 Fluoride-based toothpastes have been the standard for A recent report from China demonstrated an associa- many years. In the presence of fluoride, fluoro-HAP crys- tion between fluoride intake and significantly lower IQ tals are formed. Partially fluoridated crystallites have scores for children.4 On the other hand, a more recent re- lower solubility in the acid produced by mouth bacteria port disputes the finding of a relationship between fluo- more than nonfluoridated HAP and thus protect against ride exposure and IQ.46 A review by Grandjean and tooth decay. Another role of fluoride is to stimulate remi- Landrigan47 suggested that further in-depth studies ex- neralization of teeth at the early stages of decay.36 The amine this aspect of fluoride. first fluoridated toothpastes were introduced in 1955.3 It appears that fluoride readily accumulates in the human pineal gland, and a positive correlation between Note warning with each toothpaste fluoride and calcium content in this gland has been shown.38 The pineal gland produces melatonin, a hor- Although fluoride has been considered the gold stan- mone related to setting the rhythms and duration of dard in oral care, each toothpaste containing fluoride sleep. The degree of calcification has been associated bears the warning ‘‘Keep out of reach of children under with a decreased secretion of melatonin.48 Thus, exces- 6 years of age. If more than used for brushing is acciden- sive fluoride use could result in the disturbance of circa- tally swallowed, get medical help or contact a Poison dian rhythms and sleep patterns.49 Control Center right away.’’ In 1994, the American A possible relationship between fluoride intake and Association of Poison Control Centers recorded 3095 thyroid gland disease has been reported.50 There are calls about suspected overingestion of fluoridated tooth- many pro and con arguments as to fluoride’s cavity- paste.37 A report from Poison Control Centers showed fighting benefits. In light of the evidence presented 21,513 calls in 2011 concerning fluoridated toothpaste above concerning possible adverse effects, it is under- ingestion.38 standable that some opposition has developed against In view of this warning, one wonders what adverse ac- daily fluoride use in dentifrices. cumulative effects there may be on the general health of children in their later lives, particularly if they are over- exposed to fluoride during an early critical growing pe- Where Are We Going from Here riod. In addition, what effects might we see in adult Since Colorado dentist Dr. Mckay’s findings in the and elderly populations who may be exposed daily to, early 20th century led to the discovery of fluoride’s effect or periodically swallow, small amounts of fluoride on teeth,3 fluoride became the most common ingredient throughout their lives? in dentifrice and remains so at the present time. Never- theless, some adverse effects of fluoride have been Possible adverse effects of fluoride reported in the present and past. Ingestion of excess fluoride is known to be associated In a Mayan skull—reported to be *1100 years old— with an increased risk of permanent discoloration in de- three round jade inlays are clearly embedded in the front veloping teeth. More than 90% of toothpaste in the teeth.51 In the ancient time in the Mayan culture, cocoa United States is fluoridated, and many children are ex- was used only among the wealthy. What is surprising posed to fluoride through incidental ingestion of tooth- about the skull is that to embed a jade inlay into each paste.39 Toothpastes specifically flavored for children tooth, they had to drill the enamel surface of the tooth. have been linked to the use of larger quantities of tooth- However, drilling the precise hole to embed the jade paste than suggested, increasing the importance of the would have been difficult if not impossible. It seems pathway of excessive fluoride intake.40 that somehow after placing the jade into each tooth, An increased risk of skeletal fluorosis due to exces- they must have had the knowledge to fix the jade within sive fluoride is reported.41 Fluoride is also a risk factor the hole. We speculate that cocoa extract—with the theo- for osteosarcoma among boys.42 However, Douglass bromine discussed in this article—extracted from cocoa and Joshipura43 warned about the incidence of osteosar- powder was applied to fill the marginal space around coma, which may require a different interpretation of the jade and initiate mineralization. Thus, the jade their finding, because unpublished data contradict the could be fixed into the enamel surface. This speculation risk of osteosarcoma.3 stems from our current study, which is shown in Figure 2, Dentists in the United States are seeing young children where the impaired tooth surface was filled by HAP with with as many as 10 cavities. The American Dental Asso- the help of theobromine. Somehow these Mayan elites ciation recommends using only a pea-sized amount of knew the role of cocoa extract in dental applications fluoride toothpaste for brushing, beginning at 2 years of more than 1100 years ago. age.44 Unfortunately, children between the ages of 1 As Mayan culture already, 1100 years ago, knew and 3 years ingest 30–75% of the toothpaste on their cocoa’s unique role, it is interesting to imagine that 8 NAKAMOTO ET AL. Natives living in the deep Amazon, for example, may 5. Luke J. Fluoride deposition in the aged human pineal have unique remedies learned from their ancestors. gland. Caries Res. 2001;35:125–128. These remedies may be more effective than that created 6. Aponte-Merced L, Navia JM. Pre-eruptive protein- energy malnutrition and acid solubility of rat molar by modern science. enamel surfaces. Arch Oral Biol. 1980;25:701–705. Although dental caries is prevalent within our society, 7. Aldridge A, Aranda JV, Neims AM. Caffeine metabo- the role of theobromine to prevent the dental caries in the lism in the newborn. Clin Pharmacol Ther. 1975;25: clinical study has yet to be investigated and definitely 977–981. proven. However, we have every reason to believe that 8. Aeschbacher HU, Milton H, Pott A, Wurzner HP. Effect theobromine is 21st century’s most important ingredient of caffeine on rat offspring from treated dams. Toxicol in future dentifrices in our society. Cocoa has been used Lett. 1980;7:71–77. 9. Nakamoto T, Shaye R, Mallek HM. Effects of maternal for centuries without any ill effects. Our data have con- caffeine intake on the growth of tooth germs in protein- vinced us that if fluoride is 20th century’s discovery to energy malnourished neonates. Arch Oral Biol. 1985; prevent dental caries, theobromine will play a similar 30:105–109. role in the 21st century. Theobromine is superior to 10. Kleiber M. Body size and metabolic rate. In: The Fire of and a safer material than fluoride. Life, an Introduction to Animal Energetics. New York: Wiley; 1961: pp. 177–216. 11. Hashimoto K, Joseph F Jr, Falster AU, Simmons WB, Acknowledgments Nakamoto T. Effects of maternal caffeine intake during Just 10 years ago, August, 2005, Hurricane Katrina lactational period on molar enamel surfaces in newborn rats. Arch Oral Biol. 1992;37:105–109. devastated New Orleans. Many people left New Orleans, in- 12. Manly RS, Hodge HC. Density and refractive index cluding the mentor of graduate student, Arman Sadeghpour, studies of dental hard tissue—I. Method for separation who was planning to study PhD dissertation, although I, and determination of purity. J Dent Res. 1939;18: Tetsuo Nakamoto, knew him as a high school student. As 133–141. a result of Hurricane Katrina, I became his mentor for his 13. Falster AU, Hashimoto K, Nakamoto T, Simmons WB. dissertation. He is a meticulous researcher. Once the com- Physical examination of caffeine’s effects on the enamel parative study between theobromine and fluoride on hard- surface of first molars in newborn rats. Arch Oral Biol. 1992;37:111–118. ness using human teeth on his dissertation was done, it 14. Besic FC, Bayard M, Weimann MR Jr, Burrell KH. became very clear that theobromine is superb in every pa- Comparison and structure of dental enamel: elemental rameter he studied. Around that time, the authors met Mr. composition and crystalline structure of dental enamel Joseph Fuselier who was organizing a biotechnology group as they relate to its solubility. J Am Dent Assoc. interested in the New Orleans area after the devastation by 1975;91:594–601. Hurricane Katrina to revitalize the city. He has a great deal 15. Falster AU, Yoshino S, Hashimoto K, Joseph F Jr, Sim- of experience in the industrial aspects of biotechnology. mons WB, Nakamoto T. The effect of prenatal caffeine exposure on the enamel surface of the first molars of Not long after, Mr. R. Jantzen Hubbard joined the group newborn rats. Arch Oral Biol. 1993;38:441–447. and became a critical part of the operation the authors 16. Nakamoto T, Cheuk SL, Yoshino S, Falster AU, Sim- started. The authors would like to acknowledge each of mons WB. Cariogenic effect of caffeine intake during these individuals for their selfless participation in this ven- lactation on first molars of newborn rats. Arch Oral ture and dream. Finally, the authors appreciate Ms. Julie Biol. 1993;38:919–922. Schiavo, librarian at LSU Health Sciences Center, for her 17. Keyes PH. Dental caries in the molar teeth of rats. II. A help on various references for the review. method for diagnosis and scoring several types of lesions simultaneously. J Dent Res. 1958;37:1088–1099. 18. Nakamoto T, Simmons WB Jr, Falster AU. Products of Author Disclosure Statement apatite-forming-systems. 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Bronstein AC, Spyker DA, Cantilena LR, Rumack B, Department of Physiology Dart RC. 2011 Annual report of the American Associa- Louisiana State University Health Sciences Center tion of Poison Control Centers’ National Poison Data New Orleans, LA 70112 System (NPDS): 29th annual report. Clin Toxicol. 2012; 50:911–1164. E-mail: [email protected]