The Impact of Fruit Juice on Human Teeth - Research Paper Example

The Impact of Fruit Juice on Human Teeth Abstract Dental erosion or enamel erosion is a common health problem. Several studies have been conducted to evaluate the cause, progression, detection and management of dental erosion. The changing lifestyle pattern of human beings which incorporates consumption of acidic substances like soft drinks and fruit juices has been a major contributor for the development and progression of dental erosion. Immense research in this filed has strongly suggested a definite role in the consumption of fruit juices and soft drinks in the development of erosion of enamel. This literature review explores the impact of fruit juices on dental health. It also explored various investigations which are helpful in the detection and prediction of dental erosion. 1. Introduction The soaring rates of dental erosion even in children has led to enormous research in this field and the most commonly incriminated factor, according to several studies appears to the wide range of soft drinks, fruit juices and commercial juices availble in the market. 1.1Background information There is a rise in the incidence and prevalence of dental decay all over the world. This rise has been attributed to dramatic increase in the consumption of commercial fruit juices and soft drinks. Infact, several studies have been done to determine and ascertain the effect of intrinsic and extrinsic factors on the development of dental erosion ((Jensdottir et al, 2004). The factor which has been given utmost importance and is preventable is consumption of acidic drinks like soft drinks and fruit juices. Of interest are the natural and commercial fruit juices which are detrimental to dental health not only because of the sugar they have in them , but also because of the organic acids they are loaded with. Infact, an awareness of the link to juices to dental erosion have led to the development of several preventive strategies like dilution of juices and addition of calcium and fluoride to the juices. Increasing awareness of dental erosion has led to tremendous research and development in the investigation technology. Since erosion begins at nano-level, technology which can detect enamel erosion even at such small levels helps in detection and implementation of preventive strategies in an early stage. This review explores the impact of fruit juices on human teeth and the role of various investigations in the detection of the disease. 2. Literature Review 2.1. Human teeth Teeth are calcified and small whitish colored structures present in the jaws of vertebrates for the purpose of breakdown of ingested food.. They are the most distinctive features of mammals. While the most useful role of teeth is mastication, some vertebrates, especially the carnivores use teeth for defense and hunting food. The shape and size of the teeth depends on the food eaten and the uses they are put into. Human teeth have molars, canines and incisors (Johnson, 1998). Human teeth occupy about 20 percent of the surface area of the mouth. They are embedded through the gums into the maxillary and mandibular bones. The portion of the tooth which is seen is known as crown. It is covered with enamel and lies above the cementoenamel junction. Crown is made up of dentin and has a pulp chamber in the center. prior to eruption, the crown lies within the bone. The anatomic root of the tooth is covered with cementum and lies below the cementoenamel junction. The root is also made up of dentin and has pulp. A tooth may have one, two or three roots. Canines and premolars (except the upper first molars) have single roots. The upper first premolars and molars in the mandible have two roots and molars in the maxilla have 3 roots. Rarely more than 3 roots may be present and they are known as supernumerary roots (Johnson, 1998). Human beings have 2 sets of teeth, the primary teeth and the permanent teeth. The primary teeth are also known as the milk teeth or deciduous teeth. They are 20 in number, with 10 in the maxilla and 10 in the mandible. Primary teeth are weaker, smaller, whiter and softer than permanent teeth. Permanent teeth are 32 in number. The primary teeth will have central and lateral incisors and first and second molars. Except for the molars, all deciduous teeth will be replaced by permanent counterparts. The molars get replaced by premolars. The permanent teeth are 32 in number, which get divided equally between maxilla and mandible (Johnson, 1998). Figure.1: Human teeth alignment (Googleimages). 2.2. Structure of tooth. Teeth is made up of mainly four tissues and they are enamel, dentin, pulp and cementum (Johnson, 1998). Figure-2: Types of dental tissue (googleimages). Enamel Enamel is a mineralised substance and is the hardest substance in the body. It is visible. It is supported by dentin which underlies enamel. Enamel is semi-transluscent and thus the color of dentin influences its appearance. It is thickest near the cusp region, where the thickness is about 2.5mm and is thinnest towards border. Enamel does not contain any collagen. The proteins present in it are enamelins and amelogenins. These proteins serve as framework (Johnson, 1998). Dentin The material present beneath the enamel between the pulp and enamel or the enamel and pulp is known as dentin. Dentin is less mineralised and less brittle than the enamel and mainly acts to support the enamel. Dentin also supports the crown. However, it is softer when compared to enamel and thus decays rapidly leading to cavities. Even though the main composition of dentin is minerals, it has more organic tissue, most of which is collagen. It is made up of microscopic channels known as the dentinal tubules which start from the pulp and radiate outward towards the cementum. The tubules are widest near the pulp, the diameter being 2.5 micrometer near the region of the pulp and just 0.9nanometer at the dentino-enamel junction (Friedman, 1997). Cementum Cementum is the substance that covers the root. It is made up of inorganic material and lso organic material and water. The inorganic material constitutes about 45 percent of the substance and most of it is hydroxypatite. Collagen is the main constituent of organic substance. Cementum serves as a medium for the attachment of periodontal ligaments, thus playing an important role in tooth stability. Cementum is acellular in the upper 2/3rd region and cemento-enamel junction and cellular below it. It is yellowish and softer than enamel or dentin (Johnson, 1998). Pulp The central portion of the tooth that is filled with soft connective tissue is known as dental pulp. Nerves and blood vessels concerned to the tooth lie in this region. They enter the pulp through a hole in the root's apex region. The pulp is highly cellular and contains odontoblasts, preodontoblasts, fibroblasts, T lymphocytes and macrophages. Pulp is a very sensitive area (Johnson, 1998) 2.3. Properties of human tooth Human teeth are made up of both organic and inorganic composites in suh a way that their strength is enviable and they are resistant to damages. The enamel of human teeth is largely made up of calcium apatite which comprises 96 percent of enamel (Johnson, 1998). The apatite is either fluoroapatite or hydroxyapatite, because of which, teeth are very hard, infact, are the hardest and strongest biological material in the body of a human being. Thus, the ions which are found in the structure of enamel are fluoride, carbonate, magnesium and sodium. The rest of the enamel is made up of water (3 percent) and organic matter (one percent) (Johnson, 1998). Crystallites of hydroxyapatite are present in the form of nanorods. They are about 1mm long and their dimensions in cross section are approximately 50nm*25nm. These nanorods are present in the form of clusters of about 1000 crystallites which are known as prisms. The clusters may be as long as several millimeters and they are about 5 micrometer in diameter. Most of them are arranged in such a way that they are at 90 degrees to the enamel-dentine junction. Scanning electron microscopy has been an useful tool to study the orientation of prisms in an enamel and X-ray diffraction studies are useful to to establish the space and parameters of the crystals lattice. According to some studies, the space group is P63/m (hexagonal) and the lattice parameters are a=9.441(2) Å and c=6.878(1) Å (Low et al, 2009). The crystallite alignment is of a higher degree near the surface enamel when compared to enamel closer to the enemel-dentin junction (Low et al, 2009). The mineral particles of dentin and enamel lie embedded in the matrix of collagen. The mechanical properties of the enamel and dentin depend on the arrangement of the various crystals of the minerals within fibrils and their geometry and size. properties such as strength, hardness, toughness and stiffness are crucial for the support and function of the teeth and are mainly delivered by the mineral composition and not by the protein part, because protein is soft and weak and does not have the capacity to bear external load. However, the protein matrix has different roles like preventing the teeth from becoming brittle, offering protection to the mineral platelets and homogenisation of stress distribution. Research has shown that here is anisometry in the arrangement of crystal platelets in the dentin and enamel, similar to that in bone (Low et al, 2009). 2.4. Dental erosion Gradual erosion of the tooth is known as dental erosion. Dental erosion may be defined as "an acid induced loss of dental hard tissue that does not involve bacteria, and is therefore, not associated with dental plaque" (Jensdottir et al, 2004). Clinical features of dental erosion include increased transluscency at incisors, broad cavities with the enamel which has smooth surface, appearance of wear on surfaces which are non-occlusal, presence of amalgam which is clean and non-tarnished, raised restorations of amalgam, loss of typical surface characteristics of the enamel, hypersensitivity, exposure of the pulp in deciduous teeth and preservation of the "cuff” in gingival crevice regions (Deshpande and Hugar, 2004). Figure-3: Dental erosion (Googleimages) 2.5. Factors which affect erosion There are several factors which cause erosion of human dental enamel. Soft drinks and commercial fruit juices are major factors leading to dental erosion. In their study, Jensdottir et al (2004) found that there was a strong relation between dental erosion and consumption of soft drinks. According to a twenty year longitudinal study, drinking soft drinks between meals contributes to dental erosion (Low, Alhuthali, and Duraman, 2009). Acidic soft drinks are associated with dental decay. Lemonade is the most lethal for tooth. other soft drinks which contribute to dental erosion are sports drinks, energy drinks, iced tea, supplemented water and cola. Studies have shown that of all the soft drinks, the worst is cranberry juice (Low et al, 2009). Other than these factors, dietary acids, environmental acids and chemicals and gastric juices also contribute to dental erosion. These acids, cause dissolution and erosion of enamel (Amaechi and Higham, 2005). Dental erosion ultimately leads to irreversible loss of dental tissue by chemical mechanisms (Amaechi & Higham, 2005). The extent and degree of erosion of the enamel depends on several factors like the erosive medium, method of contact with teeth, frequency of contact, presence or absence of natural protective mechanisms like salivary fluid, dental anatomy and dental physiology. Increase in the frequency and duration of exposure to acidic medium increases the risk and severity of erosion. Calcium ions dissolve in acidic medium and cause weight loss of the mineral portion of the enamel. Consumption of soft drinks between meals causes more erosion than consumption with meals. The main reason for this difference is that consumption of soft drinks during meals is diluted by saliva and mastication and the soft drinks do not stick to the teeth directly, thus preventing chances of erosion. The more acidic the medium, the more the chances and degree of enamel erosion (Low et al, 2009). Some researchers are of the opinion that the amount of acid is what causes erosion than just the pH (Low and Alhuthali, 2008). Of all the acids, that which cause heavy erosion are phosphoric acid an hydrochloric acid. Citric acid, on the other hand behaves abnormally. The more the pH of this acid, the worse is the erosion. Most of the commercial drinks have citric and phosphoric acids and gastric juice has hydrochloric acid. Other acids which are erosive are tartaric acid and malic acids, mainly because of their ability to cause chelation with calcium. Thus ability of the acids to chelate with calcium is also an important factor in causing dental erosion. Chelation causes rapid drainage of calcium from the teeth. Some acids are polybasic and have higher chelation properties and can maintain lower pH. Examples of such acids are malic acid, tartaric acid, phosphoric acid and citric acid. Temperature is another important factor. Chemical reaction occurs at a faster rate as the temperature increases. Increase in temperature also increases acidity of the medium, thus contributing to dental erosion (Low et al, 2009). Saliva is an important factor in the prevention of dental erosion and factors which influence the degree of erosion are flow rate, composition of saliva, buffering capacity, clearance rates and pellicle formation. Besides saliva, the structure of the tooth, acquired pellicle and positioning of the tooth in relation to soft tissues are important factors in erosion of enamel (Lussi and Jaeggi, 2008). Frequently vomiting and gastroesophageal reflux contribute to erosion. Professional swimmers and those employed in industries where there is increased exposure to acidic fumes are at increased risk of erosion. Indulging in illicit drug consumption like cocaine and marijuana leads to erosion (Low and Alhuthali, 2008). 2.5. Fruit juices and human teeth Fruits are rich in citric acid and other organic acids. Citric acid exists in water as a mixture of acid anions, hydrogen ions and undissociated acid molecules (Hughes et al, 2000). The pH of the solution and the acid-dissociation constant determine the amount of hydrogen ions. These hydrogen ions attack the surface of the enamel directly, form a complex with calcium ions and remove the calcium from the surface of the enamel. The acid anions too have similar properties and hence citrate has double actions in causing enamel erosion. The citrate in fruit juices also forms a complexes with calcium in the saliva (Hughes et al, 2000). This decreases the supersaturation of calcium in saliva, leading to increase in the driving force for further dissolution of calcium with respect to various other minerals in the teeth. Dilution of juices with water, to some extent has protective effect on enamel. Similarly addition of calcium and fluoride to the drinks too has some protective effect (Lussi and Jaeggi, 2008). 3.0. Techniques for investigating the erosion of enamel Investigation of dental erosion can be done through direct and indirect methods. The most conventional method is the weight loss method in which the specimens of the tooth are weighed at specific intervals like 1 or 2 weeks. Prior to weighing, the specimens are blotted dry and syringed with air. This method is out-dated because of increased risk of errors. The most commonly encountered error occurs during drying which depends on the temperature and humidity of the environment. of the laboratory. Other than this, the process is not continuous and is laborious. In their study, Low and Alhuthali (2008) used a different weighing method to evaluate dental erosion. Only specimens which were clean and caries-free were used and an electronic balance with upto 0.1mg weighing facility was used for weighing. Measurements for weight loss was done with and without stirring. Magnetic rod with 300 revolutions per minute were used for stirring with intentions to stimulate the turbulent flow of drink in the mouth during the process of drinking. Archimedes principle was used for calculation of weight. Wa = W- B Wa= Apparent weight W= Weight of the sample in air B= Buoyancy of the solution used Buoyancy remains the same and the weight after some time is calculated in a similar method as indicated below: Wa (t) = W (t)- B Based on these two results, weight loss at a particular time can be calculated as follows: (Low and Alhuthali, 2008) Fig. 4. Schematic diagrams showing the experimental set-up for (a) the in-situ measurement of weight loss in tooth enamel when immersed in a soft drink over 7 days, and (b) the dental erosion of tooth enamel in Sprite Zero for subsequent analysis of leached Ca2+ concentration by atomic absorption spectroscopy (Low et al, 2009). Microindentation techniques Microindentation is a traditional method of investigation in which a diamond tip is applied into the enamel surface for a given load and time. This test determines the hardness of the enamel and thus indicates the likelihood of erosion and the chances of subsequent erosion. This is because, dissolution of enamel is the first step in the process of erosion. The indentation depth in this technique is 1-10s of micrometers (Barbour et al, 2006). The data obtainable through this method is Vickers hardness number and Knoop hardness number. The technique mainly investigates the indent that is left behind in the material. Traditionally, microindentation has been used to investigate and ascertain the effect of various solutions on the surfaces of the enamel. It is also useful to evaluate the role of salivary pellicle in enamel softening minimization (Barbour et al, 2006). This procedure is much cheaper than than nono-indentation. Nanoindentation techniques This technique is similar to microindentation method, but the indentation depth is 200nm. Data obtainable through this method is reduced elastic modulus in Nm-2 and hardness. The method allows continual monitoring as the indentation occurs. Thus nano indentation methods investigate the load that is displaced at the tip (Barbour et al, 2006). Permanent deformation of the enamel and chances of its subsequent recovery are determined by difference between data pertaining to loading segment and unloading segment. Figure. 5: Typical nano-indentation data and load-displacement data in a sound and polished enamel (Barbour et al. 2006). Profilometry In this method, a stylus is used to scan the surface of the enamel. An adhesive tape or vanish is used to cover the enamel surface, following which the enamel is exposed to erosive agent. Stylus is then used to scan the enamel surface at 10mm per minute rate, thus allowing comparison between regions which are affected with erosion and regions that are not affected. Currently laser profilometry is in vogue and through this technology, it is possible to ascertain the volume and also the depth of erosion. For several decades, dental profilometry using a 20 microns thin stylus that was dragged slowly was used for obtaining image. Currently nanotechnology has been tried for evaluating various aspects of teeth, including dental erosion (Barbour et al, 2006). Figure 6: Image from laser profilometry in 3D. The sides of the enamel were protected with an adhesive tape and the middle section represents the depth and volume of the erosion that occurred (Barbour et al. 2006). Microradiography This technology is mainly used in dental research and development. Through radiation from an X-ray beam, mapping of the density of the mineral over the surface of the enamel can be done with the help of an photographic plate. Three types of microradiography have been identified and they are transverse, longitudinal and wavelength independent type. the most often used type is the microindentation type. Longitudinal microradiography is used for evaluating thick sections and the wavelength-independent type is used for quantification of mineral content (Barbour et al, 2006). Microradiography is most commonly used in the investigation of dental caries and the rate of erosion of teeth. A combination of profilometry nd microradiography is often useful to determine information about dental erosion. It is frquently combined with electron microscopy for investigation of enamel erosion (Barbour et al. 2006). Chemical analysis techniques Techniques which employ chemicals for evaluation of dental erosion measure the quantity of calcium and phosphate released. Through these methods, certain thermodynamics and kinetics of the enamel can be evaluated. The release and uptake of certain minerals like flouride and magnesium, and also dissolution of hydroxypatite can be estimated. Chemical analysis has 2 components, namely, specrophotometry and atomic absorption spectrometry. Atomic absorption spectrometry or AAS is performed using flame atomic-absorption spectrometer. The test is commonly used to evaluate leaching of calcium by soft drinks. The procedure involves measurement of the gas-phase atoms concentration by employing absorption of light. Since most of the samples subjected to this analysis are either solids or liquids, ions or the analyte atoms are vaporized by flame using a furnace. Analytes absorb the light and the concentration of the analyte under study can be determined by estimating the amount of light absorbed. A major disadvantage with this technique is lack of uniformity in the path length and concentration of the atoms of the analyte, affecting the atomisation efficiency of the sample matrix (Tissue, 1996). On the other hand, dissolution of hydroxypatite is evaluated by pH stat which determines the OH-release rate which in turn provides an estimation of hydroxypatite dissolution. Chemical analysis techniques do not allow real time data because only information about net concentration of ions is provided. Microscopy techniques: Scanning electron microscopy Currently, the most widely used microscopic procedure for evaluation of dental erosion is scanning electron microscopy or SEM. The technique is an excellent imaging tool and has the ability to detect both monetite and brushite forms of calcium phosphate. These substances are formed during the process of calcium dissolution. In scanning electron microscopy, images are obtained by scanning the object with high energy beam of electrons in a raster scan pattern. SEM is often used in combination with other tests and useful for evaluation of the microstructure of various dental tissues. An adaptation of scanning microscope is the environmental scanning electron microscope or ESEM. The advantage with this technique is that there is no need to coat the teeth with metals prior to testing and testing can be done even in low vacuum conditions and wet conditions (Barbour et al. 2006). Nekrashevych, Hannig and Stösser (2004) used scanning electron microscopy and profilometry to evaluate the effects of different strengths of citric aci on dental enamel. From their study it was clear that even low strengths of citric acid have an impact on enamel and can cause dental erosion. Researchers have employed ESEM to determine erosion in premolar enamels. Another variant is energy dispersive x-ray spectroscopy or EDX. But this technique is yet in development stage (Barbour et al. 2006). Figure 7: A flame atomic-absorption spectrometer (Tissue, 1996) Transmission electron microscopy In transmission electron microscopy, imaging is done by transmitting a beam of electrons through an ultra thin specimen. The electrons interact through the specimen as they pass through it. Transmission electron microscopy helps in identification of even minor enamel changes. Hannig and Balz (1999) evaluated the effects of salivary pellicle on dental erosion using transmission electron microscopy. Quantitative light-induced fluorescence or QLF This test is useful to ascertain the extent of demineralisation in the enamel and other dental tissues. This technology is still in development stage and is likely to have increasing application in research in future (Barbour et al. 2006). Atomic force microscopy This technique employs probing of the surface of the sample using a cantilever to which a sharp tip is attached. The test can be employed in both wet and dry conditions of the enamel, so no drying is required. However, very few studies have employed this test for evaluation of dental erosion (Barbour et al. 2006). Secondary ion mass spectroscopy or SIMS This test determines the trace elements present in various dental tissues. Thus, this technology is useful in the detection of calcium density in various areas (Barbour et al., 2006). This test is often combined with X-ray microanalysis, so that correlation between morphological and analytical data can be done. 4.0 Conclusion Fruit juices have detrimental effects on dental health, the most common consequence being dental erosion. The acids in the fruit juices drain the calcium content from the enamel and also chelate with calcium, causing erosion. This has been the main cause of the rising rates of dental erosion in the current-day situation. Several techniques have been developed to evaluate and investigate dental erosion, the most poplar of which continues to be scanning electron microscopy. References Amaechi, B.T. & Higham, S.M. (2005). Dental Erosion: Possible Approaches to Prevention and Control. Journal of Dentistry, 33, pps. 243-252. Barbour, M.E. & Rees, J.S. (2004). The Laboratory Assessment of Enamel Erosion: A Review. Journal of Dentistry, 32, pps. 591-602. Deshpande, S.D., and Hugar, S.M. (2004). Dental erosion in children: An increasing clinical problem. Journal of Indian Social Pediatric Preventive Dentistry, 22(3), 118- 127. Friedman, H., 1997. Apatite. Retrieved on 6th October, 2010 from http://www.minerals.net/mineral/phosphat/apatite/apatite.htm Hanning, M., and Balz, M. (1999). Influence of in vivo Formed Salivary Pellicle on Enamel Erosion. Caries Research, 33(5), 372- 379. Hughes, J.A., West, N.X., Parker, D.M., Braak, V.D. & Eddy, M., 2000. Effects of pH and Concentration of Citric, Malic and Lactic Acids on enamel, In Vitro’. Journal of Dentistry, 28, pp. 147-152. Johnson, C. (1998). Biology of the Human Dentition. Retrieved on 6th October, 2010 from http://www.uic.edu/classes/orla/orla312/BHDTwo.html Jensdottir, T., Arnaottir, I.B., Thorsdottir, I. et al. (2004). Relationship between dental erosion, soft drink consumption, and gastroesophageal reflux among Icelanders. Clinical oral investigations, 8(2), 91-96. Low, I.M., Alhuthali, A., and Duraman, N. (2009). Mapping the structure, composition, properties and dental erosion in human enamel. In: Dental Composites. Nova Science Publishers, Inc. Low, I.M., and Alhuthali, A. (2008). In-situ monitoring of dental erosion in tooth enamel when exposed to soft drinks. Materials Science and Engineering, 243–247. Low, I.M., Duraman, N., Mahmood, U. (2008). Mapping the structure, composition and mechanical properties of human teeth. 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