New strategies in dental caries prevention: experimental study on casein phosphopeptides G.F. FERRAZZANO, T. CANTILE, A. INGENITO, L. CHIANESE*, M. QUARTO* ABSTRACT. Aim Casein phosphopeptides (CPPs) are phosphorylated casein-derived peptides produced by proteolytic digestion of αs1-, αs2- and β-casein in vitro or in the digestive tract. CPPs exhibit anti-caries activity relates to their capability to localise high levels of amorphous Ca2+ phosphate on tooth surface. Aim of this study is in vitro testing of the capability of CPPs to prevent demineralisation and promote remineralisation of early enamel lesions. Materials and Methods 159 samples of dental enamel were divided into 3 groups, which subsequently underwent 3 different chemical treatments: the samples from group I (control group) were preserved in distilled water; the samples from group II were treated with a demineralising solution for producing artificial caries; the samples from group III underwent the same treatment as group II, but with the addition of CPPs. The effects of these procedures were evaluated by quantitative analysis (change in weight and calcium titration) and qualitative analysis (SEM). Statistics Statistical analysis of the results was performed using ANOVA. Results In presence of CPPs, acid dissolution of human enamel is reduced by over 50% in vitro. Conclusion Our results demonstrate that CPPs could be a valid preventive system against demineralisation of early enamel lesions. KEYWORDS: Caries, Prevention, Casein phosphopeptides.
Introduction In Italy, as in other industrialised countries, there is an high prevalence of tooth decay, particularly among young people [de Almeida et al., 2003; Ferro and Meneghetti, 2005; Lazzati et al., 1998]. Even though the prevalence of dental caries has decreased through the use of preventive systems (fluoride prophylaxis, fluoride toothpastes, control of oral hygiene, sealants) [Simonsen, 2002; Jacobsen and Young, 2003], tooth decay is still one of the most prevalent chronic diseases of people worldwide; individuals are susceptible to dental caries throughout their lifetime [Selwitz et al., 2007]. In a study conducted on 1500 Indian preschool children it emerged that the overall prevalence of dental caries
Department of Dentistry and Maxillofacial Surgery *Department of Nutrition, Agricultural Science Faculty University of Naples “Federico II”, Naples (Italy) e-mail:
[email protected]
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was 54.1%. In 3 year olds, 42.6% had one or more carious lesions and in 4 and 5 year olds 50.7% and 60.9%, respectively, had one or more carious lesions [Mahejabeen et al., 2006]. In Saudi Arabia the oral status of a random sample of 300 children (6 to 7-year-olds) was investigated: caries were diagnosed in 288 (96%) of the children, and only 4% were clinically caries free [Al-Malik and Rehbini, 2006]. A study carried out in Germany on 43950 12 year olds children has shown that the mean DMFT score was 0.98 [Schulte et al., 2006]. From a study conducted in the city of Naples it emerged that caries prevalence was 81% in 101 children (age range 5-18 years); the sample mean values were 3.5 (SD=3.79) for DMFT and 3.8 (SD=3.39) for dmft [Ferrazzano et al., 2006]. This result showed the WHO requirement of 1979, according to which the DMFT for 12 year-olds should be less than 3.0 in the year 2000, was not yet reached [Chen et al., 1997; World Health Report, 2002]. This highlights the requirement for the development 183
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of a non-toxic, anticariogenic agent that could be added to toothpaste and mouthwash. It would be particularly useful if the anticariogenic agent was a natural food derivative [Reynolds, 1998]. The food group most recognised as exhibiting anticaries activity is dairy products [Addeo et al., 1994; Ferranti et al., 1997]. For this reason, the research has focused on isolating protective factors from milk to use as food additives or in oral hygiene products to reduce cariogenicity. The substances that have anticariogenic properties are calcium, phosphate, casein, and lipids [Aimutis, 2004]. Casein phosphopeptides (CPPs) are phosphorylated casein-derived peptides produced by proteolytic digestion of αs1-, αs2-, and β-casein in vitro or in the digestive tract [Cai et al., 2003; Walker et al., 2006; Ramalingam et al., 2005]. CPPs, containing the sequence Ser(P)-Ser(P)-Ser-(P)-GluGlu, stabilise nanoclusters of amorphous calcium phosphate (ACP) in metastable solution. These multiple phosphoseryl residues of the CPPs bind to form nanoclusters of ACP in supersaturated solutions, preventing growth to the critical size required for phase transformations. CPPs-ACP localise ACP in dental plaque, which buffers the free calcium and phosphate ion activities, helping to maintain a state of supersaturation with respect to tooth enamel, depressing demineralisation and enhancing remineralisation [Cross et al., 2004; Cross et al., 2005]. Laboratory, animal and human in situ experiments have demonstrated that synthetic casein phosphopeptide-amorphous calcium phosphate (CPPs-ACP) nanocomplexes contained in mouthrinses and sugarfree chewing gums are anticariogenic [Shen et al., 2001; Reynolds et al., 2003; Iijima et al., 2004]. Aim of this study is to test in vitro, through a quantitative and qualitative analysis, the capability of CPPs to prevent demineralisation and promote remineralisation of early enamel lesions.
Materials and methods In the present study, 53 human molars, extracted for orthodontic reasons or impaction, were cleaned with sterile gauze imbibed in distilled water and stored at 4°C in sterile containers with 5% formalin solution. The roots were then cut and the crowns polished with pumice dust and non-fluoride toothpaste, using a circular brush with nylon bristles mounted on a dental handpiece; they were then rinsed in distilled water. Subsequently, the crowns were sectioned, through microtome, in 3 fragments resulting in a total of 159 184
samples on each of which, through red acid-resistant nail varnish, an area of enamel of 5x2 mm was delimited. These samples were divided again into three groups so that, in each of them, there was a representative fragment of each tooth. Each of the three groups was submitted to a different chemical experimental treatment (Table 1). The samples from group I (control group) were preserved in distilled water at 4°C. Each sample, belonging to group II, was immersed for 4 days (with one change of solution after 48 hours) in 50 ml of demineralising solution, containing lactic acid (0.1M/l), 0.02% of carboxymethylcellulose (Akzo Nobel, Netherlands), at pH 4.8 and 37°C, for producing, on its surface, artificial caries. The samples belonging to group III underwent the same treatment as group II, but with the addition of a remineralising agent (CPPs 1%). All samples were submitted to a quantitative and qualitative analysis with the aim of evaluating and quantifying the preventive effectiveness of CPPs. Quantitative analysis measures the samples’ weight changes and the calcium concentration of the solutions after the chemical treatments. Weight changes were calculated by a digital analytical scale with a sensitivity of 0.01 mg (Gibertini Electronics, Novate Milan, Italy). All samples were weighed before (t0) and after (t96) the treatments. The amount of calcium released by the teeth in solution was determined by compleximetric titration with EDTA-Na2 (disodium ethylenediamine tetra-acetate) using Eriochrome Black T as an indicator. The calcium concentration in solution was calculated before (t0) and after the treatments (t96). The results obtained were analysed by ANOVA, using SPSS 10.0. The micro-morphological alterations showed on the samples following the chemical treatments were evaluated at Scanning Electron Microscope (SEM) observation (Stereoscan 250 MK3s, Cambridge, UK).
Results The samples belonging to the control group (group I) were not submitted to any chemical treatment and
Samples
Chemical Treatments
Group I distilled water at 4°C Group II acid solution at pH 4.8 (lactic acid 0.1 M/l; CMC 0.02%) Group III acid solution at pH 4.8 containing CPPs (lactic acid 0.1 M/l; CMC 0.02%; CPPs 1%)
TABLE 1 - Summary of the solutions used. EUROPEAN JOURNAL OF PAEDIATRIC
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quantitative analysis gave as a result a mean weight change and a mean change in the calcium released in solution I of ± 0 mg. From the data processing it is inferred that the mean weight change, related to the samples treated with the demineralising solution (group II), is 1.43 ± 0.49 mg (Fig. 1); the mean change in the calcium released in solution II, following the dissolutive action on the enamel, is 0.86 ± 0.28 mg (Fig. 2). The samples belonging to group III, in which the demineralising action has been performed in presence of CPPs, show a mean weight change of 0.76 ± 0.27 mg (Fig. 3); whereas the mean change in the calcium released in solution III corresponds to 0.49 ± 0.18 mg (Fig. 4). The samples belonging to the first group (control group) show, at SEM, a healthy, smooth and regular
The present study shows that the CPPs, if used in acid solutions, are able to inhibit the process of enamel demineralisation, in vitro. Analysis of results of the mean weight change
FIG. 1 - Distribution of weight changes (group II).
FIG. 2 - Distribution of calcium changes (group II).
FIG. 3 - Distribution of weight changes (group III).
FIG. 4 - Distribution of calcium changes (group III).
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enamel surface (Fig. 5). At the SEM observation of the samples belonging to the second group, a lesion could be detected having an average depth of about 200 µm with a superficial micro-morphology “etched-like” for the presence of excavations that are 4 to 20 µm deep (Fig. 6). On the samples belonging to the third group, under SEM, one cannot note the presence of deep lesions, but it is possible to appreciate one slightly irregular surface with a rough look, due to the acid pH (Fig. 7).
Discussion
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FIG. 5 - Healthy enamel surface (group I) ( 50x).
FIG. 6 -
which occurred in our study leads us to affirm that the effects of demineralisation brought about in vitro in presence of remineralising factors are appreciably reduced. In fact, the samples of group II undergo, on average, a loss double than those of group III. The difference between the mean weight change and the mean change in the calcium released in solution for group II and III is, also, statistically significant (P
