Nanomaterials in preventive dentistry

Journal name:
Nature Nanotechnology
Volume:
5,
Pages:
565–569
Year published:
DOI:
doi:10.1038/nnano.2010.83
Published online

Abstract

The prevention of tooth decay and the treatment of lesions and cavities are ongoing challenges in dentistry. In recent years, biomimetic approaches have been used to develop nanomaterials for inclusion in a variety of oral health-care products. Examples include liquids and pastes that contain nano-apatites for biofilm management at the tooth surface, and products that contain nanomaterials for the remineralization of early submicrometre-sized enamel lesions. However, the treatment of larger visible cavities with nanomaterials is still at the research stage. Here, we review progress in the development of nanomaterials for different applications in preventive dentistry and research, including clinical trials.

At a glance

Figures

  1. Bioadhesion and biofilm management in the oral cavity.
    Figure 1: Bioadhesion and biofilm management in the oral cavity.

    a, Bioadhesion in the oral cavity. Proteins interact with the enamel surface to form a proteinaceous pellicle layer. Bacteria adhere to this conditioning film through calcium bridges and specific adhesin–receptor interactions (purple and red). Bacteria are surrounded by an extracellular matrix of water-insoluble glucans, and they communicate through quorum sensing (arrows). b, Cross-section of a human molar tooth showing the enamel, dentine and pulp chamber. c, Easy-to-clean nanocomposite surface coating. The low-surface-free-energy coating (blue) causes poor protein–protein binding. Shear forces in the mouth (yellow arrow) can easily detach the outer layer of the pellicle and bacterial biofilm from the surface. d, CPP–ACP inhibits bacterial adhesion and oral biofilm formation. CPP attaches to the pellicle and limits bacterial adhesion. It competes with calcium for plaque–calcium binding sites (I), and decreases the amount of calcium bridging the pellicle and bacteria, and between the bacterial cells. Specific receptor molecules (red) in the pellicle layer and on the bacterial surfaces (brown) are blocked, further reducing adhesion and co-adhesion (II). This affects the viability of the bacteria (III).

  2. Early stages of tooth decay caused by bacterial biofilm.
    Figure 2: Early stages of tooth decay caused by bacterial biofilm.

    Bacteria metabolize sugar and other carbohydrates to produce lactate (HL) and other acids that, in turn, dissociate to form H+ ions that demineralize the enamel beneath the surface of the tooth; calcium and phosphate are dissolved in the process. This is known as a white-spot lesion. Owing to reprecipitation, a pseudo-intact surface layer (red arrow) is observed on top of the body of the carious lesion in this early stage of tooth decay. This pseudo-intact layer is permeable to ions (indicated by white chevrons).

  3. Hierarchical structure of the dental enamel.
    Figure 3: Hierarchical structure of the dental enamel.

    Dental enamel is a masterpiece of bioceramics, containing structures at different hierarchical levels from the microscale down to the nanoscale. The enamel is composed of three-dimensionally organized nanosized hydroxyl apatite crystallites (a,b,d) that are arranged into micrometre-sized prisms (c,e). a, Atomic force microscope and b,c, scanning electron microscope images of the enamel surface. d, Transmission electron microscope and e, scanning electron microscope images of a cross-section of the enamel.

  4. Dental erosion caused by acidic beverages or food in the oral cavity.
    Figure 4: Dental erosion caused by acidic beverages or food in the oral cavity.

    Low pH, caused by acidic beverages or gastric juices (pH 1–4), destroys the enamel surface by partial and complete dissolution of the enamel crystallites, resulting in the release of Ca2+ and HPO42− ions. This loosens the microstructure of the enamel and hydroxyl apatite crystallites (pale blue) become demineralized, or are lost.

References

  1. Selwitz, R. H., Ismail, A. I. & Pitts, N. B. Dental caries. Lancet 369, 5159 (2007).
  2. Takahashi, N. & Nyvad, B. Caries ecology revisited: microbial dynamics and the caries process. Caries Res. 42, 409418 (2008).
  3. Filoche, S., Wong, L. & Sissons, C. H. Oral biofilms: emerging concepts in microbial ecology. J. Dent. Res. 89, 818 (2010).
  4. Hannig, C. & Hannig, M. The oral cavity - a key system to understand substratum-dependent bioadhesion on solid surfaces in man. Clin. Oral Investig. 13, 123139 (2009).
  5. Kolenbrander, P. E. et al. Bacterial interactions and successions during plaque development. Periodontol. 2000 42, 4779 (2006).
  6. Sarikaya, M., Tamerler, C., Jen, A. K., Schulten, K. & Baneyx, F. Molecular biomimetics: nanotechnology through biology. Nature Mater. 2, 577585 (2003).
  7. Khang, D., Carpenter, J., Chun, Y. W., Pareta, R. & Webster, T. J. Nanotechnology for regenerative medicine. Biomed. Microdevices doi:10.1007/s10544-008-9264–6 (2008).
  8. Blossey, R. Self-cleaning surfaces-virtual realities. Nature Mater. 2, 301306 (2003).
  9. Solga, A., Cerman, Z., Striffler, B. F., Spaeth, M. & Barthlott, W. The dream of staying clean: Lotus and biomimetic surfaces. Bioinspir. Biomim. 2, 126134 (2007).
  10. Hannig, M., Kriener, L., Hoth-Hannig, W., Becker-Willinger, C. & Schmidt, H. Influence of nanocomposite surface coating on biofilm formation in situ . J. Nanosci. Nanotechnol. 7, 46424648 (2007).
  11. Baier, R. E. Surface behaviour of biomaterials: the theta surface for biocompatibility. J. Mater. Sci. Mater. Med. 17, 10571062 (2006).
  12. Rahiotis, C., Vougiouklakis, G. & Eliades, G. Characterization of oral films formed in the presence of a CPP-ACP agent: an in situ study. J. Dent. 36, 272280 (2008).
  13. Reynolds, E. C., Cai, F., Shen, P. & Walker, G. D. Retention in plaque and remineralization of enamel lesions by various forms of calcium in a mouthrinse or sugar-free chewing gum. J. Dent. Res. 82, 206211 (2003).
  14. Reynolds, E. C. Calcium phosphate-based remineralization systems: scientific evidence? Aust. Dent. J. 53, 268273 (2008).
  15. Reynolds, E. C. Remineralization of enamel subsurface lesions by casein phosphopeptide-stabilized calcium phosphate solutions. J. Dent. Res. 76, 15871595 (1997).
  16. Cross, K. J., Huq, N. L. & Reynolds, E. C. Casein phosphopeptides in oral health - chemistry and clinical applications. Curr. Pharm. Des. 13, 793800 (2007).
  17. Rose, R. K. Binding characteristics of streptococcus mutans for calcium and casein phosphopeptide. Caries Res. 34, 427431 (2000).
  18. Venegas, S. C., Palacios, J. M., Apella, M. C., Morando, P. J. & Blesa, M. A. Calcium modulates interactions between bacteria and hydroxyapatite. J. Dent. Res. 85, 11241128 (2006).
  19. Bertassoni, L. E., Habelitz, S., Kinney, J. H., Marshall, S. J. & Marshall, G. W. Jr Biomechanical perspective on the remineralization of dentin. Caries Res. 43, 7077 (2009).
  20. Fu-Zhai Cui, F. Z. & Ge, J. New observations of the hierarchical structure of human enamel, from nanoscale to microscale. J. Tissue Eng. Regen. Med. 1, 185191 (2007).
  21. Wang, L., Guan, X., Yin, H., Moradian-Oldak, J. & Nancollas, G. H. Mimicking the self-organized microstructure of tooth enamel. J. Phys. Chem. C 112, 58925899 (2008).
  22. Imbeni, V., Kruzic, J. J., Marshall, G. W., Marshall, S. J. & Ritchie, R. O. The dentin-enamel junction and the fracture of human teeth. Nature Mater. 4, 229232 (2005).
  23. Hannig, C., Berndt, D., Hoth-Hannig, W. & Hannig, M. The effect of acidic beverages on the ultrastructure of the acquired pellicle - an in situ study. Arch. Oral. Biol. 54, 518526 (2009).
  24. Morgan, M. V. et al. The anticariogenic effect of sugar-free gum containing CPP-ACP nanocomplexes on approximal caries determined using digital bitewing radiography. Caries Res. 42, 171184 (2008).
  25. Cai, F. et al. Effect of addition of citric acid and casein phosphopeptide orphous calcium phosphate to a sugar-free chewing gum on enamel remineralization in situ . Caries Res. 41, 377383 (2007).
  26. Iijima, Y. et al. Acid resistance of enamel subsurface lesions remineralized by a sugar-free chewing gum containing casein phosphopeptide-amorphous calcium phosphate. Caries Res. 38, 551556 (2004).
  27. Cross, K. J., Huq, N. L., Palamara, J. E., Perich, J. W. & Reynolds, E. C. Physicochemical characterization of casein phosphopeptide-amorphous calcium phosphate nanocomplexes. J. Biol. Chem. 280, 1536215369 (2005).
  28. Reynolds, E. C. et al. Fluoride and casein phosphopeptide-amorphous calcium phosphate. J. Dent. Res. 87, 344348 (2008).
  29. Roveri, N. et al. Synthetic biomimetic carbonate-hydroxyapatite nanocrystals for enamel remineralization. Adv. Mater. Res. 47–50, 821824 (2008).
  30. Li, L. et al. Repair of enamel by using hydroxyapatite nanoparticles as the building blocks. J. Mater. Chem. 18, 40794084 (2008).
  31. Roveri, N., Palazzo, B. & Iafisco, M. The role of biomimetism in developing nanostructured inorganic matrices for drug delivery. Expert Opin. Drug Deliv. 5, 861877 (2008).
  32. Roveri, N. et al. Surface enamel remineralisation: biomimetic apatite nanocrystals and fluoride ions different effects. J. Nanomaterials 2009, 746383 (2009).
  33. Lv, K., Zhang, J., Meng, X. & Li, X. F. Remineralization effect of the nano-HA toothpaste on artificial caries. Key Eng. Mat. 330–332, 267270 (2009).
  34. Nakashima, S., Yoshie, M., Sano, H. & Bahar, A. Effect of a test dentifrice containing nano-sized calcium carbonate on remineralization of enamel lesions in vitro . J. Oral Sci. 51, 6977 (2009).
  35. Shibata, Y., He, L. H., Kataoka, Y., Miyazaki, T. & Swain, M. V. Micromechanical property recovery of human carious dentin achieved with colloidal nano-beta-tricalcium phosphate. J. Dent. Res. 87, 233237 (2008).
  36. Vollenweider, M. et al. Remineralization of human dentin using ultrafine bioactive glass particles. Acta Biomater. 3, 936943 (2007).
  37. Wang, L., Guan, X., Moradian-Oldak, J. & Nancollas, G. H. Amelogenin assemblies promote the formation of elongated apatite microstructures in a controlled crystallization system. J. Phys. Chem. 111, 63986404 (2007).
  38. Fan, Y., Sun, Z., Wang, R., Abbott, C. & Moradian-Oldak, J. Enamel inspired nanocomposite fabrication through amelogenin supramolecular assembly. Biomaterials 28, 30343042 (2007).
  39. Fan, Y., Sun, Z. & Moradian-Oldak, J. Controlled remineralization of enamel in the presence of amelogenin and fluoride. Biomaterials 30, 478483 (2009).
  40. Tao, J., Pan, H., Zeng, Y., Xu, X. & Tang, R. Roles of amorphous calcium phosphate and biological additives in the assembly of hydroxyapatite nanoparticles. J. Phys. Chem. B 111, 1341013418 (2007).
  41. Kirkham, J. et al. Self-assembling peptide scaffolds promote enamel remineralization. J. Dent. Res. 86, 426430 (2007).
  42. Fowler, C. E., Li, M., Mann, S. & Margolis, H. C. Influence of surfactant assembly on the formation of calcium phosphate materials - a model for dental enamel formation. J. Mater. Chem. 15, 33173325 (2005).
  43. Chen, H., Clarkson, B. H., Sun, K. & Mansfield, J. F. Self-assembly of synthetic hydroxyapatite nanorods into an enamel prism-like structure. J. Colloid Interf. Sci. 288, 97103 (2005).
  44. Palazzo, B. et al. Amino acid synergetic effect on structure, morphology and surface properties of biomimetic apatite nanocrystals. Acta Biomater. 5, 12411052 (2009).
  45. Chen, H. et al. Acellular synthesis of a human enamel-like microstructure. Adv. Mater. 18, 18461851 (2006).
  46. Yamagishi, K. et al. Materials chemistry: a synthetic enamel for rapid tooth repair. Nature 433, 819 (2005).
  47. Iijima, Y. & Moradian-Oldak, J. Control of apatite crystal growth in a fluoride containing amelogenin-rich matrix. Biomaterials 26, 15951603 (2005).
  48. He, G., Dahl, T., Veis, A. & George, A. Dentin matrix protein 1 initiates hydroxyapatite formation in vitro . Connect. Tissue Res. 44, 2405 (2003).
  49. Veis, A. Materials science. A window on biomineralization. Science 307, 14191420 (2005).
  50. Moradian-Oldak, J. Amelogenins: assembly, processing and control of crystal morphology. Matrix Biol. 20, 293305 (2001).

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Affiliations

  1. Clinic of Operative Dentistry, Periodontology and Preventive Dentistry, University Hospital, Saarland University, Building 73, D-66421 Homburg/Saar, Germany

    • Matthias Hannig
  2. Clinic of Conservative Dentistry, Faculty of Medicine 'Carl Gustav Carus', Technical University Dresden, Fetscherstr. 74, 01307 Dresden, Germany.

    • Christian Hannig

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