title: Diagenesis-inspired reaction of magnesium ions with surface enamel mineral modifies properties of human teeth.
abstract: Mineralized tissues such as teeth and bones consist primarily of highly organized apatitic calcium-phosphate crystallites within a complex organic matrix. The dimensions and organization of these apatite crystallites at the nanoscale level determine in part the physical properties of mineralized tissues. After death, geological processes such as diagenesis and dolomitization can alter the crystallographic properties of mineralized tissues through cycles of dissolution and re-precipitation occurring in highly saline environments. Inspired by these natural exchange phenomena, we investigated the effect of hypersalinity on tooth enamel. We discovered that magnesium ions reacted with human tooth enamel through a process of dissolution and re-precipitation, reducing enamel crystal size at the surface of the tooth. This change in crystallographic structure made the teeth harder and whiter. Salt-water rinses have been used for centuries to ameliorate oral infections; however, our discovery suggests that this ancient practice could have additional unexpected benefits.
  
  
  
  Here we describe an approach inspired by natural geological processes to modify the properties of a biomineral - human tooth enamel. In this study we showed that treatment of human tooth enamel with solutions saturated with magnesium induced changes in the nanocrystals at the outer surface of the protective enamel layer. As a consequence, the physical properties of the tooth were modified; tooth microhardness increased and the color shade became whiter, thus suggesting that this method could be used as a clinical treatment to improve dental mechanical properties and esthetics. Such an approach is simple and straightforward, and could also be used to develop new strategies to synthesize and modify biominerals for biomedical and industrial applications.
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
authors.forename: Mohamed-Nur
authors.initials: MN
authors.lastname: Abdallah
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
authors.forename: Hazem
authors.initials: H
authors.lastname: Eimar
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
authors.forename: David C
authors.initials: DC
authors.lastname: Bassett
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
authors.forename: Martin
authors.initials: M
authors.lastname: Schnabel
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
authors.forename: Ovidiu
authors.initials: O
authors.lastname: Ciobanu
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada.
authors.forename: Valentin
authors.initials: V
authors.lastname: Nelea
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada; Department of Anatomy and Cell Biology, Faculty of Medicine, McGill University, H3A 0C7 Montreal, QC, Canada.
authors.forename: Marc D
authors.initials: MD
authors.lastname: McKee
authors.affiliation: Department of Mining and Materials Engineering, McGill University, H3A 0E8 Montreal, QC, Canada.
authors.forename: Marta
authors.initials: M
authors.lastname: Cerruti
authors.affiliation: Faculty of Dentistry, McGill University, H3A 0C7 Montreal, QC, Canada. Electronic address: faleh.tamimimarino@mcgill.ca.
authors.forename: Faleh
authors.initials: F
authors.lastname: Tamimi
mesh_terms: D000328:Adult; D003743:Dental Enamel / Q000737:chemistry*; D005260:Female; D006801:Humans; D008274:Magnesium / Q000737:chemistry*; D008297:Male; D054712:Salinity
chemical_list: D008274:Magnesium
keywords: Crystallographic structure; Hypersaline environment; Ionic exchange; Magnesium ions; Mineralized tissues; Tooth enamel