title: Nano-structural and compositional basis of devitalized tooth fragility.
abstract: OBJECTIVE
  Increased tooth fragility after devitalization is commonly observed but there is no definite mechanistic explanation for such phenomenon. Therefore, it is important to analyze more profoundly structural and compositional properties of this altered form of dentin. The present study investigates the differences between normal and devitalized dentin using advanced techniques.
  
  
  METHODS
  Atomic force microscopic imaging (AFM), energy dispersive X-ray analysis (EDX) and micro-Raman spectroscopy were performed on 16 dentin specimens, eight vital and eight that underwent root-canal treatment at least two years before extraction and had no infection in root canals before or after devitalization.
  
  
  RESULTS
  The mean size of mineral crystals showed by AFM was larger in devitalized than in healthy dentin in the same age category. AFM phase shifts in devitalized cases revealed altered mechanical characteristics and suggested differences in composition of material between devitalized teeth and healthy controls. No significant difference in Ca/P ratio between vital and devitalized teeth was found using EDX. However, micro-Raman analyses showed that in devitalized teeth, apart from hydroxyapatite, dentin contained significant amounts of apatite phases with lower calcium content: octacalcium phosphate, dicalcium phosphate dihydrate and tricalcium phosphate.
  
  
  CONCLUSIONS
  Differences between vital and devitalized dentin bring new insights into the basis of devitalized tooth fragility. Larger mineral crystals could account for decreased mechanical strength in devitalized teeth. Moreover, calcium-phosphate phases with lower Ca content have lower material strength, and the presence of these phases in devitalized teeth may explain their increased fragility.
authors.affiliation: University of Belgrade, School of Medicine, Institute of Anatomy, Laboratory for Anthropology, 4/2 Dr. Subotica, 11000 Belgrade, Serbia.
authors.forename: Ksenija
authors.initials: K
authors.lastname: Zelic
authors.affiliation: University of Belgrade, School of Medicine, Institute of Anatomy, Laboratory for Anthropology, 4/2 Dr. Subotica, 11000 Belgrade, Serbia.
authors.forename: Petar
authors.initials: P
authors.lastname: Milovanovic
authors.affiliation: University of Belgrade, INS Vinca, Laboratory of Atomic Physics, 12-14 Mike Alasa, 11001 Belgrade, Serbia.
authors.forename: Zlatko
authors.initials: Z
authors.lastname: Rakocevic
authors.affiliation: University of Belgrade, Institute of Physics, Center for Solid State Physics and New Materials, 118 Pregrevica, 11000 Belgrade, Serbia.
authors.forename: Sonja
authors.initials: S
authors.lastname: Askrabic
authors.affiliation: University of Belgrade, INS Vinca, Laboratory of Atomic Physics, 12-14 Mike Alasa, 11001 Belgrade, Serbia.
authors.forename: Jelena
authors.initials: J
authors.lastname: Potocnik
authors.affiliation: University of Belgrade, Faculty of Physics, 12-16 Studentski trg, 11000 Belgrade, Serbia.
authors.forename: Miroslav
authors.initials: M
authors.lastname: Popovic
authors.affiliation: University of Belgrade, School of Medicine, Institute of Anatomy, Laboratory for Anthropology, 4/2 Dr. Subotica, 11000 Belgrade, Serbia. Electronic address: marijadjuric5@gmail.com.
authors.forename: Marija
authors.initials: M
authors.lastname: Djuric
mesh_terms: D006801:Humans; D018625:Microscopy, Atomic Force; D008855:Microscopy, Electron, Scanning; D049329:Nanostructures; D012390:Root Canal Therapy; D013052:Spectrometry, X-Ray Emission; D013059:Spectrum Analysis, Raman
keywords: Atomic force microscopy; Dentin; Endodontics; Energy dispersive X-ray analysis; Micro-Raman spectroscopy