Carbonated hydroxyapatites precipitated in the presence of Ti

International audienc

Synthesis, characterization and high temperature analysis of Al-containing hydroxyapatites

International audienc

High resolution electron microscopy study of crystal growth mechanisms in chicken bone composites

International audienc

Heterogeneous nucleation of calcium phosphate salts at a solid/liquid interface examined by scanning angle reflectometry

International audienc

High Resolution Electron Microscopy: Structure and Growth Mechanisms of Human Dentin Crystals

International audienc

Injectable calcium phosphate hydraulic cement (CPHC) used for periodontal tissue regeneration: A study of a dog model

Injectable calcium phosphate hydraulic cement (CPHC) is a new bone substitute family. This study aimed to evaluate the use of CPHC in surgical periodontitis-simulating defects in a dog model. CPHC was obtained by adding powder mixtures of different calcium phosphates with different solubility. Alveolar bone was removed by drilling over the mesial and distal roots of the 2nd mandibular premolar in six dogs. The defects were randomly selected, three were untreated and six treated. The defects had a depth of 6 mm and a width of 3 mm. The animals were sacrificed after 9 months and samples prepared, with no decalcification, for histological evaluation. Seventy-nine percent of the root was covered by bone in the experimental defects, compared to 41% of the root for the control defects. Bone height was significantly higher for the experimental defects (4.9 ±0.9 mm) than for the control defects (1.4 ±0.5 mm). After 9 months, 97 ±6% of the CPHC was degradated and replaced by bone. This study proves the interest of this cement because of the particularly high level of periodontal bone regeneration. The ability of the cement to be easily injected and shaped in bone defects and the immediate immobilization of the teeth after hardening is notable

Multiphoton microscopy for caries detection

International audienceMultiphoton microscopy (MPM) is a nonlinear high-resolution technique that can be applied to collagen studies such as collagen type I denaturation during caries process. The MPM lies in its simultaneous image creation based on the fluorescence signals produced by a multiphoton excitation (2-photon excited fluorescence [2PEF]) and a coherent nonlinear phenomenon, second harmonic generation (SHG). This study aims to investigate the structural modifications during the dentin caries process by monitoring the variations of the SHG and the SHG/2PEF ratio recorded by nonlinear optical spectroscopy (NLOS). The International Caries Detection and Assessment System (ICDAS) was used as a clinical reference in vitro.To this end, teeth for each ICDAS score were selected and longitudinal sections through the caries lesion were performed. SHG and 2PEF images and spectra were recorded for each ICDAS score (0 to 6).2PEF and SHG images highlighted the microarchitecture and optical properties of the collagen denaturation in dentin during the caries process. The SHG images of carious dentin demonstrated a destruction of the collagen matrix. The variation of intensity of the 2PEF, SHG and the ratio SHG/2PEF allowed the merge of ICDAS scores: ICDAS 0/1; ICDAS 2/3; ICDAS 4/5/6. The new groups tend to be similar to the International Caries Classification and Management System (ICCMS). The 2PEF and SHG intensities and the ratio SHG/2PEF are highly altered during the caries process. The ratio SHG/2PEF is a relevant parameter to monitor the caries evolution and it defined three stages: initial lesion (ICDAS 0/1), moderate lesion (ICDAS 2/3) and extensive lesion (ICDAS 4/5/6). The development of a clinical device based on the nonlinear optics will bring a valuable diagnostic tool for caries detection in an everyday practice