Ultrastructural properties of bone mineral of control and tiludronate-treated osteoporotic rat.

Bisphosphonates have been widely used in the treatment of human bone pathologies including osteoporosis. In this case, bisphosphonates have been shown to reduce bone resorption, thereby increasing the mass and mechanical resistance of bone. Determining the effects of these molecules on the properties of the bone apatite crystals could provide a better insight into the mechanism of bisphosphonate/bone interaction. The aim of this study was to determine the ultrastructural effects of a third generation bisphosphonate (tiludronate) on the morphology, size, distribution, chemical composition, and structure of apatite crystals in bone (trabecular) in a rat osteoporotic model. Four groups of rats were studied: (1) sham operated, (2) untreated ovariectomized (OVX), (3) OVX rats which received 35 mg/kg of tiludronate, (4) OVX rats which received 160 mg/kg of tiludronate. The rats of groups 3 and 4 received tiludronate orally in 2 consecutive days every week for 1 year. Scanning electron microscopy (SEM), high and low resolution transmission electron microscopy (TEM), and electron microprobe analysis (EDX) were used for the ultrastructural characterization of the bone mineral. This study demonstrated that tiludronate slightly increased the width of bone apatite crystals without changing any other crystal characteristics.

Scanning electron microscopy and electron probe microanalyses of the crystalline components of human and animal dental calculi.

A review of the use of scanning electron microscopy (SEM) and electron probe microanalyses in the study of dental calculus showed that such studies provided confirmatory and supplementary data on the morphological features of human dental calculi but gave only limited information on the identity of the crystalline or inorganic components. This study aimed to explore the potential of combined SEM and microanalyses in the identification of the crystalline components of the human and animal dental calculi. Human and animal calculi were analyzed. Identification of the crystalline components were made based on the combined information of the morphology (SEM) and Ca/P molar ratios of the crystals with the morphology and Ca/P molar ratio of synthetic calcium phosphates (brushite or DCPD; octacalcium phosphate, OCP; Mg-substituted whitlockite, beta-TCMP; CO3-substituted apatite, (CHA); and calcite. SEM showed similarities in morphological features of human and animal dental calculi but differences in the forms of crystals present. Microanalyses and crystal morphology data suggested the presence of CaCO3 (calcite) and CHA in the animal (cat, dog, tiger) and of OCP, beta-TCMP and CHA in human dental calculi. X-ray diffraction and infrared (IR) absorption analyses confirmed these results. This exploratory study demonstrated that by taking into consideration what is known about the crystalline components of human and animal dental calculi, combined SEM and microanalyses can provide qualitative identification.

Some physico-chemical properties of deciduous enamel of children with and without pre-natal fluoride supplementation (PNF).

Physico-chemical investigations of enamel from deciduous teeth of a small number of children with and without pre-natal fluoride supplementation (PNF) exhibited the following differences between the PNF and non-PNF enamel, with the former showing: (a) more homogeneous and less extensive patterns of acid-etching; (b) denser crystal populations in intra-prismatic regions; (c) larger prism dimensions; (d) greater total mineral density (wt%ash); (e) higher degree of crystallinity; (f) smaller a-axis dimensions; and (g) more fluoride and less carbonate contents. On the basis of these preliminary findings, further studies with larger numbers of samples would seem appropriate.