Dens invaginatus: a qualitative-quantitative analysis. Case report of an upper second molar.

Dens invaginatus (D.I.) is a developmental anomaly caused by the infolding of the surface of a tooth crown before calcification has occurred. Its aetiology is controversial and remains unclear. It occurs in all dentitions with a prevalence that ranges from 0.25% to 7.74% and is mostly seen in the maxillary permanent incisors, particularly in the lateral incisors. Posterior teeth are infrequently involved. The purpose of this study was to investigate the morpho-structure of a second upper molar dens invaginatus compared with a control tooth. Ground and decalcified sections were prepared and histo-morphological evaluation of dental tissues was performed by using light microscopy, microradiography, and confocal laser scanning microscopy analysis (CLSM). The mechanical behaviour was tested by means of microhardness (HV) test. The results of our investigation showed structural anomalies of hard tissues, such as a difference in enamel prism diameter, in number and diameter of peripulpal dentinal tubules and in surface and diameter of cementocyte lacunae between D.I. and control tooth.

Reconstruction of extensive long bone defects in sheep using resorbable bioceramics based on silicon stabilized tricalcium phosphate.

In this study we evaluated the performance of Skelite, a resorbable bioceramic based on silicon stabilized tricalcium phosphate (Si-TCP), in promoting the repair of a large-sized, experimentally induced defect in a weight-bearing long bone sheep model. Eighteen 2-year-old ewes were used in this study. Animals were sacrificed at 3, 6, and 12 months. One animal entered a very prolonged followup and was sacrificed 2 years after surgery. Bone formation and scaffold resorption were evaluated by sequential x-ray studies, CT scans, histology, immunohistology, microradiography, and quantitative analysis of x-ray studies (optical density) and microradiographs (percentage of bone and scaffold area). Our data show an excellent implant integration and significant bone regeneration within the bone substitute over the course of the experiment. Progressive osteoclastic resorption of the biomaterial was also evident. At 1 year from surgery, the remaining scaffold was approximately 10-20% of the scaffold initially implanted, while after 2 years it was essentially completely resorbed. At the end of the observation period, the segmental defect was filled with newly formed, highly mineralized, lamellar bone.

Variation of trabecular architecture in proximal femur of postmenopausal women.

This investigation of microstructure in the human proximal femur probes the relationship between the parameters of the FRAX index of fracture risk and the parameters of bone microstructure. The specificity of fracture sites at the proximal femur raises the question of whether trabecular parameters are site-specific during post-menopause, before occurrence of fragility fracture. The donated proximal femurs of sixteen post-menopausal women in the sixth and seventh decades of life, free of metabolic pathologies and therapeutic interventions that could have altered the bone tissue, constituted the material of the study. We assessed bone mineral density of the proximal femurs by dual energy X-ray absorptiometry and then sectioned the femurs through the center of the femoral head and along the femoral neck axis. For each proximal femur, morphometry of trabeculae was conducted on the plane of the section divided into conventional regions and sub-regions consistent with the previously identified trabecular families that provide regions of relatively homogeneous microstructure. Mean trabecular width and percent bone area were calculated at such sites. Our findings indicate that each of mean trabecular width and percent bone area vary within each proximal femur independently from each other, with dependence on site. Both trabecular parameters show significant differences between pairs of sites. We speculate that a high FRAX index at the hip corresponds to a reduced percent bone area among sites that gives a more homogeneous and less site-specific quality to the proximal femur. This phenomenon may render the local tissue less able to carry out the expected mechanical function.