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. (Journal of Applied Biomaterials & Biomechanics 2003; 1: 186-93).

Methods and applications of three-dimensional imaging in orthopedics.

Computed tomography is a commonly used technique for detecting pathological alterations in soft tissues and the skeleton. Three-dimensional images of the skeleton are very useful for planning surgical treatment and monitoring therapy, but unfortunately mental reconstruction of complex three-dimensional anatomical structures from conventional tomography is very difficult. This article describes a process by which automated analysis of the regions of interest in the computed tomographic (CT) images yields the contours of the surfaces which can be presented pseudo-three-dimensionally using Phong's lighting model and Gouraud's shading methods. Three applications in the areas of orthopedics and neurosurgery demonstrate the efficacy of the method.

Mass whitening of synthetic fibers and plastics.

The evaluation of new and improved techniques has led to the development of mass whitening methods for use with synthetic fibers and plastics. The processes are complex but well defined, and call for the use of sophisticated fluorescent whitening agents (FWAs) to meet the requirements of the fiber or plastics manufacturer, the textile finisher, and the end user. The performances of some leading commercial whiteners are compared and their interactions with dyes, fillers and stabilizers are discussed.