In conclusion, both collagen and ePTFE barriers proved suitable for achieving GBR of osseous defects surrounding dental implants. The results of this study stress the importance of barrier fixation at the time of initial surgery.

The present results support the role of electrostatic interaction in adhesion, and introduce an effective method of reducing adhesion of C. albicans to PMMA surfaces through modification of the surface charge of polymeric biomaterials.

Patch clamp physiological techniques were used to characterize the voltage-activated calcium currents (VACC) expressed in the plasma membrane of osteoblastic cells as a function of time in culture and proliferative state of the cell. Osteoblast-enriched preparations were isolated by collagenase digestions of newborn rat calvaria and cultured under different conditions which affected cell proliferation (i.e., low serum in the media to arrest proliferation). VACC were isolated by replacing the intracellular potassium with cesium, and adding 1 microM tetrodotoxin to the bath. Under conditions that favored cell proliferation, low cell density, and media supplemented with 10% fetal calf serum (FCS), a transient calcium current was not expressed until day 3 in culture. There was a statistically significant relationship between the percentage of cells expressing this current and the time in culture. The magnitude of the current significantly increased as days in culture increased. Under the same conditions, the sustained VACC was detected after 7 or 8 days in culture. However, arresting cell proliferation after 2 days in culture by reducing the FCS concentration to 0.01% induced the expression of the sustained VACC the next day. The data suggest that the expression of VACC in the plasma membrane of rat calvarial osteoblasts depends on the time in culture and the state of proliferation of the cells. These results should prove to be valuable in studying the functional significance of VACC in osteoblastic cells and their regulation by various bone regulatory agents.

No abstract

The electronically guided alignment device (EGAD) has been demonstrated to function well with a custom fabricated stent for taking radiographs for subtraction. The objective of this study is to demonstrate that this device functions well when used with an impression bite-block rather than a full arch acrylic stent. Nineteen subjects participated. Two vinyl siloxane impressions were made for each subject and a pair of x-rays was taken with each impression. The location for study was divided among 7 for the maxillary premolar-1st molar region, 6 for the mandibular premolar-1st molar region, and 6 for the incisor-canine region. To simulate bone change 3 bone chips (approximately 1, 7, and 10 mg) were positioned in the mucobuccal fold when one of each pair of x-rays was taken. Pairs of radiographs were subtracted and the bone change (chips) isolated by thresholding to determine their area. An aluminum ramp was used to determine volume. A strong linear relationship between actual chip weight and equivalent aluminum volume (r2 = 0.64, P < 0.001) was obtained for all regions of the mouth when considered together. The strongest relationship of the 3 regions was for mandibular premolar-1st molar sites, r2 = 0.78. These data indicate that the EGAD/impression technique is suitable for taking radiographs in all areas of the mouth for quantitative digital subtraction.