Pellagra

The results of this study indicate that dental implants designed for a submerged implantation procedure can be used in a single-stage procedure and may be as predictable as one-stage implants. Although one-stage implant systems and two-stage.

Mucosal and radiographic aspects during the healing period of implants placed in a one-stage procedure

Purpose: The aim of this prospective clinical trial was to compare peri-implant clinical and radiographic parameters following the placement of nonsubmerged two- and one-stage implants. Materials and Methods: Patients were randomly assigned to the IMZ group (20 patients receiving two IMZ two-stage implants in a one-stage procedure) or ITI group (20 patients receiving two ITI implants in the conventional one-stage procedure). The healing period was defined as an 18-week unloaded osseointegration period and a 1-year functional period during which maturation of bone took place. Twelve weeks after implant placement, fabrication of an overdenture with a bar-clip attachment system was started; it was placed at 18 weeks. Results: None of the implants were lost during the osseointegration period; one IMZ implant was removed during the functional period because of mobility. There was no significant difference in Gingival Index between the two groups at all evaluation periods. The mean bone loss during the functional period was 0.6 mm in both groups. A high number of healing abutments loosened in the IMZ group. Conclusion: Clinical and radiographic parameters of two-stage implants placed in a one-stage procedure and one-stage implants are comparable during the healing period. Healing abutments of the IMZ implant system loosen easily

Mechanical properties of polystyrene-ethylene-propylene copolymer blends

Some mechanical properties of blends of polystyrene (PS) and ethylene-propylene-rubber (EP) were derived from stress-strain and impact measurements. The strength and impact properties are improved by adding EP-g-PS graftcopolymer, prepared by reacting PS with EP, to the blends. It is assumed that the EP-g-PS graftcopolymer acts as an adhesive at the interface between the thermoplast and the rubber phases. The addition of the graftcopolymer reduces the dimensions of the dispersed rubber particles. High values of impact strength at reasonable values of tensile moduli could be reached by replacing EP for a smaller or larger part by EP-g-PS copolymer. These kinds of EP-modified PS blends had much higher impact values than those of comparable PS blends containing low density polyethylene (I dPE) and 1 dPE-g-PS graftcopoly mer or this graftcopolymer only. It seems attractive to ascribe these results to the noncrystallinity of the PE-g-PS as compared with the crystallinity of ldPE in ldPE and in ldPE-g-PS. However some caution seems recommendable as EP-modified PS fractures with microshear whereas, the PE-modified PS shows crazing