Mouse macrophage phagocytic activity was studied during ontogenetic development by comparing the abilities of infant and adult mouse macrophages to ingest opsonized particles via Fc gamma R, Fc mu R, or CR3. These studies were performed on resident, BCG-, and thioglycollate-stimulated peritoneal macrophages. The percent of ingestion and the index of maximal phagocytosis mediated via Fc gamma R is lower in infant than in adult mouse macrophages. However, the adherence mediated by Fc gamma R is similar to that seen with adult cells. Similar results were obtained when phagocytosis was mediated via Fc mu R or CR3, reaching adult levels during ontogenetic development. We also studied the age-dependent release of H2O2 by peritoneal cells before and after incubation with phorbol myristate acetate. Interestingly, the capacity of peritoneal cells from infant animals to generate H2O2 after BCG infection is similar to that observed in adult mice. Our results suggest that the adherence and phagocytosis mediated by Fc gamma R, although at lower levels than in adults, and the production of microbicidal H2O2 may be relevant for mouse survival during the first days of life.

Age Factors↗

PubMedDate not supplied

Finite element analysis of a three unit fixed partial denture cast with nickel-chromium alloy.

A two dimensional mathematical model was generated, representing a three unit fixed-fixed partial denture and its supporting structures. Second premolar and second molar were used as abutments with first molar as pontic. A load of 1 kg was applied to the occlusal surface of the casting. Stresses and displacement developed at various regions were analyzed with STAAD III/ISDS program. Maximum stresses were developed in the pontic and connectors with distal connector experiencing the maximum stresses. Stresses transmitted to the dentin were comparatively lower and more of compressive in nature. The underying bone experienced moderate amount of both compressive and tensile stresses but the displacement in this tissue were minimal compared to the rest.

Chromium Alloys↗

PubMedDate not supplied

Stress variations in recast Ni-Cr alloy--a finite element analysis.

A finite element analysis was carried out to analyse the stress variations in a mandibular posterior fixed partial denture (FPD), made of recast nickel-chromium alloy. A two dimensional finite element model was developed and then analysed with STAAD III/ISDS program with an occlusal load of 1 kg applied to the casting surface. The analysis revealed that the connectors experienced maximum stresses and the generated stress values decreased within the fixed partial denture made of recast Ni-Cr alloy. It seemed unlikely that FPD inspite of being made of recast alloy might fail before the other tissue components show signs of degeneration thus establishing the potential for recycling the Ni-Cr alloy in actual dental practice.

Bite Force↗