ABSTRACT
Chromium is an essential trace element whose physiological role is related primarily to the maintenance of normal glucose tolerance, because it serves as a cofactor for the peripheral action of insulin. It is present in the environment in several different forms including chromium [0], chromium [III], and chromium [VI]. Hexavalent chromium [Cr VI] is thought to be the most toxic of the released metal ions. This study was done to evaluate such toxic effect on rat lingual papillae and the curative effect of vitamin E on the induced structural changes using light and electron microscopy. The results showed that chromium induced degenerative changes with the lingual papillae especially the filiform, which can be countered by vitamin E supplementation having an antitoxic effect which advocate re-epithelization and regeneration of the connective tissues
ABSTRACT
The purpose of this work was to study the structure and thickness of the prismless layer in deciduous molars and to evaluate the effect of different acid concentrations and different etching times on this prismless enamel. The teeth were examined with polarized light and scanning electron microscope. The surface enamel shows a more negative birefringence in contrast to the underlying enamel. The prismless enamel was categorized into false, moderate, essential and complex types according to whether they took the form of distinct prisms which bound at the subsurface, indistinct or circularly based prisms or not. 10% phosphoric acid gel for 15 or 45 seconds did not produce suitable morphological changes for the purposes of retention or mechanical bonding of resins, while etching with 35% for 15 and 45 seconds produce a significant etching patterns suitable for resin bonding with complete removal of the prismless layer
ABSTRACT
Immediate implants are widely used nowadays in an attempt to reduce post-extraction alveolar bone resorption associated with delayed implantation. Nevertheless, due to discrepancy between the transversal diameters of the socket and of the implant, a gap may generate between the bony walls of the socket and the neck of the implant. Simvastatin, a cholesterol lowering drug, is used systemically in treatment of osteoporosis due to its demonstrated bone forming potential. In the current work, the studied drug was formulated as granules in cellulosic polymeric matrix [Hydroxy propyl methyl cellulose HPMC] in Faculty of Pharmacy, Alexandria University to be used locally around immediate implants. Eight dogs in the present study were used to evaluate clinically and histologically the effect of local application of Simvastatin granules around immediate implants. A split mouth design was used. In all dogs, under general anesthesia, flaps were reflected and extraction of left and right mandibular third premolars was surgically and atraumatically performed. The right side of the mandible was considered as the study group, where acid-etched, sand-blasted, large grit Microdent implants [3.5 mm in diameter; 10 mm long] were immediately seated around with Simvastatin granules [2.2mg] were packed; whereas the left side of the mandible constituted the control group where only implants were placed. Four dogs were sacrificed at 3 weeks, and the remaining four were euthanized at 3 months. The animals were clinically evaluated the day of sacrifice for gingival color and bleeding. After decalcification, the implants were removed and specimens were processed and stained with H and E and Gomori's Trichrome stains. Histologic evaluation was performed for determination of type of healing, and tissue reaction in both groups. All cases showed uneventful clinical healing without signs of infection, but the study group manifested better and faster healing as regards the gingival colour and bleeding. Histological results were favourable in both groups, with better findings in Simvastatin filled defects where bone regeneration was evident from host bone to implant site; neo-vascularization and absence of inflammatory cells were also apparent in this group. It could be concluded that Simvastatin granules around immediate implants results in osteogenesis filling the space around the implants more preferably than control group. Moreover, Simvastatin could be an alternative to guided bone regeneration
ABSTRACT
The present study was performed to evaluate the histological reaction of two graft materials both are widely used clinically Demineralized freeze-drired bone [DFDBA] and Medpor on bone. They are different in chemical and physical composition. 15 rabbits [males] were used in this study. Osseous defects were created in the buccal side of their mandibles. Then the animals were divided into 3groups: group I [control], group II [study] that included osseous defects filled with DFDBA, group III [study] which included osseous defects filled with Medpor. The experimental animals were sacrificed in intervals 2,6,12 weeks. Histological and histochemical results revealed: successful bone healing in all groups. DFDBA group showed a number of inflammatory cell at the area of osseous defect after 2 weeks. Followed by formation of woven bone between the bone graft material then progressive bone formation, maturation and regeneration were observed. The mature bone was greater in amount than the two orther groups, fused completely to the host bone. The DFDBA was completely resorbed by the end of the experiment. The Med por group showed few inflammatory cells in 2 weeks then new bone formation and fibrous tissue in growth between its pores were observed together with areas of fusion to the host bone. By the end of the follow up period dense mature bone trabeculae attached to the Med por particles were forming a dense mass fused completely to the host bone. The control group showed normal bone healing less in amount than the DFDB group and less indense than the Med por group. Alkaline phosphatase enzyme activity was increased with the period of follow up marked on the surface of the host bone facing the graft materials and on the bony trabeculae between the materials particles of the both DFDB and Med por