RESUMEN
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
RESUMEN
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
RESUMEN
The objective of obturation in endodontic is total obliteration of the root canal system and development of a fluid-tight seal at the apical foramen. The aim of this work was to compare the apical seal of four root canal obturation techniques namely lateral condensation technique, vertical condensation technique, warm lateral condensation technique with an ultrasonically activated spreader and Thermafil, when used with two different root canals sealers. 80 extracted human maxillary anterior teeth were used in this study. All root canals were instrumented by the step back technique. Root were divided into four groups [according to the technique of obturation and each group was further subdivided into two subgroups according to the type of sealer used. Leakage evaluation was done by using clearance technique by maximum linear apical dye penetration. The results were tabulated and statistically analyzed. The obtained result showed that there was no significant difference among the four obturation techniques, regarding the apical leakage with insignificant difference between the two sealers. Vertical condensation is the most time consuming technique. Sealer extrusion occurs with all the specimens obturated by Thermafil. Clearing technique is a valuable method in evaluating apical leakage in extracted teeth
RESUMEN
Cytokeratins [CKs] are cytoskeletal intermediate filament proteins characteristic of odontogenic epithelia. The CK expression patterns of odontogenic epithelia are still poorly described. Most studies have searched for pools of CKs instead of individual polypeptides. The objective of this study was to clarify the immunohistochemical expression of individual CK polypeptides 14 in the enamel organ of rat molar at different developmental stages using monoclonal antibody LL002-Cks14. The results showed that all cells of the enamel organ were positive for CK14 and its configuration showed differences related to the stage-specific state of differentiation. A strong lablel for CK 14 was present at the inner dental epithelium at early bell stage, preameloblasts and amelobalsts. It is concluded that the monoclonal antibodies to CK 14 are well documented and should serve as useful tools for tracing the development and differentiation of ameloblasts. The developing enamel organ may be a suitable model for investigating the relationship between keratin expression and cell function
RESUMEN
This study was undertaken to evaluate the differences between healthy and periodontally diseased root cementum including distribution of various elements within cementum, presence of endotoxins and surface characteristics of diseased cementum using light microscope, scanning electron microscope and electron dispersive x ray microanalysis. The results of this study showed that the inorganic content of the diseased cementum surface were altered and the cementum surfaces were generally rough, irregular covered by bacterial dental plaque displaying multiple deep resorption areas filled with bacterial endotoxins. According to this present work, efforts to restore the biocompatibility of the periodontitis-affected root surface by removal of the superficial and weakly attached plaque may be the goal of the periodontal therapy, instead of the total removal of the periodontally involved cementum
RESUMEN
This study was designed to clarify the effects of systemic administration of bisphosphonate, pamidronate, on the bone resorbing activity of osteoclasts during relapse of rat molars, after experimental movement. The Waldo method was used on 24 rats to induce mesial movement of the maxillary first molars. An elastic band was inserted between the upper first and second molars of 7-week-old rats and removed 21 days later. At 1 day before elastic band removal, bisphosphonate . was administered via a tail vein. After elastic band removal, the rats were further maintained for 0, 5, or 10 days. The relapse of the first molars was studied by means of light and scanning-electron and transmission-electron microscopy. Administration of bisphosphonate significantly decreases the relapse of moved teeth to their original positions. In bisphosphonate-treated rats, osteoclasts aggregated in a fewer and smaller number along the alveolar bone surfaces facing the periodontal ligament and also induced structural changes in osteoclasts, such as disappearance of ruffled borders and cytoplasmic polarity These results suggest that a single systemic administration of bisphosphonate decreases the extent of initial relapse in experimentally moved rat molars via a mechanism involving impairment of the structure and resorptive functions of osteoclasts
RESUMEN
The experimental study of the effect of low power laser irradiation [LPLR] on nerve injury histologically and histochemically had been carried out. Ten dogs were used in this study and divided into two groups, control and experimental. Surgical exposure of their mental nerves was done for all in the same way. In the experimental group, the exposed nerve was subjected to laser irradiation for 5 minutes following the application chart of the device for neural disorders, and then the animals were scarified at 1, 3. 7, 14, 30 days intervals. The control group were followed the same regime but without laser radiation. Biopsies were taken for light microscopy study [H and E and silver impregnation stain], electron microscopy study and histochemical study [OTAN and Gomori's acetyl thioccholine methods] was used. The obtained results were as follow: Temporary mild 'degenerated traumatic changes occurred at the first, third and seventh day following laser radiation. Regeneration started at 14[th] day with complete regeneration at 30[th] day. It can be concluded that laser therapy enhance recovery of injured irradiated nerve without any residual effects