RESUMEN
In this report the protective effect of acetyl salicylic acid [ASA] against radiation injury to salivary glands in rats was assessed. Thirty male rats were used in this study and classified as two groups. The control group didn't receive ASA throughout the experiment. While the experimental group received ASA in drinking water [2.5g/ 1L] one week before the exposure to irradiation. Both groups were irradiated by single dose gamma radiation [6.5Gy]. The administration of ASA to the experimental group was continued up to five weeks after radiation. The parotid and submandibular salivary glands were excised and prepared for histological and histochemical examination. The prepared sections were either stained with Haematoxylin and Eosin for routine histological examination, while others were stained by silver staining for detection of Nucleolar Organizer Region [AgNORs] at one and five weeks only. Our data revealed remarkable reduction in the damaged effect of irradiation in the experimental group of both glands along all period of the experiment following irradiation. Furthermore, the regeneration rate of destructive parenchymal elements was found to be faster in the experimental group than in the control group. By employing silver staining to detect the nucleolar organizer region, our results reported that the survival cells were stained brown. Comparing the whole results, it was obvious that the percentage of survival cells were higher in the parotid gland than in the submandibular gland. Furthermore the experimental group of both glands showed significant increase in the survival cells as well as in their distribution compared to that observed in the control group both after one and five weeks following irradiation. Finally the protective effect of ASA reflected on the higher percentage of survival cells in the experimental group in both glands. This could be explained on the assumption that ASA produced a concentration dependent reduction in radiation induced DNA damage in the cells
RESUMEN
In the present study, some mechanical properties namely; diametral tensile strength, abrasion wear resistance and hardness of six different tooth-coloured restorative materials were investigated. These aesthetic restorative materials were exposed to a dose of y-radiation similar to that used in radiotherapy of the neoplasms of the head and neck [60 Gy]. An assumption was suggested that ionizing radiation would affect the mechanical properties of these materials. The investigated materials were of different formulation [conventional chemically cured composite, light cured composite, compomer, Ormocer, conventional glass ionomer and polyacid modified glass ionomer]. A total of 180 samples were prepared in split Teflon mould having 5 holes of 3 mm diameter and 6 mm thickness each. Half of the specimens were irradiated by y-radiation in Indian gamma chamber [[6]Co] installed in National Center for Radiation Research and Technology [NCRRT]. Both unirradiated and irradiated samples were divided into 6 groups, 15 samples each, according to the materials used in their preparation and then were further subdivided into 3 sub groups of 5 specimens each to be tested mechanically. The diametral compression test was performed using Instron Universal testing machine at cross head speed 0.5 mm/min. The wear rate was driven by calculating the weight loss using AP 40 abrasive testing machine while hardness was carried out using Vicker's microhardness tester. Spectrophotometric analysis [FTIR] was run at ab-sorbance unit 2000-500 cm[-1] for all the tested materials before and after radiation to trace any structural changes. The results showed an enhancement in diametral tensile strength for all tested materials except for Ormocer which showed significant reduction of its strength after y-radiation. Although wear resistance of all polymeric-based materials are improved insignificantly and significantly for light cured composite, glass ionomer - based materials showed high significant reduction of wear resistance at level of confidence a = 0.001. On the other hand, y-radiation had detrimental effect on the hardness of polymeric based materials but glass ionomer based materials had insignificant increase of their hardness. Within the context of this study, the coloured - tooth restorative materials can be used satisfactorily in conservative treatment of patients who would receiving radiotherapy. Moreover, some of these materials are fluoride releasing, so further investigations were suggested because they would be beneficial preventive measure as oral fluoride application is essential after radiotherapy
RESUMEN
Prosthetic rehabilitation of patients under going hemodialysis of chronic renal failure poses special challenge to the prosthodontist. This could he attributed to the bony changes and muscle weakness that may accompany this disease
Aim: The present study was undertaken to evaluate the effect of prosthetic rehabilitation of these patients on muscle activity and bone density
Material and Methods: Five patients with mandibular bilateral free end saddle were selected from those undergoing hemodialysis. Partial denture was made for each patient. Electromyographic evaluation of both masseter and anterior fibers of temporalis were recorded during clenching, chewing soft and hard food immediately and after three month of denture insertion. Computer assisted densiometric was also performed at one, three and six month after denture insertion
Result: The masseter muscle during all function showed highly significant increase compared to the temporalis muscle. EMG at clenching of teeth was higher than chewing hard food that showed higher activity than during chewing soft food. The bone density showed reduction at all the study intervals. A significant difference was found between three and six month and highly significant decrease was shown between one and six month after denture insertion [p<0.01]
Conclusion: Based on our observation, it could be concluded that prosthetic rehabilitation of chronic renal failure patients showed reduction of both muscle activity and bone density after denture insertion