الفهرس | Only 14 pages are availabe for public view |
Abstract Several studies have shown that nicotine may be one of the most significant risk factors for the development and progression of periodontal disease. Smoking is a predisposing factor for periodontal diseases and gingival recession )Darby and Walsh , 2003). To overcome the effects of nicotine on the PDL there are many stratigies, one of them is the smoking cessation. The other is the use of antioxidants that eliminate prooxidants and scavenge free radicals. The water-soluble antioxidant vitamin C can reduce free radicals directly or indirectly (Sies et al., 1992). Materials and methods: 77 adult male albino rats were used in this study. The rats were divided into the following groups: 1. Control Group: 28 rats that were injected intraperitoneally with 0.2 ml distilled water once daily for 2 weeks. The rats of this group were equally subdivided into 4 subgroups (7 rats each) according to time of scarification as follows: Subgroup C 1: sacrificed 1 day after the last injection. Subgroup C 7: sacrificed 7 days after the last injection. Subgroup C 14: sacrificed 14 days after the last injection. Subgroup C28: sacrificed 28 days after the last injection. 2. Nicotine positive control Group (NC): Consisted of 7 rats each rat was injected intraperitoneally with nicotine hemi-sulfate (N.H.S.) aqueous solution with a dose of 3.0 milligrams per kilogram (mg/kg) of body weight once daily for two weeks. The rats of this group were sacrificed 1 day after the last nicotine injection. 3. Experimental cessation group:(E) Consisted of 21 rats each rat was injected intraperitoneally with N.H.S. aqueous solution with a dose of 3.0 mg/kg of body weight once daily for 2 weeks. The rats of this group were subdivided into 3 subgroups (each consisted of 7 rats) according to time of scarification after the nicotine injection has been stopped as follows: Group E 7: sacrificed 7 days after the last nicotine injection. Group E 14: sacrificed 41 days after the last nicotine injection. Group E 28: sacrificed 28 days after the last nicotine injection. 4. Experimental cessation plus vitamin C group:(EV) Consisted of 21 rats each rat was injected intraperitoneally with N.H.S. aqueous solution with a dose of 3.0 mg/kg of body weight once daily for 2 weeks. On last day of nicotine injection, rats were concomitantly start daily receiving vitamin C and the nicotine injection was stopped. The rats of this group were subdivided into 3 subgroups (each consisted of 7 rats) according to time of scarification as follows: Group Ec 7: sacrificed after 7 days of vitamin administration. Group Ec 14: sacrificed after 14 days of vitamin administration. Group Ec 28: sacrificed after 28 days of vitamin administration. Preparation of specimens for histological study The Mandibular molar areas were excised and were decalcified and processed for Haematoxylin and Eosin (H&E) staining and immunohistochemical stainin. Results: The examination of the H& E in stained sections of the control group showed that all the subgroups were of almost similar results. The PDL principal fibers were densely packed and were arranged in conveniently demonstrated groups: gingival, interdental and alveolodental. In all of the above groups, there was no aggregation of inflammatory cell infiltrate, no signs of degenerated fibers or excessive resorption in cementum or alveolar bone. Nicotine control group (NC) revealed several alterations in many of the structural criteria of the PDL. Wide spaces between bundles of fibers which were irregularly arranged if compared to the control group. The oblique fibers revealed detachment of the PDL fibers from the cementum and aggregation of inflammatory cells in proximity to these detached fibers. There were some osteoclastic activities. E7 group revealed minute changes from the nicotine control group. The arrangement of the fibers in this group was more dense and regular in comparison to the nicotine control group. The oblique group of fibers showed an enhancement in the attachment to the cementum. Group E14 showed a little improvement in comparison to group E7 regarding the attachment of the fibers to cementum and bone as well as the fiber regularity. On the other hand, group E28 showed further enhancement in the fiber remodeling and orientation as well as the resorption sites. Examination of EV 7 group revealed some improvement in the histological features when compared with both the nicotine control group and the group E7. The fibers were denser, with fewer voids observed, as well as they were attached to cementum to some extent but still the attachment is not as in control group. Some spacing voids were seen in some samples. The apical fibers of group EV7 showed almost a similar histological picture as group C. The interradicular group appeared almost normal except for minute detachment of the fibers from the cementum. The groups EV14 showed more improved histological features with minute defects regarding the fiber orientation, attachment and density. Group EV28 showed histological features almost similar to control group except for minute detachment of the PDL fibers in scattered regions. |