الفهرس 
AcknowledgementOnly 14 pages are availabe for public view
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Abstract
The present study was done to evaluate the histopathological changes that might occur in the dental pulp of the dog anterior teeth after bleaching using two in office bleaching systems utilizing light (Zoom) and chemical activation Opalescence Boost. It was found that after one day of bleaching using zoom system, the examined pulp showed highly dilated blood vessels engorged with red blood cells together with the presence of free extravasated erythrocytes. Some of the odontoblasts towards labial side of the bleached teeth showed degeneration and vacuolization. No signs of inflammatory cells infiltrate were observed. On the other hand, teeth which were bleached with Opalescence after the same period of time showed same results like that of the Zoom group but with exaggerated form. After 14 days of zoom bleaching, the examined pulp appeared similar to that of the control teeth. While for the teeth bleached with Opalescence Boost Whitening systems pulp tissue did not completely resume back to its normal histological picture. There was a considerable amount of fibroblasts and fibrous tissue. Slight vasodilatation of the blood vessels, vacoulation and edema were still present. However the rest of the pulp tissue exhibited histological characteristics of normality. CONCLUSION: In conclusion it could be suggested that both Zoom and Opalescence Boost are both well tolerated with low incidence of sensitivity and no significant differences in the safety profile between groups.