الفهرس 
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Abstract
Background: Tooth fragment re-attachment represents an important technique in restoring fractured anterior teeth. The final esthetic appearance and the strength of the re-attached tooth are dependent partly on correct hydration of the fragment. Aim : Evaluate and compare the effect of different storage media of the tooth fragments on the color matching of the re-attached segment with the original tooth structure, on fracture resistance of re-attached teeth and on the mode of failure of re-attached fragments after one day, one week and two weeks storing time. Design of the study : A total number of 144 permanent incisor teeth were used. The fracturing procedure was done by a blunt chisel and hammer. The fractured fragments were then stored in appropriate storage media (dry, tap water, full humidity and milk) for one day, one week and two weeks. As scheduled, the fragments were re-attached using a flowable composite. After re-attachment of the fragments, standard photographs were captured for all teeth using a fixed film-object distance and magnification. Then, the photographs were assessed and the results were presented as percentages. All samples were subjected to fracture resistance test using a universal testing machine at a speed of 0.5 mm/min. The force required to fracture each tooth was recorded in Newton (N) and the data were collected and statistically analysed. The fractured edges of the teeth and fragments were examined under a stereomicroscope and the results were tabulated. Results: Fragments stored in dry environment demonstrated the highest color disharmony results even if the fragment kept for one day. One day fragment storing in milk and water was found to be with significantly higher fracture resistance than one and two weeks storing (P< 0.001). No significant differences were detected between the different media in one and two weeks storing. The mode of failure revealed the adhesive mode of fracture at the re-attachment line in all groups. Conclusion: Hydration and dryness avoidance are of fundamental importance for the maintenance of the original aesthetic appearance of the tooth. Keeping the tooth fragment wet in milk or water for one day yields the highest fracture resistance.