Objectives: The purpose of this study was to examine the ability of a CAD/CAM machine (CEREC Scan) and a composite material to produce a bevel finishing line which will allow the preparation of more conservative designs. Materials and Methods: For the purpose of this study a brass mould was prepared with a different finishing line circumferentially. Namely a 90° shoulder was prepared mesially which was reduced gradually to 30° bevel lingually, 60° bevel distally and 30° bevel buccaly. A duplicate model of the brass model was scanned with the help of CEREC Scan^TM (Sirona). A crown restoration was designed using the Cerec3 software and fifteen crowns were milled using Paradigm MZ100^TM (3M/ESPE). Each crown was cemented onto the original brass model with a light body silicon material (Express, 3M/ESPE) under a standardised loading condition (40N, 5min). The crowns, with the set silicon polymer film still attached, were removed from the brass model. The silicon film was detached from the crowns using a contrasting impression material. Buccal-lingual and mesial-distal sections of the silicon impressions were produced and the marginal gaps of the crowns were measured using a travelling microscope at x30 magnification. Results: The average marginal gap for each point was: Buccal (30°): 86±21 µm, Mesial (90°): 94±18µm, Lingual (30°): 88±34µm, Distal (60°): 84±23µm. One-way ANOVA analysis showed that the results were not statistically different. Conclusions: The marginal fit of Paradigm MZ100^TM resin composite crowns was within the range of clinical acceptance. Acknowledgements: We are grateful to 3M/ESPE for the donation of the resin composite blocks and the impression materials.

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