How much space should there be between the crown margin and the finish line of a preparation?

The ideal space between the crown margin and the finish line of a preparation is 0.5 mm. This spacing ensures that there is sufficient room for the dental material to flow and adequately adapt to the tooth structure, promoting a strong bond and minimizing the risk of gaps that could lead to microleakage or decay.

The 0.5 mm margin also allows the dental professional to achieve the proper contour and occlusion of the final restoration, making it essential for achieving aesthetic outcomes and functional effectiveness. This spacing supports flexibility in material choice, whether using metals, ceramics, or composites, and enhances the overall success of the crown placement.

Other spacing options either provide too much or too little room for the crown margin, which could adversely affect the quality and longevity of the restoration. Thus, 0.5 mm is recognized as the optimal measurement in clinical practice.