Marginal staining is a long-term problem with porcelain veneers and is most apparent at the proximal margins. The current trend in veneer preparation is to extend the preparation through the interproximal contacts except for the distal aspect of the canines. What can be stated about this?

The assertion regarding marginal staining being a long-term problem with porcelain veneers, particularly at the proximal margins, is accurate. This staining can occur due to plaque accumulation and the inability of the materials to completely seal the margins, leading to a breakdown of the interface between the veneer and the tooth structure over time. This is a recognized concern in aesthetic dentistry, hence the emphasis on ensuring good marginal integrity.

Regarding the trend in veneer preparation, it is indeed becoming more common to extend the preparation through the interproximal contacts, with the exception of the distal side of the canine teeth. This approach allows for better adaptability and positioning of the veneers, which can enhance the esthetic result and minimize the risk of marginal staining. By extending the preparation, it creates a more consistent surface for bonding and can better achieve a natural appearance.

Therefore, both statements reflect current practices and concerns in the field of dentistry, confirming their truth. The understanding of these trends and issues is critical for effective veneer placement and long-term aesthetics, making option A the correct choice.