Advantages of porcelain veneers versus direct composite veneers include all of the following except one. Which is the exception?

Porcelain veneers offer several advantages over direct composite veneers, particularly in the context of aesthetic results and durability. One of the key benefits is their longevity. Porcelain is generally more durable and resistant to staining compared to composite materials, which can become discolored over time. This makes porcelain veneers a favorable option for patients seeking a long-lasting solution for cosmetic dental issues.

Another advantage is that porcelain veneers are less sensitive to operator technique. The process of placing porcelain veneers is typically more forgiving regarding the accuracy and precision of the dental professional's work. This characteristic allows for better overall results, even if the application technique is not perfect.

However, the statement regarding the need for multiple appointments reflects a common characteristic of porcelain veneer placement. Typically, the process requires an initial appointment for tooth preparation and impression taking, followed by a second appointment for placement after the fabricating of the veneers in a dental lab. This is contrasted with direct composite veneers, which can often be completed in a single visit, making them more expeditious in terms of placement.

Thus, the exception in this context is indeed related to the requirement of multiple appointments for porcelain veneers compared to the more immediate nature of composite veneer application.