Which recommendation is NOT appropriate for all ceramic inlay/onlay preparations?

The statement regarding the central groove reduction following unprepared tooth anatomy is not appropriate for all ceramic inlay/onlay preparations. In restorative dentistry, particularly with ceramic materials, the design and preparation of the cavity must take into account factors such as occlusion, the bonding characteristics of the ceramic, and the structural integrity of the restoration.

When preparing for an all-ceramic inlay or onlay, the central groove may require adjustments that go beyond simply mimicking the unprepared tooth anatomy. The goal is to create a restoration that not only fits into the space but also optimizes function and longevity. It's essential to consider the overall design, including the need for proper clearance and occlusal contacts, when executing such preparations.

The other recommendations provided are essential for effective all-ceramic restorations. Avoiding centric contact points for margin placement ensures that there is less stress on the restoration during function, thereby preventing premature failure. Adequate clearance is crucial; onlays require sufficient thickness to withstand occlusal forces without fracturing while maintaining esthetics. Lastly, bevels are typically contraindicated for all-ceramic restorations because they can compromise the bonding surface and overall strength of the material.