When placing intracrevicular margins, which statement is NOT a rule to follow?

The option indicating that all the above statements are correct is valid because each statement accurately reflects considerations when placing intracrevicular margins.

When establishing intracrevicular margins, it is crucial to position the margin appropriately in relation to the gingival crest and sulcus depth. The first point emphasizes maintaining a margin 0.5mm below the gingival crest for sulci that measure 1.5mm or less, which allows for adequate retention of the restoration and minimizes potential irritation to the surrounding tissues. The second point advises that if the sulcus depth exceeds 1.5mm, positioning the margin at half the sulcus depth ensures that the restoration fits comfortably without encroaching too deeply into the tissues, thus promoting optimal health and healing.

The third statement concerning evaluating for a gingivectomy with a sulcus that measures greater than 2mm is also important, as deeper sulci can indicate the presence of periodontal issues that may need surgical intervention to achieve proper marginal placement and overall health of the periodontal environment.

In summary, all these rules are established guidelines that help dental professionals in achieving successful restorative outcomes while maintaining periodontal health, reinforcing why the indication that all statements are correct is accurate.