The relationship of the position of crown margins to gingival health.

A survey was conducted of 423 crown margins that were divided into 355 subgingival margins and 68 supragingival margins. The plaque index, gingival bleeding, and recession surrounding the artificial crown were recorded and compared to the unprepared contralateral tooth. Gingival tissues tended to bleed 2.42 times more frequently with subgingival margins and have a 2.65 times higher chance of gingival recession. Crowns with supragingival margins did not differ significantly compared with the contralateral tooth, but crowns with subgingival margins had greater bleeding and recession compared with the contralateral tooth. It is recommended that supragingival margins become standard clinical procedures when feasible. A further analysis will be instituted to determine whether different crown materials affect the gingivae.