Effect of crown margins on periodontal conditions in regularly attending patients.

Subgingival margins of cast restorations have been associated with increased gingival inflammation and probing depth, but it is not known if such effects would be seen among patients receiving regular professional care. In this study, 831 regularly attending patients in 35 North Carolina dental practices were examined. Plaque, gingival inflammation, calculus, and probing depth were assessed on facial and mesiofacial surfaces of the Ramfjord teeth. Surface-specific analyses showed significantly greater (p less than 0.05) gingival inflammation and deeper probing depths with subgingival cast restoration margins for nearly all surfaces examined. Less frequently, decreases in plaque and calculus were associated with the presence of crowns. Intact surfaces in patients with cast restorations were not significantly different from the same surfaces in patients without cast restorations. Even among patients receiving regular preventive dental care, subgingival margins are associated with unfavorable periodontal reactions.