Due to the small number and the limitations of the included studies the results do not provide conclusive evidence as to the effect of prosthetic margin placement on the incidence of secondary caries
Effect of posterior crown margin placement on gingival health.
STATEMENT OF PROBLEM The clinical impact of  posterior crown margin placement on gingival health has not been thoroughly quantified . PURPOSE This study evaluated the effect of posterior crown margin placement with multivariate analysis . MATERIAL AND METHODS Ten general dentists review ed 240 patients with 480 metal-ceramic crowns in a prospect i ve clinical trial . The alloy was r and omly selected from 2 high gold , 1 low gold , and 1 palladium alloy . Variables were the alloy used , oral hygiene index score before treatment , location of crown margins at baseline , and plaque index and sulcus bleeding index scores recorded for restored and control teeth after 1 year . The effect of crown margin placement on sulcular bleeding and plaque accumulation was analyzed with regression models ( P<.05 ) . RESULTS The probability of plaque at 1 year increased with increasing oral hygiene index score before treatment . The lingual surfaces demonstrated the highest probability of plaque . The risk of bleeding at intrasulcular posterior crown margins was approximately twice that at supragingival margins . Poor oral hygiene before treatment and plaque also were associated with sulcular bleeding . Facial sites exhibited a lower probability of sulcular bleeding than lingual surfaces . Type of alloy did not influence sulcular bleeding . CONCLUSION In this study , placement of crown margins was one of several parameters that affected gingival health
Due to the small number and the limitations of the included studies the results do not provide conclusive evidence as to the effect of prosthetic margin placement on the incidence of secondary caries