Periodontal response to two different subgingival restorative margin designs: a 12-month randomized clinical trial

Subgingival margin placement is sometimes required due to different reasons and is often associated with adverse periodontal reactions. The purpose of this study was to determine if a single restoration with subgingival margin on a tooth, in the maxillary anterior zone, would affect its periodontal soft tissue parameters, and whether or not a deep chamfer preparation has a different influence in the periodontium when compared to a feather edge preparation.

Plaque and gingival indexes, periodontal probing depth, bleeding on probing, and patient's biotype were registered. One hundred six teeth were prepared with a deep chamfer, while 94 were prepared with a feather edge finishing line. Twelve months after the restoration delivery, the same parameters were evaluated. Repeated measure one-way analysis of variance (ANOVA) (α = 0.05) was used.

A statistically significant difference between the baseline and the 12-month follow-up is present in regard to plaque index, gingival index, and periodontal probing depth, but no statistically significant difference between chamfer and feather edge finishing lines. There is a statistically significant difference between the baseline and the 12-month follow-up in regard to bleeding on probing. Feather edge preparation presents significantly more bleeding on probing and less gingival recession than the chamfer.

Subgingival margins do influence the periodontal soft tissue response. Statistically significant difference exists between feather edge and chamfer finishing lines in regard to bleeding on probing and gingival recession.

Subgingival margins should be carefully selected, especially when feather edge finishing line is utilized.