Linked to marginal integrity, placement of the finish line can directly affect the ease of manufacturing the crown and health of the periodontium.
Best results are achieved where the finish line is above the gum line as this is fully cleanable.
They should also be placed on enamel as this creates a better seal.
Where circumstances require the margins to be below the gum line, caution is required as several problems can arise.
First, there might be issues in terms of capturing the margin when making impressions during the manufacturing process leading to inaccuracies.
Secondly, the biologic width, the mandatory distance (roughly 2 mm) to be left between the height of the alveolar bone and the margin of the restoration; if this distance is violated, it can result in gingival inflammation with pocket formation, gingival recession and loss of alveolar bone crest height.
In these cases, crown lengthening surgery should be considered.
Linked to marginal integrity, placement of the finish line can directly affect the ease of manufacturing the crown and health of the periodontium. Best results are achieved where the finish line is above the gum line as this is fully cleanable. They should also be placed on enamel as this creates a better seal. Where circumstances require the margins to be below the gum line, caution is required as several problems can arise. First, there might be issues in terms of capturing the margin when making impressions during the manufacturing process leading to inaccuracies. Secondly, the biologic width, the mandatory distance (roughly 2 mm) to be left between the height of the alveolar bone and the margin of the restoration; if this distance is violated, it can result in gingival inflammation with pocket formation, gingival recession and loss of alveolar bone crest height. In these cases, crown lengthening surgery should be considered.
Crown (dentistry)