When additional retention and resistance is needed in a dental restoration, which margin location is required?

Choosing a subgingival margin location for dental restorations can significantly enhance retention and resistance. The subgingival margin is positioned below the gum line, providing an area where the restoration can engage more tooth structure, which is particularly beneficial when additional support is necessary. This margin allows for better mechanical retention, as it can be designed in a way that engages the natural contours of the tooth and minimizes the risk of dislodgment during chewing or other functional stresses.

Moreover, subgingival margins can improve the seal against bacteria and can be advantageous in cases where there is a risk of microleakage, thereby contributing to improved longevity of the restoration. The utilization of dental materials that bond well to the tooth structure at this level can also further enhance retention.

In situations where greater resistance to displacement is critical—such as with large restorations, situations involving significant occlusal forces, or when there may be a lack of remaining tooth structure—the subgingival approach can be particularly warranted. This is in contrast to supragingival margins, which may not provide the same level of engagement with the tooth and therefore may be less effective in situations requiring increased retention and resistance.