This is a real-world medical entrance exam question, please give the true answer based on the question and selection. Topic name: None, Subject name: Dental
When deep gingival extension of proximal box is anticipated, which  of the following is used? 
Select and explain. 
A. Round toothpick wedge, B. Triangular wedge, C. Elliot’s separator, D. Kesling separator
B: Triangular wedge
Answer: B: Triangular wedge 
Explanation: To protect the gingiva and the rubber dam when extending the gingival wall apically, a wooden wedge should already be in place in the gingival embrasure to depress soft tissue and the rubber dam. A round toothpick wedge is preferred unless a deep gingival extension is anticipated. A triangular (i.e., anatomic) wedge is more appropriate for deep gingival extensions because the greatest cross-sectional dimension of the wedge is at its base; as the gingival wall is cut, the bur’s end corner may shave the wedge slightly.