In terms of circumference, where is the smaller circumference placed when packing a cord?

The smaller circumference when packing a cord is placed at the gingival cervix. This area is located at the junction between the tooth and the gingiva (gum). When a cord is packed in this region, it helps create a better fit and facilitates the capture of the gingival margin during impressions.

Positioning the smaller circumference at the gingival cervix is critical because it allows for careful displacement of the gingiva without causing trauma. This approach ensures that the cord can achieve a tight seal at the cervical area, which is pivotal for obtaining an accurate impression of the tooth's contours and the surrounding soft tissue.

Other regions, such as the buccal surface, occlusal surface, and facial surface, are not ideal locations for placing the smaller circumference of a cord, as they do not provide the same benefits for impression accuracy or gingival health. The anatomical considerations of the gingival cervix make it the most suitable area for secure packing of the cord, thus enhancing the overall quality of the dental procedure.