What & why:
Simple interrupted dermal sutures (more commonly referred to as deep dermal sutures) are sutures placed within the dermal layer to reduce the static tension on a gaping wound.
In contrast to the epidermal layer, where you will most often be using non-absorbable suture material like nylon, the dermal layer should be closed with absorbable sutures since you won’t be able to remove them later. Ideally, a suture material with minimal tissue reactivity but a longer period of effective wound support is best. I typically use polyglactin (vicryl) or braided lactomer (polysorb) sutures for this purpose. Size 3-0 or 4-0 is generally appropriate depending on the body location and how much tensile strength is needed.
More sophisticated alternatives exist for a deep suture layer, such as the set-back dermal suture. However for the novice practitioner, the deep dermal simple interrupted is the first stop in learning to manage more complex wounds.