Wound dehiscences after lower third molar surgery potentially extend the time of postsurgical treatment and may cause long-lasting pain. It was the aim of this prospective study to evaluate the primary wound healing of 2 different flap designs. Sixty completely covered lower third molars were removed. In 30 cases, the classic envelope flap with a sulcular incision from the first to the second molar and a distal relieving incision to the mandibular ramus was used, whereas the other 30 third molars were extracted after preparation of a modified triangular flap first similarly described by Szmyd. Wound healing was controlled on the first postoperative day, as well as 1 and 2 weeks after surgery. The overall result was a total of 33% wound dehiscence. In the envelope-flap group, wound dehiscences developed in 57% of the cases. This represents a relative risk ratio of 5.67, with a 95% CI from 1.852 to 12.336. With the modified triangular-flap technique, only 10% of the wounds gaped during wound healing. This study confirms evidence that the flap design in lower third molar surgery considerably influences primary wound healing. The modified triangular flap is significantly less conducive to the development of wound dehiscence.