Background: To evaluate the intensity of pain, swelling and trismus after the removal of impacted lower third molars comparing two different suture techniques of the triangular flap: the complete suture of the distal incision and relieving incision and the partial suture with only one suture knot for closure of the corner of the flap and the closure of the distal incision, without suturing the relieving incision. Material and Methods: A prospective, randomized, cross-over clinical trial was conducted in 40 patients aged from 18 to 45 years who underwent surgical extraction of impacted lower third molars at the Department of Oral Surgery in the Odontological Hospital of the University of Barcelona during the year 2011. Patients were randomly divided in 2 groups. Two different techniques (hermetical closure and partial closure of the wound) were performed separated by a one month washout period in each patient. Postoperative pain, swelling and trismus were evaluated prior to the surgical procedure and also at 2 and 7 days postoperatively. Results: No statistically significant differences were observed for pain ( p <0.06), trismus ( p <0.71) and swelling ( p <0.05) between the test and the control group. However, the values of the three parameters related to the test group were lower than those for the control group. Conclusions: Partial closure of the flap without suturing the relieving incision after surgical extraction of lower third molars reduces operating time and it does not produce any postoperative complications compared with complete closure of the wound.