The purpose of this study is to compare the effects of extraoral and intraoral
low-level laser therapies (
LLLT) on postoperative
trismus and oedema following the removal of mandibular third molars. Forty-eight patients who were to undergo surgical removal of their lower third molars were studied. Patients were randomly allocated to one of three groups: extraoral
LLLT, intraoral
LLLT, or placebo. In the study, a Ga-Al-As
diode laser device with a continuous wavelength of 808 nm was used, and the
laser therapy was applied by using a 1 x 3-cm handpiece. The flat-top
laser beam profile was used in this
therapy. For both of the
LLLT groups,
laser energy was applied at 100 mW (0.1 W) for a total of 120 s (0.1 W x 120 s = 12 J). Patients in the extraoral-
LLLT group (n = 16) received 12-J (4 J/cm(2)) low-level
laser irradiation, and the
laser was applied at the insertion point of the masseter muscle immediately after the operation. Patients in the intraoral-
LLLT group (n = 16) received 12-J (4 J/cm(2)) low-level
laser irradiation intraorally at the operation site 1 cm from the target tissue. In the placebo group (n = 16), the handpiece was inserted intraorally at the operation site and then was touched extraorally to the masseter muscle for 1 min at each site (120 s total), but the
laser was not activated. The size of the interincisal opening and facial swelling were evaluated on the second and seventh postoperative days. At the second postoperative day,
trismus (29.0 +/- 7.6 mm [p = 0.010]) and swelling (105.3 +/- 5.0 mm [p = 0.047]) in the extraoral-
LLLT group were significantly less than in the placebo group (
trismus: 21.1 +/- 7.6 mm, swelling: 109.1 +/- 4.4 mm).
Trismus (39.6 +/- 9.0 mm [p = 0.002]) in the extraoral-
LLLT group at the seventh postoperative day was also significantly less than in the placebo group (29.0 +/- 6.2 mm). However, at the seventh postoperative day in the intraoral-
LLLT group, only
trismus (35.6 +/- 8.5 [p = 0.002]) was significantly less than in the placebo group (29.0 +/- 6.2 mm). This study demonstrates that extraoral
LLLT is more effective than intraoral
LLLT for the reduction of postoperative
trismus and swelling after extraction of the lower third molar.