Third molars extraction is a surgery frequently performed in dentistry. It is generally associated to a great postoperative distress rendered by pain, swelling and trismus, caused by surgical trauma inflammation. Several methods have been proposed to prevent these complications and to increase tissue repair quality. The use of low level laser therapy (LLLT) has been reported in dentistry since 1970. A large number of studies have reported the benefits of LLLT without collateral damage, positive effect as an anti-inflammatory agent and benefits in accelerating wound repair. However, some clinical applications strategies have been contradictories in everyday practice with results not always equivalent.

Objective: To verify if a single LLLT intra or extra oral application, singly, are analogous in their effects in controlling postoperative edema, trismus, pain and wound repair in third molar surgery.

30 healthy participants of both genders, with 18 to 35 years-of-age, with the necessity of inferior bilateral third molar removal will be selected. Inclusion criteria will consider the presence of upper central incisive and same surgical difficulty for third molar extraction. Participants that present chronic TMJ pain, neurological or psychiatric disorders, pericoronitis, anti-inflammatory or analgesic use for the last 15 days, bisphosphonates usage history at any time, tabagism, pregnancy or a family history of photosensitivity and hypersensibility to analgesics, anti-inflammatory or antibiotics will not be included. The surgical procedures will be randomized for the group to be assigned respecting the interval of one month between the surgeries.

Intra-oral group (IO) will be that in whose participant will receive the LLLT (Photon Lase III DMC equipment) with 660 nm wavelength, 100 mW of power, 107J / cm2 of power density, during 30 seconds, positioning the tip of the laser device in straight contact with each of the four points in the surgical area:

1. corresponding to the occlusal surface of the tooth surgically extracted,
2. in the middle third of the lingual surface, point
3. the middle third of the buccal surface and point
4. retro molar triangle region. Each point will receive energy 3J (Et= 12J).

The extra-oral group (EO) will receive phototherapy with the 808nm of wavelength following the same above protocol although positioning the laser point over the skin in straight contact with four points on the masseter muscle:

1. next jaw insert,
2. lower middle region,
3. upper middle region
4. near the insertion of the zygomatic arch.

In the IO group the extra-oral region will not be irradiated (the laser tip will be put in place without energy) in the EO group it will be done the opposite, so as the same patient will be the control because the participant will not be capable to identify which group he belongs to. The same investigator will perform surgical procedures and laser therapy. All participants will receive the same postoperative medication. Three distances will evaluate the range of edema: from tragus to the corner of the mouth, from gonial angle to the corner of the mouth and from gonial angle to the corner of the eye using a malleable millimeter rule. Trismus will be evaluated by the maximum range of mouth opening considering the inter-incisal distance between the edges of upper and lower right central incisors by a caliper in three moments: before surgery, 24 hours and 8 days after surgery. Participants will be asked to fill in a diary to assess the severity of postoperative pain on a visual analogue pain scale after the end of anesthetic effect: 4, 6, 8, 24, 48 hours postoperatively. The amount and time of medication will be also recorded. The quality of wound repair will be evaluated by two blinded calibrated observers, 24 hours and 8 days postoperatively in score from 0 to 3. The data will be submitted to appropriate statistical analysis for non-parametric samples.

Inclusion Criteria:

• necessity of bilateral impacted third molar removal with similar dental arch positioning and similar surgical difficulty.

Exclusion Criteria:

• Compromised Systemic Health status, Neurologic and/or mental disorders, local infection history, anti-inflammatory or analgesic use for the last 15 days, tabagism, ethylism, pregnancy.