Study design: randomized controlled trial. Setting: Institute of Psychiatry from FMUSP (Ipq-FMUSP). Subjects: patients seeking for Social Phobia treatment at IPq-FMUSP ( before and under treatment). Controls: Hospital staff at the HC-FMUSP or volunteers from a list of other studies conducted at the Ipq-FMUSP. Methods: Dental evaluation: probing depth, clinical attachment level and bleeding on probing will be recorded at 6 sites per tooth, as well as the plaque and/or calculus indexes. The number of decayed, missing and filled teeth (DMFT index) will be also assessed. The visual analogue scale (VAS) will be applied for the assessment of pain after probing after the probing recording. Patients will receive a clinical evaluation for halitosis using a Halimeter® to verify the concentration of the volatile sulfur compounds (before and after periodontal treatment). Main psychiatric assessment: Structured Clinical Interview (SCID) for DSM-IV-TR adapted for DSM-5, the Liebowitz Social Anxiety (LSAs). Duration and frequency: after the initial clinical assessment (dental and psychiatric) patients will be randomized into three groups. Two groups (experimental- social phobia with no psychiatric treatment and control) will receive periodontal treatment after the initial psychiatric evaluation. One group will receive periodontal treatment after the improvement of psychiatric condition (3 months after the initial assessment). The non-surgical periodontal treatment will be performed preferably within 24 h. Patients will be reevaluated 3 and 6 months after the end of nonsurgical periodontal treatment.