The primary outcome of the present study was to assess the percentage of pocket closure, and the secondary aim was to evaluate the clinical performance in terms of clinical attachment level (CAL) gain, probing pocket depth (PPD) reduction, and gingival recession (REC) after the use of cavitron ultrasonic surgical aspirator (CUSA) in deep infrabony defects. Fourteen deep infrabony defects in 11 patients who were previously treated with active periodontal therapy followed by one year of supportive periodontal therapy (at least three sessions) were additionally treated by the aid of CUSA. Eighty-six percent of the initial defects (12 out of 14) resulted in a PD < 5 mm, showing complete resolution six months after CUSA treatment, without any adverse event and with negligible pain (VAS from 0 to 3). CUSA showed potential as a method to promote pocket healing, reduce PPD, and increase clinical attachment (P < 0.001) in deep infrabony defects. This trial is registered with ClinicalTrials.gov NCT03567161.