Non surgical therapy or causal therapy allows, through the elimination of plaque (primary etiological factor) and calculus from the corono/radicular surfaces, a lowering of the total bacterial load. This therapeutical action reduces the risk of onset, or of progression, of gingival diseases such as gingivitis or periodontitis. From a clinical point of view it is generally possible to record a significant improvement of the most commonly used periodontal indices (Plaque Index and Gingival Index), a reduction of periodontal probing depths, and a gain of clinical attachment levels.