Non-surgical periodontal therapy is the gold standard in periodontitis treatment. What makes it a fundamental step in achieving and maintaining periodontal health is the consistency of positive clinical outcomes and the predictability of the results achieved. The standard procedure in non-surgical therapy includes supragingival plaque control in combination with subgingival scaling and root planing. Depending on the number of affected teeth and the amount of supra- and subgingival deposits, the therapy is fragmented into several visits, usually with one quadrant in focus. Despite the already established effective treatment modalities, non-surgical therapy faces its problems, in which there is an opportunity for progress and further research. One of the proposed methods for doing so is full-mouth therapy „FMT “- a relatively new paradigm. It is believed that when carrying out the quadrant-by-quadrant therapy, there is a possibility of translocation of pathogenic bacteria from untreated pockets to those in which scaling and root planing were completed during the previous visit. Therefore, the premise is to complete debridement of all affected pockets within a 24-hour time frame thus minimizing the possibility of translocation of the bacteria from non-treated pockets and other oral niches to already treated sites. Current clinical studies comparing these two modalities show results that either speak in favour of single-visit therapy or record statistically insignificant differences between the two. The definite advantage of one-visit therapy is less time consumption for the therapist and the patient.