Supportive periodontal therapy (SPT) succeeds the active phase of periodontal therapy. SPT includes repeated supra- and subgingival scaling and root planing (SRP) at all sites with bleeding on probing and pocket depths ≥ 4-5 mm. Despite the fact that this treatment approach has been proven to be extremely successful, on a long-time basis, it is associated with substantial hard tissue loss (i.e. root cementum and dentin) that may lead to an increase in hypersensitivity, weakening of the tooth and even endodontic complications. Therefore, a novel treatment concept (Guided Biofilm Management or GBM) consisting of removal of all soft supra- and subgingival bacterial deposits by means of an erythritol powder air-polishing, followed by the local, precise removal of supra and subgingival hard deposits (e.g. calculus) and subsequent use of another sub- and supragingival erythritol powder air-polishing, has been introduced. Here, the investigators will compare this novel concept (GBM) with the conventional care during SPT using hand curettes.

There is solid scientific evidence demonstrating that the clinical results obtained following active periodontal therapy can be maintained on a long-term basis provided that regular supportive periodontal therapy (SPT) is rendered. On a routine basis, SPT includes repeated supra- and subgingival scaling and root planing (SRP) at all sites with bleeding on probing and pocket depths ≥ 4-5 mm. Despite the fact that this treatment approach has been proven to be extremely successful, on a long-time basis, it is associated with substantial hard tissue loss (i.e. root cementum and dentin) that may lead to an increase in hypersensitivity, weakening of the tooth and even endodontic complications. Since patients enrolled in SPT have usually probing pocket depths (PPD) < 6 mm and limited supra- and subgingival deposits, the question arises whether SRP by means of hand and ultrasonic instruments may be needed at all sites with a PPD > 4 mm with BOP (+) that do not exhibit hard bacterial deposits (e.g. supra and subgingival calculus). It has been repeatedly shown that bacterial deposits can be removed from the root surfaces by mere polishing without any SRP, thus leading to comparable clinical outcomes than following the use of conventional SRP by means of hand instruments (e.g. metal curettes). The removal of "diseased" root cementum is therefore not necessary to accomplish clinical success. Results from a recent "in-vitro" study using a novel "subgingival pocket model" have shown that compared to hand instrumentation, the application of an air-polishing with erythritol prevents substance-loss and results in a smooth surface with nearly no residual biofilm that promotes the reattachment of PDL fibroblasts. These findings are in line with the results of a randomized controlled clinical study which has shown that biofilm removal by means of an erythritol powder based air-polishing yielded similar outcomes to those obtained with conventional SRP. Moreover, the use of the erythritol powder air-polishing yielded statistically and clinically better patient acceptance.

Based on these results a novel treatment concept (Guided Biofilm Management or GBM) consisting of removal of all soft supra- and subgingival bacterial deposits by means of an erythritol powder air-polishing, followed by the local, precise removal of supra- and subgingival hard deposits (e.g. calculus) and subsequent use of another sub and supragingival erythritol powder air-polishing, has been introduced.

The authors hypothesize that this approach may enable to render a more personalized and precise treatment for patients enrolled in SPT, thus leading to less hard tissue loss and better patient acceptance.

Inclusion Criteria:

• Written informed consent
• Patient adherent to supportive periodontal therapy
• With < 6 mm probing pocket depth (PPD)

Exclusion Criteria:

• Clinically significant concomitant diseases
• Enrolment in a clinical trial