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. 2025 May 14:6:1578484.
doi: 10.3389/froh.2025.1578484. eCollection 2025.

A retrospective study on the impact of different antibiotic regimens in non-surgical periodontal therapy on microbial loads and therapy outcomes

Nils Werner  1 , Vinay Pitchika  1 , Katrin Heck  1 , Christina Ern  1   2 , Richard Heym  1   2 , Ali Al-Ahmad  3 , Fabian Cieplik  3 , Falk Schwendicke  1 , Caspar Victor Bumm #  1   2 , Matthias Folwaczny #  1
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A retrospective study on the impact of different antibiotic regimens in non-surgical periodontal therapy on microbial loads and therapy outcomes

Nils Werner et al. Front Oral Health. .

Abstract

Introduction: This study aimed to analyse the impact of different antibiotic regimens during non-surgical periodontal therapy on the microbial load of selected periodontitis-associated bacteria (PAB) and the primary therapy outcomes.

Methods: For this aim, 259 patients received steps I and II of periodontal therapy and were included in this clinical trial. 202 patients were treated without the adjunctive use of systemic antibiotics, 18 received amoxicillin (AMOX) as well as metronidazole (MET) and 39 only MET. Subgingival biofilm samples were quantitatively analysed for selected PAB using DNA-DNA-hybridisation-based detection assays for microbial loads of PAB before and 6 months after treatment. Changes in the microbial load of PAB and achievement of a "treat-to-target" endpoint (T2T) (≤4 sites with probing depth ≥5 mm) were analysed. Patients' subgingival microbial load was significantly reduced following therapy.

Results: 38.2% of the patients achieved T2T. Binary logistic regression adjusted for confounders indicated a relationship between residual PAB levels and not achieving T2T. In patients not receiving systemic antibiotics a 2.4-fold increased risk of not reaching T2T after steps I and II therapy was observed (none vs. MET aOR = 2.38 p = 0.44). Linear regression analysis adjusted for T0 PAB concentration and confounders revealed an increased reduction of PAB levels in patients with systemic antibiotics. No difference in PAB reduction or chance of achieving T2T was observed between MET and MET + AMOX.

Discussion: Microbial loads of PAB were found directly associated with periodontal status. As antibiotic treatment with both MET and MET + AMOX similarly reduced microbial loads of PAB, treatment with MET alone may be sufficiently effective as adjunctive to non-surgical periodontal treatment. To confirm this, further prospective studies with bigger sample size are needed.

Keywords: antibiotic resistance; antibiotics; periodontal bacteria; periodontal therapy; periodontitis.

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Conflict of interest statement

The author(s) declared that they were an editorial board member of Frontiers, at the time of submission. This had no impact on the peer review process and the final decision.

Figures

Figure 1
Figure 1
Flow diagram of the process of trial inclusion/exclusion.
See this image and copyright information in PMC

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