# Peri-Implantitis Causal Therapy with and Without Doxycycline: Retrospective Cohort Clinical Study
###### Abstract  
Background: Topical application within peri-implant pockets ensures high drug concentrations at the infection site while minimizing systemic exposure. However, the comparative effectiveness of non-surgical causal therapy alone versus its combination with doxycycline remains unclear. This retrospective observational clinical study aimed to evaluate the impact of adjunctive doxycycline on peri-implant parameters, considering smoking, systemic conditions, and implant-prosthetic rehabilitation (single implant, implant-supported bridge, or full-arch). Methods: Patients were retrospectively assigned to a control group (CG), receiving non-surgical causal therapy alone, or a test group (TG), which is also treated with topical doxycycline. Peri-implant parameters, including Peri-implant Probing Depth (PPD), Bleeding on Probing (BoP), Plaque Index (PI), and suppuration, were assessed at baseline (T0) and follow-up (T1). Multivariate logistic regression and stratified subgroup analyses were conducted to adjust for confounders such as smoking, systemic conditions, and implant-prosthetic rehabilitation types. Results: Two hundred nine patients were included in the study, of whom 97 were in the CG and 112 were in the TG. At T1, the TG exhibited a statistically significant reduction in PPD, BoP, PI, and suppuration compared to the CG (\(p<0.05\)). Conclusions: The adjunctive use of topical doxycycline significantly enhances clinical outcomes in non-surgical peri-implantitis treatment. Further longitudinal studies are needed to confirm these findings and assess long-term stability. p 2020 IEEE/RSJ International Conference on Intelligent Systems (IEEE), Vol., pp. 2020-2020, 202  
The occurrence of peri-implantitis is impacted by several factors. Known risk indicators include individual behaviors and conditions such as smoking and diabetes mellitus, which impair immune response and the healing process, resulting in patients being more susceptible to chronic bacterial infection [14]. In addition, inadequate oral hygiene is a key factor in peri-implantitis development, as it allows bacterial biofilm aggregation around the implant. Other risk determinants include genetic predisposition (e.g., the presence of specific alleles for pro-inflammatory cytokines such as IL-1\(\beta\)) and local factors such as implant geometry, prosthetic restoration design, and implant placement. Implants with rough surfaces or a subcrestal location increase the likelihood of deep bacterial colonization, making decontamination more difficult [15; 16]. The therapeutic management of peri-implantitis is multifaceted and includes non-surgical and surgical approaches, each with distinct goals. Non-surgical therapies aim to decontaminate implant surfaces using mechanical instruments, such as titanium scalers, sonic instruments, and ultrasound with compatible material inserts. However, effective removal of bacterial biofilm could be impaired by the roughness of the implant surface and threads, where biofilm may persist even after treatment [17]. Chemical approaches, such as chlorhexidine or hydrogen peroxide injection to irrigate the peri-implant pocket, are often combined with mechanical decontamination to increase the effectiveness of bacterial removal [18]. Although these strategies are available, mechanical decontamination alone may not be enough to halt peri-implantitis progression in severe cases, requiring additional adjuvant interventions. Antibiotic employment in the management of peri-implantitis has been investigated in several clinical investigations and systematic reviews. Antibiotics can be administered systemically or locally. Systemic antibiotics, such as amoxicillin and metronidazolezo, are often recommended for reducing bacterial load in the context of severe infections. However, systematic reviews by [PERSON] et al. [19] and [PERSON] et al. [20] suggest that systemic antibiotics are not the most effective solution in the peri-implantitis management context.