Peri-implant infections: the challenge of 3D biofabrication

The restoration of tissue loss using 3D-printed implants allows for precise anatomical adaptation, but its clinical success is hindered by a major obstacle: implant-associated infections and biofilm formation. Systemic antibiotic therapies reach their limits here, often compromised by insufficient local diffusion and the emergence of bacterial resistance. In view of this, the development of devices with localized antimicrobial properties has become a clinical imperative.

This systematic review synthesizes recent advances in bio-printed antimicrobial scaffolds. The objective is to evaluate the effectiveness of three strategic approaches: the integration of inherently antibacterial materials, the use of stimuli-responsive platforms for on-demand action, and the engineering of mechanobactericidal micro-topographies. The central challenge analyzed by the authors is to validate the hypothesis that targeted bactericidal action can be maintained without altering the osteogenic activity or the osseointegration of the device, while overcoming industrial manufacturing complexities.

Methodology of the synthesis

This systematic review lists recent advances in the design of 3D-printed medical substitutes intended to overcome the limitations of systemic antibiotic therapies and biofilm formation. To structure the analysis of current innovations, the authors have classified the technologies according to three strategic and synergistic axes:

• Intrinsic action materials: Non-metallic systems (chitosan, antimicrobial peptides, graphene oxide) and metal-based systems (silver, copper, zinc, magnesium, MOF) acting through the release of ions or reactive oxygen species.
• Stimuli-responsive platforms: Use of exogenous physical fields (photothermal, sonodynamic, electrical stimulation) or endogenous biochemical signals (pH) to trigger a spatiotemporal bactericidal effect on demand.
• Topographic micro-structuring: Emulation of bio-inspired architectures inducing a mechanobactericidal action without added medication.

The methodological evaluation focuses on a critical balance for the practitioner: antimicrobial potency versus the maintenance of osteogenic activity and osseointegration. The synthesis thus analyzes sustained-release mechanisms and manufacturing complexities to define the success criteria for future anti-infective structures.

A synergy of three breakthrough strategies

This systematic review synthesizes recent advances in 3D-printed antimicrobial scaffolds, classifying innovations according to three major strategic axes. The common objective identified by the authors is to overcome the inefficiency of systemic antibiotic therapies against peri-implant biofilms.

The rise of smart and responsive platforms

Compiled data show that stimuli-responsive systems offer superior spatio-temporal regulation. For example, the use of ZIF-8@Copper Oxide nanocomposites (Ref. 11) integrated into 3D scaffolds allows for efficient repair of infected bone defects through an intelligent response to the micro-environment.

Even more innovatively, the review reports the emergence of autonomous devices:

• Activation by occlusion: Autonomous piezoelectric implants (Ref. 16) use masticatory forces to generate an adaptive preventive response against peri-implantitis.
• Ultrasonic catalysis: Ultrasound-activated piezo-hot carriers trigger a catalytic cascade leading to "cuproptosis" type bacterial death (Ref. 14), specifically targeting deep tissue infections.
• Chitosan efficacy: Studies on quaternized chitosan (Ref. 24) confirm an excellent balance between anti-infective efficacy and cellular biocompatibility, essential for osseointegration.

Translational challenges and biocompatibility

The synthesis highlights a critical point for the clinician: the balance between antimicrobial aggressiveness and the preservation of osteogenic activity. While metals such as silver or copper are highly bactericidal, their dosage must be finely regulated to avoid inhibiting osteoblasts. The authors note that micro-perforated structures and bio-inspired architectures allow for a mechanobactericidal effect without chemical toxicity, paving the way for "drug-free" implants (without antibiotics).

Analysis of antimicrobial strategies in 3D printing

This systematic review highlights a major paradigm shift: the progressive move away from systemic antibiotic therapy in favor of localized and multifunctional 3D devices. The clinical interest is immediate, as these scaffolds allow for bypassing antibiotic resistance by directly targeting the biofilm. The most striking innovation lies in stimuli-responsive platforms (photothermal, ultrasound, pH) that enable "on-demand" treatment, particularly effective for infections located in deep tissue compartments.

However, the authors identify a persistent translational challenge: maintaining the balance between bactericidal efficacy and cell survival. While metal ions (silver, copper, zinc) provide continuous defense, their dosage must be finely regulated to avoid inhibiting osteogenic activity or compromising the device's osseointegration. The manufacturing complexity of these bio-inspired micro-architectures constitutes the second barrier to routine clinical use.

Compared to traditional passive coatings, the use of inherently antibacterial materials such as chitosan or antimicrobial peptides (LL-37) offers superior biocompatibility. For the implantologist, this evolution suggests that long-term success will no longer depend solely on primary stability, but on the implant's ability to actively modulate its biochemical environment when faced with bacterial aggression.

Synthesis of technological advances

This systematic review reports the emergence of three strategies for 3D implants: the integration of intrinsic materials (chitosan, peptides, Ag, Cu, Zn ions), the development of stimuli-responsive platforms (NIR light, ultrasound, pH), and the use of bio-inspired micro-topographies. These innovations aim to eradicate biofilms without compromising osteogenic activity or inducing antibiotic resistance.

In concrete terms, for the practitioner:

• Local targeting: Anticipate the arrival of custom-made devices capable of locally releasing antimicrobial agents (Ag, peptides), reducing dependence on systemic antibacterials during complex bone reconstructions.
• Mechanical inhibition: Consider the future interest of implants with mechanobactericidal topographies that limit bacterial adhesion from the moment of placement, without medicinal input.
• On-demand treatment: Monitor the development of implants activatable by external physical fields (photothermia, piezoelectricity) to treat peri-implant infections in deep sites non-invasively.

Technical lexicon of the study

3D antimicrobial scaffolds: Customised porous three-dimensional structures, designed by additive manufacturing to fill tissue defects while ensuring targeted local antibacterial protection.

Antimicrobial peptides (AMPs): Non-metallic defense molecules (e.g., defensins, LL-37) integrated into implants to lyse bacterial membranes, offering an alternative to conventional antibiotics in the face of antimicrobial resistance.

Stimuli-responsive platforms: Delivery systems capable of modulating their bactericidal action in response to exogenous physical stimuli (electric fields, light) or endogenous biochemical cues (pH acidification related to infection).

Mechanobactericidal action: Strategy for the physical destruction of pathogens through contact with bio-inspired topographical micro-patterns, enabling bactericidal action without the use of pharmacological agents.

Metal-Organic Frameworks (MOF): Hybrid metal-organic networks used for the controlled release of bioactive ions or the generation of reactive oxygen species (ROS) within the implant site.

Sonodynamic stimulation: Use of ultrasonic waves as an exogenous physical field to activate bactericidal agents and treat infections located in deep tissue compartments.

Photothermy: Conversion of light radiation into local heat to eradicate bacterial biofilms in a spatiotemporal and on-demand manner.

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