Context and challenges of maxillofacial prosthetic rehabilitation

The management of patients with congenital, traumatic, or oncological craniofacial defects constitutes a major challenge in maxillofacial prosthetics. To date, and despite advances in materials science, no artificial substitute has succeeded in fully replicating the complex appearance and dynamic behavior of human skin. Practitioners are faced with materials whose mechanical and aesthetic properties inevitably degrade over time upon contact with the clinical environment.

This narrative review provides a comprehensive synthesis of materials used in maxillofacial rehabilitation, structuring the analysis around three pillars: conventional materials, digital technologies, and nanotechnology. The authors' objective is to evaluate the clinical performance and limitations of current solutions — particularly silicone elastomers — while identifying the transformative potential of digital workflows (CAD/CAM, 3D printing) and digital shade-matching systems to improve the precision and reproducibility of prostheses.

The synthesis explores the hypothesis that incorporating nanoparticles (titanium dioxide, zinc oxide, silver) into elastomeric matrices overcomes the persistent obstacles of low tear strength and chromatic instability. The authors postulate that the convergence between materials science, artificial intelligence, and digital manufacturing is now essential to optimize long-term functional and aesthetic outcomes.

Review methodology

This publication is a narrative review aiming to provide a comprehensive synthesis of the evolution of maxillofacial prosthetic materials. Unlike an experimental study, this work compiles and analyses existing data on the clinical performance and limitations of rehabilitation technologies.

The scope of the review's analysis is structured around three technological categories:

• Conventional materials: Evaluation of acrylic resins, polyvinyl chloride (PVC) derivatives, polyurethane elastomers, and silicone elastomers (identified as the gold standard).
• Digital workflows: Analysis of the integration of computer-aided design and manufacturing (CAD/CAM), 3D printing, and digital color matching systems for the precision and reproducibility of prostheses.
• Nanotechnology: Study of the incorporation of specific nanoparticles, notably titanium dioxide, zinc oxide and silver, within elastomer matrices.

The authors evaluated these materials based on critical clinical criteria: biocompatibility, flexibility, tear resistance, color stability, and antimicrobial properties induced by nanomaterials.

Summary of performance of maxillofacial rehabilitation materials

This narrative review synthesizes data regarding conventional, digital, and nanotechnological materials. The authors report that, despite the absence of specific numerical values or detailed p-values in this global synthesis, clear trends emerge regarding the evolution of clinical protocols.

Comparison of conventional materials

The synthesis identifies silicone elastomers as the current "gold standard" in clinical practice. The following table summarizes the qualitative observations reported on conventional materials:

Contributions of digital workflows and additive manufacturing

The integration of digital technologies transforms the precision of rehabilitation. The authors highlight three major areas of improvement:

• Precision and reproducibility: The use of computer-aided design and manufacturing (CAD-CAM) and 3D printing reduces the human errors inherent in manual methods.
• Efficiency: Optimization of prosthesis manufacturing time.
• Colorimetry: Digital color matching systems improve aesthetic integration compared to traditional visual methods.

Impact of nanoparticle incorporation

The review highlights that the integration of nanomaterials into elastomeric matrices makes it possible to overcome the intrinsic weaknesses of conventional silicones. The reported observations include:

• Titanium dioxide (TiO2) and Zinc oxide (ZnO): Notable improvement in color stability and reinforcement of the mechanical structure.
• Silver (Ag): Provides antimicrobial properties to prosthetic matrices, potentially limiting tissue infection complications.

In conclusion of this analysis, the authors indicate that the emergence of hybrid materials and the integration of artificial intelligence constitute the next step to more faithfully simulate the appearance and behavior of human skin.

A technological transition to overcome the limitations of silicone

The authors of this narrative review highlight a frustrating clinical reality: despite its status as the "gold standard", silicone elastomer still fails to perfectly mimic human skin over the long term. Practitioners face chromatic instability and limited tear resistance. The interest of this synthesis lies in demonstrating that improving results will no longer depend solely on conventional polymer chemistry, but on the integration of nanotechnology.

The introduction of titanium dioxide (TiO2), zinc oxide (ZnO), and silver (Ag) nanoparticles into elastomer matrices transforms the intrinsic properties of prostheses. According to reported data, these additives not only reinforce the mechanical structure but also confer essential antimicrobial properties for the health of peri-prosthetic tissues. In parallel, the transition to digital workflow (CAD/CAM, 3D printing) eliminates the reproducibility biases inherent in traditional manual methods.

This review nevertheless has limitations, notably its narrative nature which does not allow for a comparative statistical analysis of the different materials mentioned. While hybrid technologies and artificial intelligence are presented as the future of the discipline, their immediate accessibility in dental practices remains to be confirmed.

Study summary

This narrative review confirms that silicone elastomers remain the clinical standard in maxillofacial rehabilitation due to their biocompatibility, despite perfectible chromatic stability and tear strength. The integration of nanoparticles (TiO2, ZnO, Ag) now allows for the reinforcement of these elastomeric matrices while providing antimicrobial properties, complemented by increased precision via CAD/CAM digital workflows and 3D printing.

In concrete terms, for the practitioner:

• Optimize precision: Adopt digital workflows (CAD/CAM, 3D scanning) to ensure exact reproducibility of the prosthesis and reduce manual implementation errors.
• Improve durability: Consider using nanoparticle-doped materials for cases requiring high mechanical resistance or increased antibacterial protection.
• Manage aesthetic expectations: Inform your patients that, despite technological advances, the chromatic aging of silicones requires regular monitoring to maintain the visual integration of the substitute.

Technical lexicon of the study

Silicone elastomers: Materials considered the gold standard in maxillofacial prosthetics for their biocompatibility and flexibility, although limited by their tear resistance and chromatic instability.

CAD/CAM: Computer-aided design and manufacturing, digital technologies that increase the precision, reproducibility, and efficiency of the manufacturing process for craniofacial prostheses.

3D printing: Additive manufacturing technique mentioned as a major advancement in digital workflows for the creation of customized artificial substitutes.

Nanotechnology: An approach consisting of incorporating nanoparticles (titanium dioxide, zinc oxide, silver) into elastomeric matrices to improve their mechanical properties, color stability, and antimicrobial capabilities.

Tear strength: Mechanical property describing the ability of a material to resist the propagation of a cut; identified here as an intrinsic limitation of conventional silicones.

Color stability: Ability of the prosthetic material to maintain its aesthetic properties and its mimicry with human skin over time, a persistent challenge for current materials.

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