Page 16 - MSAM-4-2

Materials Science in Additive Manufacturing Hydrogels in mandibular reconstruction

primarily focus on passive defense measures, including inhibiting Escherichia coli, Staphylococcus aureus, and oral
antimicrobial dressings, localized growth factor release, bacteria through sustained gentamicin release.
54
53
and hyperbaric oxygen therapy. However, limitations Beyond metal ions, antibacterial agents, and peptides,
55
imposed by the unique oral environment – continuous photothermal therapy is widely explored in antibacterial
saliva washing, mechanical stress from mastication, hydrogel research. When localized temperatures exceed
and temperature/humidity fluctuations – result in short 48°C, irreversible thermal ablation directly eliminates
residence times and low bioavailability for conventional pathogens, while hydrogel carriers optimize heat
therapies. To address these challenges, functionalized distribution to minimize collateral tissue damage. In the 41
hydrogel systems with environmental adaptability offer – 47°C range, hyperthermia synergizes with chemotherapy
unique advantages. Their 3D network structures enable or photodynamic therapy by accelerating oxidative
precise loading of diverse active components (antibacterial stress responses. Mild hyperthermia (<41°C) enhances
peptides, metal ions, and exosomes), enhancing drug antibacterial effects through physical microenvironment
delivery efficiency and stability, thereby providing more modulation. Miao et al. integrated black phosphorus
63
effective solutions for oral tissue repair and antimicrobial (BP) nanosheets into hydrogels to construct BP/Gel NC
therapy. hydrogels, which exhibited excellent near-infrared (NIR)
Researchers have developed hydrogels crosslinked photothermal performance both in vitro and in vivo.
with antibiotics or antibacterial peptides to effectively When exposed to NIR irradiation, the hydrogel exhibited
56
57
inhibit bacterial growth. However, prolonged use of potent antibacterial properties. Furthermore, the BP
antibiotics and antimicrobial agents risks drug resistance nanosheet-hydrogel matrix promoted osteogenesis in vitro
and disrupts oral microbial homeostasis. To overcome this, without exogenous osteoinductive factors and stimulated
Chen et al. innovatively incorporated polyamidoamine significant new bone formation in a rat cranial defect
58
dendrimers (PAMAM-G3) into polymer backbones model.
to capture negatively charged microbial-associated
molecular patterns, creating cationic hydrogels that 3.2.2. Biodegradability
alleviate bacterial-induced inflammation while preserving Hydrogels can provide essential support during bone
oral microbial balance. Furthermore, incorporating healing while gradually degrading in sync with bone
inorganic antibacterial components into hydrogels not remodeling, thereby avoiding potential inflammation
only strengthens their antimicrobial performance and caused by long-term retention. The mandible exhibits
durability but also mitigates the likelihood of triggering faster remodeling rates compared to other bones,
64
bacterial resistance, offering a sustainable strategy for particularly during alveolar bone formation, which
infection control. Leveraging synergistic crosslinking necessitates that hydrogel degradation rates synchronize
between SH-PEG and Ag , researchers embedded viscous with rapid mandibular ingrowth while eliminating the
+
liposomes into PEG hydrogels to construct an injectable, trauma associated with secondary surgical removal
antibacterial, and self-healing drug delivery system, of traditional materials. Excessively slow degradation
59
offering innovative solutions for bone tissue engineering may hinder timely replacement by nascent bone tissue
and anti-infection therapy. Antibiotic-loaded hydrogels are during repair, delaying mandibular healing. Conversely,
widely applied in mandibular reconstruction. Preclinical overly rapid degradation could compromise mechanical
studies focus on local delivery of antibiotics (gentamicin support and impair bone repair efficacy. Zheng et al.
39
and vancomycin) through hydrogels to enhance anti- innovatively incorporated inorganic mesoporous bioactive
infective capacity and promote bone regeneration. In a glass (MBG) nanoparticles as in situ sustained-release
60
rabbit mandibular osteomyelitis model, local injection crosslinkers, overcoming the challenges in controlling
of gentamicin-loaded collagen hydrogel significantly gelation rates inherent to traditional divalent ion-
increased bone area in infected regions after 4 weeks, alginate systems. This approach stimulated Ca -release
2+
demonstrating superior antibacterial and osteogenic in weakly acidic microenvironments, accelerating MBG
effects. This strategy not only improves drug stability degradation and generating enhanced porous structures
61
and delivery efficiency but also reduces systemic side in situ. Concurrently, the increasing porosity from MBG
effects, supporting optimization and clinical translation of degradation facilitates cellular infiltration into hydrogels,
mandibular substitutes. Xu et al. designed a novel peptide- ensuring rapid tissue regeneration. However, excessively
62
based polymer with excellent antibacterial properties, high degradation rates may cause wound collapse,
capable of killing bacteria, releasing growth factors, preventing effective filling of defect areas by new tissue.
and promoting bone regeneration. This polymer carries To address this, Parsaee et al. successfully developed
65
BMP-2 and gentamicin-loaded microspheres, effectively a stable chitosan/collagen composite hydrogel system

Volume 4 Issue 2 (2025) 10 doi: 10.36922/MSAM025070006