Hydrogel tissue expanders for stomatology. Part I. Methacrylate-based polymers

Abstract

In order to create a soft tissue surplus, implantable volume expanders are often utilized in dental surgery. Implanted tissue expanders should gradually increase their volume, exerting a constant pressure on the surrounding tissue for weeks. Current tissue expanders are based predominantly on externally inflatable balloons or on osmotically active tissue expanders that use soft hydrogels wrapped in perforated plastic coatings, which limit fluid entry and swelling. We have designed and examined tissue expanders based on the controlled rate expansive hydrogels synthesized from copolymers of selected methacrylates and N-vinylpyrrolidone, cross-linked with a combination of non-degradable (glycol dimethacrylates) and hydrolytically degradable (N,O-dimethacryloylhydroxylamine) cross-linkers. These copolymers have close-to-linear volume expansion rates (up to 6-9 times their original volume) and exert an increasing swelling pressure in vitro. The anesthetic benzocaine has been incorporated into the hydrogels, and kinetic release experiments have shown that most of the drug (90%) was released within 48 h. Our proposed hydrogel expanders are homogeneous and have suitable mechanical properties, thus simplifying the surgical manipulations required. Further studies will be needed to completely evaluate their biocompatibility and tissue response to the implants.

Assessment and prevention of cartilage degeneration surrounding a focal chondral defect in the porcine model

“…Interestingly, both hydrogels reduced sGAG loss suggesting that swelling pressures of 13 kPa may be sufficient to minimize degeneration, but that higher swelling pressures (e.g., 310 kPa) may provide an even greater reduction in degeneration. This magnitude is similar to those reported during hydrogel degradation where swelling pressures increased from 50 to 800 kPa [22]. These swelling pressures may serve to physically prevent the adjacent tissue from swelling and thus minimize cartilage swellinginduced sGAG loss and/or provide mechanical signals to maintain homeostasis.…”

Tissue Expansion Improves the Outcome and Predictability for Alveolar Bone Augmentation: Prospective, Multicenter, Randomized Controlled Trial

“…Tissue expanders based on gradually swelling hydrogels that are permeable to hydrophilic compounds also allow the incorporation and subsequent release of pharmacologic agent such as anesthetics or antibiotics [26]. This aspect is conveniently utilized to reduce the patient's pain and discomfort during the expansion period with medication use.…”

Hydrogel Tissue Expanders for Stomatology. Part II. Poly(styrene-maleic anhydride) Hydrogels

“…In our previous study [17] we presented the synthesis of TEs in form of a solid and uniform hydrogel blocks without any membrane cover based on poly(2-hydroxyethyl methacrylate- co -methacrylic acid) copolymers. These hydrogels exhibited a close-to-linear volume expansion rates up to 3 to 4.5 times of their original volume using a combination of non-degradable and hydrolytically degradable crosslinkers, allowing the volume expansion even in a later stage due to the degradation of the polymer network accompanied by the additional increase in swelling.…”