Characterization of porous polymethylmethacrylate space maintainers for craniofacial reconstruction

Abstract

Porous polymethylmethacrylate (PMMA) has been used as an alloplastic bone substitute in the craniofacial complex, showing integration with the surrounding soft and hard tissue. This study investigated the physicochemical properties of curing and cured mixtures of a PMMA-based bone cement and a carboxymethylcellulose (CMC) gel porogen. Four formulations yielding porous PMMA of varied porosity were examined; specifically, two groups containing 30% (w/w) CMC gel in the mixture using a 7% (w/v) or 9% (w/v) stock CMC gel (30-7 and 30-9, respectively) and two groups containing 40% (w/w) CMC gel (40-7 and 40-9). An additional group comprising solid PMMA without CMC was investigated. The incorporation of the CMC gel into the PMMA bone cement during polymerization decreased the setting time from 608 ± 12 s for the solid PMMA to 427 ± 10 s for the 40-9 group, and decreased the maximum temperature from 81 ± 4°C for the solid PMMA to 38 ± 2°C for the 40-9 group. The porous PMMA groups exhibited reduced compressive strength and bending modulus and strength relative to the solid PMMA. All the porous PMMA formulations released more unconverted methylmethacrylate (MMA) monomer and N,N-dimethyl-p-toluidine (DMT) from cured specimens and less MMA and DMT from curing specimens than the solid PMMA. The data suggest that the physicochemical properties of the porous PMMA formulations are appropriate for their application in craniofacial space maintenance.

Biomaterials-aided mandibular reconstruction using in vivo bioreactors

“…Porous space maintainers were fabricated from PMMA and carboxymethylcellulose gel as previously described (12,36,37) using reagents prepared by Synthasome, Inc. Briefly, 7% (wt/vol) carboxymethyl cellulose was added to a bone cement powder phase consisting of polymerized methylmethacrylate/methacrylate copolymer, benzyl peroxide, and zirconium dioxide at a ratio of 30:70 carboxymethylcellulose/bone cement powder phase (wt/wt).…”

A rapid, flexible method for incorporating controlled antibiotic release into porous polymethylmethacrylate space maintainers for craniofacial reconstruction

“…Prewetting was investigated as a possible means to increase the infiltration of thermogelling liquid into the pores of the space maintainer by increasing the hydrophilicity of the bulk material, while simultaneously removing leachable methacrylate from the construct, improving the biocompatibility of the space maintainer. 18 While a moderate theoretical loading increase was projected in prewet samples, the prewetting appears to negatively impact loading of antibiotic. This indicates that potential affinity disparities between the thermogel, water, antibiotic, and bulk materials could have resulted in infiltration of more water without thermogel-bound antibiotic or increased diffusion of antibiotic from the construct during gelation.…”

“…10,19 When compared to solid polymeric space maintainers, porous implants have shown superior outcomes in terms of healing of the overlying soft tissue cuff. 9,10,18 However, the use of porous implants presents a challenge because the pores can harbor bacteria, resulting in a higher available surface area for biofilm formation and subsequent wound infection. 15,20,21 …”

Hepatic transcriptomic alterations for N,N-dimethyl-p-toluidine (DMPT) and p-toluidine after 5-day exposure in rats

“…S. Environmental Protection Program 2011). DMPT exposure is of concern because the chemical can leach from medical devices and dental materials (Wang et al 2013). The State of California has listed DMPT as a chemical known to cause cancer (Office of Environmental Health Hazard Assessment 2014) based on the results of a 2-year cancer study where liver tumors occurred in both rats and mice and nasal tumors in rats (National Toxicology Program 2012).…”