Delayed Infection of Porous Polyethylene Implants After Oncologic Maxillectomy and Reconstruction: 2 Case Reports and Review of Literature.

Medpor porous polyethylene implants are commonly used for facial skeletal reconstruction due to reported biocompatibility, fibrovascularization, and durability. While uncommon, late implant infections are an important consideration. We report delayed infections in 2 patients after unilateral total oncologic maxillectomy and reconstruction using Medpor implants for an ossifying fibroma and squamous cell carcinoma, respectively. In the first patient, annual interval computed tomography (CT) scans showed no recurrence of tumor or inflammatory changes. The second was lost to follow-up after adjuvant chemoradiation 1 year after resection. Patients both presented with swelling, drainage, and erythema around the implant at a mean of 4.5 years following maxillectomy. Both failed several attempts at conservative treatment. Cultures of implants removed at a mean of 2.5 months after infection grew α-hemolytic Streptococcus in the first and multiple organisms in the second, showing that the potential for delayed infection should be considered years after reconstruction.

Genomic identification of microbial species adhering to maxillofacial prostheses and susceptibility to different hygiene protocols.

This study investigated the microbial colonization of maxillofacial prostheses and support tissues using the Checkerboard DNA-DNA hybridization method, and the efficacy of 0.12% chlorhexidine gluconate, 10% Ricinus communis solutions, or brushing, on colony forming unit (CFU) reduction in monospecies biofilms (Candida glabrata, Staphylococcus aureus, Streptococcus mutans, Escherichia coli, Enterococcus faecalis, and Pseudomonas aeruginosa) formed on two silicones (MDX 4-4210 and Bio-Skin). Biofilm was harvested from 43 maxillofacial prosthesis wearers for detection of 38 species of microorganisms. The CFU counts of the six above mentioned species were recorded after using the hygiene protocols. All 38 investigated species were identified in prostheses and tissues, with a higher prevalence in the prostheses. 0.12% chlorhexidine gluconate immersion showed the greatest antimicrobial effectiveness, followed by mechanical brushing protocols. MDX 4-4210 silicone produced lower CFU counts than Bio-Skin.

Gentamicin-loaded poly(lactic-co-glycolic acid) microparticles for the prevention of maxillofacial and orthopedic implant infections.

Trauma and orthopedic surgery can cause infections as any open surgical procedures. Such complications occur in only1 to 5% of the cases, but the treatment is rather complicated due to bacterial biofilm formation and limited drug access to the site of infection upon systemic administration. An interesting strategy to overcome this type of complications is to prevent bacterial proliferation and biofilm formation via the local and controlled release of antibiotic drugs from the implant itself. Obviously, the incorporation of the drug into the implant should not affect the latter's biological and mechanical properties. In this context, we optimized the preparation process for gentamicin-loaded poly(lactic-co-glycolic acid) (PLGA) microparticles, which can be incorporated in the macropores of calcium phosphate-based bone substitutes. Microparticles were prepared using a double emulsion solvent extraction/evaporation technique. The processing parameters were optimized in order to provide an average microparticle size of about 60µm, allowing for incorporation inside the macropores (100µm) of the hydroxyapatite scaffold. Gentamicin-loaded PLGA microparticles showed a sustained release for 25-30days and a rapid antibacterial activity due to a burst effect, the extent of which was controlled by the initial loading of the microparticles. SEM pictures revealed a highly porous microparticle structure, which can help to reduce the micro environmental pH drop and autocatalytic effects. The biological evaluation showed the cytocompatibility and non-hemolytic property of the microparticles, and the antibacterial activity against Staphylococcus aureus under the given conditions.

Evaluation of Candida albicans adherence on the surface of various maxillofacial silicone materials.

OBJECTIVES: Fungal infection resulting from Candida adherence on material surface is one of the most important medical risks for maxillofacial prosthesis wearers. Despite wide usage, there is a sparse data evaluating C. albicans adherence on various commercial maxillofacial silicone materials that have different surface contact angles. The objective of this study was to investigate the relationship between surface contact angle and fungal adherence on widely used maxillofacial silicone materials. MATERIALS AND METHODS: Three maxillofacial silicone materials titled VST-50, A-2006, and A-2186F were used for fabrication of disc-shaped specimens. Surface contact angle of specimens were measured by the goniometric method. Adhesion quantity of two different C. albicans strains was evaluated with a colorimetric method using XTT/Coenzyme Q0. The Kruskal-Wallis and Mann-Whitney U tests were used for statistical analysis of data. RESULTS: The lowest surface contact angle values with the highest Candida adhesion quantity were measured on the specimens fabricated with A-2006 silicone material. Statistically significant differences were found among three maxillofacial silicone materials in terms of both surface contact angle values and adhesion quantity (P<0.01). CONCLUSION: There is a close relationship between surface contact angle and quantity of Candida adherence. However, it should be noted that various factors arising from material properties may affect the complex nature of the Candida adhesion process.

Disinfection of maxillofacial silicone elastomer using a novel antimicrobial agent: recombinant human beta-defensin-3.

Maxillofacial silicone elastomer, when used as a prosthesis, is in contact with wound surfaces and mucosa, and tends to be contaminated with microorganisms from a patient's saliva and blood. The aim of the study was to evaluate the efficacy of human beta-defensin-3 (HBD3) on the reduction of two resistant bacteria species from the surface of maxillofacial silicone elastomer. HBD3 cDNA was amplified from total RNA, which had been extracted from human gingival epithelium by means of reverse-transcription polymerase chain reaction (RT-PCR). Following this, the cDNA fragments were recombined in a prokaryotic expression vector. The constructed expression vectors pET-32a/HBD3 were transformed into Escherichia coli to obtain recombinant protein. After protein purification and refolding, the product was verified in classic antimicrobial experiments against Staphylococcus aureus and Candida albicans. Specimens made of silicone elastomer A-2186, which had been contaminated with S. aureus or C. albicans, were immersed in rHBD3 or 5.25% sodium hypochlorite (a positive control) for 5 min, 10 min, 30 min, or 60 min. The active recombinant HBD3 obtained in the current study eliminated the S. aureus and C. albicans microorganism from the surface of the maxillofacial elastomer after a 30-min immersion. There was no statistically significant difference between the rHBD3 group and the sodium hypochlorite 5.25% group. In conclusion, rHBD3 exhibits antibacterial activity against oral pathogenic strains that adhere to maxillofacial elastomer, and may, thus, contribute to the prevention of infections caused by S. aureus and C. albicans.

The resistance of maxillofacial reconstruction plates to biofilm formation in vitro.

OBJECTIVES/HYPOTHESIS: Bacterial biofilms, bacteria surrounded by a protective glycocalyx, have been demonstrated on bioimplants placed within and outside of the head and neck region. The presence of the biofilm often makes decontamination of an infected implant impossible, requiring removal of the implant. Infections attributable to biofilm formation within the facial skeleton after reconstruction with implants may result in delayed union, fibrous union, malunion, nonunion, and malocclusion. These complications often require removal of the implant and secondary surgery. Although the incidence of infections necessitating implant removal is relatively low, the increased numbers of implants being placed make this a growing problem. Previous work in the authors laboratory has demonstrated a resistance to biofilm formation on different types of pressure-equalizing tubes. The hypothesis evaluated in the study is that such resistance to biofilm formation is due to the inability of bacteria to adhere to the tubes because of the material's smoothness or surface charge. STUDY DESIGN: A controlled observational study. METHODS: Scanning electron microscopy was used to evaluate the formation of biofilms in vitro for a common strain of Staphylococcus aureus on four implantable materials. The implantable materials included titanium and polylactide resorbable plates. RESULTS: Consistent with the authors' prior findings, they were able to produce bacterial biofilm reliably on a silicone pressure equalizing tube but were unable to demonstrate biofilm formation on the titanium or resorbable implants. CONCLUSION: The absence of biofilm formation on these implants can best be explained by the surface charge or polarity properties of these materials. These findings are consistent with the relatively low incidence of infections among patients receiving these implants in maxillofacial applications.

Candida albicans growth on thermal cycled materials for maxillofacial prostheses in vitro.

In the present study, the growth of a single isolate of Candida albicans on saliva-, serum-coated or protein free (uncoated), thermocycled (4-70 degrees C for 1 min, respectively; 0, 1000 and 10 000 times) 15 commercial maxillofacial materials was investigated, by monitoring pH changes in growth media. The inhibitory effect of the tissue conditioners on fungal growth was analysed using three parameters viz: (i) delay in the onset of the rapid decline in pH (ii) reduction in the rate of pH change and (iii) the pH minima reached. In the case of control materials (non-thermocycled and uncoated), significant antifungal effect was observed with two products. However, the antifungal effect of the materials was significantly reduced both by thermal cycling (Analysis of covariance [ANOVA]; P < 0.01) and a layer of protein coating (saliva, P < 0.05; serum, P < 0.01). When the interrelation between three parameters of fungal growth and the surface hydrophobicity of the materials were analysed, minimum pH of fungal growth on 10 000-thermocycled materials correlated well with the contact angles of the materials (Student t-test, P < 0.01), suggesting that thermocycling process reduced the unpolymerized components of the materials which showed the antifungal effects, resulted in that the cell growth depends on the surface hydrophobicity of the specimens. These results, taken together, suggest that the ageing of the materials and the biological fluids of the host enhanced the fungal growth on maxillofacial materials.

Biomaterials in the face: benefits and risks.

An extensive review of biomaterials in the face was conducted in an American Society of Maxillo-facial Surgeons-sponsored biomaterials symposium. The symposium was held in Boston, MA, immediately preceding the 1998 annual meeting of the ASPRS/PSEF. The scope of the symposium extended from current reconstructive techniques for the facial skeleton, including autogenous bone and biomaterials, to potential application of new techniques in molecular biology that may enable the body's own tissues to be engineered to provide bone and cartilage to reconstruct the facial skeleton. The authors review the presentations and relevant literature on biomaterials in the face. The following topics are reviewed: current reconstructive techniques using autogenous bone grafts, methyl methacrylate cranioplasty, demineralized bone, and hydroxyapatite; biomaterials used for rigid fixation, including metallic and bioabsorbable implants; biomaterials used for facial augmentation, including porous polyethylene, hard-tissue replacement, and ceramic biomaterials; biofilm, or a layered polysaccharide matrix secreted by bacteria on the surface of implants; and potential means of inducing bone formation by directing the body's own tissues through cytokine interaction, gene transfer, and tissue engineering.

Microflora associated with percutaneous craniofacial implants used for the retention of facial prostheses: a pilot study.

Craniofacial implants have been used successfully for the retention of facial prostheses. However, complications occur that can lead to the loss of implant integration. One such complication is infection possibly resulting from crevicular microflora activity. As part of an ongoing study, samples from crevicular sites surrounding 17 craniofacial implants were collected and submitted for microbiological assay. The results demonstrated the presence of opportunistic pathogens in many sites regardless of subjects' hygiene efforts. The significance of the findings is reviewed.