A Study of Tensile Degradation of Bioresorbable Materials Used for ...

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Degradation of Bioresorbable Tensile Bars suffer higher stress in median and paramedian fractures then in column or angle fractures. A prediction was made that insisted contact between the mandible and the fixation plate is necessary for successful function of the surgery. Results of the experiment using bioresorbable plates showed that the biomaterials can be used in certain circumstances of mandibular fractures. Median and paramedian fractures are best treated using two fixation plates, while angle fractures should be treated with one if contact with the lower portion of the bone is certain. One plate must also be used in a column fracture, and the plates must be approximately 2.0 or 2.5 mm in thickness. Bioresorbable fixation plates can be used in mandibular fractures in circumstances where a perfect alignment of repositioning is a guaranteed result. However, these plates are not successful when used in a mandibular column fracture (Krach et al., 2008, p. 67). PLA/PGA Plates and Screws for Internal Fixation of Mandibular Fractures Progress in the areas of biomaterials testing has produced a surge in using the biomaterials as fixation devices in fractures of the mandible. This study by Ferretti tested PLA/PGA compounds as plates and screws in the fixation of mandibular fractures in 31 patients. Follow up visits for patients occurred at 1 week, 6 weeks, and 3, 6, and 12 months post surgery. Pain and swelling were some of the symptoms for which patients were checked. Twenty-nine patients completed the trial with complete union of the bone fracture. Two participants in the trial were withdrawn when they were unwilling to return for a follow up or had been assaulted (Ferretti, 2008, p. 242). General anesthesia and amoxicillin were used during the surgery. The PLA/PGA compound used in this trial was 82% lactide and 18% glycolide. After the operation, patients stayed on oral amoxicillin for 5 days, and a particular mouthwash was used to keep the site of surgery disinfected. Furthermore, all patients were kept on a liquid diet for 6 weeks (Ferretti, 2008, p. 243). The results of this study show that PLA/PGA fixation has a 22.5% complication rate. Twenty patients completed the trial with no complications subsequent to the surgery. Complications were present in 9 patients, but no patients suffered a non-union of the fracture. Because the complication rate of using titanium fixation ranges from 13.7% to 43%, PLA/PGA polymer plate and screw fixation of mandibular fractures is an excellent alternative (Ferretti, 2008, p. 242). Biodegradable Fixation of Mandibular Fractures in Children Recently researchers have expressed an interest in bioresorbable fixation in children. One study at the Medical University of Vienna aimed to discover the safety and stability of short term results of biodegradable fixation in fractures of children’s mandibles. Thirteen children, ages ranging from 5 to 16 years, participated in this trial. They were all operated on for various fractures of the mandible and attended follow-up visits for approximately 2 years after the surgery was performed (Yerit, Hainich, Enislidis, Turhani, & Klug, 2005, p. 1). All patients experienced full union of the mandibular fracture. None of the participants suffered from undesirable reactions to the biodegradable materials. All complications experienced were minor and none forced removal of the biodegradable plates. The results depict that pediatric patients take well to biodegradable fixation of mandibular fractures. Children can benefit from biomaterials because mobility is achieved faster than if titanium is used. Also, the patients will not need to undergo a second removal surgery that is especially uninvited in pediatric patients. These results depict that biodegradable fixation is safe and superior to titanium in pediatric patients. Further studies will be necessary to establish the long term effects and reliability of biomaterials used in children (Yerit et al., 2005, p. 1). 9
Degradation of Bioresorbable Tensile Bars Products There are several companies that produce bioresorbable materials in various forms and sizes. Micro Engineering Solutions is a company that designs minuscule medical appliances and devises prototypes of these machines. Scores of devices made by Micro Engineering Solutions are biomaterials. Tornier, a medical manufacturing company, makes a product known as the Resorbable Fixation System that can be used as a tensile system in fractured bones. Some other leading manufacturers of bioresorbable materials are Purac, Lakeshore, and BI. Research Plan Titanium in hip replacements is the most common biomedical application used today. However, when titanium is put into the body, it lasts forever or must be extracted through a second surgery. Resorbable fixation systems are a new material that can be used in healing minor bone fractures. These resorbable materials have the ability to be morphed in the form of screws, plates, or mesh. Moreover, the materials will dissolve into the body as water and carbon dioxide subsequent to the fracture being healed. These bioresorbable materials are formed from polymers of poly-lactic acid compounded with poly-glycolic acid. These PLA/PGA compounds are the most common types of bioresorbables. This research will uncover how the length of time a resorbable material is in water affects the bioerosion of the material in comparison to the strength of titanium. This will help demonstrate whether titanium or resorbable fixation is a better choice for biomedical healing. Goals It is hypothesized that after six weeks, the strength of the resorbable materials will have decreased significantly. The final strength of the resorbable materials will be different from the strength of the titanium. The bioerosion rate of bioresorbable materials will be tested in water. Bioerosion is caused by water entering the polymer and hollowing out the inside, which causes the polymer to crumble. The independent variable will be the length of time the bioresorbable sample will remain in the water. The dependent variables will be the dimensions of the bioresorbable and the strength of the bioresorbable. The solution will be controlled and one variable will be kept in a nitrogen sealed pouch to maintain its original strength and dimensions. The dimensions of a bioresorbable bar will be measured without placing it in any solution. The strength of the bioresorbable will then be tested using an Instron tensile testing machine. Following the previous test, approximately thirty bioresorbable bars will be placed into the water. The dimensions will be measured and the strength of five samples each week for six weeks will be tested. To find the strength and dimensions, an Instron tensile tester will be used. This will supply the average amount of degradation of resorbable materials over the course of a realistic time frame for bone regeneration. Similarly, the titanium samples will be put in water and tested for both strength and dimensions each week. Once the data is collected, statistical analysis will be applied to find if there is a statistically significant difference in the original strength and dimensions and the final strength and dimensions. Using this information, a conclusion will be made about whether bioresorbable polymers are really a more effective healing process than titanium bone screws. 10
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