The application of metallic plates and screws for internal bone fixation is accepted with disadvantages, such as the bone atrophy from stress, and the ionization of metal. Because of these disadvantages, we usually remove the devices six months after the first operation. To substitute the metallic materials, we have developed new resorbable osteosynthesis systems for maxillofacial surgery. Polyglycolide (PGA), polylactide (PLA) and polydioxanone (PDS) are biodegradable substances used for surgical materials and PLA is considered the most suitable for bone fixation because it is the strongest. PLA are made from lactic acid polymers. Poly-L-lactide (PLLA) materials, such as SR-PLLA, As-polymerized PLLA and High-strength PLLA, are used clinically. Our High-strength PLLA material has lower molecular weight and crystallinity but it is stronger than the other PLLA materials. We treated 51 patients with mandible fractures and other oral diseases, using High-strength PLLA plates or screws. Follow-up studies were done by clinical, radiographic and laboratory examinations. After passing more than 2 years following operation, in 13 of the 20 cases the plates were palpable through soft tissue. However, the healing of the bone wound was uneventful in every case through our follow up period. These results lead us to conclude that our PLLA osteosynthesis system can be considered safe and useful for internal fixation in maxillofacial surgery.
In cases of multiple primary cancers, the combination of head/neck cancer and upper digestive tract cancer is often found. However, it is extremely rare for maxillary sinus cancer and esophageal cancer to occur simultaneously. This paper reports on an autopsy case of double primary cancers of the maxillary sinus and esophagus. The patient had been suffering from carcinoma of the maxillary sinus for about 12 months but the lesion was uncontrollable. At autopsy, the following two primary carcinomas were found : one was a moderately differentiated squamous cell carcinoma originated from the maxillary sinus infiltrating into the hard palate and tongue, with metastases in several regional lymph nodes, a para-aortic lymph node and bilateral lungs. The other was a progressive, well-differentiated squamous cell carcinoma originated from the esophagus transformed mucosa with epithelial dysplasia. Furthermore, two masses of gastrointestinal mesenchymal tumors (GIMT) of the stomach were noted.