ABSTRACT
Aim: To study the long-term survival of dental implants placed in native or grafted bone in irradiated bone in subjects who had received radiation for head and neck cancer. Materials and Methods: A retrospective chart review was conducted for all patients who received dental implants following radiation treatment for head and neck cancer between May 1, 1987 and July 1, 2008. Only patients irradiated with a radiation dose of 50 Gy or greater and those who received dental implants in the irradiated field after head and neck radiation were included in the study. The associations between implant survival and patient/implant characteristics were estimated by fitting univariate marginal Cox proportional hazards models. Results: A total of 48 patients who had prior head and neck radiation had 271 dental implants placed during May 1987-July 2008. There was no statistically significant difference between implant failure in native and grafted bone (P=0.76). Survival of implants in grafted bone was 82.3% and 98.1% in maxilla and mandible, respectively, after 3 years. Survival of implants in native bone in maxilla and mandible was 79.8% and 100%, respectively, after 3 years. For implants placed in the native bone, there was a higher likelihood of failure in the maxilla compared to the mandible and there was also a tendency for implants placed in the posterior region to fail compared to those placed in the anterior region. Conclusion: There was no significant difference in survival when implants were placed in native or grafted bone in irradiated head and neck cancer patients. For implants placed in native bone, survival was significantly influenced by the location of the implant (maxilla or mandible, anterior or posterior).
Subject(s)
Adult , Aged , Aged, 80 and over , Bone Transplantation/methods , Carcinoma, Squamous Cell/radiotherapy , Dental Arch/radiation effects , Dental Arch/surgery , Dental Implantation, Endosseous/methods , Dental Implants , Dental Prosthesis Design , Dental Restoration Failure , Female , Follow-Up Studies , Head and Neck Neoplasms/radiotherapy , Humans , Jaw/radiation effects , Jaw/surgery , Male , Mandible/radiation effects , Mandible/surgery , Maxilla/radiation effects , Maxilla/surgery , Middle Aged , Proportional Hazards Models , Radiotherapy Dosage , Retrospective Studies , Risk Factors , Survival AnalysisABSTRACT
Bone decalcification is a time-consuming process. It takes weeks and preservation of the tissue structure depends on the quality and velocity of the demineralization process. In the present study, a decalcification methodology was adapted using microwaving to accelerate the decalcification of rat bone for electron microscopic analysis. The ultrastructure of the bone decalcified by microwave energy was observed. Wistar rats were perfused with paraformaldehyde and maxillary segments were removed and fixed in glutaraldehyde. Half of specimens were decalcified by conventional treatment with immersion in Warshawsky solution at 4ºC during 45 days, and the other half of specimens were placed into the beaker with 20 mL of the Warshawsky solution in ice bath and thereafter submitted to irradiation in a domestic microwave oven (700 maximum power) during 20 s/350 W/±37ºC. In the first day, the specimens were irradiated 9 times and stored at 40ºC overnight. In the second day, the specimens were irradiated 20 times changing the solution and the ice after each bath. After decalcification, some specimens were postfixed in osmium tetroxide and others in osmium tetroxide and potassium pyroantimonate. The specimens were observed under transmission electron microscopy. The results showed an increase in the decalcification rate in the specimens activated by microwaving and a reduction of total experiment time from 45 days in the conventional method to 48 hours in the microwave-aided method.
A preservação da estrutura de ossos é dependente da qualidade e da velocidade em que ocorre o processo de desmineralização. Neste estudo foi observada a ultraestrutura de maxila de rato descalcificada utilizando microondas. Ratos Wistar sofreram perfusão com paraformaldeído e o segmento de maxila retirado e fixado em glutaraldeído. Após esta etapa algumas amostras foram descalcificadas por imersão em solução de Warshawsky durante 45 dias a 4(0)C. Outras amostras foram submetidas a irradiação por microondas (forno de microondas doméstico 700 Watts de potência), durante 20 s/350 W/ ± 37ºC. No primeiro dia foram realizadas um total de 9 irradiações e os espécimes foram deixadas posteriormente a 4ºC por 12 h na solução descalcificadora sem agitação. No segundo dia, os fragmentos foram submetidos à nova irradiação totalizando 20 banhos, trocando-se a solução e o gelo a cada banho. A seguir algumas amostras foram pós-fixadas com tetróxido de ósmio e outras com tetróxido de ósmio e piroantimonato de potássio. As amostras foram observadas em microscópio eletrônico de transmissão. Os resultados mostraram que o processo de descalcificação ativado por microondas reduziu para 48 h o período de descalcificação, o qual pelo método tradicional ocorre em 45 dias.
Subject(s)
Animals , Rats , Bone and Bones/ultrastructure , Decalcification Technique , Microwaves , Bone Matrix/radiation effects , Bone Matrix/ultrastructure , Bone and Bones/radiation effects , Calcium , Chelating Agents , Cold Temperature , Crystallography , Collagen/radiation effects , Collagen/ultrastructure , Edetic Acid , Fixatives , Glutaral , Microscopy, Electron, Transmission , Maxilla/radiation effects , Maxilla/ultrastructure , Organelles/radiation effects , Organelles/ultrastructure , Osteoclasts/radiation effects , Osteoclasts/ultrastructure , Osteocytes/radiation effects , Osteocytes/ultrastructure , Rats, Wistar , Sodium Hydroxide , Specimen Handling/methods , Time FactorsABSTRACT
A osteorradionecrose é uma das complicaçöes mais importantes no tratamento radioterápico das neoplasias da cabeça e pescoço. Muitos fatores parecem contribuir para o seu aparecimento, sendo que o emprego de dosagens radioterápicas acima de 6.000 CGY e infecçäo säo os mais importantes. O tratamento da osteorradionecrose da maxila baseia-se no combate à infecçäo e higiene oral, sendo ocasionalmente necessária limpeza cirúrgica