Biomedical subjects
Publications and source records attributed to H Reychler.
According to this investigation, antibiotic treatment of odontogenous abcesses should be directed primarily against streptococcus and staphylococcus, even if gram-negative pathogens have apparently increased. The response on the part of streptococcus to antibiotics has not changed essentially during the last five years. Staphylococcus however has developed a resistance to penicillin and ampicillin.
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With a view to the study of the subcellular localization of nucleases, methods ensuring the homogenates. The ribonuclease activity of rat liver is due to the three enzymes with different pH optimun. For acid ribonuclease (pH optimun 5.3), it is possible to avoid interference from the other ribonucleases by performing the incubation at pH 5. Neutral ribonuclease (pH optimum 7.6) is differentiated by relying on its sensitivity to the natural inhibitor from the supernatant of liver homogenate. Comparison of activities before and after pretreatment at 50 degrees C in acid medium permits the specific measurement of alkaline ribonuclease (pH optimum 8.8). The optimal conditions for the determination in liver homogenates of two deoxyribonucleases and of an enzyme acting on polyriboadenylate are also described. The activity of these various nucleases is compared and some of their properties are investigated.
The objective of this research was to evaluate the influence of radiotherapy on the osseointegration of oral implants in a canine model. After the extraction of all mandibular premolars and first and second molars, 11 male beagles were divided into 3 groups. The control group (3 dogs) received no radiation. The second group (4 dogs) was irradiated 4 weeks after implantation. The third group (4 dogs) was irradiated 8 weeks before implantation. Eight implants were placed in each dog, in an alternating pattern: 4 non-submerged ITI Bonefit titanium plasma spray-coated and 4 submerged Steri-Oss hydroxyapatite-coated. The irradiated dogs received 4.3 Gy daily for 10 days. After 6 months of osseointegration, the dogs were sacrificed and each hemimandible was dissected to isolate the implants. Quantification of the extent of the direct bone-implant contact was carried out by scanning electron microscopy backscattered electron images that reproduced each implant in its entirety, using a digitizing table connected to a computer. The results were expressed as a percentage of direct bone-implant contact versus total perimeter accessible to bone. The bone contact percentage for the control group was 87% for Steri-Oss implants and 69% for the ITI Bonefit implants; for the animals irradiated after implantation, the percentages were 82 for Steri-Oss implants and 58 for ITI Bonefit implants; and for the animals irradiated before implantation, the percentages were 62 for Steri-Oss implants and 28 for ITI Bonefit implants. A statistically significant difference appeared between the 2 types of implants (P < .001). A statistically significant difference was also seen between the 3 groups for both types of implants, except between the control group and the group irradiated after implantation (P = .14). This indicates that, overall, the timing of irradiation influences osseointegration. Osseointegration is possible before and after radiotherapy; however, the direct bone-implant contact increased when the implants were placed before irradiation.
This paper describes different mandibular AO-osteosynthesis methods. Because anatomical and biomechanical criteria, the technical aspects of the osteosynthesis may be quite different but they must always take account of the AO principles; only this warrant a primary ossification. The role of the intermaxillary fixation is detailed.
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Explore the source record for details and available documents.
Explore the source record for details and available documents.
Nineteen patients who were treated for oncologic pathology by surgery and radiotherapy (average dose = 57 Gy) received prosthetic reconstruction with 53 implants placed in the residual mandible or maxilla and/or replacement bone graft. Implants were placed within a minimum period of 5 months after radiotherapy. The healing period before placement of the prosthesis also was at least 5 months. Two to six implants were placed as a function of tooth loss and required prosthetic design. Prostheses included both removable and fixed restorations. Two implants were lost as a result of osseointegration failure. Fifteen implants in six patients could not be followed throughout the study because of patient expiration. Patients were followed up to 68 months and for an average of 38 months. No osteoradionecrosis phenomenon was seen in this study. However, caution is urged in placing implants in irradiated bone because of the potential for osteoradionecrosis. Patients should be carefully selected and a strict therapeutic protocol should be followed.