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Biomedical subjects

E Munting

Publications and source records attributed to E Munting.

30 records · Page 2Linked to original sources
PubMed1989

Calcium phosphate cements: action of setting regulators on the properties of the beta-tricalcium phosphate-monocalcium phosphate cements.

Various additives were tested as setting retarders of the beta-tricalcium phosphate-monocalcium phosphate monohydrate (beta-TCP-MCPM) cements. Calcium pyrophosphate (CPP), calcium sulphate dihydrate (CSD) and calcium sulphate hemihydrate (CSH) were found to increase the setting time from 30 s to about 10 min. Moreover, the use of CSH resulted in a marked increase of the final diametral strength of the cement, which could be raised from 1 MPa to about 3 MPa. The best results were obtained when CSH and CPP were added together to the cement, while the addition of CSD and CPP alone only retarded the setting, without improving the final strength. A particular cement composition (64 wt% beta-TCP, 16 wt% MCPM, 15 wt% CSH and 5 wt% CPP), selected for its optimum final strength, was aged in vitro for 8 d at 37 degrees C in saline solution (0.9 wt% NaCl in water). After a moderate decrease, the diametral strength of the specimen was found to level off at about 60% of its initial value (3.2 MPa), for ageing times beyond 1 d. This behaviour has been ascribed to the progressive dissolution of the CSD fraction of the hardened cement, compensated by the crystallization of further amounts of DCPD.

Bone Cements↗
PubMed1989

Prediction of recurrence in the treatment of Dupuytren's disease: evaluation of a histologic classification.

Histologic staging of Dupuytren's lesions into three types is proposed: a proliferative type with high cellularity and mitosis, a fibrocellular type characterized by the presence of a reticulin network, and a fibrous type with few cells. Sixty-three patients (77 hands) who had selective fasciectomy as a primary procedure and whose histologic specimen was available were clinically reviewed for disease recurrence and extension. Twenty-two hands (29%) were free of disease; twenty-five (32%) were free from recurrence but showed an extension, and thirty (39%) had a recurrence. This histologic classification seems to have a prognostic value because the recurrence rate is higher in type I (70%) and lower in type III (18%). The risk of extension did not correlate with the histologic type.

Adult↗
PubMed1989

[Lyophilized homologous bone grafts in middle ear surgery: new perspectives].

The authors share their experience of the use of allografts in the reconstruction of the tympano-ossicular chain. The implants were cut from the cortical substance of the long bone in patients deceased for a maximum of six hours; the donors were tested for syphilis, hepatitis, AIDS, systemic diseases or a neoplasm. These bone allografts were cut to size, degreased, demineralized, frozen and then lyophilized in order to be presented to the surgeon in a sterile container (Bone Bank). The implants were all tolerated well. The anatomical results were satisfactory. Optical microscopic studies showed that the implant was: a) covered with mucosa, b) full of osteoblasts and c) the site of a bone neoformation. Experimental research is currently underway in order to perfect the implant preparation methodology.

Bone Transplantation↗
PubMed1988

Massive bone allografts in large skeletal defects after tumor surgery: a clinical and microradiographic evaluation.

Massive deep-frozen bone allografts were implanted in 13 patients after en bloc tumor resection. Patients were followed up for 14 months to 17 years. Most of the reconstructive procedures included a segmental bone allograft with knee or ankle fusion. Graft infections were the most critical complications in regard to the end results, finally requiring amputation in two cases. There were three stress fractures; two of which were successfully treated without further complication. Graft incorporation was assessed by bone scintimetry in four cases. Isotope uptake by the center of the graft was found to be superior to control bone segments at only 15 years after surgery. Two recovered allograft specimens were available for a microradiographic study. Creeping substitution was a very slow process, initiated at the outer surface of the graft and characterized at 2-3 years after implantation by large, incompletely filled osteons. The present investigation demonstrates that massive bone allografts are very slowly revascularized and are intimately anchored by the host bone. Provided that tumor control is effective and graft infection is avoided, reconstructive surgery with massive bone allografts represents a successful alternative to prosthetic implants in young adult with a long life expectancy.

Adolescent↗
PubMed1988

Effect of sterilization on osteoinduction. Comparison of five methods in demineralized rat bone.

The aim of this study was to find a safe, effective sterilization method that does not destroy the bone-inductive capacity of demineralized bone implants. Five sterilizing agents were tested in rats. Implants procured and processed under sterile conditions served as controls. New bone formation was evaluated by determining dry weight, calcium content, and Sr-85 incorporation of the induced ossicles. Glutaraldehyde solution, formaldehyde gas, and ethylene oxide destroyed almost all the bone-inductive capacity. Irradiation by 2.5 Mrads Co-60 resulted in a loss of about half of the inductive capacity. Merthiolate (0.18 per cent) was the only sterilizing agent that did not reduce the bone-inductive capacity of the demineralized implants. Because merthiolate is not sporicidal, gamma irradiation appears to be the most appropriate sterilizing agent for demineralized bone in clinical use.

Animals↗
PubMed1986

Comparative study of the clinical results obtained by means of Plastipore and ceramic ossicular prosthesis and bone allografts.

We present a comparative study of the clinical and audiologic results obtained by means of Plastipore and ceramic ossicular prostheses and bone allografts in reconstructive middle ear surgery. We stress the excellent tolerance for ceramic and bone allografts in comparison to Plastipore. Functionally, the best results were obtained with partial prostheses using bone allografts and with total ceramic ossicular prostheses. Air-bone gaps less than 10 dB (37%) and 20 dB (69%) were achieved in patients with partial prostheses; in patients with total prostheses, 38% had an air-bone gap of less than 10 dB and 62% of less than 20 dB.

Biocompatible Materials↗
PubMed1985

The osteoinductive capacity of differently HCl-decalcified bone alloimplants.

Three procedures to obtain bone inductive implants were tested heterotopically in 3-month-old allogeneic rats: 1) antigen-extracted HCl-decalcified at 4 degrees C, autolysed implant (AAA bone); 2) HCl-decalcified implant at 4 degrees C; 3) HCl-decalcified implant at room temperature. Each type of implant was either deep-frozen at -35 degrees C for at least 2 months or immediately freeze-dried. The bone inductive capacity of the differently HCl-decalcified cortical bone implant was evaluated at 2 months by isotopic strontium incorporation and by ash-weight measurements. Bone HCl-decalcification alone, either at 4 degrees C or at room temperature, gave a higher new bone yield than the freeze-dried AAA bone. The type or short-term preservation technique had no effect on the osteoinductive capacity of either of the differently treated implants, AAA bone expected.

Animals↗
PubMedDate not supplied

Implants placed in an irradiated dog mandible: a morphometric analysis.

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.

Animals↗