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Biomedical subjects

J Reuther

Publications and source records attributed to J Reuther.

At least 37 records · Page 2Linked to original sources
PubMed1996

[Treatment outcome and complications of surgical and conservative management of mandibular fractures].

Retrospective analysis of 712 patients with 1166 mandibular fractures and follow up-study of 374 patients with 593 fractures was performed for discrimination of differences in wound- and bone-healing as well as late results between operative and conservative fracture treatment. 46.1% (328) of all patients have been treated conservatively, 53.9% (384) have been treated by operation. The follow up was performed on 255 patients with operative fracture treatment and 119 patients with conservative treatment. In 3.0% of the operatively treated patients bacterial infections occurred, in comparison to 8.7% of conservatively treated patients. From the viewpoint of functional aspects, such as occlusion, articulation and mandibular movement as well as radiological signs in the fractured region patients after operative treatment have shown partly significantly better results during the follow up compared to the group of conservatively treated patients. Neurological testings of inferior alveolar nerve and mental nerve have shown significantly better results in the group of conservatively treated patients. Since the functional results are much better after operative treatment, osteosynthesis with miniplates should be performed if there are no contraindications. The more precise reconstruction and stabilization of the fragments shortens time of hospitalization and leads to sooner functionality of the mandible.

Bone Plates↗
PubMed1995

Repair of human skull defects using osteoinductive bone alloimplants.

To estimate the efficacy of cranioplasty in clinical practice, autolyzed, antigen-extracted, allogenic (AAA) bone was prepared from cortical bones of human organ donors. AAA bone implants consisted of completely demineralized bone powder, completely demineralized pliable bone chips, surface-demineralized bone chips with pliable crevices, surface-demineralized rigid bone chips, or combinations thereof. 21 patients received AAA bone cranioplasties and were followed-up for between 12 and 58 months (average: 29 months). No infection or rejection of any of the AAA bone implants occurred. X-ray assessments as well as bone scintigraphies revealed osseous integration and remodelling of the AAA bone implants with minimal resorption, with the exception of completely demineralized AAA bone chips which showed partial resorption (2 cases). However, the partial resorption of completely demineralized AAA bone chips ceased after the implants had been remodelled. In 4 cases, the osteosynthesis material was removed between 10 and 18 months after the cranioplasty. In another case, a re-entry was necessary because of recurrence of an intracranial tumor. All of these five AAA bone reconstructions showed bleeding surfaces and osseous consolidations at the time of re-entry. A bone biopsy taken from one of these cranioplasties showed osteoinduction on the surface of the AAA bone implants. This first clinical review of cranial reconstructions using osteoinductive AAA bone implants emphasizes the therapeutical application of AAA bone for cranioplasty. Large AAA bone chips from human skull bones facilitate the reproduction of the skull's convexity especially when combined with preoperative stereolithography-based planning.

Adolescent↗
PubMed1995

[Comparative studies with apicoectomy using various surgical techniques and filling materials].

Follow-up examinations were made retrospectively on 799 apicoectomized teeth from a group of patients with a total of 3,524 apicectomies, the mean postoperative interval of observation being 4.2 years. An intraoperatively orthograde root-canal filling was performed in 51.3%, an intraoperatively retrograde in 23.7% and a preoperative filling in 25.0% of the patients. Apart from 126 teeth that had already been extracted, a further 160 teeth had been clinically and/or radiologically conspicuous, so that a total of 286 failures was to be recorded. The dentally related success graphs computed according to Kaplan and Meier (1958) showed a significantly worse success probability for the preoperative filling compared to the two other techniques. With regard to the different materials employed in orthograde application, the silver filling had a higher and the guttapercha filling a less favourable success quota compared to a titanium filling. Moreover, in the retrograde method, amalgam resulted in a significantly higher success probability than glass ionomer cement. With an attendant cyst there was a significantly improved success quota over apical parodontitis or a renewed operation. With regard to the localization of apicectomies, maxillary front teeth attained the highest success rate. The present results point unequivocally to an unfavourable outcome after preoperative endodontics and underscore the good prognosis of an intraoperatively orthograde filling. Due to the fact that biocompatibility is in the forefront today, time-tested materials, such as silver and amalgam, are clearly being used less.

Adult↗
PubMed1994

Poly(L-lactide): a long-term degradation study in vivo. Part II: Physico-mechanical behaviour of implants.

Three different poly(L-lactide) rods (25 x 3 x 2 mm) were produced either by injection moulding or machined out of a solid as-polymerized polylactide block and were implanted for 1-116 months into the dorsal muscle of rats. After recovery, the polylactide specimens were carefully cleaned, dried, photographed and weighed. Bending strength and Young's modulus of elasticity were determined. The surfaces of the broken rods were examined by scanning electron microscopy. Block polylactide samples initially looked milky. They became friable and broke into white or brownish fragments during the implantation period, whereas total disintegration could not be observed. Electron scanning microscopy revealed a porous surface with crystalline elements persisting for the whole time. Mechanical stability fell from 127 +/- 3 MPa at implantation time to about half after 3 wk (61 +/- 4 MPa) and about a quarter (32 +/- 4 MPa) after 6 wk. Both injection-moulded polyactides (A1 and A2) were clear and transparent initially. After implantation they gradually became whitish, fragmented after about 64 wk and disintegrated 90 wk later into small parts and powder. Electron scanning microscopy at first showed a homogeneous surface. A kind of cortex developed after about 4 wk and deep cracks ran through the rod after 32 wk. Round pores of 1.5-10 microns diameter developed after 1 yr of implantation. Bending strengths were 130 +/- 8 MPa (A1) and 115 +/- 14 MPa (A2); these remained nearly stable over about 12 wk, then declined linearly. Although a higher initial mechanical strength is desirable for use in osteosynthetic devices, mechanical stability of amorphous injection-moulded polylactides over the first 12 wk and total disintegration thereafter approaches the requirements for their use as a material for osteosynthesis.

Animals↗
PubMed1994

IgG monoclonal antibodies that inhibit osteoinductivity of human bone matrix-derived proteins (hBMP/NCP).

Monoclonal hBMP/NCP (human bone morphogenetic protein and associated noncollagenous proteins) antibodies of the IgG class were produced. In vitro, 12 of 19 hBMP/NCP antibodies showed functional inhibition of hBMP/NCP-induced chondroneogenesis in a neonatal muscle tissue assay. Inducing factors were characterized by their inhibiting antibodies with immunoblotting. Several peptide factors seem to be involved in the cascade of induced chondro- and osteogenesis.

Animals↗
PubMed1994

Preoperative radiochemotherapy and radical surgery in comparison with radical surgery alone. A prospective, multicentric, randomized DOSAK study of advanced squamous cell carcinoma of the oral cavity and the oropharynx (a 3-year follow-up).

A multicentric, randomized study of squamous cell carcinoma (SCC) of the oral cavity and the oropharynx has been undertaken by DOSAK. The results after radical surgery alone have been compared with the results of combined preoperative radiochemotherapy followed by radical surgery. Patients with primary (biopsy proven) SCC of the oral cavity or the oropharynx with tumor nodes metastasis (TNM) stages T2-4, N0-3, M0 were included in the study. A total of 141 patients were treated by radical surgery alone, whereas 127 patients were treated by radical surgery preceded by preoperative radiochemotherapy. The preoperative treatment consisted of conventionally fractioned irradiation on the primary and the regional lymph nodes with a total dose of 36 Gy (5 x 2 Gy per week) and low-dose cisplatin chemotherapy with 5 x 12.5 mg cisplatin per m2 of body surface during the first week of treatment. Radical surgery according to the DOSAK definitions (DOSAK, 1982) was performed after a delay of 10-14 days. During the follow-up period, 28.2% of all patients suffered from locoregional recurrence, and 27.2% of the patients died. The percentages were higher after radical surgery alone for locoregional recurrence (31% and 15.6%) and for death (28% and 18.6%). The life-table analysis showed improved survival rates of 4.5% after 1 year and 8.3% after 2 years in the group of patients treated with combined therapy. The demonstrated improvement appeared to be significant with the Gehan-Wilcoxon test as well as with the log rank test below a P value of 5%.

Carcinoma, Squamous Cell↗
PubMed1994

The use of the 'de-epithelialized' scapular flap for soft tissue augmentation--a case report.

For the augmentation of maxillo-facial soft tissue deficiencies, microsurgical 'pure' fat transplants have proven effective. In this paper, we present the 'de-epithelialized' scapular flap and discuss its significance in comparison with other microvascular fat transfers. Consistency of transplant vessels and minimal dependence of volume on the overall nutritional condition are its specific advantages. The transplant can be securely fixed at the retained corium.

Adipose Tissue↗
PubMed1994

[Temporomandibular joint reconstruction with free rib and iliac crest bone transplants].

From 1981-1992 we reconstructed the temporomandibular joint in 42 patients. In 33 cases reconstruction followed tumour resection of the mandible, almost advanced squamous cell carcinomas of the retromolar region. Primary reconstruction was made by an alloplastic condylar prosthesis combined with a plate for mandibular reconstruction. 2 years after first treatment secondary reconstruction followed by transplantation of a free iliac bone graft. In some cases a new condylus was formed using autogenous rib graft or allogenous cartilage. Result was adequate and painless oral aperture. For reconstruction after ankylosis, arthrosis or arthritis we use a autogenous costochondral graft. 9 patients received such treatment. In 5 or 9 cases with severe ankylosis we prefer a two-time-approach: after resection of the ankylosis we first fix an alloplastic implant (Palacos) at the skull base for distraction of the scar. Two or three years later we do secondary reconstruction with a costochondral graft. The final result strongly depends on functional postoperative treatment and the compliance of the patient.

Adolescent↗
PubMed1993

Poly(L-lactide): a long-term degradation study in vivo. I. Biological results.

Three poly(L-lactides) with different molecular weights were synthesized. Small blocks (3 x 3 x 2 mm) and rods (25 x 3 x 2 mm) were produced either by injection moulding (amorphous parts, Mvis 200,000 and 120,000, respectively) or machined out of a solid aspolymerized polylactide block (crystalline parts, Mvis 429,000) and implanted into the dorsal muscle of rats. After 1 to 116 wk the rats were killed and the implants were recovered. Histological preparation was carried out using the cutting-grinding technique. All three polylactides had incorporated well, forming a collagenous fibrous layer. Crystalline block polylactide remained stable in form and structure over the whole observation period. Amorphous injection-moulded specimens developed a rough surface within weeks, then deep resorptive lacunae after ca. 1 yr and became totally degraded (Mvis 120,000) or nearly totally degraded (Mvis 200,000) after 2 yr. This velocity of biodegradation seems to meet the requirements for an absorbable material for osteosynthesis. Long-term implantation into rodents brings the problem of foreign-body tumorigenesis independent of the chemical nature of implants (the Oppenheimer effect). Observations in this study and in the literature are discussed.

Animals↗
PubMed1993

Osteoinductive, morphologic, and biomechanical properties of autolyzed, antigen-extracted, allogeneic human bone.

Autolyzed, antigen-extracted, allogeneic (AAA) bone was prepared from human cortical bone and its morphologic, biomechanical, and osteoinductive properties were compared with untreated (frozen) as well as lyophilized human bone. Scanning electron microscopy revealed removal of inorganic calcium phosphates and persistence of shrunken collagen fibrils on the surface of AAA bone matrix. Biomechanical testing of differently prepared bone samples showed that lyophilization increased both the modulus of elasticity (P < .00001) and the compressive strength (P < .00001). Depending on the depth of decalcification in the preparation of AAA bone, both measured values decreased in rehydrated AAA bone compared with untreated bone (P < .00001). Completely demineralized and rehydrated AAA bone was soft, flexible, and showed very little compressive strength. Differences in biomechanical behavior between samples drilled longitudinally or perpendicularly to the diaphyseal bone axis were observed. Xenogeneic human bone samples were implanted in muscle pouches of Sprague-Dawley rats for 6 weeks. AAA bone implants showed chondrogenesis and osteogenesis in 50% of the cases, while untreated or lyophilized bone implants induced no new cartilage or bone formation. As decalcification exposed xenogeneic organic matrix components, AAA bone implants provoked the highest inflammatory reaction. When AAA bone samples were implanted in immunosuppressed rats, the inflammatory reaction was suppressed and 94% of the implants showed endochondral bone formation. The chondroinductivity of the bone samples also was tested in vitro using neonatal rat muscle tissue to avoid interference with inflammatory cells and secreted cytokines. In this assay, 68% of AAA bone samples induced chondroneogenesis, while untreated as well as lyophilized bone samples failed to induce any cartilage formation. The results clearly demonstrate that AAA bone has osteoinductive properties. Biomechanical stability of AAA bone implants depends on the degree of demineralization. Thus, they can be prepared in an appropriate manner for different indications in oral and maxillofacial surgery.

Animals↗