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Biomedical subjects

H Schliephake

Publications and source records attributed to H Schliephake.

At least 37 records · Page 2Linked to original sources
PubMed2000

[In vitro manipulation of primary human osteo-progenitor cells for tissue technological bone production].

The aim of the present study was to evaluate the effect of three different techniques for isolation of human bone-marrow-derived mesenchymal stem cells (MSCs) on the in vitro differentiation of these cells. Furthermore, the use of BMP-2 was assessed and the effect of gene transfer of the BMP-2 gene into these cells was evaluated. Reverse transcription polymerase chain reaction showed that isolation of MSCs by outgrowth from cancellous chips resulted in expression of both osteogenic and chondrogenic markers, while cells cultivated from marrow aspirates exhibited only osteogenic markers. Intramuscular reimplantation of BMP-2-transfected cells in poly-(L/DL 70/30) lactic acid fleeces resulted in formation of mineralized tissue after 8 weeks in athymic rats, while control-transfected cells exhibited matrix synthesis without mineralized tissue after intramuscular reimplantation.

Animals↗
PubMed2000

[Pilot study of controlled liberation of growth factors from polylactide implants].

The aim of the present study was to test polylactic acid material as a controlled release carrier for polypeptide growth factors. Basic fibroblast growth factor (bFGF) was incorporated into DL polylactic acid (PLA) pellets under hyperbaric CO2 pressure in two different ways. (1) Lyophilized bFGF was crushed and mixed with PLA granules, filled into cylindric moulds of 5 x 3 mm, and submitted to hyperbaric CO2 pressure. (2) Lyophilized bFGF was reconstituted in phosphate buffer, mixed with PLA granules, and relyophilized. In vitro assessment of bFGF release from the PLA implants by immunoassay showed that loading of PLA with crushed lyophilized bFGF resulted in a rapid and high release, while loading by solubilized bFGF and relyophilization led to a low and more regular release of the polypeptide growth factor.

Drug Carriers↗
PubMed2000

[In vivo administration of purified supernatant of fetal and postnatal osteoblast cultures: initial results].

With increasing age of an organism, the osseous regenerative potential is reduced. In osteoblast-like cell cultures, cells of older donors that would not proliferate under standard conditions start to proliferate and express a differentiated phenotype when supplemented with the supernatant of fetal osteoblast-like cultures. The aim of this study was an evaluation of the fetal supernatant actions in vivo. Rat calvaria-derived osteoblasts of fetal and 21-day-old donors were isolated enzymatically and cultured. Their osteoblastic phenotype was confirmed by the expression of typical osteoblast synthesis products. The supernatant of the cultures of each age group was collected and pooled. The supernatant was purified by HPLC and concentrated approximately ten times. Additionally, several age-dependent differences within the purified protein fractions were documented by MALDI. After resuspension, the purified supernatant proteins were transferred on a collagen carrier and implanted into critical size defects of the calvaria of adult Wistar rats. In a control group, the collagen carriers were implanted containing isotonic salt solution. After 2, 4, and 8 weeks, a radiographic and histologic analysis of the regeneration process was performed which revealed differences in the progress of mineralization. The methods used in this study might help to identify age-dependent differences regarding the osteoblastic synthesis of osteoanabolic peptides and their impact on the regeneration of osseous defects.

Age Factors↗
PubMed2000

[Effect of glass ceramics on bone regeneration in calvarial defects. Experimental study].

INTRODUCTION: The purpose of this study was to investigate the influence of different compositions of resorbable porous glass ceramics on their performance in calvarial defects. MATERIAL AND METHODS: Full-thickness defects (8.1 mm diameter) were made in the calvaria of 75 adult Sprague-Dawley rats. Pellets of porous glass ceramics were inserted press-fit into 60 defects. Four different materials were implanted into each of 15 animals: (1) glass ceramic with a high relation of calcium to phosphate containing silicate; (2) glass ceramic with a high relation of calcium to phosphate without silicate; (3) glass ceramic with a low relation of calcium to phosphate without silicate; and (4) glass ceramic with a low relation of calcium to phosphate containing silicate. Five implants of each group were evaluated by fluorescence microscopy and light microscopy after 6, 13, and 26 weeks. RESULTS: Those glass ceramics with a high relation of calcium to phosphate showed formation of new bone entering the defect from the margins as soon as 6 weeks postoperatively. After 26 weeks, the formation of new bone reached the center of the defect. In the other glass ceramics, the formation of unmineralized osteoid was visible entering the defect from the margins. No mineralization was seen 26 weeks postoperatively. There was no significant difference between glass ceramics containing silicate and those free of silicate. CONCLUSIONS: Bioresorbable glass ceramics may be of benefit in the treatment of osseous defects without functional loading.

Animals↗
PubMed2000

[Vertical distraction osteogenesis of the alveolar process using a tooth-borne device].

Since the communication of McCarthy et al. in 1992, applications for distraction osteogenesis in the maxillofacial complex have increased enormously. The advantages as compared to conventional reconstructive procedures are missing donor-site morbidity for bone graft harvesting, reduced blood loss and also a gradual gain in the soft tissue envelope. Meanwhile, even the vertical lengthening of the alveolar process has become a clinically reliable method. The case presented illustrates the treatment of a 16-year-old patient who suffered a sporting accident at the age of 7 years, leading to ankylosis of the upper middle incisors with subsequent underdevelopment of the frontal alveolar process. After fabrication of a custom-made distraction device, an osteotomy of the tooth-bearing segment in the upper front was performed and the segment was attached to the distraction device. Bone lengthening was started on the seventh postoperative day at a daily rate of 0.5 mm. The distraction was maintained until closure of the open bite was achieved. On the 22nd day, the segment was fixed using an orthodontic arch wire and the distraction device was removed. A retention period of 6 weeks was maintained until sufficient stability was detectable. Now, 1.5 years after the treatment, the situation is stable with a good consolidation of the bone fragments and a physiologically shaped gingivobuccal sulcus. Lengthening of the alveolar process by vertical distraction osteogenesis using a tooth-borne device may be indicated in certain cases. With this technique a second operation can be avoided and there is less risk of laceration of dental roots by fixation screws.

Adolescent↗
PubMed2000

Soft tissue profile changes after autogenous iliac crest onlay grafting for the extremely atrophic maxilla.

PURPOSE: The aim of this study was to evaluate profile changes in the hard and soft tissues after onlay grafting in the extremely atrophic maxilla. PATIENTS AND METHODS: Onlay grafting using autogenous iliac crest bone grafts was performed in 49 patients (42 females and 7 males) with extreme atrophy of the edentulous maxilla (vertical amount of bone: <6 mm, transverse amount of bone: <5 mm). For the assessment of the changes to the hard and soft tissues, the preoperative and postoperative cephalograms were traced and the cephalometric measuring points (44 skeletal and 25 soft tissue points) were digitalized with the aid of the Dentofacial Planner System. Evaluation of a relationship between soft tissue and hard tissue profile changes was performed by comparing the movement of the skeletal points Sub-ANS and A-point with the shift of the soft tissue point SLS. To determine significant hard tissue and soft tissue changes, the measured values were evaluated using the SPSS program system and examined for statistical significance by use of the Wilcoxon test. RESULTS: An advancement of the bony maxilla profile in the sagittal direction by an average of 2.4 mm (P < .01) was found. The soft tissue profile of the upper lip was moved forward on average by 2.3 mm (P = .0039) at the superior labial sulcus point and by 2.7 mm (P = .0018) at the labrale superius point. The ratio of the soft tissue change to hard tissue change was 0.7:1 (superior labial sulcus: skeletal point sub-ANS) or 0.9:1 (superior labial sulcus: A point). CONCLUSIONS: When planning onlay graft operations, consideration should be given to the functional and aesthetic effects of the profile changes on the upper lip.

Adult↗
PubMed2000

Osseointegration of endodontic endosseous cones: zirconium oxide vs titanium.

OBJECTIVE: The purpose of this investigation was to investigate the osseointegration of zirconium oxide (ZrO(2)) ceramic cones in comparison with that of titanium cones in apicectomy. STUDY DESIGN: To evaluate the bone/implant interface, 20 ZrO(2) cones and 20 titanium cones were inserted into the mandibles of 4 Göttinger minipigs. During the 6-month healing period, intravital polychrome sequence marking was performed. Qualitative light microscopic, fluorescence microscopic, and quantitative histomorphometric assessment was carried out. Differences between continuous histomorphometric measures were tested through use of a 2-way analysis of variance. RESULTS: Light microscopy revealed zones of direct bone contact with the ZrO(2) and titanium surfaces. Fluorescence microscopy revealed remodeling processes directly adjacent to both material surfaces. There was no significant difference in the distances of the fluorescence bands of each fluorescence marker for either the ZrO(2) surfaces or the titanium surfaces. Quantitatively and histomorphometrically, the mean ratio between the total cone/bone contact and the total cone/fibrous tissue contact was 0.95 (SD 1.10) on the titanium surface (n = 38) and 1.47 (SD 1.12) on the ZrO(2) surface (n = 78; P =.02). CONCLUSIONS: The qualitative results show that the biocompatibility of ZrO(2) was similar to that of titanium. The use of ZrO(2) cones for sealing purposes in resected teeth after apicectomy appears to be acceptable.

Analysis of Variance↗
PubMed2000

Guided bone regeneration around endosseous implants using a resorbable membrane vs a PTFE membrane.

The aim of the present experimental pilot study was to assess bone regeneration underneath resorbable barrier membranes vs non-resorbable extended polytetrafluoroethylene (ePTFE) membranes in peri-implant defects. Two implants were inserted into surgically created defects on each side of the mandibles of 6 adult beagle dogs 3 months after extraction of all premolar teeth. One implant on each side was covered with a porous polylactic acid membrane or a ePTFE membrane, respectively, while the second implant served as control. Fluorochrome labelling was administered during the 1st, 5th, 12th and the 18th week. Three animals each were evaluated after 3 and 6 months. Bone regeneration was assessed by measuring the distance from the first fluorochrome label to the level of the regenerated bone immediately adjacent to the implant surface and to the top of the newly formed alveolar contour both on the lingual and buccal side. The increase in bone height was significantly higher compared to the controls under both barrier membranes after 3 months at the top of the alveolar crest but not immediately adjacent to the implant surface. After 6 months, bone height was significantly increased only at the top of the alveolar contour underneath the ePTFE membranes, while bone underneath the polylactic acid membranes showed signs of superficial resorption. It is concluded that guided bone regeneration underneath barrier membranes can restore alveolar bone contour but is not necessarily associated with a higher bone/implant contact. The use of resorbable membranes may be associated with untoward biological effects at later stages, when membrane degradation starts due to degradation products of the polymer material or decreasing membrane stability. Future efforts have to refine the relation between degradation kinetics, membrane porosity and mechanical properties of degradable barrier membranes to improve membrane performance.

Absorbable Implants↗
PubMed2000

Revascularized tissue transfer for the repair of complex midfacial defects in oncologic patients.

PURPOSE: This study reviews the author's experience with revascularized tissue transfer for the repair of complex midfacial defects in oncologic patients. PATIENTS AND METHODS: Fifteen oncologic patients who had received vascularized tissue repair of combined skeletal and soft tissue defects during 1991 to 1999 were reviewed. The mean postoperative interval was 50.2 months. Primary reconstruction was accomplished by vascularized soft tissue repair alone in 1 case, an osteocutaneous scapula graft in 1 case, and by vascularized soft tissue and nonvascularized bone grafts in 3 cases. Secondary reconstruction with nonvascularized bone after vascularized soft tissue transfer was done in 3 cases, and vascularized secondary reconstructions with composite flaps were performed in the remaining 7 cases. Patients were examined for closure of oronasal or oroantral perforations and restoration of midfacial contour. The results were categorized as good, fair, and poor, and were related to the type and timing of the restoration. RESULTS: One flap loss was encountered and one compromised flap was salvaged. Secondary nonvascularized skeletal reconstructions after vascularized soft tissue transfer were susceptible to infectious complications caused by voids, and they did not provide adequate skeletal contour in higher-order defects. Contour restoration was estimated to be good in 9 patients, fair in 3, and poor in 3. Poor results were limited to secondary reconstructions. CONCLUSION: It is concluded that the skeletal repair of the midface frame should be done primarily, as far as possible. If the orbital frame can be preserved, primary repair by vascularized soft tissue alone may be sufficient, with secondary restoration of the alveolar crest with nonvascularized bone grafts. Complex midfacial defects of types IV and V according to Wells and Luce require multistep procedures to accomplish all goals of midfacial reconstruction.

Adult↗
PubMed2000

Revascularized muscle transfer for facial reanimation after long-standing facial paralysis.

The aim of the present study was to evaluate the results of a group of patients who had received free vascularized muscle transfer to the face for the treatment of long-standing facial paralysis. In 15 patients, neurovascular transfer of 16 segments of the gracilis muscle to the cheek was performed for reanimation of oral commissure movement. Voluntary muscle activation was evaluated by electromyography (EMG) and clinical function was assessed both metrically from frontal photographs and by a rating system with 6 categories. Patient satisfaction was explored through a self-administered questionnaire of general health (SF-36 health survey). The average follow-up period was 49.3 months. All patients showed voluntary activation of the grafted muscles in the EMG. Symmetry of the static and dynamic position of the oral commissure at rest and under function was considerably improved. In general, however, there was a tendency for undercorrection particularly in a vertical direction. Under function, the excursion of the oral commissure on the grafted side reached 63.7% and 65.5% of the nonparetic side in vertical and horizontal directions, respectively. Subjective rating of patient well-being showed that the scores were higher than or comparable to those of healthy adults in six of eight areas of evaluation.

Adolescent↗
PubMed2000

Synthesis of CAD/CAM, robotics and biomaterial implant fabrication: single-step reconstruction in computer-aided frontotemporal bone resection.

The preoperative manufacturing of individual skull implants, developed by an interdisciplinary research group at Ruhr-University Bochum, is based on the use of titanium as the most common material for implants at present. Using the existing technology for materials that can be milled or moulded, customized implants may be manufactured as well. The goal of the study was to examine biodegradable materials and to evaluate the practicability of intraoperative instrument navigation and robotics. Data acquisition of an adult sheep's head was performed with helical computer tomography (CT). The data were transferred onto a computer aided design/computer aided manufacturing system (CAD/CAM system), and two complex defects in the frontotemporal skull were designed. Standard individual titanium implants were milled for both of the defects. Additionally, for one of the defects a resection template, as well as a mould for the biodegradable poly(D,L-lactide) (PDLLA) implant, were fabricated by the CAD/CAM system. A surgeon carried out the first bone resection (#1) for the prefabricated titanium implant using the resection template and an oscillating saw. The robot system Stäubli RX90CR, modified for clinical use, carried out the other resection (#2). Both titanium implants and the PDLLA implant were inserted in their respective defects to compare the precision of their fit. A critical comparison of both implant materials and both resection types shows that fabrication of a PDLLA implant and robot resection are already possible. At present, the titanium implant and resection using a template are more convincing due to the higher precision and practicability.

Absorbable Implants↗
PubMed1999

[Masticatory rehabilitation of tumor patients by endosseous implants. 10 year analysis].

A total of 409 implants was inserted into 83 consecutive patients, who had tumor-related intraoral resections of soft tissue and bone. A life table analysis was used to determine the survival rate of the implants placed over a period of 13 years. Log rank tests and a Cox regression analysis were employed to identify relevant effects of surgical parameters on implant survival. A total of 38 implant failures were encountered. Most of the losses (n = 16) occurred during the first year of functional loading. The cumulative, overall survival rate of implants was 56.5%. Previous radiation therapy, insertion into grafted bone or original jaw bone, and insertion into microsurgically revascularized grafts did not significantly affect the survival rates. In the Cox regression, only the timing of implant placement was significantly related to the survival rate in the group of patients with bone grafts (P = 0.0197), with a lower survival rate of 36.2% of primary inserted implants and 67.1% survival in the group with secondary implant placement.

Bone Transplantation↗
PubMed1999

[Endosseous implants for functional masticatory rehabilitation in the extremely atrophied edentulous maxilla].

PURPOSE: The aim of this retrospective study was to evaluate the long-term survival rate of dental implants in edentulous patients suffering from severe atrophy of the alveolar ridges in the upper jaw. PATIENTS AND METHODS: In total, 964 implants were inserted in 140 patients. A total of 481 implants were combined with an osteoplastic augmentation of the maxilla, and 483 implants were inserted directly in the atrophic bone. The success rate was determined using survival analysis, log rank tests and a Cox regression analysis. RESULTS: The overall survival rate for all implants was 42.2% during an observation period of 11 years. Between implants combined with an osteoplasty and implants inserted in local bone tissue there were no significant differences in the survival rate. The survival rate of implants combined with an osteoplasty was significantly reduced in women and in the case of repeated insertion or augmentation. Interestingly, a few of the patients treated with an osteoplasty demonstrated high numbers of individual implant failures. Those patients were postmenopausal women exclusively. Among them there is probably a certain group with a very high risk of implant failures. CONCLUSION: This study shows that oral rehabilitation with osteointegrated implants in patients with severely atrophic alveolar ridges in the upper jaw is still problematic.

Alveolar Bone Loss↗
PubMed1999

[Prosthetic scintigraphic study of healing of implants combined with bone transplantation in extreme atrophy and after tumor resection].

The aim of the present study was to evaluate the healing of onlay grafts to edentulous jaws and after tumor ablation in conjunction with osseointegrated implants using sequential bone scintigraphy and single photon emission computed tomography (SPECT). A total of 24 patients were examined after onlay grafting of extremely atrophic edentulous jaws and after tumor ablation with secondary implant placement 21.4 weeks after grafting. Technetium-99m (MDP) scintigrams were performed immediately after grafting, before and after implant placement, and before abutment connection. Tracer accumulation was assessed semiquantitatively by calculating ratios of count densities between the uptake over the calvaria and over the grafted jaws. There was a significant decrease in tracer uptake during graft healing, which was followed by a significant increase after implant placement and a subsequent decrease during implant healing. In patients with complicated healing, tracer uptake in areas of subsequent graft infection immediately after grafting was significantly lower compared with patients with uneventful healing. These areas also showed a lower increase in tracer accumulation after implant placement due to inferior graft quality, followed by a significant increase of tracer uptake at the time of abutment connection, representing inflammatory peri-implant bone reaction. Sequential bone scintigrams and bone SPECT have the prognostic potential to detect areas of inferior graft revascularization leading to graft infection or failure in the osseointegration of implants. Only bone SPECT allows an exact localization of areas with complicated healing.

Adult↗
PubMed1999

[Complex reconstruction of the area of the maxilla and mid-face after radical tumor surgery].

The esthetic and functional restoration of facial defects is always a daunting challenge. The advent of free vascularized tissue transfers in combination with oral implants enables the surgeon to attain a high level of flexibility in the treatment of such defects. Due to its anatomical properties, the osteocutaneous scapula flap qualifies to a high degree for reconstruction purposes in the midfacial area. From July 1990 to February 1997, reconstruction of complex facial defects after oncologic surgery was performed in 17 patients using free vascularized tissue transfer. In four cases, a free scapula flap was used. Advantages and disadvantages of this technique are illustrated in these patients. Complete oral rehabilitation requires bony continuity of the jaws and stable dentition. To attain this goal, additional grafting procedures are required in most cases when insertion of oral implants is planned. As for the soft tissues, the problem of measuring the amount of tissue needed often leads to an overcorrection, requiring several debulking procedures.

Adult↗
PubMed1999

Comparison of the late results of mandibular reconstruction using nonvascularized or vascularized grafts and dental implants.

PURPOSE: This study evaluates contour restoration in segmental defects of the mandible and the survival rate of endosseous implants placed into these reconstructions. PATIENTS AND METHODS: Forty-four patients with 23 nonvascularized grafts and 21 patients with vascularized bone flaps were included in the study. The lateral and the sagittal extension of the contour of both the mandibular bone and the overlying soft tissues was determined from serial computed tomography (CT) scans in defined planes through the reconstructed mandible. The success rate of dental implants was determined by a life-table analysis. RESULTS: Average lateral deviation of the reconstructed side from the nonreconstructed side was 4.3 mm (nonvascularized grafts) and 5.6 mm (vascularized grafts). The soft tissue contour followed the skeletal contour quite closely, with slightly smaller degrees of deviation. Asymmetry was greatest in the area of the horizontal ramus. In some cases, skeletal deviation was intentionally produced to compensate for a soft tissue deficit on the reconstructed side. However, in some cases, a major deviation of bone contour was associated with considerable deviation of the soft tissue contour (maximum, 10.5 mm). The cumulative implant success rate was 100% after 5 years and 60.3% after 10 years. None of the seven implant failures accounted for prosthetic failure. CONCLUSIONS: Although there are minor differences, both nonvascularized and revascularized grafts allow for satisfactory contour restoration in segmental reconstructions of the mandible. Implants placed into these grafts provide a reliable basis for dental rehabilitation.

Analysis of Variance↗
PubMed1999

Microvascular reconstruction of the skull base: indications and procedures.

PURPOSE: The aim of the current study was to review the use of free tissue transfer for reconstruction of the skull base and for coverage of intracranial contents. PATIENTS AND METHODS: From 1990 until 1996, revascularized flaps were transferred to the skull and the skull base in 11 patients in whom intracranial/extracranial resection of tumors of the skull base was performed in cooperation with the Department of Neurosurgery. The defects resulted from removal of squamous cell carcinomas (n = 4), basal cell carcinomas (n = 4), malignant melanoma, malignant schwannoma, and malignant meningioma. Defect repair was accomplished by revascularized transfer of latissimus dorsi muscle flaps in seven cases and rectus abdominis flaps and forearm flaps in two cases each. In five patients with extensive intracranial tumor spread, reconstruction was performed for palliative reasons. RESULTS: A safe soft tissue closure of the intracranial and intradural space was achieved in all patients, whereas the contour of the facial skull and the neurocranium was satisfactorily restored at the same time. By using the entire length of the grafted muscle, the vascular pedicle could be positioned next to the external carotid artery and conveniently connected to the cervical vessels. The mean survival time of the patients with palliative treatment was 8.4 months, with an average duration of hospital stay of 24.5 days. CONCLUSIONS: Despite the increased surgical effort of revascularized tissue transfer, microvascular reconstruction of large skull base defects appears to be justified, even as a palliative measure.

Adolescent↗