Biomedical subjects

Günter Lauer

Publications and source records attributed to Günter Lauer.

13 recordsLinked to original sources

PubMed2006

Bone regeneration after enucleation of mandibular cysts: comparing autogenous grafts from tissue-engineered bone and iliac bone.

OBJECTIVE: The aim of this study was to compare bone regeneration after grafting enucleated mandibular cyst cavities using either autogenous osteoblasts cultured on a biomaterial or autogenous spongiose iliac bone. STUDY DESIGN: Twenty patients with 22 mandibular cysts were assessed. Eleven cysts were filled in with tissue-engineered bone (autogenous osteblasts cultured on demineralized bone matrix Osteovit) and 11 with spongiose iliac bone as controls. Panoramic radiographs were taken preoperatively, immediately postoperatively, and 3, 6, and 12 months after surgery. Radiolucency was computer analyzed using gray-level histograms. RESULTS: In both groups bone regeneration took place in a similar fashion. After 3 and 6 months there were few differences in bone density between the groups. However, in radiographic controls after 12 months ossification was considerably stronger in cysts grafted with tissue-engineered bone. CONCLUSION: These results advocate for the clinical application of tissue-engineered bone as an alternative viable filling material for cysts.

Adolescent↗

PubMed2006

[Secondary midfacial reconstruction using different surgical techniques and computer assisted surgery].

AIM: Aim of this retrospective study was to assess the outcome after secondary midfacial reconstruction using different operation techniques and computer assisted surgery. Functional and aesthetic aspects as well as experiences are reported. PATIENTS AND METHODS: 18 patients were assessed for enophthalmos, diplopia, and aesthetics during a follow-up period of up to 2.5 years. RESULTS: In 40% of the patients several techniques for soft and hard tissue reconstruction were used. In 5 of the 9 patients diplopia was improved; in 4 patients there was no change. A significant enophthalmos was corrected in 8 out of 12 patients. After additional surgery 6 patients had a good aesthetic result, 7 a satisfactory and 5 a poor. CONCLUSION: For secondary midfacial reconstruction often a combination of different surgical techniques is necessary. Bony asymmetries and enophthalmos were successfully corrected, however, functional and aesthetic impairment due to bad soft tissue condition are difficult to correct. Computer assisted surgery is helpful for dissection within the orbit, for graft placement, and for positioning of osteotomized segments.

Adolescent↗

PubMed2006

Efficacy of computer-assited surgery in secondary orbital reconstruction.

PURPOSE: In this study the efficacy of computer-assisted surgery (CAS) used for secondary orbital reconstruction after midfacial fractures was evaluated, comparing the clinical outcome with that after conventional surgery (CS). Special consideration was given to whether CAS can reduce the number of secondary corrections. PATIENTS AND METHODS: Twenty consecutive patients (24 orbits; 12 in each group) were assessed for enophthalmos, diplopia, and aesthetics during a follow-up period of up to 3 years. RESULTS: After CAS, enophthalmos was fully corrected in 8 of 11 orbits but after CS in only 6 of 10 orbits. Improvement of diplopia was achieved in 1 of 7 (CAS) and in 3 of 4 (CS) patients. The aesthetic result after secondary reconstruction and additional surgery was better in the CAS group. Additional surgery to correct bony structures was only necessary in 3 patients of the CS group. Additional soft tissue surgery was necessary in both groups. CONCLUSION: CAS can improve the clinical outcome of reconstructive bone surgery reducing the amount of additional hard tissue procedures. It was helpful during dissection of the scarred orbital tissue and placement of a graft. However, it had no impact on soft tissue correction especially with respect to function.

Adolescent↗

PubMed2006

Ectopic bone formation in nude rats using human osteoblasts seeded poly(3)hydroxybutyrate embroidery and hydroxyapatite-collagen tapes constructs.

PURPOSE: The aim of this study was to evaluate the ectopic bone formation using tissue engineered cell-seeded constructs with two different scaffolds and primary human maxillary osteoblasts in nude rats over an implantation period of up to 96 days. MATERIAL AND METHODS: Collagen I-coated Poly(3)hydroxybutyrate (PHB) embroidery and hydroxyapatite (HAP) collagen tapes were seeded with primary human maxillary osteoblasts (hOB) and implanted into athymic rnu/run rats. A total of 72 implants were placed into the back muscles of 18 rats. 24, 48 and 96 days after implantation, histological and histomorphometric analyses were made. The osteoblastic character of the cells was confirmed by immunocytochemistry and RT-PCR for osteocalcin. RESULTS: Histological analysis demonstrated that all cell-seeded constructs induced ectopic bone formation after 24, 48 and 96 days of implantation. There was more mineralized tissue in PHB constructs than in HAP-collagen tapes (at day 24; p < 0.05). Bone formation decreased with the increasing length of the implantation period. Osteocalcin expression verified the osteoblastic character of the cell-seeded constructs after implantation time. No bone formation and no osteocalcin expression were found in the control groups. CONCLUSIONS: Cell-seeded constructs either with PHB embroidery or HAP-collagen tapes can induce ectopic bone formation. However, the amount of bone formed decreased with increasing length of implantation.

Animals↗

PubMed2006

Change of mRNA amount of myosin heavy chain in masseter muscle after orthognathic surgery of patients with malocclusion.

INTRODUCTION: Surgical correction of malocclusion changes the force to moment ratio of masticatory muscles inserting at the mandible caused by shortening, lengthening and rotation of the bone following osteotomy. During muscle adaptation the expression of mRNA for the myosin heavy chain (MyHC) of type I and type II fibres may be changed. MATERIAL AND METHODS: The adaptation of the masseter muscle was investigated at the mRNA level in 10 patients 6 months after orthognathic surgery in the mandible. The competitive polymerase chain reaction (cPCR) is a suitable method for quantification of MyHC mRNA. For application of this minimal invasive method an amount of 35 mg muscle tissue was sufficient. RESULTS: 6 month postoperatively there was a deficiency of about 87% of MyHC mRNA for fibre type I and II in both groups of patients. The deficiency in patients with mesial position of the mandible was higher but not significant different to patients with distal malocclusion. CONCLUSION: Patients should use the postoperative interval for training their masticatory muscles. This improves the stability of treatment result and prevents relapse.

Adult↗

PubMed2006

Influence of Cyclosporin A on human gingival keratinocytes in vitro.

PURPOSE: Gingival hyperplasia is a well known side effect of Cyclosporine A therapy. The aetiology of this is not totally understood and there is debate whether it is hyperplasia of the gingival epithelium or of the submucosal connective tissue, or both, and what roles play factors like age and gender of the patients, duration and dosage of the drug. MATERIAL AND METHODS: The influence of different Cyclosporine A concentrations (10(-6) g/ml; 5 x 10(-7) g/ml; 10(-9) g/ml) and of no medication (controls) on growth and proliferation of cultured human gingival keratinocytes was investigated after a culture period of 3, 6 and 9 days. Cell proliferation was assessed by counting anti Ki-67 stained nuclei, cell growth by counting total number of nuclei and by the EZ4U-assay. RESULTS: There was no significant correlation of the cell proliferation rate and cellular growth with either gender (p > 0.568) or duration of medication (p > 0.876); but Cyclosporine A concentration showed a highly significant influence on cellular growth (p = 0.0001). Inhibition of cell growth was dependent on drug dosage, but a low concentration of 10(-9) g/ml even stimulated cell growth. CONCLUSIONS: There is evidence that Cyclosporine A in low concentrations (10(-9) g/ml as applied in long-term therapy) stimulates gingival keratinocyte growth and therefore might be related to hyperplasia of the gingiva. However, high Cyclosporine A concentrations may inhibit cell growths and factors like gender of the patient did not show any influence in-vitro.

Adolescent↗

PubMed2006

Clinical application of tissue-engineered transplants. Part I: mucosa.

OBJECTIVES: The study series aims at testing the feasibility of the clinical application of tissue-engineered oral mucosa. The preliminary results were gathered over a period varying from 6 months to 12 years depending on the surgical method. METHODS: Tissue-engineered oral mucosa was used to cover defects in various surgical procedures like vestibuloplasty (n=42), freeing of the tongue (n=10), prelaminating the radial flap (n=5) and reconstruction of the urethra (n=16). In all interventions small samples of oral mucosa were harvested, cut into small pieces, resuspended in culture medium and seeded into a culture flask. Cultured keratinocytes were transferred onto membranes which then were used to cover mucosal defects in the oral cavity. RESULTS: To gain a graft of 15 cm(2) size a mucosa biopsy of 4-8 mm(2) and 40 ml autologous patients serum is needed. Tissue-engineered oral mucosa was applied successfully in all four surgical methods. Six months after transplantation a regular epithelial layering with a histological delimitation of the stratum, epithelial crest and a strong basal membrane appeared. According to the reception site the tissue engineered oral mucosa differentiated in several ways. CONCLUSION: Tissue-engineered oral mucosa fulfils the requirements for clinical routine. With view to healing time and outcome it does not appear to be superior to regular harvested oral mucosa transplants. Because of a smaller harvesting defect and primary wound closure at the actual operation site the patients' convenience is increased. Thus this method reduces morbidity and advances the quality of life.

Aged↗

PubMed2006

A complex therapy for treatment of frontoethmoidal meningoencephalocele in a developing third world country: neurosurgical aspects.

OBJECT: Meningoencephaloceles are congenital malformations that have a high incidence in the population of Southeast Asia. Frontoethmoidal meningoencephaloceles, the most common variety, require surgical treatment. The authors combined neurosurgical and craniofacial approaches for the development of a simple technique that corrects this type of meningoencephalocele in a one-step procedure that has not been discussed in the literature previously. METHODS: In three visits of approximately 1 week each, 30 patients suffering from a frontoethmoidal meningoencephalocele underwent surgery successfully at the Rose Charities Surgical Rehabilitation Center, Kien Khleang, Phnom Penh, Cambodia. To the authors' knowledge, this is the first reported series of operations in this geographical region to treat meningoencephaloceles at a relatively primitive surgical center. Difficulties faced in this series included tropical conditions, problems ensuring sterility, and limited technical support. CONCLUSIONS: The authors present the neurosurgical highlights and the outcomes in this series of patients. The single approach, via a bicoronal skin incision and small frontobasal trepanation, facilitates closure of the frontal skull defect and resection of the meningoencephalocele (including its extension into the facial area), as well as a satisfactory, one-step correction of the nasal skeleton and telecanthus.

Adolescent↗

PubMed2005

Comparison of the predicted surgical results following virtual planning with those actually achieved following bimaxillary operation of dysgnathia.

AIM: To simulate the surgery of dysgnathia, several forms of computer software allowing two-dimensional 'virtual' planning are frequently used. However, in many cases it is not possible to transfer the virtual plan accurately to the surgical site. It is the purpose of this study to find the errors likely to occur when transferring the data. METHODS: In 22 bimaxillary osteotomies for dysgnathia, the results of preoperative planning were compared with the surgical outcomes. The programme WinCeph 4.19 (Compudent) was used for cephalometric analyses and simulation of the operations. RESULTS: Six major skeletal parameters were evaluated when comparing both the planned and the actual outcome, and the following results were recorded: Delta-SNA 1.53 degrees (+/-1.20), Delta-SNB 1.67 degrees (+/-1.29), Delta-ANB 1.62 degrees (+/-1.47), Delta-NL-NSL 3.9 degrees (+/-2.30), Delta-ML-NSL 3.6 degrees (+/-3.7) and Delta-ArGoMe 6.1 degrees (+/-4.6). CONCLUSION: It was anticipated that the most important differences between planned and surgical outcomes were found to be in the vertical changes. Planning and data transfer was comparatively accurate with regard to sagittal data. Apart from several mechanical methods for data transfer, systems using navigation are therefore being discussed and used increasingly. They ensure accurate data transfer to the surgical site.

Cephalometry↗

PubMed2005

In vitro growth and differentiation of osteoblast-like cells on hydroxyapatite ceramic granule calcified from red algae.

PURPOSE: The purpose of this study was to analyze the interaction between osteoblast-like cells isolated from mandibular bone and hydroxyapatite ceramic bone substitute obtained from calcified red algae to assess the growth and differentiation of adherent cells on this biomaterial. MATERIALS AND METHODS: The macroporous ceramic material C GRAFT/Algipore (The Clinician's Preference LLC, Golden, CO) is composed of 100% hydroxyapatite and possesses specific mechanical and physiochemical properties. Osteoblast-like cells were seeded on 200 mg of biomaterial and cultured for 6 and 21 days under osteogenic differentiation conditions. Specific alkaline phosphatase activity, DNA, and protein content of the proliferating cells were analyzed. The morphology of the cells in contact with the biomaterial was examined by scanning electron microscopy. The osteoblastic phenotype of the cells was confirmed by analysis of the expression of bone-specific genes (osteocalcin, osteopontin and collagen type I) by semi-quantitative reverse transcriptase polymerase chain reaction. RESULTS: The DNA and protein content increased over the culture period. Scanning electron microscopy showed cells spreading on the surface of the biomaterials, covering the macropores, and colonizing the depth of the particles. The analysis of the expression patterns of bone-related genes confirmed the osteoblastic phenotype of the cultured cells. CONCLUSION: The results of this study showed that hydroxyapatite ceramic bone substitute obtained from calcified red algae support the proliferation and differentiation of human osteoblast-like cells on its surface in vitro and might be suitable for use as scaffolds in tissue engineering strategies in vivo.

Bone Substitutes↗

PubMed2003

Analysis of complications in fractures of the mandibular angle--a study with finite element computation and evaluation of data of 277 patients.

AIM: The purpose of this study was to compute the load on different osteosynthesis plates in a simplified model using finite element analysis, and to find out whether miniplates were sufficiently stable for application at the mandibular angle. PATIENTS: Data from 277 patients with 293 fractures of the mandibular angle have been evaluated. METHODS: A computation model using finite elements was established in order to compute mechanical stress occurring in osteosynthesis plates used for fixation of fractures of the mandibular angle. In the second part of this study, the data from all in-patients treated for fracture of the mandibular angle were evaluated retrospectively. Age and sex of the patients, cause of fracture, state of dentition, type of therapy as well as complications were noted. RESULTS: In those tests, both the 1.0 mm miniplate and the 2.3 mm module plate were sufficiently stable. The rate of major complications (requiring revisional surgery with general anaesthesia) amounted to approximately 17% in comminuted fractures, or in non-compliant patients in which primary stability with a single miniplate did not appear sufficient, so that other osteosynthesis methods were used in addition. This rate was considerably higher than that in simple mandibular fractures. Simple fractures of the mandibular angle were just treated with one miniplate following Champy's guidelines strictly. In these fractures the rate of major complications was only 2.3%. CONCLUSION: In comminuted fractures and in non-compliant patients, the use of a stronger osteosynthesis material should be considered while in all other cases application of a single 1.0 mm miniplate was regarded as sufficient for fixation using open reduction.

Adolescent↗

PubMed2003

Distraction osteogenesis and tissue engineering--new options for enhancing the implant site.

In severe atrophy of the mandible, implant placement in original bone may not be possible. In this field, augmentation procedures have already been described and controversially discussed. By the use of distraction osteogenesis, bone augmentation without donor morbidity is obtained, while the implant-bone interface remains in original bone. Despite soft tissue expansion during the distraction process, a lack of attached gingiva may cause difficulties at the implant site. In certain cases, an additional soft tissue augmentation procedure has to be performed for a good long-term functional and esthetic rehabilitation. The connective tissue graft and the free gingival graft are recommended to be standard procedures to create a stable periimplant mucosa, but the morbidity and the size limitation of the donor site have to be taken into consideration in selected patients. Transplantation of in vitro-cultured keratinocytes could be an alternative. Distraction osteogenesis and tissue engineering of keratinocytes, as well as bone-cultivating techniques, may increasingly be valuable adjuncts to current augmentation procedures.

Adult↗

PubMedDate not supplied

Influence of harvesting technique and donor site location on in vitro growth of osteoblastlike cells from facial bone.

PURPOSE: Donor morbidity is minimized when tissue engineering is applied to produce osteogenic grafts by growing osteoblasts on biomaterials. However, limiting factors are the origin, proliferation, and differentiation of osteoblasts. Therefore, the aim of this study was to evaluate the efficacy of growing osteoblasts from different types of bone samples and to assess the influence of the donor site. MATERIALS AND METHODS: From 28 patients 37 bone specimens were obtained during removal of third molars in the maxilla and mandible. Seventeen specimens were bone chips and 20 were bone sludge. After subculturing primary cultures, histochemical and immunhistochemical tests (EZ4U test, BrdU labeling, ALP histochemistry, type I collagen immunohistochemistry, osteocalcin ELISA) were performed to determine cell proliferation, viability, and differentiation. RESULTS: Both bone chips and bone sludge from the mandible and maxilla are suitable for culturing human osteoblastlike cells. However, bone chips were superior to bone sludge with respect to ability to grow cells, and maxillary bone was superior to mandibular bone in this regard. Harvesting technique had only little influence on the expression of cell differentiation markers (ALP, type I collagen, osteocalcin). DISCUSSION AND CONCLUSION: Chips from human membrane bone, especially from the maxilla, are suitable for culturing high numbers of differentiated osteoblastlike cells. These cells may be used to tissue engineer bone grafts, which may be used to enhance the implant placement site.

Adolescent↗