K A Schlegel

Publications of K A Schlegel

• Biofunctionalization of the implant surface with different concentrations of a synthetic peptide (P-15).

  Authors: R Lutz, C Prechtl, J Nonhoff, T Weisel, C J Damien, K A Schlegel

  Clinical oral implants research. 03/2012;

  OBJECTIVE: This study aimed at identifying the ideal concentration of a biofunctional surface coating of dental implants with a synthetic peptide (P-15). In a previous study, P-15 was shown toOBJECTIVE: This study aimed at identifying the ideal concentration of a biofunctional surface coating of dental implants with a synthetic peptide (P-15). In a previous study, P-15 was shown to enhance osseointegration parameters. MATERIAL AND METHODS: Implants (modified ANKYLOS(®) A8; FRIADENT Plus(®) surface) with five different concentrations (0-400 μg/ml) of a P-15 coating as well as uncoated controls were inserted in the frontal bone of 45 adult domestic pigs. The histomorphometric and microradiographic findings for the coated implants were compared to those for the uncoated ones after 7, 14, and 30 days. RESULTS: No significant differences were observed comparing the peri-implant bone density between the coated and uncoated implants The bone-to-implant contact, as the primary histological parameter for osseointegration, showed high rates for all surfaces investigated (between 73.3 ± 17.9% for the control and 81.9 ± 15.2% for P15 20 μg/ml after 30 days). CONCLUSIONS: No significant benefit on osseointegration of a biofunctional P-15 coating of dental implants could be displayed in the present study.

• Oral findings associated with primary hyperoxaluria type I.

  Authors: K T Mitsimponas, T Wehrhan, S Falk, F Wehrhan, F W Neukam, K A Schlegel

  Journal of cranio-maxillo-facial surgery : official publication of the European Association for Cranio-Maxillo-Facial Surgery. 03/2012;

  In the present paper we report the oral findings of a patient who was diagnosed with hyperoxaluria. Hyperoxalurias can basically be classified as primary and secondary, with the first being inbornIn the present paper we report the oral findings of a patient who was diagnosed with hyperoxaluria. Hyperoxalurias can basically be classified as primary and secondary, with the first being inborn errors of metabolism and the second a result of excessive oxalate intake. Primary hyperoxalurias form a rare group of metabolic diseases that are inherited in the autosomal recessive fashion. The affected genes code for specific hepatic enzymes that are involved in glyoxylate metabolism and their deficiency results in overproduction of oxalate. Two different types are described: Primary hyperoxaluria type I results from a deficiency of peroxisomal enzyme alanine-glyoxylate aminotransferase and the more rare type II from a deficiency of cytosolic enzyme d-glycerate dehydrogenase. Since oxalate is primarily excreted through the kidneys, abnormally high concentration of oxalate in the urine occurs. This can in turn result in recurrent kidney stones and parenchymal renal damage and end-stage renal disease (ESRD). Inability to further excrete oxalate through the kidneys leads to its deposition in various organs (oxalosis). Several oral findings have been described in patients with oxalosis, most important of whose are bone resorption in the jaws, external root resorption and rapidly progressive dental mobility, as well as dental pain associated with deposition of oxalate in the dentine and the pulp.

• Osseointegration of SLActive implants in diabetic pigs.

  Authors: K A Schlegel, C Prechtl, T Möst, C Seidl, R Lutz, C von Wilmowsky

  Clinical oral implants research. 11/2011;

  OBJECTIVES: Diabetes mellitus is currently classified as a relative contraindication for implant treatment because of microangiopathies with the consequence of impaired bone regeneration and higherOBJECTIVES: Diabetes mellitus is currently classified as a relative contraindication for implant treatment because of microangiopathies with the consequence of impaired bone regeneration and higher rates of implant failure. The study aim was to investigate peri-implant bone formation in a diabetic animal model in comparison to healthy animals and to evaluate the differences between conventional (SLA(®) ) and modified (SLActive(®) ) titanium implant surfaces on osseointegration. MATERIAL AND METHODS: Each six implants were placed in the calvaria of 11 diabetic and 4 healthy domestic pigs. At 30 and 90 days after implant placement, the bone-to-implant contact (BIC) and bone density (BD) were appraised. Additionally, the expression of the bone-matrix proteins collagen type I and osteocalcin was evaluated at both points in time by using immunohistochemical staining methods. RESULTS: Overall, BIC was reduced in the diabetic group at 30 and 90 days. After 90 days, the SLActive(®) implants showed significantly higher BICs compared with the SLA(®) implants in diabetic animals. Peri-implant BD was higher in the SLActive(®) group at 30 and 90 days in healthy and diabetic animals. Collagen type I protein expression was higher using SLA(®) implants in diabetic pigs at 30 days. Values for osteocalcin expression were not consistent. CONCLUSIONS: The results indicate the negative effect of untreated diabetes mellitus on early osseointegration of dental implants. The modified SLA(®) surface (SLActive(®) ) elicited an accelerated osseointegration of dental implants, suggesting that a better prognosis for implant treatment of diabetic patients is possible.

• Biofunctionalization of titanium implants with a biomimetic active peptide (P-15) promotes early osseointegration.

  Authors: R Lutz, S Srour, J Nonhoff, T Weisel, C J Damien, K A Schlegel

  Clinical oral implants research. 07/2010; 21(7):726-34.

  The early stages of peri-implant bone formation play an essential role in the osseointegration and long-term success of dental implants. By incorporating bioactive coatings, this biofunctionalizationThe early stages of peri-implant bone formation play an essential role in the osseointegration and long-term success of dental implants. By incorporating bioactive coatings, this biofunctionalization of implant surfaces may enhance the attachment of the implant to the surrounding bone and stimulate bone regeneration. To demonstrate faster osseointegration, the surfaces of dental implants were grit-blasted and acid-etched. They were then coated with hydroxyapatite (HA) and experimental implants were further coated with a biomimetic active peptide (P-15) in one of two concentrations. These biofunctionalized samples and controls with no peptide were placed in the forehead region of 12 adult pigs. Six animals were evaluated for a period of 14 or 30 days. Histomorphometric analysis demonstrated that the implants with the high concentration of P-15 had significantly higher percentage of bone-to-implant contact (BIC) at 14 (P=0.018) and 30 (P=0.015) days compared with the other groups. Both concentrations of P-15 showed increased peri-implant bone density compared to the control group at 30 days. Biofunctionalization of the implant surface with a biomimetic active peptide leads to significantly increased BIC rates at 14 and 30 days and higher peri-implant bone density at 30 days.

• Skin repair using a porcine collagen I/III membrane--vascularization and epithelization properties

  Authors: F. Wehrhan, E. Nkenke, I. Melnychenko, K. Amann, K. A. Schlegel, C. Goerlach, W. H. Zimmermann, S. Schultze-Mosgau

  Dermatol Surg. 01/2010; 36(6):919-30.

  BACKGROUND: Collagen membranes have been developed to overcome the problem of limited availability of skin grafts. Vascularization and restricted functional epithelization limit the success ofBACKGROUND: Collagen membranes have been developed to overcome the problem of limited availability of skin grafts. Vascularization and restricted functional epithelization limit the success of bioartificial constructs. OBJECTIVE: To compare the vascularization, epithelization, and integration of a porcine collagen I/III membrane with that of split-thickness skin grafts on skin wounds. MATERIALS AND METHODS: In 21 adult pigs, full-thickness skin defects on the rear side of the ear healed by split-thickness skin grafting, by covering with the membrane, or by free granulation. Skin samples on postoperative days 1, 3, 7, 14, 21, and 28 were evaluated histologically (hematoxylin-eosin, Sirius Red) and using immunohistochemistry (cytokeratin 5/6, transforming growth factor beta receptor (TGFbetaR-III) and immunoblot (TGFbeta(1,3), Smad2/3). Epithelial thickness and TGFbetaR-III-positive capillary area were quantitatively assessed. RESULTS: Epithelization and vascularization in the membrane group were not significantly different from in the group treated with a split-thickness skin graft. Free granulation showed significantly slower epithelization and vascularization (p<.05). TGFbeta(1) and Smad2/3 complex expression were high during free granulation. Matrix was distinguishable until day 7. CONCLUSIONS: This membrane serves as a suitable full-thickness dermal substitute, because the membrane is vascularized faster than free granulation tissue and enables early epithelization.

• [Enophthalmos correction in complex orbital floor reconstruction : Computer-assisted, intraoperative, non-contact, optical 3D support.]

  Authors: T V Kühnel, E Vairaktaris, K A Schlegel, F W Neukam, B Kühnel, L M Holbach, E Nkenke

  Der Ophthalmologe : Zeitschrift der Deutschen Ophthalmologischen Gesellschaft. 07/2008; 105(6):578-83.

  In the case of displacement of the globe such as enophthalmos induced by trauma, the patient is affected on both counts: function and aesthetics. To prevent double vision or conspicuous asymmetry,In the case of displacement of the globe such as enophthalmos induced by trauma, the patient is affected on both counts: function and aesthetics. To prevent double vision or conspicuous asymmetry, exact correction of the globe position is required. The aim of this case report is to demonstrate an intraoperative computer-assisted, non-contact, optical 3D procedure for identification of the globe position to aid in placing the eyeball in the position required in complex reconstruction of the orbital floor. A 33-year-old man presented with a sunken eye on the right side in the horizontal and vertical plane 6 months after having undergone surgery elsewhere for a zygomatico-orbital fracture, also including the orbital floor. The patient was affected by double vision and a noticeable defective globe position. In planning the correction of the globe position, a three-dimensional image of the face with opened eyes was made with the optical sensor. Automatic comparison of symmetry revealed enophthalmos of 4 mm on relative en- and exophthalmometry. The decision was made to lift the orbital floor with a split calvarial bone graft. During surgery the position of the globe was also controlled by the three-dimensional optical technique. At the end of surgery there was exophthalmos of 1 mm. Six weeks after surgery the patient was not affected by any double vision. After 3 and 24 months enophthalmos was 1 mm. This case demonstrates how the non-ionizing, non-contact, optical 3D technique can help in planning, intraoperative transformation, and clinical monitoring to identify the correct position of the corneal vertex in complex orbital floor reconstruction.

• Topical use of platelet-rich plasma to influence bone volume in maxillary augmentation: a prospective randomized trial.

  Authors: H Schaaf, P Streckbein, S Lendeckel, K Heidinger, B Görtz, G Bein, R-H Boedeker, K A Schlegel, H-P Howaldt

  Vox sanguinis. 02/2008; 94(1):64-9.

  BACKGROUND AND OBJECTIVES: The atrophic posterior maxilla often requires restoration of the alveolar ridge due to a lack of bone quantity and quality before dental implant placement. The aim of thisBACKGROUND AND OBJECTIVES: The atrophic posterior maxilla often requires restoration of the alveolar ridge due to a lack of bone quantity and quality before dental implant placement. The aim of this study was to verify the hypothesis that platelet-rich plasma (PRP) has an influence on bone density in the maxilla after sinus floor elevation in combination with autologous cancellous bone from the iliac crest. Therefore, a randomized, prospective, controlled trial was set up in two centres. STUDY DESIGN AND METHODS: Fifty-three patients who underwent osteoplastic bone grafting for sinus floor elevation were included. The intervention group was treated with defined concentrations of PRP in addition to transplanted bone. Bone biopsy was performed 4 months after augmentation. Bone volume was then measured using the histomorphometric parameter bone volume. RESULTS: The histomorphometric evaluation of the biopsies did not indicate superiority of any of the treatments in terms of bone volume. CONCLUSION: Topical use of PRP did not improve maxillary bone volume either clinically relevant or statistically significant compared to that in conventionally treated patients. The use of PRP to support bone regeneration cannot be recommended as a standard method for maxillary augmentation.

• [Computer-assisted orbital floor reconstruction : Use of a CAD/CAM implant with intraoperative contact-free 3D endo- and exophthalmometry.]

  Authors: T V Kühnel, E Vairaktaris, C Alexiou, K A Schlegel, F W Neukam, E Nkenke

  HNO. 10/2007;

  Pronounced enophthalmos can restrict patients both functionally and aesthetically. Typical symptoms are double vision on both eyes and obvious asymmetry, both of which were present in the 67-year-oldPronounced enophthalmos can restrict patients both functionally and aesthetically. Typical symptoms are double vision on both eyes and obvious asymmetry, both of which were present in the 67-year-old male patient presented in this paper.The resulting data of computed tomography was used to fabricate a patient specific ceramic implant for reconstruction of the left orbital floor with an enophthalmos of 4mm. During the surgery the implant fitted anatomically correct, but exophthalmos occurred. The implant needed to be regraded and recontoured in the dorsal fraction, so that overcorrection could be reduced. With the assistance of optical 3D en- and exophthalmometry during surgery, the position of the cornea vertex was reproducible measured. At the end of surgery, exophthalmos was 1.5 mm. After 12 months, enophthalmos of only 1mm exists. This case displays the combination of a patient specific fabricated implant for reconstruction of the orbital floor with optical 3D-en-and exophthalmometry to correct enophthalmos with a high degree of accuracy. Therefore these two techniques in combination should be used when complex corrections of enophthalmos are needed.

• The effect on bone regeneration of a liposomal vector to deliver BMP-2 gene to bone grafts in peri-implant bone defects.

  Authors: J Park, R Lutz, E Felszeghy, J Wiltfang, E Nkenke, F W Neukam, K A Schlegel

  Biomaterials. 07/2007; 28(17):2772-82.

  Successful bone-implant osseointegration in large peri-implant bone defects is often difficult, even through autologous bone grafting. Recently, cell-mediated regional gene therapy was introduced toSuccessful bone-implant osseointegration in large peri-implant bone defects is often difficult, even through autologous bone grafting. Recently, cell-mediated regional gene therapy was introduced to deliver potent morphogens or growth factors in regenerative medicine. We applied liposomal vectors carrying bone morphogenetic protein (BMP)-2 cDNA directly into freshly created peri-implant bone defects on pig calvariae, with or without autologous bone graft. The BMP-2 gene was efficiently introduced into immigrating cells and trabecular cells lining the marginal bone surrounding the bony defect. After 1 week, abundant BMP-2 protein was detected throughout the peri-implant bone defect by immunohistochemistry. At 4 weeks, BMP-producing cells were still present in the defect and peri-implant area, which significantly enhanced new bone formation, compared with the control groups. Interestingly within a week of BMP-2 gene delivery with bone grafts, most osteoblastic cells lining the grafted bone chips also produced BMP-2. Particulated bone was immediately reorganized into newly formed trabecular bone. Grafted bone without BMP-2 gene delivery was still scattered and new bone matrix formation was not detected until 4 weeks after bone grafting. In conclusion, direct application of the BMP-2 gene using a liposomal vector enhanced bone regeneration in a bony defect and gene delivery combined with bone graft could induce a rapid osseointegration of the bone-implant interface at earlier stage.

• Evaluation of substitutes for bone: comparison of microradiographic and histological assessments.

  Authors: M Thorwarth, F Wehrhan, S Srour, S Schultze-Mosgau, E Felszeghy, R D Bader, K A Schlegel

  The British journal of oral & maxillofacial surgery. 02/2007; 45(1):41-7.

  We created defects of standard size in the frontal bones of adult pigs and filled them with four different materials. On six occasions (at 1, 2, 4, 8, 12, and 26 weeks), samples were harvested, andWe created defects of standard size in the frontal bones of adult pigs and filled them with four different materials. On six occasions (at 1, 2, 4, 8, 12, and 26 weeks), samples were harvested, and evaluated by computing microradiographic images. We examined the specimens histologically as controls. After insertion of anorganic materials, microradiographic evaluation was easy and precise, and there were no significant differences between them and the histological controls (p=0.2). A quantitative evaluation of chemically sterilised bone by computer was not possible for more than 4 weeks.

• Preclinical animal study and clinical trail of modified extraoral craniofacial implants.

  Authors: L Petrovic, K A Schlegel, J Wiltfang, F W Neukam, S Rupprecht

  Journal of plastic, reconstructive & aesthetic surgery : JPRAS. 01/2007; 60(6):615-21.

  We report on our experience using a new endosseous implant designed to provide sufficient retention to various types of facial prostheses. In a preclinical animal experiment implants (N=12, 4 x 3.5We report on our experience using a new endosseous implant designed to provide sufficient retention to various types of facial prostheses. In a preclinical animal experiment implants (N=12, 4 x 3.5 mm) were placed in the frontal calvarial region of nine adult pigs. The animals were sacrificed at 2, 4 and 8 weeks to evaluate the implant incorporation microradiographically. The clinical outcome and patient satisfaction of implant-retained prostheses were evaluated in a group of 10 patients with facial defects by using clinical assessment and standardized questionnaires for patients and relatives. In the prospective clinical study 33 identical modified implants for extraoral anchorage were placed for the fixation of various prostheses in the midfacial (eye, nose) and ear regions in the course of a clinical trial and observed over a follow-up period of 34 months. The bone-implant contact in the animal experiment reached 31% (+/-2) at 2 weeks, 39% (+/-1) after 4 weeks and 51% (+/-5) at 8 weeks. In the clinical trial, no implants were lost and all implants remained osseointegrated as confirmed clinically and radiographically, providing a stable prosthetic restoration. The analysis of the questionnaire indicates an improvement of the quality of life of patients with respect to aesthetic and psychological well-being. The results demonstrate that extraoral implants not only achieve sufficient osseointegration but also show good clinical handling and easy fixation possibilities for prosthetic anchorage.

• Expression of interleukin 1-beta, transforming growth factor beta-1, and vascular endothelial growth factor in soft tissue over the implant before uncovering.

  Authors: S Schultze-Mosgau, F Wehrhan, M Wichmann, K A Schlegel, S Holst, M Thorwarth

  Oral surgery, oral medicine, oral pathology, oral radiology, and endodontics. 05/2006; 101(5):565-71.

  BACKGROUND: Overexpression of inflammatory cytokines interleukin 1-beta (IL-1beta), transforming growth factor beta-1 (TGF-beta1), and vascular endothelial growth factor (VEGF) may cause healingBACKGROUND: Overexpression of inflammatory cytokines interleukin 1-beta (IL-1beta), transforming growth factor beta-1 (TGF-beta1), and vascular endothelial growth factor (VEGF) may cause healing impairment following implant insertion, jeopardizing success especially in patients previously irradiated. Limited data is available regarding expression pattern of inflammatory cytokines in peri-implant soft tissue caused by the surgical intervention itself. STUDY DESIGN: This study examined 21 patients receiving dental implants. Biopsies of peri-implant tissue were harvested at re-entry 4 months after initial surgery. Eight patients underwent probing of untreated mucosa. Three groups were created (group 1: regular peri-implant mucosa; group 2: patients with irradiated peri-implant mucosa, radiation treatment due to oral squamous cell cancer; group 3: control). Immunohistochemical staining was performed for TGFss1, IL-1ss, and VEGF. RESULTS: Following the placement of dental implants (group 1 vs group 3) a significant increase (P > .05) in TGF-beta1, IL-1beta, and VEGF expression in the peri-implant mucosa was demonstrated. No alteration of this distinct pattern was found for previously irradiated tissue (group 1 vs. group 2). CONCLUSIONS: The study highlights the fundamental involvement of TGF-beta1, IL-1beta, and VEGF during the regeneration of peri-implant soft tissue structures. The use of extended interim solutions may be one clinical implication of these prolonged tissue remodeling processes.

• Effect of betaTCP filled polyetheretherketone on osteoblast cell proliferation in vitro.

  Authors: L Petrovic, D Pohle, H Münstedt, T Rechtenwald, K A Schlegel, S Rupprecht

  Journal of biomedical science. 02/2006; 13(1):41-6.

  Non-resorbable thermoplastic polymers have become more important for reconstructive surgery due to their excellent chemical and physical properties. Polyetheretherketone-beta-tricalcium phosphateNon-resorbable thermoplastic polymers have become more important for reconstructive surgery due to their excellent chemical and physical properties. Polyetheretherketone-beta-tricalcium phosphate (betaTCP-PEEK) composites were developed as alternative materials for load-bearing applications. This study presents the effect of polyetheretherketone (PEEK) specimens incorporated with 5, 10, 20 and 40 wt% beta-tricalcium phosphate (betaTCP) and processed by injection molding on cultivated osteoblast cells. Normal human osteoblast (NHOst) cells were seeded onto polymer discs to evaluate cell viability and proliferation after 24, 72 and 120 h of cultivation by employing the WST-1 assay. Standard tissue culture plastic was used as a control. The osteoblast cells were found to be viable in all PEEK groups, while the cell proliferation was progressively inhibited due to the incorporated beta-tricalcium phosphate. BetaTCP-PEEK showed concentration independent decrease of cell proliferation compared to the unfilled PEEK and the control group. In summary, this study confirms the non-toxic nature of pure PEEK, whereas this could not definitely be verified for betaTCP-PEEK as a composite material in chosen concentrations of beta-tricalcium phosphate in vitro.

• Onlay augmentation versus sinuslift procedure in the treatment of the severely resorbed maxilla: a 5-year comparative longitudinal study.

  Authors: J Wiltfang, S Schultze-Mosgau, E Nkenke, M Thorwarth, F W Neukam, K A Schlegel

  International journal of oral and maxillofacial surgery. 12/2005; 34(8):885-9.

  Augmentation procedures in the severely resorbed maxilla are standard techniques in preprosthetic surgery. Aim of the present study was to compare onlay bone grafting and sinus floor elevation withAugmentation procedures in the severely resorbed maxilla are standard techniques in preprosthetic surgery. Aim of the present study was to compare onlay bone grafting and sinus floor elevation with autogenous bone grafts in edentulous patients in terms of bone resorption of the posterior alveolar crest and implant survival in a 5-year longitudinal study. A total of 100 patients (53 female and 47 male patients) requiring augmentation using autogenous bone due to a severely resorbed maxillae were evaluated. The degree of resorption and bone quality were preoperatively estimated in panoramic radiographs according to Lekholm and Zarb. The overall 5-year success rate of implants placed after augmentation procedures in the posterior maxilla was 93.1%. Following onlay augmentations 215 out of 235 implant insertions were successful, i.e. a success rate of 91.5% was achieved. In the sinuslift group, 330 out 349 implants remained successful, i.e. a success rate of 94.6% was found. The difference between both groups was statistically significant at the end of the evaluation period. Bone resorption, measured as loss of total bone height in panoramic radiographs, was initially more pronounced following onlay augmentations (>20% after 12 months of observation). The degree of resorption decreased in the further course of the study. Lower resorption rates and a higher overall success rate were demonstrated for the sinus lift group.

• Expression of bone matrix proteins during de novo bone formation using a bovine collagen and platelet-rich plasma (prp)--an immunohistochemical analysis.

  Authors: M Thorwarth, S Rupprecht, S Falk, E Felszeghy, J Wiltfang, K A Schlegel

  Biomaterials. 06/2005; 26(15):2575-84.

  This animal study (domestic pig) examined the bone formation after filling defined defects with autogenous bone or a collagen lyophilisat in combination with Platelet-rich-plasma (PRP) by evaluatingThis animal study (domestic pig) examined the bone formation after filling defined defects with autogenous bone or a collagen lyophilisat in combination with Platelet-rich-plasma (PRP) by evaluating bone matrix proteins. Six groups, both materials with and without PRP in two concentrations (+ 1, + 2) were compared to untreated bone by means of immunohistochemistry at 2, 4, 12 and 26 weeks. BMP-2 expression was increased at 2 weeks in the collagen + 1 group and after 4 weeks in the collagen + 1 and + 2 group. Collagen-I expression was increased at 2 weeks in all collagen groups. After 4 weeks raised levels were observed after adding the higher concentrated PRP to bone and the collagen material. Osteocalcin expression was enhanced at 2 weeks in all collagen groups and the autogenous bone + PRP1 group, after 4 weeks in the bone and collagen + 2 groups. At 12 weeks higher values were observed after adding higher concentrated PRP to bone. Osteonectin and especially osteopontin were confirmed to be effective markers of early bone formation in all specimens. The described setting allows to combine established techniques (microradiography, light microscopy) with approaches to explore the underlying biology (immunohistochemistry) on the same specimen.

• De novo bone formation using bovine collagen and platelet-rich plasma.

  Authors: K A Schlegel, K Donath, S Rupprecht, S Falk, R Zimmermann, E Felszeghy, J Wiltfang

  Biomaterials. 11/2004; 25(23):5387-93.

  In order to regenerate critical-size bone defects, a variety of bone substitutes is used in addition to autogenous bone. The regenerative capacity of these bone substitutes is usually compared to theIn order to regenerate critical-size bone defects, a variety of bone substitutes is used in addition to autogenous bone. The regenerative capacity of these bone substitutes is usually compared to the efficacy of autogenous bone known as the "golden standard". Different cytokines influence the regeneration process because of their morphogenic or mitogenic properties. Platelet-rich plasma (PRP), a platelet concentrate, is characterised by having a positive effect on wound healing, reducing bone graft resorption and increasing the density of bone transplants. This experiment was commenced with a view to studying the osseous defect regeneration after placing various combinations of "filler materials" in experimentally created defects in the forehead of adult pigs. Regeneration by means of grafted autogenous bone (Group 1) or a bovine collagen based medical device (Group 4) alone and combined with PRP in two concentrations (Groups 2, 3, 5 and 6) was evaluated by means of microradiography and light microscopy after 2, 4 and 12 weeks. The microradiographic and light microscopic findings showed that autogenous bone in combination with PRP (Groups 2 and 3) had a significant accelerating effect on early bone regeneration (2 weeks). This effect was not evident when PRP was added to the bovine collagen (Groups 5 and 6). When using the collagen alone, significantly higher mineralisation values were achieved after 2 and 4 weeks than when using autogenous bone alone. After a 12-week observation period, the existing differences between the healing processes in the various groups were more or less levelled out. In summary, the results of the study indicate that clinically autogenous bone, as expected, is the ideal defect filler. Combining autogenous bone with PRP did not provide significantly better results. The findings in the groups treated with bovine collagen indicate that its local application mimics the effect of autogenous bone and amplifies bone regeneration when comparing with the control defect.

• [Experimental pilot study on surface activation of implants with liposomal vectors]

  Authors: M Thorwarth, K A Schlegel, J Wiltfang, S Rupprecht, J H Park

  Mund-, Kiefer- und Gesichtschirurgie : MKG. 08/2004; 8(4):250-5.

  BACKGROUND: Surface coating with mitogenic or morphogenic proteins can improve the healing of bone adjacent to implants and increase the bone-implant interface. Clinical surveys have shownBACKGROUND: Surface coating with mitogenic or morphogenic proteins can improve the healing of bone adjacent to implants and increase the bone-implant interface. Clinical surveys have shown liposome-mediated gene transfer to be a promising and safe new therapeutic method. The aim of our study was to evaluate an experimental model of new approaches for topical treatment of the implant surface and of periimplant defects by using DNA liposomes encoding for BMP-2 (bone morphogenetic protein). MATERIAL AND METHODS: A total of 27 implants (3.5 x 14 mm) were placed in critically sized defects of the frontal skull bone of adult pigs (n=3). The bottom of the implant was placed in the base of the defect which guaranteed primary stability, whereas the superior part of the implant (10 mm) represented an implant in a defect area. Liposomes containing DNA encoding for BMP-2 and GFP (green fluorescence protein) were used. In a first trial GFP-DNA liposomes on a collagen matrix were directly applied to the periimplant defect. In a second stage, the surface of the implants was encoded with BMP-2 DNA liposomes. Subsequently, these implants were inserted in the manner described. The resulting bone samples were prepared for immunohistochemical staining. Staining for GFP was performed in the area of the defect and for BMP-2 on the bone-implant interface. RESULTS: Immunohistochemical staining on day 3 postoperatively revealed an increased GFP expression in the periimplant defect. Therefore, the effectiveness of the liposomal vector was verified for the chosen animal model. On the surface of the implants encoded with BMP-2 DNA liposomes an increased BMP-2 expression was found. Thus, the liposomal vector system was validated also for BMP-2 DNA transfer in the chosen animal model. Further, the established system allows a sustainable and delayed release of BMP-2 in the area of the bone-implant interface. CONCLUSIONS: As a result of the study we were able to collect data concerning the influence of implant surface conditioning on the bone-implant interface and on therapeutically relevant options for the treatment of periimplant defects. These approaches are currently being evaluated in a long-term study.

• [Applying an osteoinductive protein complex for regeneration of osseous defects]

  Authors: F R Kloss, K A Schlegel, E Felszeghy, S Falk, J Wiltfang

  Mund-, Kiefer- und Gesichtschirurgie : MKG. 03/2004; 8(1):12-7.

  INTRODUCTION: Growth factors are still not commercially available for routine clinical use. One possibility might be the application of Colloss, which is supposed to have osteoinductive properties.INTRODUCTION: Growth factors are still not commercially available for routine clinical use. One possibility might be the application of Colloss, which is supposed to have osteoinductive properties. Therefore, it was the aim of the following animal experimental study to compare Colloss with autogenous bone and to investigate its osteoproductive potential. MATERIAL AND METHODS: In 24 pigs clinically relevant defects were created in the forehead area. Defects were filled with autogenous bone and Colloss. One defect was left unfilled and served as control. After 2, 4, 12 and 26 weeks, six animals were sacrificed and microradiography, light microscopy and immunohistochemistry were carried out using BMP-2 and osteocalcin as antibodies. RESULTS: After 2 weeks the defects filled with the bovine protein complex showed a mineralization of 52.6% +/-4.03 compared to autogenous bone (38% +/-9.9; p=0.068) and the control defect (30% +/-2.94; p=0.05). After 4 weeks the results became assimilated. Light microscopy revealed especially after 2 weeks an enhanced de novo bone formation in the Colloss-group. This was also evident in an early expression maximum of BMP-2 after 2 weeks. Autogenous bone and the control defect showed a later expression maximum. CONCLUSION: Colloss showed an acceleration of bone regeneration in the early phase. Nevertheless, after 26 weeks the results were comparable with the autogenous bone group.

• [Osseous defect regeneration using autogenous bone alone or combined with Biogran or Algipore with and without added thrombocytes. A microradiologic evaluation]

  Authors: K A Schlegel, F R Kloss, S Schultze-Mosgau, F W Neukam, J Wiltfang

  Mund-, Kiefer- und Gesichtschirurgie : MKG. 04/2003; 7(2):112-8.

  In addition to autogenous bone, a variety of bone substitute materials is used to regenerate bony defects. The aim of the study was to evaluate the reossification of critical size defects in the osIn addition to autogenous bone, a variety of bone substitute materials is used to regenerate bony defects. The aim of the study was to evaluate the reossification of critical size defects in the os frontale of adult pigs ( n=16) with microradiography. The defects were filled randomly with autogenous bone or the bone substitute materials Algipore and Biogran each combined with a defined quantity of autogenous bone. Additionally, platelet-rich plasma (PRP) was added in defined quantities (0.5 ml) in two different concentrations (4-fold and 6.5-fold). At 2, 4, 12, and 26 weeks four animals were sacrificed and the osseous regeneration documented by quantitative evaluation of the microradiographic findings. Microradiographic results in the autogenous bone group showed an earlier PRP concentration-dependent mineralization. Over the whole observation period the peak value of autogenous bone as filler alone could not be reached in both PRP groups. Using Algipore, no accelerated effect of mineralization however could be observed. In our study, Biogran proved to be a defect filler only partially suitable for bony defect healing, no matter whether PRP was added or not.

• [In vitro effect of taurolidine on squamous cell carcinoma in the oral cavity]

  Authors: L Petrovic, K A Schlegel, J Ries, J Park, E Diebel, S Schultze-Mosgau, J Wiltfang

  Mund-, Kiefer- und Gesichtschirurgie : MKG. 04/2003; 7(2):102-7.

  Taurolidine (Taurolin) is a derivative of the amino acid taurine, successfully used in the treatment of peritonitis. In vitro and in vivo studies have shown that taurolidine inhibits cellTaurolidine (Taurolin) is a derivative of the amino acid taurine, successfully used in the treatment of peritonitis. In vitro and in vivo studies have shown that taurolidine inhibits cell proliferation and induces apoptosis in a variety of tumor cell lines. At present there are no published studies on the use of taurolidine in the treatment of squamous cell carcinoma. Our aim was to examine the inhibition of cell proliferation and induction of apoptosis in cell lines SCC 4 and SCC 15 treated with taurolidine in concentrations of 0.01%, 0.1%, and 0.5%. Analogue to the present investigations on adenocarcinoma cell lines, we used toxic antiseptic povidone iodine in the same concentration as for the reference group. Untreated cells were used as a control group. The cells were incubated with taurolidine or povidone iodine once for 2 h at 37 degrees C in 5% CO(2). Cell proliferation was assessed using WST-1 labeling kit after 3, 24, 48, 72, and 96 h. The additional measurement of cell apoptosis was examined using ELISA(PLUS) cell death detection kit and performed after 0, 24, and 48 h. The findings showed a significant inhibition of cell proliferation and induction of apoptosis in taurolidine-treated cells SCC 4 and SCC 15 in contrast to the reference group treated with povidone iodine or the untreated control group.