New technology for the removal of corundum residues on dental implants.

Surface modification is an important measure to improve dental implants. Corundum residues, which are part of current dental implant blasting, on Straumann dental implants, were found to have disappeared in recent publications. We further evaluated this new cleaning technology by evaluating the surface of four different Straumann implants using scanning electron microscopy (SEM) and energy-dispersive radiographic spectroscopy (EDX). The involved technology fits to a Straumann patent involving a dextran coating allowing easy corundum particle removal by aqueous solution.

Local and systemic risk factors influencing the long-term success of angular stable alloplastic reconstruction plates of the mandible.

INTRODUCTION: After ablative surgery of the mandible, angular stable alloplastic reconstruction plates are commonly employed. The aim of the study was a long-term evaluation of local anatomical, as looking at systemic factors influencing specific complications and the failure rate of such plates. MATERIALS AND METHODS: In a retrospective study covering an 11-year period, we reviewed the outcomes of angular stable plates of patients who had a segmental resection of the mandible and subsequent alloplastic reconstruction. Complications and failure rates were assessed and local (anatomical size and localization of resection) as well as systemic risk factors (age, sex, radiation therapy, smoking) evaluated. RESULTS: Altogether, 162 plates were reviewed. The overall complication rate was 28% (fractures n = 8, loose screws n = 7, dehiscences n = 31) after an average time of 13 months. Cumulative survival rates of 73% after one, of 67% after 2, of 59% after 3 and of 40% after five years were observed. We found a significant correlation of increasing defect sizes to a rising complication and failure rate. Plate dehiscence occurred more often in defects including the midline (p = 0.005). Though not statistically significant, the occurrence of plate fracture was associated with lateral mandibular defects (7/8, p = 0.113). In smoking patients an earlier failure rate was seen. CONCLUSION: The results clearly indicate that the success of alloplastic reconstruction plates of the mandible is dependent on various risk factors. They should--if possible--be used temporarily only. If not done primarily, a secondary approach with bone reconstruction is recommended.

Multiple primary enoral soft tissue manifestations of a Hodgkin lymphoma--case report and literature review.

BACKGROUND: Hodgkin lymphoma (HL) are lymphoproliferative neoplasms, histologically comprising of mononuclear and multinucleated Hodgkin and Reed Sternberg cells (HRS). About 4 % of all lymphatic malignancies of the head and neck are HL. The typical disease presents itself as a nodal lesion. Extranodal, enoral soft tissue involvement by HL is very rare. CASE REPORT: A 73-year-old man with a suspect, ulcerating lesion in the left retromolar region of the mandible was assigned to our hospital. Prior anti-inflammatory therapy has been without success. Subsequently, three biopsies were taken which could only show inflammation. Finally, two biopsies from the left retromolar region and the left inner cheek showed HRS cells with positive expressions of CD15 and CD30 corresponding to a Hodgkin lymphoma. No lymphatic node or bone involvement could be detected. The patient was designated to receive radio-chemotherapy, but died 3 weeks after diagnosis of multiple organ failure. In a literature review, together with this report, nine cases were found concerning primary HL of the oral mucosa. Accordingly, this is the first case of primary multiple extranodal HL in the oral mucosa in absence of lymphatic node involvement. DISCUSSION: Neither clinical features nor radiological appearances of HL presenting as primary enoral lesions are pathognomonic. Especially when only small biopsy specimens are available, histological diagnosis remains challenging, may lead to a delay in therapy and may result in a significant worse prognosis.

Dexrazoxane shows cytoprotective effects in zoledronic acid-treated human cells in vitro and in the rabbit tibia model in vivo.

INTRODUCTION: Bisphosphonates are important and effective drugs in oncology and osteoporosis therapy. They accumulate in the bone matrix becoming released and active by bone resorption. This leads to effective inhibition of tumor cells and bone degradation. A side effect of bisphosphonates similar to other drugs like denosumab is osteonecrosis of the jaws (ONJ). This problem mostly occurs after tooth extraction. We studied the cytoprotectant dexrazoxane known from anthracycline chemotherapy for cytoprotection in nitrogen-containing bisphosphonate treated cells and in the rabbit tibia model to evaluate a possible value in ONJ management. MATERIALS & METHODS: Human osteoblasts (HOB) P2 cells and Human ginigiva fibroblasts (HGF) P2 cells were treated with zoledronic acid (50 µmol/L) and the cytoprotectant dexrazoxane (600 µmol/L). Analysis included cell viability testing with MTT assay and morphology analysis using CellTracker™ Green CMFDA. A biomaterial carrier (Bio-Oss Collagen) was implanted in the rabbit tibia of 6 female chinchilla bastard rabbits on both sides with drill hole defects (d: 3.2mm). Implants were loaded with 25 nmol zoledronic acid, with and without 300 nmol dexrazoxane and unloaded in a control group. Analysis included histological examination of undecalcified samples with toloudine blue staining after 10 days. RESULTS: In vitro experiments showed a significantly higher MTT activity in cells treated with zoledronic acid together with dexrazoxane compared to the same cells treated with the bisphosphonate alone in t-test (HOB: p=0.0003; HGF: p below 0.0001) and one-way ANOVA. Cell morphology changes were consistent with these results. In vivo results showed newly formed bone trabeculae directly growing towards the implanted hydroxylapatite particles and cortical bone interface resorption activities in the control and the experimental group only. CONCLUSION: The study suggests a possible value of this patented technology for ONJ therapy and prevention with local or systemic application.

Dose-dependent osteoinductive effects of bFGF in rabbits.

Growth factors lead to the induction of tissue regeneration in bone healing when coated on biomaterials. Basic fibroblast growth factor (bFGF) combines osteoinduction and neoangiogenesis. This study evaluated bFGF-coated hydroxylapatite implants in two experimental groups with 10 or 100 microg (n = 5 per group) compared with uncoated control implants in the rabbit patellar groove model. We observed an unexpected ineffectiveness compared to the control groups with no significant difference of bone growth after 35 days. However, all samples from the 100 microg experiment (control and coated implant) showed significantly stronger 19-25 day label than both 10 microg groups (control and coated implant). Earlier bone labels are stronger in the 10 microg group with equal observation of similarity between experiment and control site and may indicate a possible inhibitory effect of the higher dosing or osteoclast induction. This result indicates a possible systemic effect of the transient growth factor coating.

High-density polyethylene facial implants show surface oxidation in SEM and EDX examination: a pilot study.

Previous histopathological studies on explanted Medpor high-density polyethylene (HDPE) facial implants indicated signs of material destruction and claimed to observe phagocytized HDPE particles within the tissue samples beside the usual type IV reaction with severe fibrosis. We examined new and explanted Medpor material with scanning electron microscopy (SEM) and energy-dispersive X-ray analysis (EDX). The implant surface of three patient-derived specimens showed significantly higher oxygenation in EDX analysis and morphological changes in SEM compared to the new unused material directly after opening of the package and after 1 year of exposure to air. Our preliminary findings indicate a possible oxidative biocorrosion in HDPE surgical implants. Further studies should confirm these pilot project results.

A new technique for the transcrestal sinus floor elevation and alveolar ridge augmentation with press-fit bone cylinders: a technical note.

BACKGROUND: The minimally invasive sinus floor elevation as first described by Summers is limited in the volume of augmentation that is possible. In contrast, the more invasive approach is the sinuslift of Tatum which is indicated for greater bone deficiencies. Therefore, a new technique was developed for transcrestal elevation of the sinus floor and alveolar ridge augmentation with bone dowels in press-fit technique. MATERIALS & METHODS: The crestal cortical bone is cut with a hollow grinder followed by an indirect sinus floor elevation with a plunger. The cylindrical defect is then filled with a cylindrical bone transplant with the press-fit technique. RESULTS: The method was tested in ten fresh porcine skulls and was successful when applied subsequently in two fresh human cadavers (both female, age 60 and 92 years). This was followed by the insertion of another cylinder in overlapping mosaic manner with the dowel-lift technique in the left maxilla in one cadaver. A sinoscopy of the second cadaver experiment showed no perforation of the maxillary sinus membrane. The result was convincing. CONCLUSION: A new method for transcrestal elevation of the maxillary sinus floor and alveolar ridge augmentation with bone cylinders in press-fit technique was developed. The operation combines the minimally invasive approach of Summers with a large augmentation volume otherwise requiring the direct technique of Tatum. These results should encourage further preclinical experiments.

The mechanically stable steam sterilization of bone grafts.

Bone allografts are the standard material used in augmentative bone surgery. However, steam-sterilized bone has a low mechanical stability and limited ossification based on low strain-adapted bone remodelling. Here we describe a new technique which allows the bone to be autoclaved without losing its mechanical stability and osteoconductivity. The compression strength of the new material was compared with steam-sterilized and fresh bone based on mechanical testing using bone cylinders (n=30/group). Allogeneic new material and fresh bone were press-fit implanted into rabbit patellar grooves and examined under fluorescent light and conventional microscopy. Initial healing was assessed after 30 d (n=5/group). Osseous integration and remodelling was studied after 100 d (n=12/group). Steam-sterilized bone showed no mechanical stability, whereas the new material was stiff and had compression curves similar to fresh bone; both groups showed equal degrees of direct ossification after 30 d, advanced bony ingrowth and remodelling after 100 d, and similar ingrowth depths on histomorphometric analysis. The new method preserved the stiffness and osteoconductivity of bone after steam sterilization, and microstructure, mineralization, and composition were conserved. This technique could be useful for bone banking in Third World countries.

[A new technique for transcrestal sinus floor elevation with press-fit bone cylinders (dowel lift): short communication of the first in vitro results]. / Eine neue Technik zur indirekten Sinusbodenelevation mit Knochendübeln in Press-fit-Technik (Dowel-Lift): Kurze Vorstellung der ersten In-vitro-Ergebnisse.

The minimally invasive sinus floor elevation as first described by Summers is limited in augmentation volume, whereas a more invasive approach is required for the technique of Tatum for larger bone defects. We developed a new technique for the transcrestal elevation of the sinus floor with bone dowels using a press-fit technique (dowel lift). We present the technique with first in vitro results in a fresh, unpreserved, human cadaver.

[Craniofacial augmentation with porous polyethylene implants (Medpor: first clinical results]. / Gesichtsschädelaugmentationen mit porösen Polyethylenimplantaten (Medpor): Erste klinische Ergebnisse.

SUBJECT: Porous polyethylene (Medpor) is an alloplastic material commonly used in craniofacial reconstruction. We report about our first clinical experiences with Medpor for facial augmentation procedures. PATIENTS AND METHODS: We treated 27 patients between 2001 and 2005 (11 female, 16 male) with 48 Medpor-implants. The indications for application of porous polyethylene implants in our clinic were congenital malformations (15), post-traumatic defects (10), and reconstructions after tumor resection (2). The implants were used for nasal/paranasal augmentations (16), for zygomatico-orbital augmentations (18), and for augmentations of the chin and malar region (11). The procedures were performed in a standardized manner. We used prefabricated, self-contoured implants and fixed them subperiosteally with titanium osteosynthesis screws. All operations were performed under general anesthesia. We evaluated the aesthetic results and the ingrowth behavior clinically and histologically. RESULTS: We achieved good aesthetic results and the patients showed no signs of discomfort or rejection. Four patients required a second intervention. These revision surgeries included two cases of local infections and two for aesthetic contouring. The necessary reduction of the implants allowed the harvesting of tissue and implant samples for microscopy. CONCLUSION: Porous polyethylene implants showed a good fibrovascular integration without encapsulation under the light microscope. Giant cells were detected on the surface of the implants. Besides this there was evidence for resorption of the implant material. Fixation with titanium screws is very effective. No implant dislocation or implant fracture occurred. The implants showed high volume stability and were easily handled and contoured. It is not possible to visualize Medpor implants with current imaging techniques, because polyethylene shows no contrast.

Liposome mediated gene transfer into the rat oesophagus.

BACKGROUND: Cancer of the oesophagus has so far eluded every attempt at pharmacological treatment. The recent advent of somatic gene therapy offers a new therapeutic approach to malignant tumours. AIM: To investigate whether and how gene transfer into the oesophagus can be achieved. METHODS: A LacZ reporter gene was used as marker and transferred into the oesophagus of rats using cationic liposomes. Gene transfer was achieved by either luminal instillation into a closed segment using a double balloon catheter, or by intramural injection through a needle. Expression of beta-galactosidase was monitored in the oesophagus and various control tissues by histochemistry, polymerase chain reaction (PCR), reverse transcriptase PCR, and Southern blotting. RESULTS: Up to 100 days after in vivo gene transfer beta-galactosidase activity could be demonstrated in the oesophagus. Following luminal application, the transgene was expressed in epithelial cells whereas intramural injection induced preferential expression in fibroblasts. CONCLUSION: In vivo gene transfer into the esophagus is feasible and safe, and the route of administration largely determines cell type specificity. This novel approach will enable in vivo studies of growth, differentiation, and malignant transformation in the oesophagus, and may open new avenues to the confinement of oesophageal malignancies.

Liposome mediated in vivo gene transfer into different tissues of the gastrointestinal tract.

The possibility to transfer and express genetic material in mammalian cells represents a new approach to the treatment of genetic and acquired disorders. So far, most studies use in vitro techniques to introduce foreign DNA into cultured cells, followed by reintroduction of these genetically altered cells into living organisms. In the present study we demonstrate that the LacZ marker gene can be selectively delivered, by in vivo techniques, to various locations of the gastrointestinal tract. Genetic material was targeted to the stomach, the colon, the liver and the pancreas using cationic liposomes. For transfer into the stomach and colon an intraluminal application, in the liver a portal access and in the pancreas an intraductal infusion was chosen. 48 hours after administration, the LacZ gene product beta-galactosidase could be localized in these tissues by cytochemistry. These experiments suggest a new approach to study gastrointestinal physiology and may offer novel aspects for the treatment of gastrointestinal diseases.