Andre Büchter

Publications of Andre Büchter

• Development of a validated process for manual preparation of dental transmission instruments.

  Authors: Andre Büchter, Birgit Kruse-Loesler

  Clinical oral investigations. 05/2010;

  The goal of the study was to develop a validated manual preparation process that conforms to the requirements of validation guidelines. Twelve dental transmission devices from various manufacturersThe goal of the study was to develop a validated manual preparation process that conforms to the requirements of validation guidelines. Twelve dental transmission devices from various manufacturers (turbines, handpieces, and contra-angle handpieces) were artificially contaminated with bovine hemoglobin for the test. Ten microliters (corresponding to 800 mug) of bovine hemoglobin solution (concentration 80 mg/ml) was pipetted into the spray water and spray air channels. The manual preparation was conducted by blowing air through the spray channels of the transmission instruments through an attachment to a treatment unit (model 1060T, KaVo, Biberach, Germany) for 5 s. The spray channels were cleaned with WL-Clean (Alpro, Georgen, Germany) as directed by the manufacturer. The spray channels were disinfected with WL-Cid (Alpro) and the spray channels were blow-dried with WL-Dry (Alpro) at the end of the exposure time as directed by the manufacturer. To determine the protein content (protein residue analysis) in the channels of the transmission instruments, 2 ml of an alkaline SDS solution (1%; pH 11) was flushed through the channels. For the quantitative protein residue analysis, the Biuret method was used as described in DIN EN 15883-1:2006. After the application of this method, all results of the protein residue analysis were within the acceptance criteria of the validation guideline. The newly developed manual preparation process is therefore confirmed as suitable from a hygienic viewpoint for preparation of transmission instruments in the dental practice.

• Malignant fibrous histiocytoma of the face: report of a case.

  Authors: László Seper, Richárd Schwab, Sirichai Kiattavorncharoen, Andre Büchter, Agnes Bánkfalvi, Ulrich Joos, József Piffkó, Birgit Kruse-Loesler

  Head & face medicine. 02/2007; 3:36.

  BACKGROUND: Soft tissue sarcomas in the head and neck region are rare and often present a difficult differential diagnosis. The aim of our presentation is to point out the complexity of theBACKGROUND: Soft tissue sarcomas in the head and neck region are rare and often present a difficult differential diagnosis. The aim of our presentation is to point out the complexity of the diagnosis, treatment and follow up. CASE PRESENTATION: An eighty-seven year old female patient was referred to our unit with a fast growing brownish lump on the face. Four months beforehand, a benign fibrous histiocytoma (BFH) had been removed from the same location by excision biopsy with wide tumour-free resection margins. Excision biopsy of the recurrent lesion revealed a malignant fibrous histiocytoma (MFH). Radical tumour resection was completed by extended parotidectomy and neck dissection; the skin defect was covered by a regional bi-lobed flap. No adjuvant radio- or chemotherapy was administered. Full functional and cosmetic recovery was achieved; follow-up has been uneventful more than two years postoperatively. DISCUSSION: Malignant transformation of BFH is extremely rare and if so, extended radical surgery may give a fair chance for a favourable outcome even in patients with advanced age.

• Fast element mapping of titanium wear around implants of different surface structures.

  Authors: Ulrich Meyer, Martin Bühner, Andre Büchter, Birgit Kruse-Lösler, Thomas Stamm, Hans-Peter Wiesmann

  Clinical oral implants research. 05/2006; 17(2):206-11.

  The effect of unintended titanium release around oral implants remains a biological concern. The current study was undertaken to evaluate a new detection system of element mapping in biologicalThe effect of unintended titanium release around oral implants remains a biological concern. The current study was undertaken to evaluate a new detection system of element mapping in biological probes. A new scanning electron microscopy-energy dispersive spectroscopy detection method was used to map the features of titanium contamination in peri-implant bone around implants with different surface structures. The amount of titanium wear was highest adjacent to titanium-plasma-sprayed surfaces, followed by sandblastered large grid acid-etched and smooth surfaces. A high sensitivity of titanium detection over large areas of bone tissue was observed. A high spatial resolution of titanium wear particles (20 nm) could be reached and correlated to the ultrastructural morphological features of peri-implant tissue. Cells adjacent to titanium wear revealed no signs of morphological alterations on a nanoscale level at early periods of implant/bone interaction. The new technique may serve as a fast and effective tool to evaluate titanium release effects in biological probes.

• Biological and biomechanical evaluation of interface reaction at conical screw-type implants.

  Authors: Andre Büchter, Ulrich Joos, Hans-Peter Wiesmann, László Seper, Ulrich Meyer

  Head & face medicine. 02/2006; 2(1):5.

  ABSTRACT : BACKGROUND : Initial stability of the implant is, in effect, one of the fundamental criteria for obtaining long-term osseointegration. Achieving implant stability depends on theABSTRACT : BACKGROUND : Initial stability of the implant is, in effect, one of the fundamental criteria for obtaining long-term osseointegration. Achieving implant stability depends on the implant-bone relation, the surgical technique and on the microscopic and macroscopic morphology of the implant used. A newly designed parabolic screw-type dental implant system was tested in vivo for early stages of interface reaction at the implant surface. METHODS : A total of 40 implants were placed into the cranial and caudal part of the tibia in eight male Göttinger minipigs. Resonance frequency measurements (RFM) were made on each implant at the time of fixture placement, 7 days and 28 days thereafter in all animals. Block biopsies were harvested 7 and 28 days (four animals each) following surgery. Biomechanical testing, removable torque tests (RTV), resonance frequency analysis; histological and histomorphometric analysis as well as ultrastructural investigations (scanning electron microscopy (SEM)) were performed. RESULTS : Implant stability in respect to the measured RTV and RFM-levels were found to be high after 7 days of implants osseointegration and remained at this level during the experimented course. Additionally, RFM level demonstrated no alteration towards baseline levels during the osseointegration. No significant increase or decrease in the mean RFM (6029 Hz; 6256 Hz and 5885 Hz after 0-, 7- and 28 days) were observed. The removal torque values show after 7 and 28 days no significant difference. SEM analysis demonstrated a direct bone to implant contact over the whole implant surface. The bone-to-implant contact ratio increased from 35.8 +/- 7.2% to 46.3 +/- 17.7% over time (p = 0,146). CONCLUSION : The results of this study indicate primary stability of implants which osseointegrated with an intimate bone contact over the whole length of the implant.

• Strain driven fast osseointegration of implants.

  Authors: Ulrich Joos, Andre Büchter, Hans-Peter Wiesmann, Ulrich Meyer

  Head & face medicine. 10/2005; 1:6.

  BACKGROUND: Although the bone's capability of dental implant osseointegration has clinically been utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence andBACKGROUND: Although the bone's capability of dental implant osseointegration has clinically been utilised as early as in the Gallo-Roman population, the specific mechanisms for the emergence and maintenance of peri-implant bone under functional load have not been identified. Here we show that under immediate loading of specially designed dental implants with masticatory loads, osseointegration is rapidly achieved. METHODS: We examined the bone reaction around non- and immediately loaded dental implants inserted in the mandible of mature minipigs during the presently assumed time for osseointegration. We used threaded conical titanium implants containing a titanium2+ oxide surface, allowing direct bone contact after insertion. The external geometry was designed according to finite element analysis: the calculation showed that physiological amplitudes of strain (500-3,000 ustrain) generated through mastication were homogenously distributed in peri-implant bone. The strain-energy density (SED) rate under assessment of a 1 Hz loading cycle was 150 Jm-3 s-1, peak dislocations were lower then nm. RESULTS: Bone was in direct contact to the implant surface (bone/implant contact rate 90%) from day one of implant insertion, as quantified by undecalcified histological sections. This effect was substantiated by ultrastructural analysis of intimate osteoblast attachment and mature collagen mineralisation at the titanium surface. We detected no loss in the intimate bone/implant bond during the experimental period of either control or experimental animals, indicating that immediate load had no adverse effect on bone structure in peri-implant bone. CONCLUSION: In terms of clinical relevance, the load related bone reaction at the implant interface may in combination with substrate effects be responsible for an immediate osseointegration state.

• Image-based extracorporeal tissue engineering of individualized bone constructs.

  Authors: Ulrich Meyer, Andre Büchter, Ariane Hohoff, Elke Stoffels, Thomas Szuwart, Christoph Runte, Dieter Dirksen, Hans-Peter Wiesmann

  The International journal of oral & maxillofacial implants. 20(6):882-90.

  PURPOSE: Computer-aided technologies have been recently employed for use in extracorporeal bone tissue engineering strategies. In this pilot animal experimental study, the intention was to testPURPOSE: Computer-aided technologies have been recently employed for use in extracorporeal bone tissue engineering strategies. In this pilot animal experimental study, the intention was to test whether autologous osteoblast-like cells cultured in vitro on individualized scaffolds can be used to support bone regeneration in a clinical environment. MATERIALS AND METHODS: For this purpose, mandibular bone defects were surgically introduced into the mandibles of minipigs and the scaffold of the defect site was modeled by computer-aided design/computer-aided manufacturing technique. Autologous bone cells from porcine calvaria were harvested from minipigs and grown in culture. Cells were seeded on scaffolds generated by rapid prototyping of polylactic acid/polyglycolic acid copolymers. The defects were then reconstructed by implanting the tissue constructs. RESULTS: The intraoperative sites as well as the postoperative computerized tomographic scans demonstrated an accurate fit in the defect sites. The implanted scaffold constructs enriched with osteoblast-like cells were well tolerated and appeared to support bone formation, as revealed by histologic and immunohistochemical analyses. DISCUSSION: These results indicated that in vitro expanded osteoblast-like cells spread on a resorbable individualized scaffold can be capable of promoting the repair of bony defects in vivo. CONCLUSION: These results warrant further attempts to combine computer modeling and tissue engineering for use in bone reconstructive surgery.