Witold Bojar

DDS, PhD
Professor (Assistant)

Publications

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    ABSTRACT: Over the last few years, alloplastic bone substitute materials are raising much interest as an alternative to autologic transplants and xenogenic materials especially in oral surgery. These non-immunogenic and completely resorbable biomaterials are becoming the basis for complete and predictable guided bone regeneration in many cases. The objective of our research was to evaluate the dynamics of bone formation in rats' skulls after implantation of the new chitosan/tricalcium phosphate/alginate biomaterial in comparison to the commercially available alloplastic bone graft. A total of 45 adult male rats weighing 300-400 g were used for the study. The 85-mm-diameter defects in calvaria bone were prepared with a trephine bur, and then filled with the bone substitute materials: chitosan/tricalcium phosphate/alginate or easy-graft Classic (Degradable Solutions AG) (EA) or left just with the blood clot. Animals were sacrificed at 1 and 3 months for histological, histomorphometrical and micro-tomographic evaluations. Histological evaluation at 1 month showed early new bone formation, observed around the experimental biomaterial (CH/TCP/Alg). There were no features of purulent inflammation and necrosis or granulomatous inflammation. Microscopic examination after 3 months following the surgery revealed trabecular bone formation around chitosan-based bone graft with no significant inflammatory response. Less satisfactory and differing results were observed for the commercially available EA and control blood clot. The tested material (chitosan) showed a high degree of biocompatibility and osteoconductivity in comparison with the control groups. Additionally, it seemed to be a "user-friendly" material for oral surgeons.
    Journal of Biomaterials Applications 06/2013; · 2.64 Impact Factor
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    ABSTRACT: Alloplastic bone substitute materials are raising some more interest as an alternative for autologic transplants and xenogenic materials especially in oral surgery over the last few years. These non-immunogenic and completely resorbable biomaterials are the basis for complete and predictable guided bone regeneration. In the majority of cases, such a material is chosen because of its convenient application by surgeons. The main objective of our project was to design and fabricate an osteoconductive, injectable and readily tolerable by human tissues biomaterial for guided bone regeneration. For this purpose, a self-setting composite consisting of chitosan/tricalcium phosphate microparticles and sodium alginate was made. The material obtained was characterized by microsphere and agglomerate morphology and microstructure. Its features relating to setting time and mechanical properties were precisely investigated. Our material was also evaluated according to PN-EN ISO 10993 Biological evaluation of medical devices, i.e., the in vitro tests for genotoxicity and cytotoxicity were conduced. Then, the following examinations were performed: subchronic systemic toxicity, skin sensitization, irritation and delayed-type hypersensitivity and local effects after implantation. The material tested showed a high degree of cytocompatibility, fulfilled the requirements of International Standards and seemed to be a "user friendly" material for oral surgeons.
    Acta of bioengineering and biomechanics / Wroclaw University of Technology 01/2012; 14(1):39-44. · 0.33 Impact Factor
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    Witold Bojar, Witold Walke
    Solid State Phenomena 01/2012; 183:17-24.
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    ABSTRACT: The main objective of the work was to design and fabricate an injectable biomaterial with osteoconductive properties for bone augmentation and potential to be used in dental applications in peri-implant therapy concerning guided bone regeneration. For this purpose, a self-setting biomaterial consisting of chitosan/ tricalcium phosphate microparticles and sodium alginate was formulated (CH/TCP/Alg). The obtained material was characterized as far as microsphere and formed agglomerates morphology and microstructure. Physical properties relating to setting time and mechanical properties were also investigated. Finally, in vivo response to implanted biomaterial was studied on rat model and compared with commercially available alloplastic material. The obtained results showed that designed injectable biomaterial fulfilled main requirements for guided bone regeneration application
    Inżynieria Biomateriałów. 10/2011; XIV(105):20-24.
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    ABSTRACT: Background. Biocompatibility can be described as the ability of a material to function so as not to violate cell and tissue integrity when applied. Objectives. The contemporary requirements for biocompatible materials evaluated according to “evidence−based medicine” induced the authors to evaluate the mutagenicity and cytotoxicity of dental materials (medical devices) authorized for sale in the EU. The use of some endodontic materials is questioned by many specialists. Material and Methods. The Ames test was used to evaluate the mutagenicity of the most controversial endodontic cement, N2, according to the PN−EN ISO 10993−3:2008 norm. The cytotoxicity of this material was evaluated according to the PN−EN ISO 10993−5:2008 norm. Results: The tested material did not show any mutagenic activity, but it was severely cytotoxic in the concentration range of 0.78–200 mg/ml. Conclusions. In view of the broad availability of safe and effective alternatives, the use of paraformaldehyde−containing “aged” filling materials or root canal sealers is undoubtedly below the standard of care for endodontic treatment
    Advances in Clinical and Experimental Medicine 11/2009; 18(6):615-621. · 0.09 Impact Factor
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    ABSTRACT: Background. The objective was to identify the microorganisms present on polyglycolic−acid braided suture material coated with triclosan used in the oral cavity and the in vitro evaluation of the bactericidal properties of triclosan−coated material. Material and Methods. Material was collected from 11 patients subjected oral surgery. The first material was nonabsorbable monofilamen the second triclosan−coated multifilament. Both threads were sutured simultaneously to the same wound. The suture materials were excised 7 days after surgery and placed onto transport medium plates. Identification was carried out with commercial API tests. Most of the isolated strains were classified as Streptococcus. In vitro tests were performed in two stages. The first test was carried out with the coated materials placed directly onto plates inoculated with microbes isolated from the patients. In the second test the sutures were first rinsed for 24 h in isotonic salt solution. Zones of growth inhibition were evaluated after 48 h. Results. There was no significant difference in colony count and species of microbes isolated from triclosan−coated and uncoated material. The growth inhibition of Streptococci did not exceed 2 mm and was observed only with unrinsed triclosan−coated material. A larger zone of inhibition of up to 20 mm was noted only with the control strain E. coli ATCC 25922 with both unrinsed and rinsed material. Conclusions. In the absence of demonstrated differences in colonization between sutures coated with triclosan and regular multifilament suture and their bactericidal properties, the choice for suture material should be its convenience for the surgeon rather than its ability for bacterial adherence
    Advances in Clinical and Experimental Medicine 06/2009; 18(4):401-405. · 0.09 Impact Factor
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    ABSTRACT: The idea of using ozone to disinfect root canals is of recent origin. The wide acceptance of epoxy resin-based sealers lead us to investigate whether ozone can influence the adhesion to the dentin. In this study, we tested the shear bond strength of AH Plus and EZ Fill. Forty freshly extracted bovine teeth were randomly divided into 5 groups. 16 of these samples were treated with ozone for 60 seconds (HealOzone, Kavo). 8 samples were conditioned with the G Bond bonding system. The groups tested were: (1) AH Plus, (2) AH Plus and ozone, (3) EZ Fill, (4) EZ Fill and ozone, (5) AH Plus and G Bond. 48 hours after being prepared the specimens were tested for shear bond strength. Statistical analysis showed significant differences between materials (AH Plus > EZ Fill) and significant, positive influence of ozone and bonding agent on the shear bond strength.
    Acta of bioengineering and biomechanics / Wroclaw University of Technology 01/2009; 11(3):41-5. · 0.33 Impact Factor
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    ABSTRACT: Streszczenie Wstęp: czy jest jeszcze miejsce dla formaldehydu we współczesnej praktyce stomatologicznej? Niektórzy lekarze wciąż rutynowo używają past dewitalizują-cych zawierających paraformaldehyd. Z kolei na rynku są dostępne materiały do wypełniania kana-łów korzeniowych uwalniające ten związek. Cel pracy: oceniono cztery materiały endodontycz-ne pod względem ilości uwalnianego formaldehydu. Materiał i metody: do badań wybrano AH Plus, En-domethasone N, EZ-Fill oraz cement N2. Badania wykonano za pomocą wysokosprawnej chromato-grafii cieczowej (HPLC) po derywatyzacji 2,4-dini-trofenylohydrazyną. Wyniki: najwięcej formaldehydu uwolniło się z ce-mentu N2 (2,91mg; 2,91%), znacząco mniej z EZ--Fill (1864ppm; 0,186%), zaś z materiałów Endo-methasone N i AH Plus uwalniały się śladowe jego ilości (około 2ppm; 0,0002%). Podsumowanie: na rynku wciąż są dostępne mate-riały do wypełniania kanałów korzeniowych uwal-niające znaczną ilość formaldehydu. Z naszych ba-dań wynika jednak, że uwalnianie formaldehydu nie może być jedynym elementem oceny bezpieczeństwa materiałów endodontycznych. Summary Introduction. Is formaldehyde still useful in modern dental practice? Some practitioners still routinely use devitalizing pastes containing paraformaldehyde. Also there are some root canal sealers on the market which release this compound. Aim of the study: To examine four root canal filling materials for the amount of released formaldehyde. Materials and methods: The chosen materials included: AH Plus, Endomethasone N, EZ-Fill and N2 cement. Tests were performed with High Performance Liquid Chromatography method with 2,4-dinitrofenylohydrazin derivatization. Results: N2 cement released the highest amount of formaldehyde (2.91 mg; 2.91%). Significantly less formaldehyde was released from EZ-Fill (1864ppm; 0.186%). The amounts released from Endomethasone N and AH Plus were negligible (ca. 2ppm; 0.0002%). Conclusion: Endodontic materials releasing significant amounts of formaldehyde are still available on the market. However, according to this study, formaldehyde release cannot be the only criterion of the safety of endodontic materials.
    Czasopismo stomatologiczne 01/2009;
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    ABSTRACT: Introduction: According to the assumptions of “evidence-based dentistry” materials used in endodontics should be biocompatible and should not provoke any mutagenicity. Aim of the study: To evaluate mutagenic action of root canal sealers and gutta percha. Material and methods: Five root canal sealers have been examined: AH Plus, Apexit, Canason, Endomethason N and Endorez as well as gutta question was assessed with Ames test. The test itself was performed in accordance with PN-EN ISO 10993-3 and OECD 471 norms. Results: All the examined sealers did not manifest any mutagenic properties.
    Czasopismo stomatologiczne 01/2007; 60(10):656-662.
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    ABSTRACT: According to some researchers, antimicrobial activity is a desirable feature of an endodontic sealer. The antimicrobial effect can be helpful in destroying any microbes remaining in the root canal after chemo-mechanical treatment. A modified agar diffusion method was used to evaluate the antibacterial activity of eight root canal sealers: AH Plus, Apexit, Canason, Diaket, Endion, Endomethasone, Ketac Endo and Sealapex. Tests were performed 1h, 24h and 7 days after preparation of speciments. The materials evaluated showed a varied influence on the growth of bacterial and fungal strains (Streptococcus sanguis, Streptococcus mitis, Enterococcus faecalis, Peptostreptococcus anaerobius, Aspergilus niger). Canason, Diaket and, to a lesser extent, Endomethasone possessed antimicrobial activity against the microbes used in this study.
    Czasopismo stomatologiczne 01/2002; 55(11):695-699.
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    Nowa Stomatologia. 01/2001;
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    Nowa Stomatologia. 01/2001;
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    Nowa Stomatologia. 01/2000;
  • Acta of bioengineering and biomechanics / Wroclaw University of Technology 01/1999; · 0.33 Impact Factor

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