Patrick H. Warnke

Growth and transplantation of a custom vascularised bone graft in a man

BACKGROUND A major goal of research in bone transplantation is the ability to avoid creation of secondary bone defects. We aimed to repair an extended mandibular discontinuity defect by growth of a custom bone transplant inside the latissimus dorsi muscle of an adult male patient. METHODS Three-dimensional computed tomography (CT) scanning and computer-aided design techniques were used to produce an ideal virtual replacement for the mandibular defect. These data were used to create a titanium mesh cage that was filled with bone mineral blocks and infiltrated with 7 mg recombinant human bone morphogenetic protein 7 and 20 mL of the patients bone marrow. Thus prepared, the transplant was implanted into the latissimus dorsi muscle and 7 weeks later transplanted as a free bone-muscle flap to repair the mandibular defect. FINDINGS In-vivo skeletal scintigraphy showed bone remodelling and mineralisation inside the mandibular transplant both before and after transplantation. CT provided radiological evidence of new bone formation. Postoperatively, the patient had an improved degree of mastication and was satisfied with the aesthetic outcome of the procedure. INTERPRETATION Heterotopic bone induction to form a mandibular replacement inside the latissimus dorsi muscle in a human being is possible. This technique allows for a lower operative burden compared with conventional techniques by avoiding creation of a secondary bone defect. It also provides a good three-dimensional outcome.

Bis-phossy jaws - high and low risk factors for bisphosphonate-induced osteonecrosis of the jaw.

INTRODUCTION Bisphosphonates (BPs) have transformed our ability to treat certain malignancies, osteoporosis and hypercalcaemia. This class of drug is assumed to be well tolerated by most. There are some important caveats to this assumption, however, one of the significances being the risk of osteonecrosis of the jaw (ONJ). MATERIAL AND METHODS This multi-centre retrospective study examined the role of different BPs on the development of ONJ, its clinical presentation and the efficacy of various treatment modalities, comparing these findings with the available literature. RESULTS A total of 78 patients from 17 centres were identified with ONJ. A majority of patients identified with ONJ had used Pamidronate or Zoledronate (93.6%) intravenously. 94.9% of patients had received BP in the course of treatment for malignancies and a majority had also received prior chemotherapy or exogenous steroids. 82.1% of patients had received BP for more than 1 year. The mean time from the introduction of BP to the development of ONJ in 24 patients from our department was 31.8 months. CONCLUSIONS The most common intraoral manifestation was exposed necrotic jawbone. Tooth extractions and oral surgical intervention appear to place patients on BP therapy at risk of ONJ, especially after intravenous BP treatments. ONJ proved in this study to be remarkably refractory to treatment, with radical resection being the only curative approach. We recommend that all patients receive necessary dental treatment prior to commencing BP therapy.

Mandibular reconstruction with prefabricated vascularized bone grafts using recombinant human osteogenic protein-1: an experimental study in miniature pigs. Part II: Transplantation

Osteogenic Protein-1 (rhOP-1), also called bone morphogenetic protein-7 (BMP-7), is osteoinductive. The aim of this study was to present a new surgical technique: the prefabrication of a vascularized bone graft using rhOP-1 and its microsurgical transplantation. During 6 weeks, osteomuscular grafts were prefabricated in the latissimus dorsi muscle of five adult minipigs. Six hundred micrograms rhOP-1 on a carrier of xenogenic bone mineral in block form were used. The grafts were transplanted into defects of the mandibular angles performing a microsurgical anastomosis and using miniplates for fixation. Identical defects of the contralateral side were treated by direct application of 600 microg rhOP-1 and xenogenic bone mineral. A polychrome sequential labelling was applied. After transplantation the bone stayed viable, demonstrated by continuous apposition of fluorochromes (non-decalcified histologic sections) and bone scintigraphy. The reconstructive result was significantly superior in the prefabrication technique, assessed by histology and computerized tomography (CT). In conclusion, the method has a potential to become a clinical alternative for conventional vascularized bone grafts.

Osteoporosis and bisphosphonates-related osteonecrosis of the jaw: Not just a sporadic coincidence – a multi-centre study

INTRODUCTION Bisphosphonates (BPs) are powerful drugs that inhibit bone metabolism. Adverse side effects are rare but potentially severe such as bisphosphonate-related osteonecrosis of the jaw (BRONJ). To date, research has primarily focused on the development and progression of BRONJ in cancer patients with bone metastasis, who have received high dosages of BPs intravenously. However, a potential dilemma may arise from a far larger cohort, namely the millions of osteoporosis patients on long-term oral BP therapy. PATIENTS AND METHODS This current study assessed 470 cases of BRONJ diagnosed between 2004 and 2008 at eleven different European clinical centres and has resulted in the identification of a considerable cohort of osteoporosis patients suffering from BRONJ. Each patient was clinically examined and a detailed medical history was raised. RESULTS In total, 37/470 cases (7.8%) were associated with oral BP therapy due to osteoporosis. The majority (57%) of affected individuals did not have any risk factors for BRONJ as defined by the American Association of Oral and Maxillofacial Surgery. The average duration of BP intake of patients without risk factors was longer and the respective patients were older compared to patients with risk factors, but no statistical significant difference was found. In 78% of patients the duration of oral BP therapy exceeded 3 years prior to BRONJ diagnosis. DISCUSSION The results from this study suggest that the relative frequency of osteoporosis patients on oral BPs suffering from BRONJ is higher than previously reported. There is an urgent need to substantiate epidemiological characteristics of BRONJ in large cohorts of individuals.

Ceramic scaffolds produced by computer-assisted 3D printing and sintering: Characterization and biocompatibility investigations

Hydroxyapatite (HAP) and tricalcium phosphate (TCP) are two very common ceramic materials for bone replacement. However, in general HAP and TCP scaffolds are not tailored to the exact dimensions of the defect site and are mainly used as granules or beads. Some scaffolds are available as ordinary blocks, but cannot be customized for individual perfect fit. Using computer-assisted 3D printing, an emerging rapid prototyping technique, individual three-dimensional ceramic scaffolds can be built up from TCP or HAP powder layer by layer with subsequent sintering. These scaffolds have precise dimensions and highly defined and regular internal characteristics such as pore size. External shape and internal characteristics such as pore size can be fabricated using Computer Assisted Design (CAD) based on individual patient data. Thus, these scaffolds could be designed as perfect fit replacements to reconstruct the patients skeleton. Before their use as bone replacement materials in vivo, in vitro testing of these scaffolds is necessary. In this study, the behavior of human osteoblasts on HAP and TCP scaffolds was investigated. The commonly used bone replacement material BioOss(R) served as control. Biocompatibility was assessed by scanning electron microscopy (SEM), fluorescence microscopy after staining for cell vitality with fluorescin diacetate (FDA) and propidium iodide (PI) and the MTT, LDH, and WST biocompatibility tests. Both versions were colonised by human osteoblasts, however more cells were seen on HAP scaffolds than TCP scaffolds. Cell vitality staining and MTT, LDH, and WST tests showed superior biocompatibility of HAP scaffolds to BioOss, while BioOss was more compatible than TCP. Further experiments are necessary to determine biocompatibility in vivo. Future modifications of 3D printed scaffolds offer advantageous features for Tissue Engineering. The integration of channels could allow for vascular and nerve ingrowth into the scaffold. Also the complex shapes of convex and concave articulating joint surfaces maybe realized with these rapid prototyping techniques.

The battle against multi-resistant strains: Renaissance of antimicrobial essential oils as a promising force to fight hospital-acquired infections

Hospital-acquired infections and antibiotic-resistant bacteria continue to be major health concerns worldwide. Particularly problematic is methicillin-resistant Staphylococcus aureus (MRSA) and its ability to cause severe soft tissue, bone or implant infections. First used by the Australian Aborigines, Tea tree oil and Eucalyptus oil (and several other essential oils) have each demonstrated promising efficacy against several bacteria and have been used clinically against multi-resistant strains. Several common and hospital-acquired bacterial and yeast isolates (6 Staphylococcus strains including MRSA, 4 Streptococcus strains and 3 Candida strains including Candida krusei) were tested for their susceptibility for Eucalyptus, Tea tree, Thyme white, Lavender, Lemon, Lemongrass, Cinnamon, Grapefruit, Clove Bud, Sandalwood, Peppermint, Kunzea and Sage oil with the agar diffusion test. Olive oil, Paraffin oil, Ethanol (70%), Povidone iodine, Chlorhexidine and hydrogen peroxide (H(2)O(2)) served as controls. Large prevailing effective zones of inhibition were observed for Thyme white, Lemon, Lemongrass and Cinnamon oil. The other oils also showed considerable efficacy. Remarkably, almost all tested oils demonstrated efficacy against hospital-acquired isolates and reference strains, whereas Olive and Paraffin oil from the control group produced no inhibition. As proven in vitro, essential oils represent a cheap and effective antiseptic topical treatment option even for antibiotic-resistant strains as MRSA and antimycotic-resistant Candida species.

Platelet‐rich fibrin membranes as scaffolds for periosteal tissue engineering

OBJECTIVES Platelet-rich fibrin (PRF)-based membranes have been used for covering alveolar ridge augmentation side in several in vivo studies. Few in vitro studies on PRF and no studies using human periosteal cells for tissue engineering have been published. The aim is a comparison of PRF with the commonly used collagen membrane Bio-Gide as scaffolds for periosteal tissue engineering. MATERIAL AND METHODS Human periosteal cells were seeded on membrane pieces (collagen [Bio-Gide] and PRF) at a density of 10(4) cells/well. Cell vitality was assessed by fluorescein diacetate (FDA) and propidium iodide (PI) staining, biocompatibility with the lactate dehydrogenase (LDH) test and proliferation level with the MTT, WST and BrdU tests and scanning electron microscopy (SEM). RESULTS PRF membranes showed slightly inferior biocompatibility, as shown by the LDH test. The metabolic activity measured by the MTT and WST tests was higher for PRF than for collagen (BioGide). The proliferation level as measured by the BrdU test (quantitative) and SEM examinations (qualitative) revealed higher values for PRF. CONCLUSION PRF appears to be superior to collagen (Bio-Gide) as a scaffold for human periosteal cell proliferation. PRF membranes are suitable for in vitro cultivation of periosteal cells for bone tissue engineering.

Facial attractiveness: visual impact of symmetry increases significantly towards the midline.

Symmetry is thought to be a major prerequisite for an attractive face. Many faces are not symmetric, yet are still regarded as beautiful. What role, then, does asymmetry play in the perception of beauty? We studied the assessment of computer-manipulated images by independent judges (n = 200–250): part A: nevi located at different positions; part B: standardized changes of the orbital region. The results showed that slight lateral orbital and facial asymmetry does not impair attractiveness at all and that asymmetries close to the midline are significantly less attractive than those affecting the lateral aspect of the face (P < 0.001). A single nevus which is located laterally on the face is significantly more attractive than a nevus close to the midline (P < 0.001). Faces with a completely symmetric bilateral pair of nevi in the same lateral positions (perceived as attractive when alone), received the worst ratings (P < 0.001). Symmetry is a characteristic of the attractive face, but there are exceptions to the rule. Under certain conditions symmetry can be completely unattractive. The visual impact of symmetry on the perception of beauty increases significantly when approaching the midline.

Endocultivation: 3D printed customized porous scaffolds for heterotopic bone induction

The aim of this study was to evaluate the ability of computer assisted designed (CAD) synthetic hydroxyapatite and tricalciumphosphate blocks to serve as precise scaffolds for intramuscular bone induction in a rat model. A central channel to allow for vessel pedicle or nerve integration was added. Natural bovine hydroxyapatite blocks served as controls to evaluate and compare biocompatibility of the new matrices. Individually designed 3D-printed rounded and porous hydroxyapatite (HA) and tricalcium phosphate (TCP) blocks were placed in pouches in the Musculus latissimus dorsi in 12 Lewis rats bilaterally. Bovine hydroxyapatite blocks with and without a central channel served as controls. Simultaneously, 200 microg rhBMP-2 in 1 ml sodium chloride was injected on both sides. For 8 weeks, bone generation was monitored by computer tomography and fluorescence labeling. The increase rates of bone density in CT examinations were higher in the HA groups (184-220 HU 8 weeks after implantation) compared to the TCP group (18 HU; p<0.0001). Microradiography and fluorescence microscopy 8 weeks after implantation showed new bone formation for all materials tested. For all scaffolds, toluidine staining revealed vital bone directly on the scaffold materials but also in the gaps between. It can be concluded from our data that the specially shaped hydroxyapatite and tricalcium phosphate blocks tested against the bovine hydroxyapatite blocks showed good biocompatibility and osteoinductivity in vivo. Further studies should explore if the stability of the individually designed blocks is sufficient to cultivate larger replacements without an external matrix for support.

Penicillin compared with other advanced broad spectrum antibiotics regarding antibacterial activity against oral pathogens isolated from odontogenic abscesses

OBJECTIVES We examined the spectrum of oral pathogens found in odontogenic abscesses and their susceptibility to penicillin as well as to amoxicillin with clavulanic acid, doxycycline, clindamycin and moxifloxacin. The in vitro results were compared with clinical observations. PATIENTS AND METHODS One hundred and eighty eight swabs were obtained from 94 patients with odontogenic abscesses. Bacterial strains were isolated for susceptibility tests. The same patients were investigated for their clinical outcome after standard therapy. RESULTS A total of 517 bacterial strains were isolated from 94 patients. Ninety eight per cent of abscesses were polymicrobial. The most prevalent bacteria were Viridans streptococci representing 54% of the aerobic/facultative anaerobic bacteria. Prevotella spp. comprised 53% of the anaerobes. No multiresistant strains were detected. Susceptibility testing revealed a sensitivity of over 99% of aerobes/facultative aerobes and 96% of anaerobes sensitivity for moxifloxacin. The corresponding values for penicillin were lowest at 61% and 79%, respectively. In the clinical collective, patients with minor abscesses and no risk of further progression received surgical treatment without antibiotics (36%). Penicillin was administered additionally in 30%. Amoxicillin with clavulanic acid was given in 18% and clindamycin in 15%. Ninety two of the 94 patients showed significant recovery with the described treatment. Only in two cases was a change to the latest broader spectrum antibiotics necessary. CONCLUSION In contrast to the moderate in vitro results, penicillin successfully treated the pathogens derived from odontogenic abscess sufficiently when adequate surgical treatment was provided. One third of the patients was treated successfully with incision and drainage only. We suggest that one good reason for its clinical efficacy is the susceptibility of the dominant aerobe/facultative aerobe and anaerobe strains to penicillin.