Joerg Wiltfang

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.

Sensor-based laser ablation for tissue specific cutting: an experimental study

The interaction of laser light and tissue causes measurable phenomenons. These phenomenons can be quantified and used to control the laser drilling within a feedback system. Ten halves of dissected minipig jaws were treated with an Er:YAG laser system controlled via a feedback system. Sensor outputs were recorded and analyzed while osteotomy was done. The relative depth of laser ablation was calculated by 3D computed tomography and evaluated histologically. The detected signals caused by the laser–tissue interaction changed their character in a dramatic way after passing the cortical bone layer. The radiological evaluation of 98 laser-ablated holes in the ten halves showed no deeper ablation beyond the cortical layer (mean values: 97.8%). Histologically, no physical damage to the alveolar nerve bundle was proved. The feedback system to control the laser drilling was working exactly for cortical ablation of the bone based on the evaluation of detected and quantified phenomenon related to the laser–tissue interaction.

A clinically-feasible protocol for using human platelet lysate and mesenchymal stem cells in regenerative therapies

The transplantation of human stem cells seeded on biomaterials holds promise for many clinical applications in cranio-maxillo-facial tissue engineering and regenerative medicine. However, stem cell propagation necessary to produce sufficient cell numbers currently utilizes fetal calf serum (FCS) as a growth supplement which may subsequently transmit animal pathogens. Human platelet lysate (HPL) could potentially be utilized to produce clinical-grade stem cell-loaded biomaterials as an appropriate FCS substitute that is in line with clinically-applicable practice. The goal of this study was to investigate whether HPL can be successfully used to propagate human mesenchymal stem cells (HMSCs) seeded on clinically-approved collagen materials under clinically-applicable conditions using FCS as a control. HMSCs were isolated from bone marrow and cultured in the presence of 10% FCS or 10% HPL. Characterization of HMSCs was performed by flow cytometry and through osteogenic and adipogenic differentiation assays. Proliferative capacity of HMSCs on both matrices was investigated by mitochondrial dehydrogenase assays (WST) and tissue coverage scanning electron microscopy (SEM). The isolated HMSC differentiated into osteogenic and adipogenic cells authenticating the multipotentiality of the HMSCs. WST tests and the SEM images demonstrated that HPL was generally superior to FCS in promoting growth of seeded HMSCs. For all other tests HPL supported HMSCs at least equal to FCS. In conclusion, HPL is an effective growth factor to allow expansion of clinical-grade HMSCs on clinically-approved biomaterials for maxillofacial and oral implantology applications.

Validation of histologic changes induced by external irradiation in mandibular bone. An experimental animal model

The present experimental study sought to determine the effect of high-dose irradiation on the rat mandible in order to establish an experimental model of radiogenic bone damage. The left mandibles of 20 adult Wistar rats were irradiated (single fraction 1500cGy, total dose 60Gy) by means of a hypofractionated stereotactic radiotherapy (hfSRT) over a period of 6 weeks. Follow-up was 6 weeks (group 1, n=10) and 12 weeks (group 2, n=10). The contralateral mandibles as well as 5 non-irradiated animals served as controls. Primary endpoints were fibrosis, loss of cell count, decreased immunohistochemical labelling for bone morphogenetic protein-2 (BMP-2) and osteocalcin as well as increased expression of transforming growth factor (TGF-beta). Cell loss, progressive fibrosis, and focal necrosis were detected in all irradiated sites. Quantitative measurement revealed 32.0+/-8.7% and 37.3+/-9.5% empty osteocyte lacunae for groups 1 and 2 resp., compared to 16.3+/-4.7% and 18.9+/-4.9% on the contralateral side and 7.9+/-1.7% for unirradiated controls (Mann-Whitney U test; p<.01). BMP-2 and osteocalcin labelling showed a marked decrease in irradiated and contralateral sides while TGF-beta was expressed strongly in irradiated sites only (for all p<.05). External hypofractionated irradiation with a total dose of 60Gy is feasible in rats and yields all histologic changes attributed to osteoradionecrosis (ORN) after a follow-up of 6 weeks. The irradiation protocol is suitable for an assessment of regenerative options in severe radiogenic bone damage. As a split mouth design entails major inaccuracies healthy animals have to be used as controls.

Comparison of two different absorbable membranes for the coverage of lateral osteotomy sites in maxillary sinus augmentation: A preliminary study

INTRODUCTION Barrier membranes, both absorbable and non-absorbable, have been used in sinus augmentation for many years. Some years ago, a new autologous blood substrate called Platelet-Rich-Fibrin (PRF) was introduced, and to date, the supporting effect on bone regeneration has been controversial. This study aimed to evaluate the effect of PRF on bone regeneration when used as a barrier membrane at the lateral osteotomy site in sinus augmentation. MATERIAL AND METHODS Twelve sinuses from six patients requiring bilateral sinus floor augmentation were treated with a two-stage surgical technique using sinus augmentation and implant placement after 5 months. The sinuses were grafted with autologous bone and bone-substitute material (Bio-Oss(®)) mixed in a 1:1 ratio and were covered in a randomized split-mouth design with a PRF or a conventional collagen membrane (Bio-Gide(®)), respectively. Five months later threaded titanium dental implants were inserted and bone specimens harvested with a trephine burr were evaluated histomorphometrically. RESULTS Bone quality seemed to be equal at both sites of the grafted sinuses. Mean vital bone formation after 5 months was 17.0% and 17.2%, for the PRF and collagen sites, respectively. The mean of residual bone-substitute was 15.9% and 17.3% for PRF and collagen, respectively. No local complications, such as dehiscences or membrane exposures, were detected at either site in any of the treated patients. After 12 months all implants reached primary stability in the augmented maxillary sinus floor without any peri-implant tissue inflammation. CONCLUSIONS Within the limits of the study the coverage of the lateral sinus window with two different absorbable membranes has been shown to result in a similar amount of vital bone formation and residual bone-substitute.

Expression of melanoma-associated antigens in oral squamous cell carcinoma

BACKGROUND Melanoma-associated antigens-A (MAGE-A) are expressed in a variety of tumors but not in normal tissues. Thus, their detection is highly specific to cancer cells, which makes them potential targets for the diagnosis, prognosis and also immunotherapy of neoplastic diseases. METHODS To determine the expression pattern and potential role of MAGE-A antigens in oral squamous cell carcinoma (OSCC), expression patterns of MAGE-A1-A6 and A12 were analyzed in 55 OSCC and 20 healthy oral mucosa using high-sensitive reverse transcription-nested polymerase chain reaction (RT-nPCR). RESULTS The 85.45% of tumor specimens expressed at least one of these genes. A significant correlation between the expression of MAGE-A1-A6 and A12 and malignancy was ascertained (P = 0.0001). On the contrary, none of the normal mucosal specimens expressed one of the MAGE-A subtypes. Antigen expression did not correlate with clinicopathological parameters, such as TNM classification, grading and clinical stage of OSCC. CONCLUSIONS Multiple simultaneous detection of MAGE-A1-A6 and A12 expression has been found to be more specific and sensitive than the detection of single MAGE-A antigen for the diagnostic and prognostic evaluation of OSCC. In addition, monitoring the expression of several MAGE-A subtypes may determine suitable immunotherapeutic targets. Subsequently, coexpressed genes may be warranted for developing polyvalent vaccines.

Tissue Engineering of a Vascularized Bone Graft of Critical Size with an Osteogenic and Angiogenic Factor-Based In Vivo Bioreactor

Engineering a large vascularized bone graft is a much greater challenge than engineering small bone tissues. Although this is essentially feasible through an osteogenic factor-based in vivo bioreactor technique, the ossification needs improving. This study was aimed to investigate the possibility and efficacy of ectopic cultivation of sizeable bone grafts with large angiogenic and osteogenic factor-loaded natural bovine bone mineral (NBBM) scaffolds. For this purpose, six groups of sizeable composite scaffolds were constructed, consisting of a titanium mesh cage of NBBM or a mixture of NBBM/autogenous bone particles (AB), which were preloaded with 660 μg recombinant human bone morphogenetic protein-7 (rhBMP-7) and/or 4 μg recombinant human vascular endothelial growth factor165 (rhVEGF165). The scaffolds were implanted in bilateral latissimus dorsi muscles in eight pigs to construct in vivo bioreactors. Sequential fluorescence labeling was then applied to trace bone formation at the early stage. The implan...

Influence of Early Hard Palate Closure in Unilateral and Bilateral Cleft Lip and Palate on Maxillary Transverse Growth During the First Four Years of Age

OBJECTIVE To evaluate and compare the effects of early primary closure of the hard palate on the anterior and posterior width of the maxillary arch in children with bilateral (BCLP) and unilateral (UCLP) cleft lip and palate during the first 4 years of life. DESIGN A retrospective, mixed-longitudinal study. SETTING Cleft Palate Center of the University of Erlangen-Nuremberg. SUBJECTS AND METHODS The present investigation analyzes longitudinally 42 children with UCLP and 8 children with BCLP between 1996 and 2000 with early simultaneous primary closure of lip and hard palate (4 to 5 months). Palatal arch width was measured on dental casts with a computer-controlled three-dimensional digitizing system, and their growth velocities were calculated from consecutive periods (mean follow-up 39 months). Differences in growth velocities were compared with those of 25 children with UCLP and 15 children with BCLP with delayed closure of hard palate (12 to 14 months). RESULTS AND CONCLUSIONS There was no significant difference in terms of anterior and posterior maxillary width between early and delayed closure of hard palate within the first 4 years of life.

Guided bone regeneration: dynamic procedures versus static shielding in an animal model.

Due to its osteoinductive potential, the periosteum plays a crucial role in the process of neoosteogenesis. Therefore, periosteal elevation can lead to new bone formation in an artificially created space. In this study, we compared dynamic periosteal elevation with static shielding in an animal experiment. Different elevation/shielding heights of 5, 10, and 15 mm were tested with regard to various consolidation periods. Histological analysis, histomorphometry, and microradiography were used to measure the quantity and quality of the newly formed bone. No significant differences regarding bone quantity or quality were found between the two techniques. The cumulative results for the bone regeneration in the space created by distraction/elevation were about 66% in the dynamic and 67% in static procedure. The main advantages of both techniques are minimal invasion and low morbidity. In terms of clinical applications, periosteal elevation could be applied in cranio-maxillofacial surgery, in pre-implant augmentation and in reconstructive surgery.

Elevation of the maxillary sinus membrane for de-novo bone formation: First results of a prospective study in humans

PURPOSE Sinus floor elevation via the lateral window approach represents a reliable technique for bone augmentation in the atrophic posterior maxilla. It is known that sinus membrane elevation leads to new bone formation. This prospective clinical study compared a specific technique in sinus membrane elevation with a conventional sinus floor augmentation (xenogenous/autogenous bone) in a human split mouth model. METHODS Five edentulous patients with highly atrophic posterior maxillae were included in this study. On one maxillary side a degradable PDLLA-membrane was placed to create a space underneath the sinus membrane. Contralateral a mixture of autogenous and xenogenous bone was used for sinus floor augmentation. A two-stage procedure was carried out. The following variables were assessed: bone regeneration on cone-beam computed tomography (cone-beam CT), implant success, prosthetic comfort and patient satisfaction. Bone biopsies were taken with simultaneous implant placement. The samples were histologically analyzed. RESULTS Cone-beam CTs revealed new bone formation on both sides. Thirty implants were placed, 15 in the augmented region and 15 in the non-augmented side. Thirty bone biopsies were taken and evaluated. Vital new bone was detected on the experimental side (osteoinductivity). On the conventional side a mixture of autogenous and residual bone substitute material was seen (osteoconductivity). Implant survival was 100% so far. Patients satisfaction was high and prosthetic complications were not encountered. CONCLUSION As it provides the highest rate of bone formation, autogenous bone in combination with bone substitute material can be considered as a very reliable standard procedure in sinus floor augmentation. The specific sinus membrane elevation technique as presented here showed satisfying results and might be a suitable alternative for maxillary sinus augmentation.