73 research outputs found
[Regeneration instead of reparation : A critical review of the autogenous bone transplant as "golden standard" of reconstructive oral surgery.]
No full textAutogenous bone transfer is still regarded as the "golden standard" for many indications in oral and cranio-maxillofacial surgery. In this overview, the status of the autogenous bone is re-evaluated under consideration of current research results, clinical long-term studies, risks and safety of the patient as well as the costs. Due to the further development of modern bone substitute materials, which reveal in parts superior long-term results for special indications, the routine use of autogenous bone has to be critically reviewed
Incidence and Risk Factors of Bisphosphonate-Related Osteonecrosis of the Jaw in Multiple Myeloma Patients Having Undergone Autologous Stem Cell Transplantation
No full textBackground: Bisphosphonate-related osteonecrosis of the jaw (BRONJ) is a severe complication of bisphosphonate therapy. Due to their long survival and subsequently high cumulative doses of bisphosphonates, multiple myeloma patients have the highest risk of developing BRONJ of all patients treated with bisphosphonates. The purpose of the present study was to evaluate the incidence and risk factors for BRONJ in multiple myeloma patients after high-dose chemotherapy and autologous stem cell transplantation (ASCT). Patients and Methods: We retrospectively analyzed the data of 120 multiple myeloma patients after high-dose chemotherapy and ASCT treated with bisphosphonates and assessed the incidence and risk factors of BRONJ. Results: Of the 120 patients, 23 (19%) developed BRONJ. 6 patients suffered several BRONJ events, resulting in a total incidence of 23%. The risk for BRONJ was significantly higher for patients with rheumatism and recent dental manipulations. Furthermore, the number of previous bisphosphonate rotations, the duration of bisphosphonate therapy, and the type and cumulative dose of bisphosphonate used were associated with the incidence of BRONJ. Conclusion: Our study is the first to determine the risk of BRONJ in a homogeneous group of multiple myeloma patients treated with high-dose chemotherapy and ASCT
Dose-dependent new bone formation by extracorporeal shock wave application on the intact femur of rabbits
No full textBackground: Whereas various molecular working mechanisms of shock waves have been demonstrated, no study has assessed in detail the influence of varying energy flux densities (EFD) on new bone formation in vivo. Methods: Thirty Chinchilla bastard rabbits were randomly assigned to 5 groups (EFD 0.0, 0.35, 0.5, 0.9 and 1.2 mJ/mm(2)) and treated with extracorporeal shock waves at the distal femoral region (1,500 pulses; 1 Hz frequency). To investigate new bone formation, animals were injected with oxytetracycline at days 5-9 after shock wave application and sacrificed on day 10. Histological sections of all animals were examined using broad-band epifluorescent illumination, contact microradiography and Giemsa-Eosin staining. Results: Application of shock waves induced new bone formation beginning with 0.5 mJ/mm(2) EFD and increasing with 0.9 mJ/mm(2) and 1.2 mJ/mm(2). The latter EFD resulted in new bone formation also on the dorsal cortical bone; cortical fractures and periosteal detachment also occurred. Conclusion: Here, for the first time, a threshold level is presented for new bone formation after applying shock waves to intact bone in vivo. The findings of this study are of considerable significance for preventing unwanted side effects in new approaches in the clinical application of shock waves. Copyright (c) 2008 S. Karger AG, Basel
A novel high-resolution magnetic resonance imaging microscopy coil as an alternative to the multislice computed tomography in postoperative imaging of orbital fractures and computer-based volume measurement.
No full textBACKGROUND: Multislice computed tomography (MSCT) has been the modality of choice for postoperative detailed imaging of orbital trauma. Unfortunately, it involves extensive exposition of the lens to radiation, especially when taking multiple readings. Also, it holds beam hardening effects and limited imaging (delineation) of the reconstruction material. Alternative conventional magnetic resonance imaging (MRI) head coils (MRIhc) present reduced differentiation of anatomic structures caused by low signal and artifact appearance. A substantially improved depiction is made possible by a newly introduced MRI microscopy coil (MRImc), used for the first time in this field. PATIENTS AND METHODS: In this prospective study, 32 patients with extended orbital wall fractures (n = 36) were treated surgically using a polydioxanonsulfate (PDS) foil after reconstruction. Postoperatively, imaging was performed using MRImc, conventional MRI, and MSCT to evaluate the different imaging techniques. RESULTS: The position of the PDS foil could precisely be depicted in 29 of 36 fractures by MRImc, whereas by conventional MRI and MSCT the reconstruction material could only be detected in 25 and 24 of 36 fractures, respectively. In contrast to MRIhc, the new microscopy coil allows fast and high resolution imaging and therefore a clear differentiation of eventual postoperative complications (eg, dislocation of the PDS foil with secondary soft tissue entrapment resulting in limitation of ocular movements or enophthalmos). In 13 long lasting symptomatic cases, revision surgery could be avoided because of regular MRImc findings, apart from muscle swelling and hematoma. In 11 cases of inadequate PDS foil position resulting in revision, the mean volume of displaced tissue (VDT) of 0.62 cm3 correlated significantly to an enophthalmos of more than 2 mm. CONCLUSION: In this pilot study, MRImc proved to be highly superior to MRIhc and MSCT in postsurgical orbital imaging, especially for decision making regarding revision surgery
Can the inferior alveolar nerve be used as a marker in frozen section for free margin control after segmental mandibulectomy in tumour ablation?
No full textThis study critically assessed the possibility of tumour spread along the inferior alveolar nerve (IAN) and its sensitivity as an intraoperative marker for clear bony margin control in frozen section during segmental mandibulectomy. Fifteen patients with oral squamous cell carcinoma (OSCC) involving the mandible and requiring a segmental mandibulectomy were included in this prospective trial. The ends of the IAN were analyzed using quick section analysis and the results compared with those of the definite pathological report. Nerve tissue could be identified in 25 of the 27 specimens collected. No specimen revealed tumour invasion. All histological diagnoses were finally confirmed. Three positive bony margins with microscopic carcinoma infiltrates were found, whereas corresponding nerve tissue did not confirm tumour invasion. This study supports the assumption that the pattern of tumour invasion is rarely primarily along the IAN in OSCC involving the mandible. Quick section analysis of the nerve tissue alone is therefore not a valid marker for intraoperative bony margin control. However, it can be used as an additional intraoperative diagnostic tool combined with other methods in rare cases of primary tumour spread along the IAN. A review of current knowledge regarding bony margin control published in the literature is provided
In vivo tetracycline labeling of bone: an intraoperative aid in the surgical therapy of osteoradionecrosis of the mandible.
No full textIn this technical approach, we demonstrate that preoperative tetracycline administration helps distinguish between viable and necrotic bone in osteoradionecrosis (ORN) during surgery by exciting tetracycline fluorescence by black light. The difficult aspect of the operative approach lies in the decision of the extent of the debridement in order to prevent an iatrogenic fracture or progression of ORN. With this technique, vital bone, in contrast to necrotic bone, showed detectable fluorescence. Therefore, tetracycline fluorescence labeling may be used in attempts to facilitate the intraoperative decision making in the surgical therapy of osteoradionecrosis
Comparison of 16-slice MSCT and MRI in the assessment of squamous cell carcinoma of the oral cavity.
No full textThe goal of this retrospective study was to assess the accuracy of 16-slice multislice CT (MSCT) and MRI in staging of patients with primary squamous cell carcinoma (SCC) of the oral cavity. Fifty-two patients with histologically proven primary SCC were examined with contrast enhanced MSCT and MRI at 1.5 T with a combined head and surface neck coil. Image modalities were evaluated in a blinded fashion by two radiologists and an oral-maxillofacial surgeon in consensus concerning tumour depiction, local tumour infiltration and cervical lymph node metastases. Results of the radiological assessment were correlated with the intraoperative and histopathological findings in all patients. 36 of 52 primary tumours (69.2%) were depicted by MSCT while 44 were localized by MRI (84.6%). Regarding muscle infiltration MRI versus MSCT had a sensitivity of 81.8% versus 72.7%, but a low specificity and an accuracy of 63.4% versus 61% and 67.3% versus 63.5%, respectively, were found. There was a trend towards a better detection of bony infiltration by MRI than MSCT with a sensitivity of 100% versus 71.4%, a specificity of 93.3% versus 95.5% and an accuracy 94.2% versus 92.3%, respectively. Detection of cervical lymph node involvement was similar for MRI and MSCT with a sensitivity of 84.2% and 78.9%, a specificity of 63.6% and 75.7% and an accuracy of 71.1% and 76.9%, respectively. For N-staging both methods failed to detect small metastasis. For T-staging MRI was superior to MSCT, because there was a tendency to underestimate the tumour size by MSCT more often (19.4% versus 6.8% by MRI). Therefore, pre-operative MRI is recommended as the basic imaging modality of choice for treatment planning of oral SCC. MSCT is a valid alternative imaging method especially in cases with low patient compliance
Dose-dependent new bone formation by extracorporeal shock wave application on the intact femur of rabbits.
No full textBACKGROUND: Whereas various molecular working mechanisms of shock waves have been demonstrated, no study has assessed in detail the influence of varying energy flux densities (EFD) on new bone formation in vivo. METHODS: Thirty Chinchilla bastard rabbits were randomly assigned to 5 groups (EFD 0.0, 0.35, 0.5, 0.9 and 1.2 mJ/mm2) and treated with extracorporeal shock waves at the distal femoral region (1,500 pulses; 1 Hz frequency). To investigate new bone formation, animals were injected with oxytetracycline at days 5-9 after shock wave application and sacrificed on day 10. Histological sections of all animals were examined using broad-band epifluorescent illumination, contact microradiography and Giemsa-Eosin staining. RESULTS: Application of shock waves induced new bone formation beginning with 0.5 mJ/mm2 EFD and increasing with 0.9 mJ/mm2 and 1.2 mJ/mm2. The latter EFD resulted in new bone formation also on the dorsal cortical bone; cortical fractures and periosteal detachment also occurred. CONCLUSION: Here, for the first time, a threshold level is presented for new bone formation after applying shock waves to intact bone in vivo. The findings of this study are of considerable significance for preventing unwanted side effects in new approaches in the clinical application of shock waves
A strategy to establish a gene-activated matrix on titanium using gene vectors protected in a polylactide coating.
No full textBioactive implants are promising tools in regenerative medicine. Here we describe a versatile procedure for preparing a gene-activated matrix on titanium. Lyophilized copolymer-protected gene vectors (COPROGs) suspended in poly(d,l-lactide) (PDLLA) solutions in ethyl acetate were used to varnish solid surfaces. The gene-activated PDLLA surfaces were first established on polypropylene 96-well plates. Vector release from these surfaces in aqueous buffer, cell viability and gene transfer efficiency to NIH 3T3 fibroblasts was strongly dependent on the vector dose and its ratio to PDLLA film thickness. A detailed analysis of these relationships allowed establishing correlations which can be used to calculate suitable combinations of COPROGs and PDLLA yielding optimal gene transfer efficiency. This was verified with COPROG-activated PDLLA coatings on titanium foils. HEK 293 and mesenchymal stem cells expressed the BMP-2 gene comprised in the gene-activated surface in a manner that was consistent with the predicted dose-response and toxicity profiles found in NIH 3T3 cells. The systematic procedure presented here for identifying optimal coating compositions can be applied to any combination of vector type and coating material
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