Current trends and future perspectives of bone substitute materials - from space holders to innovative biomaterials

An autologous bone graft is still the ideal material for the repair of craniofacial defects, but its availability is limited and harvesting can be associated with complications. Bone replacement materials as an alternative have a long history of success. With increasing technological advances the spectrum of grafting materials has broadened to allografts, xenografts, and synthetic materials, providing material specific advantages. A large number of bone-graft substitutes are available including allograft bone preparations such as demineralized bone matrix and calcium-based materials. More and more replacement materials consist of one or more components: an osteoconductive matrix, which supports the ingrowth of new bone; and osteoinductive proteins, which sustain mitogenesis of undifferentiated cells; and osteogenic cells (osteoblasts or osteoblast precursors), which are capable of forming bone in the proper environment. All substitutes can either replace autologous bone or expand an existing amount of autologous bone graft. Because an understanding of the properties of each material enables individual treatment concepts this review presents an overview of the principles of bone replacement, the types of graft materials available, and considers future perspectives. Bone substitutes are undergoing a change from a simple replacement material to an individually created composite biomaterial with osteoinductive properties to enable enhanced defect bridging.

Osseointegration of zirconia implants compared with titanium: an in vivo study

Background

Titanium and titanium alloys are widely used for fabrication of dental implants. Since the material composition and the surface topography of a biomaterial play a fundamental role in osseointegration, various chemical and physical surface modifications have been developed to improve osseous healing. Zirconia-based implants were introduced into dental implantology as an altenative to titanium implants. Zirconia seems to be a suitable implant material because of its tooth-like colour, its mechanical properties and its biocompatibility. As the osseointegration of zirconia implants has not been extensively investigated, the aim of this study was to compare the osseous healing of zirconia implants with titanium implants which have a roughened surface but otherwise similar implant geometries.

Methods

Forty-eight zirconia and titanium implants were introduced into the tibia of 12 minipigs. After 1, 4 or 12 weeks, animals were sacrificed and specimens containing the implants were examined in terms of histological and ultrastructural techniques.

Results

Histological results showed direct bone contact on the zirconia and titanium surfaces. Bone implant contact as measured by histomorphometry was slightly better on titanium than on zirconia surfaces. However, a statistically significant difference between the two groups was not observed.

Conclusion

The results demonstrated that zirconia implants with modified surfaces result in an osseointegration which is comparable with that of titanium implants.

A histomorphometric meta-analysis of sinus elevation with various grafting materials

Several grafting materials have been used in sinus augmentation procedures including autogenous bone, demineralized freeze-dried bone (DFDBA), hydroxyapatite, beta-tricalcium phosphate (beta-TCP), anorganic deproteinized bovine bone and combination of these and others. Up to now a subject of controversy in maxillofacial surgery and dentistry is, what is the most appropriate graft material for sinus floor augmentation.

PURPOSE

The aim of this study is to provide a body of evidence-based data regarding grafting materials in external sinus floor elevation concerning the fate of the augmented material at the histomorphological level, through a meta-analysis of the available literature.

MATERIALS AND METHODS

The literature searches were performed using the National Library of Medicine. The search covered all English and German literature from 1995 until 2006. For analyzing the amount of bone the parameter "Total Bone Volume" (TBV) was assessed. TBV is determined as the percentage of the section consisting of bone tissue.

RESULTS

In a relatively early phase after implantation the autogenous bone shows the highest TBV values. Interestingly, the different TBV levels approximate during the time. After 9 months no statistically significant differences can be detected between the various grafting materials.

CONCLUSION

From a clinical point of view, the use of autogenous bone is advantageous if a prosthetic rehabilitation (with functional loading) is expected within 9 months. In other cases the use of anorganic deproteinized bovine bone in combination with autogenous bone seems to be preferable. Donor side morbidity is ignored in this conclusion.

Oral cancer malnutrition impacts weight and quality of life

Diet is important for both quality of life (QoL) and survival of patients with oral cancer. Their intake of food is impeded by functional restrictions in chewing and swallowing. In the DÖSAK REHAB STUDY 1652 patients from 38 hospitals within the German-language area of Germany; Austria and Switzerland were examined with regard to functional and psychological variables having an impact on diet. Chewing and swallowing are correlated with mobility of the tongue and the mandible as well as opening of the mouth. Thirty five percent of the patients lost weight; 41% maintained their weight and 24% gained weight. The QoL of patients who were able to maintain their weight and of those who gained weight was significantly better than that of patients who lost weight. A normal diet was important for maintaining weight. Mashed food; liquid food and loss of appetite were closely associated with loss of weight; although it was possible for nutritional counseling and dietary support to be implemented particularly favorably in this respect. Due to problems with eating patients' strength deteriorated; thus restricting activity. Radiotherapy had a negative impact on diet and weight. It influenced sense of taste; dryness of the mouth; swelling and discomfort when ingesting food. Pain and scars in the region of the operation also cause patients to dislike hard; spicy and sour food. Support from a nutritional counselor in implementing a calorie-rich diet remedied this and such support needs to be integrated into patient management. The fact that a poor nutritional status is of such great importance is well-known; but what is often lacking is the systematic implementation of continued professional nutritional counseling over a long period of time; weight control and psycho-social support of the operated patients; particularly those who also have had radiotherapy.

TCP is hardly resorbed and not osteoconductive in a non-loading calvarial model

Tricalciumphosphate (TCP) has been used as a ceramic bone substitute material in the orthopedic field as well as in craniofacial surgery. Some controversies exist concerning the osteoconductive potential of this material in different implantation sites. This study was designed to evaluate the biological response of calvarial bone towards TCP granules under non-loading conditions to assess the potential of TCP as a biodegredable and osteoconductive bone substitue material for the cranial vault. Full-thickness non-critical size defects were made bilaterally in the calvaria of 21 adult Wistar rats. One side was filled by TCP granules, the contralateral side was left empty and used as a control. Animals were sacrified in defined time intervals up to 6 months. Bone regeneration was analyzed with special respect toward the micromorphological and microanalytical features of the material-bone interaction by electron microscopy and electron diffraction analysis. Histologic examination revealed no TCP degradation even after 6 months of implantation. In contrast, a nearly complete bone regeneration of control defects was found after 6 months. At all times TCP was surrounded by a thin fibrous layer without presence of osteoblasts and features of regular mineralization. As far as degradation and substitution are concerned, TCP is a less favourable material tinder conditions of non-loading.

Behavior of osteoblastic cells cultured on titanium and structured zirconia surfaces

BACKGROUND

Osseointegration is crucial for the long-term success of dental implants and depends on the tissue reaction at the tissue-implant interface. Mechanical properties and biocompatibility make zirconia a suitable material for dental implants, although surface processings are still problematic. The aim of the present study was to compare osteoblast behavior on structured zirconia and titanium surfaces under standardized conditions.

METHODS

The surface characteristics were determined by scanning electron microscopy (SEM). In primary bovine osteoblasts attachment kinetics, proliferation rate and synthesis of bone-associated proteins were tested on different surfaces.

RESULTS

The results demonstrated that the proliferation rate of cells was significantly higher on zirconia surfaces than on titanium surfaces (p < 0.05; Student's t-test). In contrast, attachment and adhesion strength of the primary cells was significant higher on titanium surfaces (p < 0.05; U test). No significant differences were found in the synthesis of bone-specific proteins. Ultrastructural analysis revealed phenotypic features of osteoblast-like cells on both zirconia and titanium surfaces.

CONCLUSION

The study demonstrates distinct effects of the surface composition on osteoblasts in culture. Zirconia improves cell proliferation significantly during the first days of culture, but it does not improve attachment and adhesion strength. Both materials do not differ with respect to protein synthesis or ultrastructural appearance of osteoblasts. Zirconium oxide may therefore be a suitable material for dental implants.

Strain-related bone remodeling in distraction osteogenesis of the mandible

Distraction osteogenesis has become a mainstay in craniofacial surgery. However, there are several unresolved problems concerning the biology of bone regeneration. We investigated the biomechanical effects of mandibular lengthening in 32 rabbits on a cellular and histologic level. The mandible was subjected to a corticotomy, held in a neutral position for 4 days, and then lengthened at various strain rates and frequencies for 10 days. Radiographic, histologic, and electron microscopic examinations showed a strain-related bone regeneration. Application of physiologic strain rates (2000 microstrains or 0.2 percent) led to a bridging of the artificial fracture exhibiting woven ossification, whereas at 20,000 microstrains trabecular bone formation was demonstrated. In contrast, hyperphysiologic strain magnitudes (200,000 microstrains and 300,000 microstrains) showed a fibrous tissue formation. Multiple strain applications (10 cycles/day versus 1 cycle/day) increased the width of the distraction gap without changing the stage of bone regeneration. The gradual distraction of bone in physiologic magnitudes at higher frequencies seems to be desirable for a bony differentiation and may help to improve clinical applications.

Current findings regarding zirconia implants

PURPOSE

The present article aims to analyze the available clinical data on the survival and success rate of dental zirconia implants (ZI).

MATERIAL AND METHOD

Studies (2006-2011) listed in the bibliography were obtained by using the key words "zirconia, zirconium, implants, dental, clinical" and combinations of these in different databases and on the internet. These articles served as a basis for the article.

RESULTS

A total of 17 clinical studies were found, involving 1,675 implants and 1,274 patients. In 16 studies, one-piece implant systems were investigated. The survival rates for ZI range from 74-98% after 12-56 months, with success rates between 79.6-91.6% 6-12 months after prosthetic restoration. However, the design of most of the studies show considerable shortcomings, and only low evidence level.

CONCLUSION

The small number of studies and the limited period of observation permit only a qualified statement on the clinical success of ZI. The results available to date indicate that ZI are inferior to titanium implants (TI) with regard to survival and success rates. Well-conducted long-term studies are urgently needed to permit a meaningful assessment of the survival or success rates of ZI and a statement concerning their application as an alternative to TI.

Effects of an occlusal splint compared with cognitive-behavioral treatment on sleep bruxism activity

The impact of an occlusal splint (OS) compared with cognitive-behavioral treatment (CBT) on the management of sleep bruxism (SB) has been poorly investigated. The aim of this study was to evaluate the efficacy of an OS with CBT in SB patients. Following a randomized assignment, the OS group consisted of 29, and the CBT group of 28, SB patients. The CBT comprised problem-solving, progressive muscle relaxation, nocturnal biofeedback, and training of recreation and enjoyment. The treatment took place over a period of 12 wk, and the OS group received an OS over the same time period. Both groups were examined pretreatment, post-treatment, and at 6 months of follow-up for SB activity, self-assessment of SB activity and associated symptoms, psychological impairment, and individual stress-coping strategies. The analyses demonstrated a significant reduction in SB activity, self-assessment of SB activity, and psychological impairment, as well as an increase of positive stress-coping strategies in both groups. However, the effects were small and no group-specific differences were seen in any dependent variable. This is an initial attempt to compare CBT and OS in SB patients, and the data collected substantiate the need for further controlled evaluations, using a three-group randomized design with repeated measures to verify treatment effects.

Osseointegration of zirconia implants: an SEM observation of the bone-implant interface

Background

The successful use of zirconia ceramics in orthopedic surgery led to a demand for dental zirconium-based implant systems. Because of its excellent biomechanical characteristics, biocompatibility, and bright tooth-like color, zirconia (zirconium dioxide, ZrO₂) has the potential to become a substitute for titanium as dental implant material. The present study aimed at investigating the osseointegration of zirconia implants with modified ablative surface at an ultrastructural level.

Methods

A total of 24 zirconia implants with modified ablative surfaces and 24 titanium implants all of similar shape and surface structure were inserted into the tibia of 12 Göttinger minipigs. Block biopsies were harvested 1 week, 4 weeks or 12 weeks (four animals each) after surgery. Scanning electron microscopy (SEM) analysis was performed at the bone implant interface.

Results

Remarkable bone attachment was already seen after 1 week which increased further to intimate bone contact after 4 weeks, observed on both zirconia and titanium implant surfaces. After 12 weeks, osseointegration without interposition of an interfacial layer was detected. At the ultrastructural level, there was no obvious difference between the osseointegration of zirconia implants with modified ablative surfaces and titanium implants with a similar surface topography.

Conclusion

The results of this study indicate similar osseointegration of zirconia and titanium implants at the ultrastructural level.

Evaluation of the quality of life of patients with maxillofacial defects after prosthodontic therapy with obturator prostheses

The purpose of this study was to investigate how patients with maxillofacial defects evaluate their quality of life after maxillectomy and prosthodontic therapy with obturator prostheses. 43 patients were included in the study (25 female, 18 male). 31 (72%) patients completed a standardized questionnaire of 143 items and then answered additional questions in a standardized interview. Global quality of life after prosthodontic therapy with obturator prostheses was 64% (±22.9) on average. Functioning of the obturator prosthesis, impairment of ingestion, speech and appearance, the extent of therapy, and the existence of pain had significant impact on the quality of life (p<0.005). Orofacial rehabilitation of patients with maxillofacial defects using obturator prostheses is an appropriate treatment modality. To improve the situation of patients prior to and after maxillectomy sufficient information about the treatment, adequate psychological care and speech therapy should be provided.

Irradiation induces increase of adhesion molecules and accumulation of beta2-integrin-expressing cells in humans

PURPOSE

The purpose of our investigation was to describe the dose- and time-dependent histomorphologic alterations of the irradiated tissue, the composition of the infiltrate, and the expression patterns of various adhesion molecules.

METHODS AND MATERIALS

We analyzed immunohistochemically alterations in oral mucosa in 13 head and neck cancer patients before radiotherapy and with 30 Gy and 60 Gy. All had oral mucosa irradiation, with a final dose of 60 Gy using conventional fractionation. Snap-frozen specimens were stained using the indirect immunperoxidase technique. Histomorphology was studied in paraffin-embedded sections. In addition, we determined the clinical degree of oral mucositis.

RESULTS

Histomorphologic evaluation showed no vascular damage. Irradiation caused a steep increase of beta2-integrin-bearing cells (p < 0.01), whereas the percentage of beta1-integrin-positive cells remained at low levels. Additionally we found an increase in the expression of endothelial intercellular adhesion molecule-1 (ICAM-1) (p < 0.01) and E-selectin (p < 0.05), while endothelial vascular cell adhesion molecule-1 (VCAM-1) expression remained at very low levels.

CONCLUSION

Our findings indicate that in radiation-induced oral mucositis there is no marked vascular damage until the end of radiotherapy. For recruitment of leukocytes, beta2 is more involved than beta1. Pharmaceuticals that block leukocyte adhesion to E-selectin or ICAM-1 may prevent radiation-mediated inflammation in oral mucosa.

Oral findings in three different groups of immunocompromised patients

The objective of this study was to determine the frequency of oral, dental and periodontal findings in three different groups of immunocompromised patients and in a healthy control group, to evaluate whether there is a correlation between manifestations of disease and immunologic parameters. The survey included 46 patients with a diagnosis of systemic lupus erythematosus, 48 heart transplant recipients, and 53 adult patients suffering from acute leukemias. Fifty matched healthy subjects were used as a control group. Each patient had to answer questions on medical and dental health and underwent a thorough oral, dental and serological investigation. Oral mucosal lesions were found in nearly half of all immunocompromised patients (49.6%), but in only 26% of control patients. No significant associations were found between different types of oral lesions and the underlying cause of immunosuppression. Leukemia patients showed age-unrelated higher scores in periodontal indices (P<0.05). Laboratory parameters failed to be significant in the assessment of oral health.

The new polyomavirus (MCPyV) does not affect the clinical course in MCCs

Since 2008, a new polyomavirus (MCPyV) in Merkel cell carcinomas (MCC) has been described, but little is known about its impact on the clinical course. The purpose of this study was to determine the presence of MCPyV in a large sample and to correlate the results with the clinical course of the disease. 59 samples from 44 patients were analysed for the presence of MCPyV using the primers LT3, VP1 and LT1. The clinical records of these patients were evaluated and correlated with the presence of MCPyV. 58% of specimens were positive for MCPyV. Of these, LT3 was positive in 53%, VP1 in 37% and LT1 in 10%. 57% of primary tumours and 53% of metastases were positive for LT3; the numbers for VP1 and LT1 were lower. There was no correlation between the detection of MCPyV in the primary tumour and the appearance of metastases. The survival time was statistically independent from the presence of MCPyV. There is a striking occurrence of MCPyV in MCC, but whether it affects the clinical course remains unclear.

Diagnostic accuracy of ultrasound, ¹⁸F-FDG-PET/CT, and fused ¹⁸F-FDG-PET-MR images with DWI for the detection of cervical lymph node metastases of HNSCC

OBJECTIVE

This study aimed to compare (18)F-fluorodesoxyglucose positron emission tomography/MRI ((18)F-FDG-PET-MRI) fusion images, including diffusion-weighted imaging (DWI), (18)F-FDG-PET/CT, and ultrasound (US) regarding their performance in nodal staging of patients with head and neck squamous cell carcinoma (HNSCC).

MATERIALS AND METHODS

Eighteen patients prospectively underwent ultrasound examination, (18)F-FDG- PET/CT, and MRI before oral tumor resection and bilateral neck dissection. PET data sets were fused with contrast-enhanced T1-weighted MR images. The sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), and accuracy for nodal detection were calculated for all the imaging modalities. Furthermore, the accuracy of the correct N-staging was calculated for all methods. Detailed histopathology served as the standard of reference.

RESULTS

The sensitivity, specificity, PPV, NPV, and accuracy for detection of lymph node metastases were 63, 99, 86, 96, and 95 % for ultrasound; 30, 97, 56, 92, and 90 % for (18)F-FDG-PET/CT; 52, 96, 59, 94, and 91 % for (18)F-FDG-PET-MRI; and 53, 97, 67, 95, and 92 % for (18)F-FDG-PET-MRI plus DWI, respectively. There was no significant difference in the diagnostic accuracy for lymph node metastasis detection between (18)F-FDG-PET-MRI and (18)F-FDG-PET/CT (p = 0.839) and between (18)F-FDG-PET-MRI plus DWI and (18)F-FDG-PET/CT (p = 0.286), respectively. US was significantly more accurate than (18)F-FDG-PET/CT (p = 0.009), whereas no significant difference was seen between (18)F-FDG-PET-MRI and US (p = 0.223) or (18)F-FDG-PET-MRI plus DWI and US (p = 0.115). The nodal stage was correctly rated by (18)F-FDG-PET-MRI in eight patients, (18)F-FDG-PET-MRI plus DWI in nine patients, US in 12 patients, and (18)F-FDG-PET/CT in five out of 18 patients.

CONCLUSION

Software-based fusion of (18)F-FDG-PET-MRI and (18)F-FDG-PET-MRI plus DWI may not increase nodal detection and N-staging performance in patients with oral malignancies compared to US and (18)F-FDG-PET/CT.

CLINICAL RELEVANCE

Surgical staging of cervical lymph nodes will not be replaced even by advanced imaging modalities in the near future.

Comparison of ectopic bone formation of embryonic stem cells and cord blood stem cells in vivo

Cell-based reconstruction therapies promise new therapeutic opportunities for bone regeneration. Unrestricted somatic stem cells (USSC) from cord blood and embryonic stem cells (ESCs) can be differentiated into osteogenic cells. The purpose of this in vivo study was to compare their ability to induce ectopic bone formation in vivo. Human USSCs and murine ESCs were cultured as both monolayer cultures and micromasses and seeded on insoluble collagenous bone matrix (ICBM). One week and 1, 2, and 3 months after implanting the constructs in immune-deficient rats, computed tomography scans were performed to detect any calcification. Subsequently, the implanted constructs were examined histologically. The radiological examination showed a steep increase in the mineralized bone-like tissue in the USSC groups. This increase can be considered as statistically significant compared to the basic value. Moreover, the volume and the calcium portion measured by computed tomography scans were about 10 times higher than in the ESC group. The volume of mineralization in the ESC group increased to a much smaller extent over the course of time, and the control group (ICBM without cells) showed almost no alterations during the study. The histological examinations parallel the radiological findings. Cord blood stem cells in combination with ICBM-induced ectopic bone formation in vivo are stronger than ESCs.

Desmoplastic fibroma of the mandible--review of the literature and presentation of a rare case

Desmoplastic fibroma (DF) is a rare, benign but locally aggressive, intraosseous lesion with a high tendency of local recurrence. In this report the actual literature is reviewed regarding epidemiological data, pathology, clinical diagnostic criterias, therapy and prognosis. Moreover, a report of an interesting case is included localized in the mandibular corpus.

Solitary submucous neurofibroma of the mandible: review of the literature and report of a rare case

Solitary neurofibroma is a rare benign non-odontogenic tumor. Particularly in the oral cavity, neurogenic tumors are rare, especially if they are malignant. Neurofibromas may present either as solitary lesions or as part of the generalised syndrome of neurofibromatosis or von Recklinghausen's disease of the skin. Clinically, oral neurofibromas usually appear as pediculated or sessile nodules, with slow growth and mostly without pain. The diagnosis can be confirmed by histological examination. Neurofibromas are immunopositive for the S-100 protein, indicating its neural origin. Treatment is surgical and the prognosis is excellent. For illustration a rare case of a solitary neurofibroma in the mandible is presented.

A survey on German dentists regarding the management of craniomandibular disorders

The purpose of the present investigation was to identify the most frequent therapies and, in particular, the prescription patterns for occlusal splints for the management of craniomandibular disorders (CMDs) used by German general dentists and specialists. Additionally, the knowledge and opinion of the practising dentists were examined. All active members of the statutory dental insurance providers of the German North Rhine (n = 5,500) and the Westphalia-Lippe area (n = 4,984) were surveyed with a questionnaire by mail. Results indicated that occlusal splints were the first-choice therapy followed by physiotherapy and occlusal equilibration. In the preceding year, both general dentists and specialists made 30 occlusal splints on average. With regard to high-quality evidence-based recommendations, some statistically significant discrepancies between general dentists and specialists were detected. On the basis of the present data, it seems useful to consider intensifying the topic of CMDs and orofacial pain in future undergraduate dental curricula and in postgraduate training.

Increase of RM3/1-positive macrophages in radiation-induced oral mucositis

The purpose of this study was to describe the distribution patterns of various leukocyte subpopulations in the oral mucosa during the course of radiotherapy and to determine whether there are dose-dependent alterations, or any correlation between the clinical stages and the population density of specific leukocytes. The distribution and density of various leukocytes in oral mucosa in 13 head and neck cancer patients were immunohistochemically analysed before radiotherapy at 30 and 60 Gy and compared with the clinical degree of oral mucositis. Antibodies were used which characterized different subtypes of macrophages (27E10, 25F9, RM3/1) and recognized epitopes of granulocytes (CD15) and T cells (CD3, CD4, CD8). The study showed that whereas macrophages reactive with RM3/1 increased significantly at 30 Gy (p<0.01) and showed a further increase at 60 Gy (p<0.01), no significant alterations could be detected in the density of macrophages which stained positively for 27E10 or 25F9. Moreover, the percentage of macrophages reactive with RM3/1 showed a non-linear correlation with the clinical mucositis score (p<0.05). No significant alterations were detected in the percentage of T cells and granulocytes, compared with the values before radiotherapy. In conclusion, radiation-induced mucositis is characterized by features of an intermediate stage of an inflammatory response, suggesting active involvement of down-regulatory macrophages in its pathogenesis.

Intraoral sebaceous carcinoma

Sebaceous carcinoma in the oral cavity is extremely rare, and we have found only four previously reported cases. We describe a fifth case. A wide surgical excision seems to be the correct treatment and estimation of serum carcinoembryonic antigen (CEA) may be a useful tumour marker in the follow-up of intraoral sebaceous carcinomas.

Orbital floor fractures--short- and intermediate-term complications depending on treatment procedures

Background

Many reconstruction materials for orbital floor fractures have been described in the past including autologous bone transplants, resorbable polymers and titan meshes. So far evidence is missing which material is used successfully regarding indication and particular size of defect. Therefore the aim of this study was to evaluate which reconstruction technique produces best clinical outcome and least complications associated with indication.

Methods

Retrospectively, surgical and ophthalmological data plus CT scans from a collective of 775 patients between 2005 and 2012 were analyzed. Furthermore included patients were sounded on satisfaction and potential problems postoperatively.

Results

Overall 593 patients offered full pre- and postoperative short-time data appropriate to inclusion criteria – of these 507 (85,5 %) underwent primary surgical treatment. Smallest average defect size was found in cases with no indication for surgical treatment (81 mm²), largest in cases indicating titanium mesh reconstruction (601.5 mm²). In 15 cases exact fragment reposition was possible without insertion of alloplastic material. Best clinical results obtained reconstruction using polydioxanone foil (PDS). 0.15 mm PDS-foil: 444 patients, reduced diplopia pre to postoperative 16 to 6 % (p < 0.01), ex- and enophthalmus < 2 % after surgery. 0.25 mm PDS-foil: 26 patients, reduced diplopia from pre- to postoperative 34,6 to 3,8 % (p < 0.01), postoperative exophthalmus rate was higher than preoperative (3,8 to 7,7 %). In comparison to reconstruction with PDS-foil a higher percentage of patients reconstructed with titanium meshes (n = 22) revealed no significant reduction of diplopia (45,5 to 31,8 %; p = 0.07). Furthermore 63 of all included patients agreed to complete a questionnaire on intermediate-term postoperative symptoms and surgical contentedness. Remarkably 50 % of the patients reconstructed with titanium meshes indicated foreign body sensations and cold feeling in the long-term.

Conclusions

Short- and intermediate-term results of clinical outcome in our patients with surgical treated orbital floor fractures (i.e. diplopia, en- or exophthalmus) reveal that thin resorbable foils, particularly 0.15 mm diameter PDS-foil seem to generate best results referring to orbital floor defects with a size of 250 to 300 mm².

Trial registration

Study number 4222, year 2013, ethics committee of the medical faculty of the Heinrich Heine university of Duesseldorf.

Principles of cartilage tissue engineering in TMJ reconstruction

Diseases and defects of the temporomandibular joint (TMJ), compromising the cartilaginous layer of the condyle, impose a significant treatment challenge. Different regeneration approaches, especially surgical interventions at the TMJ's cartilage surface, are established treatment methods in maxillofacial surgery but fail to induce a regeneration ad integrum. Cartilage tissue engineering, in contrast, is a newly introduced treatment option in cartilage reconstruction strategies aimed to heal cartilaginous defects. Because cartilage has a limited capacity for intrinsic repair, and even minor lesions or injuries may lead to progressive damage, biological oriented approaches have gained special interest in cartilage therapy. Cell based cartilage regeneration is suggested to improve cartilage repair or reconstruction therapies. Autologous cell implantation, for example, is the first step as a clinically used cell based regeneration option. More advanced or complex therapeutical options (extracorporeal cartilage engineering, genetic engineering, both under evaluation in pre-clinical investigations) have not reached the level of clinical trials but may be approached in the near future. In order to understand cartilage tissue engineering as a new treatment option, an overview of the biological, engineering, and clinical challenges as well as the inherent constraints of the different treatment modalities are given in this paper.

Vergleich der osteogenen Potenz gentechnisch modifizierter BMP

BACKGROUND

Modification of the heparin binding site by alteration of the amino acid sequence of bone morphogenetic protein-2 (BMP-2) results in a change in the local retention time. The purpose of this study was to compare the osteogenic activity of T3 and T4, two mutants with increased binding capacity to heparin, and B2GDF-5 a mutant resulting from the fusion of the n-terminal amino acid sequence of BMP-2 and the c-terminal sequence of GDF-5 with wild-type BMP-2 in vivo.

MATERIAL AND METHODS

The proteins were coupled to an equine-derived collagen carrier and implanted in standardized critical size calvarial defects in adult rats. After 28 days, bone formation was evaluated radiographically and the new bone was characterized histologically.

RESULTS

Proteins T3 and T4 showed a higher osteogenic activity than BMP-2. Less new bone formation was observed with GDF-5 and B2GDF-5 than with-type BMP-2. No difference in bone formation was observed between GDF-5 and B2GDF-5.

CONCLUSION

Increased heparin binding capacity enhances osteogenic activity of BMP-2 in vivo. This might be due to a longer retention period in the tissue and thus better bioavailability. Replacement of the N-terminal amino acid sequence of GDF-5 by the corresponding sequence of BMP-2 did not result in an increased osteogenic activity as heparin binding capacity is not the main reason for the bioavailability of GDF-5.