Site-Specific Variations in Bone Mineral Density under Systemic Conditions Inducing Osteoporosis in Minipigs

Osteoporosis is a systemic bone disease with an increasing prevalence in the elderly population. There is conflicting opinion about whether osteoporosis affects the alveolar bone of the jaws and whether it poses a risk to the osseointegration of dental implants. The aim of the present study was to evaluate the effects of systemic glucocorticoid administration on the jaw bone density of minipigs. Thirty-seven adult female minipigs were randomly divided into two groups. Quantitative computed tomography (QCT) was used to assess bone mineral density BMD of the lumbar spine as well as the mandible and maxilla, and blood was drawn. One group of minipigs initially received 1.0 mg prednisolone per kg body weight daily for 2 months. The dose was tapered to 0.5 mg per kg body weight per day thereafter. The animals in the other group served as controls and received placebo. QCT and blood analysis were repeated after 6 and 9 months. BMD was compared between the two groups by measuring Hounsfield units, and serum levels of several bone metabolic markers were also assessed. A decrease in BMD was observed in the jaws from baseline to 9 months. This was more pronounced in the prednisolone group. Statistically significant differences were reached for the mandible (p < 0.001) and the maxilla (p < 0.001). The administration of glucocorticoids reduced the BMD in the jaws of minipigs. The described model shows promise in the evaluation of osseointegration of dental implants in bone that is compromised by osteoporosis.

X-ray Microanalysis of Elements in the Masticatory Muscle after Paresis of the Right Masseter

Muscle activity and function appear to be related to ionic concentrations in the muscle. We investigated whether muscle paresis induced by injection of Botulinum toxin A (Botox) in 16-week-old pigs over a 56-day period is associated with ionic changes in the affected muscles. Tissue samples were taken from the masseter, temporalis, medial pterygoid, and geniohyoid muscles by a standardized method and used for energy-dispersive x-ray microanalysis in an environmental scanning electron microscope. The largest increase in Na+ was measured in the right and left sides of the masseter muscle in treated animals. Additionally, a significant elevation of Na+ was measured in the anterior part of the temporalis muscle and in the pterygoid muscle (P < 0.05). In temporalis and pterygoid muscles, an increase in sulfur in both sides of treated pigs’ heads was observed. Botox® has an indirect impact on ion concentrations, resulting in changes in muscle functional capacity and adaptive compensation of paretic muscle function by other muscles.

Multi-trajectories automatic planner for StereoElectroEncephaloGraphy (SEEG)

PURPOSE

StereoElectroEncephaloGraphy (SEEG) is done to identify the epileptogenic zone of the brain using several multi-lead electrodes whose positions in the brain are pre-operatively defined. Intracranial hemorrhages due to disruption of blood vessels can cause major complications of this procedure ([Formula: see text]1%). In order to increase the intervention safety, we developed and tested planning tools to assist neurosurgeons in choosing the best trajectory configuration.

METHODS

An automated planning method was developed that maximizes the distance of the electrode from the vessels and avoids the sulci as entry points. The angle of the guiding screws is optimized to reduce positioning error. The planner was quantitatively and qualitatively compared with manually computed trajectories on 26 electrodes planned for three patients undergoing SEEG by four neurosurgeons. Quantitative comparison was performed computing for each trajectory using (a) the Euclidean distance from the closest vessel and (b) the incidence angle.

RESULTS

Quantitative evaluation shows that automatic planned trajectories are safer in terms of distance from the closest vessel with respect to manually planned trajectories. Qualitative evaluation performed by four neurosurgeons showed that the automatically computed trajectories would have been preferred to manually computed ones in 30% of the cases and were judged good or acceptable in about 86% of the cases. A significant reduction in time required for planning was observed with the automated system (approximately 1/10).

CONCLUSION

The automatic SEEG electrode planner satisfied the essential clinical requirements, by providing safe trajectories in an efficient timeframe.

Coating with artificial matrices from collagen and sulfated hyaluronan influences the osseointegration of dental implants

Dental implants are an established therapy for oral rehabilitation. High success rates are achieved in healthy bone, however, these rates decrease in compromised host bone. Coating of dental implants with components of the extracellular matrix is a promising approach to enhance osseointegration in compromised peri-implant bone. Dental titanium implants were coated with an artificial extracellular matrix (aECM) consisting of collagen type I and either one of two regioselectively low sulfated hyaluronan (sHA) derivatives (coll/sHA1Δ6s and coll/sHA1) and compared to commercial pure titanium implants (control). After extraction of the premolar teeth, 36 implants were inserted into the maxilla of 6 miniature pigs (6 implants per maxilla). The healing periods were 4 and 8 weeks, respectively. After animal sacrifice, the samples were evaluated histomorphologically and histomorphometrically. All surface states led to a sufficient implant osseointegration after 4 and 8 weeks. Inflammatory or foreign body reactions could not be observed. After 4 weeks of healing, implants coated with coll/sHA1Δ6s showed the highest bone implant contact (BIC; coll/sHA1Δ6s: 45.4%; coll/sHA1: 42.2%; control: 42.3%). After 8 weeks, a decrease of BIC could be observed for coll/sHA1Δ6s and controls (coll/sHA1Δ6s: 37.3%; control: 31.7 %). For implants coated with coll/sHA1, the bone implant contact increased (coll/sHA1: 50.8%). Statistically significant differences could not be observed. Within the limits of the current study, aECM coatings containing low sHA increase peri-implant bone formation around dental implants in maxillary bone compared to controls in the early healing period.

Chondroitin sulfate and sulfated hyaluronan-containing collagen coatings of titanium implants influence peri-implant bone formation in a minipig model

An improved osseous integration of dental implants in patients with lower bone quality is of particular interest. The aim of this study was to evaluate the effect of artificial extracellular matrix implant coatings on early bone formation. The coatings contained collagen (coll) in conjunction with either chondroitin sulfate (CS) or sulfated hyaluronan (sHya). Thirty-six screw-type, grit-blasted, and acid-etched titanium implants were inserted in the mandible of 6 minipigs. Three surface states were tested: (1) uncoated control (2) coll/CS (3) coll/sHya. After healing periods of 4 and 8 weeks, bone implant contact (BIC), bone volume density (BVD) as well as osteoid related parameters were measured. After 4 weeks, control implants showed a BIC of 44% which was comparable to coll/CS coated implants (48%) and significantly higher compared to coll/sHya coatings (37%, p = 0.012). This difference leveled out after 8 weeks. No significant differences could be detected for BVD values after 4 weeks and all surfaces showed reduced BVD values after 8 weeks. However, at that time, BVD around both, coll/CS (30%, p = 0.029), and coll/sHya (32%, p = 0.015), coatings was significantly higher compared to controls (22%). The osteoid implant contact (OIC) showed no significant differences after 4 weeks. After 8 weeks OIC for controls was comparable to coll/CS, the latter being significantly higher compared to coll/sHya (0.9% vs. 0.4%, p = 0.012). There were no significant differences in osteoid volume density. In summary, implant surface coatings by the chosen organic components of the extracellular matrix showed a certain potential to influence osseointegration in vivo.

Vulvar melanoma and endometrial polyp following breast carcinoma: a case report

The authors describe the occurrence of a 55-year-old female patient presenting with a vulvar melanoma, endometrial polyp, and a prior history of breast carcinoma excised from the left chest wall, radiotherapy, chemotherapy, and tamoxifen maintenance for two years. This case exemplified second primary vulvar melanoma following breast cancer and supported that radiotherapy might play a role in the onset of secondary cancer. This case report also emphasizes the onset of endometrial polyp induced by tamoxifen.

Epileptic motor behaviors during sleep: anatomo-electro-clinical features

BACKGROUND

Sleep-related complex motor seizures have long been considered pathognomonic features of Nocturnal Frontal Lobe Epilepsy (NFLE). In recent years, these manifestations have also been reported to have a temporal or insular origin.

METHOD

We describe 40 drug-resistant epileptic patients with complex motor seizures during sleep, submitted to presurgical stereo-EEG (SEEG) evaluation and seizure-free after surgical resection of the epileptogenic zone.

RESULTS

In a significant proportion (30%) of these patients, seizures arose from extra-frontal regions, including mainly the temporal lobe and the insular cortex, but also the parietal and occipital lobes. In patients with extra-frontal epilepsy, when complex motor behaviors appeared, SEEG revealed that the ictal discharge involved the cingulate and the frontal regions. Finally, at histology, Taylor's focal cortical dysplasia (TFCD) was the most common finding (90% of patients), independent of the site of seizure onset.

CONCLUSION

As previously reported by other studies, this histologic substrate may be a major determinant of sleep-related seizures in drug-resistant epileptic patients.

Biological functionalization of dental implants with collagen and glycosaminoglycans-A comparative study

Biological implant surface coatings are an emerging technology to increase bone formation. Such an approach is of special interest in anatomical regions like the maxilla. In the present study, we hypothesized that the coating of titanium implants with components of the organic extracellular matrix increases bone formation and implant stability compared to an uncoated reference. The implants were coated using collagen-I with either two different concentrations of chondroitin sulfate (CS) or two differentially sulfated hyaluronans. Implant coatings were characterized biochemically and with atomic force microscopy. Histomorphometry was used to assess bone-implant contact (BIC) and bone-volume density (BVD) after 4 and 8 weeks of submerged healing in the maxilla of 20 minipigs. Further, implant stability was measured by resonance frequency analysis (RFA). Implants containing the lower CS concentration had significantly more BIC, compared to the uncoated reference at both times of interest. No significant increase was measured from week 4 to 8. Differences in BVD and RFA were statistically not significant. A higher concentration of CS and the application of sulfated hyaluronans showed no comparable increase in BIC. This study demonstrates a positive effect of a specific collagen-glycosaminoglycan combination on early bone formation in vivo.

Prefabricated bony radial forearm flap for secondary mandible reconstruction after radiochemotherapy

BACKGROUND

Primary reconstruction of the mandible is the golden standard of surgical treatment after ablative tumor surgery. Many different microvascular bone grafts are used to reduce wound healing complications at the severely compromised recipient site. The loss of primary grafts due to radiotherapy or osteoradionecrosis can make secondary mandibular reconstruction necessary. To address this problem, we developed the technique of the prefabrication of a radial forearm flap with cancellous bone. The aims were to establish these techniques into the clinical routine and to create a safe and reliable flap with low donor site morbidity.

METHODS

In patients who had undergone ablative tumor surgery radiochemotherapy, and primary reconstruction, prefabricated bony radial forearm flaps (PBRFFs) were applied for secondary reconstruction of the mandible. Cylinders of cancellous bone taken from the iliac crest were implanted in the lower forearm to allow the necessary vascularization. After a healing period of 4 weeks, the PBRFF was elevated and grafted into the mandibular defect.

RESULTS

All grafts healed uneventfully. However, 1 case required revision of the venous anastomosis after 2 days. The transplants improved the contour of the lower face enabling a good correction of the facial asymmetry. During the follow-up of up to 4 years, the radiographic controls showed good bony consolidation between the graft and the stumps of the mandible as well as formation of cortical bone around the cancellous bone cylinders.

CONCLUSION

These results demonstrate that the PBRFF is a safe and reliable graft which provides alternate solution in which other microvascular bone grafts have already failed. In the future, the iliac bone graft may be replaced with scaffold seeded with stem cells for further reduction of donor site morbidity.

Orthodontic tooth movement into jaw regions treated with synthetic bone substitute

INTRODUCTION

Orthodontic tooth movement is fraught with risks and complications. Root resorption is the most frequent and important outcome which may arise due to inappropriate force magnitude or tooth movement into dense or altered bone. This study was aimed to demonstrate histologic changes in tooth roots following movement into a jaw region treated with synthetic bone substitute. Another objective was to evaluate the method of experimental tooth movement using an animal model.

MATERIAL AND METHODS

One mandibular premolar was extracted in each of three pigs (Sus scrofa domesticus). The extraction alveolus was filled with synthetic bone substitute material and a orthodontic appliance was attached for 90 days. The force for tooth movement was in the range of 1-2 N. Subsequently, specimens were collected using segmental osteotomy and were prepared histologically. Unmoved teeth served as controls.

RESULTS

Histological analysis showed clear lacuna-like lesions in the root surface area of all specimens. The lesions were largest in the apical area, while the mid-root region was less affected.

CONCLUSIONS

Due to deformations of the orthodontic tooth moving appliance, the force could not be exactly defined. Therefore, marked resorption lesions of the root surfaces cannot be unequivocally attributed to the synthetic bone substitute. However, the type of lesions on root surfaces permits the assumption that orthodontic tooth movement into areas filled with synthetic bone substitute may be associated with an increased risk of root resorption.

Perfusion culture promotes differentiation of oral keratinocytes in vitro

In order to reconstruct the mucosal lining of the oral cavity tissue engineered autologous mucosa grafts could be of great benefit. In conventional stagnant cultures cells often tend to dedifferentiate. Perfusion culture has been demonstrated to reestablish differentiation in various epithelial cell types. Thus, in secondary cultures of human oral keratinocytes from ten patients conventional stagnant culture versus perfusion culture technique was compared. Proliferation and state of differentiation as expressed morphologically and immunohistochemically were assessed. After 14 days oral keratinocytes in a perfusion culture system tend to be further differentiated. They build up a thicker epithelium (3.4+/-1.0 vs. 2.4+/-0.4 layers), form microridges, express cytokeratins 1, 2, 10, 11, 19 but not 13 in all cells and cytokeratins 5, 6 particularly in cells attached to the carrier membrane. In contrast, oral keratinocytes in stagnant culture do not form microridges and rather express cytokeratins 13, 14, and 19 in mattering amounts.

Morphological evaluation of bone defect regeneration after treatment with two different forms of bone substitution materials on the basis of BONITmatrix

In the design of biomaterials for therapeutic application the evaluation of cellular/tissue responses play a key role. In this study, the in vivo bone-regenerative capacity and resorption of granular BONITmatrix and a paste-like bone substitution material on the basis of BONITmatrix were investigated in a rat cranial defect model. The results obtained with both biomaterials were compared to each other. For these, the paste-like composite and the granular BONITmatrix were implanted in adult male WOK-W rats, the skulls were harvested after eight weeks, and histopathological examinated. The comparison of the both tested biomaterials showed that the paste-like composite is much better to handle, the resorption of the material and the ossification process is much faster than those of granular BONITmatrix. The amount of newly formed bone was also measured and more bone formation was found in bone defects filled with the paste-like composite compared to those with granular BONITmatrix. The present study showed that both biomaterials could stimulate bone regeneration, but the paste-like composite leads in comparison to granular BONITmatrix to an accelerated more comprehensive bone regeneration.

Immunohistochemical comparison of differentiation markers on paraffin and plastic embedded human bone samples

To assess bone pathologies and bone regeneration immunohistochemistry may provide additional information compared to conventional histology. However, the effectiveness of this technique is limited due to tissue fixation, preparation and embedding. For bone tissue the standard immunohistological procedure includes formalin fixation, followed by decalcification and paraffin embedding. This may lead to a badly preserved trabecular bone structure but allows antibody application. Alternatively, methyl-methacrylate (MMA) resin may be used for embedding, thus circumventing the decalcification procedure. In this study immunohistology of typical bone markers was compared using human bone samples fixed either with alcohol or formalin and further decalcified and embedded in paraffin and decalcified or non decalcified samples embedded in Technovit 9100 New(R). On semi-thin sections immunohistochemistry with bone markers osteocalcin, osteonectin, osteopontin, collagen type I and the cellular markers CD34 and CD68 was performed. Independent of the fixative used, Technovit 9100 New embedded non-decalcified bone yielded a stronger immunostaining for all markers when compared to decalcified bone embedded either in methyl-methacrylate or paraffin. In addition there was a better preservation of the trabecular bone morphology. The immunohistochemical results demonstrate that Technovit 9100 New as a low-temperature acrylic resin embedding method can be favoured over paraffin embedding.

One-stage palate repair improves speech outcome and early maxillary growth in patients with cleft lip and palate

There are several types of palatal surgery; each cleft centre chooses its own technique based on experience and treatment philosophy. The aim of this study was to compare speech outcome and maxillary growth in children with cleft lip and palate deformity after palate repair with either a one-stage or a two- stage procedure and to identify the better treatment protocol. In 24 children, speech outcome was assessed regarding resonance, nasal escape, compensatory articulations, facial grimace, and spontaneous speech. In addition, plaster models of 15 children were compared. In 12 children, a two-stage procedure was performed (group A): at the age of 9-12 months, an intravelar veloplasty for repair of the soft palate, and at the age of 24-36 months a bipedicled flap closure of the hard palate. In 12 children, the same techniques were used in a one-stage procedure, at the age of 9-12 months (group B). The children of group B showed less altered resonance and less nasal emission at 4 years of age compared to the children of group A. At 6 years, the children of group A had improved their speech skills, but they did not equal the results of group B. In the study models of group A at age 6 years, the transverse dimension (anterior and posterior width of the dental arch) was smaller than in the models of group B. The one-stage repair of cleft palate at the age of 9-12 months seems to have a more positive influence on speech development and early maxillary growth than the two-stage procedure.

Changes in insulin like growth factors, myostatin and vascular endothelial growth factor in rat musculus latissimus dorsi by poly-3-hydroxybutyrate implants

The present study aimed at researching the synergistic effect between an ectopic bone substitute and surrounding muscle tissue. To describe this effect, changes of insulin like growth factors (IGF1, IGF2), myostatin (GDF8) and vascular endothelial growth factor (VEGF) mRNA content of 12 Wistar-King rats musculus latissimus dorsi with implanted poly-3-hydroxybutyrate (PHB) scaffold were examined after 6 and 12 weeks. At each time interval six rats were killed and implants and surrounding tissues prepared for genetic evaluation. Eight rats without any implants served as controls. RNA was extracted from homogenized muscle tissue and reverse transcribed. Changes in mRNA content were measured by Real-Time PCR using specific primers for IGF1, IGF2, GDF8 and VEGF. Comparing the level of VEGF mRNA in muscle after 6 and 12 weeks to the controls, we could assess a significant increase of VEGF gene expression (p<0.05) whereas the level of mRNA expression was higher after 6 than after 12 weeks of treatment. Expression of IGF1 gene was also significantly increased as compared to the controls over the observed period of time (p<0.05). In the case of the IGF2 gene, the expression was significantly elevated after 6 weeks (p<0.05), but not significantly increased after 12 weeks (p>0.05). We observed a significantly decreased GDF8 gene expression (p<0.05) both after retrieval of implants after 6 as well as after 12 weeks. Moreover, mRNA level of GDF8 after 6 and 12 weeks were comparable the same. Our results show that PHB implants in rat musculus latissimus dorsi interact with the surrounding muscle tissue. This interaction works itself on growth potential of the muscle.

Surface-conditioned dental implants: an animal study on bone formation

AIM

The aim of this study was to determine whether bone formation around surface-conditioned implants is enhanced compared with non-surface-conditioned sandblasted acid-etched titanium implants.

MATERIALS AND METHODS

One hundred and forty-four implants were placed in the mandible of 18 minipigs. Before placement, implants were either surface conditioned in a solution containing hydroxide ions (conSF) or assigned to controls. Animals were euthanized after 2, 4 and 8 weeks of submerged healing, the 8-week group receiving polyfluorochrome labelling at week 2, 4, 6 and 8. One jaw quadrant per animal was selected for histological and histomorphometrical evaluation of mineralized bone-implant contact (mBIC), osteoid-implant contact (OIC) and bone volume (BV) analysis.

RESULTS

Polyfluorochrome labelling showed no general differences in bone dynamics. mBIC showed the most pronounced differences after 2 weeks, reaching 65.5% for conSF compared with 48.1% for controls, p=0.270. Differences levelled out after 4 weeks (67.4% control, 65.7% conSF) and 8 weeks (64.0% control, 70.2% conSF). OIC levels were initially comparable, showing a slower decline for conSF after 4 weeks. BV was higher for conSF at all times. No significant differences could be found.

CONCLUSION

A tendency towards increased mBIC was shown for surface-conditioned implants after short-term healing.

Mechanical loading of orthodontic miniscrews - significance and problems: an experimental study

Orthodontic miniscrews are exposed to three mechanical loading phases during clinical use: torsional loading upon insertion, flexural loading during anchorage function, and torsional loading upon removal. The aim of this study was to simulate clinical loading conditions for different types of orthodontic miniscrews in vitro to quantify the effects of combined torsional and bending stress. Various orthodontic miniscrew systems (Lomas, Dual-top, Aarhus anchorage, Tomas-pin and T.I.T.A.N.-pin) comprising 10 samples each were subjected to the following loading sequences in vitro: a torsional load corresponding to manual insertion with limited torque; and flexural loading at two different insertion depths. For all screw systems with torsional pre-loading (simulating insertion), subsequent flexural loading (simulating anchorage) yielded permanent deformations of approximately 0.15-0.25 mm, depending on the insertion depth. Since EDX analysis revealed comparable elemental compositions for the different screw systems, the differences in mechanical properties are attributed to screw design. Torsional loading during screw insertion may cause premature mechanical weakening and needs to be minimized. Unless fully inserted, screws show pronounced plastic deformation and hence fracture risk under subsequent flexural loading.

Epilepsy surgery in tuberous sclerosis complex: early predictive elements and outcome

AIM

The aim of the study was to evaluate the surgical treatment of epilepsy and detection of possible early surgery predictive elements in patients with tuberous sclerosis complex (TSC).

MATERIALS AND METHODS

Forty-two TSC patients with epilepsy were selected and divided into two main groups: definite and fruste forms. Definite forms were divided into different groups: patients with pharmacologically controlled epilepsy, patients with pharmacoresistant epilepsy excluded from surgery after an extensive presurgical assessment, and patients with a pharmacoresistant epilepsy who underwent surgery. We compared the definite TSC groups to identify elements that predict surgical candidacy. Second, we compared all operated patients to assess surgical outcome.

CONCLUSION

We found several factors that could predict a surgical intervention even if identification of patients with refractory epilepsy who can benefit from surgery is an evolving process. Also, several positive factors for good surgical outcome were identified. Patients with the fruste form had excellent surgical outcome.

Free DIEP-flap reconstruction of tumour related defects in head and neck

The free deep inferior epigastric perforator flap (DIEP) is a well-established therapy for plastic reconstruction of the breast or defects of the lower extremity without distinct donor site morbidity. Because of its particular qualities we started to apply the DIEP-flap also in reconstruction of defects in the cranio-maxillofacial area. A series of 10 consecutive patients, who received a DIEP-flap for reconstruction of large soft tissue defects after ablative tumour surgery, was reviewed. Nine of the 10 flaps survived and uneventfully healing was observed in 8 of the 10 flaps. Primary layered closure of the abdominal wall was achieved in all cases and no complications at the donor site were observed. In our experience the DIEP may serve as a well considerable alternative to the rectus abdominis flap and the latissimus dorsi flap for bridging extensive reconstructions in the cranio-maxillofacial region. It offers the possibility for flap elevation simultaneously to the surgical procedures in the head and neck area. A special advantage of the DIEP-flap is the very low donor site morbidity.

Soft tissue integration in the neck area of titanium implants--an animal trial

Dental implant materials are required to enable good apposition of bone and soft tissues. They must show sufficient resistance to chemical, physical and biological stress in the oral cavity to achieve good long-term outcomes. A critical issue is the apposition of the soft tissues, as they have provided a quasi-physiological closure of oral cavity. The present experiment was performed to study the peri-implant tissue response to non-submerged (1-stage) implant installation procedures. Two different implants types (NobelBiocare, NobelReplace Tapered Groovy 4.3 x 10 mm and Replace Select Tapered TiU RP 4.3 x 10mm) were inserted into the right and left sides of 8 domestic pigs (Sus scrofa domestica) mandibles, between canines and premolars and immediately provided with a ceramic crown. Primary implant stability was determined using ressonance frequency analysis. Soft tissue parameters were assessed: sulcus depth (SDI) and junctional epithelium (JE). Following 70 days of healing, jaw sections were processed for histology and histomorphometric examination. Undecalcified histological sections demonstrated osseointegration with direct bone contact. The soft tissue parameters revealed no significant differences between the two implant types. The peri-implant soft tissues appear to behave similarly in both implant types.

Adaptation of myosin heavy chain mRNA expression after implantation of poly(3)hydroxybutyrate scaffolds in rat m. latissimus dorsi

The aim of this study is to identify the synergistic effect between an ectopic bone substitute and surrounding tissues, in this case muscle tissue, which is known to have a considerable potential for adaptation. To describe this effect, changes of myosin heavy chain (MyHC) isoform mRNA content of 12 Wistar-King rats m. latissimus dorsi with implanted poly(3)hydroxybutyrate (PHB) scaffolds were examined after six and 12 weeks. At each time interval six rats were killed and implants and surrounding tissues prepared for genetic evaluation. Eight rats without any implants served as controls. After homogenisation of muscle tissue, RNA was extracted and reverse transcribed. Changes in mRNA content were measured by Real-Time PCR using specific primers for type I MyHC, IIa, IIb and IIx isoforms. The mRNA level of myosin isoform type I of the muscles surrounding the implant was significantly increased (p<0.02) compared to the control group. Further, the studied muscle tissue showed a significant decrease in MyHC isoform IIx mRNA compared to the controls (p<0.02). Implantation of PHB scaffolds into rat m. latissimus dorsi causes an increase of its' content of slow myosin isoforms indicating a synergistic effect between the PHB scaffold and the surrounding muscle tissue.

Cell passage and composition of culture medium effects proliferation and differentiation of human osteoblast-like cells from facial bone

Cells loose their capability to multiply and to differentiate when they are serial subcultivated. However, both, multiplication and differentiation are of utmost importance to obtain sufficient amounts of cells for the translation of tissue regeneration into cell based therapeutic approaches. Thus, for the clinical application more information about ideal culture conditions are necessary. Therefore, aim of this study was to assess culture conditions of human osteoblast-like cells during long-term culture focusing on effects of different culture media and ascorbic acid. Biopsies of maxilla and mandible were obtained from 17 patients to test different cell culture media and from 10 patients to analyse differentiation and proliferation related to number of subcultures and ascorbic acid content. Histochemical and immunhistochemical tests (EZ4U assay, ALP histochemistry, type I collagen immunohistochemistry, osteocalcin Elisa) were performed to determine cell proliferation and differentiation. Opti-MEM with 10% FCS produced statistically significant the highest increase in cell counts. The highest proliferation rate in long-term cultivation was seen in the 4th cell passage. A reciprocal relationship between cell proliferation and differentiation over 5 passages with a turning point in the 4(th) passage was found. An ascorbic acid content of 50 microg/ml triggered an optimal increase in differentiation. For osteoblast-like cells, Opti-MEM with 10% FCS proved to be the best culture medium. After 3 passages there is the highest amount of cells with osteogenic differentiation which is enhanced by the addition of ascorbic acid. This approach is suitable for tissue engineering of bone grafts.

Investigations about N-aminopropyl transferases probably involved in biomineralization

Polyamines are widespread distributed all over in living organisms. In Thalassiosira pseudonana 10 N-aminopropyl transferase like nucleotide sequences exists. It is assumed that these sequences are involved in the biomineralization of the diatom shell. The cDNA of the sequences were cloned, recombinant overexpressed and assayed with decarboxylated S-adenosylmethionine and several radioactive labelled polyamines. However, only a spermidine synthase and a thermospermine synthase were found to be enzymatically active in an in vitro assay. Both enzyme activities could be recognized in the crude extracts of Thalassiosira pseudonana and Cyclotella meneghiana. In further investigations the kinetics of the thermospermine synthase was determined and a site-specific mutagenesis of the bindig cavity of decarboxylated S-adenosylmethionine was carried out.

Evaluation of shape and size changes of bone and remodelled bone substitute after different fixation methods

Suitable tissue fixation is indispensable to histological analysis. This investigation, therefore, sought to evaluate changes of shape and size of bone specimens and remodelled bone substitute material following different fixation methods. Mandibular bones of 9 pigs (Sus scrofa domesticus) served as specimens. Two mandibular premolars were extracted respectively and the extraction alveoli were filled with synthetic bone substitute material. The samples were collected after 70 days. Fixation of 6 specimens respectively was done for 7 days in 4% formalin (formaldehyde), 70% ethanol and glycerol at 18 degrees C room temperature. The samples were radiographically examined before and after fixation using a reference specimen and subsequently underwent histological analysis. After fixation in formalin, the samples showed no size changes. After fixation in glycerol, morphological analysis revealed minor shape changes. Fixation in ethanol causes shrinking of the tissue specimens. Histological inspection of the tissues shows no morphological changes except slight shrinking. In conclusion there is no universal fixative that could met all requirements and permited proper examination without affecting tissues or bone specimens.

Immunohistochemical comparison of markers for wound healing on plastic-embedded and frozen mucosal tissue

Immunohistologic investigations of wound healing in human oral mucosa require specific cell biological markers as well as consecutive small biopsies. Small specimens are ideally embedded in plastic (methylmethacrylate, MMA) resin due to their miniature size. This limits the use of antibodies for these markers. In this immunohistochemical study, the distribution of wound healing markers, e.g. cytokeratin (CK), laminin, collagen IV, vimentin, vinculin and fibronectin, were compared between semithin sections of plastic-embedded tissue and frozen sections of mucosal tissue in order to assess their use for future investigations. The antibodies against laminin, collagen IV and CK 1/2/10/11, 5/6, 13, 14, 17, 19 gave comparable staining patterns on cryostat sections of attached mucosa and on semithin sections of MMA-embedded attached mucosa. In the epithelial cell layers, the following distribution of CK immunostaining was observed: The basal cell layer was positive for CK 5/6, CK 14 and CK 19; the intermediate cell layer for CK 13, CK 17 and CK 1/2/10/11, and the superficial cell layer for CK 13 and CK 1/2/10/11. For most of these antibodies, enzyme digestion with 0.1% trypsin was adequate for demasking the antigens, except for anti-CK 14, anti-CK 17 and anti-laminin; predigestion with 0.4% pepsin in 0.01 N HCl gave similar staining results. The antibodies against vimentin, vinculin, fibronectin and CK 4 showed no affinity or a reciprocal reaction on the semithin sections. Therefore, the antibodies against CK 1/2/10/11; 5/6; 13; 14; 17, and 19, as well as the basement proteins laminin and collagen IV are deemed markers suitable on semithin sections of plastic-embedded attached oral mucosa.

Effect of biological implant surface coatings on bone formation, applying collagen, proteoglycans, glycosaminoglycans and growth factors

OBJECTIVES

The aim of the present study was to evaluate six different implant surface coatings with respect to bone formation. Being major structural components of the extracellular matrix, collagen, the non-collagenous components decorin/chondroitin sulphate (CS) and the growth factors TGF-beta1/BMP-4 served in different combinations as coatings of experimental titanium implants.

MATERIALS AND METHODS

Eight miniature pigs received each six implants in the mandible. The implant design showed two circular recesses along the length axis. Three, four, five and six weeks after implant placement, the animals were sacrificed in groups of two. Bone-implant contact (BIC) was evaluated along the outer implant surface and within the recesses. Bone volume was determined by synchrotron radiation micro computed tomography (SRmicroCT) for one implant of each surface state, 6 weeks after placement.

RESULTS

At each week of observation, collagen/CS or collagen/CS/BMP-4 coated implants showed the highest BIC of all surface states. This was statistically significant at week five (p=0.030, p=0.040) and six (p=0.025, p=0.005). SRmicroCT measurements determined the highest bone volume for a collagen/CS coated implant.

CONCLUSION

The results indicate that collagen/CS and collagen/CS/BMP-4 lead to a higher degree of bone formation compared to other ECM components.

Effect of bone conditioning on primary stability of FRIALIT-2 implants

BACKGROUND

Primary stability is crucial to implants used for orthodontic anchorage. Bone condensing to enhance primary stability is controversial.

MATERIAL AND METHODS

Fourteen Frialit-2-stepped screw and cylinder implants were placed in the median palatine sutures of 22 cadaveric human heads. In half of both types, the implant bed was prepared using a Frialit Bone Condenser. Primary implant stability was evaluated using non-invasive resonance frequency analysis. Moreover, the bone-implant contact area was examined histomorphometrically and radiographically.

RESULTS

Bone condensing yielded a slightly, yet not significantly increased implant stability quotient compared with a conventional technique. In spongy bone, a significant histomorphometric increase of bone-implant contact (P<0.0001) and a significant increase of radiographic density was revealed for both implant types, while no significant changes were observed within the compact area.

CONCLUSION

The study shows that bone condensing yields an improved histologic implant-bone contact only in spongy bone, which was paralleled by radiographic-densitometric findings.