Fronto-orbito-nasal advancement a surgical approach based on skull development in treatment of craniofacial deformities.

The classical treatment of craniosynostosis is based on the fundamental work by Tessier. However, developmental aspects suggest modified osteotomy lines like fronto orbito nasal advancement combined with a modified midfacial distraction. This also makes it possible to take assess the different distances of the anterior displacement of the individual parts of the skull. Pioneering in therapy is less the syndrome itself than the accompanying symptoms such as respiration and intracranial pressure. For brain release we recommended (Joos 1998) the osteoclastic procedure according to Powiertowsky (1974) within the first 6 months of life. For further treatment frontoorbito-nasal advancement and modified midface distraction seem to achieve better results in enlarging the inner nose and a more harmonious profile.

Blended learning in postgraduate oral medical and surgical training - An overall concept and way forward for teaching in LMICs.

E-learning programmes have become established in postgraduate oral medical education and training. Internet and literature researches show a variety of good concepts that provide an attractive alternative to face-to-face training. What is missing is an overall concept in which continuing education and training are offered in bundled form in various teaching and learning formats. We discuss the blended learning concept which offers the best options, which has been proven by scientific studies. Using the example of the International Medical College (IMC) at the University of Duisburg-Essen, a blended learning overall concept for postgraduate continuing education is presented.

Reconstruction of large defects on the scalp and forehead as an interdisciplinary challenge: experience in the management of 39 cases.

AIMS: To describe options and indications for different surgical reconstruction techniques after resection of large skin tumours on the scalp taking into account an interdisciplinary approach of cranio-maxillofacial surgeon, dermatologist, and neurosurgeon, and to evaluate complications and postoperative outcome. PATIENTS AND METHODS: From a total of 39 patients with large skin tumour resections on the scalp and/or the forehead, treated between January 01, 1995 and June 30, 2005, a number of 42 surgical reconstructions were performed. The medical histories, the surgical treatment, postoperative complications, follow-up and outcome were evaluated. RESULTS: The excision defects measured 146 cm(2) (range: 80.6-546 cm(2)) on average. The most common methods for defect closure were multiple rotation-advancement flaps (n=19). Six patients were treated with split-thickness skin grafts after bone drilling for inducing granulation tissue to grow. Free latissimus dorsi muscle flaps were used in 8 patients and radial forearm flaps in 4 cases. Postoperative complications were rare. An algorithm for the surgical approach to large scalp defects was developed. CONCLUSION: For reconstruction of large defects on the scalp and forehead, various reliable methods may be used with regard to individual patient-specific parameters in cooperation with different medical specialties involved.

Technical and clinical assessment of the use of a new material-based splint in orthognathic surgery.

Heat or auto-cured acrylic resins are materials that are commonly used in splint construction. Newly developed light-cured resins hold promise in view of the altered characteristics of the material. The aim of this study was to evaluate how far light-curing resin-based splints can be used in orthognathic surgery. Over a period of 1 year, 141 orthognathic surgeries were planned and performed using randomly chosen light-cured splints versus auto-polymerized splints. The performance of splint fabrication, the model planning and the clinical use were assessed by different measurements. The dental technician, the orthodontist and the surgeon evaluated objective parameters (model damage, fabrication time, accuracy of registration, adjustment time) as well as subjective criteria (handling). This study revealed that the use of light-curing splints significantly improved the accuracy (97.7% versus 81.2% in the case of acrylic materials). Less time was needed for the fabrication and adjustment of the splint. There was concomitantly less model damage to be observed when light-curing resins were used (9.2% versus 83.5%) and subjective measurements revealed significantly better handling of light-curing resin-based splints. Light-curing resin splints used in orthognathic surgery seem to be advantageous.

Mineralization at the interface of implants.

Osseointegration of implants is crucial for the long-term success of oral implants. Mineralization of the bone's extracellular matrix as the ultimate step of a mature bone formation is closely related to implant osseointegration. Osteogenesis at oral implants is a complex process, driven by cellular and acellular phenomena. The biological process of the maintenance and emergence of minerals in the vicinity of oral implants is influenced to a great extent by biophysical parameters. Implant-related structural and functional factors, as well as patient-specific factors, govern the features of osteogenesis. To understand the influence of these factors in peri-implant bone mineralization, it is important to consider the basic biological processes. Biological and crystallographic investigations have to be applied to evaluate mineralization at implant surfaces at the different hierarchical levels of analysis. This review gives insight into the complex theme of mineral formation around implants. Special focus is given to new developments in implant design and loading protocols aimed at accelerating osseointegration of dental implants.

Electrical stimulation influences mineral formation of osteoblast-like cells in vitro.

The aim of the present study was to assess the structure of newly formed mineral crystals after electrical stimulation of osteoblast-like cells in vitro. Pulsed electrical stimulation was coupled capacitively or semi-capacitively to primary osteoblast-like cells derived from bovine metacarpals. Computer calculations revealed that the chosen input signal (saw-tooth, 100 V, 63 ms width, 16 Hz repetition rate) generated a short pulsed voltage drop of 100 microV (capacitive coupled mode) and of 350 microV (semi-capacitive coupled mode) across the cell-matrix layer. Stimulated cultures showed an enhanced mineral formation compared to the non stimulated controls. In cultures exposed to capacitively coupled electric fields and in control cultures nodules and mineralized globules were found. Nodules with a diameter of less than 200 nm covered the cell surface, whereas mineral globules with a diameter of up to 700 nm formed characteristic mineral deposits in the vicinity of the cells similar to biomineral formations occurring in mineralizing tissues. In contrast, large rod-shaped crystals were found in cultures stimulated by semi-capacitive coupled electric fields, indicating a non-physiological precipitation process. In conclusion, osteoblasts in culture are sensitive to electrical stimulation resulting in an enhancement of the biomineralization process.

Basic reactions of osteoblasts on structured material surfaces.

In order to assess how bone substitute materials determine bone formation in vivo it is useful to understand the mechanisms of the material surface/tissue interaction on a cellular level. Artificial materials are used in two applications, as biomaterials alone or as a scaffold for osteoblasts in a tissue engineering approach. Recently, many efforts have been undertaken to improve bone regeneration by the use of structured material surfaces. In vitro studies of bone cell responses to artificial materials are the basic tool to determine these interactions. Surface properties of materials surfaces as well as biophysical constraints at the biomaterial surface are of major importance since these features will direct the cell responses. Studies on osteoblastlike cell reactivity towards materials will have to focus on the different steps of protein and cell reactions towards defined surface properties. The introduction of new techniques allows nowadays the fabrication of materials with ordered surface structures. This paper gives a review of present knowledge on the various stages of osteoblast reactions on material surfaces, focused on basic cell events under in vitro conditions. Special emphasis is given to cellular reactions towards ordered nano-sized topographies.

Magnesium in newly formed dentin mineral of rat incisor.

Small amounts of magnesium are always detectable in addition to calcium and phosphorus in mineralized tissues such as dentin or bone. Magnesium has been considered to influence the mineralization process, especially crystal growth. The present study reports on the location and enrichment of magnesium in the newly mineralized dentin by using the high lateral resolution of energy dispersive X-ray microanalysis combined with scanning transmission electron microscopy. To this end, we have used the continuously growing rat incisor as a model for a collagenous mineralizing system. Dental tissue was dissected free and cryofixed in liquid nitrogen-cooled propane. The distribution of elements was measured in freeze-dried ultrathin cryosections. The magnesium distribution of the newly formed dentin area near the predentin area was found to be inhomogeneous. In certain small dentin areas, characteristical magnesium enrichments were observed. Further, high magnesium-to-phosphate molar ratios were found in these areas, and these were correlated with low calcium-to-phosphate molar ratios. Our results support the theory that magnesium is involved in the process of biological apatite crystal formation.

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.

Preliminary studies on the phenomenological behaviour of osteoblasts cultured on hydroxyapatite ceramics.

SEM was used to investigate the phenomenological behaviour of osteoblasts towards sintered hydroxyapatite. The osteoblasts were seeded on to porous and dense hydroxyapatite and cultured for 4 to 28 d. They attached and adhered on to the hydroxyapatite surfaces, proliferated and secreted extracellular matrix. No signs of toxicity embarrassment were apparent. It is argued that cell phenomenology seems to be a prerequisite to morphogenesis, and on this premise it is speculated that surface-reactive bone replacement materials owe their compatibility to the ability of their surfaces to interact favourably with the peptides involved in osteomorphogenesis and bone repair.

Influence of Collagenfleece on bone regeneration.

It can be demonstrated that bone regeneration is stimulated by implantation of Collagenfleece a purified, heterologous collagen preparation. Defects were created in rabbit mandibles which were filled with Collagenfleece on the right side, while the defect on the left side served as a control. The progress in bone regeneration was followed by comparative light and electron microscopic investigations. In contrast to the controls, the defects which were treated with Collagenfleece showed quicker ossification.

Ultrastructural characterization of the implant/bone interface of immediately loaded dental implants.

Primary stability and an optimized load transfer are assumed to account for an undisturbed osseointegration process of implants. Immediate loaded newly designed titanium dental implants inserted in the mandible of minipigs were used for the characterization of the interfacial area between the implant surface and the surrounding bone tissue during the early healing phase. Histological and electron microscopical studies were performed from implant containing bone specimens. Two different load regimens were applied to investigate the load related tissue reaction. Histological and electron microscopical analysis revealed a direct bone apposition on the implant surfaces, as well as the attachment of cells and matrix proteins in the early loading phase. A striking finding of the ultrastructural immunocytochemical investigations was the synthesis and deposition of bone related proteins (osteonectin, fibronectin, fibronectin receptor) by osteoblasts from day one of bone/biomaterial interaction. Calcium-phosphate needle-like crystallites were newly synthesized in a time-related manner directly at the titanium surface. No difference in the ultrastructural appearance of the interface was found between the two loading groups. Our experimental data suggest that loading of specially designed implants can be performed immediately after insertion without disturbing the biological osseointegration process.

In situ assessment of cell proliferation at the invasive front of oral squamous cell carcinomas.

In oral squamous cell carcinoma (OSCC) the histopathological malignancy grading of the invasive front has been found to offer the most reliable prognostic parameter. In the present study we compared such tumour front grading of 100 OSCCs with the in situ growth fraction demonstrated by MIB1 immunostaining following wet autoclave antigen retrieval. MIB1 labelling indices (LIs) were estimated both at the invasive front and in the central parts of OSCCs using two different evaluation methods (overall and random counting) to investigate whether MIB1 LIs represent a possible biological background for the tumour front grading. Statistically highly significantly increased MIB1 LIs were found at the invasive tumour fronts with both counting methods compared with the centres of the same tumours. For LI estimation the classic overall counting procedure proved to be superior. However, in contrast to tumour front grading, MIB1 LIs revealed no correlation with the clinical outcome of the patients concerned. Our results demonstrate that the invasive tumour front of an OSCC is composed of (a) tumour subpopulation(s) with higher proliferative activity. However, determination of the proliferative activity by MIB1 of this tumour area offers no prognostic information.

Clinical relevance of erbB-1 and -2 oncogenes in oral carcinomas.

To gain a better understanding of molecular changes in oral squamous cell carcinomas, we tested fresh tumour specimens from 110 patients for erbB-1 and -2 oncogene aberrations using the competitive differential polymerase chain reaction. The significance of established tumour characteristics such as TNM stage, differentiation and oncogene aberrations for tumour progression were analyzed. ErbB-2 amplification with a gene copy number > 1.6 in tumour tissue and erbB-1 deletion with a gene copy number < 0.4 in tumour-surrounding mucosa are of clinical relevance and indicate an early tumour recurrence or metastasis (p < 0.05). In T1/T2 tumours an erbB-2 gene dosage study allows differentiation between tumours with high or low risk for early progression. In a multivariate statistical analysis T stage (p < 0.01) and erbB-2 amplification in tumour material (p < 0.05) were independent prognostic variables.

The erbB oncogenes as prognostic markers in oral squamous cell carcinomas.

BACKGROUND: In clinical practice it became clear that conventional prognostic parameters of oral squamous cell carcinomas (OSCC) are of limited value for the prediction of a disease-free survival. The overexpression of erbB oncogenes is of importance for the clinical course of a variety of solid tumors. After discovering amplifications of erbB oncogenes even in OSCC, it was the aim of the present study to clarify the potential of oncogenes as additional prognostic markers. MATERIALS AND METHODS: The amplification of the erbB oncogenes in tumorous tissue of 85 OSCC patients was determined using the double-differential polymerase chain reaction. Histologically healthy mucosa in these patients was also studied. In univariate analysis the amplification of erbB oncogenes with clinical and histopathological prognostic parameters was compared. RESULTS: No significant correlation between common prognostic parameters and erbB-2 amplification was found. Patients whose OSCC tissue showed an average gene copy number for erbB-2 of greater than 1.2, for erbB-3 below 0.11, and a ratio of erbB-1 and erbB-2 below 0.31 had a statistically significant decrease in disease-free survival. Even in histologically healthy oral mucosa from tumor patients an amplification of erbB oncogenes was found. CONCLUSIONS: ErbB oncogene amplifications in oral squamous cell carcinomas play a significant role as a prognostic factor and seem to be effective in predicting decrease in disease-free survival. Genetic abnormalities in tumor-surrounding tissue support the field cancerization hypothesis.

Interaction of osteogenic cells with hydroxylapatite implant materials in vitro and in vivo.

In a series of scanning electron microscopic studies, the reaction of osteogenic cells to hydroxylapatite (HA) implant materials was investigated in culture and following implantation. Tissue components as found in normal rat and dog bone were identified at the interface in both test systems. In vivo, implant bed cells showed an intimate contact with the HA surfaces. Osteoblasts deposited organic matrix and bone mineral in direct apposition to HA, with no evidence of encapsulation or granulation tissue. The development of such a direct spatial relationship appears to involve mechanisms more encompassing than epitaxis.

Restoration of maxillary residual ridge atrophy using Le Fort I osteotomy with simultaneous endosseous implant placement: technical report.

When residual ridge atrophy of the edentulous mandible and maxilla is accompanied by a skeletal Class III jaw relationship, surgical correction is necessary for optimal functional, phonetic, and esthetic results whenever implant-supported prostheses are to be placed. A method is described in which a single procedure combines the endosseous placement of nonsubmerged titanium implants in appropriate prosthetically predetermined locations with defined advancement of the maxilla. Preoperative diagnostic examinations, cast simulation, and transfer of the latter to the site of surgery are of the utmost importance.

Evaluation of the result of surgery on cleft lip and palate and skeletal growth determinants of the cranial base.

In evaluating the results of surgery on cleft lip and palate, the growth determinants have to be taken into consideration. The goal should be that the dentoalveolar conditions coincide with the growth tendencies at the base of the skull upon termination of growth. If there is a tendency at the cranial base to class III, most likely it will not be possible to achieve a dentoalveolar angle class I without osteotomies.

Muscle reconstruction in primary cleft lip surgery.

Skeletal maldevelopment in the mid-face in the case of cleft lip and palate is caused by an inadequate surgical reconstruction of the paranasal muscles. This results in deficient functional stimulus to the desmal osteogenesis at the mid-face sutures. Early reconstruction of these muscles can prevent secondary skeletal maldevelopment.

Reconstruction of the severely resorbed (Class VI) jaws: routine or exception?

After disappointing results with conventional preprosthetic procedures endosseous implants in combination with alveolar ridge augmentation opened up new prospects in reconstructive surgery. A total of 64 patients who underwent three-dimensional reconstruction of the alveolar ridge and insertion of endosseous implants for severe resorption were evaluated retrospectively. Despite the postoperative infection rate of 20.3% (13 patients), only 4.1% of the 266 inserted implants were lost in the long term. This indicates that augmentation using free autogenous iliac bone grafts and implants have a success rate of approximately 96% despite difficult initial situations. This success was mainly related to the soft tissue condition covering the graft. A technique for soft tissue dissection, especially in the maxilla, is presented.