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.

Behandlung von frontobasalen Traumen und Polytraumen

BACKGROUND

This paper describes the historical development as well as current concepts of frontobasal fracture treatment by maxillofacial surgeons.

TREATMENT CONCEPT

Based on the experience of many years a diagnostic and therapeutic treatment concept was developed, which proved to be adequate in 320 patients with 90 frontobasal fractures in the last five years.

Orthognathic surgery in Melnick-Needles-Syndrome. Case report and review of the literature

Melnick-Needles Syndrome (MNS) is a congenital syndrome associated with severe architectural disorder of the skeletal system that can cause significant effects on the craniofacial skeleton including poor aesthetics, impaired speech and masticatory problems. The authors report a case of a female patient who experienced masticatory constraint, hindered speech and functional problems related to a severe bite dysfunction due to the mandibular hypoplasia and the underlying bony architectural disorder associated with MNS. The patient underwent bilateral sagittal split osteotomy (BSSO) to correct her skeletal malocclusion and improve the characteristic aesthetics and speech. The inherent bony abnormalities with their altered collagen structure presented unique challenges to orthognathic surgery in this patient with an unpredictable bone healing process. In MNS patients a fragile trabecular bone structure and an increased bleeding tendency is thought to delay or forestall wound healing. The patient was treated successfully with BSSO and monocortical plate fixation following a well-established algorithm from orthodontic preparation to surgical protocol. A very satisfying outcome has been achieved, concerning functional rehabilitation and aesthetic improvement. A review of the literature revealed that little is known about bone regeneration and fracture healing in cases with MNS.

Catenin expression in T1/2 carcinomas of the floor of the mouth

Reduction of the expression of catenin is a crucial step in the pathogenesis, progression and prognosis of many epithelial cancers including squamous cell carcinomas (SCCs). Catenin expression in oral carcinomas was evaluated in relation to clinico-pathological features in order to determine its value as a prognostic marker. Eighty-five patients with histologically proven T1/2 squamous cell carcinoma of the oral floor who underwent surgical treatment were eligible for the study. A tissue microarray consisting of multiple representative tissue cores of each carcinoma was composed. The expression levels of alpha, beta and gamma-catenins were determined immunohistologically. Correlation between clinical features and the expression of catenin proteins was evaluated statistically using Kaplan-Meier curves, log-rank tests and chi(2)-tests. Loss of alpha-catenin expression in carcinoma of the floor of the mouth correlated significantly with poor prognosis (P=0.05). Conversely, significantly reduced rates of lymph-node metastases were observed in alpha- and beta-catenin-positive T1 and T2 SCCs. Loss of gamma-catenin expression indicated a reduced survival rate in nodal-negative tumours (P=0.02). Catenin expression in carcinomas of the floor of the mouth seems to be a predictive parameter in the prognosis of T1 and T2 SSCs.

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.

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.

[Aggressive fibromatosis in the jaw and facial region with bone involvement. A review]

BACKGROUND

Aggressive fibromatosis (AF) involving bones of the head is rare and surgery is often complicated by a high recurrence rate. Interdisciplinary treatment is of the utmost importance to avoid extensive, mutilating resection. Two cases emphasize the difficulties in the management.

CASE REPORTS

A 67-year-old woman was referred to our unit with a blepharochalasis of the left upper palpebra and a palsy of the face on the left side. Her medical history included 12 operations over the previous 4 years for an extensive AF.

MATERIAL AND METHODS

Our review includes all case reports of AF involving bones of the head published between 1960 and 2004. Additionally, our two cases are presented. Signs, symptoms and outcome were analyzed in relation to different treatment options.

CONCLUSION

According to the literature, surgery is the most common treatment for AF in the head and neck region. Alternative modes of therapy must be considered because of the high recurrence rate and to avoid mutilating operations.

Investigation of cell adhesion to structured surfaces using total internal reflection fluorescence and confocal laser scanning microscopy

Adhesion of adherent cells on structured surfaces is influenced by the surface pattern given. Here, we designed a structured gold relief surface based on cell adhesion patterns we had previously observed. We analysed the geometric parameters and the overall distribution of focal adhesion kinase in focal adhesions on unstructured glass surfaces using optical microscopy. The basic structural elements obtained from this analysis were arranged in regular clusters that resembled the shape of a polarised migratory cell. In time-lapse studies we observed that the cells adhere preferentially to the gold pads and adopt the shape of the clusters. Staining of the actin cytoskeleton revealed that the actin filaments are aligned to the gold pads of the elementary structure.

Surgical reconstruction after subtotal ear resection in malignant melanoma of the ear

Surgery in malignant melanoma of the external ear often leads to substantial defects where reconstruction poses a difficult challenge. We describe an option of a one-step ear reconstruction after subtotal ear resection in malignant melanoma surgery. In a patient with a high-risk melanoma of the helical rim, a wide local excision was performed. Because of a metastasis-suspect lymph node in the parotid gland, surgery included asservation of the sentinel lymph node, neck dissection and parotidectomy. A complete reconstruction of the ear was achieved using a bilobed flap from the retroauricular and neck region with acceptable cosmetic and functional results by one-step surgery. One micrometastasis was detected in the nuchal region but not in the marked sentinel lymph node. An adequate one-step ear reconstruction as described may also be performed to the benefit of patients with high-risk melanomas, allowing early adjuvant therapy.

[Osteoblast reaction on SLA and microgrooved implant surfaces]

The osseointegration process of dental implants depends on the tissue reaction at the tissue-implant interface. Osteoblasts are the main cells responsible for the regulation of osteoinduction. The manner and kinetics of the tissue reaction crucially depend on the interaction between osteoblasts and the morphology of the implant surface. The aim of this study was to investigate osteoblast behaviour on different implant surfaces (smooth, microgrooved, SLA) under standardized conditions. For this in vitro investigation we used primary bovine osteoblasts. Attachment kinetics, proliferation rate and synthesis of bone-associated proteins were used as parameters for cell reaction. The results demonstrate that both attachment and adhesion strength of the primary cell surface interaction was higher on the microgrooved surfaces than on SLA surfaces. The proliferation rate of cells and the synthesis of bone-specific proteins were higher on microgrooved surfaces in contrast to SLA surfaces. Ultrastructural analysis revealed phenotypic osteoblast-like cells on smooth and microgrooved surfaces, whereas cells on SLA surfaces showed a more fibroblastic appearance. This study demonstrates that the morphology of the implant surface determined the subsequent osteoblast reaction. An optimal cell reaction was found at surfaces which are smooth in the microenvironment of osteoblasts.

Score system for elective tracheotomy in major head and neck tumour surgery

BACKGROUND

This study was designed to evaluate prognostic parameters for respiratory failure after major oropharyngeal resections in head and neck cancer surgery, focusing on a score system to identify patients requiring an elective tracheotomy and to avoid tracheotomy under emergency conditions.

METHODS

One hundred and fifty-two out of 928 patients with oropharyngeal cancers, treated between January 1993 and June 2000 at our hospital, fulfilled the inclusion criteria for a retrospective analysis. This collective underwent tumour resection in different regions of the oropharynx combined with bony resection of the mandible and neck dissection without primary tracheotomy. The reconstruction was accomplished using radial forearm flaps (n1 = 59) or local flaps (n2 = 93). These two groups were subdivided into patients treated post-operatively by tracheotomy due to respiratory failure (n1 = 26; n2 = 12) and those without such treatment (n1 = 33; n2 = 81). The database comprising tumour localization and size, staging, general medical condition, smoking and alcohol consumption was evaluated by logistic regression.

RESULTS

We developed a score system which predicts the likelihood of post-operative respiratory failure. For indication of tracheotomy, tumour size and localization, multimorbidity, alcohol consumption and pathologic chest X-ray findings were identified as significant parameters with different weightings. The predictive value for tracheotomy (yes/no) using the score system was 96.7% for the total collective.

CONCLUSION

The decision on whether or not an elective tracheotomy in major head and neck tumour surgery is necessary can be facilitated using this score system which is based on objective facts. It may reduce post-operative complications and contribute to safer treatment.

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.

Biological and biophysical principles in extracorporal bone tissue engineering. Part III

Over the last decade extracorporal bone tissue engineering has moved from laboratory to clinical application. The restoration of maxillofacial bones from cell harvesting through product manufacture and end-use has benefited from innovations in the fields of biomechanical engineering, product marketing and transplant research. Cell/scaffold bone substitutes face a variety of unique clinical challenges which must be addressed. This overview summarises the recent state of the art and future anticipations in the transplantation of extracorporally fabricated bone tissues.

Biological and biophysical principles in extracorporal bone tissue engineering

The aim of this review is to characterise the biological and biophysical background of in vitro bone tissue engineering. The paper focuses on basic principles in extracorporal engineering of bone-like tissues, considering parameters such as scaffold design, tissue construction, bioreactors, and cell stimulation in vivo and in vitro. Scaffolds have a key function concerning cellular invasion and bone formation. The intra-architectural scaffold geometry, as well as the scaffold material, play an important role in the process of bone regeneration. Various types of bioreactors have been tested for their utility in bone substitute fabrication that is clinically effective and reproducible. Sophisticated bioreactor systems are those that mimic the three-dimensional morphology and the mechanical situation of bones. Mechanical stimulation as well as other biophysical stimuli appear to be critical factors for proliferation and differentiation of bone cells and for bone mineral and structure formation. Furthermore an enhancement of bone regeneration by application of chemical stimulation factors is discussed.

Tierexperimentelle Evaluation des periimplant�ren Knochens bei zylindrischen gegen�ber konischen Implantattypen

BACKGROUND

The treatment of patients with early or immediately loaded dental implants has renewed interest in the behavior of osseointegration at the implant surface. Whereas it is generally accepted that peri-implant tissue formation and mineralization are dependent on the local mechanical environment in the interface zone, controversies exist concerning the impact of implant design on peri-implant bone formation. The aim of the present study was the in vivo evaluation of peri-implant bone formation by two different implant systems: cylindrical (ITI) versus conical (ILI).

MATERIAL AND METHOD

A total of 60 implants (30 ITI and 30 ILI) were placed in the cranial and caudal part of the tibia of eight Göttinger minipigs. Half of the minipigs were sacrificed at 7 days and 28 days of osseointegration. Implant-containing bone specimens were prepared for histological and ultrastructural investigations.

RESULTS

Histological and scanning electron-microscopic investigations showed a direct contact of bone-like minerals over the whole implant surface from day 7 of implant/bone interaction. Whereas the ILI implant showed direct contact up to the top of the crestal bone, ITI implants demonstrated a crestally located narrow gap without ossification over the whole experimental period.

CONCLUSION

Our investigations support the hypothesis of an implant design-inherent emergence and maintenance of crestal bone.

Biological and biophysical principles in extracorporal bone tissue engineering

Advances in the field of bone tissue engineering have encouraged physicians to introduce these techniques into clinical practice. Bone tissue engineering is the construction, repair or replacement of damaged or missing bone in humans or animals. Engineering of bone can take place within the animal body or extracorporal in a bioreactor for later grafting into the body. Appropriate cell types and non-living substrata are minimal requirements for an extracorporal tissue engineering approach. This review discusses the biological and biophysical background of in vitro bone tissue engineering. Biochemical and biophysical stimuli of cell growth and differentiation are regarded as potent tools to improve bone formation in vitro. The paper focuses on basic principles in extracorporal engineering of bone-like tissues, intended to be implanted in animal experiments and clinical studies. Particular attention is given in this part to the contributions of cell and material science to the development of bone-like tissues. Several approaches are at the level of clinical applicability and it can be expected that widespread use of engineered bone constructs will change the surgeon's work in the near future.

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.

Combined space management through Delaire/Joos osteotomy and postoperative orthodontic treatment. A retrospective longitudinal study

The diagnostic records of all patients who had undergone Delaire/Joos osteotomy with mandibular setback at the Muenster University Hospital (period 1995-2000, n=22) were used for space management evaluation in the context of combined surgical-orthodontic treatment.Twenty-eight dental spaces were present prior to the start of treatment and 14 were created by extracting teeth as a pretreatment measure. In two patients, unilateral setback was performed according to Obwegeser/Dal Pont. Thus, 42 tooth-bounded spaces were present at the time of Delaire/Joos osteotomy with mandibular setback, most of them in the first molar region, followed by the second premolar region. A significant space reduction was achieved by the surgical intervention, but not by the subsequent orthodontic treatment. The best results with respect to complete space closure by orthognathic surgery/orthodontic treatment without the need for subsequent prosthetic rehabilitation were recorded in the second premolar region. In the absence of spaces and with a similar long-term prognosis for all potentially extractable teeth and adequate space for the necessary surgical repositioning, the second premolars should therefore be regarded as the 'extraction teeth of choice' for mandibular setback within the context of Delaire/Joos osteotomy.

Aneurysmal bone cyst of the mandible: a case report

The case of a 6-year-old boy with a rapid growing mass in the right angle of the mandible that clinically and radiographically resembled a malignant lesion is presented. The biopsy specimen showed an aneurysmal bone cyst. The patient was treated surgically via extraoral approach including immediate mandibular reconstruction with with iliac crest bone. The literature is briefly reviewed.

Are collimated low-dose digital radiographs valid for performing Delaire's architectural analysis?

Computed radiography (CR) provides the dynamic exposure range to reveal objects in film areas exposed by very low X-ray exposure. Conventional cephalometric radiographs are normally beam limited to the facial skeleton. The cranial vault and cervical vertebra are collimated and only exposed by extra-focal radiation and scatter. We hypothesize that, on conventional cephalometric radiographs obtained with CR, image data of collimated film areas can be enhanced for reliable performance of Delaire's cephalometric analysis of the entire skull. Therefore the aim of the present study was to compare the reproducibility of landmark placement on normal and underexposed film areas of CR images. Intra- and inter-observer reproducibility of landmark identification was evaluated on 200 randomly selected radiographs by calculating the error radius of repeated landmark placements. A paired-samples t-test revealed differences (P< 0.001) between intra- and inter-observer reproducibility. Intra-observer accuracy was influenced (P< 0.001) by variability of suture obliteration (bregma). Identification of landmarks in areas of extra-focal radiation showed no difference (P> 0.05) from that of landmarks inside the normally exposed area. CR offers the opportunity to perform of a full cranial analysis on a cephalometric radiograph collimated to the facial region.

Primäre Implantatstabilität bei unterschiedlichen Knochenaufbereitungstechniken

The treatment concept of osseointegration is based on a stable embodiment of implants in bone and the maintenance of stability during functional load. A goal of the surgical preparation technique is therefore to obtain a stable and firm implant anchorage. The aim of this study was to evaluate implant stability after different surgical treatment of the bony implantation bed. Thirty cylindrical solid-screw-shaped implants with standard SLA ITI configuration were implanted into the explanted mandibles of five minipigs. The implant sites were prepared either by a conventional burr technique (group A), by burr technique with additional thread cutting (group B), or by the osteotome technique (group C). Primary implant stability was evaluated by resonance frequency analysis and removal torque test. The average value of the resonance frequency analysis (RFA) was 6000+/-469 cycles/s in group A, 5700+/-557 cycles/s in group B, and 5540+/-527 cycles/s in group C. Removal torque values of group A (507+/-57 Nmm) were significantly higher than those of group B (466+/-45 Nmm) and group C (240+/-31 Nmm) (between group A and C p<0.05, group A to B p=0.39, and B to C p<0.05). It can be concluded from this study that the conventional burr technique achieves a statistically significantly better primary bone anchorage than the osteotome technique.

[Odontogenic foci--possible etiology of urticaria?]

Recent studies have shown that chronic odontogenic infections could pose a risk for myocardial infarction, cerebral ischemia, and arteriosclerosis. However, the correlation between urticaria and dental infections has rarely been examined so far. Therefore, we performed a case-control study using a standardized questionnaire and examination. We investigated 66 patients suffering from an acute or chronic urticaria and 65 age- and sex-matched healthy patients as a control group. Dental status was determined by a so-called total dental index (TDI) which primarily reflects caries, periodontitis, periapical lesions, and nonvital and missing teeth. All 66 patients were referred from the department of dermatology. After their treatment in hospital, all patients received a questionnaire with questions on intensity and localization of the urticaria. The TDI of the urticaria patients was slightly better ( n=66; 2.6+/-1.98) than that of the control group ( n=65, TDI=3.3+/-1.86). Subsequently, it was determined if the urticaria had receded after dental treatment. In conclusion, chronic dental infections do not seem to correlate with an increased risk for urticaria.

Experimentelle und klinische Studie zur Stabilität einer Osteosyntheseplatte für den atrophen Unterkiefer

BACKGROUND

The high rate of complications led us to develop a new osteosynthesis plate for the treatment of the fractured atrophied mandible. The development of the new so-called pencil-bone plate is based on the 2.0 mini-plate system manufactured by the Medartis Company.

MATERIAL AND METHODS

Finite elements (FE) analysis of the new plate as well as flexibility experiments were undertaken, and 14 patients with 16 fractures of the atrophied mandible were treated with the pencil-bone plate between October 2000 and November 2001.

RESULTS

The results clearly show that the pencil-bone plate reacted in both the FE model and the static flexibility experiment in a more stable way than a standard 2.0 plate. In 13 patients, healing proceeded without serious complications; all of the patients showed subjective, nearly unchanged chewing, speaking, and swallowing abilities and no complications occurred when wearing dentures. One patient underwent surgical intervention after a new trauma.

CONCLUSION

The clinical outcome of the treated fractures confirmed the experimental results, which proved the high stability of the plate in the area of the fracture site. Due to the mini-plate format the intraoral application of the plate is possible without problems. The intraoral access allows rapid operation followed by a minimum of morbidity. A great advantage of the small dimension system is the unrestricted wearing of dentures after the application.

Evaluation of accuracy of insertion of dental implants and prosthetic treatment by computer-aided navigation in minipigs

The survival of loaded implants is critically dependent on their biomechanical stability. We have used a computer-guided navigation technique to evaluate the accuracy of computer-assisted insertion for immediately-loaded implants in minipigs. On the basis of computed tomographical data, the Robodent system was used for preoperative planning and guidance of inserting the implant. An optical tracking system allowed positioning of the implant and immediate prosthetic rehabilitation by inserting it in a plaster model and during the operation. Postoperative computed tomograms (CT) showed that the implants were placed precisely in the preoperatively planned position. The accuracy achieved corresponded well with the spatial resolution of the CT used. Immediate placement of the prefabricated crowns resulted in favourable occlusal positioning. Histological cross-sections showed that the implants were biomechanically stable. The accuracy of insertion of oral implants illustrated here suggests that insertion and prosthetic modelling of implants may benefit from computer-assisted navigation.

[Experimental study on the biomechanical stability of different internal fixators for use in the mandible]

BACKGROUND

Comparative studies of different forms of osteosynthesis require that biomechanical and biological criteria be observed. The conditions in experimental studies should be as close as possible to the in vivo situation. The aim of our study was to develop a fracture model that would allow determination of the micromovements in the gap tissue following different forms of internal fixation in fractured human mandibles.

METHODS

Micromovements in the gap tissue of five human mandibles treated with different osteosynthetic systems (DCP, EDCP, Miniplates, 3-D systems) following osteotomy or fracture in the region of the corpus and median region were investigated by means of strain gauges. By fitting the human mandibles in plaster according to a method of our own it was possible to create fractures at predictable and comparable localizations.

RESULTS

Our investigations show that the micromovements in the gap tissue of osteotomied and fractured mandibles are different and not dependent on the form of osteosynthesis applied. Physiological micromovements in the gap tissue were found under strain for all osteosynthetic systems used in fractured and congruently reset mandibles.

DISCUSSION

Our fracture and osteosynthesis model allows the quantitative determination of micromovements in the gap tissue and shows the importance of ideal realignment, which has a decisive influence on micromovements in the gap tissue.

Indications for treatment of subcondylar mandibular fractures

BACKGROUND AND OBJECTIVES

The purpose of this study was to establish a reliable criteria for implementation of either an open surgical or a closed conservative treatment of subcondylar fractures, based on clinical data and analytical mathematical model.

METHODS AND MATERIALS

A total of 512 subcondylar fractures were treated during a 3-year period. Of these, 256 were fractures characterized by either displacement or dislocation of the proximal (condylar) segment. Patients were treated with open reduction and internal fixation (ORIF) or closed reduction (CR) techniques. Patients were evaluated pre- and postoperatively by clinical examination, 3-dimensional axiography, radiographic imaging, and ultrasonography. A mathematical model was developed for estimating the loss of vertical ramus height.

RESULTS AND/OR CONCLUSIONS

When the displacements were less than 37 degrees from the sagittal axis of the ascending ramus, the ensuing loss of vertical height was negligible when fractures were treated by conservative techniques. When the displacements exceeded 37 degrees, the fractures resulted in a significant decrease of vertical ramus height. Based on these data, 37 degrees appears to be the point for decision of whether to use closed or open treatment.

Ultrasonographic versus conventional diagnostic procedures in dislocated subcondylar mandibular fractures

In patients with severe craniomaxillofacial trauma, immediate attention is directed primarily to the early diagnosis of cervical spine injuries, intracranial injuries, respiratory difficulties, and vascular compromises. Diagnostic studies, such as computed tomography scans, are sometimes not useful for the evaluation of mandibular fractures, since cuts are performed too superiorly. The plane radiographs obtained in emergency settings are frequently of minimal diagnostic value. Fractures of the mandibular symphysis, body, and angles are easily identified clinically; subcondylar fractures, however, are not directly accessible for clinical examination. The evaluation of suspected dislocated subcondylar fractures with the aid of ultrasonography is reliable, highly sensitive and specific, and cost-effective.

[Evaluating angiogenesis and osteogenesis modified by vascular endothelial growth factor (VEGF)]

PURPOSE

This intention of this study was to investigate the influence of controlled release of vascular endothelial growth factor (VEGF) on angiogenesis and osteogenesis in a mandibular defect model.

METHODS

A total of 56 rabbits were operated and bicortical holes were placed in the mandible. The defects were filled with collagen type I implants, collagen implants complexed with 0.8-microgram VEGF165, or left without any filling. After 3, 7, 14, and 28 days specimens were taken and histologic, histomorphometric, and immunohistologic analyses were carried out concerning density of vessels, total surface of vessels, bone surface, and bone density.

RESULTS

The number of vessels was increased in all groups up to 14 days, followed by physiologic regression in the control groups, whereas the study group showed persistently high numbers. The density of regenerated bone was significantly higher in the study group.

CONCLUSION

The activation of angiogenesis using VEGF165 leads to more intensive angiogenesis and bone regeneration.

First experience with a public domain computer-aided surgical system

The outcome of complex craniofacial operations is critically dependent on careful and accurate preoperative planning. Recent advances in computer technology enable the surgeon to do surgical simulations directly on to a computer terminal. We describe the clinical application of a public domain-based computer-aided system in craniofacial surgery. Operation planning was based on clinical investigations and radiological images, with particular use of a virtual three-dimensional surgical simulation. Three patients with complex craniofacial malformations were admitted for orbital correction. Surgical simulation defined numerically the extent of bone movements and the extent of resection areas. Operations were guided by the virtual planning. The outcome was compared with the planning to assess the accuracy of the operative correction. Our first experience confirms that computer-assisted simulation is a reliable and useful tool that improves surgical planning and helps to evaluate the surgical outcome.

[Possibilities and limitations in evaluating treatment concepts in lip-jaw-palate clefts]

BACKGROUND

Recently, government and medical practitioners have shown considerable interest in the discipline of evidence-based medicine.

LITERATURE RESEARCH AND RESULTS

In this study, we investigated the literature concerning treatment concepts in cleft surgery according to criteria of evidence-based medicine. Over the last decade 996 articles on cleft patients were published, 181 of which were studies evaluating the clinical outcome of distinct treatment options. Only 57 studies proved to be classifiable due to a well-described study protocol. One treatment study of cleft patients reached the strength of evidence grade I and strength of recommendation grade A, whereas all other studies had a lower evidence rating.

DISCUSSION

The reasons behind these findings seem to be due to problems faced by the specialty of this disease.

Late effects of radiotherapy on oral mucosa in humans

In order to gain further understanding of the late effects of radiotherapy on oral mucosa, we analysed the histomorphological alterations, the cell populations in the subepithelial tissue, and the endothelial expression pattern of different adhesion molecules. Biopsies were taken from patients before irradiation, directly after 60 Gy, and 6-12 months after radiotherapy. Besides the histomorphological evaluation of the vessels, the endothelial expression of ICAM-1, VCAM-1 and E-selectin was determined as well as the distribution of LFA-1-, Mac-1-, VLA-4-, RM3/1-, 27E10- and 25F9-bearing cells in the subepithelial tissue. The expression of ICAM-1 was downregulated after radiotherapy, whereas the percentage of LFA-1- and VLA-4-bearing cells increased. VCAM-1 remained at low levels. The subepithelial infiltration was still dominated by RM3/1-positive macrophages. The number of vessels decreased, while the lumen of the remaining vessels increased. In conclusion, the late effects of radiotherapy are characterized by a decreased number of blood vessels and by significantly different expression patterns of the adhesion molecules studied, and of integrins and macrophage subpopulations, compared to the conditions before irradiation and directly after irradiation with 60 Gy.

Influence of distraction rates on the temporomandibular joint position and cartilage morphology in a rabbit model of mandibular lengthening

PURPOSE

Although various aspects of bone formation during distraction osteogenesis have been studied extensively, there are only limited experimental data concerning the influence of mandibular distraction rates on structural alterations in the temporomandibular joint (TMJ). In this study, a rabbit model of unilateral mandibular distraction was used to test the effects of various strain schedules on the position and morphology of the TMJ.

MATERIAL AND METHODS

Fifty-two immature white female rabbits were used. The distraction procedure was performed using physiologic (2,000 microstrains, 1 per day) and elevated strain magnitudes (20,000 microstrains, 1 per day), as well as high strain magnitudes (200,000 and 300,000 microstrains, 1 per day). The investigation of the TMJ included clinical, radiologic, and histologic aspects.

RESULTS

Clinical and radiologic examinations at the end of the distraction period showed no evidence of joint luxation even at maximal distraction rates. Histologic and ultrastructural analyses revealed a positive correlation between the degree of mechanical loading and the development of degenerative alterations in the cartilage. In samples distracted at hyperphysiologic strain magnitudes, all cartilaginous layers were reduced in the regions of the TMJ that had been exposed to the higher pressure forces. The fibrous layer became nearly completely destroyed.

CONCLUSIONS

These experimental data show that distraction schedules with single but hyperphysiologic loads may lead to degenerative or even early arthrotic changes in the condyle. These data support the principle that distraction protocols should be performed without extensive mechanical loading on the TMJ.

Mechanical tension in distraction osteogenesis regulates chondrocytic differentiation

Differentiation of chondrocytes to cells of osteoblastic phenotype occurs during an interim period of bone development, fracture repair and distraction osteogenesis. To study the relationship between tension-stress and chondrogenesis, uniaxial strains (0 microstrains, 2000 microstrains, 20000 microstrains, 200000 microstrains, 300000 microstrains) were applied in a rabbit model of mandibular distraction osteogenesis. The results demonstrated that cell differentiation, apoptosis and tissue development in the newly formed gap tissue showed a correlation to the applied strain magnitudes. Only strains of 20000 microstrains resulted in a statistically significant (P<0.05) formation of cartilage struts with embedded chondrocyte-like cells. However, chondrocyte-like cells were rarely detected in samples distracted at lower or higher strain magnitudes. Osteoblasts appeared to replace cartilaginous matrix by mineralized bone matrix. The phenotypic change from chondrocytes to osteoblasts was accompanied by a decreased proteoglycan synthesis. a change in the expression from type II collagen towards type I and involved asymmetric cell divisions and apoptotic cell death. Therefore, we suggest that mechanical strain is an external stimulus responsible for phenotypic cell alterations.

Microstructural investigations of strain-related collagen mineralization

Distraction osteogenesis in rabbit mandibles after osteotomy can be used as an experimental model to study the microstructural features of mineralization of callus under defined mechanical loads. Our aim was to study the relation between the micromotions in the gap and the resulting features of mineralization of the matrix. We found that assembly of collagen and formation of crystals depended on the magnitude of the mechanical stress applied. At physiological bone strains (2000 microstrains), the callus had collagen type I in a mature bone-like extracellular arrangement, whereas at 20000 microstrains bundles were orientated predominantly towards the tension vector. Maximum loads (200000 microstrains) resulted in disorganized assembly of the collagen. Quantitative energy-dispersive analysis by X-rays confirmed that high strains were associated with substantially lower concentrations of calcium and phosphate. In contrast to bone-like apatitic formation of crystals at physiological strains, significantly fewer but larger crystals were detected by electron diffraction analysis in samples exposed to high strains. We suggest that mechanical stress regulates the assembly and mineralization of collagen during distraction osteogenesis.

Comprehensive management of cleft lip and palate deformities

PURPOSE

The controversy regarding the timing of repair of the deformities associated with cleft lip and palate still exists. The goal of this article is to present a versatile, universal philosophy of management of these deformities involving early repair.

PATIENTS AND METHODS

Over 20 years, 2,698 new patients with cleft lip and palate deformities were treated. These included 1,298 unilateral and 320 bilateral cleft lip and palate patients. The remaining patients (1,018) had isolated palatal clefts. All patients were operated according to the same protocol and the same surgical procedure. The treatment philosophy was based on early, wide myoperiosteal-periosteo-sutural reconstruction by a modified Delaire functional cheilorhinoplasty and alveolar gingivoperiosteoplasty at 3 months, followed by soft and hard functional palatoplasty at 9 months.

RESULTS

All patients were followed longitudinally and retrospectively. The parameters investigated were facial symmetry, presence or absence of growth retardation, and oropharyngeal and nasal function. The parameters studied indicated that when this treatment schedule was followed and the procedures were performed on time and according to the protocol, there was minimal growth retardation of the maxilla. When early gingivoperiosteoplasty was performed in 25% of the patients there was a sufficient amount of alveolar bone for eruption of the primary and permanent dentition. This negated the need for secondary alveolar bone grafting. The development of the upper lip was harmonious, and usually no further corrective procedures were necessary. The nose was usually well developed and functionally normal.

CONCLUSION

Optimal rehabilitation of the patients was achieved by following the principles and treatment strategies described. If the treatment principles are not incorporated in the functional repair (ie, joining of the primary and the secondary growth centers during corrective procedures), compromised results are to be expected.

[Surgical procedures in mouth, jaw and facial surgery in Thiel embalmed body donors]

METHODS

This study investigates whether human cadavers embalmed according to Thiel can be used for research and education in oral-maxillo-facial surgery. Different surgical approaches were tested on such cadavers. The usability of the specimen was judged jointly by anatomists and surgeons. Color, structure, and consistency of the different tissues were comparable to vital conditions. Thiel's embalming technique applied to human cadavers provides an optimal basis for research and for basic and postgraduate medical education.

Imaging of cartilage and mimic muscles with MRI: anatomic study in healthy volunteers and patients with unilateral cleft lip and palate

OBJECTIVE

The aim of the study was to visualize different soft tissues in the perioral, nasal, and paranasal region by means of magnetic resonance imaging (MRI) in patients with unilateral cleft lip and palate (UCLP).

DESIGN

In this descriptive study, images of different MRI systems were assessed and compared.

METHOD

MRI was applied in five consecutive patients operated on for UCLP who underwent secondary lip and nasal correction, two patients who had not had UCLP operations, and five healthy volunteers as controls. The mimic muscles, vessels, and nasal cartilages were evaluated.

RESULTS

It was possible to visualize different parts of the paranasal and perioral mimic muscles and their interlacement in the upper lip. The nasal cartilages were also visible, and the changes after operation were demonstrated.

CONCLUSIONS

MRI shows differentiated visualization of soft tissues in the cleft region and their changes after surgery. It is a valuable tool in the preoperative planning and postoperative follow-up in patients with UCLP.

Three-dimensional magnetic resonance imaging of the orbit in craniofacial malformations and trauma

Craniofacial malformations and trauma often lead to changes in orbital soft tissues, requiring surgical correction of both hard and soft tissues. Computed tomographic scans and 3-dimensional reconstructions are the optimal tools for evaluation of the bony structures. However, there is no equivalent method for the orbital soft tissues. The aim of this study was to establish a 3-dimensional magnetic resonance imaging (3-D MRI) technique that allows a differentiated visualization of the different types of soft tissue in the orbit. A total of 8 patients with different pathologic conditions of the orbit was examined. Five of these patients underwent secondary correction after trauma, and 3 had craniofacial malformations. The 3-D reconstruction was performed in the volume-rendering technique after acquisition of 3-mm axial slices. It was shown that a differentiated visualization of the orbital soft tissues is possible. Although the thin bony structures have a weak signal and, therefore, the imaging is poor, reliable reconstruction of the globe was achieved by different radiologists because of its circular delimitation from the bone. This technique is an additional support in the planning of orbital surgery.

[Mechanical stimulation of osteoblasts in cell culture]

BACKGROUND

Mechanical loading of bone is known to play a crucial role in bone remodeling and regeneration. Whereas the clinical effects of mechanically modulated bone healing have been extensively studied, less is known about the underlying mechanisms on a cellular level. This study was aimed at investigating the effects of uniaxial strains on osteoblast-like cells in culture. Mechanical loading was applied in physiological and hyperphysiological magnitudes. Nonstimulated cultures served as controls.

RESULTS

Cultured primary bovine periosteal cells exhibited phenotypic features of osteoblast-like cells. Application of physiological strains (2,000 mu strain) led to a bone-specific expression of extracellular matrix proteins (osteonectin, osteocalcin, collagen type I). Hyperphysiological loads (10,000 mu strain) were associated with an increased synthesis of proteoglycans. Proliferation of cells was higher than the controls at 10,000 mu strain and showed no difference from physiologically loaded osteoblasts.

DISCUSSION

Our study demonstrates that physiological loading of osteoblast-like cells enhances the regenerative capacity of bone, whereas hyperphysiological loads may impair bone regeneration.

Bone loading pattern around implants in average and atrophic edentulous maxillae: a finite-element analysis

INTRODUCTION

Oral implants placed in the maxilla, especially the posterior region, have a lower success rate than those placed in the mandible. Poor bone quantity and quality have been suggested as a reason for this differential success rate.

OBJECTIVE

The purpose of this study was, therefore, to evaluate stress and strain distributions around loaded implants in the normal and atrophic maxilla by finite-element (FE) analyses.

MATERIAL

FE models of a solitary implant were generated to determine stresses and strains in the bone adjacent to the implant surface under loading conditions.

STUDY DESIGN

Different bony situations and implant lengths were used in a FE model. Static loads were applied axially and the resulting stresses and strains calculated.

RESULTS

Bone quality and quantity play a major role in decreasing bone strains adjacent to the implant surface under loading. It was found that stresses were more homogeneously distributed when more spongy bone was present. Decreased bone height was found to have less pronounced effects on strain and stress alterations than poor bone quality. Atrophic bony dimensions in combination with poor bone quality were associated with surface strains exceeding physiological levels (> 6,000 microstrains).

CONCLUSION

Our investigation indicates that supraphysiological bone strains adjacent to the implant surface should be expected under mechanical loading in the atrophic maxilla.

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.