Chirurgische Untergesichtsverlängerung bei der Therapie von Patienten mit Klasse-II-Dysgnathien und skelettal tiefem Biss – "Short-face- Syndrom"

Among Angle Class II patients scheduled for orthognathic surgery, those with short face syndrome with skeletal deep bite only make up a small portion. Nevertheless, it represents a complex challenge for the orthodontist as well as for the surgeon with respect to the individual treatment goals. The harmony of facial relations is impaired in these patients: The skeletal lower face and consequently the soft tissue profile show a deficit in height compared to the midface. Lengthening of the lower face with its respective effect on facial aesthetics can only be corrected by causal therapy, i.e., a combined approach with surgical enlargement of the gonion angle. In this study, a therapy concept specifically suited for the correction of Class II deformities with short face syndrome is presented. Consequences for the skeletal and dental situation with their benefit for extraoral appearance were tested in a clinical trial (n=15, patients with class II deformities and short face syndrome). To evaluate skeletal and dental changes, cephalograms were taken prior to initiation of orthodontic treatment, 3 days after surgery but before initiation of postsurgery orthodontics, and 1 year after the end of treatment.     

Repair of human skull defects using osteoinductive bone alloimplants

To estimate the efficacy of cranioplasty in clinical practice, autolyzed, antigen-extracted, allogenic (AAA) bone was prepared from cortical bones of human organ donors. AAA bone implants consisted of completely demineralized bone powder, completely demineralized pliable bone chips, surface-demineralized bone chips with pliable crevices, surface-demineralized rigid bone chips, or combinations thereof. 21 patients received AAA bone cranioplasties and were followed-up for between 12 and 58 months (average: 29 months). No infection or rejection of any of the AAA bone implants occurred. X-ray assessments as well as bone scintigraphies revealed osseous integration and remodelling of the AAA bone implants with minimal resorption, with the exception of completely demineralized AAA bone chips which showed partial resorption (2 cases). However, the partial resorption of completely demineralized AAA bone chips ceased after the implants had been remodelled. In 4 cases, the osteosynthesis material was removed between 10 and 18 months after the cranioplasty. In another case, a re-entry was necessary because of recurrence of an intracranial tumor. All of these five AAA bone reconstructions showed bleeding surfaces and osseous consolidations at the time of re-entry. A bone biopsy taken from one of these cranioplasties showed osteoinduction on the surface of the AAA bone implants. This first clinical review of cranial reconstructions using osteoinductive AAA bone implants emphasizes the therapeutical application of AAA bone for cranioplasty. Large AAA bone chips from human skull bones facilitate the reproduction of the skull's convexity especially when combined with preoperative stereolithography-based planning.     

Analysis of interfacial fracture in dental restorations

Objectives

To provide a brief summary of the background theory of interfacial fracture mechanics and develop an analytical framework that identifies the critical factors for the analysis of the initiation and propagation of adhesion failure in composite restorations.

Methods

A conceptual framework utilizing interfacial fracture mechanics and Toya's solution for a partially delaminated circular inclusion in an elastic matrix, which can be applied (with caution) to approximate polymer curing induced cracking about composite resins for class 1 cavity restorations.

Results

The findings indicate that: (1) most traditional shear tests are not appropriate for the analysis of the interfacial failure initiation; (2) material properties of the restorative and tooth material have a strong influence on the energy realize rate; (3) there is a strong size effect; and (4) interfacial failure once initiated is characterized by unstable propagation along the interface almost completely encircling the composite.

Significance

The work is important for the analysis of the reliability of composite class I restorations and provides an adequate interpretation of recent adhesion debonding experimental results utilizing tubular geometry of specimens. The approach clearly identifies the critical parameters including; curing strain, material modulii, size and interfacial strain energy release rate for reliable development of advanced restorative materials.     

Mandibular interpositional and onlay bone grafting for treatment of mandibular bony deficiency in the edentulous patient

The development of interpositional and onlay bone grafting techniques for atrophic mandibles is reviewed. A further modification of the visor osteotomy is presented along with follow-up evaluation of the conditions of 16 patients. Results of radiographic measurements show the procedure to be stable, vertical resorption of the augmented mandible in the body regions being 11.2% over a mean follow-up of 8.8 months. Neurosensory evaluation showed altered sensation and dysesthesia as a significant problem in these patients. The results are presented and discussed.     

Profile Changes Following Maxillary Impaction and Autorotation of the Mandible

OBJECTIVE: The aim of this study was the evaluation and prediction of profile changes after Le Fort I osteotomy including maxillary impaction and subsequent autorotation of the mandible. MATERIALS AND METHODS: A group of 42 patients (32 female, 10 male) underwent a Le Fort I osteotomy with posterior impaction after preoperative orthodontic treatment. No surgical intervention in the mandible was performed. Pre- and postoperative lateral cephalograms of each patient were analyzed in two steps using the Wilcoxon and Mann-Whitney U test. All patients were evaluated for vertical and sagittal skeletal and soft tissue changes. These results led to further classification into three groups according to the type and extent of maxillary impaction. These groups included parallel impaction, posterior impaction with additional anterior subsidence, and posterior impaction only. RESULTS: The results of the first evaluation step revealed that the chin had advanced on average by 79%, while the lower face was shortened by as much as 70% in the pogonion point. However, the second evaluation showed that the type and extent of maxillary impaction led to significant changes in these parameters. Parallel maxillary impaction resulted in 100%, posterior impaction in 80% and posterior impaction with anterior subsidence in 50% advancement of the mandible in the pogonion point in relation to the distance covered during impaction. CONCLUSION: This study showed that the change in the facial profile caused by autorotation of the mandible after Le Fort I osteotomy and maxillary impaction can be predicted in relation to the dimensions of maxillary impaction.     

Development and maturation of the fibrous components of the arterial roots in the mouse heart

The arterial roots are important transitional regions of the heart, connecting the intrapericardial components of the aortic and pulmonary trunks with their ventricular outlets. They house the arterial (semilunar) valves and, in the case of the aorta, are the points of coronary arterial attachment. Moreover, because of the semilunar attachments of the valve leaflets, the arterial roots span the anatomic ventriculo‐arterial junction. By virtue of this arrangement, the interleaflet triangles, despite being fibrous, are found on the ventricular aspect of the root and located within the left ventricular cavity. Malformations and diseases of the aortic root are common and serious. Despite the mouse being the animal model of choice for studying cardiac development, few studies have examined the structure of their arterial roots. As a consequence, our understanding of their formation and maturation is incomplete. We set out to clarify the anatomical and histological features of the mouse arterial roots, particularly focusing on their walls and the points of attachment of the valve leaflets. We then sought to determine the embryonic lineage relationships between these tissues, as a forerunner to understanding how they form and mature over time. Using histological stains and immunohistochemistry, we show that the walls of the mouse arterial roots show a gradual transition, with smooth muscle cells (SMC) forming the bulk of wall at the most distal points of attachments of the valve leaflets, while being entirely fibrous at their base. Although the interleaflet triangles lie within the ventricular chambers, we show that they are histologically indistinguishable from the arterial sinus walls until the end of gestation. Differences become apparent after birth, and are only completed by postnatal day 21. Using Cre‐lox‐based lineage tracing technology to label progenitor populations, we show that the SMC and fibrous tissue within the walls of the mature arterial roots share a common origin from the second heart field (SHF) and exclude trans‐differentiation of myocardium as a source for the interleaflet triangle fibrous tissues. Moreover, we show that the attachment points of the leaflets to the walls, like the leaflets themselves, are derived from the outflow cushions, having contributions from both SHF‐derived endothelial cells and neural crest cells. Our data thus show that the arterial roots in the mouse heart are similar to the features described in the human heart. They provide a framework for understanding complex lesions and diseases affecting the aortic root.     

Ultrasound-based elastography: a novel approach to assess radio frequency ablation of liver masses performed with expandable ablation probes: a feasibility study

OBJECTIVE: The purpose of this study was to evaluate the technical feasibility of ultrasound-based elastography as a tool for assessing the size and shape of the coagulation necrosis caused by radio frequency ablation (RFA) probes using expandable electrodes ex vivo as well as in a patient with a liver metastasis. METHODS: A commercially available expandable RFA probe was used to create a 3-cm ablation in a piece of bovine liver. The ablation probe was used in situ to induce tissue deformation for elastography before and after ablation. Ultrasonic radio frequency data were processed to generate elasticity strain images. The appearance of the ablation zone was compared with magnetic resonance imaging and a gross section specimen. One patient with malignant metastatic disease to the liver and a clinical indication for RFA was investigated for the feasibility of percutaneous elastography of RFA using the same technique. Sonographic strain images were compared with the appearance of the nonenhancing ablation zone on contrast-enhanced computed tomography. RESULTS: Ex vivo, the ablation zone on ultrasound-based elastography was represented by an area of increased stiffness and was well demarcated from the nonablated surrounding tissue. The size and shape of the ablated zone on the strain image correlated well with the gross specimen and the magnetic resonance imaging appearance. Strain images obtained from the patient showed results similar to those of the ex vivo experiment and correlated well with the nonenhancing area of ablation on contrast-enhanced computed tomography. CONCLUSIONS: Ultrasound-based elastography may be a promising tool for displaying the ablation zone created by expandable RFA probes.     

The initial effects of a Mulligan's mobilization with movement technique on dorsiflexion and pain in subacute ankle sprains

Physiotherapists frequently use manipulative therapy techniques to treat dysfunction and pain resulting from ankle sprain. This study investigated whether a Mulligan's mobilization with movement (MWM) technique improves talocrural dorsiflexion, a major impairment following ankle sprain, and relieves pain in subacute populations. Fourteen subjects with subacute grade II lateral ankle sprains served as their own control in a repeated measures, double-blind randomized controlled trial that measured the initial effects of the MWM treatment on weight bearing dorsiflexion and pressure and thermal pain threshold. The subacute ankle sprain group studied displayed deficits in dorsiflexion and local pressure pain threshold in the symptomatic ankle. Significant improvements in dorsiflexion occurred initially post-MWM ( F(2,26) = 7.82, P = 0.002 ), but no significant changes in pressure or thermal pain threshold were observed after the treatment condition. Results indicate that the MWM treatment for ankle dorsiflexion has a mechanical rather than hypoalgesic effect in subacute ankle sprains. The mechanism by which this occurs requires investigation if we are to better understand the role of manipulative therapy in ankle sprain management.