Neurosurgical cadaveric and in vivo large animal training models for cranial and spinal approaches and techniques - a systematic review of the current literature.

INTRODUCTION: Due to its high complexity, neurosurgery consists of a demanding learning curve that requires intense training and a deep knowledge of neuroanatomy. Microsurgical skill development can be achieved through various models of simulation, but as human cadaveric models are not always accessible, cadaveric animal models can provide a reliable environment in which to enhance the acquisition of surgical dexterity. The aim of this review was to analyse the current role of animal brains in laboratory training and to assess their correspondence to the procedures performed in humans. MATERIAL AND METHODS: A Pubmed literature search was performed to identify all the articles concerning training cranial and spinal techniques on large animal heads. The search terms were 'training model', and 'neurosurgery' in association with 'animal', 'sheep', 'cow', and 'swine'. The exclusion criteria were articles that were on human brains, experimental fundamental research, or on virtual simulators. RESULTS: The search retrieved 119 articles, of which 25 were relevant to the purpose of this review. Owing to their similar neuroanatomy, bovine, porcine and ovine models prove to be reliable structures in simulating neurosurgical procedures. On bovine skulls, an interhemispheric transcalosal and retrosigmoid approach along with different approaches to the Circle of Willis can be recreated. Ovine model procedures have varied from lumbar discectomies on sheep spines to craniosynostosis surgery, whereas in ex vivo swine models, cadaveric dissections of lateral sulcus, median and posterior fossa have been achieved. CONCLUSIONS: Laboratory training models enhance surgical advancements by familiarising trainee surgeons with certain neuroanatomical structures and promoting greater surgical dexterity. The accessibility of animal brains allows trainee surgeons to exercise techniques outside the operating theatre, thus optimising outcomes in human surgical procedures.

Human tooth and root canal morphology reconstruction using magnetic resonance imaging.

BACKGROUND AND AIMS: Visualization of the internal and external root canal morphology is very important for a successful endodontic treatment; however, it seems to be difficult considering the small size of the tooth and the complexity of the root canal system. Film-based or digital conventional radiographic techniques as well as cone beam computed tomography provide limited information on the dental pulp anatomy or have harmful effects. A new non-invasive diagnosis tool is magnetic resonance imaging, due to its ability of imaging both hard and soft tissues. The aim of this study was to demonstrate magnetic resonance imaging to be a useful tool for imaging the anatomic conditions of the external and internal root canal morphology for endodontic purposes. METHODS: The endodontic system of one freshly extracted wisdom tooth, chosen for its well-known anatomical variations, was mechanically shaped using a hybrid technique. After its preparation, the tooth was immersed into a recipient with saline solution and magnetic resonance imaged immediately. A Bruker Biospec magnetic resonance imaging scanner operated at 7.04 Tesla and based on Avance III radio frequency technology was used. InVesalius software was employed for the 3D reconstruction of the tooth scanned volume. RESULTS: The current ex-vivo experiment shows the accurate 3D volume rendered reconstruction of the internal and external morphology of a human extracted and endodontically treated tooth using a dataset of images acquired by magnetic resonance imaging. The external lingual and vestibular views of the tooth as well as the occlusal view of the pulp chamber, the access cavity, the distal canal opening on the pulp chamber floor, the coronal third of the root canals, the degree of root separation and the apical fusion of the two mesial roots, details of the apical region, root canal curvatures, furcal region and interradicular root grooves could be clearly bordered. CONCLUSIONS: Magnetic resonance imaging offers 3D image datasets with more information than the conventional radiographic techniques. Due to its ability of imaging both hard and soft dental tissues, magnetic resonance imaging can be successfully used as a 3D diagnostic imaging technique in dentistry. When choosing the imaging method, dental clinicians should weight the benefit-risk ratio, taking into account the costs associated to magnetic resonance imaging and the harmful effects of ionizing radiations when cone beam computed tomography or conventional x-ray are used.