Computer Assisted Planning in Cranio-Maxillofacial Surgery

Abstract

In cranio-maxillofacial surgery physicians are often faced with the reconstruction of massively destroyed or radically resected tissue structures caused by trauma or tumours. Also corrections of dislocated bone fragments up to the complete modeling of facial regions in cases of complex congenital malformations are common tasks of plastic and reconstructive surgeons. With regard to the individual anatomy and physiology, such procedures have to be planned and executed thoroughly in order to achieve the best functional as well as an optimal aesthetic rehabilitation. On this account a computer-assisted modeling, planning and simulation approach is presented that allows for preoperative assessment of different therapeutic strategies on the basis of three-dimensional patient models. Bone structures can be mobilized and relocated under consideration of anatomical and functional constraints. The resulting facial appearance is simulated via finite-element methods on the basis of a biomechanical tissue model, and visualized using high quality rendering techniques. Such an approach is not only important for preoperative mental preparation, but also for vivid patient information, documentation, quality assurance as well as for surgical education and training.

Maxillofacial surgery simulation using a mass-spring model derived from continuum and the scaled displacement method

“…Studies on linear FE method [18] demonstrate that hexahedra are more accurate than tetrahedra. However, many authors use tetrahedra even when the information to build the model comes from CT scanners given in hexahedra or voxels [2,3,10,13]. Delingette et al [19], for example, favoured the decision of using tetrahedra arguing that it is more difficult to make a meshing with hexahedra (especially in structures with curves) and that it is easier to make cuts over tetrahedra than hexahedra.…”

“…It is well known that living tissues have non homogeneous, anisotropic, non linear, visco-elastic behaviour and that they depend on the history of applied loads [20]. Most simulation models describe this behaviour with linear elastic [2,3,[9][10][11][12]15,16] or non linear elastic models [12,15]. However, the attention paid to some hyperelastic models, such as Money-Rivlin's [15], neo-Hookean models and others [21], is growing.…”

“…Regarding model discretization, the most common elements to fill up 3D models are tetrahedra [2,3,[9][10][11][12][13][14] and hexahedra [11,15,16], though other elements can be used as well [17]. Studies on linear FE method [18] demonstrate that hexahedra are more accurate than tetrahedra.…”

“…It is well known that computer-aided surgical simulation (CASS) is widely used in medicine and it appears to be at least as good as current methods of surgical planning [1]. In the maxillofacial field, for example, surgical simulation is becoming a very powerful tool to plan surgery and simulate surgical results before performing a procedure [2,3].…”

Making Dentition Model from Negative Dental Impression in Implant Treatment

“…Orthodontic surgery corrects congenital or acquired deformations of the skull and face, including maxillofacial deformities, congenital malformations and deformations of the jaw joint. Implant treatment is important in orthodontic surgery, since it enables the replacement of natural teeth (Xia et al, 2000;Xia et al, 2005;Zachow et al, 2006;Swennen et al, 2007). Although the success of technical aspects is important in dental surgery, effective management of the treatment schedule is also essential, since a dentist must consider the intermediate results in determining treatment prognosis.…”