Surgical navigation for implant-supported auricular prosthesis with CAD/CAM technology

Abstract

Patients with deformed or missing ears try to hide their deformities and consequently their quality of life (QoL) may frequently be compromised. Ear reconstruction by means of autogenous or craniofacial implant-supported appliances may serve to improve QoL of this patient group. The hypothesis of the present study was that the use of CAD/CAM and rapid prototyping (RP) technology in the fabrication of implant-supported ear prostheses can improve their treatment outcomes and QoL. The over-all aims of the study were to develop innovative techniques using CAD/CAM and RP technology in the fabrication of implant-supported ear prostheses and provide improvement in the treatment outcomes and QoL of patients. The research project was performed with the aim of achieving innovation and advancement in scientific knowledge through the following approaches:

1. To compare the 3D accuracy of image-guided drillings between Stryker (Nav II iNtellect Cranial, Stryker, Montreux, Switzerland) and BrainLAB (Kolibri Navigation Station 2.0, BrainLAB, Feldkirchen, Germany) Navigation systems and to assess the inter-operator variability. A custom-made acrylic resin block with attached fiducial markers was drilled by three operators to 6mm depth of 10 drill holes guided by each navigation system. On comparison between the two systems, slight under-drilling was common for the Stryker system whereas slight over-drilling was common for BrainLAB. The drill hole deviations assessed in two planes found that more deviation occurred with the Stryker system. Inter-operator variability in drilling angles was more common with the Stryker system whereas BrainLAB was more consistent. In one operator, it appeared that there was a learning curve. 2. To present a new concept of visual axis maintenance in the fabrication of ear prostheses. This was shown in a hemifacial microsomia patient wearing spectacles by using a combination of computer planning and CAD/CAM technology. 3. To present an innovative method of integrating image planning and surgical navigation in performing simulation implant surgery on biomodels and the pre-fabrication of ear prostheses. 4. To evaluate the accuracy of surgical planning and implant installation on biomodels. The method was applied on 6 patients’ biomodels in prefabricating their ear prostheses. The accuracy of the surgical planning and the implant installation on the biomodels was considered having minimal deviation in drill depth, entry point in sagittal position and angulation in coronal and axial planes. 5. To present a new method of implant-supported prosthetic ear fabrication composing of a RP framework simulating the cartilage and covered by different thicknesses of silicone skin. 6. To evaluate the treatment outcomes of prosthetic auricular rehabilitation using surgical navigation in osseointegrated implant installation and prosthetic fabrication with CAD/CAM technology. A clinical series of 6 patients were sequentially recruited for prosthetic ear rehabilitation. It was demonstrated that implant-supported ear prosthesis could induce improvement in their QoL particularly in the domains of the body image, social interaction and mood. The primary insertion torque of the implants was high and hence all cases had achieved immediate implant loading. However, one patient developed persistent adverse periabutment skin response and the implants had to be submerged at this stage.