Peter Y. P. Wat

Proximal Contact loss between Implant-Supported Prostheses and Adjacent Natural Teeth: A Clinical Report

There is limited knowledge about the changes that proximal contacts between implant-supported prostheses and adjacent teeth undergo over time. This report describes the management of a clinical situation with the loss of proximal contact between implant-supported prostheses and adjacent natural teeth in a partially edentulous patient.

Rehabilitation of a mandibulotomy/onlay/graft-reconstructed mandible using a milled bar and a tooth- and implant-supported removable dental prosthesis: A clinical report

Prosthodontic rehabilitation of a surgically resected/reconstructed jaw with a conventional tissue-borne dental prosthesis is often challenging, if not impossible, because of the suboptimal conditions of the soft and hard tissue topography/architecture of the reconstructed site. Placing dental implants in grafted bone to provide appropriate support, stability, and retention for prosthodontic rehabilitation offers the potential for improved oral function. There are, however, some clinical conditions for which an implant-supported removable prosthesis may be preferred to a fixed implant prosthesis. This clinical report describes the design and fabrication of a milled bar and a tooth- and implant-supported removable dental prosthesis for oral rehabilitation of a reconstructed mandible, which considers patient factors associated with oral and financial conditions, ease of oral hygiene procedures, and long-term maintenance.

Retrievable cement-retained implant-tooth-supported prosthesis: a new technique.

Clinicians often encounter difficulties with connecting natural teeth and osseointegrated implants. A new clinical technique with laboratory procedures are presented. The technique involves cementation of a two-part prosthesis over natural teeth and customized implant gold cylinders. This method achieved a passive-fit fixed bridge with retrievability maintained.

Image calibration and registration in cone-beam computed tomogram for measuring the accuracy of computer-aided implant surgery

Medical radiography is the use of radiation to “see through” a human body without breaching its integrity (surface). With computed tomography (CT)/cone beam computed tomography (CBCT), three-dimensional (3D) imaging can be produced. These imagings not only facilitate disease diagnosis but also enable computer-aided surgical planning/navigation. In dentistry, the common method for transfer of the virtual surgical planning to the patient (reality) is the use of surgical stent either with a preloaded planning (static) like a channel or a real time surgical navigation (dynamic) after registration with fiducial markers (RF). This paper describes using the corner of a cube as a radiopaque fiducial marker on an acrylic (plastic) stent, this RF allows robust calibration and registration of Cartesian (x, y, z)- coordinates for linking up the patient (reality) and the imaging (virtuality) and hence the surgical planning can be transferred in either static or dynamic way. The accuracy of computer-aided implant surgery was measured with reference to coordinates. In our preliminary model surgery, a dental implant was planned virtually and placed with preloaded surgical guide. The deviation of the placed implant apex from the planning was x=+0.56mm [more right], y=- 0.05mm [deeper], z=-0.26mm [more lingual]) which was within clinically 2mm safety range. For comparison with the virtual planning, the physically placed implant was CT/CBCT scanned and errors may be introduced. The difference of the actual implant apex to the virtual apex was x=0.00mm, y=+0.21mm [shallower], z=-1.35mm [more lingual] and this should be brought in mind when interpret the results.

Novel geometric coordination registration in cone-beam computed Tomogram

The use of cone-beam computed tomography (CBCT) in medical field can help the clinicians to visualize the hard tissues in head and neck region via a cylindrical field of view (FOV). The images are usually presented with reconstructed three-dimensional (3D) imaging and its orthogonal (x-, y- and z-planes) images. Spatial relationship of the structures in these orthogonal views is important for diagnosis of diseases as well as planning for treatment. However, the non-standardized positioning of the object during the CBCT data acquisition often induces errors in measurement since orthogonal images cut at different planes might look similar. In order to solve the problem, this paper proposes an effective mapping from the Cartesian coordinates of a cube physically to its respective coordinates in 3D imaging. Therefore, the object (real physical domain) and the imaging (computerized virtual domain) can be linked up and registered. In this way, the geometric coordination of the object/imaging can be defined and its orthogonal images would be fixed on defined planes. The images can then be measured with vector information and serial imagings can also be directly compared.