Spiral computed tomography based maxillary sinus imaging in relation to tooth loss, implant placement and potential grafting procedure.

Objectives: The purpose of the present study was to explore the maxillary sinus anatomy, its variations and volume in patients with a need for maxillary implant placement.

Material And Methods: Maxillary sinus data of 101 consecutive patients who underwent spiral computed tomography (CT) scans for preoperative implant planning in the maxilla at the Department of Periodontology, University Hospital, Catholic University of Leuven, Leuven, Belgium were retrospectively evaluated. The alveolar bone height was measured on serial cross-sectional images between alveolar crest and sinus floor, parallel to the tooth axis.

Computer-aided detection of colonic polyps using low-dose CT acquisitions.

Rationale And Objectives: This report proposes an alternative method for the automatic detection of colonic polyps that is robust enough to be directly applicable on low-dose computed tomographic data.

Materials And Methods: The polyp modeling process takes into account both the gray-level appearance of polyps (intensity profiles) and their geometry (extended Gaussian images). Spherical harmonic decompositions are used for comparison purposes, allowing fast estimation of the similarity between a candidate and a set of previously computed models.

Computer aided detection for low-dose CT colonography.

The paper describes a method for automatic detection of colonic polyps, robust enough to be directly applied to low-dose CT colonographic datasets. Polyps are modeled using gray level intensity profiles and extended Gaussian images. Spherical harmonic decompositions ensure an easy comparison between a polyp candidate and a set of polypoid models, found in a previously built database.

Radiation dose vs. image quality for low-dose CT protocols of the head for maxillofacial surgery and oral implant planning.

The goal of this study was to determine the acquisition parameters for a low-dose multi-slice CT protocol and to compare the effective dose and the image quality of this low-dose protocol with the image quality of a clinical multi-slice CT protocol, routinely used for visualisation of the head. The low-dose protocol was derived from a clinical multi-slice CT protocol by lowering mA s and kV and increasing the pitch. The low-dose protocol yielded a dose reduction from 1.

The nasopalatine canal revisited using 2D and 3D CT imaging.

Objectives: To assess the location, morphology and dimensions of the nasopalatine canal on two-dimensional and three-dimensional (2D and 3D) CT images.

Methods: Material included 34 spiral CT scans for pre-operative planning of implant placement in the maxilla. Scanning was performed using a standard exposure and patient positioning protocol.

Age calculation using X-ray microfocus computed tomographical scanning of teeth: a pilot study.

To correlate dental age with an individual's chronological age based on the calculated volume ratio of pulp versus tooth volume measured, an X-ray microfocus computed tomography unit (microCT) with 25 microm spatial resolution was used to non-destructively scan 43 extracted single root teeth of 25 individuals with well-known chronological age. Custom-made analysis software was used by two examiners to obtain numerical values for pulpal and tooth volume. The ratio of both was calculated and statistically processed.

Progressive versus constant tapered shaft design using NiTi rotary instruments.

Aim: To evaluate the influence of a progressive versus constant tapered shaft design on canal preparation by NiTi rotary techniques.

Methodology: A XMCT-scanner and custom-made software were used to nondestructively analyse the mesial canals of 10 extracted mandibular molars in 3D with a spatial resolution of 12.5 microm.

[Bone distraction osteogenesis].

Bone osteogenesis has been used by many surgeons to compensate dissymmetry due to congenital malformations, diseases or traumas. Bone distraction is the process of generating new bone in a gap between two bone segments in response to the application of graduated tensile stress across the bone gap. Different types of distraction are actually proposed to be an alternative to facial osteotomies or bone grafting techniques.

Accuracy of drilling guides for transfer from three-dimensional CT-based planning to placement of zygoma implants in human cadavers.

The accuracy of surgical drilling guides was assessed for placement of zygoma implants. Six zygoma fixtures of length 45 mm (Nobel Biocare, Göteborg, Sweden) were placed in three formalin-fixed human cadavers using surgical drilling guides. The fabrication of these custom-made drilling guides was based on three-dimensional computerized tomography (3D-CT) data for the maxillary-zygomatic complex.

Smooth flexible versus active tapered shaft design using NiTi rotary instruments.

Aim: The aim of this study was to evaluate the influence of a smooth flexible versus active tapered shaft design on canal preparation by NiTi rotary techniques.

Methodology: A XMCT-scanner (SkyScan 1072) and developed software (Bergmans et al. 2001) were used to nondestructively analyze the mesial canals of 10 extracted mandibular molars in 3D with a spatial resolution of 30 microm.

A custom template and definitive prosthesis allowing immediate implant loading in the maxilla: a clinical report.

Purpose: The purpose of the present investigation was to examine to what extent precision data from 3-dimensional planning software for oral implants can be transferred to the operative field by means of a drilling template, containing high-precision drilling sleeves, fitted on the jawbone. It was investigated whether this procedure would allow advance preparation of a fixed definitive prosthesis that could be placed at the completion of surgery.

Materials And Methods: This procedure was experimentally carried out in 2 cadavers and later in 8 consecutive human patients.

Cervical external root resorption in vital teeth.

External resorptions associated with inflammation in marginal tissues present a difficult clinical situation. Many times, lesions are misdiagnosed and confused with caries and internal resorptions. As a result inappropriate treatment is often initiated.

Image-based planning and validation of C1-C2 transarticular screw fixation using personalized drill guides.

Objective: Posterior transarticular spine fusion is a surgical procedure used to stabilize the cervical bodies C1 and C2. Currently, spine screws are used most frequently, according to the procedure of Magerl. As the anatomy is rather complex and the view is limited, this procedure has a high risk factor.

Computer-aided diagnosis in virtual colonography via combination of surface normal and sphere fitting methods.

The success of CT colonography (CTC) depends on appropriate tools for quick and accurate diagnostic reading. Current advancements in computer technology have the potential to bring such tools even to personal computer level. In this paper a technique for computed-aided diagnosis (CAD) using CT colonography is described.

Mechanical root canal preparation with NiTi rotary instruments: rationale, performance and safety. Status report for the American Journal of Dentistry.

The growing use of NiTi rotary instruments in dental practice demands a good understanding of their concept of alloy and design in relation to improved properties and inherent limitations. Nickel titanium's super elasticity allows more centered canal preparations with less transportation and a decreased incidence of canal aberrations. Furthermore, the production of files with increased taper became possible.

A methodology for quantitative evaluation of root canal instrumentation using microcomputed tomography.

Aim: The aim of this paper was to present an objective methodology for quantitative evaluation of root canal instrumentation using microcomputer tomography, together with developed software based on a constructed mathematical model.

Methodology: A desktop X-ray micro-CT scanner (SkyScan 1072) was used to provide data sets of an extracted mandibular molar before and after instrumentation (ProFile 0.04 Taper instruments, Dentsply Maillefer, Ballaigues, Switzerland) that were stored for later use by software.

An image-based 3D planning environment for hemicricolaryngectomy and reconstruction by tracheal autotransplantation.

Objective: A new conservation method for unilateral glottal cancer with significant subglottal extension consists of a hemicricolaryngectomy and subsequent reconstruction of the laryngeal defect with a transferable patch of revascularized cervical trachea. In order to restore the three crucial functions of the larynx - airway patency, speech, and swallowing--the reconstructed larynx should resemble a situation with one paralyzed and one intact vocal fold at the glottal level. We hypothesize that this result can be achieved when the tracheal patch meets a typical surgical constraint--the so-called paramedian position at the glottal level - and when the patch is rigidly applied.

Three-dimensional imaging of acetabular dysplasia: diagnostic value and impact on surgical type classification.

Objective: To investigate the diagnostic value and the impact on surgical type classification of three-dimensional (3D) images for pre-surgical evaluation of dysplastic hips.

Materials And Methods: Three children with a different surgical type of hip dysplasia were investigated with helical computed tomography. For each patient, two-dimensional (2D) images, 3D, and a stereolithographic model of the dysplastic hip were generated.

An image-guided planning system for endosseous oral implants.

A preoperative planning system for oral implant surgery was developed which takes as input computed tomographies (CT's) of the jaws. Two-dimensional (2-D) reslices of these axial CT slices orthogonal to a curve following the jaw arch are computed and shown together with three-dimensional (3-D) surface rendered models of the bone and computer-aided design (CAD)-like implant models. A technique is developed for scanning and visualizing an eventual existing removable prosthesis together with the bone structures.

Using WWW and JAVA for image access and interactive viewing in an integrated PACS.

We start from the observations that (1) potential benefits from PACS can only be realized if PACS and HIS are integrated into a 'multimedia medical information system', and (2) that this also requires integration at the level of the user interface. The user interface should allow integrated interaction with information from different subsystems, of which PACS is one. However, in the real world, different information systems are constructed using different technologies.

Computer-assisted planning of oral implant surgery: a three-dimensional approach.

A planning system for oral implant surgery based on a true three-dimensional approach is described. This system allows the interactive placement and adjustment of axial-symmetric models representing implants in the jawbone structures visible on computerized tomographic volume data. Simultaneous visualization is possible on two-dimensional reformatted images and on three-dimensional-derived bone surface representations.

Computer-assisted planning of oral implant surgery. An approach using virtual reality.

A planning system for oral implant surgery is described. This system allows the interactive placement and adjustment of models representing oral implants on CT volume data. These CT data can be shown as two-dimensional (2D) slices, or as a three-dimensional (3D) surface-rendered model.

A semiautomatic three-dimensional segmentation method for disarticulation of bone structures on spiral computed tomography images.

The use of binary thresholding for segmenting bone structures on spiral computed tomography images is negatively influenced by partial volume effects (PVEs) induced by the image acquisition. PVE leads to mixed voxels, making the binary decision "bone" or "nonbone" a difficult one to take. As a result, two distinct bone structures that are close to each other will often appear to be connected by this method.

[Three-dimensional imaging of acetabular fractures using spiral CT].

Seven adult patients with acetabular fractures were investigated with conventional X-rays, axial spiral computed tomographic (CT) images and three-dimensional (3D) surface rendered reconstructions. Spiral CT has the advantage that it acquires the data much faster than incremental CT, resulting in less motion artefacts. A semi-automatic three-dimensional environment for segmentation has been developed in our institution.

[Clinical application of three-dimensional spiral CT in skeletal disorders].

Three-dimensional (3D) computed tomographic reformations are used as an adjunct to standard axial computed tomography (CT) in the evaluation of disorders affecting areas of complex anatomy such as the skull, the spine, the pelvis, hands and feet. 3D-CT can provide a clear impression of lesion extent, pattern, shape and proximity to adjacent structures. This unique spatial information potentially has a significant impact on decisions regarding resectability, surgical approach and repair.