The use of oral implants in the rehabilitation of partially and fully edentulous patients is widely accepted even though failures do occur. The chance for implants to integrate can for example be jeopardised by the intra-oral presence of bacteria and concomitant inflammatory reactions. The longevity of osseointegrated implants can be compromised by occlusal overload and/or plaque-induced peri-implantitis, depending on the implant geometry and surface characteristics. Animal studies, cross-sectional and longitudinal observations in man, as well as association studies indicate that peri-implantitis is characterised by a microbiota comparable to that of periodontitis (high proportion of anaerobic Gram-negative rods, motile organisms and spirochetes), but this does not necessarily prove a causal relationship. However, in order to prevent such a bacterial shift, the following measures can be considered: periodontal health in the remaining dentition (to prevent bacterial translocation), the avoidance of deepened peri-implant pockets, and the use of a relatively smooth abutment and implant surface. Finally, periodontitis enhancing factors such as smoking and poor oral hygiene also increase the risk for peri-implantitis. Whether the susceptibility for periodontitis is related to that for peri-implantitis may vary according to the implant type and especially its surface topography.

Infectious risks for oral implants: a review of the literature

Physics of Radiology

Cone beam computed tomography (CBCT) has been specifically designed to produce undistorted three-dimensional information of the maxillofacial skeleton, including the teeth and their surrounding tissues with a significantly lower effective radiation dose compared with conventional computed tomography (CT). Periapical disease may be detected sooner using CBCT compared with periapical views and the true size, extent, nature and position of periapical and resorptive lesions can be assessed. Root fractures, root canal anatomy and the nature of the alveolar bone topography around teeth may be assessed. The aim of this paper is to review current literature on the applications and limitations of CBCT in the management of endodontic problems.

https://www.onlinelibrary.wiley.com/doi/pdf/10.1111/j.1365-2591.2008.01531.x

New dimensions in endodontic imaging: part 2. Cone beam computed tomography

Cone Beam Computed Tomography (CBCT) is a diagnostic imaging modality that provides high-quality, accurate three-dimensional (3D) representations of the osseous elements of the maxillofacial skeleton. CBCT systems are available that provide small field of view images at low dose with sufficient spatial resolution for applications in endodontic diagnosis, treatment guidance, and posttreatment evaluation. This article provides a literature review and pictorial demonstration of CBCT as an imaging adjunct for endodontics.

/pdf/use-of-cone-beam-computed-tomography-in-endodontics-2nwthzi1d8.pdf

Use of Cone Beam Computed Tomography in Endodontics

Conebeam x-ray CT (CBCT) is a developing imaging technique designed to provide relatively low-dose high-spatial-resolution visualization of high-contrast structures in the head and neck and other anatomic areas. This first installment in a 2-part review will address the physical principles underlying CBCT imaging as it is used in dedicated head and neck scanners. Concepts related to CBCT acquisition geometry, flat panel detection, and image quality will be explored in detail. Particular emphasis will be placed on technical limitations to low-contrast detectability and radiation dose. Proposed methods of x-ray scatter reduction will also be discussed.

http://www.ajnr.org/content/ajnr/30/6/1088.full.pdf

Conebeam CT of the head and neck, part 1: physical principles.

Purpose There has been a proliferation of available dental x-ray detectors over the recent past. The purpose of this short technical report is to provide a basic comparison of spatial resolution, contrast perceptibility, and relative exposure latitudes of 18 current dental x-ray detectors, including solid-state systems (CCD and CMOS), photostimulable phosphors, and analog film. Methods Spatial resolution was measured using a 0.025 mm Pb phantom test grid with a measurement range from 1.5 to 20 lp/mm. For contrast perceptibility, a 7-mm thick aluminum perceptibility test device with wells of 0.1-0.9 mm depth at 0.1 mm intervals and 1 defect of 1.5 mm was used. The relative exposure latitude was determined by expert consensus using clear discrimination of the enamel-dentin junction as the lower limit and pixel blooming or unacceptable levels of cervical burnout as the upper limit. Results The highest spatial resolution was found with Kodak InSight film, RVG-ui (CCD), and RVG 6000 (CMOS) detectors, each of which achieved 20 lp/mm, followed by the Planmeca Dixi2 v3 at ≥16 lp/mm. Contrast resolution was at least to 0.2 mm through 7 mm aluminum for all 18 detectors, with the best results being found for the Visualix HDI, RVG-ui, RVG 5000, and RVG 6000 detectors and the Schick CDR wired and wireless systems. The greatest exposure ranges were found with photostimulable phosphors and the Kodak RVG 6000 and RVG 5000 detectors. Conclusions Most current x-ray detectors generally perform well in terms of spatial and contrast resolutions, and in terms of exposure latitude. These findings were independent of the modality applied.

A comparison of 18 different x-ray detectors currently used in dentistry

OBJECTIVE To compare the properties of a new speed group F intra-oral X-ray film with those of three well established types both from groups D and E, and evaluate the impact of six commercially available processing solutions. METHODS Four types of dental X-ray film, Flow (Flow X-ray, West Hempstead, NY, USA), speed group F, Ektaspeed Plus (Eastman Kodak, Rochester NY, USA) and M2 Comfort (AgfaGevaert, Morstel, Belgium), both speed group E, and Ultra-speed (Eastman Kodak), speed group D, were exposed under standardised conditions and processed in six different processing solutions. Base plus fog density, characteristic curves, film density, speed, average gradient, contrast and latitude and spatial resolution were calculated. RESULTS The choice of processing chemistry affected radiographic characteristics including speed grouping. The new F film was consistently the fastest. M2 Comfort could achieve F speed and Ultra-speed achieved E speed using Automat XR chemicals. The speed of Ektaspeed Plus was indepen...

Evaluation of a new F speed dental X-ray film. The effect of processing solutions and a comparison with D and E speed films.

OBJECTIVE To examine the feasibility of substituting observers determining the accuracy of endodontic measurements for measurements of physical qualities in comparison of digital imaging systems. METHODS Sensors from six digital imaging systems were compared for signal-to-noise ratio (SNR), modulation transfer function (MTF) and detective quantum efficiency (DQE). A total of 45 canals in teeth from human cadavers were instrumented to their apical foramina. Endodontic files, ranging in size from size 8 to size 20, were glued in place at random distances from the apical foramina spanning a range of +/- 3 mm. The teeth were imaged with the six digital systems and dental X-ray film. Fifteen dentists independently measured the distance from the end of the file to the apical foramen. Results were expressed as the measurement error. Measurement error was compared to SNR, MTF and DQE for each digital system. RESULTS CDR (Schick, New York, NY, USA), Digora (Sordex, Helsinki, Finland) and Dexis (Provision Dental Sy...

Comparison of observer performance in determining the position of endodontic files with physical measures in the evaluation of dental X-ray imaging systems.

Accurate assessment of intraosseous lesion dimensions is useful in determining strategies for treatment of periradicular pathoses of dental causation. Objectives. To compare the efficacy of digital versus analog imaging for the measurement of mesiodistal and vertical dimensions of periapical lesions in patients that require apical surgery. Methods: Fourteen examiners assessed the dimensions of 28 lesions with a millimeter ruler and Ektaspeed Plus radiographs (Eastman Kodak, Rochester, N.Y.), and with the Visualix-2 (Gendex/Dentsply, Milan, Italy) in unenhanced, contrast-stretched and equalized modes with proprietary software mouse-driven measurement algorithm. Impregum F (Premier Dental Products) impressions at surgery were used as the “gold standard.” Ten randomly chosen images were reread 2 weeks later to assess intra-operator reliability. As the Mauchly sphericity test was significant for all tests, a multivariate analysis of variance was used to assess accuracy. To explain the exact difference between means, the Bonferroni test was applied. Intra-observer reliability was assessed with Friedman's two-way analysis of variance; inter-observer effects were determined with Cronbach's alpha. Results. For accuracy in measurement, the closest to the “gold standard” were achieved with the Visualix-2 with image equalization. The contrast-stretched Visualix-2 and unenhanced Visualix-2 measurements were less accurate; conventional film was consistently the least accurate (p Conclusions. Charge-coupled device-based images with the Visualix-2 are preferable to film-based radiographs for measuring periapical lesion dimensions.

In vivo comparison of Visualix-2 and Ektaspeed Plus in the assessment of periradicular lesion dimensions

Density versus exposure was determined for digital and film radiographic images of various thicknesses of six dental resin composites. The curves were relatively parallel; saturation at the black end of the contrast scale occurred at lower exposures with Computed Dental Radiography (CDR, Schick Industries, Long Island City, NY) than with the Sens-A-Ray (Regam AB, Sundsvall, Sweden). Ektaspeed Plus film (Kodak Dental Products, Rochester, NY) was the least sensitive modality tested. The DIGORA storage phosphor system (Soredex-Orion, Helsinki) had a wide exposure latitude with significantly less steep characteristic slopes than for images from the charge-coupled devices (CCDs). Slopes generated for the Sens-A-Ray and the CDR were not significantly different. Slopes generated for each resin composite were not significantly different for each of the modalities. Relative radiopacities of the resin materials with respect to each other were constant across all modalities; hence, in these systems, sensor type is unlikely to affect differentiation between resin composites and dental enamel or recurrent caries.

Taeko T. Farman

Papers

A comparison of 18 different x-ray detectors currently used in dentistry

Evaluation of a new F speed dental X-ray film. The effect of processing solutions and a comparison with D and E speed films.

Comparison of observer performance in determining the position of endodontic files with physical measures in the evaluation of dental X-ray imaging systems.

In vivo comparison of Visualix-2 and Ektaspeed Plus in the assessment of periradicular lesion dimensions

Optical densities of dental resin composites: a comparison of CCD, storage phosphor, and Ektaspeed plus radiographic film.