Dental Imaging System Research Articles

Tissue mimicking materials for dental ultrasound

While acoustic tissue mimicking materials have been explored for a variety of soft and hard biological tissues, no dental hard tissue mimicking materials have been characterized. Tooth phantoms are necessary to better understand acoustic phenomenology within the tooth environment and to accelerate the advancement of dental ultrasound imaging systems. In this study, soda lime glass and dental composite were explored as surrogates for human enamel and dentin, respectively, in terms of compressional velocity, attenuation, and acoustic impedance. The results suggest that a tooth phantom consisting of glass and composite can effectively mimic the acoustic behavior of a natural human tooth.

Digital Subtraction Technique for Evaluation of Peri-Implant Bone Change in Digital Dental Imaging

The purpose of this study was to investigate digital subtraction technique in digital dental imaging for implant performance, used to quantitatively evaluate bone change around dental implants. For longitudinal assessment of peri-implant bone change, we applied subtraction technique to digital peri-apical radiographs using a digital dental imaging system in two cases at the upper canine and premolar regions. In both cases, we found two peaks of bone change at the crestal region; we also quantitatively demonstrated a marked change over the first one-month period and approximately three-month period spanning the fourth month to the end of the sixth month following implantation. Digital peri-apical radiography accommodating the digital subtraction program should be re-acknowledged as a reliable modality for assessing amount of bone change at local implantation sites.

Three-dimensional localization of maxillary canines with cone-beam computed tomography

Precise 3-dimensional (3D) localization of impacted canines is central to their clinical management. Recently introduced dental 3D volumetric imaging systems make precise localization possible. The purpose of this study was to describe the spatial relationship of impacted canines by using images obtained with the NewTom QR-DVT 9000 (QR Srl, Verona, Italy). Unilaterally and bilaterally impacted canines (n = 27) from 19 consecutive patients (15 female, 4 male) were evaluated on images taken with the NewTom QR-DVT 9000. The spatial relationships of the impacted canines relative to adjacent structures and incisor resorption were assessed with 3D visualization software. Most (92.6%) of the 27 impactions were palatal. Incisor resorption adjacent to the impacted canine was present in 66.7% of the lateral incisors and 11.1% of the central incisors. Follicle size did not play a major role in influencing impacted canine position. The alveolus was narrower at the impacted canine side compared with the erupted canine side; however, the width of the alveolus on the impacted canine side is independent of the deciduous canines. A correlation was found between the proximity of the impacted canine to the incisors and their resorption. There was no common location where eruption was arrested, and great variation in the inclination of the impacted canine was found. 3D volumetric imaging of impacted canines can show the following: presence or absence of the canine, size of the follicle, inclination of the long axis of the tooth, relative buccal and palatal positions, amount of the bone covering the tooth, 3D proximity and resorption of roots of adjacent teeth, condition of adjacent teeth, local anatomic considerations, and overall stage of dental development. In short, 3D imaging is clearly advantageous in the management of impacted canines.

Third-molar impaction diagnostic with cone-beam computerized tomography

Precise three-dimensional localization of impacted third molars as it relates to the inferior dental canal (IDC) is critical to their clinical management and highly influences surgical outcomes. Recently introduced dental 3D volumetric imaging systems coupled with semi-automatic modelling techniques allows 3D visualization of the IDC and the third molar. In this study, the spatial relationship of impacted third molars is described using imaging data obtained from various 3D volumetric imaging systems (NewTom 9000, Morita Accuitomo and Hitachi Mercuray).

Storage Phosphor Plates: How Durable are they as a Digital Dental Radiographic System?

The aim of this in vitro investigation was to evaluate the durability of storage phosphor plates (SPPs) as a digital dental imaging system and to detect the factors that may contribute to possible reduced durability. A total of 140 new SPPs were divided into groups and exposed to the effects of the various handling steps during the image acquisition. An additional group of plates joined the existing plates in the Radiology Clinic and tested the additive effect of all these factors plus the effect of positioning the plates in a patient's mouth. The images resulting from these SPPs were regularly evaluated for the appearance of scratches as a sign of wear and rated by an oral radiologist using a 6 point scale. Although the manufacturer claims the SPPs can be used indefinitely, we found 95% of our plates were rendered non-diagnostic after only 50 uses. The manufacturer's claim for indefinite use of the SPPs seems to be questionable.

Is linear response to x-rays suitable for digital dental x-ray imaging systems? —Theoretical and experimental considerations

Objectives The purpose of this study was to consider theoretically and experimentally the suitability of linear response to x-rays for digital dental x-ray imaging systems.

An integrating CMOS APS for X-ray imaging with an in-pixel preamplifier

We present in this paper an integrating CMOS Active Pixel Sensor (APS) circuit coated with scintillator type sensors for intra-oral dental X-ray imaging systems. The photosensing element in the pixel is formed by the p-diffusion on the n-well diode. The advantage of this photosensor is its very low direct absorption of X-rays compared to the other available photosensing elements in the CMOS pixel. The pixel features an integrating capacitor in the feedback loop of a preamplifier of a finite gain in order to increase the optical sensitivity. To verify the effectiveness of this in-pixel preamplification, a prototype 32×80 element CMOS active pixel array was implemented in a 0.8 μm CMOS double poly, n-well process with a pixel pitch of 50 μm. Measured results confirmed the improved optical sensitivity performance of the APS. Various measurements on device performance are presented.

A CMOS APS for dental X-ray imaging using scintillating sensors

In this paper we present an integrating CMOS Active Pixel Sensor (APS) circuit to be used with scintillator type X-ray sensors for intra oral dental X-ray imaging systems. Different pixel architectures were constructed to explore their performance characteristics and to study the feasibility of the development of such systems using the CMOS technology. A prototype 64×80 pixel array has been implemented in a CMOS 0.8 μm double poly n-well process with a pixel pitch of 50 μm. A spectral sensitivity measurement for the different pixels topologies, as well as measured X-ray direct absorption in the different APSs are presented. A measurement of the output signal showed a good linearity over a wide dynamic range. This chip showed that the very low sensitivity of the CMOS APSs to direct X-ray exposure adds a great advantage to the various CMOS advantages over CCD-based imaging systems.

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

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

Image contrast range for detection of enamel defects using a digital dental imaging system

The purpose of this study was to quantitatively assess the acceptable range of image contrast for the detection of enamel defects by adjusting the contrast and brightness of a digital dental imaging system. Extracted human premolars and molars with enamel defects on the proximal surfaces were mounted in maxillary and mandibular sets on phantoms. The phantoms were individually exposed and processed with a digital dental imaging system from Computed Dental Radiography (CDR, Schick Technologies, Inc., NY, USA). The images were transferred to a personal computer, and the contrast and brightness were determined in the range of ±100 digital digit numbers (DDN) using Adobe Photoshop 4.0.1 J (Adobe Systems Inc., Tokyo, Japan). The 8-bit CRT display used was set at maximum inherent brightness. The relationship between the pixel value and the DDN in contrast at both the enamel and the background on the monitor was used to measure the acceptable image contrast by manipulating contrast and brightness. Six dental radiologists were asked to determine the presence or absence of enamel defects. The detectability was statistically analyzed using Fisher's protected limited standard deviation (PLSD) non-parametric test. When the inherent brightness on an 8-bit CRT display was adjusted to the maximum, there was an acceptable range of image contrast and brightness for the detection of enamel defects with this digital dental imaging system.

Influence of X-ray beam angulation in the detection of proximal caries: Interobserver agreement in the CCD system

The aim of this study was to assess the influence of changes in horizontal and vertical X-ray beam angulation on interobserver agreement in the diagnosis of approximal caries using a charge coupled device-based digital dental imaging system (digital system) in comparison with a conventional film-based radiography (film system).

Consideration for Density Optimization and Dose Reduction of Digital Dental Imaging System Using Fuzzy C-Means Clustering

Consideration for Density Optimization and Dose Reduction of Digital Dental Imaging System Using Fuzzy C-Means Clustering

Computed dental radiography system versus conventional dental X-ray films for detection of simulated proximal caries

The diagnostic accuracy of intraoral images obtained with a first generation Computed Dental Radiography (CDR) digital dental imaging system is compared with the diagnostic accuracy of conventional dental x-ray film images using a receiver operating characteristics (ROC) analysis. Fifteen dentition phantoms were constructed. Each contained 4 teeth, consisting of premolar and molar teeth with 6 proximal surfaces. Mechanical defects were created randomly on the proximal surfaces and plugged with dentine powder to simulate caries. Fifteen images of each modality were rated by nine dentists in separate sessions according to their confidence in their ability to detect the simulated caries. The images examined were as follows: original CDR images, CDR images magnified 2×, CDR images magnified 4 ×, Ektaspeed Plus dental x-ray film images, and Ultraspeed dental x-ray film images, both unmagnified and magnified 2 ×. A series of ROC curves indicated the limited usefulness of magnification for the CDR system, and consistently similar success in detecting simulated proximal caries for original CDR images and original film images. The magnification of original film images did not always promote greater success than that obtained with the original film images.

Radiovisiographic Diagnosis of Dental Caries: Initial Comparison of Basic Mode Videoprints with Bitewing Radiography

Radiovisiography (RVG) is a commercially available, dental radiographic digital imaging system which is claimed to rival conventional techniques in terms of decreased radiation dose and the production of instantaneous images. The aim of this study was to compare in vitro the sensitivities and specificities derived from three examiners using conventional bitewing radiographic film (D and E speed) with those achieved by the same examiners using basic mode RVG bitewing videoprints of occlusal and approximal caries. Videoprints were used in this study, as they are the principal method of archiving radiovisiographic images, unless a separate compatible personal computer is used. The histological appearance of the subsequently sectioned teeth was used as the validating criterion. The in vitro results of basic mode RVG suggest that for occlusal caries, overall the sensitivity and specificity of RVG videoprints are similar to those of bitewing radiography. For approximal caries, the specificity of RVG videoprints was similar to that of bitewing radiography, but the sensitivity was slightly lower. Further work using the different modes available and electronically modified images is indicated.

Quantitative assessment of a new dental imaging system

The "Radiovisiography" dental imaging unit (Trophy UK Ltd) is a digital system using an intensifying screen and charge-coupled device in an intra-oral sensor. This paper presents a description of the system and an assessment of the original model in terms of patient dose (relative to film systems), resolution (limiting resolution and modulation transfer function), distortion and image noise (amplitude). The system does offer the possibility of reduced patient exposure and minimal distortion, although resolution and latitude are inferior to standard dental film.

Quantitative evaluation of digital dental radiograph imaging systems

Two digital imaging systems, a video camera and analog-to-digital converter, and a charge-coupled device linear photodiode array slide scanner, were tested for their suitability in quantitative studies of periodontal disease. The information content in the original films was estimated, and digital systems were assessed according to these requirements. Radiometric and geometric performance criteria for the digital systems were estimated from measurements and observations. The scanner-based image acquisition (digitization) system had no detectable noise and had a modulation transfer function curve superior to that of the video-based system. The scanner-based system was equivalent to the video-based system in recording radiographic film densities and had more geometric distortion than the video-based system. The comparison demonstrated the superiority of the charge-coupled device linear array system for the quantification of periodontal disease extent and activity.

Radiovisiography: an initial evaluation

An initial evaluation of the latest dental radiographic imaging system, radiovisiography, is reported. Despite limitations in its possible clinical applications and problems inherent within the system design, radiovisiography has been found to be a rapid imaging system capable of producing clinically acceptable periapical images. It is suggested that this system may be of particular value in endodontics and in its present form should be considered as an adjunct rather than as a replacement for conventional intra-oral film. Further studies are now required into recent system modifications which are described.

Dental xeroradiography as an adjunct in the evaluation of oral cancer: A preliminary report

This pilot study of an experimental dental xeroradiography imaging system involved twelve oral cancer clinic patients. Xeroradiographs were compared with conventional intraoral film radiographs, taken with similar x-ray projections. The new dental xeroradiographic system was judged superior for the imaging of both osseous and soft-tissue structures. Especially significant was the new imaging system's ability to portray early bone erosion not detectable with the conventional intraoral film technique. These results point to the need for controlled clinical evaluations of dental xeroradiography, in order to assess the full potential of this rapid, low-radiation imaging system in the evaluation of oral cancer.