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The aim of this study was to (1) evaluate the fractal dimension (FD) in regions of the mandible on cone beam CT (CBCT) images of patients with bisphosphonate-associated osteonecrosis of the jaws (BP-ONJ) and (2) to select the most suitable region of interest (ROI) for further study on detection of bone alterations associated with bisphosphonates.CBCT images of patients with BP-ONJ were included with matched controls. Values of FD were compared between groups. Selected ROIs were: ROI-1 - below the mandibular foramen; ROI-2 - above the mandibular foramen; ROI-3 - anterior to the mental foramen; ROI-4 - above the mandibular canal. The area of bone exposure was included as ROI-5. The results were analysed using generalized estimating equations and conditional logistic regression.There were 36 patients (67% female) with a mean age of 60.7 years. The mean FDs were: ROI-1 - 1.678 for controls and 1.673 for patients (P = 0.81); ROI-2 - 1.657 for controls and 1.653 for patients (P = 0.78); ROI-3 - 1.661 for controls and 1.684 for patients (P = 0.17); and ROI-4 - 1.670 for controls and 1.698 for patients (P = 0.03). The value of the FD in the area of exposed bone was the highest (1.729). The odds of being a BP-ONJ patient vs being a control was six times as high for individuals with a higher FD score at ROI-4, although the confidence interval was quite wide owing to the small sample size.In this preliminary study, BP-ONJ patients had higher FD values than controls at regions close to the alveolar process. The results suggest that FD is a promising tool for detection of bone alterations associated with BP-ONJ.

To evaluate experimentally how in direct digital radiography heterogenous detector response may influence the depiction of small mass differences.A step wedge of a bone-simulating resin was imaged at 70 kVp using RadioVisioGraphy ZHR 32000. Exposure time and step wedge position on the detector varied. The pixel values of the stored images of the step wedge were converted to luminance values of the displayed images.The relationship between pixel and luminance values was non-linear. The difference in luminance between adjacent steps varied with position of step wedge. Regardless of position, there was an increase in difference of luminance between steps with increasing exposure. A greater relative change in luminance was consequently seen in the thinner parts of the step wedge. The failure to perceive individual steps of the wedge in its thicker parts was related to insufficient relative change in luminance between steps.The heterogeneous response of the detector resulted in a varying ability to depict small mass changes over the detector area.

Intraoral radiographs occasionally disclose radiopaque zones in the dentine adjacent to amalgam fillings. Usually, they extend from the filling material towards the pulp cavity and tend to follow the direction of the dentinal tubules thereby creating a funnel-shaped appearance. It has been proved by VAN DER LINDEN and VAN AKEN (5) that such alterations are associated with an uptake in the dentine of mostly zinc and tin originating from the filling material. Another interesting observation made by the same authors was that the dentine close to the filling in the majority of the cases was carious. In a study on initial stages of secondary caries HALS and HALSE (1) found that microradiographs may show a narrow zone with high radiopacity close to amalgam fillings. Electron probe analysis showed that these zones contained relatively large amounts of zinc and tin. It seems justified to assume that the metals penetrate through the dentinal tubules (2). In another microradiographic investigation HALSE and HALS (3) found an increased radiopacity in the dentine close to silicate fillings. Although the electron probe analysis disclosed penetration into the dentine of zinc and aluminium the distribution of these metals did not correspond to the extension of the radiopaque zones in the microradiographs. These investigations raise several questions, especially concerning the reactions in the dentine and the pulp. The present study aimed at elucidating: . 1. can radiopaque zones be found also adjacent to silicate fillings? 2. how frequently are such lesions seen on intraoral radiographs? 3. how often are they associated with radiographically demonstrable caries?

Xeroradiographs and Kodak Ektaspeed film were compared with Kodak Ultraspeed film for their ability to reveal calculus deposits. Jaw specimens from cadavers having root surfaces that were either free of calculus or had calculus deposits were used as test objects. The specimens were first radiographed using xeroradiographic plates or radiographic film as the image receptors. Following radiography of the specimens, the actual presence of calculus was determined by direct inspection and probing with an explorer. Thirteen oral radiologists scored the xeroradiographic and film images for the presence of calculus on the 25 selected mesial or distal surfaces. The results showed that dentists detected 55 to 60% of the calculus deposits while at the same time they considered calculus to be present on 10 to 28% of the calculus-free surfaces. ROC analysis of the radiographic decisions showed no significant difference in the diagnostic performance of the dentists using xeroradiographic images, Ektaspeed film, or Ultr...

It has long been known that the radiographic examination in disorders of the temporomandibular joint (TMJ) has several inherent sources of error. It has thus been shown, among other things, that the relationship between the various parts of the TMJ is apt to vary with the diagnostic method used (10, 11, 12, 13, 16, 17, 18). It has also been shown that the conception of the shape and structure of the various components of the joint varies with the examination method used (6, 7, 9, 11). Despite these drawbacks radiographic examination of the TMJ is widely accepted and used in all parts of the world, especially in the examination of patients with symptoms referable to the region of the TMJ as well as in the planning of treatment and the follow-up of the therapeutic effect of rehabilitation. It is remarkable, however, that the projection most widely used all over the world i. e. the oblique transcranial projection, is unreliable from a diagnostic point of view (4, 10, 11, 12, ]6, 18).