Densitometric analysis of lower molar interradicular areas in superposable radiographs

Abstract

Superposable radiographs of lower molar areas were obtained by means of a specially designed film holder and a gnathostat maintained in a constant position with respect to long-cone radiological equipement. A quantitative evaluation of the bone mass in the interradicular area was obtained by scanning the area under a photodensitometer. A photodensitometric scan of the image of an aluminium wedge adapted to each radiograph was also performed. This allowed the transformation, with the aid of a computer, of the photodensitometric recording of bone into a tracing of mm of aluminium equivalents. The reproducibility and precision of the method were verified by comparing magnifications of repeated radiographs, by photodensitometric readings of radiographs developed in different batches and by repeated quantitative readings of the same film. The method allowed one, for instance, to follow quantitatively the healing of a radiographically visible periapical lesion. It was also used to evaluate quantitatively, in the interradicular area, bone changes which could not be seen with the marked eye.

Influence of overlying soft tissues on radiographic absorptiometry in intraoral radiography

“…1,2,14 Using digitization of video images, Iwashita et al 14 reported that the Al-eq values of dried mandible are approximately 6 mm for the alveolar bone between the first and second premolars and 8 mm between the first and second molars. Duinkerke et al 15 used an optical densitometer and obtained values for alveolar bone in the dried mandible that were almost equal to those reported by Iwashita et al 14 In an in vivo study, Payot et al 8 found that a densitometer scanning profile gave an Al-eq value of approximately 6 mm at the bifurcation area without bone loss at the mandibular first molar. The results of the present study revealed that the inaccuracies of Al-eq values were approximately 1 mm in the area corresponding to the bifurcation and approximately 2 mm in the periapical area on the plane situated at the contact point between the first and second molars (Table 1).…”

“…[1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17] However, soft tissue can influence the measurement of mandibular bone density. 7 Under the assumption that the thickness of buccal soft tissue either does not change or changes only negligibly, a calibration curve obtained with a reference wedge can be applied to the entire area of a radiographic film obtained simultaneously.…”

The effects of beam hardening on digital subtraction radiography

“…The relatively recent introduction of quantitative assay methods into the application of digital subtraction radiography in dentistry has spawned a variety of approaches (1)(2)(3)(4)(5)(6)(7)(8). Results from these studies and the work of previous investigations suggest that many different sources of error can contribute to inaccuracies in the estimation of osseous lesions.…”

“…Changes in contrast attributable to uncontrolled variations in x-ray exposure and film processing also have been shown to be major contributors to quantitative error (1). This source has been reduced successfully through the development of ingenious algorithms which monotonically map the dynamic range of one image or reference standard into that of another (6)(7)(8)10). Theory suggests that yet another source of error can influence quantitative measurements in dental radiology.…”

Digital image ratio: a new radiographic method for quantifying changes in alveolar bone. Part II: Clinical application

“…In a previous paper (1) we described a new technique, Digital Image Ratio (DIR), which theoretically avoids some of the drawbacks of other techniques (2)(3)(4)(5)(6)(7). This technique was validated using standards.…”