Influence of soft tissues on mandibular gray scale levels

Abstract

The purpose of this study was to analyze the gray levels, expressed in pixels, of the mandibular retromolar region, with regard to the influence of muscular and fat soft tissues near this region. Fifteen dry mandibles were X-rayed with the presence of soft tissue simulators. The radiographs were digitized and evaluated by Digora® software. A one cm thick layer of wax was used as a simulator of the muscular soft tissue. Animal fat samples of different thicknesses - 0.5, 1.0, 1.5 and 2.0 cm - were used as a simulator of the fat soft tissue. Results showed that the fat soft tissue simulator influenced the gray level values in pixels of the mandibular retromolar region when analyzed in different thicknesses using the Digora® digitized image software.

Comparison of changes in dental and bone radiographic densities in the presence of different soft-tissue simulators using pixel intensity and digital subtraction analyses

“…These results are in accordance with a previous study. 17 Furthermore, Wx, Wd and Bt showed an increased grey-level gain according to the increase in thickness.…”

“…3 As radiographic tissue density is derived from this attenuation coefficient degree, quantification of the density becomes more accurate when the influence of soft-tissue simulator materials is taken into consideration. 17 According to Souza et al, 17 different materials with the same thickness showed different optical densities in the mandibular bone area, using digitized film-based radiographic images. However, the differences with the methodology used in our study make it difficult to compare the findings.…”

“…3 The use of soft-tissue simulation materials having densities similar to the tissues found in patients in a real environment helps avoid exposure of patients to excessive radiation during in vivo studies. 4 Based on literature, the use of soft-tissue simulators, such as acrylic plates, 2,4-8 wax, 2,4,9,10 water, 11-14 wood 4,15,16 and bovine tissue 17 has been tested in different ways with respect to the nature and/or the thickness of the material put around dry mandibles. 2,5,16 It is important that these simulation materials are accurately reproducible, measurable and are ready for use in any circumstances.…”

“…18 The influence of soft-tissue simulators on mandible bone radiographic density has been shown previously using digitial intraoral radiography. 17 In a recent article, Schropp et al 2 evaluated the thickness of wax and acrylic used as soft-tissue simulation materials to obtain a radiographic density similar to that of the human cheek. This study showed that acrylic and wax with thicknesses of 14.5 mm and 13-17 mm, respectively, could simulate the human cheek in in vitro radiographic studies.…”

Validity of wax and acrylic as soft-tissue simulation materials used inin vitroradiographic studies

“…In most of such studies it has been considered important to simulate the soft tissues (cheek) by using a material interposed between the X-ray beam and the teeth/bone, because soft tissues change the absorption and increase scatter radiation, and may influence the contrast and density of the film (and thereby diagnostic accuracy). In fact, Souza et al 1 showed that animal fat samples of different thicknesses used as a soft-tissue simulator adjacent to the mandibular retromolar region influenced the resulting grey level values in digitized intraoral radiographs.…”