Evaluating mandibular cortical index quantitatively will not, and its cost if used indiscriminately.5 The density of the body of the mandible as measured most reasonable health care strategy for bone by dual energy X-ray dual absorptiometry. They densitometry provision seems to be its indication reported that MCI was significantly related to in a selective approach.4,6,7 bone mineral density of the body of the mandible The dentist is often the most regularly visited but there were limitations in its repeatability.14 doctor in the elderly population whom are also Taguchi et al evaluated MCI and mandibular under the risk of osteoporosis and associated cortical width on panoramic radiographs and fractures, and dental radiographs are the most compared them with bone mineral density of frequently used imaging modalities for these either the lumbar spine or the femoral neck. patients. The Food and Drug Administration They concluded that the odds ratio of having and American Dental Association recommend osteoporosis was 5.90 in women identified by screening radiography for every newly edentulous cortical width and 8.66 in women identified by patient because of high prevalence of findings cortical shape of the mandible.15 Again, in another such as root fragments and radiolucencies.8 study, Taguchi et al evaluated the effectiveness Panoramic radiography is commonly used of MCI in discriminating osteoporotic patients in large intuitional settings as a method of with 60 observers from 16 countries of the world screening partially and fully edentulous patients. and reported that the overall mean sensitivity, It is reported that in Japan 10 million panoramic specificity, positive predictive value, and negative radiographs are taken annually,9 and it is reported predictive value of the 60 observers in identifying that between 1998 and 1999, approximately women with osteoporosis by cortical erosion 2.05 million panoramic radiographs were taken panoramic radiographs were 82.5, 46.2, 46.7, and in the general dental service in England and 84% respectively.16 The repeatability of this index Wales.9 Researchers have developed a number is also evaluated and while some studies were of panoramic based mandibular indices, reporting satisfactory levels of agreement,11-13,17 image processing and analyzing techniques others were reporting lower levels of agreement, for quantification of mandibular bone mass especially between different observers even and trabecular architecture to discriminate among expert observers.14,18 As a consequence of osteoporotic patients from non-osteoporotic this finding, the authors reported that this limits ones. The thickness of the mandibular cortical the technique’s applicability clinically.18 bone is decreased in osteoporoic patients10 and Fractal analysis is a mathematical technique inferior border of the mandible is more porous which is helpful in the quantification of complex than controls.11-13 Mandibular cortical index (MCI) structures.19 The fractal dimension describes has been developed to assess osteoporosis in the how an object occupies space and is related to the cortical area of the mandible using panoramic complexity of its structure: it gives a numerical radiographs.12 In this technique, the inferior measure of the degree of boundary irregularity cortex on both sides of the mandible, distal to the or surface roughness.20,21 Lacunarity was initially mental foramen is classified into three groups introduced by Mandelbrot as a means of further according to the following criteria: classifying fractals and textures which had the 1. Cl 1: The endosteal margin of the cortex is same FD and a very different visual appearance.21 even and sharp on both sides of the mandible. Lacunarity is a measure of how the fractal fills 2. Cl 2: The endosteal margin has resorptive space, if the fractal is dense the lacunarity is cavities with cortical residues one to three layers small, the lacunarity increases with coarseness. thick on one or both sides. Higher lacunarity values indicate wider range 3. Cl 3: The endosteal margin consists of thick of sizes of structures within an image.22 An cortical residues and is clearly porous. advantage of lacunarity is that it is not predicated Mandibular cortical index is found to be useful in on fractalness or self similarity, and is therefore evaluating the patients for the risk of osteoporosis useful for natural images and also medical in various studies. In a study, Horner and Devlin images that may show at most only a limited evaluated whether a relationship exists between fractalness.22 These techniques are quantitative mandibular cortical index and bone mineral techniques and have no observer dependency. 284 European Journal of Dentistry