Use of fractal analysis in dental images: a systematic review.

OBJECTIVES: This study reviewed the use of fractal analysis (FA) in dental images. METHODS: A search was performed using PubMed, MEDLINE, LILACS, Web of Science and SCOPUS databases. The inclusion criteria were human studies in the English language, with no date restriction. RESULTS: 78 articles were found in which FA was applied to panoramic radiographs (34), periapical radiographs (21), bitewing radiographs (4), cephalometric radiograph (1), cone beam CT (15), micro-CT (3), sialography (2), and ultrasound (2). Low bone mineral density (21) and systemic or local diseases (22) around the bone of dental implants were the main subjects of the study of FA. Various sizes and sites of the regions of interest were used to evaluate the bone structure. Different ways were used to treat the image and to calculate FA. FA of 43 articles showed significant differences in the comparison of groups, mainly between healthy and sick patients. CONCLUSIONS: FA in Dentistry has been widely applied to the study of images. Panoramic and periapical radiographs were those most frequently used. The Image J software and the box-counting method were extensively adopted in the studies reviewed herein. Further studies are encouraged to improve clarification of the parameters that directly influence FA.

Mandibular radiomorphometric parameters of women with cemento-osseous dysplasia.

OBJECTIVE: To compare the radiomorphometric parameters of mandibular trabecular and cortical bone of females with and without cemento-osseous dysplasia (COD). METHODS: A retrospective cross-sectional paired study was conducted. Digital panoramic radiographs were obtained from females diagnosed in a public service of Oral Medicine. The participants were divided into two groups of 50 subjects each: females with a diagnosis of COD (COD group) and females without a diagnosis of COD (non-COD group), randomly chosen from the image database and paired for age. The radiomorphometric parameters analyzed were: mandibular cortical width (MCW), fractal dimension (FD) and mandibular cortical index (MCI). The paired t-test and Wilcoxon test were used to compare MCW and FD values and the McNemar-Bowker test compared the MCI. RESULTS: The mean age of both groups was 46.84 ± 11.38 years. The median MCW index was 3.12 mm (2.15-4.55) for the COD group and 3.52 mm (1.90-4.70) for the non-COD group (p = 0.034). The mean FD value of the COD group (1.2039 ± 0.0926) was lower than that of the non-COD group (1.2472 ± 0.0894) in the anatomical region of the interest of mandibular cortical bone (p = 0.031), while no difference was detected in alveolar trabecular bone. The C3 degree of MCI was more frequent in the COD group (p = 0.009). CONCLUSION: Females with COD had lower values of radiomorphometric parameters in mandibular cortical bone than females of the same age without COD. These results suggest that, in addition to the dental care recommended in the literature, COD females also require more attention and screening for low bone mineral density.

Digital panoramic radiography and cone-beam CT as ancillary tools to detect low bone mineral density in post-menopausal women.

OBJECTIVES: To evaluate the usefulness of the mandibular cortical index (MCI) obtained by digital panoramic radiography (DPR) and by panoramic reconstruction (PR) of cone-beam CT (CBCT) with three different slice thicknesses for the screening of low bone mineral density (BMD) in post-menopausal women. METHODS: Two trained oral and maxillofacial radiologists assessed the MCI based on the morphology of the mandibular bone cortex (classified as C1, C2 or C3). The DPR and PR of CBCT with slice thicknesses of 5, 15 or 25 mm were compared to the BMD obtained by dual-energy X-ray absorptiometry (DXA) in post-menopausal women. Measures related to accuracy were calculated with MedCalc software. The confidence interval was set at 95%. RESULTS: 54 women (mean age 58.70 ± 7.35 years) participated in the study. The sensitivity and specificity values obtained for DPR were 52.6% and 56.2%, respectively, and values for PR of CBCT with 5, 15, and 25 mm slice thicknesses were 63.1% and 43.7%, 50.0% and 50.0%, and 52.6% and 62.5%, respectively. For the tools evaluated, the positive likelihood ratio ranged from 1.00 to 1.40 and negative likelihood ratio from 0.76 to 1.00. The positive predictive value (PPV) ranged from 70.4 to 76.9% and the negative predictive value (NPV) from 29.6 to 35.7%. Among the examinations, the highest value for area under the curve (AUC) was obtained for CBCT with 25 mm slice thickness (57.6%). CONCLUSIONS: The MCI calculated by DPR and CBCT differed with regard to accuracy. Within the limitations of this study, the PR of CBCT with 25 mm slice thicknesses seems to be the most accurate among the examinations evaluated. Should the dentist be attentive, DPR and CBCT may be useful tools for the screening of low BMD in post-menopausal women, facilitating their timely referral for further assessment.