Effects of hyperlipidemia on trabecular and cortical structures of the mandible

Abstract

Objectives: To evaluate the mandibular bone structure of patients with hyperlipidemia by fractal dimension (FD) analysis and panoramic radiomorphometric indices including mandibular cortical thickness measurement, panoramic mandibular index (PMI), mandibular cortical index (MCI) and to compare with the healthy group.

Methods: In total, 60 panoramic radiographs were included, including panoramic radiographs of 30 individuals with hyperlipidemia and 30 individuals with systemically healthy. FD analysis in the mandibular condyle, angle of the mandible, the distal side of the second premolar and anterior to mental foramen, PMI, MCI, and mandibular cortical thickness measurements were evaluated on radiographs. Independent samples t-test was used for differences between healthy and hyperlipidemia groups with regard to age and PMI. Repeated measurement of variance with one within and one between factors in the comparison of four regions and two groups in terms of FD and cortical thickness measurements. Following this analysis, significant differences were detected by post-hoc Sidak test. Fisher-Freeman-Halton analysis was applied to determine the relationship between categorical variables.

Results: FD values of the hyperlipidemic patients were found to be lower than the healthy group. Between the hyperlipidemic and healthy groups, there was a difference in the angle of the mandible FD values (p = 0.020). There were no differences in the cortical thickness measurements and PMI between the groups (p > 0.05). There was a difference in MCI values between the groups (p < 0.05).

Conclusion: The trabecular structure of the angle of the mandible and the cortical bone structure of the mandible were found to be negatively affected by hyperlipidemia.

Keywords: Fractals; Hyperlipidemias; Osteoporosis; Radiography.

Figure 1.

a. Selected regions for fractal analysis in panoramic radiography: FD1: the subcortical area in the condyle, FD2: the supracortical area above the angle of the mandible, FD3: above the mandibular canal distal side to the second premolar, FD4: anterior to the mental foramen b. Cropped region of interest c. From left to right for the upper row; Addition Gaussian blur filter, Subtracted blurred image from the cropped image, Addition of a gray value of 128 to each pixel, Binarization. From left to right for the top row; Erosion, Dilatation, Inversion, Skeletonizion.

Figure 2.

Measurements of mandibular cortical thickness in the right mandible; dashed line: for the posterior index, 2.5 cm posterior to the mental foramen, parallel to the long axis of the mandible and straight line: 1 cm anterior and posterior to the mental foramen and drawn for the anterior and molar index, which is drawn parallel to the long axis of the mandible. Symphysis index (SI), anterior index (AI), molar index (MI), posterior index (PI). Measurement of panoramic mandibular index in the left mandible (PMI = A/B).

Figure 3.

MCI (Klemetti index) assessment on cropped panoramic images a. C1: Klemetti index 1; normal cortex: the endosteal margin of the cortex is matched and tapered on both sides, b. C2: Klemetti index 2; moderately worn cortex: endosteal margin, lacunar resorption resulting in semilunar defects or formation of endosteal cortical residues. MCI, mandibular cortical index.

Figure 4.

Bland–Altman plots of the compatibility of first and second fractal dimension measurements made from the condyle (FD1), angle of mandible (FD2), distal side-to the second premolar (FD3) and anterior to the mental foramen (FD4) regions.

Figure 5.

Bland–Altman plots of compliance with first and second cortical thickness (symphysis index, anterior index, molar index, posterior index) and panoramic mandibular index measurements.