Assessment of the Mandibular Osseous Architecture in Cleft Lip and Palate Using Fractal Dimension Analysis: A Pilot Study

Abstract

Background/Objectives: Although there has been extensive research on the orofacial morphologic effects of cleft lip and palate (CLP), the effects of CLP on mandibular structures remain largely unknown. The aim of this study was to investigate the trabeculation differences in the mandibular osseous architecture of patients with bilateral CLP (BCLP) and left-sided unilateral CLP (UCLP) using fractal dimension (FD) analysis and to compare these findings with healthy controls without CLP. Methods: A total of 63 patients (27 females, 36 males) with a mean age of 9.69 ± 1.5 years in the pre-peak growth stage were divided into three groups (n = 21 per group): the control group (CG), the BCLP group, and the UCLP group. The FD analysis was conducted on selected regions of interest (ROIs) from the mandibular condyle, angulus, corpus, and coronoid areas in TIFF-formatted panoramic radiographs. Statistical analyses were performed using the paired t-test and ANOVA for parametric data, and the Wilcoxon and Kruskal-Wallis tests for nonparametric data. Statistical significance was set at p < 0.05. Results: The FD values obtained from the ROIs of the right condyle were found to be significantly lower in the BCLP group compared to the CG and UCLP groups (p < 0.05). Conversely, the FD values for the left condyle were significantly higher in the CG group (p < 0.05), while no significant differences were observed between the BCLP and UCLP groups (p > 0.05). The FD value of the left condyle in the UCLP group was found to be significantly lower than that of the right condyle (p < 0.05). In the CG group, the FD values for both the right and left mandibular condyle and corpus were significantly higher than those for the angulus and coronoid regions; in the UCLP group, only the FD values of the right mandibular condyle and corpus were significantly higher than those for the same regions (p < 0.05). Conclusions: The reduced FD values in the mandibular condyle of CLP patients during the pre-peak growth stage suggest a loss of trabeculation and lower metabolic activity, while similarly, reduced FD values in the corpus region contribute to delayed tooth eruption timing, likely due to decreased masticatory forces during the intercuspal position and altered occlusal relationships. Clinical Relevance: In treating CLP patients, particularly with orthopedic face masks, the reduction in metabolic activities in these areas should be considered to achieve the optimal mandibular growth and development, and dental eruptions during the distribution of force from the chin to the corpus and condyle.

Keywords: bilateral cleft lip and palate; fractal dimension analysis; metabolic activity; trabeculation; unilateral cleft lip and palate.

Figure 1

Schematic representation of the cephalometric parameters measured: S: sella, N: nasion, Po: porion, Or: orbitale, A: A point, B: B point, N ⟂: nasion perpendicular, FOP: functional occlusal plane. Red color: Cephalometric landmark points and abbreviations, Purple color: SNA angle, Light blue color: SNB angle, Green color: A to N ⟂ distance, Yellow color: Wits distance.

Figure 2

Yellow line: A sample calibrated based on the 11.65 mm mesiodistal distance of the mandibular left permanent first molar.

Figure 3

Yellow-colored ROIs for the right mandibular region: (1) condyle, (2) coronoid, (3) angulus, and (4) corpus. Green-colored ROIs for the left mandibular region: (5) condyle, (6) coronoid, (7) angulus, and (8) corpus.

Figure 4

(A) Duplicated ROI area image, (B) image blurring using the Gaussian filter, (C) subtraction of the blurred image from the original image, (D) addition of 128 gray tones, (E) conversion of the image to black and white using the thresholding method (Make Binary), (F) the removal of minor noise from the image via the erode function, (G) the enhancement and expansion of the most prominent regions of the image through the use of the dilate function, (H) the inversion of colors, and (I) the application of the skeletonize method to yield a skeletal appearance.

Figure 5

FD values of the right and left mandibular ROIs in the groups.

Figure 6

Right and left FD values of groups in the mandibular ROIs.