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Article

Fractal Dimension of the Condylar Bone Structure in Patients with Unilateral Condylar Hyperplasia: Cross-Sectional Retrospective Study

by
Adriana Assunta De Stefano
,
Ludovica Musone
,
Martina Horodynski
*,
Roberto Antonio Vernucci
and
Gabriella Galluccio
Department of Oral and Maxillofacial Sciences, Sapienza University of Rome, 00161 Rome, Italy
*
Author to whom correspondence should be addressed.
Appl. Sci. 2025, 15(7), 4063; https://doi.org/10.3390/app15074063
Submission received: 18 December 2024 / Revised: 20 March 2025 / Accepted: 29 March 2025 / Published: 7 April 2025
(This article belongs to the Special Issue Advances in Orthodontic Diagnosis and Treatment: Methods and Applications)
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Abstract

:

Featured Application

Fractal dimension (FD) may be useful in the diagnosis of mandibular condylar hyperplasia in patients with mandibular asymmetry as a rapid, simple and inexpensive technique for the identification of the condyle with active condylar hyperplasia.

Abstract

Unilateral condylar hyperplasia (UCH) is one of the causes of facial asymmetry, and it is characterized by increased growth in one of the mandibular condyles. In UCH, it is important to determine whether the metabolic activity of the hyperplastic condyle is still active. Fractal dimension (FD) analysis could be a non-invasive method to identify active metabolic activity. The aim of this study is to compare the FD of the hyperplastic condyle with the contralateral one in patients with facial asymmetry and positive bone scintigraphy and to compare the FD of the right and left condyles in symmetrical patients. A cross-sectional retrospective study of fifteen patients with facial asymmetry and positive bone scintigraphy and fifteen symmetrical patients was conducted. Clinical data and scintigraphy results were collected from medical records, and CBCT scans were used for the application of FD by pre-processing the images according to White and Rudolph and using ImageJ® (1.54p) software and the box-counting method. Wilcoxon’s t test was used to analyze the differences in FD between the hyperplastic and contralateral condyles in patients with UCH and between the right and left condyles in symmetrical patients. A p-value of <0.05 was considered statistically significant. The FD of the hyperplastic condyles was significantly higher than the contralateral one in the axial and coronal plane (p = 0.001). The analysis of FD of the mandibular condyle can be a useful non-invasive method to identify active UCH in patients with facial asymmetry.

1. Introduction

Facial asymmetry is defined as the presence of a clinically significant variation in the size, shape and position of bilateral structures on opposite sides of the mid-sagittal plane (MSP) of the craniofacial complex [1]. Facial asymmetry, in particular mandibular asymmetry, has been related to morphological and functional changes in the temporomandibular joint (TMJ) [2], especially dimensional [1], volume [3] and condylar position asymmetry [3,4] but also with the position and morphology of the mandibular fossa [5], unilateral disc displacement [6,7] and joint hypermobility [8,9].
In the same way, condylar growth alterations, such as condylar hyperplasia, which is characterized by an increased metabolic activity of one of the two condyles, can lead to asymmetrical mandibular development and therefore to facial asymmetry [10,11,12]. Unilateral condylar hyperplasia most frequently occurs in patients aged between 11 and 30 years, mainly affecting females [13], without a predominance for the left or the right side. Despite being described many years ago, the etiopathogenesis still remains unclear; in the literature, various theories have been suggested, which include, trauma, hormonal imbalance, infection, arthrosis, vascular disorders and a genetic role [14].
Common features include enlargement of the mandibular condyle and condylar neck and excessive growth of the mandibular body [15]. Additionally, condylar hyperplasia has been described as self-limiting, meaning that its progression can occur at any time [16]. Moreover, it can be active, which means it is characterized by un ongoing growth, or unactive, in which growth has stopped [17].
One of the most challenging features of unilateral condylar hyperplasia is identifying whether the abnormal growth of the condyle is still active [18]. In fact, therapeutic options for patients with active condylar hyperplasia are different from the ones that can be applied to patients with asymmetrical mandible but without active condylar growth [19]. The diagnosis is based on a combination of anamnesis, clinical exam, 2D and 3D radiographic images and bone scintigraphy. Bone scintigraphy represents an effective tool to identify if condylar growth is active or not with a pooled sensitivity of 0.71 (95% CI: 0.57–0.82) [18].
In the last years, single-photon emission computed tomography (SPECT) has been performed since it was defined to be more accurate and reliable compared to bone planar scintigraphy to evaluate condylar growth with a pooled sensitivity value of 0.90 (95% CI: 0.79–0.97) and a pooled specificity value of 0.95 (95% CI: 0.82–0.99) [18].
SPECT uses a radionuclide, technetium-99m (99mTc), to quantify its absorption within the bones [18]. In suspected condylar hyperplasia, the absorption of the radionuclide in the hyperplastic condyle is compared with the contralateral one; differences of more than 10% in absorption are interpreted as active condylar growth [20].
Although SPECT can identify condylar growth, its specificity can be questioned [21]. Indeed, it is difficult to determine what changed bone metabolism. For example, bone healing, inflammatory responses, tumors and metabolic diseases such as hyperparathyroidism can all lead to an augmented bone turnover [22,23]. The range of SPECT’s sensitivity and specificity described in the literature is very wide [18,21], so it is necessary to perform other additional exams for the diagnosis of condylar hyperplasia.
Different characteristics of the hyperplastic condyles of asymmetric patients with abnormal SPECT were identified by means of micro-CT scans, particularly a higher cortical porosity, a higher bone volume fraction, a considerably higher trabecular thickness and separation, a higher number of trabeculae and a lower degree of mineralization compared to the architecture of mandibular condyles not affected by active condylar hyperplasia [20]. Micro-CT is considered the gold standard for the assessment of bone morphology, although the high quality of micro-CT, high cost, radiation dose and the need for a bone sample preclude its use as a diagnostic test to assess the relationship between systemic bone turnover and condylar bone microstructure in patients with facial asymmetry [24].
Microstructural evaluation of condyle trabecular bone could also be assessed with the analysis of fractal dimension (FD) [25]. FD analysis is a statistical analysis of tissues used to describe complex figures and structural models that defines the complexity of a structure by measuring with fractal mathematics the similarities present inside the structure [26,27].
Fractal analysis can be performed with different techniques, such as encompassing multifractal analysis, mass methods, box-counting and lacunarity analysis, and each technique offers a perspective on the fractal characteristics of biological structures [26]. All these techniques applied to radiographic images can quantify complex geometric figures (fractals), therefore enabling a qualitative bone evaluation with a non-invasive method [28]. FD analysis performed with the box-counting method has successively been used to investigate the quantity of trabeculae present inside bone marrow, thereby assessing the integrity and quality of bone [29]. In the literature, studies about the FD accuracy agree that FD is a valid technique when compared to the bone mineral density screening test using periapical and panoramic X-rays [30,31]; therefore, it has been applied to evaluate modifications of the periapical bone region after endodontic therapy [27].
The FD value increases with an increase in a structure’s complexity; therefore, a higher FD value indicates that the structure is more complex. Bone measurable characteristics are the trabecular distribution, bone thickness and bone density [26,27]. The structure and distribution of bone trabeculae is determined by the porosity, bone thickness and anisotropy. Trabecular bone structure analysis to evaluate bone health has found important applications in medical areas [26]. FD can distinguish different densities in bone areas with a linear correlation between bone density and FD on histological samples [25].
FD in orthodontics was applied to evaluate bone structure. Servais et al. [32] analyzed CBCT scans of patients with maxillary impacted canines and found an increase in maxillary bone around the unilateral impacted canines compared to the non-impacted side; however, the FD differences were not statistically significant. Rothe et al. [33] also used FD to study the trabecular structure of the mandible as an indicator of possible orthodontic relapse in patients undergoing orthodontic treatment, and a statistically nonsignificant difference in the FD of the bone structure emerged between the relapse and stability groups. Furthermore, Darawsheh et al. [34] found a statistically significant difference in FD when the authors analyzed 51 CBCT scans to investigate the correlation between FD and the maturation stages of the midpalatal suture; their results revealed a 100% sensitivity, 93.7% specificity, 9.5% false positive rate and 0% false negative rate of FD analysis for predicting midpalatal suture maturation, concluding that it represents a valid tool to stage the maturation of the midpalatal suture.
FD to evaluate condylar bone structure was applied to panoramic X-rays and to Cone Beam Computed Tomography (CBCT) scans, and different dimensions and different methods have been used to analyze the images; however, the most used methods to calculate FD are represented by the Image J® software and the box-counting method [26].
The evaluation of FD in asymmetrical patients with condylar hyperplasia has not yet been studied, and it might be useful to assess whether the FD value of the hyperplastic condyle differs from that of the contralateral one in patients with active condylar hyperplasia, to define a non-invasive screening method. For this reason, the aim of this study is to compare the FD of the hyperplastic condyle with that of the contralateral condyle in patients with facial asymmetry and positive bone scintigraphy.

2. Materials and Methods

2.1. Study Population

This retrospective study followed the ethical guidelines established in the Declaration of Helsinki on medical protocol and recommendations for human research. All participants obtained informed consent for the use of their data and records, and their confidentiality was maintained throughout the study. The Institutional Ethics Committee of Policlinico Umberto I approved this study (Prot. No. 4632).
To constitute the study group for this retrospective study, the initial diagnostic records were examined of patients who had been referred within the previous ten years to the Orthodontics Operational Unit of the Department of Odontostomatological and Maxillofacial Sciences at the University “La Sapienza” of Rome.
Patients of both sexes older than 10 years who provided complete personal and anamnestic data, informed consent for the use of their data and records for research purposes and CBCT of the maxillofacial complex were evaluated.
Patients with facial asymmetry (horizontal distance from the menton to the midfacial line > 4 mm) and a SPECT result difference of more than 10% between the mandibular condyles were selected for the Asymmetrical patients group. The Symmetrical patients group consisted of patients without mandibular deviation (horizontal distance from the menton to the midfacial line < 2 mm).
Patients with facial neoplasia, syndromic disorders, congenital craniofacial anomalies, trauma or previous facial fractures were not included in either group. In addition, individuals who had previously undergone maxillofacial surgery, orthodontic or gnathological treatment or who were taking long-term medication were not included.

2.2. Fractal Dimension Analysis

CBCT scans of all selected patients were used to analyze the mandibular condylar bone structure utilizing fractal dimension, according to White and Rudolph [29] and using Image J® (National Institutes of Health, Bethesda, MD, USA) software by the box-counting method. A single observer assessed each CBCT image.
Three CBCT scans were selected for each condyle. For the selection of the CBCT scan, first, the axial slice of the condyle was examined; the axial slice with the largest medio-lateral dimension of the condyloid was selected for the acquisition of the ROI in this plane. For the ROI in the coronal plane, coronal sections were taken parallel to the long axis of the condyloid in the selected axial image, and the coronal section corresponding to the largest mediolateral dimension of the condyloid in the axial view was selected. In the sagittal plane, the sagittal sections perpendicular to the long axis of the condyle in the axial image were evaluated, and the sagittal section corresponding to the central portion of the condyle in the mediolateral direction was selected.
The region of interest (ROI) was selected in the superior medial portion of the condyle in the coronal plane, in the medial portion of the condyle in the axial plane and in the superior medial portion of the condyle in the sagittal plane. The ROI was selected in the subcortical area of the condyle to ensure that the ROI was inside the limit of cortical bone. Standardized ROIs were of different dimensions: 30 × 30 pixels in the coronal plane, 35 × 15 pixels in the axial plane and 20 × 20 pixels in the sagittal plane. The scan resolution was 2.2857-pixel × mm with voxel dimensions of 0.4824 × 0.4824 × 3.2748 mm3 (Figure 1a–c).
After the selection, the ROIs were converted into JPEG format (400 DPI resolutions) and transferred to the Image J® (National Institutes of Health, MD, USA) software for processing. The ROIs were cut and duplicated (Figure 2a). To remove brightness due to soft tissue presence and bone thickness variations, ROIs were blurred using the “Gaussian blur” filter (Figure 2b). The blurred image was subtracted from the first one (Figure 2c), and a 128 grayscale value was added to each pixel on the resultant image to ensure adequate discrimination between the trabecular structure and the bone marrow (Figure 2d). The resultant image was binarized (Figure 2e), eroded (Figure 2f), dilated (Figure 2g), inverted (Figure 2h) and skeletonized (Figure 2i) in sequence. The skeletonized image was divided into boxes of 2-, 3-, 4-, 6-, 8-, 12-, 16-, 32- and 64-pixel sizes using the “fractal box count” on the “analyze” menu. A single numerical value of FD was obtained.

2.3. Statistical Analysis

Descriptive analysis was performed using SPSS 27.0 (IBM Corp., Armonk, NY, USA, 2011). The means and standard deviations of FD were calculated for the hyperplastic and contralateral condyles. The Kolmogorov–Smirnov test was used to verify the normal distribution of continuous variables. To analyze the differences in FD between hyperplastic and contralateral condyles in asymmetrical patients and between the right and left condyles in symmetrical patients, the Wilcoxon signed-rank test was conducted. A p value < 0.05 was considered statistically significant.

3. Results

After applying the inclusion and exclusion criteria, the sample of this study resulted in thirty patients (12 males and 18 females, mean age of 22.67 years ± 10.15). The Asymmetrical patients group with unilateral condylar hyperplasia and with positive SPECT resulted in fifteen patients (7 males and 8 females, mean age of 23.40 ± 10.46). The Symmetrical patients group resulted in fifteen patients (5 males and 10 females, mean age of 21.93 ± 10.14).
In the Asymmetrical patients group, the FD was higher in all three planes in the hyperplastic condyle compared to the contralateral condyle; a statistically significant difference was found in FD between the condyles in the axial and coronal planes (p < 0.05), while in the sagittal projection, the difference was not statically significant (p = 0.110). In the Symmetrical patients group, the differences in FD between the right and left condyles were not statistically significant in any plane (Table 1).

4. Discussion

This cross-sectional retrospective study was conducted to investigate if there were any differences in the FD of the condylar bone structure between affected condyles of patients with unilateral condylar hyperplasia with positive SPECT and the contralateral unaffected ones and between the condyles of symmetrical patients.
FD analysis is increasing in popularity because it facilitates the identification of possible abnormalities and the assessment of the severity of diseases affecting bone structure [35]. FD analysis is often applied in dentistry to investigate the complex structure of bone, in order to evaluate bone microstructure [25,32]. FD was used in orthodontics to study the bone density around impacted canines [32], to evaluate orthodontic-induced osteoclastic activity [33], to evaluate mid-palatal sutures [36] and to identify risk factors implied in orthodontic relapse [33]. Condylar FD was analyzed in patients with temporomandibular disorders [37,38,39] and systemic conditions [40,41]; to study the effects of functional orthodontics [42,43], multibrackets and aligner therapy [44]; and to evaluate different skeletal patterns [45].
Diverse studies have used FD analysis to assess the trabecular structure of the mandibular condyle in panoramic radiographs, and the results have been found to be valid and reliable [35,46,47]. Although there are numerous studies in which FD analysis has been conducted, there are some difficulties in the standardization of this technique; in fact, the type and resolution of the processed image [48] and the size, site and shape of the ROI [49] could influence the standardization of FD. Moreover, it was found that in FD performed on CBCT, voxel size can modify the FD results [50]. Another paper reported a variation in FD according to the resolution and exposure time, in particular, with higher resolutions and shorter exposure times leading to higher FD values [48]. Fortunately, in the literature, it is reported that fractal analysis is not influenced by radiographic settings such as milliampere, kilovolt peak or X-ray beam angle [51] and lossy image compression. High-resolution settings together with low-compression levels resulted in the most optimized FD values [52]. The public domain software ImageJ has been used in several imaging studies in medicine and dentistry [26]; the description of its use in the literature has allowed a standardized process that allows for comparison of the results obtained.
A more accurate assessment of the anatomy and morphology of the mandibular condyle trabeculae is made possible by CBCT imaging, which provides higher resolution and more information of the trabecular pattern of the bones [12].
CBCT scans of hyperplastic condyles were not used to compare FD with contralateral unaffected condyles in any of the published studies known to the authors. Alpaydin et al. [35] analyzed FD on panoramic X-rays of asymmetric patients and found statistically significant differences in the FD values: FD was higher in the left condyle in patients with right asymmetry and in the right condyle in patients with left asymmetry. They concluded that FD was greater in the condyle responsible for the asymmetry. These results are in line with those obtained in the present study in that all the hyperplastic condyles had higher FD values than the unaffected condyles. Furthermore, the differences in FD were statistically significant in the axial plane of the hyperplastic condyles.
The mandibular condyles with hyperplasia shown by micro-CT analysis had different bone structures than the unaffected condyles, showing a higher cortical porosity, higher bone volume fraction, higher trabecular thickness and trabecular separation, higher number of trabeculae and lower mineralization [20]. Focal anomalies of the bone microarchitecture, including foci of osteosclerosis, were detected by three-dimensional micro-CT models. These foci contained islands of calcified cartilage matrix with live chondrocytes, according to histological sections [53]. Hyperplastic condyles show a thicker cartilage stratum than healthy condyles [54,55]. This stratum might be more evident in the axial and coronal planes, which might explain why a significant difference in FD was shown between the hyperplastic and contralateral condyle in these projections.
There are several limitations of this study. No age groups were considered in the sample, and no sex differentiation was made, which could affect the FD results, so the results do not allow conclusions to be drawn without the risk of bias. In addition, condylar hyperplasia was not classified, and the sagittal or vertical intermaxillary relationship was not considered.
Despite the limitations of this study, the results obtained show that FD analysis could be used to differentiate hyperplastic condyles in patients with facial asymmetry. FD could be useful in screening condylar hyperplasia as a quick, simple and inexpensive examination.
To extend this line of research and confirm the results of this study, future research on FD in diverse types of facial asymmetry and correlations with the metabolic activity of bone tissue by SPECT are needed. Prospective studies could lead to alternative investigations for analyzing the bone structure histopathology of the hyperplastic condyle after surgery and correlating its figures to the FD values calculated on the pre-surgery CBCT scans, as well as comparing the FD of hyperplastic condyles with the results of a micro-CT scan. Moreover, it would be interesting to extend FD analysis to non-pathologic condyles in patients with different skeletal patterns to study if there are baseline values of FD that could be considered as physiological. Similarly, it would be interesting to establish the FD for patients of different age and ethnic groups. This kind of investigation could provide an easy tool for clinicians to identify bone structure abnormalities of the condyles.

5. Conclusions

The results of this study indicate that the FD values of the hyperplastic condyle in patients with positive SPECT are higher than the ones calculated for the unaffected condyle, while the differences in FD values between the right and left condyles in symmetrical patients are not statistically significant, which is why the analysis of the fractal dimension of the mandibular condyle could be a useful non-invasive tool to identify active condylar hyperplasia in patients with facial asymmetry.

Author Contributions

Conceptualization, A.A.D.S. and G.G.; methodology, L.M.; software, L.M.; validation, A.A.D.S. and M.H.; formal analysis, R.A.V.; investigation, M.H. and R.A.V.; data curation, A.A.D.S. and L.M.; writing—original draft preparation, L.M.; writing—review and editing, A.A.D.S. and M.H.; visualization and supervision, G.G. and A.A.D.S.; project administration, G.G.; funding acquisition, A.A.D.S. All authors have read and agreed to the published version of the manuscript.

Funding

The authors did not receive support from any organization for the submitted work.

Institutional Review Board Statement

The study was conducted in accordance with the Declaration of Helsinki and approved by the Institutional Ethics Committee of Policlinico Umberto I (Prot. n.4632).

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

The data presented in this study are available on request from the corresponding author. The data are not publicly available due to privacy and ethical restrictions.

Conflicts of Interest

The authors declare no conflicts of interest. The funders had no role in the design of the study; in the collection, analyses, or interpretation of data; in the writing of the manuscript; or in the decision to publish the results.

References

  1. Cheong, Y.W.; Lo, L.J.L. Facial asymmetry: Etiology, evaluation, and management. Chang Gung Med. J. 2011, 34, 341–351. [Google Scholar] [PubMed]
  2. Marques, F.B.C.; de Lima, L.S.; Oliveira, P.L.E.; Magno, M.B.; Ferreira, D.M.T.P.; de Castro, A.C.R.; Maciel, J.V.B.; de Oliveira Ruellas, A.C.; Maia, L.C. Are temporomandibular disorders associated with facial asymmetry? A systematic review and meta-analysis. Orthod. Craniofacial Res. 2020, 24, 1–16. [Google Scholar]
  3. Kim, J.Y.; Kim, B.J.; Park, K.H.; Huh, J.K. Comparison of volume and position of the temporomandibular joint structures in patients with mandibular asymmetry. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. 2016, 122, 772–780. [Google Scholar]
  4. Srivastava, D.; Singh, H.; Mishra, S.; Sharma, P.; Kapoor, P.; Chandra, L. Facial asymmetry revisited: Part I—Diagnosis and treatment planning. J. Oral Biol. Craniofacial Res. 2018, 8, 7–14. [Google Scholar] [CrossRef]
  5. da Silva, N.C.F.; de Aquino, É.R.B.; Mello, K.C.F.R.; Mattos, J.N.R.; Normando, D. Orthodontists’ and laypersons’ perception of mandibular asymmetries. Dent. Press J. Orthod. 2011, 16, 38.e1–38.e8. [Google Scholar]
  6. Vernucci, R.A.; Aghazada, H.; Gardini, K.; Fegatelli, D.A.; Barbato, E.; Galluccio, G.; Silvestri, A. Use of an anatomical mid-sagittal plane for 3-dimensional cephalometry: A preliminary study. Imaging Sci. Dent. 2019, 49, 159–169. [Google Scholar]
  7. Guercio-Monaco, E.; De Stefano, A.; Impellizzeri, A.; Galluccio, G. Association between the temporomandibular joint disc position on magnetic resonance imaging and the mandibular deviation on posteroanterior cephalogram: A cross-sectional study in adolescents. Clin. Ther. 2020, 171, e509–e516. [Google Scholar]
  8. Boboc, A.M.; De Stefano, A.; Impellizzeri, A.; Barbato, E.; Galluccio, G. Correlation between generalized joint hypermobility and temporomandibular joint disc displacement in adolescent patients: Magnetic ResonanceImaging study. Eur. J. Paediatr. Dent. 2022, 23, 106–110. [Google Scholar]
  9. De Stefano, A.A.; Boboc, A.M.; Horodynski, M.; Impellizzeri, A.; Serritella, E.; Galluccio, G. Severity of Temporomandibular Joint Disc Displacement and Generalized Joint Hypermobility in Growing Patients: A Cross-Sectional Magnetic Resonance Image Study. Appl. Sci. 2023, 13, 12495. [Google Scholar] [CrossRef]
  10. Vellone, V.; Costantini, A.M.; Ramieri, V.; Alunni Fegatelli, D.; Galluccio, G.; Cascone, P. Unilateral Condylar Hyperplasia: A Comparison with Two Open-Source Softwares. J. Craniofacial Surg. 2020, 31, 475–479. [Google Scholar]
  11. Vernucci, R.A.; Mazzoli, V.; Galluccio, G.; Silvestri, A.; Barbato, E. Unilateral hemimandibular hyperactivity: Clinical features of a population of 128 patients. J. Cranio-Maxillofac. Surg. 2018, 46, 1105–1110. [Google Scholar] [CrossRef] [PubMed]
  12. De-Stefano, A.A.; Di-Chicco, A.; Impellizzeri, A.; Serritella, E.; Guercio-Mónaco, E.; Galluccio, G. Unilateral Condylar Hyperplasia: A Thee-Dimensional CBCT Morphometric and Volumetric Evaluation of Mandibular Condyle by Open-Source Softwares. Int. J. Morphol. 2021, 39, 1164–1170. [Google Scholar] [CrossRef]
  13. Elbaz, J.; Wiss, A.; Raoul, G.; Leroy, X.; Hossein-Foucher, C.; Ferri, J. Condylar Hyperplasia: Correlation Between Clinical, Radiological, Scintigraphic, and Histologic Features. J. Craniofacial Surg. 2014, 25, 1085–1090. [Google Scholar] [CrossRef] [PubMed]
  14. Toh, A.Q.J.; Becking, A.G.; Leung, Y.Y. Mirror-image unilateral condylar hyperplasia in monozygotic twins. Int. J. Oral Maxillofac. Surg. 2021, 50, 1177–1181. [Google Scholar] [CrossRef]
  15. Perriman, A.; Uthman, A. Unilateral condylar hyperplasia. Br. J. Oral Surg. 1970, 8, 273–280. [Google Scholar] [CrossRef]
  16. López, D.F.; Ríos Borrás, V.; Muñoz, J.M.; Cardenas-Perilla, R.; Almeida, L.E. Spect/ct correlation in the diagnosis of unilateral condilar hyperplasia. Diagnostics 2021, 11, 477. [Google Scholar] [CrossRef]
  17. Anastasi, M.R.; Centofanti, A.; Favaloro, A.; Freni, J.; Nicita, F.; Vermiglio, G.; Anastasi, G.P.; Cascone, P. Unilateral “Inactive” Condylar Hyperplasia: New Histological Data. J. Funct. Morphol. Kinesiol. 2024, 9, 217. [Google Scholar] [CrossRef]
  18. Saridin, C.P.; Raijmakers, P.G.H.M.; Tuinzing, D.B.; Becking, A.G. Bone scintigraphy as a diagnostic method in unilateral hyperactivity of the mandibular condyles: A review and meta-analysis of the literature. Int. J. Oral Maxillofac. Surg. 2011, 40, 11–17. [Google Scholar] [CrossRef]
  19. Ghawsi, S.; Aagaard, E.; Thygesen, T.H. High condylectomy for the treatment of mandibular condylar hyperplasia: A systematic review of the literature. Int. J. Oral Maxillofac. Surg. 2016, 45, 60–71. [Google Scholar] [CrossRef]
  20. Karssemakers, L.H.E.; Nolte, J.W.; Tuinzing, D.B.; Langenbach, G.E.J.; Raijmakers, P.G.; Becking, A.G. Microcomputed tomographic analysis of human condyles in unilateral condylar hyperplasia: Increased cortical porosity and trabecular bone volume fraction with reduced mineralisation. Br. J. Oral Maxillofac. Surg. 2014, 52, 940–944. [Google Scholar] [CrossRef]
  21. Chan, B.H.; Leung, Y.Y. SPECT bone scintigraphy for the assessment of condylar growth activity in mandibular asymmetry: Is it accurate? Int. J. Oral Maxillofac. Surg. 2018, 47, 470–479. [Google Scholar]
  22. Kim, J.H.; Kim, Y.K.; Kim, S.G.; Yun, P.Y.; Kim, J.D.; Min, J.H. Effectiveness of bone scans in the diagnosis of osteoarthritis of the temporomandibular joint. Dentomaxillofac. Radiol. 2012, 41, 224–229. [Google Scholar] [CrossRef]
  23. Ahn, B.C.; Kim, H.J.; Lee, S.W.; Yoo, J.; Choi, J.K.; Lee, J. New quantitative method for bone tracer uptake of temporomandibular joint using Tc-99m MDP skull SPECT. Ann. Nucl. Med. 2009, 23, 651–656. [Google Scholar]
  24. Irie, M.S.; Rabelo, G.D.; Spin-Neto, R.; Dechichi, P.; Borges, J.S.; Soares, P.B.F. Use of Micro-Computed Tomography for Bone Evaluation in Dentistry. Braz. Dent. J. 2018, 29, 227–238. [Google Scholar]
  25. Perrotti, V.; Iezzi, G.; De Sanctis, A.; Pasculli, A.; Piattelli, A.; Aprile, G. Correlation between bone density and fractal dimension: A pilot study. Nonlinear Phenom. Complex Syst. 2020, 23, 130–132. [Google Scholar]
  26. Kato, C.N.A.O.; Barra, S.G.; Tavares, N.P.K.; Amaral, T.M.P.; Brasileiro, C.B.; Mesquita, R.A.; Abreu, L.G. Use of fractal analysis in dental images: A systematic review. Dentomaxillofac. Radiol. 2020, 49, 20180457. [Google Scholar]
  27. Chen, J.; Zheng, B.; Chang, Y.H.; Shaw, C.C.; Towers, J.D.; Gur, D. Fractal analysis of trabecular patterns in projection radiographs: An assessment. Investig. Radiol. 1994, 29, 624–629. [Google Scholar]
  28. Kasimoglu, Y.; Tuna, E.B.; Rahimi, B.; Marsan, G.; Gencay, K. Condylar asymmetry in different occlusion types. Cranio—J. Craniomandib. Pract. 2015, 33, 10–14. [Google Scholar] [CrossRef] [PubMed]
  29. White, S.C.; Rudolph, D.J. Alterations of the trabecular pattern of the jaws in patients with osteoporosis. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endodontology 1999, 88, 628–635. [Google Scholar]
  30. Ince Yusufoglu, S.; Ugur Aydin, Z.; Tulumbaci, F.; Bayrak, S. Evaluation of different Apexification treatments of teeth with immature apices and apical periodontitis on the fractal dimensions of trabecular bone. Aust. Endod. J. 2021, 47, 163–169. [Google Scholar] [PubMed]
  31. Kavitha, M.S.; An, S.Y.; An, C.H.; Huh, K.H.; Yi, W.J.; Heo, M.S.; Lee, S.S.; Choi, S.C. Texture analysis of mandibular cortical bone on digital dental panoramic radiographs for the diagnosis of osteoporosis in Korean women. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. 2015, 119, 346–356. [Google Scholar] [PubMed]
  32. Servais, J.A.; Gaalaas, L.; Lunos, S.; Beiraghi, S.; Larson, B.E.; Leon-Salazar, V. Alternative cone-beam computed tomography method for the analysis of bone density around impacted maxillary canines. Am. J. Orthod. Dentofac. Orthop. 2018, 154, 442–449. [Google Scholar] [CrossRef]
  33. Rothe, L.E.; Bollen, A.M.; Little, R.M.; Herring, S.W.; Chaison, J.B.; Chen, C.S.K.; Hollender, L.G. Trabecular and cortical bone as risk factors for orthodontic relapse. Am. J. Orthod. Dentofac. Orthop. 2006, 130, 476–484. [Google Scholar] [CrossRef]
  34. Darawsheh, A.F.; Kolarovszki, B.; Hong, D.H.; Farkas, N.; Taheri, S.; Frank, D. Applicability of Fractal Analysis for Quantitative Evaluation of Midpalatal Suture Maturation. J. Clin. Med. 2023, 12, 4189. [Google Scholar] [CrossRef]
  35. Alpaydin, M.T.; Buyuk, S.K.; Abay, F.; Korkmaz, Y.N. Evaluation of mandibular osseous structure in patients with mandibular asymmetry: A fractal analysis study. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. 2023, 136, 656–662. [Google Scholar] [PubMed]
  36. Kang, D.; Kwak, K.H.; Kim, S.S.; Park, S.B.; Son, W.S.; Kim, Y.I. Application of fractal analysis of the midpalatal suture for estimation of pubertal growth spurts. Oral Radiol. 2017, 33, 199–203. [Google Scholar] [CrossRef]
  37. Arsan, B.; Köse, T.E.; Çene, E.; Özcan, İ. Assessment of the trabecular structure of mandibular condyles in patients with temporomandibular disorders using fractal analysis. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. 2017, 123, 382–391. [Google Scholar] [CrossRef]
  38. Türkmenoğlu, A.; Yüksel, H.T.; Karahan, A.Y. Evaluation of mandibular condyle trabecular structure in patients with rheumatoid arthritis using fractal analysis. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. 2022, 133, 229–237. [Google Scholar] [CrossRef]
  39. Yeşiltepe, S.; Yılmaz, A.B.; Kurtuldu, E.; Sarıca, İ. Fractal Analysis of Temporomandibular Joint Trabecular Bone Structure in Patients with Rheumatoid Arthritis on Cone Beam Computed Tomography Images. Meandros Med. Dent. J. 2018, 19, 345–351. [Google Scholar] [CrossRef]
  40. Günaçar, D.N.; Yemenoǧlu, H.; Ustaoǧlu, G.; Ariöz, Ö. Effects of hyperlipidemia on trabecular and cortical structures of the mandible. Dentomaxillofac. Radiol. 2022, 51, 20210214. [Google Scholar]
  41. Pantoja, L.L.Q.; Lustosa, M.; Yamaguti, P.M.; Rosa, L.S.; Leite, A.F.; Figueiredo, P.T.S.; Castro, L.C.; Acevedo, A.C. Pamidronate Therapy Increases Trabecular Bone Complexity of Mandibular Condyles in Individuals with Osteogenesis Imperfecta. Calcif. Tissue Int. 2022, 110, 303–312. [Google Scholar] [CrossRef] [PubMed]
  42. Amuk, M.; Gul Amuk, N.; Yllmaz, S. Treatment and posttreatment effects of Herbst appliance therapy on trabecular structure of the mandible using fractal dimension analysis. Eur. J. Orthod. 2022, 44, 125–133. [Google Scholar] [CrossRef] [PubMed]
  43. Bolat Gümüş, E.; Yavuz, E.; Tufekci, C. Effects of functional orthopedic treatment on mandibular trabecular bone in class II patients using fractal analysis. J. Orofac. Orthop. 2023, 84, 155–164. [Google Scholar] [CrossRef]
  44. Ertugrul, B.Y.; Veli, İ. Evaluating the effects of orthodontic treatment with clear aligners and conventional brackets on mandibular condyle bone quality using fractal dimension analysis of panoramic radiographs. J. Stomatol. Oral Maxillofac. Surg. 2022, 123, 538–545. [Google Scholar]
  45. Korkmaz, Y.N.; Arslan, S. Evaluation of the trabecular structure of the mandibular condyles by fractal analysis in patients with different dentofacial skeletal patterns. Australas. Orthod. J. 2021, 37, 93–99. [Google Scholar]
  46. Gulec, M.; Tassoker, M.; Ozcan, S.; Orhan, K. Evaluation of the mandibular trabecular bone in patients with bruxism using fractal analysis. Oral Radiol. 2021, 37, 36–45. [Google Scholar] [CrossRef]
  47. Cesur, E.; Bayrak, S.; Kursun-Çakmak, E.S.; Arslan, C.; Köklü, A.; Orhan, K. Evaluating the effects of functional orthodontic treatment on mandibular osseous structure using fractal dimension analysis of dental panoramic radiographs. Angle Orthod. 2020, 90, 783–793. [Google Scholar] [CrossRef]
  48. Baksi, B.G.; Fidler, A. Fractal analysis of periapical bone from lossy compressed radiographs: A comparison of two lossy compression methods. J. Digit. Imaging 2011, 24, 993–998. [Google Scholar] [CrossRef]
  49. Shrout, M.K.; Farley, B.A.; Patt, S.M.; Potter, B.J.; Hildebolt, C.F.; Pilgram, T.K.; Yokoyama-Crothers, N.; Dotson, M.; Hauser, J.; Cohen, S.; et al. The Effect of Region of Interest Variations on Morphologic Operations Data and Gray-Level Values Extracted from Digitized Dental Radiographs. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endodontology 1999, 88, 636–639. [Google Scholar] [CrossRef]
  50. Pauwels, R.; Faruangsaeng, T.; Charoenkarn, T.; Ngonphloy, N.; Panmekiate, S. Effect of exposure parameters and voxel size on bone structure analysis in CBCT. Dentomaxillofac. Radiol. 2015, 44, 20150078. [Google Scholar] [CrossRef]
  51. Koyuncuoglu, G.; Bayrak, S.; Ugur-Aydin, Z.; Aren, G. Evaluation of the Effects of MTA Apexification and Regenerative Endodontic Therapy on Lesion Healing using Fractal Analysis: A Retrospective Study. Eur. J. Paediatr. Dent. 2024, 1–6. [Google Scholar] [CrossRef]
  52. Toghyani, S.; Nasseh, I.; Aoun, G.; Noujeim, M. Effect of image resolution and compression on fractal analysis of the periapical bone. Acta Inform. Medica 2019, 27, 167–170. [Google Scholar]
  53. Kün-Darbois, J.D.; Bertin, H.; Mouallem, G.; Corre, P.; Delabarde, T.; Chappard, D. Bone characteristics in condylar hyperplasia of the temporomandibular joint: A microcomputed tomography, histology, and Raman microspectrometry study. Int. J. Oral Maxillofac. Surg. 2023, 52, 543–552. [Google Scholar] [CrossRef] [PubMed]
  54. Vásquez, B.; Olate, S.; Cantín, M.; Sandoval, C.; del Sol, M.; de Moraes, M. Histomorphometric analysis of unilateral condylar hyperplasia in the temporomandibular joint: The value of the condylar layer and cartilage island. Int. J. Oral Maxillofac. Surg. 2017, 46, 861–866. [Google Scholar] [CrossRef]
  55. Eslami, B.; Behnia, H.; Javadi, H.; Khiabani, K.S.; Saffar, A.S. Histopathologic comparison of normal and hyperplastic condyles. Oral Surg. Oral Med. Oral Pathol. Oral Radiol. Endodontology 2003, 96, 711–717. [Google Scholar]
Applsci 15 04063 g001
Figure 1. Selection of the three regions of interest on CBCT images. (a) coronal plane: on the superior half portion of the condyle (30 × 30 pixels); (b) axial plane: on the superior half of the condyle (35 × 15 pixels); (c) sagittal plane: on the superior half portion of the condyle (20 × 20 pixels).
Figure 1. Selection of the three regions of interest on CBCT images. (a) coronal plane: on the superior half portion of the condyle (30 × 30 pixels); (b) axial plane: on the superior half of the condyle (35 × 15 pixels); (c) sagittal plane: on the superior half portion of the condyle (20 × 20 pixels).
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Applsci 15 04063 g002
Figure 2. Fractal dimension processing. (a) cropped and duplicated image; (b) Gaussian blurred; (c) subtraction of the blurred image from the original image; (d) addition of 128 grayscale value; (e) binarization; (f) erosion; (g) dilation; (h) inversion; (i) skeletonization.
Figure 2. Fractal dimension processing. (a) cropped and duplicated image; (b) Gaussian blurred; (c) subtraction of the blurred image from the original image; (d) addition of 128 grayscale value; (e) binarization; (f) erosion; (g) dilation; (h) inversion; (i) skeletonization.
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Table 1. Mean values of fractal dimensions.
Table 1. Mean values of fractal dimensions.
GroupPlaneCondyleFractal
Dimension		Paired Differencesp-Value
MeanS.D.95% Confidence Interval of Difference
MeanS.D.LowerUpper
Asymmetrical patients
(n = 15)		AxialHyperplastic1.2150.0360.0650.0610.0320.0990.001 *
Contralateral1.1500.069
CoronalHyperplastic1.4130.0580.0650.0630.0300.0990.001 *
Contralateral1.3480.089
SagittalHyperplastic1.1270.0740.0510.115−0.0130.1150.110
Contralateral1.0770.086
Symmetrical patients
(n = 15)		AxialRight1.1900.0930.0140.106−0.0450.0730.626
Left1.1770.063
CoronalRight1.3730.1150.0090.134−0.0650.0830.793
Left1.3640.121
SagittalRight1.1770.1810.0370.155−0.0490.0220.735
Left1.1400.089
n: sample size; S.D. standard deviation; * Wilcoxon test: p-value < 0.05 indicates statistical significance.
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MDPI and ACS Style

De Stefano, A.A.; Musone, L.; Horodynski, M.; Vernucci, R.A.; Galluccio, G. Fractal Dimension of the Condylar Bone Structure in Patients with Unilateral Condylar Hyperplasia: Cross-Sectional Retrospective Study. Appl. Sci. 2025, 15, 4063. https://doi.org/10.3390/app15074063

AMA Style

De Stefano AA, Musone L, Horodynski M, Vernucci RA, Galluccio G. Fractal Dimension of the Condylar Bone Structure in Patients with Unilateral Condylar Hyperplasia: Cross-Sectional Retrospective Study. Applied Sciences. 2025; 15(7):4063. https://doi.org/10.3390/app15074063

Chicago/Turabian Style

De Stefano, Adriana Assunta, Ludovica Musone, Martina Horodynski, Roberto Antonio Vernucci, and Gabriella Galluccio. 2025. "Fractal Dimension of the Condylar Bone Structure in Patients with Unilateral Condylar Hyperplasia: Cross-Sectional Retrospective Study" Applied Sciences 15, no. 7: 4063. https://doi.org/10.3390/app15074063

APA Style

De Stefano, A. A., Musone, L., Horodynski, M., Vernucci, R. A., & Galluccio, G. (2025). Fractal Dimension of the Condylar Bone Structure in Patients with Unilateral Condylar Hyperplasia: Cross-Sectional Retrospective Study. Applied Sciences, 15(7), 4063. https://doi.org/10.3390/app15074063

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