Comparison of Decompression vs Enucleation Using Fractal Analysis with Panoramic Radiography for Odontogenic Cysts

Introduction

Odontogenic cysts are pathological bone cavities lined with epithelium and filled with fluid or empty, resulting from the proliferation and/or degeneration of epithelial residues remaining from the tooth development process [1,2]. The basis for the growth and expansion of odontogenic cysts is the increased osmotic and hydrostatic pressure within the cystic lumen, which increases osteoclastic resorption in the surrounding bone [3]. The incidence of odontogenic cysts varies depending on the type of cyst. In general, odontogenic cysts are among the most common lesions in the jaw region and are detected during routine dental examinations, as most are asymptomatic [4]. Radicular cysts are the most common odontogenic cysts in the literature; they constitute approximately 60% of all odontogenic cysts and are mostly found in the maxilla [5]. Approximately 5% of all odontogenic cysts are residual cysts, while dentigerous cysts constitute 20.6% of all odontogenic cysts [6]. In addition, dentigerous cysts account for 20% of cysts in the mandible [7]. Odontogenic keratocysts constitute 4% to 12% of all odontogenic cysts [6]. The choice of treatment for jaw cysts is influenced by the lesion’s biological characteristics and its location relative to critical anatomical structures [8,9]. The most commonly recommended treatments of odontogenic cysts are enucleation, marsupialization, and decompression [10]. In cases where simple enucleation can lead to various difficulties, such as damage to important anatomical structures like the inferior alveolaris or mental nerve during instrumentation, minimal invasive techniques, including decompression and marsupialization, can be used [11]. Decompression is a treatment for odontogenic cysts that aims to reduce the volume occupied by the cyst space by reducing the internal pressure through a catheter or stent placed in the cystic lumen [12]. Numerous studies have investigated the reduction rate of cystic defects following decompression, yielding varying outcomes, but they collectively show the effectiveness of this approach in significantly diminishing the cystic cavity, but these methods have disadvantages such as long treatment period and need for regular follow-up, and patient compliance is required. However, the entire lesion cannot be examined histopathologically [13–15]. Determining the optimal treatment method for odontogenic cysts can provide better clinical outcomes and more efficient health management for patients.

Fractal analysis (FA) is a mathematical method that can evaluate irregular and complex body structures. In dentistry, evaluation of the bone structure of the jaws in dental radiographs is the main result evaluated using FA [16,17]. FA helps evaluate osteoporosis, implant stability, and pathological bone changes by measuring the complexity of trabecular bone structures [18]. FA also detects mechanical properties of cortical bone such as elasticity and strength, making it an important tool for assessing fracture resistance [19]. Researchers investigating bone mineral density have also used this method for quantitative evaluation of trabecular bone [16,17]. Some studies have shown that FA can show the microarchitecture of trabecular bone and is a non-invasive method to detect and quantify changes in alveolar process bone mineral content [20,21]. The most innovative aspect of FA is its ability to quantitatively assess the healing process, unlike traditional radiographic assessments. This method provides clinicians with more reliable data by precisely measuring changes in bone microarchitecture [22,23]. This allows the effectiveness of different treatment approaches, such as enucleation and decompression, to be compared more objectively. Potential contributions of FA to clinical practice include the creation of individualized treatment plans, better estimation of patient prognosis, and prevention of unnecessary surgical interventions [22,23]. Radiographic examination plays an important role in diagnosis, treatment planning, and post-treatment evaluation. Generally, panoramic radiography (OPG), computed tomography (CT) scan, magnetic resonance imaging (MRI), and cone beam computed tomography (CBCT) scan can be used for radiographic examination of suspicious lesions in the jaws [24,25].

Although there are studies in the literature comparing the reduction rates of cyst volume with decompression versus enucleation, no definitive conclusion has been reached regarding the effects of these 2 methods on bone regeneration [26,27]. Assessing these reduction rates could provide valuable insights into the regenerative potential and relative advantages of these treatment methods. Odontogenic cysts are often asymptomatic, but if detected late, they can lead to serious complications. In this study, we aimed to determine which treatment method provides better bone healing.

Wer quantitatively compared changes in the bone trabecular structure of odontogenic cysts treated with enucleation versus decompression using FA. Our results may contribute to clinical practice by revealing whether FA is a more sensitive and objective indicator of healing than traditional radiographic evaluations. It is thought that this method offers an important innovation in terms of monitoring the healing process and optimizing the treatment selection in treatment of odontogenic cysts. Therefore, this retrospective study of 37 patients with odontogenic cysts aimed to compare outcomes from treatment by decompression versus enucleation, including the degree of trabeculation, evaluated by FA using OPG.

Material and Methods

STUDY DESIGN:

The study was conducted using a retrospective analysis of radiological data. All surgical procedures, imaging, and evaluations were performed at the Department of Oral and Maxillofacial Surgery, Eskişehir Osmangazi University. Ethics approval was obtained from the Eskişehir Osmangazi University Non-Interventional Clinical Research Ethics Committee (Decision no: 30, dated 19.03.2024), and the study adhered to the principles of the Declaration of Helsinki. Participants and/or their parents were informed verbally and in writing about the purpose and method of the study, and signed consent forms were obtained.

SAMPLE SIZE:

The required sample size calculation was made using G*Power 3.1.9.4 software. The 2-tailed t test was selected to compare the means of 2 independent groups. In the calculation, the effect size (Cohen’s d) was 1.2, α error probability 0.05, and power (1-β) 0.90, with 16 patients in each group. The required sample sizes for decompression and enucleation were calculated as 21 and 16, respectively, and a total of 37 samples were included in the study.

INCLUSION AND EXCLUSION CRITERIA:

The selection criteria included patients diagnosed with odontogenic cysts who had undergone either decompression or enucleation treatment between 2012 and 2024. Inclusion criteria were: patients without systemic diseases affecting bone metabolism, those not using medications related to bone metabolism, patients with no regular-use medications, and patients with no history of craniofacial syndromes or traumatic injuries. Patients with systemic diseases and those whose radiological archive records containing artifacts or that were too damaged to allow digital measurement were excluded from the study.

SURGICAL TECHNIQUE:

Surgical procedures were performed under local anesthesia using articaine hydrochloride with epinephrine. Enucleation was performed by raising a full-thickness mucoperiosteal flap, conducting an osteotomy with a round bur under continuous saline irrigation, and carefully removing the cystic lining with periosteal elevators to prevent tearing. The surgical site was sutured with 3-0 silk sutures and hemostasis was ensured. The specimen was submitted for histopathological analysis to establish a diagnosis. For decompression, a similar approach was used, but instead of complete removal, a small osteotomy was created for insertion of a decompression stent. Nelaton catheters (sizes 12 and 14) were trimmed to appropriate lengths and sutured into place with 3-0 silk sutures (Figure 1). Patients were instructed to irrigate the cystic cavity with sterile saline solution daily using a 10-ml syringe, and bi-weekly follow-ups ensured catheter patency and monitored healing progression. Cysts that received decompression were fully enucleated following different intervals, based on the extent of cystic cavity reduction. A course of medication following surgery was routinely given after treatment with enucleation and decompression. This regimen included antibiotics, nonsteroidal anti-inflammatory tablets, and mouthwash.

FOLLOW-UP PERIOD:

Patients were followed up with OPG taken at 3 (T1) and 6 (T2) months after surgery.

RADIOLOGIC ANALYSIS:

Dental panoramic radiographs were utilized to evaluate bone healing, ensuring consistency by using the same technician and equipment in accordance with the manufacturer’s guidelines (Planmeca Promax; Planmeca, Helsinki, Finland; 65 kVp, 6 mA, 16 s exposure time). Patient positioning was standardized, with the Frankfurt horizontal plane aligned parallel to the ground.

High-resolution JPEG format periapical radiographs included in the study were converted to TIFF format for analysis. FA calculations were performed using ImageJ software (v.1.54; Wayne Rasband and contributors, National Institutes of Health, USA). The box-counting method described by White and Rudolph [28] was employed for FA. Regions of interest (ROI) were selected from the panoramic images, centered on the cyst region, with a defined size of 50×30 pixels. The ROI was cropped and duplicated for further processing (Figure 2). A Gaussian filter (σ=35) was applied to minimize brightness variations caused by soft tissue and differing bone thicknesses. The resulting blurred image was subtracted from the original image, and grayscale levels were adjusted to 128 shades per pixel. The image underwent thresholding to limit pixel values to between 0 and 128. Subsequently, the image was converted to binary (black and white) to differentiate between trabecular bone and bone marrow. Noise reduction was achieved by applying erosion followed by dilation. The black regions were inverted to white, highlighting the trabecular bone outlines. These outlines were traced to create a mesh-like structure suitable for FA. Using the “fractal box counting” function in ImageJ, the images were divided into grid sizes ranging from 2 to 64 pixels, and the software calculated the FA value for each image. The measurements were repeated for the same ROI on both the cyst and healthy sides of the patient across all imaging stages. Bone structural changes were analyzed using FA at 3 time points: preoperatively (T0), 3 months postoperatively (T1), and 6 months postoperatively (T2). The central area of the cyst served as the focus for FA at each time point. Image analyses were performed by a single observer. To evaluate intraobserver reliability, images from 10 randomly selected patients were reassessed after a 2-week interval. Pearson correlation coefficients were calculated to assess measurement consistency. No statistically significant differences were observed between the initial and repeated measurements (P>0.05), indicating consistent results.

STATISTICAL ANALYSIS:

Statistical analysis was performed using SPSS version 22.0 (IBM, Chicago, USA). Normality was tested using the Shapiro-Wilk test. Continuous variables were compared between groups using the Mann-Whitney U test and t test, as appropriate. The significance level set at P<0.05. Descriptive statistics, including means, standard deviations, and confidence intervals, were reported for all measured variables.

Results

Thirty-seven patients aged 7–82 years (mean age 30.43±17.8) were included in the study; 21 (56.8%) patients were treated with decompression and 16 (43.2%) patients were treated with enucleation; 16 (43.2%) treated patients were female and 21 (56.8%) were male. Among females, 10 (62.5%) were treated with decompression, while 6 (37.5%) were treated with enucleation. Among males, 11 (52.4%) were treated with decompression, while 10 (47.6%) were treated with enucleation. The mean FA of the cysts before treatment was 0.97. The mean FA values at 3 and 6 months after the operation were 1.09 and 1.20, respectively (Table 1). Descriptive statistics of preoperative, postoperative 3rd month and postoperative 6th month FA for treatment groups are shown in Table 2. The mean age of patients treated with decompression was 25.81 years. Preoperative, postoperative 3rd month, and postoperative 6th month mean FA values were 0.97, 1.09, and 1.20, respectively. The mean age of patients treated with enucleation was 36.50 years. Preoperative, postoperative 3rd month, and postoperative 6th month mean FA values were 0.96, 1.12, and 1.25, respectively (Table 2). When the change in FA between the measurement times (Table 3) was compared between the treatment groups, no statistically significant difference was found (P>0.05).

Discussion

The findings of this study indicate that decompression and enucleation are both effective treatment modalities for odontogenic cysts, as evidenced by the increase in FA values over time. This suggest that bone regeneration occurs following both treatment methods. However, no statistically significant difference was observed between the 2 approaches at the 3rd and the 6th postoperative months.

The literature shows that the average age of occurrence of odontogenic cysts is in the 2nd and 3rd decades [29]. In our study, it was seen in the 3rd decade on average, which is consistent with the literature. However, when sex distribution was examined, cysts were predominantly seen in females [30]. In our study, contrary to the literature, odontogenic cysts were seen more frequently in male patients. This difference is thought to vary depending on the sample size and local population.

When odontogenic cysts are located near critical anatomical structures, the primary focus is to safeguard these structures. Therefore, before treatment with enucleation, decompression and marsupialization, which are minimally invasive methods, can be applied [31]. The marsupialization method applied in the treatment of odontogenic cysts reduces the risk of complications in treatment of large-sized odontogenic cysts and also aids the spontaneous eruption of impacted teeth associated with the cyst [32]. Marsupialization and decompression treatments have advantages such as gradual reduction of the cystic space, maintaining tooth vitality, avoiding tooth extraction, protecting the inferior alveolar nerve, preventing oroantral and oronasal communication, and safeguarding against mandibular fractures [33]. Park et al [9] stated that the enucleation technique should be applied until the lesion size is expected to be reduced enough to not harm the anatomical structure. Zhao and Kubota et al reported that lesions treated with marsupialization exhibited more rapid shrinkage in larger cysts compared to smaller ones [34,35]. Similarly, in a 12-month follow-up study comparing the monthly shrinkage rates of cysts in the enucleation and marsupialization groups in millimeters, Demir et al found a faster improvement in the marsupialization group, but this did not reach statistical significance [27]. In a study conducted by Dereci et al [26] on 30 patients through two-dimensional measurements of cyst size, both the enucleation and marsupialization groups showed notable improvement over time, although the difference in improvement between the 2 methods was not statistically significant. There was no significant difference in the groups that underwent decompression and marsupialization at 3 and 6 months. This shows that treatment with marsupialization is as successful as treatment with enucleation.

FA is widely used in the medical field and has also begun to be used in dentistry. It is especially used in the analysis of bone structures in dental radiographs [36]. It has been used in the literature to evaluate trabecular changes in osteoporosis patients. With this method, bone mineral density is evaluated, and it is becoming a standard method [37]. Rising FA values are linked to the complexity of the bone structure and the process of new bone formation [38]. Ozturk et al [23] examined the ROI taken from the centers of cysts in their study on children and reported that FA increased quantitatively over time and that increasing FA values were related to the complexity of the bone structure and new bone formation. These results also showed that the FA method can be applied to cysts. It has been noted that changes in FA should be corroborated by clinical findings for accurate assessment. In the study, in addition to radiographic findings, intraoral and extraoral clinical findings of the patients were also carefully monitored [23]. Kaygısız et al [22] also treated odontogenic cysts with marsupialization and enucleation. They reported that the degree of trabeculation in lesions treated with marsupialization was comparable to those treated with enucleation. However, since the lesions in the marsupialization group were significantly larger, the marsupialization technique demonstrated a quicker healing response. We also used fractal analysis (FA) method, which is an important measurement method in terms of standardization of measurements and data objectivity. In this study, the notable rise in fractal dimension (FD) values at the 3rd and 6th months provides a quantitative indication of changes in the bone structure.

The study limitations include the relatively small sample size, which may have affected the statistical power, potentially limiting the generalizability of the findings. Additionally, the follow-up period of 6 months may not have been sufficient to fully capture long-term bone regeneration patterns. A longer follow-up period is necessary to determine whether the observed trends in FA changes persist over time. Another limitation pertains to the inherent challenges of using OPG for FA, as artifacts and variations in image quality can influence FA calculations. Moreover, patient compliance with decompression therapy, including regular irrigation and follow-up visits, could affect healing outcomes but was not extensively evaluated in this study. In particular, there may be structures in the cystic area and symmetrical areas that prevent FA measurements, such as teeth, mental nerve, and alveolaris inferior nerve.

Conclusions

This study demonstrates that the FA method is applicable and reliable for evaluating bone healing in cystic regions. The significant increase in FA values at 3 and 6 months postoperatively confirms its effectiveness in assessing trabecular changes. The results indicate that marsupialization and enucleation lead to similar degrees of trabecular bone regeneration over time, as evidenced by the FA values (T0: 0.97, T1: 1.09, T2: 1.20 for decompression; T0: 0.96, T1: 1.12, T2: 1.25 for enucleation). These findings suggest that both techniques can be considered effective treatment modalities in clinical practice. The similarity in trabecular regeneration between the 2 techniques implies that treatment choice should be guided by anatomical considerations, cyst size, and patient-specific factors rather than a presumed superiority of one method over the other. This has important implications for clinical decision-making, as it highlights that marsupialization can be a viable alternative in cases where enucleation poses risks to critical anatomical structures. While previous studies have compared decompression and enucleation regarding cyst volume reduction, research on their effects on bone healing using FA remains limited. This study contributes to the field by providing quantitative evidence of trabecular changes over time, offering a more objective assessment than conventional radiographic evaluations. By demonstrating the applicability of FA in cyst healing, our findings establish a foundation for further research and clinical use of this technique. Future studies should focus on long-term follow-ups to assess whether the observed trends in FA values persist beyond 6 months. Additionally, research incorporating advanced imaging techniques such as OPG could provide a more detailed understanding of trabecular bone regeneration patterns. Investigating patient-specific factors, such as age, systemic conditions, and compliance with decompression therapy, could further refine treatment protocols for odontogenic cysts. By addressing these aspects, this study not only supports the reliability of FA in cystic regions but also provides a framework for future investigations aimed at optimizing cyst treatment strategies.