Radicular Cysts Research Articles

Notch-1/2 receptors and Jagged-1 ligand, but not HERP-1 transcription factor, are immunohistochemically expressed in the epithelial lining of periapical cysts.

To further understand the involvement of Notch pathway signaling in the pathogenesis of periapical cyst the immunohistochemical expression of Notch-1 and Notch-2 receptors, Jagged-1 ligand, and HERP-1 transcription factor in the lining epithelium of periapical cysts was investigated. Thirty human periapical cysts were immunohistochemically stained with antibodies against Notch-1, Notch-2, Jagged-1, and HERP-1. Epithelial expression of each antibody was correlated with the presence of inflammation in the connective tissue of the cystic wall. Notch-1 was identified in the basal and suprabasal epithelial cells of 30/30, Notch-2 in 19/24, and Jagged-1 in 27/30 cysts. HERP-1 was detected in scattered subepithelial inflammatory cells, but not in the lining epithelium of cysts. There was no significant correlation between the immunohistochemical expression of each antibody and the presence of inflammation in the connective tissue of the cystic wall. This immunohistochemical study showed expression of Notch-1/2 and Jagged-1 in periapical cysts that combined with the expression of HES1/5 found in a previous report, are indicative of the activation of Notch an endocrine-paracrine mechanism. Further research on the activity of Notch and other pathways in periapical cysts may contribute both to elucidate their pathogenesis and select molecular targets for future novel treatments. Key words:Odontogenic cyst, radicular cyst, etiology, epithelial cells, Notch, Jagged, HERP.

A Case of Respiratory Epithelium-Lined Cyst with Enriched Nociceptor Innervation

Apical lesions of endodontic origin can be classified as either granulomas or cysts. In rare cases, respiratory epithelium can proliferate and encapsulate a lesion, forming a cyst. Moreover, the innervation of apical lesions has only been previously reported in animal models of apical periodontitis. This report demonstrates an unusual case in which tooth #15 was initially treated with nonsurgical root canal therapy. Still, the patient remained in moderate to severe pain for several days following the procedure. Next, an intentional replantation was performed in which a periapical cyst was curetted from the alveolus. The patient experienced immediate pain relief following the procedure. Histological analysis revealed that the periapical cyst was lined entirely with respiratory epithelium, and immunohistochemical analysis showed it to be densely innervated. In addition, these nerve fibers expressed the LPS receptor, TLR4. This is the first demonstration of the innervation pattern of a periapical cyst. Further studies are warranted to evaluate innervation in apical lesions and its correlation with pre- and intra-operative symptoms and their participation in the pathogenesis of apical periodontitis.

Atypical Neurofibroma Masquerading an Odontogenic Cyst-A Case Report

Neurofibroma is a benign tumor characterized by perineural fibroblast proliferation. It is common in the head and neck region but rare in the oral cavity. Most of these lesions are asymptomatic but sometimes may be associated with pain and paraesthesia. Neurofibromas with atypical features are quite rare and only a few cases are reported in literature. Here is a case of a female patient presented with pain and swelling in the anterior maxilla, which was clinically diagnosed as a periapical cyst. Radiographic evaluation of the lesion revealed dilated incisive canal and a Nasopalatine duct cyst was suspected. The patient was advised to take antibiotics for one week. The symptoms were sustained in the follow-up visit and an incision biopsy was made. Microscopic examination revealed pleomorphic spindled and round cells. Immunohistochemistry was performed to identify the origin of these pleomorphic cells. Based on the histopathological examination, special staining, and immunohistochemistry, we concluded the diagnosis as neurofibroma with atypical features. The current case emphasizes the significance of clinical, radiological, histopathological, and immunohistochemical evaluation of oral lesions. The presence of atypical features in Neurofibroma must be considered cautiously as as it is more prone to progress into Malignant Peripheral Nerve Sheath Tumor (MPNST).

Expression of Fascin and SALL4 in odontogenic cysts and tumors: an immunohistochemical appraisal.

Various stemness markers (SOX2, OCT4, and NANOG) have been studied in odontogenic cysts and tumors. However, studies on SALL4 having similar properties of stemness has not been documented. Additionally, insight into fascin as a migratory molecule is less explored. In this study, the expression of SALL4 and fascin were evaluated in ameloblastoma, adenomatoid odontogenic tumor (AOT), odontogenic keratocyst (OKC), dentigerous cyst (DC), radicular cyst (RC), and calcifying odontogenic cyst (COC). Semi-quantitative analysis of fascin and SALL4 immuno-positive cells was done in a total of 40 cases of ameloblastoma (11 plexiform, 12 follicular, 12 unicystic, and 5 desmoplastic) variants, 6 cases of AOT, 15 each of OKC, DC, RC and 5 of COC. Chi-square test was applied to evaluate the association between SALL4 and fascin expression in odontogenic cysts and tumors. Fascin immunopositivity was observed in peripheral ameloblast-like cells, and the expression was weak or absent in stellate reticulum-like cells. A moderate to weak immune-reactivity to SALL4 was observed in the cytoplasm of ameloblastoma, epithelial cells of dentigerous and radicular cysts, having a marked inflammatory infiltrate, which was an interesting observation. COC and AOT had negative to weak expressions. No recurrence has been reported. Expression of fascin in ameloblastomas elucidate their role in motility and localized invasion. Its expression in less aggressive lesions like DC, COC, AOT will incite to explore the other functional properties of fascin. SALL4 expression in the cytoplasm of odontogenic cysts and tumors may represent inactive or mutant forms which requires further validation.

Detection and Segmentation of Radiolucent Lesions in the Lower Jaw on Panoramic Radiographs Using Deep Neural Networks.

Background and Objectives: The purpose of this study was to develop and evaluate a deep learning model capable of autonomously detecting and segmenting radiolucent lesions in the lower jaw by utilizing You Only Look Once (YOLO) v8. Materials and Methods: This study involved the analysis of 226 lesions present in panoramic radiographs captured between 2013 and 2023 at the Clinical Hospital Dubrava and the School of Dental Medicine, University of Zagreb. Panoramic radiographs included radiolucent lesions such as radicular cysts, ameloblastomas, odontogenic keratocysts (OKC), dentigerous cysts and residual cysts. To enhance the database, we applied techniques such as translation, scaling, rotation, horizontal flipping and mosaic effects. We have employed the deep neural network to tackle our detection and segmentation objectives. Also, to improve our model's generalization capabilities, we conducted five-fold cross-validation. The assessment of the model's performance was carried out through metrics like Intersection over Union (IoU), precision, recall and mean average precision (mAP)@50 and mAP@50-95. Results: In the detection task, the precision, recall, mAP@50 and mAP@50-95 scores without augmentation were recorded at 91.8%, 57.1%, 75.8% and 47.3%, while, with augmentation, were 95.2%, 94.4%, 97.5% and 68.7%, respectively. Similarly, in the segmentation task, the precision, recall, mAP@50 and mAP@50-95 values achieved without augmentation were 76%, 75.5%, 75.1% and 48.3%, respectively. Augmentation techniques led to an improvement of these scores to 100%, 94.5%, 96.6% and 72.2%. Conclusions: Our study confirmed that the model developed using the advanced YOLOv8 has the remarkable capability to automatically detect and segment radiolucent lesions in the mandible. With its continual evolution and integration into various medical fields, the deep learning model holds the potential to revolutionize patient care.

Immunohistochemical Comparison of Ki-67 and MCM-3 in Odontogenic Cysts: An Observational Study.

Odontogenic cysts are a diverse group of pathologic entities with different proliferation potential, leading to variations in their biological behavior. One of the most cited proliferation markers used in diagnostic histopathology is Ki-67. Another group of proteins recently investigated is minichromosome maintenance (MCM-3) and its expression has been evaluated in several odontogenic lesions but the results were controversial. Thus, the present study endeavored to compare the expression of MCM-3 and Ki-67 in odontogenic cysts. Furthermore, a pioneer attempt was made to evaluate the sensitivity of these markers to inflammation. A total of 101 cases (37 dentigerous cysts, 37 odontogenic keratocysts, and 27 radicular cysts) were included. Immunohistochemical expression of Ki-67 and MCM-3 were investigated using a labeling index (LI). In addition, they were scored for inflammation, followed by correlation with both markers. The data obtained were subjected to statistical analysis ( P <0.05). Overall, a higher LI of MCM-3 than Ki-67 was obtained in all study groups along with a positive correlation of Ki-67 LI with inflammation. Thus, MCM-3 proteins proved to be a more accurate means to determine the proliferation potential and were not sensitive to external stimuli like inflammation than conventional markers, such as Ki-67.

СОВРЕМЕННЫЙ ВЗГЛЯД НА ТЕОРИИ ПАТОГЕНЕЗА РАДИКУЛЯРНЫХ КИСТ (ОБЗОР ЛИТЕРАТУРЫ)

The subject. Radicular cyst is the most common type of odontogenic tumors of the jaws of inflammatory type, with an incidence of 52–68% of all diagnosed jaw cystic sacs. A review of literary sources in recent years related to the study of cystogenesis has revealed various concepts of the pathogenesis of this pathology. It does not allow us to identify a decisive theory for the development of radicular cysts that determines the beginning of its formation. &#x0D; Objectives. To study the features of the pathogenetic development of radicular cysts, according to the literature.&#x0D; Methodology. Within the framework of this article, the analysis of publications from the databases PubMed, Google, eLibrary and Cyberleninka. The search included full-text articles. The main selection of materials was carried out by keywords.&#x0D; Results. However, a significant portion of researchers believe that the cystogenesis of radicular cysts is a multifactorial, immunologically controlled process with a close functional relationship of all components, with the primary causative factor being bacterial invasion. Microorganisms localized inside the root canal initiate an immunopathological process, in response to which a tissue reaction is recorded in the form of chronic inflammation. Pathophysiological processes are controlled by flocogens. The regulation of them may go beyond their sequential coordination. As a rule, this leads to tissue damage, the product of which is pathological formations, including a radicular cyst. &#x0D; Conclusions. The article presents modern data on the key factors of cystogenesis – etiological, morphological in the context of the theory of cyst sacs as an immunologically controlled process.

Machine learning in the detection of dental cyst, tumor, and abscess lesions

Background and ObjectiveDental panoramic radiographs are utilized in computer-aided image analysis, which detects abnormal tissue masses by analyzing the produced image capacity to recognize patterns of intensity fluctuations. This is done to reduce the need for invasive biopsies for arriving to a diagnosis. The aim of the current study was to examine and compare the accuracy of several texture analysis techniques, such as Grey Level Run Length Matrix (GLRLM), Grey Level Co-occurrence Matrix (GLCM), and wavelet analysis in recognizing dental cyst, tumor, and abscess lesions.Materials & MethodsThe current retrospective study retrieved a total of 172 dental panoramic radiographs with lesion including dental cysts, tumors, or abscess. Radiographs that failed to meet technical criteria for diagnostic quality (such as significant overlap of teeth, a diffuse image, or distortion) were excluded from the sample. The methodology adopted in the study comprised of five stages. At first, the radiographs are improved, and the area of interest was segmented manually. A variety of feature extraction techniques, such GLCM, GLRLM, and the wavelet analysis were used to gather information from the area of interest. Later, the lesions were classified as a cyst, tumor, abscess, or using a support vector machine (SVM) classifier. Eventually, the data was transferred into a Microsoft Excel spreadsheet and statistical package for social sciences (SPSS) (version 21) was used to conduct the statistical analysis. Initially descriptive statistics were computed. For inferential analysis, statistical significance was determined by a p value < 0.05. The sensitivity, specificity, and accuracy were used to find the significant difference between assessed and actual diagnosis.ResultsThe findings demonstrate that 98% accuracy was achieved using GLCM, 91% accuracy using Wavelet analysis & 95% accuracy using GLRLM in distinguishing between dental cyst, tumor, and abscess lesions. The area under curve (AUC) number indicates that GLCM achieves a high degree of accuracy. The results achieved excellent accuracy (98%) using GLCM.ConclusionThe GLCM features can be used for further research. After improving the performance and training, it can support routine histological diagnosis and can assist the clinicians in arriving at accurate and spontaneous treatment plans.

Building Automation Pipeline for Diagnostic Classification of Sporadic Odontogenic Keratocysts and Non-Keratocysts Using Whole-Slide Images.

The microscopic diagnostic differentiation of odontogenic cysts from other cysts is intricate and may cause perplexity for both clinicians and pathologists. Of particular interest is the odontogenic keratocyst (OKC), a developmental cyst with unique histopathological and clinical characteristics. Nevertheless, what distinguishes this cyst is its aggressive nature and high tendency for recurrence. Clinicians encounter challenges in dealing with this frequently encountered jaw lesion, as there is no consensus on surgical treatment. Therefore, the accurate and early diagnosis of such cysts will benefit clinicians in terms of treatment management and spare subjects from the mental agony of suffering from aggressive OKCs, which impact their quality of life. The objective of this research is to develop an automated OKC diagnostic system that can function as a decision support tool for pathologists, whether they are working locally or remotely. This system will provide them with additional data and insights to enhance their decision-making abilities. This research aims to provide an automation pipeline to classify whole-slide images of OKCs and non-keratocysts (non-KCs: dentigerous and radicular cysts). OKC diagnosis and prognosis using the histopathological analysis of tissues using whole-slide images (WSIs) with a deep-learning approach is an emerging research area. WSIs have the unique advantage of magnifying tissues with high resolution without losing information. The contribution of this research is a novel, deep-learning-based, and efficient algorithm that reduces the trainable parameters and, in turn, the memory footprint. This is achieved using principal component analysis (PCA) and the ReliefF feature selection algorithm (ReliefF) in a convolutional neural network (CNN) named P-C-ReliefF. The proposed model reduces the trainable parameters compared to standard CNN, achieving 97% classification accuracy.

Periapical Cyst Forming Cutaneous Sinus Tract: Unusual Presentation-Case Report.

A cutaneous sinus tract due to periapical cyst being very rare may easily be misdiagnosed, leading to incorrect treatment. Identifying the etiology is difficult, but it is the key to effective therapy. The case presented here is a cutaneous sinus tract in the nasolabial region of odontogenic origin. After surgery and extraction of the tooth, the sinus tract healed remarkably (Belmehdi et al. in Contemp Clin Dent 9:314-318, 2018; Latifa et al. in Clin Case Rep 10:e05333, 2022).

Design An Intelligent System to Support Dental Cyst Detection Using Two Convolutional Neural Networks

The aim of this paper is to develop a methodology, through studies on Computer Vision techniques, for the automatic identification of dental cysts in panoramic radiography images, providing Dental professionals with an alternative aid in the interpretation of these images. In addition segmentation techniques are applied in the inner region of the jaws, seeking to separate the regions with a greater possibility of cyst. The objective of this work is to design an intelligent system that supports the diagnosis of Dental Cyst using convolutional neural networks in order to help detect Dental Cyst at an early stage. The research method applied in this study consists of model design, where built and trained two convolutional neural network architectures, supporting 80% of the dataset with a total of 775 images with four image categories, and proposal validation, where we work with the remaining 20% of the dataset. Our results show that the ResNet50 architecture achieved the best classification with an accuracy of 98%.

Dental and jawbone abnormalities linked to amelogenesis imperfecta: A retrospective and analytic study comparing panoramic radiographs.

Amelogenesis Imperfecta (AI) is a disorder of tooth development characterized by abnormal enamel formation. In order to detect other dental and jawbone abnormalities that could be associated with AI, a retrospective and analytic study was conducted comparing panoramic radiographs of AI and non-AI patients. Digital panoramic radiographs of 60 AI and 60 non-AI patients were examined. Abnormalities in dental number, size, shape, eruption, and in the shape of the dental arches were checked and blindly recorded by two experimented observers. Descriptive statistics using percentages and chi-square test with .05 level of significance value was used. Prevalence of supernumerary teeth, dental agenesis, microdontia, taurodontism, radicular dilacerations, dental inclusions, temporary teeth persistence, and pulp calcifications was significantly higher in AI patients compared to control patients. Prevalence of periapical images, cysts, and hypercementosis was lower in AI patients compared to control patients, with no statistically significant difference. A significant prevalence of mandibular hypoplasia was also noted in AI patients. In addition to enamel defect, panoramic radiography was useful in detecting other dental abnormalities and mandibular hypoplasia associated with AI and should therefore be systematically indicated for AI patients' care.

Automatic detection and classification of nasopalatine duct cyst and periapical cyst on panoramic radiographs using deep convolutional neural networks

The aim of this study was to evaluate a deep convolutional neural network (DCNN) method for the detection and classification of nasopalatine duct cysts (NPDC) and periapical cysts (PAC) on panoramic radiographs. A total of 1,209 panoramic radiographs with 606 NPDC and 603 PAC were labeled with a bounding box and divided into training, validation, and test sets with an 8:1:1 ratio. The networks used were EfficientDet-D3, Faster R-CNN, YOLO v5, RetinaNet, and SSD. Mean average precision (mAP) was used to assess performance. Sixty images with no lesion in the anterior maxilla were added to the previous test set and were tested on 2 dentists with no training in radiology (GP) and on EfficientDet-D3. The performances were comparatively examined. The mAP for each DCNN was EfficientDet-D3 93.8%, Faster R-CNN 90.8%, YOLO v5 89.5%, RetinaNet 79.4%, and SSD 60.9%. The classification performance of EfficientDet-D3 was higher than that of the GPs' with accuracy, sensitivity, specificity, positive predictive value, and negative predictive value of 94.4%, 94.4%, 97.2%, 94.6%, and 97.2%, respectively. The proposed method achieved high performance for the detection and classification of NPDC and PAC compared with the GPs and presented promising prospects for clinical application.

Radicular Cyst: A Cystic Lesion Involving the Hard Palate

Radicular Cyst: A Cystic Lesion Involving the Hard Palate

Case Report: Introduction of antibiotic releasing calcium sulfate bone void filler beads (Stimulan) for management of an infected cyst of the maxilla

Radicular cysts are the most common odontogenic cyst arising from epithelial cell rests of Malassez in the periodontal ligament and proliferate peripherally as a result of inflammation caused by infection at the root apices. They slowly grow apically causing bone resorption and displacement of the adjacent teeth which radiographically is seen as a radiolucent unilocular lesion. Management of such bone defects can be done by using various bone graft substitutes such as autogenous, allografts, xenografts and alloplasts. Taking account of the benefits of using synthetic bone graft substitutes, the following case represents the successful management of a radicular cyst, which includes endodontic treatment and cyst enucleation, chemical cauterization followed by introduction of antibiotic (Vancomycin) releasing calcium sulfate filler beads into the defect.

Cone-beam CT imaging features of common cystic lesions associated with the impacted mandibular third molar

Objective: To analyze the imaging features of cone-beam CT (CBCT) of ameloblastoma (AB), odontogenic keratocyst (OKC) and dentigerous cysts (DC) associated with the mandibular impacted third molars,so as to provide useful information for differential diagnosis of these lesions. Methods: The patients who were with complete clinical data, pathological diagnosis and CBCT images from AB, OKC and DC around the mandibular impacted third molars were collected in Peking University Hospital of Stomatology from August 2016 to December 2021. A total of 109 patients (14 were diagnosed as AB, 23 were diagnosed as OKC and the others were diagnosed as dental cysts) were collected, including 73 males and 36 females. The age ranged from 11 to 70. The analyzed imaging features included location and internal density of the lesions, bone expansion, root resorption of adjacent teeth and types of the impacted teeth. The Chi square test was used to compare the gender of different lesions, and the Fisher's exact test was used to compare imaging features of lesions. When P<0.05, there was a significant difference among the three. Logistic regression analysis was performed to determine the imaging features that significantly contribute to correct imaging diagnosis. Corresponding P-values were calculated for all factors from multivariate models. Results: In the 23 cases of OKC, no special location was observed for the center of the lesion, heterogeneous high-density were seen in 21.7% of the cases, 56.5% of the cases had no significant bone expansion and the impacted teeth were not specially oriented. Among the 14 AB, 7 cases (7/14) were mainly located in the ramus of the mandible, and all cases (14/14) had buccal/lingual expansion of the jaw, 8 cases (8/14) presented root resorption of the adjacent teeth, and mesial impacted mandibular third molar were seen in 6 cases (6/14). Among the 72 DC, 88.9% (64/72) of the cases were mainly limited to the crown of the impacted third molar, 72.2% (52/72) of the cases had no obvious bone expansion, inverted impacted teeth were shown in 56.9% (41/72) of the cases. There was a significant difference among the three groups (χ2=7.30, P=0.026) in gender. AB and odontogenic cyst were more common in men than in women, while the incidence of OKC was roughly equal between men and women.There were significant differences in the location (P<0.001), internal density (P=0.001) of the lesions, bone expansion (P<0.001) and types of the impacted teeth (P<0.001), while no statistical difference was found for root resorption of adjacent teeth (P=0.153). Logistics regression analysis showed that the location of the lesion, internal density, bone expansion, root resorption of adjacent teeth and the types of impacted teeth had significant effects on the accurate diagnosis of the three kinds of lesions. Conclusions: Location, internal density, bone expansion and types of the impacted teeth played an important role in the correct imaging diagnosis. Further analysis indicates that when the classification of impacted teeth and the location of lesions are considered synchronously, DC can be differentiated from AB and OKC.

Expression of Fascin and SALL4 in odontogenic cysts and tumors: an immunohistochemical appraisal.

Background: Various stemness markers (SOX2, OCT4, and NANOG) have been studied in odontogenic cysts and tumors. However, studies on SALL4 having similar properties of stemness has not been documented. Additionally, insight into fascin as a migratory molecule is less explored. Following a thorough literature search we hypothesize that fascin might contribute for the local migratory behaviour of the odontogenic epithelial cells in tumors and cysts while SALL4 may contribute to stemness property. Thus, the aim of the present study was to evaluate the expression of fascin and SALL4 in histopathological variants of Ameloblastoma, Adenomatoid Odontogenic Tumor (AOT) and various odontogenic cysts namely Odontogenic keratocyst (OKC), Dentigerous cyst (DC), Radicular cyst (RC), and Calcifying odontogenic cyst (COC). Methods: Semi-quantitative analysis of fascin and SALL4 immuno-positive cells was evaluated in a total of 40 cases of ameloblastoma (11 plexiform, 12 follicular, 12 unicystic, and 5 desmoplastic) variants, 6 cases of AOT, 15 cases each of OKC, DC, RC and 5 of COC. Chi-square test was applied to evaluate the association between SALL4 and fascin expression in odontogenic cysts and tumors. Results: Fascin immunopositivity was observed in peripheral ameloblast-like cells, and the expression was weak or absent in stellate reticulum-like cells. A moderate to weak immune-reactivity to SALL4 was observed in the cytoplasm of ameloblastoma, epithelial cells of DC and RC having a marked inflammatory infiltrate, which was an interesting observation. COC and AOT had negative to weak expressions. Conclusion: Expression of fascin in ameloblastomas elucidate their role in motility and localized invasion. Its expression in less aggressive lesions like DC, COC, AOT will incite to explore the other functional properties of fascin. SALL4 expression in the cytoplasm of odontogenic cysts and tumors may represent inactive or mutant forms which requires further validation.

Platelet Rich Plasma (PRP) Augmentation: A Novel Approach in Management of Radicular Cyst Present at Different Locations within Jaw: A Case Series

Periapical cysts are inflammatory cysts that developed due to caries and trauma of the involved tooth. Usually, the tooth becomes nonvital with pain, swelling, and sinus formation. On radiographic examination these cyst shows radiolucency around the apex of the involved tooth. On aspiration straw colored inflammatory fluid with or without pus comes out suggestive of a radicular cyst. Surgical removal with curettage of the lesion, apicoectomy, and root canal treatment should be performed to treat the lesion. Excised cavity can be augmented with PRP (Platelet rich plasma) or PRF (Platelet rich fibrin) for better healing of the lesion. This case series reported 3 such cases and their treatment with follow-up.

Conservative endodontic microsurgery to protect critical anatomical structures–selective curettage: a case series

BackgroundEndodontic microsurgery has yielded highly successful outcomes in preserving teeth with persistent or recurrent cases of periapical periodontitis that could not be successfully treated by nonsurgical endodontic approaches. To avoid complications in conditions in which periapical lesions invade anatomical structures such as the nasopalatine nerve tube and mandibular canal, selective curettage has been proposed as an alternative choice of complete curettage in surgery.Case presentationThe 8 cases reported herein had undergone root canal treatment and/or retreatment but still presented with symptoms, such as recurring sinus tracts and persistent dull pain. The radiographic examination indicated a large area of radiolucency that was associated with the tooth and had invaded adjacent critical anatomical structures. The patients opted for selective curettage via endodontic microsurgery, and the lesions were histologically confirmed as periapical cysts or granulomas. The follow-up results for one year or more indicated that the affected teeth were clinically asymptomatic and exhibited complete or incomplete healing radiographically.ConclusionThis case series provides clinical evidence for the feasibility of selective curettage in endodontic microsurgery, which can avoid complications caused by damage to the adjacent critical anatomical structures.

Mesenchymal Stem Cells Derived from Human Periapical Cysts and Their Implications in Regenerative Medicine.

Mesenchymal stem cells currently play an important role in the tissue engineering field in developing new regenerative approaches. The oral cavity is a rich source of mesenchymal stem cells, and introducing the use of dental stem cells, characterized by a multilineage differentiation potential, immunomodulatory activity and repair capacity, offers a good perspective for clinical dentistry. Human periapical cyst mesenchymal stem cells (hPCy-MSCs) represent a new category of dental stem cells, being collected from pathological tissue and exhibiting MSCs-like properties. As studies have described, these new identified cells possess the same characteristics as those described in MSCs, exhibiting plasticity, a high proliferation rate and the potential to differentiate into osteogenic, adipogenic and neural lineages. Reusing the biological tissue that is considered pathologic offers a new perspective for the development of further clinical applications. The identification and characterization of MSCs in the human periapical cysts allows for a better understanding of the molecular interactions, the potential healing capacity and the mechanisms of inducing the local osteogenic process, integrated in the microenvironment. Although their involvement in regenerative medicine research is recent, they exhibit important properties that refer them for the development of clinical applications in dentistry.