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Introduction: The purpose of this study was to identify nonendodontic periapical lesions (NPLs) mimicking endodontic pathosis, which are most frequently encountered by clinicians., Methods: A retrospective study was conducted on biopsies obtained from 2015-2020 at Texas A&M College of Dentistry's oral pathology laboratory. The online database was screened for cases submitted as suspected endodontic pathology using specific key words. Histologic diagnoses were collected to determine the prevalence of NPLs that were originally thought to be of endodontic origin. The frequency and percentage of endodontic pathology and NPLs were documented., Results: Among 6704 biopsies clinically diagnosed as endodontic lesions, 190 (2.8%) were histopathologically diagnosed as NPLs. The most frequent NPLs were odontogenic keratocytes' (n = 70, 36.8%), cemento-osseous dysplasia (n = 27, 14.2%), and dentigerous cysts (n = 22, 11.6%). Of all NPLs, 3.7% were malignant neoplasms, with the most common diagnosis being squamous cell carcinoma. Of 6514 endodontic histologic diagnoses, the prevalence of periapical granulomas and cysts was 60.2% (n = 3924) and 39.1% (n = 2549), respectively., Conclusions: Although most endodontic submissions are likely to be histologically diagnosed as periapical granulomas or cysts, the clinician should be aware that a small portion of these lesions may be nonendodontic in origin and possibly neoplastic in nature. Histopathologic evaluation of biopsied specimens is critical to achieve a proper diagnosis to ensure the appropriate management of patients., (Copyright © 2022 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

We describe complete healing of an extensive cystic lesion by using a conservative approach: root canal treatment with concurrent surgical drainage. A silicone Foley catheter drain was modified into a surgical drainage stent, which was then used for 4 weeks. Disinfection of the root canal was achieved by the use of hand files and irrigation with 5.25% NaOCl for a minimum of 30 minutes. The irrigant changes were performed at 5-minute intervals, and no intracanal dressing was used. At subsequent follow-up examinations, cone-beam computed tomography and periapical radiographs confirmed that complete healing had occurred around the periapical and lateral areas of affected teeth. This case report indicates the potential for healing of large cystic lesions by nonsurgical root canal treatment., (Copyright © 2018 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: The aim of this study was to evaluate the possible associations among the histopathological diagnosis, the inflammatory infiltrate profile, the presence of pain, and the immunoexpression of matrix metalloproteinases MMP-2 and MMP-9 in periapical lesions from primary endodontic infection., Methods: Fifty-one primary periapical lesions obtained from extracted teeth were selected for this study. Patients were previously evaluated for the presence of pain and sinus tract related to the tooth to be extracted. Tissues were processed for microscopic examination and MMP-2 and MMP-9 immunoexpression. Microscopically, samples were classified as periapical granulomas or periapical cysts and the inflammatory infiltrate as chronic or mixed. The percentage of immunopositive cells for MMP-2 and MMP-9 of each case was performed based on 10 consecutive microscopic fields. The Student t or chi-square tests were used in the statistical analysis., Results: Of the total, 28 cases were classified as periapical granulomas (54.90%) and 23 cases as periapical cysts (45.10%). Seventeen patients (33.33%) reported pain associated with the extracted tooth, with 12 cases of periapical granulomas (70.58%) and 5 cases of periapical cysts (29.42%). All cases showed immunopositivity for MMP-2 and MMP-9 in a high percentage of cells, mainly in the cytoplasm of the leukocytes. MMP-2 was expressed more in periapical granulomas than periapical cysts (P < .05) and in symptomatic cases (P < .05)., Conclusions: According to the results, we may conclude that MMP-2 and MMP-9 are highly expressed in periapical lesions from a primary endodontic infection. Moreover, we may suggest MMP-2 is expressed more in periapical granuloma and in cases associated with pain., (Copyright © 2016 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: Inflammatory cysts, granulomas, abscesses, and fibrous scars represent most periapical radiolucencies. However, other less common lesions, such as orthokeratinized odontogenic cysts (OOCs), can be found at this region, and they deserve to be discussed because the prognosis for an OOC is different from that expected for the ordinary inflammatory periapical diseases., Methods: An interesting case of OOC associated with a nonvital tooth in a 40-year-old woman is described. After a previous clinical diagnosis of a radicular cyst, the tooth was extracted, and the lesion was enucleated and submitted to microscopy examination., Results: Because of the detection of an orthokeratinized epithelium lining, a diagnosis of OOC was concluded. After 2 years of periodic follow-up, no signs of recurrence were detected., Conclusions: The presence of keratin in radicular lesions must be carefully evaluated to eliminate the diagnosis of lesions with more aggressive behavior, such as an OOC or even a keratocystic odontogenic tumor. Hence, histopathologic examination is mandatory to confirm the type of lesion and to differentiate other pathologic conditions, therefore establishing patients' prognoses precisely., (Copyright © 2014 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This article describes a case in which signs and symptoms persisted in spite of the endodontic treatment following high standards to characterize a short-term failure., Methods: After several appointments of root canal treatment in an attempt to resolve persistent symptoms, including 106 days of calcium hydroxide intracanal medication, periradicular surgery was performed, and the root apex and the lesion were subjected to histologic and histobacteriologic analyses., Results: The lesion was diagnosed as a cyst, and the main root canal was free of bacteria and debris., Conclusions: The cause of the short-term failure was an exuberant bacterial biofilm colonizing a lateral canal in the apical root segment. This case report highlights one of the major problems of modern endodontic therapy; bacteria located in areas distant from the main root canal can remain unaffected by treatment procedures and maintain disease. The challenge for researchers and clinicians that arises from this problem is to develop strategies, instruments, or substances that can reach those areas and achieve sufficient reduction in the infectious bioburden to permit predictable periradicular healing., (Copyright © 2013 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: An accurate differential diagnosis of apical periodontitis (AP) and nasopalatine duct cyst (NPDC) should be established to define the best treatment for endodontically treated maxillary anterior teeth with apical periodontitis. Three-dimensional cone beam computed tomography (CBCT) images help to plan treatment and to define an initial diagnostic hypothesis. However, endodontic treatment or retreatment may be unnecessarily prescribed when radiographs show a superimposition of the incisor foramen over the apex of maxillary central incisors, mimicking AP. Diseases of nonendodontic origin that affect the tooth apex, such as NPDC, should be included in the differential diagnosis., Methods and Results: Four clinical cases of patients with large periapical radiolucencies and similar radiographic features are described. AP is usually a consequence of endodontic infection; in cases of NPDC, however, spontaneous epithelial proliferation, in addition to bacterial infection and trauma, may also contribute to cyst formation. The frequency and recurrence rates of NPDC are low, and its behavior is less aggressive. Surgical enucleation of the periapical lesion is recommended after nonsurgical treatment does not heal AP., Conclusions: The use of new diagnostic tools, such as CBCT imaging, may provide detailed high-resolution images of oral structures, which help to make an initial diagnostic hypothesis and to plan surgery. Histopathology is mandatory for the differential diagnosis., (Copyright © 2011 American Association of Endodontists. Published by Elsevier Inc. All rights reserved.)

Introduction: This study investigated the differentiation of radicular cysts from granulomas. Cone beam computed tomography (CBCT) imaging was compared with the existing standard, biopsy and histopathology., Methods: Forty-five patients scheduled for an apicoectomy received a CBCT scan of the involved arch. Two oral and maxillofacial radiologists, working independently and using the same criteria, categorized the CBCT images as one of the following: cyst, likely cyst, likely granuloma, granuloma, or other. After apicoectomies, two oral pathologists, working independently and using the same criteria, diagnosed the surgical specimens as one of the following: radicular cyst, granuloma, or other. We examined the following: (1) interrater agreement between pathologists as to the biopsy diagnosis, (2) interrater agreement between radiologists as to the CBCT diagnosis, and (3) accuracy of radiologists' diagnostic assessments using histopathology as the standard., Results: Findings showed strong interrater reliability between pathologists (kappa=0.79, z=5.46, p<0.0001) and weak interrater reliability between radiologists (kappa=0.14, p=not significant). Accuracy (true-positives plus true-negatives) for the two radiologists was 51% and 63%., Conclusion: Under the conditions of this study, based on the inconsistency of the radiologists' reports as evidenced by statistical analyses, it was concluded that CBCT imaging is not a reliable diagnostic method for differentiating radicular cysts from granulomas. Surgical biopsy and histopathological evaluation remain the standard procedure for differentiating radicular cysts from granulomas., (Copyright (c) 2010. Published by Elsevier Inc.)

Introduction: This report of 2 cases describes the diagnostic procedures used to identify 2 Stafne's bone cavities (SBC) found in unusually anterior locations in the mandible, both mimicking periapical lesions of endodontic origin., Methods: In the first patient, a 47-year-old man, an SBC was diagnosed in the area of teeth #27, 28, and 29. In the second patient, a 62-year-old man, the SBC was a fortuitous finding, because this patient was referred for dental implant therapy., Results: In both cases, the final diagnosis was achieved by using limited cone beam computed tomography (CBCT) and magnetic resonance imaging (MRI). In both patients, the lingual bone cavity was found to be occupied by accessory salivary gland tissue., Conclusions: The combination of CBCT and MRI as noninvasive diagnostic techniques seems ideal to avoid surgical explorations, incisional biopsies, or enucleations of the lesion for diagnostic purposes.

Introduction: The inability to distinguish periapical cysts from granulomas before performing root canal treatment leads to uncertainty in treatment outcomes because cysts have lower healing rates. Searching for differential expression of molecules within cysts or granulomas could provide information with regard to the identity of the lesion or suggest mechanistic differences that may form the basis for future therapeutic intervention. Thus, we investigated whether granulomas and cysts exhibit differential expression of extracellular matrix (ECM) molecules., Methods: Human periapical granulomas, periapical cysts, and healthy periodontal ligament tissues were used to investigate the differential expression of ECM molecules by microarray analysis. Because matrix metalloproteinases (MMP) showed the highest differential expression in the microarray analysis, MMPs were further examined by in situ zymography and immunohistochemistry. Data were analyzed by using one-way analysis of variance followed by the Tukey test., Results: We observed that cysts and granulomas differentially expressed several ECM molecules, especially those from the MMP family. Compared with cysts, granulomas exhibited higher MMP enzymatic activity in areas stained for MMP-9. These areas were composed of polymorphonuclear cells (PMNs) in contrast to cysts. Similarly, MMP-13 was expressed by a greater number of cells in granulomas compared with cysts., Conclusion: Our findings indicate that high enzymatic MMP activity in PMNs together with MMP-9 and MMP-13 stained cells could be a molecular signature of granulomas unlike periapical cysts.

This article describes a case of persistent apical periodontitis that required several nonsurgical and surgical approaches for resolution. A 28-year-old woman presented with a large symptomatic apical periodontitis lesion associated with the maxillary left lateral incisor that persisted in spite of previous nonsurgical and surgical endodontic treatment. Root canal retreatment was accomplished, but the lesion only showed a slight decrease in size after 18 months. Forty-six months after retreatment, the patient returned because of reemergence of symptoms. Radiographically, the lesion remained relatively unaltered. Periradicular resurgery was performed, and a biopsy specimen consisting of the lesion and the apical part of the root was collected for analysis. Radiographic and clinical reevaluation after 4 years revealed complete healing. Histopathologic and histobacteriologic observations demonstrated that the lesion was a cyst, and that the probable reason for failure was the occurrence of bacteria within dentinal tubules and in a lateral canal slightly coronal to the amalgam root-end filling. This case report clearly illustrates the difficulties imposed by anatomic complexities in attaining a disinfection level that is compatible with periradicular tissue healing.

A distinctive form of paradental cyst can occur on the buccal and apical aspects of erupted mandibular molars. This cyst has peculiar clinical and radiographic features, although the microscopic findings are the same as those of odontogenic inflammatory cysts. Diagnostic and therapeutic problems can occur when this lesion is misinterpreted as a radicular cyst. The purpose of this paper is to present an additional case of a paradental cyst in the buccal and mesial aspects of a mandibular second molar involving the apical area of a mandibular first molar. The difficulty of diagnosis, treatment, and controversies regarding terminology are also discussed.

The endoscope utilized by otolaryngologists for the past 10 yr has a place in the armamentarium of the endodontist as well. It provides improved visualization of root apicies, especially those not in the line of direct vision. It can illuminate and identify roots in the sinus if such treatment becomes necessary. By allowing a magnified view of the root-end preparation before and after placement of the filling material, any fractures or extraneous material can be identified. This instrument is quite small and readily transportable from one operatory to another. The cost is a fraction of the price of the surgical microscope.

A case report of a maxillary first molar is presented in which a drainage tube from a decompression procedure was removed 2 days following placement. The oral surgeon who removed the tube scheduled the patient for surgical enucleation of the large periapical lesion. The surgical appointment was subsequently cancelled and routine endodontic follow-up showed continued osseous repair at 3, 6, and 12 months. The decompression of a large periapical lesion is a conservative alternative to surgical enucleation.