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The aim of this was to evaluate the histology of periapical lesions in teeth treated with periapical surgery. After root-end resection, the root tip was removed together with the periapical pathological tissue. Histologic sectioning was performed on calcified specimens embedded in methylmethacrylate (MMA) and on demineralized specimens embedded in LR White (Fluka, Buchs, Switzerland). The samples were evaluated with light and transmission electron microscopy (TEM). The histologic findings were classified into periapical abscesses, granulomas, or cystic lesions (true or pocket cysts). The final material comprised 70% granulomas, 23% cysts and 5% abscesses, 1% scar tissues, and 1% keratocysts. Six of 125 samples could not be used. The cystic lesions could not be subdivided into pocket or true cysts. All cysts had an epithelium-lined cavity, two of them with cilia-lined epithelium. These results show the high incidence of periapical granulomas among periapical lesions obtained during apical surgery. Periapical abscesses were a rare occasion. The histologic findings from samples obtained during apical surgery may differ from findings obtained by teeth extractions. A determination between pocket and true apical cysts is hardly possible when collecting samples by apical surgery.

Background: The clinical outcome of treatment of odontogenic cysts differs depending on separate entities. Particular clinical relevance must be attached to the distinction between odontogenic keratocysts, which have an evident tendency to recur, and other odontogenic cysts. The aim of this study was to evaluate cytokeratin (CK) expression patterns as an additional tool for characterization of different cysts as the histomorphologic appearance often is not decisive., Methods: Thirty cases of dentigerous and radicular cysts respectively as well as 15 cases of odontogenic keratocysts were considered. Expression of CK 5/6, 7, 10, 13, 17, 19 and 20 was determined in addition to Ki-67 immunohistochemically., Results: Expression of CK 17 was discernible in 93.3% of the odontogenic keratocysts, but only in 35.0% of dentigerous and radicular cysts under study (P < 0.001). CK 19 could be detected in 48.3% of dentigerous and radicular cysts, whereas odontogenic keratocysts were completely negative (P < 0.002)., Conclusion: Immunohistochemical detection of CK 17 and 19 seems to be a valuable additional parameter distinguishing between odontogenic keratocysts and other odontogenic--especially dentigerous--cysts which clinically are likely the most significant differential diagnoses in this context. J Oral Pathol Med (2005) 34: 558-64.

Background: A total of 325 cases of inflammatory paradental cysts (IPCs) and 17 own cases were reviewed. Although known since 1930, the IPC is still unrecognized by many clinicians. The IPCs show a relative frequency of 0.9-4.7%. The majority of cysts occur distally or distobuccally to vital, permanent mandibular molars with a history of pericoronitis (IPC/3rd mandibular molar alone accounts for 64.9%). Radiologically, the cyst appears as a well-defined, semilunar unilocular radiolucency., Materials and Methods: Cases of inflammatory paradental cysts and related lesions were retrieved from a worldwide literature survey. In addition, 17 new cases from the files of the authors have been added., Results: The mean ages for patients with IPC/1st, 2nd and 3rd mandibular molars are 8.7, 17.4 and 27.6 years, respectively. The male:female ratio was 1 : 0.9 for IPC/1st and 2nd mandibular molars, and 1 : 0.4 for 3rd mandibular molar., Conclusion: Reduced enamel epithelium, cell rests of Malassez and remnants of the dental lamina stimulated by inflammation are thought to play a role in the pathogenesis of IPC. Histological features are indistinguishable from those of the inflammatory, periapical (radicular) cyst.

Purpose: The purpose of this study was to analyze the effects of lesion site and epithelial keratinization on the morphologic characteristics of odontogenic cysts and clarify determinate factors for cyst morphology., Material and Methods: Computed tomographic images of 92 odontogenic cysts were analyzed: 31 primordial, 31 dentigerous and 30 radicular. Thirty-four cysts were located in the maxilla (6 primordial, 10 dentigerous, and 18 radicular) and 58 in the mandible (25 primordial, 21 dentigerous, and 12 radicular). Histologically, 31 cysts showed epithelial keratinization (18 primordial and 13 dentigerous). No keratinization was seen in radicular cysts. The morphologic features of cysts were assessed by measuring long length parallel to dental arch and short length vertical to it and calculating the long/short ratio. In addition, the computed tomography pattern of the cyst was classified into unilocular, lobulated, and multilocular patterns. Appearance of the sclerotic rim and surrounding cortex were classified into three and four patterns respectively to evaluate the developmental features of the cyst., Results: As a whole, the long length of the primordial cysts was statistically larger than the other two cyst groups and resulted in a larger long/short ratio. Statistical differences of CT pattern were also seen among cyst groups. There was no preference in any cyst group for the appearance of the sclerotic rim and cortex. There were statistical differences between maxilla and mandible in short axis and long/short ratio. The maxillary cysts generally showed round shapes irrespective of their histologic characteristics. A multilocular pattern was more frequent in the keratinized group of mandibular primordial cysts. In dentigerous cysts, a multilocular pattern was seen only in the keratinized group and the long/short ratio was statistically larger; cyst shape was elliptical along the long axis., Conclusion: Our results demonstrated morphologic differences of odontogenic cysts caused by lesion site and keratinization. The dentigerous cyst with predominant keratinization should be included in the primordial cyst (odontogenic keratocyst) group.

Objectives: To determine (1) the frequency of the incidence of abscess, granuloma, and radicular cyst among human periapical lesions obtained with extracted teeth; and (2) whether periapical cysts occur in two categories when histologically analyzed in relation to the root canals., Study Design: A total of 256 lesions were analyzed. The specimens were decalcified and embedded in plastic. Serial sections or step-serial sections were prepared, and the sections were evaluated on the basis of predefined histopathologic criteria., Results: The 256 specimens consisted of 35% periapical abscess, 50% granuloma, and 15% cysts. The latter occurred in two categories, the apical true cysts and the apical pocket cysts., Conclusions: These results show (1) the low incidence of radicular cysts among periapical lesions as against the widely held view that almost half of all periapical lesions are cysts; and (2) the occurrence of two classes of radicular cysts. We are of opinion that the pocket cysts may heal after root canal therapy but the true cysts are less likely to be resolved by conventional root canal treatment.