The aim of the study was to determine the distribution of histologically diagnosed nonodontogenic cysts (nOCs) over a 40-year period in a Brazilian population. Biopsy records from patients with nOC from the files of the Oral Pathology Service during the period of 1970-2009 were evaluated. Among 10,311 oral biopsies, 58 met the criteria of nOCs. The most frequent nOCs were nasopalatine duct cysts (32.8%), followed by epidermoid cysts (20.7%) and oral lymphoepithelial cysts (17.2%). Nasopalatine duct cysts showed predominance among females (68.4%). Epidermoid cysts were most commonly found in the floor of the mouth (36.4%), tongue (27.3%), and buccal mucosa (27.3%). Oral lymphoepithelial cysts exhibited female prevalence (80.0%) and were commonly located in the tongue (44.4%). The frequency of nOCs found in the population studied here is slightly different from those reported in other case series. Nasopalatine duct cysts, epidermoid cysts, and oral lymphoepithelial cysts were the most common nOCs found, accounting for 70.7% of all nOCs.

Low-level laser therapy (LLLT) has been shown to be effective in promoting cell proliferation. There is speculation that the biostimulatory effect of LLLT causes undesirable enhancement of tumor growth in neoplastic diseases since malignant cells are more susceptible to proliferative stimuli. This study evaluated the effects of LLLT on proliferation, invasion, and expression of cyclin D1, E-cadherin, β-catenin, and MMP-9 in a tongue squamous carcinoma cell line (SCC25). Cells were irradiated with a diode laser (660 nm) using two energy densities (0.5 and 1.0 J/cm(2)). The proliferative potential was assessed by cell growth curves and cell cycle analysis, whereas the invasion of cells was evaluated using a Matrigel cell invasion assay. Expression of cyclin D1, E-cadherin, β-catenin, and MMP-9 was analyzed by immunofluorescence and flow cytometry and associated with the biological activities studied. LLLT induced significantly the proliferation of SCC25 cells at 1.0 J/cm(2), which was accomplished by an increase in the expression of cyclin D1 and nuclear β-catenin. At 1.0 J/cm(2), LLLT significantly reduced E-cadherin and induced MMP-9 expression, promoting SCC25 invasion. The results of this study demonstrated that LLLT exerts a stimulatory effect on proliferation and invasion of SCC25 cells, which was associated with alterations on expression of proteins studied.

Low-level laser irradiation (LLLI) stimulates the proliferation of a variety of cell types. However, very little is known about the effect of laser therapy on dental stem cells. The aim of the present study was to evaluate the effect of LLLI (660 nm, 30 mW) on the proliferation rate of human periodontal ligament stem cells (hPDLSC), obtained from two healthy permanent third molars extracted due to surgical indication. Culture cells were either irradiated or not (control) with an InGaAIP diode laser at 0 and 48 h, using two different energy densities (0.5 J/cm², 16 s and 1.0 J/cm², 33 s). Cell proliferation was evaluated by the Trypan blue exclusion method and by measuring mitochondrial activity using the MTT-based cytotoxicity assay at intervals of 0, 24, 48, and 72 h after the first laser application. An energy density of 1.0 J/cm² improved the cell proliferation in comparison to the other groups (control and laser 0.5 J/cm²) at 48 and 72 h. The group irradiated with 1.0 J/cm² presented significantly higher MTT activity at 48 and 72 h when compared to the energy density of 0.5 J/cm². It can be concluded that LLLI using infrared light and an energy density of 1.0 J/cm² has a positive stimulatory effect on the proliferation of hPDLSC.

Pleomorphic adenoma (PA) is the most frequent benign epithelial lesion of salivary gland origin, showing great histopathological diversity. The aim of this study was to perform a retrospective analysis, with emphasis on histopathologic features of PA of salivary glands. Clinical and histopathologic characteristics of 130 cases of minor and major salivary glands PAs from three Brazilian reference centers were studied. Higher frequency of PAs was observed in female (55.4 %) subjects, with mean age of 49.7 years. The most common affected site was palate (64.5 %) for the PAs of minor salivary glands and parotid for cases affecting major glands (86.2 %). Microscopically, most cases were classified as classic PAs (50 %). Incomplete capsule was observed in 36.2 % of the cases, while 47.2 % showed capsular infiltration. Rounded (66.9 %), angular (49.2 %), oval (46.2 %) and plasmacytoid (39.2 %) cells were widely observed, as well as fibrous (73.8 %) and myxoid (69.2 %) stroma, squamous metaplasia (25.4 %) and cystic degeneration (43.1 %). Crystalloids (3.1 %), increased mitotic activity (5.4 %) and vascular invasion (2.3 %) were rarely observed. PAs arising in minor salivary glands were associated with incomplete capsules, spindle, oval, angular, plasmacytoid and pleomorphic cells, fibrous and hyaline stroma, cystic degeneration, squamous metaplasia and pleomorphism (p < 0.05). No association between capsular features and histological subtype was noted (p ≥ 0.05). These results confirm the findings of previous studies regarding major clinicopathological features of pleomorphic adenomas; and highlighted some important morphologic characteristics like the capsule, vascular invasion, pleomorphism and increased mitotic activity, which can reflect the biological behavior of these tumors.

Objective. The aim of this study was to evaluate the immunohistochemical expression of collagen IV, matrix metalloproteinase (MMP) 9 and tissue inhibitor of MMP (TIMP) 2 in dentigerous cysts (DCs), radicular cysts (RCs), keratocystic odontogenic tumors (KOTs), and ameloblastomas. Study design. Twenty cases of DCs, 20 RCs, 20 KOTs, and 20 ameloblastomas were selected and analyzed by immunohistochemistry. Results. Most DCs and RCs showed continuous and Ͼ50% staining for collagen IV in the basement membrane of the epithelium, whereas predominantly discontinuous thin and Յ50% staining was observed in KOTs and ameloblastomas, with a significant difference in staining percentage (P Ͻ .001). MMP-9 was diffusely distributed and localized in both epithelial and mesenchymal cells of all of the lesions analyzed. The staining percentage was higher in the epithelium (P ϭ .058) and mesenchyme (P ϭ .005) of KOTs and ameloblastomas. Moreover, the distribution pattern, location, and percentage of expression of TIMP-2 were similar in the lesions studied, except for ameloblastoma, with a significant difference in staining percentage (P Ͻ .001).Conclusion. These results demonstrate that the interaction between collagen IV, MMP-9, and TIMP-2 is an important factor for the establishment of differences in the biologic behavior of the odontogenic cysts and tumors studied. Factors related to the epithelial and mesenchymal components participate in the regulation of the growth of odontogenic cystic lesions and tumors. 1 The altered expression of specific proteins of the extracellular matrix (ECM), associated with the exuberant presence of matrix metalloproteinases (MMPs) and the absence of expression of metalloproteinase inhibitors (TIMPs), may influence the behavior of these lesions. In the case of tumors, this situation contributes to the growth and higher aggressiveness of the tumor. 2 The odontogenic keratocyst, recently reclassified as keratocystic odontogenic tumor (KOT), 3 is known for its aggressive nature and high rate of recurrence, especially compared with other odontogenic cysts. 4 Ameloblastoma is a locally aggressive benign epithelial odontogenic tumor with a marked invasion potential that results in multiple recurrences after enucleation and curettage. 5 In contrast, dentigerous (DC) and radicular (RC) cysts show an indolent behavior and rarely recur after surgical removal. KOT presents a cystic structure similar to that of DC and RC, but its invasive and destructive growth is similar to that of ameloblastoma. 6 KOT, ameloblastoma, DC, and RC show distinct evolutions and biologic behaviors. In view of this fact, a growing number of studies have tried to identify