Expression of transforming growth factor-beta 1 (TGF-beta 1) in odontogenic cysts

AIM: To evaluate the positivity to transforming growth factor-beta 1 (TGF-beta 1) in different types of odontogenic cysts. METHODOLOGY: A total of 30 radicular cysts (RCs), 27 follicular cysts (FCs) and 28 odontogenic keratocysts (OKCs) were evaluated for immunohistochemical analysis of TGF-beta 1. TGF-beta 1 was evaluated in blood vessels, stromal cells (fibroblasts) and pluristratified squamous epithelium. TGF-beta 1 expression was determined by evaluating the number of positive elements. TGF-beta 1 expression was determined by evaluating 1000 cells in the pluristratified squamous epithelium (500 in the basal and parabasal layers, and 500 in the superficial layer) and 500 cells (the fibroblasts in the stroma) for each specimen, and counting the number of positive cells. The number of positive vessels was evaluated in 10 high power fields (HPF). The Chi-square test was used to evaluate differences between the two groups (RC + FC and OKC). A P-value <0.05 was considered to indicate statistical significance. RESULTS: A higher and statistically significant positivity was found in the basal-suprabasal epithelial layers (P=0.0011), superficial epithelium (P=0.053) and stromal cells (P=0.0002) of orthokeratotic and parakeratotic OKC as compared with RC and FC. CONCLUSIONS: These differences suggest that control of the cell cycle may be abnormal in orthokeratotic OKCs. These OKCs may have an intrinsic growth potential not present in other cyst types.     

CD1a-positive cells in odontogenic cysts

Langerhans cells (LC) are bone marrow-derived cells that have a CD1a-positive immunophenotype and are an important portion of the cell-mediated immune response. The aim of this study was an immunohistochemical evaluation of CD1a positive cells in different types of oral cysts. Fifty-five cysts were studied: 18 odontogenic keratocysts (OKC), of which five were orthokeratotic and 13 parakeratotic; 19 radicular cysts; and 18 dentigerous cysts. Positive LC was 80% for orthokeratotic OKC, 33% for parakeratotic OKC, approximately 35% for radicular cysts, and approximately 20% for dentigerous cysts. The results show that OKC with well-differentiated epithelial linings presented a greater number of LC than the other cysts. However, when the cyst wall was inflamed there were no differences in LC expression in the different types of cysts. The data confirm that LC distribution seems to be associated with the degree of differentiation of the epithelia.     

p53 expression in odontogenic keratocyst epithelium

The expression of p53 protein was studied in odontogenic keratocysts (OKC, 11 solitary, 5 recurrent and 6 NBCCS cysts), radicular (RC, n=5) and dentigerous (DC, n=5) cysts, using a panel of antibodies to p53 (clone BP53-12, clone 1801 and polyclonal CM1) and a sensitive biotin-streptavidin method on paraffin embedded sections. Of the three antibodies tested, clone BP53-12 gave the most intense and consistent nuclear staining pattern. Clone 1801 and polyclonal CM1 stained only 38% and 71% OKC linings, respectively, but not RC and DC linings. However, BP53-12⁺ cells were detected in the epithelial linings of all cyst types. Quantification of BP53-12⁺ cells was performed by manual counting and by relating cell number to unit length of basement membrane as determined by TV image analysis. BP53-12⁺ cell counts in solitary OKC linings (25.5 ± 11.0 cells/mmBM) were significantly greater than those in DC (9.3 ± 4.9 cells/mmBM, P<0.01) and RC (6.7 ±2.6 cells/mmmBM. P<0.01) linings. The epithelial distribution of positive cells in OKC was predominantly suprabasal, which also varied from that of DC and RC linings (P<0.005). There were no detectable differences in BP53-12 reactivity between the different subtypes of OKC (i.e., solitary, recurrent and NBCCS-associated OKC: P>0.1). When data for the NBCCS-related OKC group were excluded, there was a significant correlation (r=0.55. P<0.01) between p53 and Ki67 labelling. To detect the presence of p53 gene mutations, genomic DNA, extracted from paraffin sections of OKC (4 solitary, 2 recurrent and 4 NBCCS cysts). RC (n=3) and normal oral mucosa (n=1), was subjected to a combination of polymerase chain reaction and single-stranded conformation polymorphism (PCR-SSCP) analysis for exons 5-10 of the p53 gene. Exon 4 was not analysed because of compromised DNA quality. No abnormality in banding patterns was found and all samples save results similar to DNA from known, sequenced, normal p53 gene controls. Absence of p53 mutations within exons 5–9 was confirmed by the direct sequencing of 2 fresh frozen OKC samples (1 solitary and 1 NBCCS cyst). These results suggest that over expression of p53 protein in OKC epithelium, detected by immunocytochemistry, is not reflected by alteration of the p53 gene and presumably reflects overproduction and/or stabilisation of normal p53 protein.     

Immunohistochemical expression of vascular endothelial growth factor (VEGF) in different types of odontogenic cysts

The objective of the present study was to evaluate vascular endothelial growth factor (VEGF) expression in different types of odontogenic cysts. A total of 25 parakeratotic odontogenic keratocysts (POKCs), 16 orthokeratotic odontogenic keratocysts (OOKCs), and 28 follicular cysts (FCs) were evaluated semiquantitatively for immunohistochemical analysis of VEGF in epithelial cells, endothelial cells of blood vessels, inflammatory cells and focally stromal cells. A significant different expression of VEGF in all cell components was found in keratocysts compared to FCs. The POKCs (80%) and OOKCs (68%) showed more than 50% VEGF positive epithelial cells, whereas the majority of FCs (71%) were either negative in the epithelium or showed less than 10% positive cells. Similarly, the POKCs (88%) and OOKCs (68%) showed more than 50% positive endothelial cells, whereas the FCs (75%) were either negative or showed less than 10% VEGF positive endothelial cells. The highest percentage of cases with score 2 positivity in the stromal cells was observed in POKCs (68%); OOKCs showed a score 2 positivity in 44%, score 1 in 31% and score 0 in 25%, whereas 68% of FCs showed a score 0, 25% a score 1 and only 7% of cases showed a score 2. No statistically significant differences were observed between POKCs and OOKCs in VEGF expression in the epithelial and endothelial cells, whereas the positivity score in stromal cells was significantly higher in POKCs compared to OOKCs. The present results can support the hypothesis that angiogenesis is an active mechanism in the invasive growth of the OKC.     

Scanning electron microscopy of odontogenic cyst epithelium.

The epithelial lining of 8 odontogenic keratocysts (OKC), 9 radicular (RC) and 3 dentigerous cysts (DC) were examined in SEM in order to study the ultrastructural surface topography of the lumenal surface cells. The orthokeratinized OKC showed a reticular network of intercommunicating microridges surrounding micropits giving a honeycombed appearance to the entire surface. The deep surface of these cells was covered by a complementary array of short stubby microvilli. This pattern was identical to that described for oral epithelium in areas of masticatory mucosa. The parakeratinized OKC showed a complex pattern of microplications (MP) on both upper and deep cell surfaces. The non-keratinized linings of RC and DC revealed a similar MP pattern but of a less complex nature. The MP pattern of cells from para- and non-keratinized cysts was identical to that described for oral epithelial cells from lining mucosa. The surface ultrastructure of ciliated, mucus and brush cells occurring in RC was found to be indistinguishable from that described in the mammalian respiratory tract. The MP pattern forms part of the cellular interdigitation mechanisms in stratified squamous epithelium. Differences in the ultrastructural configuration are related to the type of epithelium in terms of keratinization rather than to protective functions.     

Survivin、Ki67在牙源性囊肿上皮组织中的表达及意义

目的：探讨根端囊肿、含牙囊肿及角化囊肿衬里上皮中Survivin、Ki67的表达及意义。方法：采用免疫组化法检测12例根端囊肿、20例含牙囊肿、22例角化囊肿中Survivin、Ki67表达水平,并加以分析。结果：Survivin在根瑞囊肿中无表达,在含牙囊肿和角化囊肿中表达的阳性率分别为10％、63．6％,角化囊肿OD值显著高于根端囊肿和含牙囊肿（P〈0．05）;Ki67在3种组织中均有表达,角化囊肿中Ki67-ＬＩ显著高于根端囊肿和含牙囊肿（Ｐ〈0．05）;角化囊肿中Survivin阳性表达的Ki67-LI显著高于表达阴性者（Ｐ〈0．05）,且Survivin表达与Ki67表达呈正相关（r=0．452,P〈0．05）。结论：survivin、Ki67在牙源性囊肿中的表达差异显示了它们具有不同的增殖和分化过程。     

Epithelial cell proliferation in odontogenic keratocysts: a comparative immunocytochemical study of Ki67 in simple, recurrent and basal cell naevus syndrome (BCNS)-associated lesions

The aim of the present study was to investigate epithelial cell proliferation in the linings of odontogenic cysts, including three different subtypes of odontogenic keratocyst (OKC), namely simple (non-recurrent), recurrent and basal cell naevus syndrome (BCNS)-associated lesions. Ki67 immunoreactivity in OKC (simple, n = 10; recurrent, n = 8; syndrome, n = 9), dentigerous cysts (DC, n = 5), radicular cysts (RC, n = 5) and normal oral mucosa (n = 7) was studied using a biotin-streptavidin-peroxidase method on paraffin sections after microwave treatment. Ki67⁺ epithelial cells were counted manually and related to the length of basement membrane (BM) as determined by TV image analysis. Data were analysed by the Mann-Whitney U test. The number of Ki67+ cells in simple OKC linings (53.1 ± 17.8 cells/ mmBM) was similar to that in oral epithelium (42.5 ± 12.7 cells/mmBM; P>0.2). However, both contained significantly more Ki67+ cells than DC (3.9 ± 1.3 cells/ mmBM) and RC linings (6.7 ±4.8 cells/mmBM; P<0.006). The epithelial distribution of Ki67⁺ cells differed between groups, with the percentage of positive cells in basal layers in OKC linings (7.0 ± 2.1%) being significantly lower than that of oral epithelia (35.9 ± 5.6%), DC (78.4 ± 8.4%) and RC (80.6 ± 7.7%) linings respectively (P<0.003). Comparison of Ki67 expression within the OKC group revealed no significant difference between simple and recurrent lesions (44.0 ± 13.8 cells/ mmBM; P>0.3). However, OKC associated with BCNS contained significantly higher numbers of Ki67+ cells (91.8±35.6 cells/mmBM; P<0.01). There was no difference in epithelial distribution of positive cells between the OKC groups. The results are consistent with OKC having a greater proliferative capacity than DC and RC and that its recurrence is not associated with a subgroup of lesions exhibiting increased proliferation. The increased proliferation in OKC associated with BCNS presumably reflects the underlying genetic defect(s) in this syndrome.     

Expression of keratinocyte growth factor and its receptor in odontogenic keratocysts

Background:  The mitotic activity of the epithelial cells of odontogenic keratocysts (OKCs) is greater than that of other odontogenic jaw cysts, and the mitotic activity of the epithelial cells decreases after marsupialization. Keratinocyte growth factor (KGF) interacts with its specific receptor (KGFR), and elicits the proliferation and/or differentiation of the various types of epithelial cells. The aim of this study was to investigate the expression of KGF/KGFR in OKCs before and after marsupialization.
Methods:  The expression of KGF was immunohistochemically detected in the specimens of 16 OKCs and 11 dentigerous cysts before and after marsupialization. The expression of KGF mRNA was measured in the fibroblasts isolated from OKCs by real-time PCR.
Results:  KGF was expressed in the epithelial cells and fibroblasts of 12 and seven of 16 OKC specimens, respectively. The intensity of the KGF expression in both the epithelial cells and the fibroblasts significantly decreased after marsupialization. KGFR was expressed throughout the epithelium in 15 of 16 OKC specimens, but the intensity of the KGFR expression did not change after marsupialization. The expression of KGF was detected in the epithelium of two of 11 dentigerous cyst specimens, but not in the fibroblasts before marsupialization. Real-time PCR revealed that recombinant human interleukin (IL)-1α increased the expression of KGF mRNA in the fibroblasts isolated from OKCs.
Conclusion:  KGF/KGFR signaling may play a crucial role in the epithelial cells of OKCs. Furthermore, the expression of KGF in the fibroblasts of OKCs is regulated by IL-1α.     

Laminin-5 gamma 2 chain is colocalized with gelatinase-A (MMP-2) and collagenase-3 (MMP-13) in odontogenic keratocysts

Background: Odontogenic keratocyst (KC) differs from other epithelial odontogenic cysts in regard to increased epithelial proliferation and a strong tendency to recur. Laminin‐5 (Ln‐5) is an epithelial anchoring filament component, which after modulation by certain matrix metalloproteinases (MMPs), like MMP‐2 and MMP‐13, induces epithelial cell migration. Methods: Using in situ hybridization and immunohistochemistry, we studied the Ln‐5 gamma‐2 chain expression related to the expression of MMP‐2, ‐8, and ‐13 in different odontogenic cysts, including radicular cysts (RC; n = 11), follicular cysts (FC; n = 11), and odontogenic keratocysts (KC; n = 16). Results: Ln‐5 mRNA was present in all cysts examined, while less than half of KCs and RCs (33 and 40%, respectively) demonstrated MMP‐2 mRNA. MMP‐13 mRNA was present in all KC samples. Ln‐5 protein was located as a continuous ribbon in BM zone of all KCs, and MMP‐2 and MMP‐13 immunoreactivities colocated significantly with Ln‐5 in that area. MMP‐8 was expressed by stromal macrophages and epithelial goblet cells, but never located in BM zone. Conclusions: Our results indicate that the colocalization of Ln‐5 with MMP‐2 or MMP‐13, but not with MMP‐8, in BM zone of KCs, may be related to special characteristics of KC.     

A radiologic analysis of dentigerous cysts and odontogenic keratocysts associated with a mandibular third molar

OBJECTIVE: The purpose of this study was to discriminate radiographically between dentigerous cysts (DCs) and odontogenic keratocysts (OKCs) associated with a mandibular third molar. STUDY DESIGN: The material consisted of panoramic radiographs of dentigerous cysts (44 patients, 45 cysts) and odontogenic keratocysts (15 patients, 16 cysts), all of which were related to a mandibular third molar. The radiographic images were analyzed with reference to the patients' ages and symptoms. RESULTS: The mean age of patients in the OKC group was less than that of patients in the DC group. The mean area of the cysts in the OKC group was larger than that of those in the DC group. The mean distance from the second to the third molar in the DC group was greater than that in the OKC group. Although there was a significant correlation between the area and distance in the DC and OKC groups, the patients' ages did not significantly correlate to the area and distance of either cyst. CONCLUSIONS: The OKCs had a tendency toward rapid growth in the patient's youth but short movement of a third molar compared with the DCs. The DCs and OKCs do not appear to develop gradually from the period when follicles or dental lamina were formed but arise at various periods randomly.     

A comparative study of epithelial cell proliferation between the odontogenic keratocyst, orthokeratinized odontogenic cyst, dentigerous cyst, and ameloblastoma

OBJECTIVES: The aim of the present study was to compare the proliferation index of the epithelial cells between odontogenic keratocysts (OKC), orthokeratinized odontogenic cysts (OOC), dentigerous cysts (DC), and ameloblastomas. MATERIALS AND METHODS: The proliferation index, employing a novel cell proliferation marker IPO-38, was studied by the immunohistochemical technique in 10 OKC, seven OOC, eight DC and 10 ameloblastomas. RESULTS: The ameloblastoma had no higher labeling index (LI) of IPO-38 than the OKC (P = 0.910) but had higher LI than the OOC (P = 0.001) and DC (P = 0.000); the OKC had higher LI than the OOC (P = 0.002) and DC (P = 0.000); and the OOC had higher LI than the DC (P = 0.011). IPO-38-positive cells in the OKC and OOC were located principally in the suprabasal cell layers while the ameloblastoma were found in the peripheral portion in particularly, the follicular and plexiform types. CONCLUSION: These findings support previous studies that the proliferation indices are useful in predicting the different biological behavior of the odontogenic lesions and the OKC should be regarded as a benign tumor rather than simply an odontogenic cyst.     

Profiling of radicular cyst and odontogenic keratocyst cytokine production suggests common growth mechanisms

The aim of this study was to compare the cytokine expression profiles of cyst fluids (CFs) and tissue culture supernatants (SUPs) from 7 radicular cysts (RCs) and 7 odontogenic keratocysts (OKCs) by using Human Cytokine Antibody Array to identify the specific cytokines involved in formation and expansion of RCs and OKCs, respectively. There were significant differences in relative expression levels of IL-1 beta, MCP1, MIP1 beta, FGF-9, GDNF, HGF, IGFBP-3, Ang, IP-10, MIF, OPG, and TGF-beta2 between RC-CF and OKC-CF (P < .05). On the other hand, the cytokine expression patterns of RC-SUP (HGF, IL-8, NAP-2, IL-6, TIMP-1 and 2, GRO, IP-10, and Ang) were similar to those of OKC-SUP. Only the relative expression level of GRO differed between RC-SUP and OKC-SUP (P < .05). The similarities of cytokine production by tissue cultures derived from RC and OKC indicate that the expansion mechanisms of RC and OKC might involve similar biologic mechanisms other than infection.     

p53 protein and Ki-67 reactivity in epithelial odontogenic lesions. An immunohistochemical study

Forty-five examples of epithelial odontogenic lesions (9 ameloblastomas (AB): 13 odontogenic keratocysts (OKC): 15 dentigerous cysts (DC): 6 radicular cysts (RC): and 2 odontogenic carcinomas (OC)) were immunohistochemically analyzed for the presence of p53 protein (p53P) and proliferative activity as indicated by positivity for Ki-67 antigen. p53P⁺ cells, detected as dense and/or faint nuclear staining, were found in 42 of the 45 odontogenic lesions examined. Dense p53P reactivity was most commonly detected in OKC, AB and OC, with other lesions generally exhibiting only weak nuclear reactivity. Numbers of Ki-67 positive cells as well as p53P⁺ cells were scored semiquantitatively. Although the presence/absence of densely stained p53P⁺ cells was broadly related to Ki-67⁺ cell numbers, there were no differences in p53P⁺ cell numbers between lesions exhibiting differences in proliferative activity. These results suggest that overexpression of p53P, rather than increased numbers of p53P⁺ cells, is related to proliferation in odontogenic epithelial lesions.     

Survivin expression in odontogenic keratocysts and correlation with cytomegalovirus infection

Oral Diseases (2010) 16 , 156–159 Objectives: The aim of this study was to investigate the expression of survivin, an inhibitor of apoptosis, in odontogenic keratocysts and to compare it to the findings in non‐neoplastic jaw cysts – periapical cysts, as well as to establish a possible relationship between survivin expression and human cytomegalovirus presence within these cysts. Materials and methods: Samples of 10 odontogenic keratocysts (five positive and five negative for the presence of cytomegalovirus, as determined by polymerase chain reaction) and 10 periapical cysts (five positive and five negative for the cytomegalovirus presence) were analysed. The expression of survivin was assessed by immunohistochemical methods, using monoclonal antibody that selectively recognizes the cytoplasmic form of survivin. Results: All 10 odontogenic keratocysts showed immunostaining for survivin, while all 10 periapical cysts were negative for its presence. There was no correlation between cytomegalovirus presence and expression of survivin within odontogenic keratocysts. Conclusion: Survivin may contribute to the aggressive behavior of odontogenic keratocysts, and thus support the emerging opinion of their neoplastic nature.     

The Odontogenic Jaw Cysts： Analysis of the Clinical Parameters of 669 Cases

目的分析、比较三型牙源性颌骨囊肿的临床特点.方法收集20年间牙源性角化囊肿(odontogenic keratocyst,OKC)、根端囊肿(radicular cyst,RC)及含牙囊肿(dentigerous cyst,DC)的临床资料,对其性别构成、年龄分布、发病部位及临床表现等进行比较研究.结果1)三型颌骨囊肿的男女之比分别为OKC 1.6∶1,RC 1.4∶1,DC 4.1∶1(χ2检验,P＜0.005).2)除DC未见于70岁以上年龄段外,几乎各年龄段均见三型颌骨囊肿的发生,三型囊肿组间及组内的年龄分布均有显著性差异(χ2检验,P＜0.005).OKC及RC20～29岁年龄段患病人数最多,分别占各年龄段患病人数的27%及20%;DC10～19岁年龄段患病人数最多,占各年龄段患病人数的29%.3)颌骨的任一部位均见三型颌骨囊肿的发生,但发生频率不同,三型颌骨囊肿组间及组内发病部位的分布有显著性差异(χ2检验,P＜0.005).4)OKC有137例合并感染,感染率39%;RC48例合并感染,感染率24%;DC18例合并感染,感染率16%,三型间有显著性差异(χ2检验,P＜0.005).结论1)男性较女性更易发生牙源性颌骨囊肿.2)不同的年龄段,对OKC、RC及DC的易感性不同.OKC及RC发生的高峰期均为20～29岁年龄段;DC发生的高峰期为 10～19岁年龄段.3)不同的颌骨部位,对OKC、RC及DC的易感性不同.OKC好发于下颌磨牙区,其次为下颌双尖牙区;RC及DC则好发于上颌前牙区.4)感染症状的出现,对OKC、RC及DC彼此间的鉴别诊断具一定临床意义.     

The immunoprofile of odontogenic keratocyst (keratocystic odontogenic tumor) that includes expression of PTCH, SMO, GLI-1 and bcl-2 is similar to ameloblastoma but different from odontogenic cysts

Background:  The aggressive biological behavior of odontogenic keratocysts (OKCs), unlike that of other odontogenic cysts, has argued for its recent re-classification as a neoplasm, 'keratocystic odontogenic tumor'. Identification of mutations in the PTCH gene in some of the OKCs that were expected to produce truncated proteins, resulting in loss of control of the cell cycle, provided additional support for OKCs having a neoplastic nature.
Methods:  We investigated the immunohistochemical expression of the sonic hedgehog (SHH) signaling pathway-related proteins, PTCH, smoothened (SMO) and GLI-1, and of the SHH–induced bcl-2 oncoprotein in a series of primary OKC (pOKC), recurrent OKC (rOKC) and nevoid basal cell carcinoma syndrome-associated OKCs (NBCCS-OKCs), and compared them to solid ameloblastomas (SAMs), unicystic ameloblastomas (UAMs), 'orthokeratinized' OKCs (oOKCs), dentigerous cysts (DCs) and radicular cysts (RCs).
Results:  All studied lesions expressed the SHH pathway-related proteins in a similar pattern. The expression of bcl-2 in OKCs (pOKCs and NBCCS-OKCs) and SAMs was significantly higher than in oOKCs, DCs and RCs ( P  <   0.001).
Conclusions:  The present results of the immunoprofile of OKCs (that includes the expression of the SHH-related proteins and the SHH-induced bcl-2 oncoprotein) further support the notion of OKC having a neoplastic nature. As OKCs vary considerably in their biologic behavior, it is suggested that the quality and quantity of interactions between the SHH and other cell cycle regulatory pathways are likely to work synergistically to define the individual phenotype and corresponding biological behavior of this lesion.     

Immunohistochemical analysis of P53 protein in odontogenic cysts

The p53 is a well-known tumor suppressor gene, the mutations of which are closely related to the decreased differentiation of cells. Findings of studies on immunohistochemical P53 expression in odontogenic cysts are controversial. The present study was carried-out to investigate the immunohistochemical expression of P53 protein in odontogenic cysts. Thirty paraffin blocks of diagnosed odontogenic cysts were processed to determine the immunohistochemical expression of P53 protein. Nine of the 11 odontogenic keratocysts (81.8%) expressed P53, one of three dentigerous cyst cases expressed P53, while none of the 16 radicular cysts expressed P53 protein. The findings of the present work supported the reclassification of OKC as keratocystic odontogenic tumor.     

The differential expression pattern of BMP-4 between the dentigerous cyst and the odontogenic keratocyst

BACKGROUND: Bone morphogenic protein-4 (BMP-4) is widely expressed in oral cavity and involved in tooth morphogenesis, cellular differentiation and proliferation. The purpose of this study was to compare the difference in expression pattern of BMP-4 in odontogenic keratocysts (OKC) and dentigerous cysts (DC). METHODS: We evaluated 77 cysts, OKC (n = 34) or DC (n = 43). The average age of patients with OKC was 29.5 +/- 14.4 and that of patients with DC was 36.1 +/- 19.4. The male to female ratio was 20:14 for OKC and 27:16 for DC. Ten cases of OKC were recurrences. Expression of BMP-4 was determined by immunohistochemistry and in situ hybridization. RESULTS: The intensity scales were (-) for invisible or trace staining, (+) for visible staining, and (++) for dense, strong staining. OKCs exhibited the following staining patterns: the epithelium in 15/34 specimens and the mesenchymal cells in 17/34 specimens showed (++) stain. In contrast, the staining pattern of DC was (-) for epithelium in 37/43 specimens. The mesenchymal cells showed (-) degree staining in 30/43 specimens. The difference between the groups studied was significant (P < 0.001 in epithelium and mesenchymal cells). When recurrent and non-recurrent OKC were compared BMP-4 was expressed more intensely in the recurrent cases (P = 0.036 in epithelium). The difference in BMP-4 expression in mesenchymal cells was not significant. In situ hybridization demonstrated positive mRNA probes to BMP-4 were localized in epithelium and mesenchymal cells of OKCs and DCs. CONCLUSIONS: BMP-4 was expressed more intensely in OKC when compared with DC, and was more intensely expressed in recurrent cases.     

Expression of basement membrane components in odontogenic cysts

OBJECTIVE: To compare the expression of basement membrane components (BMCs), including laminins 1 and 5, collagen type IV, and fibronectin in odontogenic keratocysts (OKCs) with dentigerous cysts (DCs) and radicular cysts (RCs). MATERIALS AND METHODS: Basement membrane components were analysed in 20 OKCs, 20 DCs and 20 RCs using an immunohistochemical technique. RESULTS: Odontogenic keratocysts, DCs and RCs showed positive reaction to all BMCs studied, with different distributions and intensity. OKCs showed continuous linear deposits for laminins 1 and 5 but two staining patterns (continuous and discontinuous) for collagen type IV and fibronectin. DCs exhibited continuous linear deposits for laminins 1 and 5 and collagen type IV but a discontinuous linear deposit for fibronectin. RCs displayed similar results to DCs for laminin 1, collagen type IV and fibronectin. Laminin 5 in RCs had two staining patterns. Constant results in all cysts were strong intensity for laminin 1 and moderate intensity for laminin 5. CONCLUSIONS: Substantial differences in the expression of BMCs among studied cysts were not observed, suggesting that the separation of the epithelial lining in OKCs is not associated with the existence of these proteins.     

Calretinin expression in odontogenic cysts

Calretinin is a calcium-binding protein with a possible role as a calcium buffer, calcium-sensor, or regulator of apoptosis. Calretinin is expressed in neural tissue, is a specific marker of mesothelial cells, and has been demonstrated in the odontogenic epithelium during odontogenesis in rat molar tooth germs. Moreover, it has been found to be expressed in a high proportion of solid, unicystic, and multicystic ameloblastomas, whereas, on the contrary, no positive staining has been found in odontogenic keratocysts, residual cysts, and dentigerous cysts. The purpose of this study was to evaluate calretinin expression in radicular cysts, follicular cysts, orthokeratinized keratocysts, and parakeratinized keratocysts. A total of 70 odontogenic cysts, 24 radicular cysts, 24 follicular cysts, and 22 odontogenic keratocysts (10 orthokeratinized keratocysts, 12 parakeratinized keratocysts) were evaluated. All the radicular cysts, follicular cysts, and orthokeratinized keratocysts were negative. However in 8 of 12 parakeratinized keratocysts, there was a positivity to calretinin in the parabasal-intermediate layers of the cyst epithelium. This positivity to calretinin in the parabasal layers in parakeratinized keratocysts, similar to that found for other markers like PCNA and p53, could point to an abnormal control of the cell cycle and could help to explain the differences in the clinical and pathologic behavior of odontogenic keratocysts, in particular the differences found between orthokeratinized keratocysts and parakeratinized keratocysts.