Nuclear fractal dimension in oral squamous cell carcinoma: a novel method for the evaluation of grading, staging, and survival.

Fractal dimension (FD) in tissue specimens from patients with oral squamous cell carcinoma (OSCC) was evaluated. FD values in different stages of OSCC, and the correlations with clinicopathological variables and patient survival were investigated. Histological sections from OSCC and control non-neoplastic mucosa specimens were stained with hematoxylin-eosin for pathological analysis and with Feulgen for nuclear evaluation. FD in OSCC groups vs. controls revealed statistically significant differences (P < 0.001). In addition, a progressive increase of FD from stage I and II lesions and stage III and IV lesions was observed, with statistically significant differences (P = 0.003). Moreover, different degrees of tumor differentiation showed a significant difference in the average nuclear FD values (P = 0.001). A relationship between FD and patients' survival was also detected with lower FD values associated to longer survival time and higher FD values with shorter survival time (P = 0.034). These data showed that FD significantly increased during OSCC progression. Thus, FD could represent a novel prognostic tool for OSCC, as FD values significantly correlated with patient survival. Fractal geometry could give insights into tumor morphology and could become an useful tool for analyzing irregular tumor growth patterns.

Blood vessels are concentrated within the implant surface concavities: a histologic study in rabbit tibia.

Angiogenesis plays a key role in bone formation and maintenance. Bone formation has been reported to initiate in the concavities rather than the convexities in a hydroxyapatite substratum and the implant threads of dental implants. The aim of the present study was to evaluate the number of the blood vessels inside the concavities and around the convexities of the threads of implants in a rabbit tibia model. A total of 32 thread-shaped implants blasted with apatitic calcium phosphate (TCP/HA blend) (Resorbable Blast Texturing, RBT) (Maestro, BioHorizons(®), Birmingham, AL, USA) were inserted in 8 rabbits. Each rabbit received 4 implants, 2 in the right and 2 in left tibia. Implants were retrieved after 1, 2, 4, and 8 weeks and treated to obtain thin ground sections. Statistically significant differences were found in the number of vessels that had formed in the concavities rather than the convexities of the implants after 1 (p = 0.000), and 2 weeks (p = 0.000), whilst no significant differences after 4 (p = 0.546) and 8 weeks (p = 0.275) were detected. The present results supported the hypothesis that blood vessel formation was stimulated by the presence of the concavities, which may provide a suitable environment in which mechanical forces, concentrations and gradients of chemotactic molecules and blood clot retention may all drive vascular and bone cell migration.

Osteocyte density in the peri-implant bone of implants retrieved after different time periods (4 weeks to 27 years).

Bone tissue is characterized by a constant turnover in response to mechanical stimuli, and osteocytes play an essential role in bone mechanical adaptation. However, little to no information has been published regarding osteocyte density as a function of implantation time in vivo. The aim of this retrospective histological study was to evaluate the osteocyte density of the peri-implant bone in implants retrieved because of different reasons in a time period from 4 weeks to 27 years. A total of 18 samples were included in the present study. Specimens were divided into 3 groups depending on the loading history of the implants: loading between 4 weeks and 7 months (group 1); loading between 1 and 5 years (group 2); loading between 14 and 27 years (group 3). All the samples were histologically evaluated and osteocyte density was obtained using the ratio of the number of osteocytes to the bone-area (mm(2) ). The osteocyte density values significantly increased in the Group 2 (1-5 years) compared with Group 1 (4 weeks-7 months), and significantly decreased in the Group 3 (14-27 years) compared to Group 2. No significant differences were detected between Group 1 and Group 3. The decrease in osteocyte density observed in samples that were in vivo for long periods of time under loading is possibly because of the fact that once the bone structure is well aligned and biomechanically competent, a lower number of osteocytes are necessary to keep the tissue homeostasis under loading.

Matrix metalloproteinases 2, 3, 8, 9, and 13 in the peri-implant soft tissues around titanium and zirconium oxide healing caps.

PURPOSE: This human study sought to compare, from an immunohistochemical point of view, matrix metalloproteinases (MMPs) 2, 3, 8, 9, and 13 in the soft tissues around titanium and zirconium oxide healing caps. MATERIALS AND METHODS: Five patients participated in this study. All patients received 3.8 × 11-mm dental implants, which were left to heal in a nonsubmerged (single-stage) mode. Healing caps (3.8 mm in diameter and 3.0 mm in height) were inserted in all implants. Half of the implants were randomly supplied with standard, prefabricated caps of commercially pure titanium (control), while the other half were randomly provided with zirconium oxide caps (test). After a 6-month healing period, gingival biopsy specimens were obtained with a circular scalpel around the healing caps of both groups, without unscrewing or removing the healing caps, and the samples underwent immunohistochemical processing for MMPs 2, 3, 8, 9, and 13. RESULTS: Statistically significant differences were found in the values of MMP-8 in the cells of the inflammatory infiltrate, with higher values for the titanium samples. Statistically significantly higher values were found, also in the titanium samples, for MMP-9 in the endothelial cells of the blood vessels. No statistically significant differences were found for any other MMPs. CONCLUSIONS: The present results showed that the soft tissues around titanium healing caps underwent a higher rate of restorative processes, most probably correlated to the MMP levels observed in the tissues.

Hemostasis control in endodontic surgery: a comparative study of calcium sulfate versus gauzes and versus ferric sulfate.

INTRODUCTION: Calcium sulfate (CaS) is a simple, biocompatible material with a long history of safe use in different fields of medicine. CaS is a rapidly resorbing material that leaves behind a calcium phosphate lattice, which promotes bone regeneration and hemostasis. The aim of this study was a clinical evaluation of the hemostatic effect of CaS hemi-hydrate (CaSO4), commonly known as plaster of Paris, in endodontic surgery. METHODS: Twenty-four patients with 31 periradicular lesions were enrolled in this study. The apical roots were exposed, and the bleeding would have made it difficult to correctly fill the root-end cavities. To avoid such an inconvenience, the teeth were divided into 3 groups. Hemostasis was attempted by using CaS in 11 teeth (group I), gauze tamponade in another 10 teeth (group II), or 20% ferric sulfate in the last 10 teeth (group III). RESULTS: Control of the bleeding was achieved in all teeth of group I, whereas in group II adequate hemostasis was achieved in 3 of 10 cases and in group III in 6 of 10 cases. CONCLUSIONS: The use of CaS completely eliminated the bleeding, with a very good level of hemostasis.

Histological and immunohistochemical evaluation of the peri-implant soft tissues around machined and acid-etched titanium healing abutments: a prospective randomised study.

A close spatial correlation has been described between the roughness of intraoral materials and the rate of bacterial colonisation. The aim of the present study in man was to conduct a comparative immunohistochemical evaluation of the inflammatory infiltrate, microvessel density, the nitric oxide synthases 1 and 3 and the vascular endothelial growth factor expression, the proliferative activity, and the B and T lymphocyte and histiocyte positivity in the peri-implant soft tissues around machined and acid-etched titanium healing caps. Ten patients participated in this study. The patients were enrolled consecutively. All patients received dental implants left to heal in a non-submerged mode. Healing caps were inserted in all implants. Half of the implants were supplied randomly with machined caps of titanium (control), while the other half were provided randomly with acid-etched titanium caps (test). After a 6-month healing period, a gingival biopsy was performed with a circular scalpel around the healing caps of both groups. The inflammatory infiltrate was mostly present in test specimens. Their extension was much larger than that of the control samples. A higher number of T and B lymphocytes were observed in test specimens. Higher values of microvessel density and a higher expression of vascular endothelial growth factor intensity were observed in the test samples. Furthermore, the Ki-67, NOS1 and NOS3 expression was significantly higher in the test specimens. All these results showed that the tissues around test healing caps underwent a higher rate of restorative processes, most probably correlated to the higher inflammation processes observed in these tissues.

Sinus lift with autologous bone alone or in addition to equine bone: an immunohistochemical study in man.

PURPOSE: The aim of the present study was to perform a comparative histological and immunohistochemical evaluation of microvessel density, vascular endothelial growth factor, and nitric oxide synthase (NOS) expression in sinus augmentation using autologous bone alone or in combination with equine bone. MATERIALS AND METHODS: Sixteen patients underwent sinus augmentation with autologous bone and a 50:50 mixture of autologous and equine bone. Control cores were harvested from preexisting nonaugmented bone under the sinus floor. The specimens were processed for immunohistochemistry. RESULTS: The greatest values of microvessel density were found in the sites grafted with autologous bone with significant differences between control versus autologous group (P < 0.01) and control versus autologous + equine group (P < 0.01). The higher and lower intensities of vascular endothelial growth factor and NOS3 expression were prevalent in the sites grafted with autologous bone with significant differences with the controls (P < 0.05). No significant differences (P > 0.05) were found in the NOS1 expression among the groups. CONCLUSION: The results obtained showed that the mixture of autologous and equine bone was biocompatible, and its use was associated with new blood vessels ingrowth during healing, which has been found to be extremely important for bone formation.

Immunohistochemical analysis of inflammatory infiltrate in aggressive and chronic periodontitis: a comparative study.

This immunohistochemical study evaluated the inflammatory infiltrate with its cluster differentiation markers (CD 4, CD 8, CD 20, and CD 68) in aggressive and chronic periodontitis gingival tissues in order to identify the specific cell distribution. Twenty-seven human gingival biopsies were obtained and analyzed. Fourteen patients were suffering from chronic periodontitis and six from aggressive periodontitis; seven patients with healthy gingiva were included as the control group. The specimens were immunohistochemically stained for anti-CD 4 (T helper cells), anti-CD 8 (T cytotoxic/suppressor), anti CD-20 (B plasma cells) and anti CD-68 (macrophages). Chronic periodontitis samples were mainly dominated by CD 4 and CD 8+ cells. On the contrary, in aggressive periodontitis patients all four cell types (CD 4, CD 8, CD 20 and CD 68 + cells, respectively) were remarkably increased. CD 20+ cells were significantly (p < 0.05) more prevalent in aggressive versus chronic periodontitis. The control samples expressed lower CD 4, CD 8, CD 20 and CD 68+ cells confirming a none inflammatory state. The present study demonstrates prevalence for CD 20+ cells in aggressive periodontitis lesions. However, further studies need to be performed to confirm and identify a clear pattern of inflammatory cells and hereafter the mechanisms sustaining the disease.

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.

Immunoexpression of angiogenesis, nitric oxide synthase, and proliferation markers in gingival samples of patients with aggressive and chronic periodontitis.

BACKGROUND: In periodontal tissues, angiogenesis seems to be important for the maintenance of healthy tissues and in periodontal diseases. Angiogenesis is regulated through a complex interplay of molecular signals mediated by growth factors involving extracellular matrix remodeling, endothelial cell migration and proliferation, capillary differentiation and anastomosis. However, the influence of angiogenesis in the development, progression, and healing of periodontal lesions is currently under investigation. This immunohistochemical study evaluates the expression of vascular endothelial growth factor (VEGF), microvessel density (MVD), nitric oxide synthase (NOS) 1 and 3, and Ki-67 in gingival tissues of patients with aggressive and chronic periodontitis. METHODS: Twenty-seven human gingival biopsies were taken from patients with chronic periodontitis (n = 14 patients), generalized aggressive periodontitis (n = 6 patients), and healthy periodontia (n = 7 patients). The specimens were immunohistochemically stained for VEGF, MVD, NOS 1 and 3, and Ki-67. RESULTS: The levels of VEGF, MVD, NOS 1 and 3, and Ki-67 were found to be significantly different among groups (P >0.001). Patients with aggressive periodontitis had higher levels of these markers compared to those in patients with chronic periodontitis and healthy patients. CONCLUSIONS: The analysis demonstrates a higher expression of all immunologic markers particularly in subjects with aggressive periodontitis. In summary, the data from this pilot investigation suggests that VEGF is an important factor in the pathogenesis of the aggressive and chronic forms of periodontitis.

Inflammatory infiltrate, microvessel density, vascular endothelial growth factor, nitric oxide synthase, and proliferative activity in soft tissues below intraorally welded titanium bars.

BACKGROUND: The aim of the present study is a comparative evaluation of inflammatory infiltrate, microvessel density, vascular endothelial growth factor, nitric oxide synthase, and proliferative activity in soft tissues below intraorally welded titanium bars. METHODS: Twenty-two patients participated in this study. All patients carried immediately loaded one-stage titanium implants splinted with intraorally welded titanium bars. Each patient underwent two gingival biopsies, a control biopsy harvested from an area of mucosa 5 mm away from the titanium bar and a test biopsy from the mucosa below the titanium bar, which were histologically and immunohistochemically processed. RESULTS: No fractures or radiographically detectable alterations of the welded frameworks were present. In all the cases examined, the average of the modified plaque index was 1, no suppuration or bleeding on probing was present, and probing depth was < or =3 mm. However, the immunohistochemical analysis revealed some differences. The inflammatory infiltrate was mostly present in test sites and its extension was much larger than in control sites. Statistically significant differences were found in microvessel density and Ki-67 expression among control and test groups (P <0.0001). The high intensity of vascular endothelial growth factor, nitric oxide synthase 1, and nitric oxide synthase 3 expression were mainly detected in the test group, whereas the low intensities were mostly expressed in controls, with statistically significant differences (P <0.0001). CONCLUSIONS: In the present study, the immunohistochemical analysis shows that the tissues below the titanium bars underwent a higher rate of inflammatory and reparative processes. However, further long-term studies, where clinical and immunohistochemical data are collected in parallel, should be conducted for a better understanding of the expression pattern of inflammation markers.

Detection of Helicobacter pylori in saliva and esophagus.

The route of Helicobacter pylori transmission remains unclear and the currently suggested route is person-to-person transfer by faecal-oral and oral-oral mode. The aim of this study was to verify the presence of H. pylori in esophagus and saliva of humans. Saliva samples, mucosal biopsies from esophagus, gastric antrum and fundus were collected from 19 patients with positive Urea Breath Test (UBT). Gastric biopsies were used for H. pylori colture and antimicrobial susceptibility tests whereas saliva samples were collected to detect H. pylori with a Nested-PCR targeting 16S rRNA gene as well as esophagus biopsies which were also investigated with immunohistochemical staining. Helicobacter pylori was isolated in 18 patients both in gastric antrum and fundus. The molecular analysis, confirmed by comparative sequences evaluation, gave positive results in all saliva and esophageal samples whereas the immunohistochemistry revealed the presence of H. pylori in 15.8% (3/19) of the esophagus samples. Our data suggest that saliva and esophagus may be considered reservoirs for H. pylori in humans and emphasize the need to use more susceptible techniques for H. pylori detection, in particular in over-crowded sites. Identification of the transmission route of H. pylori is crucial in developing an effective plan of surveillance by finding new means of disease management.

Alveolar ridge regeneration with equine spongy bone: a clinical, histological, and immunohistochemical case series.

BACKGROUND: In the case of localized ridge atrophy, a ridge augmentation procedure, with the use of bone substitutes and barrier membranes, may then be necessary. PURPOSE: The aim of the present study was a clinical, histological, and immunohistochemical evaluation of an equine spongy bone in alveolar ridge augmentation procedures. MATERIALS AND METHODS: Five patients showing horizontal mandibular ridge defects participated in this study. A ridge augmentation was performed through an onlay apposition of equine bone covered by a titanium-reinforced membrane. After 6 months of healing, five bone cores from nonaugmented sites (control) and five from augmented sites (test) were retrieved. RESULTS: In test sites, no postoperative complications occurred. Horizontal bone width increased from 24 to 37 mm. In control sites, the newly formed bone represented 33%, and in test sites, 35% of the total area. The mean value of the microvessel density was 25.6 +/- 3.425 per mm(2) in controls, while 33.3 +/- 2.5 vessels per mm(2) in the test sites were found (p < .05). Both groups showed a high intensity (++) of vascular endothelial growth factor expression in the newly formed bone, while a low intensity (+) was found in the mature bone. CONCLUSION: Equine bone appeared to be biocompatible and to be associated with new vessel ingrowth. Within the limits of the small sample size, the present study indicated that equine bone could be used in mandibular ridge augmentations.

Expression of transforming growth factor beta1 in ameloblastomas.

The aim of the present study was to compare the expression of transforming growth factor (TGF) beta1 in ameloblastomas (AMs) with different risk of recurrence by immunohistochemistry. A total of 29 cases of AMs were evaluated. The tumors were divided into 2 groups: group A (10 cases) composed of unicystic and peripheral AMs, associated with a low risk of recurrence, and group B (19 cases) composed of solid AMs, associated with a high risk of recurrence. Statistical evaluation showed significant differences between groups A and B lesions, with higher values of positivity for TGF-beta1 in stromal cells in group B tumors (P = 0.0308). No statistically significant differences of immunoreactivity were found in vessels and odontogenic epithelium between the 2 groups. The increased TGF-beta1 expression in tumors with a high risk of recurrence could be explained with the fact that although TGF-beta acts as a potent tumor suppressor in the early stages of tumor progression, later it seems to enhance the invasive phenotype of the tumor.

P16 expression in odontogenic tumors.

AIMS AND BACKGROUND: The aim of the study was to examine the immunohistochemical expression of a cell-cycle-related factor (p16) in order to elucidate its role in the growth and diffusion of odontogenic tumors. STUDY DESIGN: Thirty-six odontogenic tumors were divided into two groups according to their clinical behavior: group A and group B composed of tumors at low and high risk of recurrences, respectively. The ANOVA test was used to detect differences between the two groups. RESULTS: p16 was expressed in both groups, but with different localization. A statistically significant difference was found in p16 expression of peripheral cells, with an increase in the expression in group B compared to group A (P < 0.05). In addition, there was no significant difference in p16 positive expression of the central cells of odontogenic tumors, which was high in both groups. CONCLUSIONS: The present data show a correlation between p16 expression and the biological behavior of odontogenic tumors.

Loss of expression of TGF-beta1, TbetaRI, and TbetaRII correlates with differentiation in human oral squamous cell carcinomas.

Despite advances in biological and molecular characteristics, the prognosis of oral squamous cell carcinomas is still very unfavourable and is based on the classical clinicopathological parameters. However, tumors with similar clinicopathological characteristics may differ dramatically in their clinical outcome. Thus, the identification of novel prognostic factors is necessary to improve prognostic and therapeutic approaches. Transforming growth factor-beta1 (TGF-beta1) is a potent growth inhibitor of epithelial cell proliferation, thus, inactivation of TGF-beta1 signalling may play a role in cancer. The expression levels of TGF-beta1 and its type I and type II receptors (TbetaRI and TbetaRII) were assessed by immunohistochemical and Western blot analyses in 22 oral squamous cell carcinoma lesions, in their normal adjacent mucosa and in the squamous carcinoma cell lines FaDu and CAL27. Immunohistochemistry on 22 oral carcinomas and case-matched normal oral mucosae demonstrated that TGF-beta1, TbetaRI, and TbetaRII were intensively and homogeneously expressed in all normal epithelia. In contrast, TGF-beta1 and its receptors were significantly reduced in poorly (G3) differentiated tumors as compared to moderately (G2) and well differentiated (G1) lesions (p=2.8 x 10(-3), p=1.3 x 10(-3), p=2.8 x 10(-3) and p=1.3 x 10(-3), respectively). The progressive reduction of the expression levels was confirmed by Western blotting. The oral squamous carcinoma cell lines Cal27 and FaDu demonstrated a reduced and a lack of TbetaRI expression, respectively. A significant decrease of TbetaRII expression, as compared to Cal27 cells, was shown in FaDu cells. Thus, the decreased expression of TbetaRII combined with the absence of TbetaRI could account for the resistance of FaDu cells to the growth-inhibiting effect of TGF-beta1. TGF-beta1 and TGF-beta1 receptor expression significantly decreased as tumors became less differentiated and thus more aggressive, suggesting a functional role of these molecules in oral tumor progression.

CD10 expression in stromal cells of ameloblastoma variants.

OBJECTIVE: We performed an immunohistochemical study in a series of ameloblastomas with different histology to explore the existence of a correlation between CD10 immunoreactivity in peritumoral stromal cells and the type of ameloblastoma with a high risk of local recurrence. STUDY DESIGN: A total of 45 ameloblastomas (18 unicystic [UA], 4 peripheral [PA], 23 solid/multicystic [SA]) were evaluated. Cases showing immunoreactivity for CD10 in < and > or =10% of stromal cells around tumoral epithelial islands, were considered, respectively, negative and positive. Correlations between stromal CD10 expression and histopathologic types with low and high risk of recurrence were evaluated by statistical analysis. RESULTS: SA cases showed a significantly higher percentage of stromal CD10-positive cells than the UA and PA variants. A strong intensity of immunostaining was observed only in SA. CONCLUSIONS: Our results suggest that CD10 expression might be associated with stromal invasion in ameloblastoma variants with a high risk of recurrences.

Maspin expression in oral squamous cell carcinoma.

Maspin (mammary serine protease inhibitor) is a member of the serpin superfamily of protease inhibitors and it has a role as a tumor suppressor. Maspin has been reported to be important in processes relevant to tumor growth and metastasis such as cell invasion, angiogenesis, and apoptosis. A high expression of maspin was correlated with better rates of survival and absence of nodal metastases in head and neck squamous cell carcinoma. In contrast, some studies have shown that maspin overexpression is correlated with a poor prognosis in pancreatic and ovarian cancers and in lung adenocarcinoma. The aim of this study was an immunohistochemical evaluation of the maspin expression in oral squamous cell carcinoma and thus 89 patients were evaluated. Maspin expression in oral squamous cell carcinoma was significantly associated with the tumor differentiation grade (chi test: P = 0.0318) and the lymph node status (chi test: P < 0.005), but not with the tumor stage (chi test: P = 0.666). Metastatic involvement of lymph nodes was observed more frequently in maspin-negative cases than in tumors with more than 5% of positive cells (P = 0.0024). The present results confirm that maspin expression predicts a better prognosis in oral squamous cell carcinoma and that maspin probably plays a role in tumor progression.

Microvessel density in sinus augmentation procedures using anorganic bovine bone and autologous bone: 3 months results.

PURPOSE: This study was an immunohistochemical evaluation of microvessel density (MVD) in sinus augmentation procedures with autologous bone and anorganic bone (Bio-Oss). MATERIALS AND METHODS: Twenty-four patients (14 men and 10 women - mean age of 48 years with a range from 34 to 53 years) participated in this study. All the patients presented a maxillary partial unilateral edentulism involving the premolar/molar areas, with a residual alveolar ridge height of about 4 to 5 mm. Twelve patients received sinus augmentation procedures with 100% autologous bone; 100% Bio-Oss was used in the other 12 patients. Endosseous implants were inserted after a mean period of 3 months. As control, the portions of preexisting subantral bone were used. The mean value of the MVD in control bone was 23.4 +/- 1.3. The mean value of the MVD in the sinuses augmented with autologous bone was 29.0 +/- 2.4. The mean value of the MVD in the sinuses augmented with Bio-Oss was 23.8 +/- 2.2. RESULTS: The statistical analysis showed that the differences of the MVD between control bone and sinuses augmented with Bio-Oss were not statistically significant (P = 0.52), while the difference of the MVD between sinuses augmented with autologous bone and those augmented with Bio-Oss was statistically significant (P = 0.0008). CONCLUSIONS: Autologous bone may act not only as a passive filling material in bone defects but may also release osteogenic growth factors; and particles of autologous bone seem to contain vital osteoprogenitor cells.

KAI-1 protein expression in odontogenic cysts.

The KAI-1 tumor suppressor gene is widely distributed in normal tissues and its down-regulation may be correlated with the invasive phenotype and metastases in several different epithelial tumors. The aim of the present study was an evaluation of KAI-1 expression in radicular cysts (RC), follicular cysts (FC), orthokeratinized keratocysts (OOKC), and parakeratinized keratocysts (POKC). Eighty-five odontogenic cysts, 28 RC, 22 FC, and 35 OKC (16 OOKC, 19 POKC) were selected. All the POKC were negative and only four of 16 of the OOKC were positive for KAI-1. On the contrary, all RC and FC cases were positive and immunoreactivity for KAI-1 was detected throughout all the layers of the cyst epithelium. The lack of KAI-1 expression in POKC could help to explain the differences in the clinical and pathologic behavior of OKC and, according to what has been reported for epithelial tumors, could be related to the increased aggressive behavior and invasiveness of OKC.