[Immunohistochemical evaluation of p53 and ki-67 expression in selected developmental and inflammatory odontogenic cysts]

It seems that different growth mechanisms and biologic behaviors of odontogenic cysts are related to different expressions of various proteins and molecules. The purpose of this study was to determine the expression of p53 and ki-67 in radicular cysts [RC], odontogenic keratocysts [OKC], inflamed [IDC] and noninflamed dentigerous cysts [NIDC]. In this cross-sectional descriptive study, 13 RCs, 10 NIDCs, 15 IDCs and 19 cases of OKC were selected and stained for p53 and ki-67. The sides were evaluated by light microscopy [x400 magnification] and brown-staining cells were counted. Data were analyzed by Mann-Whitney and Kruskal Wallis tests. P53 expression was not observed in any cases of RCs and NIDCS. This marker was seen in 6.7% IDCs and 57.9% of OKCs with an average of 0.27=/-1.03 and 17.3 +/- 27.68. There was a statistically significant difference between OKC and other cysts regarding the expression of this marker [p=0.006]. Ki-67 expression was observed in 84.6%, 73.7%, 66.6% and 44% of RCs, OKCs, IDCs, and NIDCs and NIDCs, respectively. A significant difference existed between OKC and NIDC, and also NIDC and IDC [p=0.048] and radicular cysts and inflamed dentigerous cysts [p=0.046]. Based on the results of this study, expression of p53 and ki-67 is related and growth potential of odontogenic cysts

17 Beta-estradiol and progesterone upregulate cyclooxygenase-2 expression in the human gingival fibroblasts

Gingivitis is associated with 60-75% of all pregnancies and elevated levels of 17beta -estradiol and progesterone is known to increase gingival inflammation and the proinflammatory prostaglandins in the human gingiva. Since cyclooxygenase-2 [COX-2] is an inducible enzyme responsible for the production of prostaglandins at the sites of inflammation, it is plausible to hypothesize that 17beta - estradiol and progesterone could contribute to gingival inflammation by upregulation of COX-2 expression and subsequent prostaglandin formation. To examine this hypothesis, primary cultures of human gingival fibroblasts [HGFs] from either sex were established. The cells were treated with different concentrations [10-5, 10-7, and 10-9 M] of 17beta -estradiol and progesterone, and expression of COX-2 protein was detected immunocytochemically. The growth potential and proliferation of these cells were studied using trypan blue exclusion method and MTT assay. The results show that both 17beta -estradiol and progesterone upregulate COX-2 expression in the HGFs significantly. In addition, progesterone is more effective than 17beta -estradiol to induce COX-2 expression at 10-5M but not at lower concentration [10-9M]. Furthermore, cells prepared from either sex do not show any difference in COX-2 expression following hormone treatment and neither hormones show any changes in proliferation of these cells. In conclusion, the results of this investigation clearly illustrate significant regulatory effects of 17beta -estradiol and progesterone on COX-2 expression in the cultured HGFs. Thus, one possible pathogenetic mechanism of the female sex hormone-associated gingivitis in vivo may be the synthesis of proinflammatory prostaglandins via upregulation of COX-2 expression by gingiva in response to elevated levels of circulating estrogens and progesterone

Evaluation of platelet-rich plasma in combination with deproteinized bovine bone mineral in the rabbit cranium; A pilot study

Reconstruction methods are an essential prerequisite for functional rehabilitation of the stomatognathic system. Platelet-rich plasma [PRP] offers a new and potentially useful adjunct to bone substitute materials [e.g. Xenografts] in oral and maxillofacial bone and implant reconstructive surgery. An animal study was carried out to investigate the influence of PRP on the regeneratio of non-critical sized bony defects, treated with Deproteinized Bovine Bone Mineral [DBBM]. Eight New Zealand white rabbits were included in this randomized, pilot study. Three equal cranial bone defects [3×6 mm] were created and immediately grafted with DBBM and PRP+DBBM; one of them was left unfilled to serve as a control. The defects were evaluated using histologic and histomorphometric analysis at 2, 4, 8 and 12 weeks. The histomorphometric findings showed a significant increase in bone area and trabecular maturity in experimental defects as compared to the control at 4, 8 and 12 week intervals. A significant increase in bone formation was seen with the addition of PRP to DBBM at 2, 4 and 8 week intervals. At 12 weeks, the level of bone formation was similar between the two groups. There was also a significant increase in the rate of biodegradation of the DBBM particles with the addition of PRP at 2, 4, 8 and 12 weeks. No foreign body reaction and severe inflammation was seen in any of specimens. Within the limitations of this pilot study, it was concluded that the addition of PRP to Xenogenic bone substitute material in non-critical-sized defects of the rabbit cranium showed a histomorphometric increase in bone formation [until the 8th week of healing] and a greater amount of biomaterial degradation throughout the study period