Platelet-rich plasma (PRP), which is obtained by centrifuging autologous blood, contains a large number of platelets. When platelets are activated using substances such as thrombin, ƒ¿ granules release platelet released growth factor (PRGF) such as platelet-derived growth factor (PDGF) and transforming growth factor-ƒÀ (TGF-ƒÀ). Since these growth factors promote proliferation and differentiation of cells that are required for tissue regeneration, PRP has been used for bone and periodontal tissue regeneration in clinical dentistry. In the present study, we investigated the changes in PDGF-AB levels before and after platelet activation using ELISA. In addition, cellular proliferation was investigated by adding platelet released supernatant (PRS) produced by activating platelets of PRP to mesenchymal stem cell (MSC) culture media using MTS assay. The results showed that the level of PDGF-AB in PRS was 5.31 times higher than that before platelet activation. Furthermore, adding PRP or PRS significantly promoted MSC proliferation compared to the control, and adding PRS enhanced cellular proliferation in a dose-dependent manner from days 1 to 4 of culture. This study suggested that activation of platelets in PRP releases and concentrates PRGF, and that adding PRS to MSC promotes early cellular proliferation of MSC.
Allelic imbalance or loss of heterozygosity (LOH) and microsatellite instability (MSI) have been used to identify regions on chromosomes that may contain putative tumor suppressor genes. To obtain a detailed understanding of genetic alterations in oral cancer, 10 highly polymorphic markers mapped on chromosome 2 were used to examine 25 cases of oral squamous cell carcinoma (SCC). With these, we analyzed chromosome 2q for LOH in 25 primary oral SCCs and constructed a deletion map for this arm of the chromosome. LOH was detected in 16 (64%) of the 25 informative samples at one or more of the loci examined. MSI was observed in 5 (20%) of the 25 cases. Among the loci examined, LOHs were restricted to D2S1328 and D2S206 on chromosomes 2q14-21 and 2q36, respectively, with the former locus showing a rate of 5 (20.8%) and the latter a rate of 6 (25%) of the 24 informative cases. These observations taken in conjunction with data from 40 former cases analyzed at our laboratory suggest that the high incidence of LOH at chromosome 2q is associated with carcinogenesis of oral SCC. The regions that comprise the D2S1328 and D2S206 loci may play an important role in the development of oral SCC, perhaps containing sites that harbor a putative tumor suppressor gene.
PURPOSE:To determine the importance of margin design on fracture strength and pattern of endodontically-treated teeth with 0 mm of coronal tooth structure.METHODS:Using the CELAY system (MIKRONA, Switzerland), 168 human maxillary central incisors, identical in size and shape, were replicated from bovine teeth. The fracture strength and pattern of 5 types of margin design, three core materials and two levels of remaining coronal tooth structure were examined after 24 hours of water immersion (37 degrees C) under 16 conditions and 83 hours under 6 conditions without cyclic loading, as well as after 83 hours of water immersion with 300,000 cyclic loading under 6 conditions.RESULTS:In the case of cast metal post-and-cores with 0 mm of coronal tooth structure, both beveled and shouldered shoulder margin designs resulted in a higher fracture strength than chamfer and shoulder ones, achieving almost the same strength of chamfer margin design with 1 mm of coronal tooth structure. In addition, pinhole preparation on the root surface increased the fracture strength of chamfer margin design to the level of those of the above-mentioned two desirable margin designs. From a fracture pattern viewpoint, however, all margin designs were unsuitable for re-restoration of the tooth.CONCLUSIONS:Both beveled and shouldered shoulder margin designs improve fracture strength of endodontically-treated teeth with 0mm of remaining coronal tooth structure.
PURPOSE The purpose of this study was to determine whether rotation and translation of the condyle were useful parameters for identifying causes of limitation of mouth opening in patients with temporomandibular disorders (TMD). METHODS In 7 healthy volunteers and 55 patients with TMD, rotation and translation of the condyle were measured using a 6 degree-of-freedom jaw movement tracking device. Patients were divided into two groups: those who could open their mouth 40 mm or greater, and those who could not open their mouth 40 mm. In each group, the relationship of rotation and translation of the condyle to maximum mouth opening, condition of the articular disc, and pain was determined. RESULTS Both correlations between maximum mouth opening and rotation and translation of the condyle were strong, especially the former correlation. There was no marked difference in the distribution of range of mouth opening, and rotation and translation of the condyle with respect to condition of the artticular disc. Muscle pain was associated with reduced mouth opening. Even in patients without limited mouth opening, their range of mouth opening was actually reduced when they had muscle pain. Among the patients with limited mouth opening, joint pain correlated to limited translation of the condyle. However, in patients with Wo-Wo condition of articular disc, their translation of the condyle was not limited even with joint pain, but it was limited with muscle pain. CONCLUSIONS Rotation of the condyle indicated strong correlation with muscle pain, and so is a useful parameter for estimating treatment methods by a surgical approach. On the other hand, translation of the condyle showed variations in correspondence with combinations of several factors such as opening limitation, condition of the articular disc, and pain.
