Influence of the number of insertions and removals of telescopic zirconia/alumina crowns on retentive force and settling.

Telescopic crowns made from zirconia/alumina can be manufactured using computer-aided design/computer-aided manufacturing systems. For their successful clinical use, a suitable retentive force must be maintained over an extended period. However, it is unclear how retentive force and secondary crown settling change after repeated crown insertion and removal. The aim of the present study was to investigate the changes in retentive force and secondary crown settling of telescopic crowns made from zirconia/alumina. Primary crowns with tapers of 2° and 4° were used. Repeated insertion and removal tests were performed for 10,000 cycles at a cyclic load of 50 N. The loads applied when measuring retentive force and settling were 50 and 100 N. The number of insertions and removals had a significant effect on retentive force and settling at both loads (p<0.01). Taper also had a significant effect on retentive force and settling at both loads (p<0.01).

Relationships between thermal dose parameters and the efficacy of definitive chemoradiotherapy plus regional hyperthermia in the treatment of locally advanced cervical cancer: data from a multicentre randomised clinical trial.

PURPOSE: To evaluate the contribution of the thermal dose parameters during regional hyperthermia (HT) treatment to the clinical outcomes in patients with cervical carcinoma (CC) who received chemoradiotherapy (CRT) plus HT. MATERIALS AND METHODS: Data from a multicentre randomised clinical trial of concurrent CRT + HT vs. CRT alone were used to evaluate the efficacy and safety of this combination therapy in the CC patients. The intrarectal temperatures of patients undergoing HT were recorded. The complete thermal data of 47 (92%) of the 51 patients in the CRT + HT group were available for the thermal analysis. Thus, 47 patients who received CRT + HT were included in the present study. RESULTS: Among the patients who received CRT + HT, a higher CEM43T90 (≥1 min) value (a thermal dose parameter) was significantly associated with better local relapse-free survival in both univariate (p = 0.024) and multivariate (p = 0.0097) analyses. The disease-free survival of the patients with higher CEM43T90 (≥1 min) values tended to be better in comparison to patients with lower CEM43T90 (<1 min) value (p = 0.071). A complete response tended to be associated with the CEM43T90 (p = 0.056). Disease-free survival, local relapse-free survival and complete response rate for patients with higher CEM43T90 (≥1) were significantly better than those for patients with CRT alone (p = 0.036, p = 0.036 and p = 0.048). CONCLUSIONS: Dose-effect relationships between thermal dose parameters and clinical outcomes were confirmed in the CC patients treated with a combination of CRT + HT. This study also confirmed that HT with lower CEM43T90 is insufficient to achieve a significant hyperthermic sensitisation to CRT.

A multicentre randomised clinical trial of chemoradiotherapy plus hyperthermia versus chemoradiotherapy alone in patients with locally advanced cervical cancer.

PURPOSE: To evaluate the effectiveness of whole-pelvic hyperthermia (HT) added to standard chemoradiotherapy (CRT) in locally advanced cervical cancer (CC), by investigating the clinical response and survival of patients treated with cisplatin-based CRT vs. CRT with HT (CRT + HT). MATERIALS AND METHODS: This study was conducted at five hospitals in Japan between September 2001 and March 2015 in patients with the International Federation of Gynecology and Obstetrics stage IB (bulky)-IVA CC undergoing definitive CRT. After giving a written informed consent, patients were randomly allocated to two treatment groups: CRT and CRT + HT group. Overall survival (OS), disease-free survival (DFS), local relapse-free survival (LRFS), complete response (CR) rate and tolerability were evaluated. RESULTS: In total, 101 patients were treated. Patient characteristics, total dose of cisplatin and radiotherapy were similar for both groups. Although not statistically significant, the 5-year OS, DFS and LRFS in the CRT + HT group (77.8%, 70.8% and 80.1%, respectively) were better than those in the CRT group (64.8%, 60.6% and 71.0%, respectively). CR was significantly more likely to be achieved in patients in the CRT + HT group than in the CRT group (88% vs. 77.6%; adjusted odds ratio, 3.993; 95% confidence interval, 1.018-15.67; p = .047). CRT + HT was well tolerated and caused no additional acute or long-term toxicity compared with CRT alone. CONCLUSIONS: HT combined with CRT improved the CR rate of CRT in patients with locally advanced CC, however, could not improve survival outcomes. Further studies in larger samples are warranted.

Influence of atmospheric pressure low-temperature plasma treatment on the shear bond strength between zirconia and resin cement.

PURPOSE: Zirconia exhibits excellent strength and high biocompatibility in technological applications and it is has therefore been investigated for clinical applications and research. Before setting prostheses, a crown prosthesis inner surface is sandblasted with alumina to remove contaminants and form small cavities. This alumina sandblasting causes stress-induced phase transition of zirconia. Atmospheric-pressure low-temperature plasma has been applied in the dental industry, particularly for adhesives, as a surface treatment to activate the surface energy and remove contaminants. The purpose of this study was to examine the influence of atmospheric-pressure low-temperature plasma treatment on the shear bond strength between zirconia and adhesive resin cement. METHODS: The surface treatment method was classified into three groups: untreated (Cont group), alumina sandblast treatment (Sb group), and atmospheric-pressure low-temperature plasma treatment (Ps group). Adhesive resin cement was applied to stainless steel and bonded to zirconia. Shear adhesion tests were performed after complete hardening of the cement. Multiple comparisons were performed using a one-way analysis of variance and the Bonferroni method. X-ray diffractometry was used to examine the change in zirconia crystal structure. RESULTS: Statistically significant differences were noted between the control and Sb groups and between the control and Ps groups. In contrast, no statistically significant differences were noted for the Ps and Sb bond strength. Atmospheric-pressure low-temperature plasma treatment did not affect the zirconia crystal structure. CONCLUSIONS: Atmospheric-pressure low-temperature plasma treatment improves the bonding strength of adhesive resin cement as effectively as alumina sandblasting, and does not alter the zirconia crystal structure.

Application of Green Tea Catechin for Inducing the Osteogenic Differentiation of Human Dedifferentiated Fat Cells in Vitro.

Despite advances in stem cell biology, there are few effective techniques to promote the osteogenic differentiation of human primary dedifferentiated fat (DFAT) cells. We attempted to investigate whether epigallocatechin-3-gallate (EGCG), the main component of green tea catechin, facilitates early osteogenic differentiation and mineralization on DFAT cells in vitro. DFAT cells were treated with EGCG (1.25-10 µM) in osteogenic medium (OM) with or without 100 nM dexamethasone (Dex) for 12 days (hereafter two osteogenic media were designated as OM(Dex) and OM). Supplementation of 1.25 µM EGCG to both the media effectively increased the mRNA expression of collagen 1 (COL1A1) and runt-related transcription factor 2 (RUNX2) and also increased proliferation and mineralization. Compared to OM(Dex) with EGCG, OM with EGCG induced earlier expression for COL1A1 and RUNX2 at day 1 and higher mineralization level at day 12. OM(Dex) with 10 µM EGCG remarkably hampered the proliferation of the DFAT cells. These results suggest that OM(without Dex) with EGCG might be a preferable medium to promote proliferation and to induce osteoblast differentiation of DFAT cells. Our findings provide an insight for the combinatory use of EGCG and DFAT cells for bone regeneration and stem cell-based therapy.

Skeletal unloading alleviates the anabolic action of intermittent PTH(1-34) in mouse tibia in association with inhibition of PTH-induced increase in c-fos mRNA in bone marrow cells.

UNLABELLED: We analyzed the effect of unloading by tail suspension on the anabolic action of intermittent PTH in the tibia of growing mice. Unloading alleviated the PTH-induced increase of bone formation and accelerated bone resorption, consequently reducing bone mass. Reduction of the PTH-induced anabolic actions on bone was associated with unloading, which was apparently related to suppression of c-fos mRNA expression in bone marrow. INTRODUCTION: The effects of intermittent parathyroid hormone (PTH) administration on unloading bone have not been well elucidated at the cellular and molecular levels. We tested the effects of PTH on unloaded tibias of tail-suspended mice. MATERIALS AND METHODS: Eighty male C57BL/6J mice, 8 weeks of age, were divided into four groups with loading or unloading and administration of PTH (40 microg/kg body weight) or vehicle five times per week. Mice were killed at 8 or 15 days, and both tibias were obtained. Bone histomorphometry of the trabecular bone in the proximal tibia, development of osteogenic cells, and mRNA expression of osteogenic molecules in bone marrow cells were assessed. RESULTS AND CONCLUSIONS: At 15 days of unloading, bone volume decreased in PTH-treated mice. The increase in the bone formation rate by PTH was depressed, and the osteoclast surface was thoroughly increased. The increase in alkaline phosphatase-positive colony-forming units-fibroblastic (CFU-f) colonies induced by PTH was maintained and that of TRACP+ multinucleated cells enhanced. The PTH-induced increase in c-fos mRNA was depressed, but the increases in Osterix and RANKL mRNA were maintained. Unloading promoted the PTH-associated osteoclastogenesis and seemed to delay the progression of osteogenic differentiation in association with reduction of the PTH-dependent increase of c-fos mRNA in bone marrow cells.

Prostaglandin E2 receptor (EP4) selective agonist (ONO-4819.CD) accelerates bone repair of femoral cortex after drill-hole injury associated with local upregulation of bone turnover in mature rats.

Prostaglandin E(2) (PGE(2)) is essential for fracture healing. Systemic administration of EP4 ligands such as PGE(2) and other synthetic EP4 agonists appears to transduce anabolic signals by binding to receptor EP4. Therefore, the present study was designed to test whether administration of EP4 agonist accelerates the healing of drill-hole injury in the femoral diaphysis. After surgery, a total of 128 Wistar rats, at the age of 12 weeks, were assigned to basal control (n = 8), and three groups with respective doses of 0 (vehicle control), 10 (low-dose), and 30 (high-dose) microg/kg body weight of the agent were subcutaneously injected twice a day. Femoral specimens were obtained at 0, 5, 7, 14, 21, and 28 days. In EP4 agonist-treated groups, the total bone volume of the regenerating bone in the defect did not significantly differ, but the regenerated cortical bone volume measured by histomorphometry and cortical bone mineral content (Ct. BMC) by pQCT dose-dependently increased at 14 and 21 days compared to the control. In the high-dose group, the value of osteoclast surface significantly increased compared with that in the control at 14 days. Expression levels of osteocalcin and TRAP mRNAs in the injured tissue increased at 14 days. Expression levels of EP4, BMP-2, and RANKL mRNAs increased at 7 days in the high-dose group. The bone mineral values of the lumbar bone at 28 days, measured by DXA, did not differ in the three groups. These data indicated that systemic administration of EP4 agonist ONO-4819.CD accelerated cortical bone healing after drill-hole injury by upregulating the local turnover of the regenerating bone.