PURPOSE The accuracy of denture bases was compared among injection molding, milling, and rapid prototyping (RP) fabricating method. MATERIALS AND METHODS The maxillary edentulous master cast was fabricated and round shaped four notches were formed. The cast was duplicated to ten casts and scanned. In the injection molding method, designed denture bases were milled from a wax block and fabricated using SR Ivocap injection system. Denture bases were milled from a pre-polymerized block in the milling method. In the RP method, denture bases were printed and post-cured. The intaglio surface of the base was scanned and surface matching software was used to measure inaccuracy. Measurements were performed between four notches and two points in the mid-palatal suture to evaluate inaccuracy. The palatine rugae resolution was evaluated. One-way analysis of variance was used for statistical analysis at α=.05. RESULTS No statistically significant differences in distances among four notches ( P >.05). The accuracy of the injection molding method was lower than those of the other methods in two points of the mid-palatal suture significantly ( P <.05). The degree of palatine rugae resolution was significantly higher in the injection molding method than that in other methods ( P <.05). CONCLUSION The overall accuracy of the denture base is higher in milling and RP method than the injection molding method. The degree of fine reproducibility is higher in the injection molding method than the milling or RP method.

No abstract

Melatonin's effect on hepatic differentiation of stem cells remains unclear. The aim of this study was to investigate the action of melatonin on hepatic differentiation as well as its related signaling pathways of human dental pulp stem cells (hDPSCs) and to examine the therapeutic effects of a combination of melatonin and hDPSC transplantation on carbon tetrachloride (CCl4 )-induced liver fibrosis in mice. In vitro hepatic differentiation was assessed by periodic acid-Schiff (PAS) staining and mRNA expression for hepatocyte markers. Liver fibrosis model was established by injecting 0.5 mL/kg CCl4 followed by treatment with melatonin (5 mg/kg, twice a week) and hDPSCs. In vivo therapeutic effects were evaluated by histopathology and by means of liver function tests including measurement of alanine transaminase (ALT), aspartate transaminase (AST), and ammonia levels. Melatonin promoted hepatic differentiation based on mRNA expression of differentiation markers and PAS-stained glycogen-laden cells. In addition, melatonin increased bone morphogenic protein (BMP)-2 expression and Smad1/5/8 phosphorylation, which was blocked by the BMP antagonist noggin. Furthermore, melatonin activated p38, extracellular signal-regulated kinase (ERK), and nuclear factor-κB (NF-κB) in hDPSCs. Melatonin-induced hepatic differentiation was attenuated by inhibitors of BMP, p38, ERK, and NF-κB. Compared to treatment of CCl4 -injured mice with either melatonin or hDPSC transplantation alone, the combination of melatonin and hDPSC significantly suppressed liver fibrosis and restored ALT, AST, and ammonia levels. For the first time, this study demonstrates that melatonin promotes hepatic differentiation of hDPSCs by modulating the BMP, p38, ERK, and NF-κB pathway. Combined treatment of grafted hDPSCs and melatonin could be a viable approach for the treatment of liver cirrhosis.

These data indicate, for the first time, that nontoxic DFO promotes osteoblastic differentiation of hPDLCs via modulation of the Nrf2-mediated antioxidant pathway.

The purpose of this study was to determine the effect of stabilization splints and mouthguards on the athletic ability of professional golfers. For this study, eight professional golfers with a mean age of 20.5 were selected. These participants performed four trials of 10 driver swings and 10 putts with or without a stabilization splint (control group) or mouthguard. For the 4th trial, the splints were adjusted using a simple blind test so that the participants were unaware of the unilateral molar contact. The drive distance, club head speed, initial ball speed, and putting accuracy were compared and analyzed before and after the application of equal bilateral molar occlusion. When the bilateral molar occlusion was applied using a mouthguard or stabilization splint, the club head speed and driving distance in the presence of the oral appliances were significantly increased compared with those without the presence of either appliance (P < 0.05). Alternatively, the initial ball speed and putting accuracy in the presence of these appliances were increased compared with those without the presence of an appliance; however, this effect was not statistically significant. When the mouthguards or stabilization splints were adjusted to result in unilateral molar occlusion, the club head speed and driving distance in the presence of the appliances were significantly decreased compared with those that were obtained without these appliances (P < 0.05). The initial ball speed and the putting accuracy were not affected by the use of the appliances. No difference was observed in the effectiveness of the stabilization splint and mouthguard when bilateral molar occlusion was performed. The occlusion stability that results from stabilization splints and mouthguards is thought to increase the club head speed and driving distance in professional golf players.

With precise control of CAD/CAM abutments, good screw joint stability can be achieved.

Within the limitations of this laboratory study, the following results were obtained: the results showed that increasing the thickness of the mouthguard improved its shock absorption ability.

Within the limitations of this study, the following results were obtained: the activities performed during rugby practice involved relatively small indirect head acceleration and masseter and sternocleidomastoid muscle activities. After the young male rugby players were instructed to clench their masseter muscles, a marked decrease in head acceleration was observed.