A comparison of different thicknesses of mouthguards according to the groove shape of sheets.

BACKGROUND/AIMS: Previous studies have compared the thickness of the device with and without grooves. The result was a difference in thickness of the device along the groove. The aim of this study was to assess the differences in thickness of mouthguards that result from different groove shapes of ethylene vinyl acetate sheets used to make these appliances. MATERIALS AND METHOD: Mouthguards were made using a 3-dimensional printer, and produced by softening 4 mm transparent circular sheets. Four different shapes of sheets were evaluated: normal sheets, sheets with anterior V-shaped grooves, sheets with anterior A-shaped grooves, and sheets with posterior A-shaped grooves. The groove was 3 mm deep and 5 mm wide. The thickness of the appliance was assessed with respect to the anterior incisal edge, labial surface, palatal surface, posterior cusp, buccal surface, and palatal surface. The Kruskal-Wallis test was used to analyze differences in thickness among the different groove shapes. RESULTS: No significant difference was detected between the thickness of mouthguards made using sheets with grooves and that of mouthguards made using sheets without grooves (P > .05). CONCLUSION: The presence of grooves on the sheets did not influence mouthguard thickness.

Pressure Differences from Clear Aligner Movements Assessed by Pressure Sensors.

OBJECTIVES: In this study, a clear aligner was moved at intervals of 0.25 mm and pressure variations were assessed using a sensor. METHODS: The model used for producing the clear aligner was created using a 3-dimensional printer. A clear, circular thermoplastic of 0.75 mm thickness was used for making the clear aligner using the vacuum forming method. A pressure sensor was used to assess the pressure in the device, and the variation in the sheet pressure was statistically analyzed tooth movement using the clear aligner, moving at an interval of 0.25 mm, is recommended. RESULTS: The results of pressure sensor assessment showed that the pressure of the devices with 0.25 mm and 1.00 mm movements was identical to that of the device with 0 mm movement. In other words, the pressure sensor could not distinguish the pressure of devices that moved 0.25 mm and 1.00 mm. CONCLUSIONS: This experiment demonstrated that a movement of more than 0.50 mm is needed to apply the appropriate pressures needed for orthodontics in a clear polymer sheet.

4-Phenylbutyric acid protects against lipopolysaccharide-induced bone loss by modulating autophagy in osteoclasts.

4-Phenylbutyric acid (4-PBA) has been used clinically to treat urea cycle disorders and is known to be an inhibitor of endoplasmic reticulum (ER) stress. We hypothesized that 4-PBA attenuates inflammatory bone loss by inducing autophagy, a process that is frequently accompanied by ER stress. Micro computerized tomography analysis showed that 4-PBA attenuated LPS-induced bone loss in mice. The increased area of TRAP-positive osteoclasts (OCs) and serum level of collagen type I fragments in lipopolysaccharide (LPS)-treated mice were also decreased when 4-PBA was administered, suggesting a protective role of 4-PBA in OCs. In vitro, 4-PBA significantly reduced OC area without affecting the number of OCs induced by LPS and decreased bone resorption upon LPS stimulation. LPS-induced autophagy was attenuated by 4-PBA in OCs, as demonstrated by reduced LC3II accumulation, increased p62 level, and reduction in AVO-containing cells. Silencing of autophagy-related protein 7 attenuated the effects of 4-PBA on OC size and fusion. Moreover, 4-PBA reduced nuclear factor-κB (NF-κB) DNA binding upon LPS stimulation of OCs. Inhibition of NF-κB activation diminished the inhibitory effect of 4-PBA on LPS-stimulated changes in LC3II level, OC area, and OC fusion, implying that the effects of 4-PBA on OCs are due at least in part to inhibition of NF-κB. These data demonstrate that 4-PBA attenuates LPS-induced bone loss by reducing autophagy in OCs. Our data highlight the therapeutic potential of 4-PBA for ameliorating inflammatory bone loss.

Lipopolysaccharide (LPS)-Induced Autophagy Is Responsible for Enhanced Osteoclastogenesis.

We hypothesized that inflammation affects number and activity of osteoclasts (OCs) via enhancing autophagy. Lipopolysaccharide (LPS) induced autophagy, osteoclastogenesis, and cytoplasmic reactive oxygen species (ROS) in bone marrow-derived macrophages that were pre-stimulated with receptor activator of nuclear factor-κB ligand. An autophagy inhibitor, 3-methyladenine (3-MA) decreased LPS-induced OC formation and bone resorption, indicating that autophagy is responsible for increasing number and activity of OCs upon LPS stimulus. Knockdown of autophagy-related protein 7 attenuated the effect of LPS on OC-specific genes, supporting a role of LPS as an autophagy inducer in OC. Removal of ROS decreased LPS-induced OC formation as well as autophagy. However, 3-MA did not affect LPS-induced ROS levels, suggesting that ROS act upstream of phosphatidylinositol-4,5-bisphosphate 3-kinase in LPS-induced autophagy. Our results suggest the possible use of autophagy inhibitors targeting OCs to reduce inflammatory bone loss.

Effects of dialkoxylphenyl compounds with oxime group on macrophage function and the proliferation of lymphocytes.

Dialkoxyphenyl compounds have been reported to possess anti-inflammatory activity through inhibition of phosphodieseterase (PDE) type IV. In this study, a series of derivatives of dialkoxyphenyl compounds with an oxime group, which is generally known to be one of the biologically active functional groups, were prepared and evaluated for their ability to inhibit the production of inflammatory mediators in activated macrophages and the proliferation of lymphocytes. The structure-activity relationship (SAR) study with 12 compounds on tumour necrosis factor (TNF)-alpha inhibition, analysed by the oxime geometry and different size of spacers between the oxime and phenyl group, indicated that there might be at least three possible hydrogen bonding sites in the inhibitor binding pocket of PDE IV. Of them, compound 6 clearly displayed the highest inhibitory effect on in-vitro TNF-alpha production from lipopolysaccharide (LPS)-stimulated RAW264.7 cells. Compound 6 also suppressed in-vivo TNF-alpha release from LPS-primed mice, a level comparable with that of the standard PDE IV inhibitor, rolipram. In addition, oxime compounds also significantly inhibited both nitric oxide production from activated RAW264.7 cells and T lymphocyte proliferation elicited by concanavalin A but not IL-2. The data suggest that the oxime group may act as a functional group, capable of interacting with the inhibitor-binding pocket of target PDE IV. Therefore, it is conceivable that compound 6 may have the potential either to be developed as a new anti-inflammatory drug or to be used to develop more potent analogues.

Influence of dentin porcelain thickness on layered all-ceramic restoration color.

OBJECTIVES: Final aesthetic performance of all-ceramic restorations is influenced by the thickness ratio of core and porcelain ceramics. This study aimed to identify and quantify the effect of increased dentin porcelain thickness on the color and color coordinates of all-ceramic specimens. METHODS: Lava and IPS e.max Press all-ceramic systems were investigated. A1, A2 and A3.5 shades of layered specimens were made with 2-mm ceramic cores and 0-2mm bevelled dentin porcelain. Color was measured at 0.05mm dentin porcelain thickness intervals with a spectroradiometer. The effect of ceramic brand, shade and dentin porcelain thickness on color change was analyzed by 3-way ANOVA. RESULTS: Color changes of layered ceramics varied by ceramic brand, shade and dentin porcelain thickness. For most ceramics, CIE a* and b* values gradually increased as the thickness of the dentin porcelain increased. Conversely, such increases in dentin porcelain thickness were correlated with decreasing CIE L* values. When compared with the IPS e.max Press ceramics, Lava ceramics showed smaller color changes in response to increases in dentin porcelain thickness. CONCLUSIONS: The final appearance of ceramic restorations can be manipulated by varying the dentin porcelain thickness; however, the color of the layered ceramics varied by ceramic brand, shade and dentin porcelain thickness.