The purpose of the study was to evaluate the effect of autoclaving one-step polishing systems on ... more The purpose of the study was to evaluate the effect of autoclaving one-step polishing systems on the surface roughness of a nanoparticle resin composite. Sixty disk-shaped specimens were fabricated (ø 12 mm and 2.5 mm height) with Tetric N-Ceram (IvoclarVivadent). Thirty discs were polished with brushes (Astrobrush, IvoclarVivadent)and the other 30 discs with rubber tips (Optrapol, Ivoclar Vivadent). The specimens were divided into 6 groups (n = 10), according to the association between polishing system and number of autoclave cycles: G1, Astrobrush used for first time and without autoclave (control); G2, Astrobrush used after the 10th autoclave cycle; G3, Astrobrush used after the 20th autoclave cycle; G4, Optrapol used for first time and without autoclave (control); G5, Optrapol used after the 10th autoclave cycle; G6, Optrapol used after the 20th autoclave cycle. The surface roughness (R a ) of each specimen and the data was used for analysis of variance (ANOVA). There was no significantly statistical difference between groups for both of the one-step polishing systems (p > 0.05). The Astrobrush system presented R a values statistically lower than Optrapol system (p < 0.05). Twenty cycles of autoclaving, did not affect the surface roughness produced by polishing systems on the resin composite evaluated.
The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on t... more The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on the fatigue resistance of molars restored with CAD/CAM ceramic inlays. Forty human third molars were selected and divided into 4 groups, according to the remaining surrounding wall thickness chosen for inlay preparation (n=10): G1, 2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were made from feldspathic ceramic blocks by a CAD/CAM system, and cemented adhesively. After 1 week stored in distilled water at 37 °C, the specimens were subjected to fatigue testing under the following protocol: 5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of 400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimens were cycled until failure or completion of 185,000 cycles. The survival rate of the groups was compared using the Kaplan-Meier survival curves (p&amp;amp;amp;amp;amp;amp;gt;0.05). All specimens withstood the fatigue protocol (185,000 cycles), representing a 100% survival rate. The Kaplan-Meier survival curves showed no difference between groups. It can be concluded that the remaining tooth wall thickness did not influence the fatigue resistance of molars restored with CAD/CAM ceramic inlays.
Spot14 is a putative transcriptional regulator for genes involved in fatty acid synthesis. The Sp... more Spot14 is a putative transcriptional regulator for genes involved in fatty acid synthesis. The Spot14 gene is activated in response to lipogenic stimuli such as dietary carbohydrate and is also under circadian regulation. The authors investigated factors responsible for daily oscillation of Spot14 expression. If mice were kept under a 12-h light/12-h dark cycle with ad libitum feeding, Spot14 mRNA levels in the liver reached a peak at an early dark period when mice, as nocturnal animals, start feeding. Under fasting, while Spot14 mRNA levels were generally decreased, the rhythmicity was still maintained, suggesting contribution of both nutritional elements and circadian clock factors on robust rhythmicity of Spot14 expression. Effects of circadian clock factors were confirmed by the observations that the circadian rhythm of Spot14 expression was seen also under the constant darkness and that the rhythmicity was lost in Clock mutant mice. When mice were housed in short-photoperiod (6-h light/18-h dark) and long-photoperiod (18-h light/6-h dark) cycles, rhythms of Spot14 mRNA levels were phase advanced and phase delayed, respectively, being concordant with the notion that Spot14 expression is under the control of the light-entrainable oscillator. As for nutritional mediators, in the liver of db/db mice exhibiting hyperinsulinemia-accompanied hyperglycemia, Spot14 mRNA levels were constantly high without apparent rhythmicity, consistent with previous observations for strong activation of the Spot14 gene by glucose and insulin. Restricted feeding during the 4-h mid-light period caused a phase advance of the Spot14 expression rhythm. On the other hand, restricted feeding during the 4-h mid-dark period led to damping of the rhythmicity, apparently resulting from the separation of phases between effects of the light/dark cycle and feeding on Spot14 expression. Thus, the daily rhythm of Spot14 expression in the liver is under the control of the light-entrainable oscillator, food-entrainable oscillator, and food-derived nutrients, in a separate or cooperative manner.
Background: MKK7 is a kinase involved in the cellular stress response. Results: MKK7 regulates ci... more Background: MKK7 is a kinase involved in the cellular stress response. Results: MKK7 regulates circadian gene expression and the stability of an essential circadian component in unstressed mammalian cells. Conclusion: MKK7 functions as a circadian clock regulator. Significance: Our identification of role of MKK7 in the circadian clock provides insight into the importance of stress-responsive molecules in the maintenance of cellular homeostasis.
d e n t a l m a t e r i a l s 2 7 S ( 2 0 1 1 ) e1-e84 e73 consecutive sampling lengths and Rz). ... more d e n t a l m a t e r i a l s 2 7 S ( 2 0 1 1 ) e1-e84 e73 consecutive sampling lengths and Rz). Two-way ANOVA and a Tukey test (p<0.05) were applied. SEM analysis was performed.
Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydro... more Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and catabolic enzymes such as cytochrome P-450, family 7, subfamily A, and polypeptide 1 (CYP7A1). Since a circadian clock controls the gene expression of these enzymes, these genes exhibit circadian rhythm in the liver. In this study, we examined the relationship between a diet containing CH and/or cholic acid (CA) and the circadian regulation of Hmgcr, low-density lipoprotein receptor (Ldlr), and Cyp7a1 gene expression in the mouse liver. A 4-wk CA diet lowered and eventually abolished the circadian expression of these genes. Not only clock genes such as period homolog 2 (Drosophila) (Per2) and brain and muscle arnt-like protein-1 (Bmal1) but also clock-controlled genes such as Hmgcr, Ldlr, and Cyp7a1 showed a reduced and arrhythmic expression pattern in the liver of Clock mutant mice. The reduced gene expression of Cyp7a1 in mice fed a diet containing CA or CH + CA was remarkable in the liver of Clock mutants compared with wild-type mice, and high liver CH accumulation was apparent in Clock mutant mice. In contrast, a CH diet without CA only elevated Cyp7a1 expression in both wild-type and Clock mutant mice. The present findings indicate that normal circadian clock function is important for the regulation of CH homeostasis in the mouse liver, especially in conjunction with a diet containing high CH and CA.
Objective: To evaluate, in vitro, the effect of acid etching time and surface preparation on the ... more Objective: To evaluate, in vitro, the effect of acid etching time and surface preparation on the microtensile bond strength (MTBS) of a one-bottle two step total etch adhesive system to enamel. Method: Twenty human third molars were selected and mesio-distally sectioned for obtaining forty enamel surfaces. With half of them, the enamel surface was grounded using a high-speed diamond bur (P) under water irrigation. With the other half, the surface was not prepared (NP). A 35% phosphoric acid (3M ESPE) was applied for either 15 or 30 seconds, in both groups. After rinsing the acid etching, the enamel surface was air dried and the adhesive (Adper Single Bond 2, 3M ESPE) was applied, according to manufactures instructions. The adhesive was gently air dried and light cured. A hybrid resin composite (Filtek Z350, 3M ESPE) was applied in 3 increments of 2.0mm and light cured for 20 seconds each with a final polymerization of 60 seconds. After 24 hours in water, the specimens were sectioned...
The purpose of the study was to evaluate the effect of autoclaving one-step polishing systems on ... more The purpose of the study was to evaluate the effect of autoclaving one-step polishing systems on the surface roughness of a nanoparticle resin composite. Sixty disk-shaped specimens were fabricated (ø 12 mm and 2.5 mm height) with Tetric N-Ceram (IvoclarVivadent). Thirty discs were polished with brushes (Astrobrush, IvoclarVivadent)and the other 30 discs with rubber tips (Optrapol, Ivoclar Vivadent). The specimens were divided into 6 groups (n = 10), according to the association between polishing system and number of autoclave cycles: G1, Astrobrush used for first time and without autoclave (control); G2, Astrobrush used after the 10th autoclave cycle; G3, Astrobrush used after the 20th autoclave cycle; G4, Optrapol used for first time and without autoclave (control); G5, Optrapol used after the 10th autoclave cycle; G6, Optrapol used after the 20th autoclave cycle. The surface roughness (R a ) of each specimen and the data was used for analysis of variance (ANOVA). There was no significantly statistical difference between groups for both of the one-step polishing systems (p > 0.05). The Astrobrush system presented R a values statistically lower than Optrapol system (p < 0.05). Twenty cycles of autoclaving, did not affect the surface roughness produced by polishing systems on the resin composite evaluated.
The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on t... more The purpose of this study was to evaluate the influence of buccal and lingual wall thickness on the fatigue resistance of molars restored with CAD/CAM ceramic inlays. Forty human third molars were selected and divided into 4 groups, according to the remaining surrounding wall thickness chosen for inlay preparation (n=10): G1, 2.0 mm; G2, 1.5 mm; G3, 1.0 mm; G4, 0.5 mm. All inlays were made from feldspathic ceramic blocks by a CAD/CAM system, and cemented adhesively. After 1 week stored in distilled water at 37 °C, the specimens were subjected to fatigue testing under the following protocol: 5Hz; pre-load of 200 N for 5,000 cycles, followed by increasing loads of 400, 600, 800, 1000, 1200 and 1400 N for 30,000 cycles each. The specimens were cycled until failure or completion of 185,000 cycles. The survival rate of the groups was compared using the Kaplan-Meier survival curves (p&amp;amp;amp;amp;amp;amp;gt;0.05). All specimens withstood the fatigue protocol (185,000 cycles), representing a 100% survival rate. The Kaplan-Meier survival curves showed no difference between groups. It can be concluded that the remaining tooth wall thickness did not influence the fatigue resistance of molars restored with CAD/CAM ceramic inlays.
Spot14 is a putative transcriptional regulator for genes involved in fatty acid synthesis. The Sp... more Spot14 is a putative transcriptional regulator for genes involved in fatty acid synthesis. The Spot14 gene is activated in response to lipogenic stimuli such as dietary carbohydrate and is also under circadian regulation. The authors investigated factors responsible for daily oscillation of Spot14 expression. If mice were kept under a 12-h light/12-h dark cycle with ad libitum feeding, Spot14 mRNA levels in the liver reached a peak at an early dark period when mice, as nocturnal animals, start feeding. Under fasting, while Spot14 mRNA levels were generally decreased, the rhythmicity was still maintained, suggesting contribution of both nutritional elements and circadian clock factors on robust rhythmicity of Spot14 expression. Effects of circadian clock factors were confirmed by the observations that the circadian rhythm of Spot14 expression was seen also under the constant darkness and that the rhythmicity was lost in Clock mutant mice. When mice were housed in short-photoperiod (6-h light/18-h dark) and long-photoperiod (18-h light/6-h dark) cycles, rhythms of Spot14 mRNA levels were phase advanced and phase delayed, respectively, being concordant with the notion that Spot14 expression is under the control of the light-entrainable oscillator. As for nutritional mediators, in the liver of db/db mice exhibiting hyperinsulinemia-accompanied hyperglycemia, Spot14 mRNA levels were constantly high without apparent rhythmicity, consistent with previous observations for strong activation of the Spot14 gene by glucose and insulin. Restricted feeding during the 4-h mid-light period caused a phase advance of the Spot14 expression rhythm. On the other hand, restricted feeding during the 4-h mid-dark period led to damping of the rhythmicity, apparently resulting from the separation of phases between effects of the light/dark cycle and feeding on Spot14 expression. Thus, the daily rhythm of Spot14 expression in the liver is under the control of the light-entrainable oscillator, food-entrainable oscillator, and food-derived nutrients, in a separate or cooperative manner.
Background: MKK7 is a kinase involved in the cellular stress response. Results: MKK7 regulates ci... more Background: MKK7 is a kinase involved in the cellular stress response. Results: MKK7 regulates circadian gene expression and the stability of an essential circadian component in unstressed mammalian cells. Conclusion: MKK7 functions as a circadian clock regulator. Significance: Our identification of role of MKK7 in the circadian clock provides insight into the importance of stress-responsive molecules in the maintenance of cellular homeostasis.
d e n t a l m a t e r i a l s 2 7 S ( 2 0 1 1 ) e1-e84 e73 consecutive sampling lengths and Rz). ... more d e n t a l m a t e r i a l s 2 7 S ( 2 0 1 1 ) e1-e84 e73 consecutive sampling lengths and Rz). Two-way ANOVA and a Tukey test (p<0.05) were applied. SEM analysis was performed.
Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydro... more Cholesterol (CH) homeostasis in the liver is regulated by enzymes of CH synthesis such as 3-hydroxy-3-methylglutaryl coenzyme A reductase (HMGCR) and catabolic enzymes such as cytochrome P-450, family 7, subfamily A, and polypeptide 1 (CYP7A1). Since a circadian clock controls the gene expression of these enzymes, these genes exhibit circadian rhythm in the liver. In this study, we examined the relationship between a diet containing CH and/or cholic acid (CA) and the circadian regulation of Hmgcr, low-density lipoprotein receptor (Ldlr), and Cyp7a1 gene expression in the mouse liver. A 4-wk CA diet lowered and eventually abolished the circadian expression of these genes. Not only clock genes such as period homolog 2 (Drosophila) (Per2) and brain and muscle arnt-like protein-1 (Bmal1) but also clock-controlled genes such as Hmgcr, Ldlr, and Cyp7a1 showed a reduced and arrhythmic expression pattern in the liver of Clock mutant mice. The reduced gene expression of Cyp7a1 in mice fed a diet containing CA or CH + CA was remarkable in the liver of Clock mutants compared with wild-type mice, and high liver CH accumulation was apparent in Clock mutant mice. In contrast, a CH diet without CA only elevated Cyp7a1 expression in both wild-type and Clock mutant mice. The present findings indicate that normal circadian clock function is important for the regulation of CH homeostasis in the mouse liver, especially in conjunction with a diet containing high CH and CA.
Objective: To evaluate, in vitro, the effect of acid etching time and surface preparation on the ... more Objective: To evaluate, in vitro, the effect of acid etching time and surface preparation on the microtensile bond strength (MTBS) of a one-bottle two step total etch adhesive system to enamel. Method: Twenty human third molars were selected and mesio-distally sectioned for obtaining forty enamel surfaces. With half of them, the enamel surface was grounded using a high-speed diamond bur (P) under water irrigation. With the other half, the surface was not prepared (NP). A 35% phosphoric acid (3M ESPE) was applied for either 15 or 30 seconds, in both groups. After rinsing the acid etching, the enamel surface was air dried and the adhesive (Adper Single Bond 2, 3M ESPE) was applied, according to manufactures instructions. The adhesive was gently air dried and light cured. A hybrid resin composite (Filtek Z350, 3M ESPE) was applied in 3 increments of 2.0mm and light cured for 20 seconds each with a final polymerization of 60 seconds. After 24 hours in water, the specimens were sectioned...
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Papers by S. Shibata