The purpose of this study was to investigate the effect of adding a protective coating on the microhardness and wear resistance of glass ionomer cements (GICs).Specimens were prepared from GIC and resin-modified GIC (RMGI), and divided into 3 groups based on surface protection: (1) no coating (NC), (2) Equia coat coating (EC), and (3) un-filled adhesive coating (AD). All specimens were then placed in distilled water for 24 h. Surface hardness (n = 10) was evaluated on a Vickers hardness testing machine. Wear resistance (n = 10) was evaluated after subjecting the specimen to thermocycling for 10,000 cycles using a chewing simulator. Data were analyzed using a one-way ANOVA and the Kruskal-Wallis test.Surface hardness was highest in the NC groups, followed by the EC and AD groups. The wear depth of GI + NC was significantly higher than that of all RMGI groups. EC did not significantly lower the wear depth compared to AD.Based on these results, it was concluded that although EC does not increase the surface microhardness of GIC, it can increase the wear resistance.
Adhesives ; Glass Ionomer Cements ; Hardness ; Hardness Tests ; Mastication ; Water

Objective of this study was to compare the color stability, mechanical and chemical properties of three different types of temporary crown resins. Commercially available powder-liquid (Group PL), light-cured (Group LC) and auto-mix syringe (Group AM) types' temporary crown resins were used as experimental groups for each of the evaluation. All the test groups were evaluated after 1 day and 7 days of immersion in various staining solutions. The colors of all groups before and after storage in the staining solutions were measured by a spectrophotometer based on CIE Lab system, and the color differences (ΔE(*)) thereby calculated. Micro hardness test was performed before water storage and aging after 7 days at 37 ℃. In addition, flexural strength, water sorption and solubility tests were performed according to international standard, ISO 10477. All experimental groups showed significant color change in staining solutions when compared to those stored in the control solution (distilled water) (p<0.05). Group PL showed the least color change among the three groups followed by Group AM (p<0.05). This tendency was observed after 7 days of immersion. In terms of the micro hardness test, Group PL showed the highest value among the three groups followed by Group AM (p<0.05). Additionally, the flexural strength decreased in the following order: AM > PL > LC (p<0.05). Water sorption and solubility increased in the following order: AM < PL < LC (p<0.05). The results of this study would provide useful information when choosing temporary crown resin types in various clinical situations.
Aging ; Crowns ; Hardness Tests ; Immersion ; Solubility ; Syringes ; Water

OBJECTIVES: The purpose of this study was to investigate the effects of dry syrups on bovine tooth surfaces. METHODS: Each specimen of the extracted bovine teeth enamel was treated with two types of dry syrup (experimental group), mineral water (negative control group), and liquid syrup (positive control group) (n=12 per group). The specimens were immersed for 1, 5, and 10 minutes and subsequently analyzed for surface microhardness changes using a Vickers hardness tester. RESULTS: The surface microhardness of sound enamel decreased as the immersion time increased. In addition, the microhardness difference (ΔVHN) among the groups after immersion for 10 minutes in both liquid syrup and two types of dry syrup was higher than that after immersion in mineral water (P<0.05). There were significant differences between the liquid syrup group and the two dry syrup groups (P<0.05). However, there was no significant difference between the two groups of dry syrup (P>0.05). CONCLUSIONS: These results imply the erosive potential of dry syrup on tooth surfaces. The longer the contact time with teeth, greater is the risk of dental erosion. Therefore, it is recommended that the mouth be rinsed with water after drinking the syrup.
Dental Enamel ; Drinking ; Hardness Tests ; Immersion ; Mineral Waters ; Mouth ; Tooth ; Water

PURPOSE: The aim of this study was to evaluate the polymerization ability of resin-based materials used for teeth splinting according to the thickness of cure. MATERIALS AND METHODS: For this study, the Light-Fix and G-FIX developed for resinous splinting materials and the G-aenial Universal Flo, the high-flowable composite resin available as restorative and splinting material, were used. Ten specimens of the thickness of 2, 3, 4 and 5 mm and 5 mm in diameter for each composite resin (total 120) were prepared. The microhardness of top and bottom surfaces for each specimen was measured by the Vickers hardness testing machine. The polymerization ability of the composite resin for each thickness was statistically analyzed using independent T-test at a 0.05 level of significance. RESULTS: There was no difference of polymerization ability regardless of the thickness in the Light-Fix and G-FIX. The G-aenial Universal Flo showed significantly low polymerization ability from the thickness of the 3 mm (P < 0.05). CONCLUSION: The Light-Fix and G-FIX, which are resin-based materials used for teeth splinting, are expected to be suitable for light curing up to 5 mm in thickness.
Hardness Tests ; Polymerization ; Polymers ; Splints ; Tooth Mobility ; Tooth

To improve the oral health status of Korean people, it is necessary to encourage proper oral hygiene management habits, such as toothbrushing, through appropriate health promotion techniques. Therefore, the purpose of this study was to evaluate the removal of plaque and tooth abrasion using ultra-soft (filament 0.11~0.12 mm) and soft toothbrushes for toothbrushing. The plaque removal was performed using a dentiform and Arti-spray, and the Patient Hygiene Performance (PHP) index was calculated as the sum total score divided by the total number of surfaces. In the abrasivity experiment, according to the number of brushings, a micro Vickers hardness tester was used, and a sample in the range of 280~380 Vickers hardness number was selected. The number of toothbrushing stroke were 1,800 (2 months), 5,400 (6 months), 10,800 (12 months), and 21,600 (24 months). The tooth abrasion was measured using a scanning electron microscope. Statistical analysis was performed using IBM SPSS Statistics 22.0 and a p-value < 0.05 was considered significant. According to the results, there was no statistically significant difference in the degree of plaque removal between ultra-soft and soft toothbrushes. The difference in tooth abrasion between before and after toothbrushing was found to be greater with the soft toothbrushes than with the ultra-soft toothbrushes. Therefore, the ultra-soft toothbrush not only lowers tooth damage by reducing tooth abrasion, but also shows a similar ability to remove plaque as soft toothbrushes.
Dental Plaque ; Hardness ; Hardness Tests ; Health Promotion ; Humans ; Hygiene ; Oral Health ; Oral Hygiene ; Stroke ; Tooth Abrasion* ; Tooth* ; Toothbrushing

OBJECTIVES: The purpose of this study was to evaluate the erosive potential of tea beverages containing citric acid on tooth surfaces. METHODS: Specimens of extracted bovine teeth enamel were embedded in resin and polished. The specimens were subjected to one of three treatments (n=10 per treatment group): mineral water, brewed black tea, or black tea beverage. Tooth specimens were exposed to the treatment for 30 minutes and then analyzed using Vickers surface hardness testing and scanning electron microscopy. RESULTS: After 30 minutes of treatment, there were statistically significant differences between the hardness of the enamel pre- and post-treatment in both, the brewed black tea and black tea beverage groups (P<0.05). The differences in microhardness (ΔVHN) were ―71.49±14.99, ―9.05±10.25, and ―2.43±15.44 in the black tea beverage, brewed black tea, and mineral water groups, respectively. In the difference of microhardness (ΔVHN) between groups, the black tea beverage group showed significantly greater changes than the brewed black tea and mineral water groups (P<0.05). However, there was no significant difference between the brewed black tea group and the mineral water group (P>0.05).On observation using a scanning electron microscope, the tooth surfaces exposed to the black tea beverage containing citric acid were rougher than the tooth surfaces in the other two groups. CONCLUSIONS: This study demonstrates the erosive potential of citric acid-containing tea beverages on tooth surfaces. Thus, there is need to caution people regularly consuming tea beverages containing citric acid, regarding the possibility of tooth surface erosion.
Beverages* ; Citric Acid* ; Dental Enamel ; Hardness ; Hardness Tests ; Microscopy, Electron, Scanning ; Mineral Waters ; Tea* ; Tooth*

OBJECTIVES: The purpose of this study was to evaluate the effect of a dentifrice containing 1,500 ppm F (NaF) and 2% bamboo salt on dental erosion caused by ingestion of acidic beverages. METHODS: Specimens of extracted bovine teeth enamel were embedded in a resin and polished. Experimental specimens were subjected to one of the six treatments (n=10 per treatment group): the experimental group consisted of 1,500 ppm F (NaF)+2% bamboo salt; 1,500 ppm F (NaF); 1,000 ppm F (NaF)+2% bamboo salt; 1,000 ppm F (NaF); free fluoride+2% bamboo salt; and free fluoride. The specimens were exposed to the experimental dentifrice, an acidic beverage, and artificial saliva. The treated specimens were analyzed using a Vickers surface hardness test and scanning electron microscopy (SEM). Surface hardness and SEM were compared before and after the chemical pH cycling sequences for 12 days. RESULTS: Group 1 (1,500 ppm F+2% bamboo salt) showed the highest surface hardness, followed by group 2 (1,500 ppm F), group 3 (1,000 ppm F+2% bamboo salt), group 4 (1,000 ppm F), group 5 (free fluoride+2% bamboo salt), and group 6 (free fluoride), in that order. Upon observing the surface by SEM, when bamboo salt was used and when the NaF concentration was higher, the enamel was denser and the surface was more highly remineralized. CONCLUSIONS: The use of a higher concentration of NaF and bamboo salt resulted in a higher preventive effect on tooth erosive potential. The addition of bamboo salt to dentifrice containing a high concentration of NaF can contribute to preventing dental erosion.
Beverages ; Dental Enamel ; Dentifrices* ; Eating ; Fluorides ; Hardness ; Hardness Tests ; Hydrogen-Ion Concentration ; Microscopy, Electron, Scanning ; Saliva, Artificial ; Tooth

PURPOSE: The purpose of the present study was to investigate whether hardness of liver surface correlated with degree of liver fibrosis, and its association with posthepatectomy liver failure (PHLF). METHODS: A shore durometer was used to measure hepatic hardness in 41 patients with hepatocellular carcinoma (HCC) and in 10 patients with normal liver. We investigated how hepatic hardness correlates with various values indicating the degree of liver fibrosis, and how it correlates with PHLF. RESULTS: In the normal liver group, the surface shore units (SU) was 15.06 ± 2.64. In the HCC group, there was a correlation between surface SU and preoperative results indicating liver fibrosis. Among patients with PHLF after resecting over 3 segments, the surface SU of patients with grade A PHLF was 21.85 ± 5.63, and the surface SU of patients with grade C PHLF was 35.75 ± 9.26. In patients with PHLF after resecting 2 or less segments, the surface SU of patients with PHLF grade A was 20.95 ± 5.18, and the surface SU of patients with PHLF grade B was 31.60 ± 5.57. In predicting PHLF, surface SU was more effective than preoperative platelet count, spleen volume, or liver fibrosis index. CONCLUSION: Hepatic hardness measured by the shore durometer was correlated with the degree of liver fibrosis. Liver surface SU was a more effective parameter for predicting PHLF, as compared to other indicators evaluated before hepatectomy. The decision to perform major hepatectomy should be reconsidered in cases with a liver surface SU of >30.
Carcinoma, Hepatocellular ; Hardness ; Hardness Tests ; Hepatectomy ; Humans ; Liver Cirrhosis* ; Liver Failure ; Liver Function Tests ; Liver* ; Platelet Count ; Spleen

PURPOSE: The purpose of the present study was to investigate whether hardness of liver surface correlated with degree of liver fibrosis, and its association with posthepatectomy liver failure (PHLF). METHODS: A shore durometer was used to measure hepatic hardness in 41 patients with hepatocellular carcinoma (HCC) and in 10 patients with normal liver. We investigated how hepatic hardness correlates with various values indicating the degree of liver fibrosis, and how it correlates with PHLF. RESULTS: In the normal liver group, the surface shore units (SU) was 15.06 ± 2.64. In the HCC group, there was a correlation between surface SU and preoperative results indicating liver fibrosis. Among patients with PHLF after resecting over 3 segments, the surface SU of patients with grade A PHLF was 21.85 ± 5.63, and the surface SU of patients with grade C PHLF was 35.75 ± 9.26. In patients with PHLF after resecting 2 or less segments, the surface SU of patients with PHLF grade A was 20.95 ± 5.18, and the surface SU of patients with PHLF grade B was 31.60 ± 5.57. In predicting PHLF, surface SU was more effective than preoperative platelet count, spleen volume, or liver fibrosis index. CONCLUSION: Hepatic hardness measured by the shore durometer was correlated with the degree of liver fibrosis. Liver surface SU was a more effective parameter for predicting PHLF, as compared to other indicators evaluated before hepatectomy. The decision to perform major hepatectomy should be reconsidered in cases with a liver surface SU of >30.
Carcinoma, Hepatocellular ; Hardness ; Hardness Tests ; Hepatectomy ; Humans ; Liver Cirrhosis* ; Liver Failure ; Liver Function Tests ; Liver* ; Platelet Count ; Spleen

OBJECTIVES: We compared the effects of a 1,500 ppm fluoride-containing toothpaste and a 1,000 ppm fluoride-containing toothpaste, which were revised up to the recent revision, and evaluated their effects on the tooth surface after adding bamboo salt to the preparations. METHODS: Experimental early artificial caries specimens were subjected to one of four treatments (n=12 per treatment group): 1,500 ppm NaF, 2% bamboo salt+1,000 ppm NaF, 1,000 ppm NaF, and control treatment. The specimens were exposed to the experimental toothpaste, artificial saliva, and demineralized solution. The treated specimens were analyzed using Vickers surface hardness testing, scanning electron microscopy, and atomic force microscopy. RESULTS: The toothpaste with a high fluoride concentration (1,500 ppm NaF) showed more remineralization than did the toothpaste with a low fluoride concentration (1,000 ppm NaF). The 2% bamboo salt+1,000 ppm NaF group showed remineralization similar to the 1,500 ppm NaF group and higher surface microhardness than the 1,000 ppm NaF group. CONCLUSIONS: Toothpastes containing 1,500 ppm NaF have a higher preventive effect against dental caries than do toothpastes containing 1,000 ppm NaF. The addition of bamboo salt to fluoride-containing dentifrices improves their effectiveness in preventing dental caries.
Dental Caries ; Dental Enamel* ; Dentifrices ; Fluorides ; Hardness Tests ; Microscopy, Atomic Force ; Microscopy, Electron, Scanning ; Saliva, Artificial ; Tooth ; Toothpastes*