• Geomechanics and Engineering
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• v.4 no.2
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• pp.135-150
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• 2012

This paper presents the study of the effect of microorganism Bacillus pasteurii on the properties such as Atterbergs' limit and unconfined compressive strength of cohesive soils. The results of this study reveal that the liquid limit and plasticity index for all clay soils decreased and the unconfined compressive strength increased. Decrease in plasticity index is very high for Kuttanad clay followed by bentonite and laterite. The unconfined compressive strength increased for all the soils. The increase was high for Kuttanad soil and low for laterite soil. After 24 h of treatment the improvement in the soil properties is comparatively less. Besides the specific bacteria selected Bacillus pasteurii, other microorganisms may also be taking part in calcite precipitation thereby causing soil cementation. But the naturally present microorganisms alone cannot work on the calcite precipitation.

• The Journal of Advanced Prosthodontics
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• v.9 no.2
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• pp.85-92
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• 2017

PURPOSE. The aim of this study was to evaluate the effect of tooth surface pre-treatment steps on shear bond strength, which is essential for understanding the adhesive cementation process. MATERIALS AND METHODS. Shear bond strengths of different cements with various tooth surface treatments (none, etching, priming, or etching and priming) on enamel and dentin of human teeth were measured using the Swiss shear test design. Three adhesives (Permaflo DC, Panavia F 2.0, and Panavia V5) and one self-adhesive cement (Panavia SA plus) were included in this study. The interface of the cement and the tooth surface with the different pre-treatments was analyzed using SEM. pH values of the cements and primers were measured. RESULTS. The highest bond strength values for all cements were achieved with etching and primer on enamel ($25.6{\pm}5.3-32.3{\pm}10.4MPa$). On dentin, etching and priming produced the highest bond strength values for all cements ($8.6{\pm}2.9-11.7{\pm}3.5MPa$) except for Panavia V5, which achieved significantly higher bond strengths when pre-treated with primer only ($15.3{\pm}4.1MPa$). Shear bond strength values were correlated with the micro-retentive surface topography of enamel and the tag length on dentin except for Panavia V5, which revealed the highest bond strength with primer application only without etching, resulting in short but sturdy tags. CONCLUSION. The highest bond strength can be achieved for Panavia F 2.0, Permaflo DC, and Panavia SA plus when the tooth substrate is previously etched and the respective primer is applied. The new cement Panavia V5 displayed low technique-sensitivity and attained significantly higher adhesion of all tested cements to dentin when only primer was applied.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.2
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• pp.225-233
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• 1994

The restorations of the severely damaged teeth by post core have been increased with the developement of endodontic procedures. But high failure rates of these procedures being reported, various restorative modifications were induced for successful treatments. Cast post-core and prefabricated post with core buildups are choice of treatment. The main causes of failure of the restorations are the fracture of post and core, root fracture, and recurrent caries due to microleakage. Recently, the acid etching technique and the use of dentin bonding agent at tooth surface to reduce the possible microleakage at the tooth-restoration interfaces were introduced. The object of this study was to measure and compare the microleakage by the types and cementation methods of post-core. For this study, forty extracted human anterior teeth were selected for specimen. After cleansing and routine endodontic procedures, anatomic crowns of each specimen were removed at the level of 2mm above the cementoenamel junction. Canals were preparated for post insertion and specimens were divided into four groups randomly. Post-cores were fabricated according to method for each group. Microleakage was measured by length of dye penetration at the tooth-restoration interfaces with measuring microscope at 50 magnification. Oneway ANOVA and t-test were performed for statistical analysis of resulting data. The following results were obtained from this study. 1. There wert significant statistical differences in degree of microleakage between each group (p<0.01). 2. Cast post-core cemented with ZPC (Group I) showed the most severe microleakage pattern$(1.5547{\pm}0.0872mm)$, and cast post-core cemented with adhesive resin cement after tooth surface treatment with dentin bonding agent (Group II) showed the least microleakage $(0.1497{\pm}0.0872mm)$. 3. Group IV revealed less dye penetrations than group III, but no statistical significance was seen between two groups.

• The Journal of Advanced Prosthodontics
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• v.5 no.3
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• pp.234-240
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• 2013

PURPOSE. This study evaluated the effectiveness of various methods for removing provisional cement from implant abutments, and what effect these methods have on the retention of prosthesis during the definitive cementation. MATERIALS AND METHODS. Forty implant fixture analogues and abutments were embedded in resin blocks. Forty cast crowns were fabricated and divided into 4 groups each containing 10 implants. Group A was cemented directly with the definitive cement (Cem-Implant). The remainder were cemented with provisional cement (Temp-Bond NE), and classified according to the method for cleaning the abutments. Group B used a plastic curette and wet gauze, Group C used a rubber cup and pumice, and Group D used an airborne particle abrasion technique. The abutments were observed using a stereomicroscope after removing the provisional cement. The tensile bond strength was measured after the definitive cementation. Statistical analysis was performed using one-way analysis of variance test (${\alpha}$=.05). RESULTS. Group B clearly showed provisional cement remaining, whereas the other groups showed almost no cement. Groups A and B showed a relatively smooth surface. More roughness was observed in Group C, and apparent roughness was noted in Group D. The tensile bond strength tests revealed Group D to have significantly the highest tensile bond strength followed in order by Groups C, A and B. CONCLUSION. A plastic curette and wet gauze alone cannot effectively remove the residual provisional cement on the abutment. The definitive retention increased when the abutments were treated with rubber cup/pumice or airborne particle abraded to remove the provisional cement.

• The Journal of the Korean dental association
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• v.22 no.9 s.184
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• pp.803-811
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• 1984

The purpose of this study was to research how temporary cementation effected on the bond strength of permanent cementation. Zinc phosphate, polycarboxylate and EBA ZOE cements were used as permanent cements, and as temporary cements Nogenol, Tempak and Dycal were used. The ninety six (96) specimens were prepared to measure the bond strength of permanent cements after treated with temporary cements for one week. The tensile stregths were measured with an Instron Universal Test Machine. The results of this study were obtained as follows: 1. With zinc phosphate cement, there was a tendency that the bond strengths of the group of temporarily cemented with Nogenol were increased, meanwhile they were decreased a little in the groups of Dycal and Tempak than those of the control group. 2. With polycarboxylate cement, there was a tendency that the bond strengths of the Control group were higher than those of experimental groups and they were decreased in order of Tempak, Noginol, and Dycal. 3. With EBA ZOE cement, there was a tendency that the bond strengths of the group of temporarily cemented with Tempak were increased a little, meanwhile they were decreased a little in the groups of Nogenol and Dycal than those of the Control group. 4. Among the permanent cements, the bond strengths of polycarbosylate cement were the highest and were followed in order of zinc phosphate cement and EBA ZOE cement.

• The Journal of Advanced Prosthodontics
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• v.9 no.6
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• pp.439-446
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• 2017

PURPOSE. To evaluate the effects of different surface treatments on the bond strength of novel CAD/CAM restorative materials to resin cement by four point bending test. MATERIALS AND METHODS. The CAD/CAM materials under investigation were e.max CAD, Mark II, Lava Ultimate, and Enamic. A total of 400 bar specimens ($4{\times}1.2{\times}12mm$) (n=10) milled from the CAD/CAM blocks underwent various pretreatments (no pretreatment (C), hydrofluoric acid (A), hydrofluoric acid + universal adhesive (Scotchbond) (AS), sandblasting (Sb), and sandblasting + universal adhesive (SbS)). The bars were luted end-to-end on the prepared surfaces with a dual curing adhesive resin cement (Variolink N, Ivoclar Vivadent) on the custom-made stainless steel mold. Ten test specimens for each treatment and material combination were performed with four point bending test method. Data were analyzed using ANOVA and Tukey's test. RESULTS. The surface treatment and type of CAD/CAM restorative material showed a significant effect on the four point bending strength (FPBS) (P<.001). For LDC, AS surface treatment showed the highest FPBS results ($100.31{\pm}10.7MPa$) and the lowest values were obtained in RNC ($23.63{\pm}9.0MPa$) for control group. SEM analyses showed that the surface topography of CAD/CAM restorative materials was modified after treatments. CONCLUSION. The surface treatment of sandblasting or HF acid etching in combination with a universal adhesive containing MDP can be suggested for the adhesive cementation of the novel CAD/CAM restorative materials.

• The Journal of Advanced Prosthodontics
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• v.8 no.6
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• pp.449-456
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• 2016

PURPOSE. This in vitro study evaluated the effects of four different cements on the color attributes of a zirconia ceramic. MATERIALS AND METHODS. 40 zirconia ceramic disk specimens (0.5 mm thickness, 10 mm diameter, 0.1 mm cement space) were fabricated by a computer-aided design and computer-aided manufacturing system. The specimens were divided into 4 groups of 10 specimens and cemented to composite substrates using four different cements including: Glass Ionomer, Panavia F2.0, Zinc Phosphate, and TempBond. The $L^*$, $a^*$, and $b^*$ color attributes of the specimens were measured before and after cementation by a spectrophotometer. Additionally, ${\Delta}E$ values were measured to determine color changes for the groups and then compared with the perceptional threshold of ${\Delta}E=3.3$. Repeated Measures ANOVA, Tukey Post Hoc, Bonferroni, One-way ANOVA, and One-sample t-test tests were used to analyze the data. All tests were carried out at the 0.05 level of significance. RESULTS. Statistically significant differences were detected in the ${\Delta}E$ values for Zinc Phosphate (P<.0001) and TempBond (P<.0001) groups. However, there were no statistically significant differences in this respect for Glass Ionomer (P=.99) and Panavia F2.0 (P=1) groups. The means and standard deviations of the ${\Delta}E$ values for Glass Ionomer, Panavia F2.0, Zinc Phosphate, and Tempbond groups were $2.11{\pm}0.66$, $0.94{\pm}0.39$, $5.77{\pm}0.83$, and $7.50{\pm}1.16$ Unit, respectively. CONCLUSION. Within the limitations of this study, it was concluded that Zinc Phosphate and Tempbond cements affected the color attributes of the tested zirconia ceramic beyond the perceptional threshold. However, Glass Ionomer and Panavia F2.0 cements created acceptable color changes.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.6
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• pp.4276-4283
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• 2015

The purpose of this research is to identify the effectiveness of injection with soil conditions by injecting CaCO3(created by microorganism reaction), which was recreated with equipment in similar situ condition. To analyze our research, we made 2 cases of single-layer (SP, SW) in D 150mm ${\times}$ H 300mm. Layers were made by RC 70, 80, 85, 90, 95% of soil condition. We measured uniaxial compression strength with cone penetrometer and watched injection range by checking a bulb formation around the injection nozzle. As a result, the relative compaction(RC) in more 85% were not injected in SW, we could identify the effect of bio-grouting technology on ground in relative compaction(RC) of injection ratio and cementation range.

• The Journal of Advanced Prosthodontics
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• v.15 no.2
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• pp.93-100
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• 2023

PURPOSE. The aim of this study is to evaluate the effect of resin cement color, cement thickness, and thermocycling on the final color of monolithic lithium disilicate crowns. MATERIALS AND METHODS. A total of ninety prepared central incisors of typodont teeth were restored with lithium disilicate crowns which have different cement thicknesses (40 ㎛, 80 ㎛, and 120 ㎛) and cement shades (clear, yellow, and white). Color parameters of restorations were measured with a spectrophotometer in three different steps 1) before cementing 2) after cementing and 3) after thermocycling with 10000 cycles. Color differences (ΔE₀₀) were calculated with the CIEDE2000 formula and evaluated according to perceptibility (0.8) and acceptability (1.8) thresholds. The ΔE₀₀ data were analyzed by using two-way ANOVA before and after thermocycling (α = .05). RESULTS. There was no interaction between the cement shade and the cement thickness factors. After cementation, the mean ΔE₀₀ was under the perceptibility threshold in the group of 40 ㎛ cement thickness and clear cement while it was between the perceptibility and acceptability thresholds (0.8 < ΔE₀₀ < 1.8) for all other groups. After thermocycling, the ΔE₀₀ values were between the perceptibility and acceptability thresholds for all experimental groups. Although there were no significant differences among the groups, thermocycling increased the color difference values. CONCLUSION. The cementation of restorations with clear, yellow, and white resin cements resulted in color differences with uncemented restorations except for the group cemented with clear cement in 40 ㎛ cement thickness. All study groups revealed perceptible color change after thermocycling.

• Journal of the Korean Geotechnical Society
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• v.24 no.4
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• pp.67-78
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• 2008

In this study, artificial cemented sand made of a few portland cement and Nak-Dong river sand was researched closely to investigate cementing effect quantitatively through unconfined tests and triaxial tests. The peak strength and elastic modulus increased and dilation of cemented sand was restricted by the cementation, but after breakage of the cementation, dilation and negative excess pore water pressure increased. In stress-strain curve, strain-softening behavior appeared in drained condition but strain-hardening behavior was appeared in undrained condition as a result of the increase of effective stress. The test was quantitatively analyzed by multiple regression models, correlating each response variable with input variable. The equations are valid only over the range investigated. Its adjusted coefficient of determination was $0.81{\sim}0.91$, and dry density is important factor for estimating strength of cemented sand.