• Journal of Technologic Dentistry
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• v.42 no.3
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• pp.213-219
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• 2020

Purpose: This study aimed to identify the impact of physical surface roughing with a polishing tool onto the pre-sintering yttria-stabilized tetragonal zirconia polycrystals (TZP) core and liner treatment for chemical bonding on the bond strength of TZP core and veneering ceramic. Methods: Overall, 80 specimens were classified into two groups (non-liner, NL; and usingliner, UL ) depending on the use of liner, and these two groups were then subclassified into four groups depending on the polishing tool used. (1) Non-liner groups: NS, non-liner+stone point; NC, non-liner+carbide bur; NP, non-liner+paper cone point; NT, non-liner+silicon point. (2) Using-liner groups: US, using-liner+stone point; UC, using-liner+carbide bur; UP, usingliner+paper cone point; UT, using-liner+silicon point. The pre-sintering surface roughing values and shapes were observed, and after burning up the veneering ceramic, the shear bond strength was measured using a universal testing machine. For significance testing, a one-way analysis of variance and Tukey's multiple comparison test were conducted. An optical microscope was used to observe the fracture plane, and the following results were obtained. Results: Surface roughness NP (4.09±0.51 ㎛) represented a higher value than other groups (p<0.001). In shear bond strength, NS (35.21±1.44 MPa) of the NL group showed the highest bond strength (p<0.001). The UL group did not show a statistically significant difference between groups (p=0.612). Conclusion: Our study findings reveal that the bond strength of TZP core and veneering ceramic was improved by pre-sintering physical surface treatment than by chemical bonding with liner surface treatment.

• The Journal of Korean Academy of Prosthodontics
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• v.46 no.4
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• pp.372-380
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• 2008

Purpose: The purpose of this study was to evaluate the effect of various methods of dentin bonding agent application on microtensile bond strength between dentin and resin, using a 2-step etch-and-rinse dentin bonding agent. Material and methods: Twenty freshly extracted human molars were obtained and divided into 4 groups of 5 teeth. 2-step etch-and-rinse dentin bonding agent was used for all groups. The control specimens were prepared using a direct immediate bonding technique. The delayed dentin sealing (A, C) specimens were prepared using an indirect approach with delayed dentin sealing. For group A, resin was built-up on uncured dentin bonding agent, and for group C, resin was built-up on pre-cured dentin bonding agent. Preparation of the immediate dentin sealing (B) specimens also used an indirect approach with immediate dentin sealing immediately following preparation. All teeth were prepared for a microtensile bond strength test. Specimens were stored in water for 24 hours. Ten beams (1.0 ${\times}$ 1.0 ${\times}$ 11 mm) from each tooth were selected for testing. Bond strength data (MPa) were analyzed with a one-way ANOVA test, and post hoc comparison was done using the Scheffe's test. Results: The mean microtensile bond strengths of control group, B and C (DDS with pre-cure) were not statisticaaly different from each other at 32.7, 33.3, 34.2 MPa. the bond strength for group A (DDS without pre-cure), 19.5 MPa, was statistically different (P < .01) from the other 3 groups. Conclusion: When preparing teeth for indirect bonded restorations, DDS with pre-curing dentin bonding agent and IDS results in the same bond strength between dentin and resin. On the contrast, the bond strength was decreased when DDS without pre-curing dentin bonding agent was used.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.701-704
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• 1999

The purpose of this study was to investigate the effectiveness of the flexural rehabilitation of the pre-loaded reinforced concrete beams strengthened by the steel plate. Main test parameters were the existence and the magnitude of the pre-loading at the flexural of rehabilitation and the tensile reinforcement ratio of the specimens. Seven beam specimens were tested to investigate the effectiveness of the rehabilitation method. Test results showed that the ultimate load capacities of the pre-loaded specimens were higher than not-pre-loaded specimens at the rehabilitation. The cause of the pharameter was analyzed if is suggested that the bond failure between the concrete and the strengthening steel plate occured prior to the yielding of the tension reinforcement. The member flexural stiffnesses, were similar regardless of the load conditions at retrofit and failure modes showed brittle aspect caused by rip-off failure.

• The korean journal of orthodontics
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• v.44 no.1
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• pp.44-49
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• 2014

Objective: To evaluate the effects of ultrasonic instrumentation with different scaler-tip angulations on the shear bond strength (SBS) and bond failure mode of metallic orthodontic brackets. Methods: Adhesive pre-coated metallic brackets were bonded to 72 extracted human premolars embedded in autopolymerizing acrylic resin. The teeth were randomly divided into 3 groups (n = 24 each) to undergo no treatment (control group) or ultrasonic instrumentation with a scaler-tip angulation of $45^{\circ}$ ($45^{\circ}$-angulation group) or $0^{\circ}$ ($0^{\circ}$-angulation group). SBS was tested in a universal testing machine, and adhesive remnant index (ARI) scores were recorded. The Kruskal-Wallis test and Mann-Whitney U-test were used for statistical analysis. Results: The control group had a significantly higher mean SBS value than the treated groups, which showed no significant differences in their mean SBS values. The ARI scores were not significantly different among the groups. Conclusions: Ultrasonic instrumentation around the bracket base reduces the SBS of metallic orthodontic brackets, emphasizing the need for caution during professional oral hygiene procedures in orthodontic patients. The scaler-tip angulation does not influence the SBS reduction and bond failure mode of such brackets.

• Restorative Dentistry and Endodontics
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• v.34 no.1
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• pp.30-37
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• 2009

The purpose of this study was to evaluate the effect of pre-heating on some physical properties of composite resin. Eighty extracted, noncarious human molars were used in the present study. Four different temperatures of composite resin were used: $4^{\circ}C$, $17^{\circ}C$, $48^{\circ}C$, and $56^{\circ}C$. The $4^{\circ}C$ and $17^{\circ}C$ values represented the refrigerator storage temperature and room temperature respectively. For $48^{\circ}C$ and $56^{\circ}C$, composite resin was heated to the temperatures. As physical properties of composite resin, shear bond strength, microhardness, and degree of conversion were measured. The data for each group were subjected to one-way ANOVAs followed by the Tukey's HSD test at 95% confidence level. Both in enamel and dentin, among composite resin of $4^{\circ}C$, $17^{\circ}C$ $;48^{\circ}C$, and $56^{\circ}C$, the pre-heated composite resin up to $56^{\circ}C$ revealed the highest shear bond strength, and pre-heated composite resin to the higher temperature revealed higher shear bond strength. Microhardness value was also higher with composite resin of higher temperature. Degree of conversion was also higher with composite resin of the higher temperature. In this study, it seems that pre-heating composite resin up to the higher temperature may show higher shear bond strength, higher microhardness value, and higher degree of conversion. Therefore, when using composite resin in the clinic, preheating the composite resin could be recommended to have enhanced physical properties of it.

• The Journal of Advanced Prosthodontics
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• v.6 no.6
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• pp.434-443
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• 2014

PURPOSE. The purpose of this study was to evaluate and compare the effects of different surface pretreatment techniques on the surface roughness and shear bond strength of a new self-adhering flowable composite resin for use with lithium disilicate-reinforced CAD/CAM ceramic material. MATERIALS AND METHODS. A total of one hundred thirty lithium disilicate CAD/CAM ceramic plates with dimensions of $6mm{\times}4mm$ and 3 mm thick were prepared. Specimens were then assigned into five groups (n=26) as follows: untreated control, coating with $30{\mu}m$ silica oxide particles ($Cojet^{TM}$ Sand), 9.6% hydrofluoric acid etching, Er:YAG laser irradiation, and grinding with a high-speed fine diamond bur. A self-adhering flowable composite resin (Vertise Flow) was applied onto the pre-treated ceramic plates using the Ultradent shear bond Teflon mold system. Surface roughness was measured by atomic force microscopy. Shear bond strength test were performed using a universal testing machine at a crosshead speed of 1 mm/min. Surface roughness data were analyzed by one-way ANOVA and the Tukey HSD tests. Shear bond strength test values were analyzed by Kruskal-Wallis and Mann-Whitney U tests at ${\alpha}=.05$. RESULTS. Hydrofluoric acid etching and grinding with high-speed fine diamond bur produced significantly higher surface roughness than the other pretreatment groups (P<.05). Hydrofluoric acid etching and silica coating yielded the highest shear bond strength values (P<.001). CONCLUSION. Self-adhering flowable composite resin used as repair composite resin exhibited very low bond strength irrespective of the surface pretreatments used.

• Computers and Concrete
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• v.1 no.2
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• pp.151-168
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• 2004

A two-dimensional nonlinear finite element model is developed to simulate time-dependent cracking of reinforced concrete members under service loads. To predict localized cracking, the crack band model is employed to model individual crack opening. In conjunction with the crack band model, a bond-interface element is used to model the slip between concrete and reinforcing steel permitting large slip displacements between the concrete element nodes and the steel truss element nodes at crack openings. The time-dependent effects of concrete creep and shrinkage are incorporated into the smeared crack model as inelastic pre-strains in an iterative solution procedure. Two test examples are shown to verify the finite element model with good agreement between the model and the observed test results.

• Restorative Dentistry and Endodontics
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• v.37 no.4
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• pp.207-214
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• 2012

Objectives: This study evaluated the influence of chlorhexidine (CHX) on the microtensile bonds strength (${\mu}TBS$) of resin core with two adhesive systems to dentin in endodontic cavities. Materials and Methods: Flat dentinal surfaces in 40 molar endodontic cavities were treated with self-etch adhesive system, Contax (DMG) and total-etch adhesive system, Adper Single Bond 2 (3M ESPE) after the following surface treatments: (1) Priming only (Contax), (2) CHX for 15 sec + rinsing + priming (Contax), (3) Etching with priming (Adper Single Bond 2), (4) Etching + CHX for 15 sec + rinsing + priming (Adper Single Bond 2). Resin composite build-ups were made with LuxaCore (DMG) using a bulk method and polymerized for 40 sec. For each condition, half of specimens were submitted to ${\mu}TBS$ after 24 hr storage and half of them were submitted to thermocycling of 10,000 cycles between $5^{\circ}C$ and $55^{\circ}C$ before testing. The data were analyzed using ANOVA and independent t-test at a significance level of 95%. Results: CHX pre-treatment did not affect the bond strength of specimens tested at the immediate testing period, regardless of dentin surface treatments. However, after 10,000 thermocycling, all groups showed reduced bond strength. The amount of reduction was greater in groups without CHX treatments than groups with CHX treatment. These characteristics were the same in both self-etch adhesive system and total-etch adhesive system. Conclusions: 2% CHX application for 15 sec proved to alleviate the decrease of bond strength of dentin bonding systems. No significant difference was shown in ${\mu}TBS$ between total-etching system and self-etching system.

• The Journal of Advanced Prosthodontics
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• v.10 no.6
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• pp.408-414
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• 2018

PURPOSE. This study aimed to assess the effect of non-thermal plasma on the shear bond strength of resin cements to polyetherketoneketone (PEKK) in comparison to other surface treatment methods. MATERIALS AND METHODS. Eighty PEKK discs were subjected to different surface treatments: (1) Untreated (UT); (2) Non-thermal plasma (NTP); (3) Sandblasting with $50{\mu}m$ $Al_2O_3$ particles (SB); and (4) Sandblasting + Non-thermal plasma (SB+NTP). After each surface treatment, the contact angle was measured. Surface conditioning with Visio.Link was applied in all groups after pre-treatment. RelyX Unicem resin cement was bonded onto the PEKK specimens. After fabrication of the specimens, half of each group (n=10) was initially tested, while the other half was subjected to thermocycling ($5^{\circ}C$ to $55^{\circ}C$ at 10,000 cycles). Shear bond strength (SBS) testing was performed using a universal testing machine, and failure modes were assessed using stereomicroscopy. The SBS results were analyzed statistically using one-way ANOVA followed by Tukey's post hoc test. Independent t-test was used to examine the effect of thermocycling (P<.05). RESULTS. The highest SBS values with or without thermocycling were observed with PEKK specimens that were treated with SB+NTP followed by the SB group. The lowest SBS results were observed in the UT groups. CONCLUSION. The shear bond strength between PEKK and resin cements was improved using non-thermal plasma treatment in combination with sandblasting.

• Advances in concrete construction
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• v.6 no.1
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• pp.47-68
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• 2018

This article reports the utilization of fly ash (FA) waste product from industry and silpozz which is an agro-waste from agriculture as an environmental friendly material in construction industry. The evaluation of strength and durability study was observed using FA and silpozz as a partial replacement of Ordinary Portland Cement (OPC). The studied parameters are compressive strength, flexural strength, split tensile strength and bond strength as well as the durability study involves the acid soluble chloride (ASC), water soluble chloride (WSC), water absorption and sorptivity. Scanning electron microscopy (SEM) and XRD of selected samples are also done. It reveals from the test results that the deterioration factor (DF) in compressive strength is 4% at 365 days. The DF of split tensile strength and flexural strength is 0.96% and 0.6% at 90 days respectively. The minimum slip is 1mm and 1.1mm after 28 days of testing bond strength for NWC and SWC sample respectively. The percentage decrease in bond strength is 10.35% for 28 days SWC samples. The pre-cast blended concrete samples performed better to chloride diffusion. Modulus of elasticity of SWC samples are also studied.The water absorption and sorptivity tests are conducted after 28 days of curing.