Changes in micro-TBS to pulp chamber dentin after the application of NaOCl & reversal effect by using sodium ascorbate / 대한치과보존학회지

Clinical suggestion for the limitation of application time of NaOCl solution is needed to avoid large reductions in resin-dentin bond strength. The aim of this study was to measure the change of micro-tensile bond strength after the various application time of 5.25% NaOCl solution to pulp chamber dentin in endodontic access cavity, and to evaluate the effect of 10% sodium ascorbate application for 10 min on bond strength after the treatment of 5.25% NaOCl solution. In this experiment, there were no statistical differences(p>0.05) in bond strengths between upper chamber dentin and lower chamber dentin. NaOCl-treated group for 20 min did not show any significant decrease(p>0.05) in bond strength than non-treated control group. In contrast to that, bond strengths of NaOCl-treated groups for 40 & 80 min were significantly lower(p<0.05) than that of non-treated control group. 10% sodium ascorbate retreated group for 10 min after 5.25% NaOCl application for 40 min to chamber dentin showed the recovery of bond strength significantly. However, the bond strength of sodium ascorbate retreated group after 5.25% NaOCl application for 80 min was still significantly lower(p<0.05) compared to the non-treated control group, which means the reductions in resin-dentin bond strength were not fully reversed. On the contrary, sodium ascorbate retreated group after 5.25% NaOCl application for 5 min showed significantly higher(p<0.05) bond strength compared to the control group, which demonstrates its superior recovery effect. In SEM exminations of specimens retreated with 10% sodium ascorbate after NaOCl application for 40 & 80 min showed that resin tags were formed clearly and densely, but weakly in density and homogeneity of individual resin tag compared to the control specimen.

Effect of calcium hydroxide on bond strength of dentin bonding systems / 대한치과보존학회지

The purpose of this study was to investigate the effect of calcium hydroxide on dentin bonding strength of various dentin bonding systems as a function of time in composite resin restoration. Dentin adhesives used in this study were Scotchbond Multipurpose, Single Bond, SE Bond and Prompt L-Pop. Flat dentin surfaces adjacent to pulp chamber were created, then Ca(OH)2 and saline were mixed and applied on dentin surface of experimental group, then IRM was used to cover the mixture on dentin surface and the specimens were stored at 36.5degrees C for experiment period (7 days, 30 days). After removing IRM and Ca(OH)2, each dentin adhesives were treated on dentin surfaces. Composite resin (Z-250, 3M) was placed with 5 mm height and was light-cured for 20 seconds. After stored in distilled water for 24 hours, each dentin-composite bonded spicemen was embedded in epoxy resin and sectioned into 1.0 x 1.0 mm2 cross section composite-dentin beams. Specimen was mounted on zig of Universal testing machine and microTBS test was performed. SEM analysis was performed to examine the fractured surfaces. The results suggested that applying calcium hydroxide did not show significant difference in dentin bonding strength.

Effect of calcium hydroxide on bond strength of dentin bonding systems / 대한치과보존학회지

The purpose of this study was to investigate the effect of calcium hydroxide on dentin bonding strength of various dentin bonding systems as a function of time in composite resin restoration. Dentin adhesives used in this study were Scotchbond Multipurpose, Single Bond, SE Bond and Prompt L-Pop. Flat dentin surfaces adjacent to pulp chamber were created, then Ca(OH)2 and saline were mixed and applied on dentin surface of experimental group, then IRM was used to cover the mixture on dentin surface and the specimens were stored at 36.5degrees C for experiment period (7 days, 30 days). After removing IRM and Ca(OH)2, each dentin adhesives were treated on dentin surfaces. Composite resin (Z-250, 3M) was placed with 5 mm height and was light-cured for 20 seconds. After stored in distilled water for 24 hours, each dentin-composite bonded spicemen was embedded in epoxy resin and sectioned into 1.0 x 1.0 mm2 cross section composite-dentin beams. Specimen was mounted on zig of Universal testing machine and microTBS test was performed. SEM analysis was performed to examine the fractured surfaces. The results suggested that applying calcium hydroxide did not show significant difference in dentin bonding strength.

The effect of thermocycling on the durability of dentin adhesive systems / 대한치과보존학회지

The objectives of this study was to evaluate the effect of thermocycling on the microTBS (microtensile bond strength) to dentin with four different adhesive systems to examine the bonding durability. Freshly extracted 3rd molar teeth were exposed occlusal dentin surfaces, and randomly distributed into 8 adhesive groups: 3-steps total-etching (Scotchbond Multi-Purpose Plus; SM, All Bond-2; AB), 2-steps total-etching (Single Bond; SB, One Step plus; OS), 2-steps self-etching (Clearfil SE Bond; SE, AdheSE; AD) and single-step self-etching systems (Promp L-Pop; PL, Xeno III; XE). Each adhesive system in 8 adhesives groups was applied on prepared dentin surface as an instruction and resin composite (Z250) was placed incrementally and light-cured. The bonded specimens were sectioned with low-speed diamond saw to obtain 1 x 1 mm sticks after 24 hours of storage at 37degrees C distilled water and proceeded thermocycling at the pre-determined cycles of 0, 1,000 and 2,000. The microTBS test was carried out with EZ-tester at 1 mm/min. The results of bond strength test were statistically analyzed using one-way ANOVA/Duncan's test at the alpha < 0.05 confidence level. Also, the fracture mode of debonded surface and the interface were examined under SEM. The results of this study were as follows; 1. 3-step total etching adhesives showed stable, but bond strength of 2-step adhesives were decreased as thermocycling stress. 2. SE showed the highest bond strength, but single step adhesives (PL, XE) had the lowest value both before and after thermocycling. 3. Most of adhesives showed adhesive failure. The total-etching systems were prone to adhesive failure and the single-step systems were mixed failure after thermocycling. Within limited results of this study, the bond strength of adhesive system was material specific and the bonding durability was affected by the bonding step/procedure of adhesive. Simplified bonding procedures do not necessarily imply improved bonding performance.

The effect of thermocycling on the durability of dentin adhesive systems / 대한치과보존학회지

The objectives of this study was to evaluate the effect of thermocycling on the microTBS (microtensile bond strength) to dentin with four different adhesive systems to examine the bonding durability. Freshly extracted 3rd molar teeth were exposed occlusal dentin surfaces, and randomly distributed into 8 adhesive groups: 3-steps total-etching (Scotchbond Multi-Purpose Plus; SM, All Bond-2; AB), 2-steps total-etching (Single Bond; SB, One Step plus; OS), 2-steps self-etching (Clearfil SE Bond; SE, AdheSE; AD) and single-step self-etching systems (Promp L-Pop; PL, Xeno III; XE). Each adhesive system in 8 adhesives groups was applied on prepared dentin surface as an instruction and resin composite (Z250) was placed incrementally and light-cured. The bonded specimens were sectioned with low-speed diamond saw to obtain 1 x 1 mm sticks after 24 hours of storage at 37degrees C distilled water and proceeded thermocycling at the pre-determined cycles of 0, 1,000 and 2,000. The microTBS test was carried out with EZ-tester at 1 mm/min. The results of bond strength test were statistically analyzed using one-way ANOVA/Duncan's test at the alpha < 0.05 confidence level. Also, the fracture mode of debonded surface and the interface were examined under SEM. The results of this study were as follows; 1. 3-step total etching adhesives showed stable, but bond strength of 2-step adhesives were decreased as thermocycling stress. 2. SE showed the highest bond strength, but single step adhesives (PL, XE) had the lowest value both before and after thermocycling. 3. Most of adhesives showed adhesive failure. The total-etching systems were prone to adhesive failure and the single-step systems were mixed failure after thermocycling. Within limited results of this study, the bond strength of adhesive system was material specific and the bonding durability was affected by the bonding step/procedure of adhesive. Simplified bonding procedures do not necessarily imply improved bonding performance.

The bonding durability of total etching adhesives on dentin / 대한치과보존학회지

The purpose of this study was to evaluate the effect of different etching times on microtensile bond strength (microTBS) to dentin both initial and after thermocycling with 3 different types of total-etching adhesives. Fifty four teeth were divided into 18 groups by etching times (5, 15, 25 sec), adhesives types (Scotchbond Multipurpose (SM), Single Bond (SB), One-Step (OS)), and number of thermocycling (0, 2,000 cycles). Flat dentin surfaces were prepared on mid-coronal dentin of extracted third molars. After exposed fresh dentin surfaces were polished with 600-grit SiC papers, each specimen was acid-etched with 35% phosphoric acid (5, 15, 25 sec) and bonded with 3 different types of total etching adhesives respectively. Then, hybrid composite Z-250 was built up. Half of them were not thermocycled (control group) and the others were subjected to 2,000 thermocycle (experimental group). They were sectioned occluso-gingivally into 1.0 x 1.0 mm2 composite-dentin beams and tested with universal testing machine at a crosshead speed of 1.0 mm/min. Within limited data of this study, the results were as follows 1. There was no statistically significant difference in microTBS between the thermocycled and non-thermocycled groups, except for both SM and SB etched for 25 sec. 2. In thermocycled SM and SB groups, bond strength decreased by extended etching time. In total etching systems, adhesive durability for dentin could be affected by type of solvents in adhesive and etching time. Especially, extended etching time may cause deteriorate effects on bond strength when ethanol-based adhesive was used.

Microtensile bond strength of single step adhesives to dentin / 대한치과보존학회지

This study compared the microtensile bond strength (microTBS) of three single step adhesives to dentin. Occlusal superficial dentin was exposed in fifteen human molars. They were assigned to three groups by used adhesives: Xeno group (Xeno III), Prompt group (Adper Prompt L-Pop), AQ group (AQ Bond). Each adhesive was applied to dentin surface, and composite of same manufacturer was constructed. The bonded specimens were sectioned into sticks with an interface area approximately 1 mm2, and subjected to microTBS testing with a crosshead speed of 1 mm/minute. The results of this study were as follows; 1. The microTBS to dentin was 48.78 +/- 9.83 MPa for Xeno III, 30.22 +/- 4.52 MPa for Adper Prompt L-Pop, and 26.31 +/- 7.07 MPa for AQ Bond. 2. The mean microTBS of Xeno group was significantly higher than that of Prompt group and AQ group (p < 0.05). 3. There was no significant difference between the microTBS of Prompt group and AQ group.