G-Bond Research Articles

Marginal integrity of low-shrinking versus methacrylate-based composite: effect of different one-step self-etch adhesives.

The aim of the study was to evaluate the influence of composite type and adhesive system on the quality of marginal adaptation in standardized Class V cavities before and after thermo-mechanical loading (TML). The cavities were restored using different combinations of three adhesive systems [(Silorane System Adhesive (SSA), Clearfil S3 Bond (S3), G-Bond (G-B)] and two resin composite materials (Filtek Silorane, Clearfil AP-X). Six groups (n=10): Group A (SSA-Primer+SSA-Bond, Filtek Silorane), Group B (SSA-Primer+SSA-Bond, Clearfil AP-X), Group C (S3+SSA-Bond, Filtek Silorane), Group D (S3+SSA-Bond, Clearfil AP-X), Group E (G-B+SSA-Bond, Filtek Silorane) and Group F (G-B+SSA-Bond, Clearfil AP-X) were defined. Marginal adaptation was assessed on replicas in the SEM at 200×magnification before and after TML (3000×5-55°C, 1.2 106×49N; 1.7Hz) under simulated dentinal fluid. The highest scores of continuous margins (%CM) were observed in the group F (G-B+SSA-Bond, Clearfil AP-X: before loading 96.4 (±3.2)/after loading 90.8 (±7.0)). A significant effect of adhesive system, composite type and loading interval was observed on the results (p<0.05). Significantly lower scores of %CM were observed for silorane-based composite (Filtek Silorane) after TML in comparison with methacrylate-based composite (Clearfil AP-X) considering total marginal length (p<0.05). For both Filtek Silorane and Clearfil AP-X, G-Bond performed significantly better than SSA-Primer and Clearfil S3 Bond (p<0.05). For all combinations of one-step self-etch adhesives and SSA-Bond resin coating, silorane-based low-shrinking composite exhibited inferior marginal adaptation than did the methacrylate-based composite.

Cytotoxic Effects of One-step Self-etching Dental Adhesives on Human Periodontal Ligament Fibroblasts In Vitro.

To evaluate the potential cytotoxic effects of four one-step self-etching dental adhesives [Adper Easy One (AEO), iBond (IB), Clearfil S³ Bond (CSB), and G-Bond (GB)] on cultured human periodontal ligament fibroblasts. Cured adhesives were immersed in complete DMEM or deionized water and maintained at 37°C for 24 h, followed by sterilization. The deionized water-based extract was used for Fourier transform infrared spectroscopy analysis. The DMEM-based extract was diluted into various concentrations for cytotoxicity tests. The viability, integrity, and apoptosis of cultured human periodontal ligament fibroblasts upon treatment with the extracts were determined using the CCK-8 assay, microscopy, and flow cytometry. All of the four adhesives induced cell viability loss, cell morphology alteration, and cell death. GB showed the greatest cytotoxicity by inducing cell apoptosis and necrosis, while IB had the weakest cytotoxic effect on the cultured cells. All tested dental adhesives have significant adverse effects on cell viability. Therefore, precautions should be taken to protect the periodontal tissues when dental adhesives are applied in the clinic.

The Effect of Decalcified Root Surfaces on Dentinal Bond Strength

Microtensile bond strengths of current dentin adhesives to intact and decalcified root surfaces were evaluated. Two hundred and twenty-four extracted human incisors were divided into two groups as intact (IRD) and decalcified (DRD). The roots of DRD teeth were placed in a demineralization solution to produce artificial carious-like lesions. Root surfaces were slightly ground and treated with either Scotchbond Multi-Purpose (SMP), Adper Single Bond Plus (SBP), Adper Easy Bond (AEB), Scotchbond SE (SSE), Clearfil SE Bond (CSE), Clearfil Protect Bond (CPB), Clearfil Tri-S Bond (CTS), FL-Bond II (FLB), XP Bond (XPB), iBond (IB), AdheSE Bond (ASE), Optibond Solo Plus (OSP), Prelude Dental Adhesive (PDA), and G-Bond (GB). Composite build-ups were formed on the bonded surfaces. After thermocycling, hour-glass shaped specimens with an area of 1 mm2 at the bonded interface were subjected to microtensile testing. Resin–dentin interfaces were observed with SEM. Kruskal Wallis and Mann Whitney-U tests were used for statistical analysis. There was not significant difference between bond strengths to intact and decalcified dentin, with the exception of ASE and CSE, which had higher values to IRD (p < 0.05). SSE and CTS were the adhesives that showed higher bond strengths to DRD than to IRD, however the difference was not significant (p > 0.05). The self-etch adhesives performed better on both IRD and DRD surfaces than etch-and-rinse systems.

Effects of type I collagen degradation on the durability of three adhesive systems in the early phase of dentin bonding.

ObjectiveThis study was designed to evaluate the effects of type I collagen degradation on the durability of three adhesive systems in the early phase of dentin bonding.MethodsBonded dentin specimens were prepared using three different types of adhesive systems. Micro-tensile bond strength and degradation of collagen were tested before, and after 1 month or 4 months of aging in artificial saliva. The relationship between micro-tensile bond strength and collagen degradation was analyzed by calculating their Pearson’s correlation coefficient.ResultsAging induced time-dependent reduction in micro-tensile bond strengths for all the tested adhesive systems, although such reduction for the single-step self-etching adhesive G-Bond (GB) was not statistically significant. The bond strength of the two-step self-etching primer adhesive system Clearfil SE Bond (SEB) was similar to that of the two-step etch-and-rinse self-priming adhesive system Single Bond 2 (SB), and they were both significantly reduced after one or four months of aging. A negative correlation was found between the degree of collagen degradation and magnitude of micro-tensile bond strength (r = - 0.65, p = 0.003). The Pearson’s correlation coefficient was 0.426, indicating that 42.6% of the aging-induced reduction in bond strength can be explained by the degradation of collagen.ConclusionsIn the early phase of dentin bonding, there was a negative correlation between the degree of collagen degradation and the magnitude of micro-tensile bond strength. The reduction of bond strength was accompanied by the degradation of collagen. These results provide evidence for the causative relationship between the degradation of collagen and the deterioration of dentin-adhesive interface.

İKİ SELF-ETCH BONDING SİSTEMİN BİYOUYUMLULUKLARININ VE BAĞLANMA DAYANIMLARININ DEĞERLENDİRİLMESİ

Objectives: The aim of this study was to evaluate the biocompatibility and dentin bond strengths of two different self-etch adhesive systems[Clearfil SE Bond (CSE) and G-Bond (GB)]. Materials and methods: Non-carious 8 extracted human third molar teeth were used in this study. The occlusal surfaces of all teeth were ground perpendicular to the long axis of each tooth to expose a flat dentin surface. The teeth were divided into two groups and adhesive systems were applied according to the manufacturer's instructions to the oclusal surfaces of the teeth and restored with Gradia Direct composite resin. The samples were sectioned perpendicular to the adhesive interface to produce sticks (adhesive area: 1 mm2) and fifteen sticks were obtained for each group. All sticks submitted to microtensile bond strength test (Microtensile tester, Bisco, Schaumburg, IL, ABD). Data were analyzed using one-way varyans analysis ANOVA. An agar overlay test was used for the cytotoxicity evaluation. Cytotoxicity was examined by measuring the zones of cell decolorization and evaluating cell lysis by an inverted microscope after 24 hours. Data were analyzed using Kruskal wallis and Mann withney U test. Results: CSE showed higher dentin bond strength mean (23.5 MPa) than GB (18.9 MPa) (p < 0.05). Both bonding systems showed lower lysis scores than positive control material (p<0.001). Conclusions: The bonding agent which is higer bond strength may be prefered for a long-lasting restoration since there is no a statistically significant difference between toxicity of used two bonding systems

Influence of casein phosphopeptide-amorphous calcium phosphate application, smear layer removal, and storage time on resin-dentin bonding

The aim of this study is to evaluate the influence of Tooth Mousse (TM) application, smear layer removal, and storage time on resin-dentin microtensile bond strength (µTBS). Dentin specimens were divided into two groups: (1) smear layer covered; (2) smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were treated once with TM for 60 min. After bonding procedures using a two-step self-etching adhesive (Clearfil SE Bond (CSE); Kuraray Medical, Tokyo, Japan), an all-in-one adhesive (G-Bond (GB); GC Corp, Tokyo, Japan), and a total-etch adhesive (Adper Single Bond 2 (SB); 3M ESPE, St. Paul, MN, USA), the specimens were stored for 3 d or 6 months in deionized water at 37 °C, and µTBS was tested and analyzed. With the exception of SB (no TM application) and GB, the μTBS was significantly increased for CSE and SB using EDTA pre-conditioning and 3 d of storage (P≤0.001). Bond strength of GB decreased significantly when using EDTA (3 d storage, P<0.05). TM application only increased the μTBS of GB (no EDTA) and SB (with EDTA) after 3 d (P≤0.02). Comparing the adhesives after 3 d of storage, CSE exhibited the greatest μTBS values followed by GB and SB (P≤0.02). The factors of adhesive, EDTA, and TM did not show any significant impact on μTBS when specimens were stored for 6 months (P>0.05). The additional application of TM and EDTA for cavity preparation seems only to have a short-term effect, and no influence on µTBS of dentin bonds after a period of 6 months.

Evaluation of Degradation in Nanofilled Adhesive Resins Using Quantitative Light‐Induced Fluorescence

The aim of this study was to evaluate degradation in commercial dental nanofilled adhesive resins using quantitative light‐induced fluorescence (QLF). Three adhesives were selected: D/E resin (DR), Single Bond Plus (SB), and G‐Bond (GB). The adhesives were mixed with porphyrin for the QLF analysis. Specimens were prepared by dispensing blended adhesives into a flexible mold and polymerizing. Then, the QLF analysis of the specimens was done and the porphyrin values (Simple Plaque Score and ΔR) were measured. After thermocycling of the specimens (5000 cycles, 5 to 55°C) for the degradation, the specimens were assayed by QLF again. The porphyrin values were analyzed using paired t‐test at a 95% confidence level. A significant reduction in SPS was observed in all groups after thermocycling. The ΔR significantly decreased after thermocycling except area ΔR30 of SB group. Overall, porphyrin values decreased after thermocycling which indicates that the degradation of the adhesive resins may be measured by the change of porphyrin value. The QLF method could be used to evaluate the degradation of adhesive resin.

Resistance to Degradation of Resin-Dentin Bonds Produced by One-Step Self-Etch Adhesives

The objective of this article is to evaluate the resistance to degradation of resin-dentin bonds formed with three one-step adhesives. Flat, mid-coronal dentin surfaces were bonded with the self-etching adhesives [Tokuyama Bond Force (TBF), One Up Bond F Plus (OUB), and G-Bond (GB)]. The bonded teeth were subjected to fatigue loading, chemical degradation, and stored in distilled water for four time periods (up to 12 months). Specimens were tested for microtensile bond strength and microleakage. Fractographic analysis was performed by scanning electron microscopy. Bonded interfaces were examined by light microscopy using Masson's trichrome staining. An atomic force microscope was employed to analyze phase separation and surface nanoroughness (Ra) at the polymers. Vickers microhardness and the degree of the conversion (DC) were also determined. ANOVA and multiple comparisons tests were performed. Bond strength significantly decreased after the chemical challenge, but not after load cycling. Aging decreased bond strength after 6 months in TBF and GB, in OUB after 12 months. An increase of the nonresin protected collagen zone occurred in all groups, after storing. TBF showed the highest roughness, microhardness, and DC values, and GB showed the lowest. Mild self-etch one-step adhesives (TBF/OUB) showed a higher degree of cure, lower hydrophilicity, and major resistance to degradation of resin-dentin bonds when compared to highly acidic self-etching adhesive (GB).

Effect of adhesive system and application strategy on reduction of dentin permeability

This study evaluated the effect of adhesive systems and application strategies on dentin hydraulic conductance (HC). The buccal enamel was removed from bovine incisors to simulate laminate cavity preparations. After removing the roots and the coronal pulp, the buccal dentin was treated with EDTA solution (0.5 M) for 5 minutes, rinsed, ultrasonicated for 12 minutes and connected to a permeability device. HC of the specimens was measured at 10 psi (n = 5). Permeability was measured before and after bonding procedures using G-Bond (GB), Clearfil Tri-S Bond (CTS), Hybrid Coat (HY), Bond Force (BF), Adper Easy Bond (AEB) Silorane (SI), Clearfil SE Bond (CSE) and Adper Scotchbond Multi-Purpose (SMP) adhesives systems, which were applied following three strategies: 1) according to the manufacturers' instructions; 2) two coats of all-in-one self-etching adhesives (GB, CTS, HY, BF, AEB) or priming step plus two coats of bonding resin for the other systems (SI, CSE and SMP); and 3) a thin layer of a flowable composite applied over one coat of all-in-one self-etching adhesives or primed surface for SI, CSE and SMP adhesives. No significant difference was observed among the application modes concerning their ability to reduce HC. None of the adhesives showed complete sealing (100%) of the bovine tooth dentin. SI exhibited lower HC than SMP, however, they were not significantly different from the other systems. The results suggest that all systems tested result in an HC reduction of more than 90%. The wet bonding technique seemed to be more sensitive for dentin sealing.

Long-term evaluation of water sorption and ultimate tensile strength of HEMA-containing/-free one-step self-etch adhesives

ObjectiveThe objective of this study was to evaluate the water sorption (Wsp) and ultimate tensile strength (UTS) of HEMA-containing/free one-step self-etch adhesives after long-term water-storage. MethodsThree HEMA-containing one-step self-etch adhesives (Bond Force (BF), Clearfil S3 Bond (S3) and OptiBond All-In-One (OP)), and one HEMA-free one-step self-etch adhesive, G Bond (GB) was used. After the solvents of each adhesive were evaporated, polymerised adhesive disks and dumbbell-shaped specimens of thirty-two each were prepared and divided into four groups of 14-, 90-, 180- and 360-day water-storage. After immersion in water for the designated storage periods, the disks were subjected to measurement of Wsp, and the dumbbell-shaped specimens were subjected to measurement of UTS. The data of Wsp and UTS were statistically analysed using a two-way ANOVA and Bonferroni test. ResultsWsp of BF, S3 and OP increased over time, whereas for GB, there were no significant differences in Wsp among all the storage periods. Wsp of GB was lower than those of BF, S3 and OP in each period. The UTS of BF, S3 and OP decreased over time, whereas for GB, there were no significant differences in UTS among all storage periods. The highest UTS was initially seen in BF>GB=S3=OP, and after 360-day water-storage, seen in BF=GB>OP=S3. ConclusionsFor the HEMA-containing adhesives, Wsp increased and UTS decreased over time. On the other hand, for the HEMA-free adhesive, Wsp and UTS did not significantly change even after 360-day water-storage.

다양한 광원으로 중합한 치과용 접착제의 전단강도에 관한 비교 연구

본 연구의 목적은 상업용으로 시판되고 있는 수종의 치과용 접착제를 세대별로 분류하여 서로 다른 광원에 노출 시켜 중합하고 접착면의 전단 강도 측정을 통해 결합강도를 비교함으로써 간접적으로 광원에 따른 접착제의 중합 양상을 알아보고 소아치과 영역에서 가장 권장할만한 치과용 접착제와 광원 종류의 조합을 알아보고자 함이다. 본 연구에서는 최근에 개발된 치과용접착제를 대상으로 다른 유형의 광원으로 중합하였을 때 영구치 상아질에 대한 결합력 비교 평가하여 임상에서 상아질결합제와 광중합 시스템의 적절한 조합을 선택하는데 도움을 주고자 시행하였으며, 실험재료로 Adper Scotchbond Multi-purpose Plus Adhesive (SM; 3M ESPE, USA), Adper Single bond 2 (SB; 3M ESPE, USA), Clearfil SE Bond (SE; Kuraray Medical Inc., Japan), Adper Prompt L-Pop (PL; 3M ESPE, USA), GBond (GB; GC Cooperation Toyko, Japan)을 이용하여 Elipar Free light 2(LED; 3M ESPE, USA), OptiLux 501 (Halogen, Kerr, USA), Flipo (PAC, LOKKI, FRA) 세 가지의 광원으로 중합하고 전단결합강도를 평가한 뒤 다음과 같은 결과를 얻었다. 1. Freelight 2로 중합하였을 때 전단결합강도는 SM이 가장 높았으며(<TEX>$28.22{\pm}5.56$</TEX>), SB(<TEX>$21.68{\pm}7.44$</TEX>), SE(<TEX>$20.13{\pm}9.88$</TEX>), PL(<TEX>$14.18{\pm}5.88$</TEX>), GB(<TEX>$14.30{\pm}6.81$</TEX>) 순이었다. SM은 PL, GB와 유의한 차이가 있었으나 (p<0.05), SB, SE, PL, GB 간에는 차이가 없었다. 2. Optiux 501로 중합하였을 때 전단결합강도는 SM이 가장 높았으며 (<TEX>$22.06{\pm}7.95$</TEX>), PL(<TEX>$12.94{\pm}4.96$</TEX>), SB(<TEX>$12.80{\pm}3.35$</TEX>), SE(<TEX>$12.43{\pm}4.79$</TEX>), GB(<TEX>$10.00{\pm}3.47$</TEX>) 순이었고, SM만 유의한 차이가 있었으나 (p<0.05), 다른 군 간에는 차이가 없었다. 3. Flipo로 중합하였을 때 전단결합강도는 SM이 가장 높았으며 (<TEX>$26.82{\pm}11.16$</TEX>), PL(<TEX>$15.42{\pm}9.35$</TEX>), SB(<TEX>$10.96{\pm}3.74$</TEX>), SE(<TEX>$9.39{\pm}3.74$</TEX>), GB(<TEX>$7.85{\pm}2.22$</TEX>) 순이었다. SM은 SB, SE, GB 군과 유의한 차이가 있었으나 (p<0.05), 다른 군 간에는 차이가 없었다. 4. 광원에 따른 차이는 SB와 GB에서만 유의성이 있었고, 다른 결합제에서는 유의한 차이가 없었다. 광원에 따른 유의성을 나타낸 결합제 중 SB는 Freelight 2가 다른 광원에 비해 유의한 차이를 보였고 OptiLux 501과 Flipo간의 차이가 없었던 반면, GB는 Freelight 2와 Flipo 간에만 유의한 차이를 나타냈다. The objective of this study was to compare the shear bond strengths of five dentin adhesive systems cured with three different light curing sources. Seventy five noncarious permanent teeth were collected and stored in an 0.1% thymol solution at room temperature after extraction. The tested adhesives were: Adper Scotchbond Multi-purpose Plus Adhesive (SM) Adper Single bond 2 (SB), Clearfil SE Bond (SE), Adper Prompt L-Pop (PL), G-Bond (GB). And three light curing unit systems were used: Elipar Free light 2(LED), OptiLux 501 (Halogen), Flipo (PAC). For the shear bonding test, the labial and lingual surfaces of permanent teeth were used. To obtain a flat dentin surface, the labial and lingual surfaces of the teeth were sanded on SiO2 with number 600 grit and then divided into 15 groups of 10 surfaces each. All samples were theromocycled in water <TEX>$5^{\circ}C$</TEX> and <TEX>$55^{\circ}C$</TEX> for 1000 cycles. The results were as follows: 1. When cured with Freelight 2, the shear bond strength of SM was significantly higher than that of PL, GB (p<0.05), whereas no significant difference was found among those of any other bonding agents. 2. When cured with Optilux 501, the shear bond strength of SM was significantly higher than those of any other bonding agents (p<0.05), whereas no singnificant difference was found among those of andy other bonding agents. 3. When cured with Flipo, the shear bond strength of SM was significantly higher than those of SB, SE, GB (p<0.05), whereas no significant differences was found among those of any other bonding agents. 4. For comparison according to three different light cure unit system, except SB and GB, each three dentin bonding agents showed no significant difference. For SB, only Freelight 2 was significantly higher than the others, with no significant difference between Optilux 501 and Flip. For GB, Statistically significant difference was found only between Freelight and Flipo.

Enamel Margin Integrity of Class I One-bottle All-in-one Adhesive-based Restorations

To evaluate marginal adaptation of Class I restorations in enamel using contemporary one-bottle all-in-one adhesives, stressed by thermocycling (TC) and mechanical loading (ML). Ninety-six extracted human molars were prepared (standard Class I cavities: 3 mm deep, 6 mm wide mesio-distally, and 4 mm wide bucco-lingually). Twelve adhesive systems were used: OptiBond FL (OPT), Clearfil SE Bond (CSE) and Adper Prompt L-Pop (PLP) as controls, compared with nine one-bottle all-in-one adhesives - AdheSe One (AHO), Adper Easy Bond (EB), Bond Force (BF), G-Bond (GB), iBond Self Etch (IB), One Coat 7.0 (OC), OptiBond All-in-one (OPA), Clearfil Tri-S-Bond (TSB), Xeno V (XV). All teeth were restored using Filtek Z250 placed in three (one horizontal, two oblique) increments. Enamel margins were evaluated following 21 days of water storage, after thermocycling (2000 cycles: 5°C to 55°C), and after mechanical loading (150,000 cycles, 50 N). After each step, replicas were produced and quantitative SEM margin analysis was performed (200X) using defined criteria. The median values of % "continuous margin" following TC and ML, respectively, were: OPT(98.6/96.2), CSE(95.4/90.9), BF(81.7/68.1), GB(81.1/65.0), OPA(83.0/68.1), OC(64.1/41.3), TSB(59.3/42.2), EB(57.1/42.6), IB(38.4/27.6), PLP(36.6/21.5), XV(45.0/30.0), AHO(17.7/5.4). Statistical evaluation (Kruskal-Wallis test with Bonferroni adjustment, p < 0.05) revealed the following ranking for ML: OPT=CSE>BF=OPA=GB>OC=EB=TSB=XV =IB=PLP>AHO. All one-bottle all-in-one adhesives exhibited statistically significant lower marginal qualities in enamel compared to the etch-and-rinse system OPF and the two-step self-etching system CSE. The results obtained for GB, OPA and BF, however, were better than for the other all-in-one adhesives.

Micromorphological effects and the thickness of the hybrid layer - a comparison of current adhesive systems.

the aim of this study was to evaluate the effect of dental conditioners in terms of dentin micromorphology and the thickness of the hybrid layer obtained by using the self-etching adhesive systems Adhe SE (AD), G Bond (GB), Adper Prompt L Pop (LP) and Tyrian (TY) and the etch-and-rinse Single Bond (SB). dentin sticks from 50 third human molars were obtained by first cutting dentin disks out of crowns; the disks were subsequently sectioned into sticks. The sticks were assigned to experimental groups as follows: G1: phosphoric acid 37%, Single Bond (SB); G2: Adhe SE (AD); G3: G Bond (GB); G4: Adper Prompt L-Pop (LP); G5: Tyrian SPE (TY). Half the samples served to investigate the dentin micromorphology. To this end, the proprietary conditioner of the respective adhesive system was applied to these samples, and conditioner effects were examined with SEM. The other half of the samples was hybridized and restored with composite resin to investigate the thickness of the hybrid layer, which was also evaluated with SEM. Statistical analysis was performed with ANOVA, Tukey's, and the Kruskal-Wallis tests. SEM observation showed significant differences of the hybrid layer thickness. LP presented the highest average thickness, 3.45 microm, while SB presented an average of 2.44 microm and AD an average of 1.43 microm. The averages of TY and SB did not show any statistically significant differences. The adhesive system GB presented the lowest average in hybrid layer, 0.37 microm. The micromorphological evaluation showed that the conditioners commonly removed the smear layer. all the micromorphological alterations and the hybrid layer thickness show that the adhesive systems studied performed distinct actions. Although there is no apparent correlation of the pH of the conditioners with the thickness of the hybrid layer, it is clear that more acidic conditioners promote more severe transformations in the dentin micromorphology.

Effect of repeated use on dentin bond strength of two adhesive systems: All-in-one and one-bottle

To compare the effects of repeated use of two one-bottle adhesives with that of two all- in- one adhesives (with acetone solvent) on bond strength to dentin. A flat dentin surface was prepared on 120 bovine incisors using 600- grit abrasive pape. The teeth were randomly assigned into 12 equal groups. The four adhesive systems [Prime and Bond NT (P&B NT), One-Step Plus (OS), iBond (iB), and G-Bond (GB)] were used at baseline, after the lid of the container had been opened 30 times, and after it had been opened 60 times. Before each use of the adhesives, the lids of the containers were left open for 1 min. The resin composites were applied on the dentin in a cylindrical split mold. After thermocycling, shear bond strength test was performed with a universal testing machine at 1 mm/min. We used Kruskal-Wallis and Dunn tests for statistical analysis. There was no statistically significant difference among bond strength (MPa) of the groups of P&B NT (31.9 +/- 4.6, 31.8 +/- 6.5, 26.1 +/- 6.7) and OS (33.2 +/- 5.1, 30.9 +/- 7, 29.3 +/- 5.9), respectively (P > 0.05). The mean of the bond strength of iB and GB after 60 times (15.3 +/- 4.1 and 12.2 +/- 3.9, respectively) was significantly lower than that of iB and GB at baseline (23.5 +/- 4.8 and 22.2 +/- 4.5, respectively) (P < 0.05). Repeated use (60 times) of the all-in-one adhesive led to a decline in the dentin bond strength. To avoid this problem it would be advisable to have containers with smaller amounts of adhesive or perhaps those with only a singe dose.

Effects of coating root dentin surfaces with adhesive materials

The aim of this study was to evaluate the effects of coating root dentin surfaces with adhesives vis-à-vis the prevention of root dentin demineralization. Root dentin surface was ground with #600 SiC, and then either a single coat of Clearfil SE Bond (SE), Clearfil Tri-S Bond (TS), G-Bond (GB), Hybrid Bond (HB-1), or two coats of HB (HB-2) were applied. Specimens were immersed in an artificial demineralizing solution, then sectioned through the center of the root and polished. Thickness of the coating layer and depth of the demineralized dentin layer were observed under a confocal laser scanning microscope (CLSM). Nanohardness values of the coating layer and underlying dentin were measured using a nanoindentation tester. All obtained data were statistically analyzed. Dentin demineralization was not observed in the surface coating groups with the exception of HB-1, and nanohardness of the underlying dentin was comparable to that of normal dentin. Based on the results obtained, it seemed that coating root dentin surfaces with an adhesive material is a promising good practice to prevent demineralization.

Two-year clinical evaluation of one-step self-etch systems in non-carious cervical lesions

Objectives This randomized controlled clinical trial evaluated the 2-year clinical performance of S 3 Bond (S3) and G-Bond (GB) in 108 non-carious cervical lesions. Methods Twenty-three patients, 12 male and 11 female (mean age: 61.8 years, range: 30–79 years) regularly visiting the Nagasaki University Hospital of Medicine and Dentistry, participated in the study. Each patient received both materials randomly. All restorations (53 restorations for S3 and 55 restorations for GB) were placed by one dentist. The restorations were blindly evaluated by two examiners at baseline, 6 months, 1 and 2 years using modified USPHS criteria. The data were statistically analyzed using the Cochran Q test and Fisher's exact test. Results One restoration of each material was lost during 2 years. The only minor clinical problem was the integrity of the enamel margin. Slight marginal staining occurred adjacent to 11 restorations of both S3 and GB. There was no significant difference in the clinical performance between S3 and GB for each variable. Conclusions Under the protocol used in this study, S3 and GB have demonstrated an acceptable clinical performance up to 2 years.

Cytotoxicity of one‐step dentin‐bonding agents toward dental pulp and odontoblast‐like cells

The purpose of this study was to compare the cytotoxicity of five one-step dentin-bonding agents on human dental pulp and odontoblast-like cells (MDPC-23). Photopolymerized and unpolymerized samples of these dentin-bonding agents were prepared and incubated with dental pulp or MDPC-23 cells. After 24 or 72 h of incubation, the number of unstained cells with trypan blue was counted. The staining of cells with trypan blue stands for a cytotoxicity. The pulp cell and MDPC-23 cytotoxicity of polymerized sample treatment increased in the order of AQ Bond Plus (AQ)<Clearfil Tri-S Bond (TS)=G-bond (GB)<Absolute (AB)<Adper Prompt (AP) for 24 and 72 h. The pulp cell cytotoxicity of unpolymerized sample treatment for 24 h increased in the order of AQ<GB = AB<TS<AP. The MDPC-23 cytotoxicity of unpolymerized sample treatment for 24 h increased in the order of AQ<GB<TS = AB<AP. Whether polymerized or unpolymerized, AQ was the least cytotoxic agent, while AP was the strongest. All polymerized dentin-bonding agents exhibited lower cytotoxicity by 2-65% than their unpolymerized counterparts. The appearance of the cytotoxicity of dentin-bonding agents was time-dependent, and cell viability was lower at 72 h by 2-46% than at 24 h. The cytotoxicity to MDPC-23 cells was about 5-24% higher than that to pulp cells. These results indicate that one-step dentin-bonding agents differ markedly in their cytotoxicity. Differential cytotoxic effects of one-step dentin-bonding agents should be considered during clinical application of operative restoration.

Dentine bonding after CPP-ACP paste treatment with and without conditioning

Objectives To evaluate microshear bond strength (MSBS) to dentine following application of a casein phosphopeptide amorphous calcium phosphate paste (Tooth Mousse (TM)), and the effect of smear layer removal before paste application and preconditioning. Methods Specimens of polished human dentine were divided into two groups: 1, smear layer retained; 2, smear layer removed using 15% EDTA for 90 s. In each group, half the specimens were left untreated and half treated with TM for 60 min daily × 7 days. Each subgroup was divided into three further subgroups for conditioning (Primer only; 30–40% phosphoric acid (PA) + primer; 20% polyacrylic acid (CC) + primer). Two self-etching/priming adhesives (Clearfil SE Bond (CSE) and G-Bond (GB)) were used for bonding resin composite to superficial/deep dentine and after 24 h, stressed in shear until failure. Maximum loads at failure and bond failure modes were recorded. Group means were compared using one-way ANOVA and Tukey’s post hoc test at α = 0.05. Results TM did not significantly affect MSBS in group 1. In group 2, there was a statistically significant increase in MSBS for CSE on deep dentine ( P = 0.002) and a reduction for GB ( P = 0.013) on superficial dentine. PA conditioning did not significantly affect MSBS for CSE and GB while CC significantly reduced MSBS for GB. Conclusions TM application did not reduce MSBS for CSE but significantly reduced MSBS for GB when the smear layer was removed before paste treatment. Preconditioning did not improve or worsen dentine MSBS for CSE or GB with/without TM, except when CC was used with GB.

Tensile Bond Strength of One-step Self-etch Adhesives to Er:YAG Laser-irradiated and Non-irradiated Enamel

This study determined the bond strengths to Er:YAG laser-irradiated and non-irradiated bovine enamel of three one-step self-etch adhesives (AQ Bond Plus (AQP), G-Bond (GB), and Clearfil Tri-S Bond (TS)) and one two-step self-etch adhesive (Clearfil Megabond (MB)). Eighty SiC paper-ground bovine enamel surfaces were used, of which half were laser-irradiated. The enamel surfaces were bonded to a resin composite with each adhesive, and tensile bond strengths were determined after 24 hours. For non-irradiated enamel groups, MB achieved greater bond strength to enamel than GB and TS (p < 0.05), but no significant difference was found between MB and AQP (p > 0.05). For laser-irradiated enamel groups, no significant differences were found among the four adhesives (p > 0.05). Additionally, for each adhesive, no significant differences were found between laser-irradiated and non-irradiated enamel. It was thus concluded that Er: YAG laser irradiation of enamel did not affect the tensile bond strength of one-step and two-step self-etch adhesives.

Technique sensitivity associated with air-drying of HEMA-free, single-bottle, one-step self-etch adhesives

Objectives This study examined the effect of air-drying on bond strength to dentin and nanoleakage in resin–dentin interfaces using HEMA-free one-step self-etch adhesives. Methods Twelve teeth had their occlusal dentin exposed and split in half. In the group of G-BOND (GB), the adhesive was dried gently or vigorously on each slit half tooth, and then light-cured. In the group of the experimental adhesive (EX), three coats of adhesive were dried using a single air-drying process prior to light-curing or dried after each of three coats of adhesive before light-curing. The split specimens were built-up with resin composite and then subjected to microtensile bond strength testing and TEM examination. Results GB showed significantly higher bond strength after vigorous drying than after gentle drying. Three teeth of from EX group showed higher bond strength after triple drying than after single drying, while two teeth showed no significant difference. Droplets were revealed in the adhesive layer after gentle drying with GB, and silver deposits existed along the interfaces in all groups. Significance The bonding quality to dentin may be improved by using an accelerated air-drying technique; although it is impossible to remove intrinsic dentin moisture that is drawn upwards from dentin tubules.