Clearfil Tri-S Bond Research Articles

The Effect of Phosphoric Acid Pre-etching Times on Bonding Performance and Surface Free Energy with Single-step Self-etch Adhesives.

The purpose of this study was to evaluate the effect of phosphoric acid pre-etching times on shear bond strength (SBS) and surface free energy (SFE) with single-step self-etch adhesives. The three single-step self-etch adhesives used were: 1) Scotchbond Universal Adhesive (3M ESPE), 2) Clearfil tri-S Bond (Kuraray Noritake Dental), and 3) G-Bond Plus (GC). Two no pre-etching groups, 1) untreated enamel and 2) enamel surfaces after ultrasonic cleaning with distilled water for 30 seconds to remove the smear layer, were prepared. There were four pre-etching groups: 1) enamel surfaces were pre-etched with phosphoric acid (Etchant, 3M ESPE) for 3 seconds, 2) enamel surfaces were pre-etched for 5 seconds, 3) enamel surfaces were pre-etched for 10 seconds, and 4) enamel surfaces were pre-etched for 15 seconds. Resin composite was bonded to the treated enamel surface to determine SBS. The SFEs of treated enamel surfaces were determined by measuring the contact angles of three test liquids. Scanning electron microscopy was used to examine the enamel surfaces and enamel-adhesive interface. The specimens with phosphoric acid pre-etching showed significantly higher SBS and SFEs than the specimens without phosphoric acid pre-etching regardless of the adhesive system used. SBS and SFEs did not increase for phosphoric acid pre-etching times over 3 seconds. There were no significant differences in SBS and SFEs between the specimens with and without a smear layer. The data suggest that phosphoric acid pre-etching of ground enamel improves the bonding performance of single-step self-etch adhesives, but these bonding properties do not increase for phosphoric acid pre-etching times over 3 seconds.

Relationship between thin-film bond strength as measured by a scratch test, and indentation hardness for bonding agents

ObjectivesTo evaluate thin-film bond strength between a bonding agent and human dentin, using a scratch test, and the characteristics and accuracy of measurement. MethodsOne-step bonding agents (BeautiBond; Bond Force; Adper Easy Bond; Clearfil tri-S Bond) and two-step bonding agents (Cleafil SE Bond; FL-Bond II) were investigated in this study. Flat dentin surfaces were prepared for extracted human molars. The dentin surfaces were ground and bonding agents were applied and light cured. The thin-film bond strength test of the specimens was evaluated by the critical load at which the coated bonding agent failed and dentin appeared. The scratch mark sections were then observed under a scanning electron microscope. Indentation hardness was evaluated by the variation in depth under an applied load of 10gf. Data were compared by one-way ANOVA with the Scheffé’s post hoc multiple comparison test (p<0.05). In addition, thin-film bond strength and indentation hardness were analyzed using analysis of correlation and covariance. ResultsThe thin-film bond strength of two-step bonding agents were found to be significantly higher than that of one-step bonding agents with small standard deviations. Scratch marks consistently showed adhesive failure in the vicinity of the bonding agent/dentin interface. The indentation hardness showed a trend that two-step bonding agents have greater hardness than one-step bonding agents. A moderately significant correlation (r2=0.31) was found between thin-film bond strength and indentation hardness. SignificanceThin-film bond strength test is a valid and reliable means of evaluating bond strength in the vicinity of the adhesive interface and is more accurate than other methods currently in use. Further, the thin-film bond strength is influenced by the hardness of the cued bonding agent.

Effects of C-factor on bond strength to floor and wall dentin.

This study evaluated the effect of C-factor on the bond strength of a resin composite to floor and wall dentin using two adhesive systems. Box-form cavities were prepared on human molars, following the walls of half of the cavities were removed to create flat dentin surfaces for bonding. Each specimen was then restored using one of two adhesives (Clearfil SE Bond or Clearfil tri-S Bond) and filled or built up using Z100 resin composite. After light-curing, the specimen was cut perpendicular to the bonded surface parallel to the floor or wall to obtain beams. The micro-tensile bond strength to the flat floor, flat wall, cavity floor, or cavity wall was determined. Resin composite bonded more strongly to the flat wall dentin than to the flat floor dentin, regardless of the adhesive system used. Bonding to the cavity wall was higher affected by C-factor than to the cavity floor.

Interfacial Adaptation of Composite Restorations Before and After Light Curing: Effects of Adhesive and Filling Technique.

To investigate the effects of placement technique and adhesive material on adaptation of composites before and after light curing. Cylindrical cavities (3 mm diameter, 1.7 mm depth) in extracted human molars were restored in 6 groups (n=5) using 2 adhesives--two-step self-etching Clearfil SE Bond 2 (SE2) and all-in-one Clearfil Tri-S Bond Plus (TSP) (Kuraray Noritake Dental)--and 2 composites--Estelite Sigma Quick (ESQ) and Estelite Flow Quick (FLQ) (Tokuyama Dental)--placed with three different techniques: ESQ bulk placed, FLQ lining followed by ESQ and FLQ bulk placed. Specimens were scanned twice using swept-source optical coherence tomography (SS-OCT) before and after photopolymerization of the composite. Gap formation during polymerization or the difference in floor interface (DFI%) and final unsealed interface (USI%) were measured by image coregistration and subtraction on 6 diametrical planes across each scan. Two-way ANOVA suggested that both factors (adhesive and filling technique) and their interaction were significant (p<0.001). SE2 showed significantly lower DFI% than did TSP when the composites were placed in bulk, but no difference was found when flowable lining was applied (p<0.05). Within TSP, all filling techniques were significantly different and the lining group showed the lowest values, followed by ESQ-bulk. Overall, SE2 always showed lower UFI% than did TSP, while there was no difference among different techniques within SE2. SS-OCT is a unique method to observe the pre-existing interfacial defects and gaps developed during polymerization, which were found to depend on both placement technique and applied adhesive.

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.

Effect of thermal aging on microleakage of current flowable composite resins

Background/purposeTo evaluate the microleakage of Class V cavities restored with a new self-adhering resin composite after thermal cycling. Materials and methodsStandardized box-shaped Class V cavities were prepared on the buccal and lingual sides of 75 intact human molars (n = 150). The teeth were randomly divided into five groups of 30 cavities each and restored as follows: GroupVF: Vertise Flow (Kerr Corporation, Orange, CA, USA); Group OVF: OptiBond (Kerr) + Vertise Flow; Group SM: Clearfil SE Bond (Kuraray Medical Inc., Okayama, Japan) + Majesty Flow (Kuraray Medical Inc.); Group TM: Clearfil Tri-S Bond (Kuraray Medical Inc.) + Majesty Flow (Kuraray Medical Inc.); and Group UOA: Uni-etch acid (Bisco Inc., Schaumburg, IL, USA) + One-Step Bond (Bisco Inc.) + Aeliteflo (Bisco Inc.). The restorations were finished with aluminum oxide discs (Sof-Lex, 3M ESPE). The restorations were divided into three subgroups (n = 10) and subjected to 1000, 5000, and 15,000 thermal cycles. The teeth were immersed in 0.5% basic fuchsin solution for 24 hours. The dye penetration was examined under a stereomicroscope and scored. The results were statistically analyzed by Kruskal-Wallis, Mann-Whitney U, and Wilcoxon tests. ResultsThe Mann-Whitney U test revealed that for cementum leakage scores of 1000 cycled groups, Groups VF, UOA, and OVF showed higher microleakage than Groups TM and SM and the difference was statistically significant (P < 0.05). When the composite groups were compared for 5000 and 15,000 thermal cycles, no significant differences were detected for both enamel and cementum microleakage scores (P > 0.05). ConclusionThe sealing ability of the new self-adhering flowable composite is detected as similar to the traditional flowables when subjected to long term thermal aging.

SEM Evaluation of Internal Adaptation of Bases and Liners under Composite Restorations

The aim of this study was to evaluate the interfacial microgaps generating between different materials and between materials and dentin after polymerization of the composite restorations, using SEM. Methods: The materials investigated were a composite, an adhesive, a RMGI, and a calcium hydroxide. Thirty third molars were selected and two circular class V cavities (5 mm × 3 mm) for each tooth were made. The teeth were randomly assigned into six groups and restored with a combination of the materials. The specimens were subjected to thermocycling and each tooth was sectioned mesiodistally in two halves. Each half was sectioned along the longitudinal axis through the center of the restorations to obtain a slice of 2 mm. The specimens were examined under SEM. The interfaces between the liners, the liners and dentin, and between the liners and the composite were examined for microgaps. Results: The results showed that there was not any significant difference in the mean width of microgaps in the interfaces between Dycal-dentin and Vitrebond-dentin (p&gt;0.05). However, the width of microgaps in the interfaces between dentin-Clearfil Tri-S Bond was significantly smaller (p&lt;0.05). The use of Clearfil Tri-S Bond reduced the possibility of microgap formation between the bonded interface and the materials tested.

Can dentin surfaces be bonded safely with total-etch and self-etch systems?

Abstract Objective: To assess and compare the shear bond strengths (SBSs) of orthodontic brackets bonded to enamel and dentin surfaces by using total-etching and 3 different self-etching adhesives. Materials and Methods: A total of 160 extracted mandibular incisors were randomly divided into 4 groups. In Group I, the hard tissue was etched with 37% phosphoric acid; in Group II, Transbond Plus Self Etching Primer (TSEP) system was used; in Group III, Clearfil Tri-S Bond Plus was used; and, in Group IV, AdheSE was used. Each group was divided into 2 subgroups: The enamel surfaces were conditioned in subgroup-A, and the dentin surfaces were conditioned in subgroup-B. The samples were stored in water for 24 h at 37°C and then thermocycled. The SBS in megapascals (MPa) was determined by a shear test with 0.5 mm/min crosshead speed, and failure types were classified with modified adhesive remnant index (ARI) scores. The data were analyzed with two-way analyses of variance, Tukey′s, and Chi-square tests at the 0.05 level. Results: The mean SBS value of subgroup-A in Group I was significantly higher than the mean values in the other groups (P&lt;0.05). There were no significant differences among the SBS values in the other groups (P&gt;0.05). Significant differences were found in the ARI between subgroup-A in Group I and the other groups (P&lt;0.001). Conclusions: When used on the enamel, the self-etch systems did not have bond strengths as high as that in the conventional method. However, the self-etch systems can be used as successfully as the conventional method on dentin surfaces.

Potential smear layer interference with bonding of self-etching adhesives to dentin.

To evaluate the effect of smear-layer interposition on the bonding effectiveness of self-etching adhesives with different etching potential. Bur-cut dentin specimens were obtained from 25 human molars after preparation of the dentin surface with a medium-grit diamond bur (bur-cut). An additional 25 molars were fractured at the midcoronal dentin to create a smear-layer-free surface (smear-free dentin). The prepared teeth were assigned to 5 groups, according to the adhesive to be applied: a strong one-step self-etching adhesive (PLP, Adper Prompt L-Pop, 3M ESPE, pH = 0.8); two ultra-mild one-step self-etching adhesives (C3S, Clearfil Tri-S Bond, Kuraray, pH = 2.7; AEB, Adper Easy Bond, 3M ESPE; pH = 2.7 ); as the self-etching control, a mild two-step self-etching adhesive (CSE, Clearfil SE Bond, Kuraray, pH of primer = 1.9); and as the etch-and-rinse control, a three-step etch-and-rinse adhesive (OFL, Optibond FL, Kerr). After composite buildups were made, all specimens were stored in distilled water (24 h/37°C) prior to microtensile bond strength testing (µTBS). The failure mode was determined with a stereomicroscope at 50X magnification. Representative µTBS specimens were processed for analysis in a Feg-SEM. The Kruskal-Wallis test was performed to determine statistical differences (p < 0.05). Except for the strong one-step self-etching adhesive, all other self-etching adhesives (mild and ultramild) revealed a significantly lower bond strength to bur-cut dentin than to smear-free dentin. The etch-and-rinse adhesive presented the highest µTBS, which was not significantly different when bonded to bur-cut or smear-free dentin. Fracture analysis demonstrated a prevalence of adhesive failures for the self-etching adhesives, while OFL revealed more mixed failures. SEM revealed that smear debris remained part of the adhesive interfacial complex produced by the ultra-mild one-step self-etching adhesive C3S when applied on bur-cut dentin. Smear debris interferes with the interaction of mild and ultra-mild self-etching adhesives with dentin.

Influence of photo-curing distance on bond strength and nanoleakage of self-etching adhesive bonds to enamel and dentin

Objectives. To assess the influence of light-curing unit tip distance on the microtensile bond strength (μTBS) and nanoleakage of self-etching adhesives to enamel and dentin. Materials and methods. Flat buccal surfaces were prepared on 198 bovine incisors. The teeth were randomly assigned into nine groups for μTBS (n = 8) and nanoleakage (n = 3) testing according to the adhesive system (Clearfil Protect Bond, Clearfil Tri-S Bond or One Up Bond F Plus) and distance from the light-curing tip (0, 3 or 6 mm). The bonded samples were tested in tension (0.5 mm/min) and nanoleakage was analyzed using SEM. Results. Clearfil Protect Bond exhibited the highest tensile strength on both enamel and dentin. Leakage was higher in samples exposed at a distance of 6 mm on enamel and 0 mm on dentin. One Up Bond F Plus experienced the greatest amount of nanoleakage on both substrates. Conclusions. Light-curing unit distance did not influence the μTBS of the adhesives, but nanoleakage increased on enamel samples when photoactivation occurred at a distance of 6 mm.

3-year clinical effectiveness of one-step adhesives in non-carious cervical lesions

ObjectivesDespite representing an important component of current dental adhesives, HEMA has been said to negatively influence the long-term stability of adhesion to dentine and enamel. The aim of this randomised clinical trial was to evaluate the 3-year clinical performance of two one-step self-etch adhesives. MethodsThirty patients had 175 non-carious cervical lesions restored with composite (Gradia Direct Anterior, GC) using either the HEMA-rich adhesive Clearfil Tri-S Bond (C3S; Kuraray) or the HEMA-free adhesive G-Bond (GB; GC). The restorations were evaluated by two examiners at baseline, 6, 12, 24 and 36 months regarding retention, caries recurrence, marginal integrity and discoloration and post-operative sensitivity. The data were statistically analysed with GEE and McNemar tests (p<0.05). ResultsThe recall rate at 6 and 12 months was 100% and decreased to 96.7% at 24 and 36 months. At 3 years, the retention rate was 93.8% for C3S and 98.8% for GB (p=0.14). A pairwise comparison showed no significant differences between the two adhesives for all the parameters evaluated, irrespective of the recall (p>0.05). After 3 years, both adhesives presented an increase in the percentage of clinically acceptable marginal discoloration (C3S: 32.9% and GB: 26.8%) normally associated to clinically acceptable marginal defects (C3S: 35.8% and GB: 26.5%). Only 1 dentine margin of a GB restoration presented a severe marginal defect (1.2%) and 1 C3S restoration presented caries recurrence. The overall 3-year clinical success rate was 92.6% for C3S and 97.6% for GB (p=0.16). ConclusionBoth one-step self-etch adhesives presented an equally favourable clinical effectiveness at 3 years. Clinical significanceHEMA is a monomer frequently present in dental adhesives in order to increase their wettability and hydrophilicity. However, this monomer negatively influences hydrolytic stability and durability of the adhesive interface complex. In this 3-year clinical trial no significant difference in bonding effectiveness was noticed between a HEMA-rich and HEMA-free one-step adhesive.

Interfacial Nanoleakage and Bonding of Self-Adhesive Systems Cured with a Modified-Layering Technique to Dentin of Weakened Roots

The purpose of the study was to evaluate the nanoleakage and bond strength of different self adhesive systems cured with a modified-layering technique (MLT) to dentin of weakened roots. Twenty-one maxillary incisors were decoronated and then root canals were instrumented and obturated with the cold lateral compaction technique. Weakened roots were simulated by flaring root canals until only 1 mm dentin thickness remained. Teeth were distributed into three groups. The canals were backfilled with Vertise Flow (VF group), a self-adhering system, following a modified-layering technique using two light-transmitting posts, sizes 6 and 3. DT Light Post size 2 was cemented using the same material. Remaining roots were prepared and cured in the same way as the VF group. However, in the TS/MF group, Clearfil Tri-S Bond (TS) adhesive and Clearfil Majesty Flow (MF) composite were used, while in the ED/PF group, ED primer II (ED)/Panavia F2.0 (PF) were used. After one week of storage, each root was sectioned to obtain six slices (two slices from each root third: coronal, middle and apical) of 0.9 ± 0.1 mm thickness. Interfacial nanoleakage expression was analyzed using a field emission scanning electron microscope (FEG-SEM), and the micro push-out bond strength (μPOBS) was measured at different root regions. Modes of failure were also determined using SEM. Data were statistically analyzed using two-way analysis of variance with repeated measures and Tukey post hoc test (p≤0.05). With MLT, all adhesive systems showed nanoleakage. For μPOBS, there was a statistically significant effect for adhesive systems (p<0.001) but not for root region (p<0.64) or for their interaction (p=0.99). Tukey post hoc test revealed that the bond strength of the VF group was significantly higher than the TS/MF and ED/PF groups for all root regions. All of the tested self-adhesive systems cured using MLT had slight nanoleakage and were not sensitive to root regional differences. Self-adhering systems had higher bond strength than self-etch adhesives.

Effect of solvent evaporation strategies on regional bond strength of one‐step self‐etch adhesives to root canal dentine

To evaluate the efficacy of different solvent evaporation strategies on bonding of one-step self-etch adhesives to root canal dentine. Two dual-cure resin core systems (Clearfil DC Bond/Clearfil DC Core Automix and Clearfil Tri-S Bond Plus/Clearfil DC Core Plus; Kuraray Noritake Dental, Tokyo, Japan) were equally applied in 24 post spaces from extracted human mandibular premolars. After the adhesive application, specimens were randomly assigned into four water/solvent evaporation strategies as follows (I) insertion of absorbent paper point for 10s: P, (II) 10s air-blowing: A, (III) as (II) followed by insertion of absorbent paper point: AP, (IV) as (III) followed by 10s additional air-blowing: APA. Then, the adhesives were light cured, and resin core materials were placed into the post space, followed by light curing for 60s. After water storage for 24h, 0.6×0.6mm-thick beams were prepared to measure the regional μTBS. The mode of failure was also observed. The μTBS values were statistically analysed using three-way anova and Duncan HSD test (α=0.05). In the coronal region, there were no significant differences in μTBS between each evaporation strategy (P>0.05), except P group. However, in the apical region, APA and AP groups significantly increased in μTBS compared with A and P groups (P<0.05). Only in the APA group of Clearfil Tri-S Bond Plus/Clearfil DC Core Plus, was there no significant difference in μTBS between the coronal and apical regions (P>0.05). The use of paper points with additional air-blowing for removing excessive adhesive and evaporating residual water/solvent would be effective in producing higher bond strength for the tested one-step self-etch adhesives and fewer blister formations in deeper regions of the post space.

Improved long-term bonding performance of an experimental all-in-one adhesive

The aim of this study was to determine the performance of an experimental all-in-one adhesive. The adhesive, named MTB-200 (Kuraray Medical), contained components to enhance both bond strength and hydrophobicity. The performance of the adhesive was compared with that of CLEARFIL TRI-S BOND (Kuraray Medical) and BeautiBond (SHOFU) using micro-tensile bond strength test and ultramicroscopic observations. The study revealed that the new adhesive had the highest tensile strength value among the three adhesives over time, although transmission electron microscopic images showed the phenomenon of filler de-bonding in the adhesive resin layer. In spite of modification in the experimental adhesive, the adhesive was suspected to degrade bond performance. However, revision of the composition of adhesives would be one of the solutions to enhance durability of interface.

Analysis of the interfacial micromorphology and bond strength of adhesive systems to Er:YAG laser-irradiated dentin

This study evaluated the effects of different parameters of dentin irradiation with erbium -doped yttrium aluminum garnet (Er:YAG) laser on bond strength to dentin and analyzed the ultramorphological characteristics of resin-laser-irradiated dentin interfaces using a transmission electron microscope (TEM). Dentin surfaces were abraded with SiC paper (600 grit) or Er:YAG laser-irradiated (120/4, 140/6, 180/4, or 200/6mJ/Hz). Three adhesive systems were tested: Single Bond Plus (3M ESPE), Clearfil Protect Bond (Kuraray Med.), and Clearfil Tri-S Bond (Kuraray Med.). Treatments were performed over flat dentin surfaces of human third molars. Specimens were stored in distilled water for 1week or 6months and prepared for a microtensile bond strength test and interfacial ultrastructure for analysis. Microtensile bond strength data (n = 5) were analyzed with three-way analysis of variance. Irradiation with Er:YAG laser did not reduce the bond strength values for self-etching adhesives even after 6months of water storage. The hybrid layer formation was observed only when the adhesives were applied to non-irradiated dentin (control group). Nanoleakage occurred in all resin-dentin interfaces using Single Bond Plus for both periods. Nanoleakage pattern and bond strength of self-etching adhesives to dentin were less affected by Er:YAG laser irradiation and by the 6-month storage in water than was those of the etch-and-rinse adhesive. TEM analysis revealed no hybridization when dentin was laser-irradiated. Minimally invasive caries removal has been proposed. Nevertheless, bonding mechanisms to lased dentin are not entirely described. Knowing the interaction between the treated dentin and bonding agents and its behavior over time is of utmost importance for new technologies. Regarding that, two-bottle self-etching adhesive system provided a more consistent evidence of its better behavior when bonding to lased substrate.

Shear and micro-shear bond strengths of four self-etching adhesives measured immediately and 24 hours after application

This study measured the immediate and 24 h shear (SBS) and micro-shear bond strengths (MSBS) to dentin of four self-etching adhesives. A resin composite was bonded using each adhesive to the area of 5-mm diameter for SBS test or 0.75-mm diameter for MSBS test of flat bovine dentin. The bond strengths of all adhesives at 10 min were lower than at 24 h for both tests. The mean SBS (MPa, 10 min, 24 h) were similar in ranking order at both time periods that is: Clearfil SE Bond (21.2, 25.3) >Clearfil TriS Bond (12.7, 19.5)=i Bond (11.7, 19.5)=G Bond (11.1, 16.6). For the MSBS test, G Bond provided equivalent mean bond strength (35.0) to Clearfil SE Bond (36.9) and higher than the other adhesives at 24 h [i Bond (26.3), Clearfil TriS Bond (28.5)]. In conclusion, the MSBS test was slightly more discriminating than the SBS test.

Morphological categorization of acid-base resistant zones with self-etching primer adhesive systems

This study investigated the influence of the composition of self-etching primer adhesive systems on the morphology of acid-base resistant zones (ABRZs). One-step self-etching primer systems (Clearfil Tri-S Bond, G-Bond, and One-Up Bond F Plus) and two-step self-etching primer systems (Clearfil SE Bond, Clearfil Protect Bond, UniFil Bond, and Mac Bond II) were used in this study. Each adhesive was applied on prepared dentin disk surfaces, and a resin composite was placed between two dentin disks. All resin-bonded specimens were subjected to acid-base challenge. Observation under a scanning electron microscope (SEM) revealed the creation of an ABRZ adjacent to the hybrid layer for all the self-etch primer adhesive systems, even when non-fluoride releasing adhesives were used. The presence of fluoride in two-step self-etching adhesive significantly increased the thickness of ABRZ created. Results suggested that an ABRZ was created with the use of self-etching primer adhesive systems, but its morphology differed between one-and two-step self-etching primer adhesive systems and was influenced by fluoride release activity.

Effect of remaining dentin thickness on bond strength of various adhesive systems to dentin

The aim of this study was to evaluate the effect of remaining dentin thickness (RDT) on resin composite bond strength to dentin surfaces when using various adhesive systems. One of three adhesives, Clearfil SE Bond, Single Bond or Clearfil Tri-S Bond, followed by Z100 resin composite were built up on flat dentin surfaces of human molars. The teeth were sectioned obtaining beams with crosssectional areas of approximately 1 mm(2). RDT was measured and microtensile bond strength was determined. Resulting data were categorized into four groups: RDT<2 mm; 2≤RDT<3 mm; 3≤RDT<4 mm; RDT≥4 mm. Clearfil SE Bond showed a correlation between µTBS and RDT. Single Bond showed no significant difference in µTBS for any RDT. The bond strength of resin composite to the different RDT flat dentin surfaces was affected by the adhesive system used.

Non-invasive quantification of resin–dentin interfacial gaps using optical coherence tomography: Validation against confocal microscopy

Objectives Regardless of the cause, gap formation at the tooth–restoration interface may result in treatment failure; non-destructive assessment and monitoring of these defects are important. The aim of this in vitro study is to assess the tooth–restoration interface using a non-invasive technique; swept source optical coherence tomography (SS-OCT) and to confirm the findings with confocal laser scanning microscope (CLSM). Methods Cylindrical class-I cavities (3 mm in diameter and 1.5 mm in depth) were prepared in the occlusal surface of human premolars. Each cavity was restored using an all-in-one adhesive system (Clearfil Tri-S Bond) and one of the three types of composites placed in bulk; Majesty Posterior, AP-X and Majesty LV (all by Kuraray Medical, Japan). Ten serial cross-sectional images of the whole restored cavity were obtained by SS-OCT at 1319 nm center wave length, to which locations the specimens were later trimmed, polished and observed under CLSM. An image analysis software was used to detect significant peaks in the signal intensity at the resin–dentin interface of the cavity floor. The presence and dimensions of gaps at the interface were also confirmed by CLSM. Results Increased SS-OCT signal intensity along the interface corresponded well to the interfacial gaps detected by CLSM. The actual gap size detected ranged from 26 μm to 1.9 mm in length, and the universal composite APX showed lowest interfacial gaps. Conclusion SS-OCT imaging technology can be used to non-invasively detect and quantify micrometer gaps at the bottom of composite restorations, and potentially become a monitoring tool for composite restorations both in the laboratory research, and in the clinics.

Effect of Reacted Acidic Monomer with Calcium on Bonding Performance

We determined the number of reacted and unreacted 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP) molecules with calcium during the demineralization process of hydroxyapatite or dentin by 10-MDP-based one-step (Clearfil Tri-S Bond, TS) or two-step self-etch adhesive (Clearfil SE Bond Primer, SE). We then examined the effects of the number of reacted and/or unreacted 10-MDP molecules on the initial bond strength and bond durability of the resultant adhesive layer. The null hypotheses were that (1) the etching efficacy of tooth apatite by 10-MDP used in TS was the same as that in SE, and (2) the unreacted 10-MDP polymer included within the adhesive layer does not affect bond durability. Addition of hydroxyapatite or dentin to the TS and SE resulted in decreases in the NMR peak intensities for 10-MDP. The peak intensity for 10-MDP showed a greater reduction in SE than in TS, consistent with the observation that SE provided significantly higher initial mean bond strengths than TS. Further, the unreacted 10-MDP polymer within the adhesive layer did not decrease the mean bond strength, despite the application of 20,000x thermo-cycling.