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Microtensile bond strength (μTBS) test was introduced in 1994. Since then, it has been utilized profoundly across many bond strength testing laboratories, making it currently one of the most standard and versatile bond strength test. Although it is a static and strength-based method, together with the morphological and spectroscopic investigations, it has been contributing immensely in the advancement of dentin adhesive systems. μTBS test has a greater discriminative capability than the traditional macro-shear bond test. During the early stage of its development, the authors predicted that this testing method would enable evaluation of the adhesive performances of resins to excavated carious or sclerotic dentin and the regional bond strengths of various portions of the cavity. In addition, they also stated the possibility of comparing the long-term stability of resin adhesion at various portions of the cavity walls on teeth extracted at various times after insertion of bonded restorations. In this review, we discussed the historical background, inception and the application of the μTBS test and proposed directions for further improvement of this testing method. [ABSTRACT FROM AUTHOR]

Abo T, Uno S, Sano H. Comparison of bonding efficacy of an all-in-one adhesive with a self-etching primer system. Eur J Oral Sci 2004; 112: 286–292.© Eur J Oral Sci, 2004 The aim of this study was to compare the bonding efficacy of an all-in-one adhesive with that of a self-etching primer system by measuring microleakage after thermocycling and the microtensile bond strength (μTBS) to enamel and dentin. Circular class V cavities along cement–enamel junctions were prepared in 20 extracted human premolars. Each 10 teeth were bonded with either AD Bond (AD) or Clearfil SE Bond (SE), and filled with a resin composite (Charisma). After thermocycling and staining with 0.5% basic fuchsin, the microleakage at the coronal and apical walls was evaluated using longitudinal sections. In addition 20 premolars were used to measure μTBS at 24 h after bonding for these adhesives to enamel and dentin that corresponded to the coronal and apical walls of the class V cavities. AD showed more microleakage than SE in the coronal walls, but there was less microleakage in the apical walls and no difference in apical leakage between the two adhesives. μTBS (SD) in MPa to enamel and dentin were 25.2 (7.3) and 68.3 (9.4) for AD, and 35.8 (7.4) and 76.4 (7.8) for SE, respectively. AD gave a lower μTBS to enamel than did SE. The results suggested that the poor adaptation at the coronal wall in AD might be caused by the lower bond strength to enamel. [ABSTRACT FROM AUTHOR]

Purpose: To determine the physical properties between enamel and dentin at the dentin-enamel junction (DEJ) region of natural tooth structure. Materials and Methods: Ultimate tensile cohesive strengths of the DEJ region of human and bovine teeth were measured using a microtensile test, and the nanohardness and Young's modulus from deep enamel to superficial dentin of human teeth were measured using a nanoindentation tester. Results: The mean ultimate tensile cohesive strengths of bovine and human DEJ region were 47.7 MPa and 51.5 MPa, respectively. The nanohardness, dynamic hardness and Young's modulus of the DEJ region showed moderate values between those of enamel and dentin. Comparison of the cohesive strength of the human DEJ region with previous results of the bond strength of resin bonding systems indicate that current resin bonding systems might reproduce the biological adhesion of enamel to dentin in terms of the tensile strength. Moreover, the indentation properties of the DEJ region showed higher values than those of the underlying dentin or of resin impregnated dentin. [ABSTRACT FROM AUTHOR]

The removal or modification of smear layers that cover the dentin is critical to allow the penetration of adhesive molecules and to ensure a strong bond between resin and dentin. Aiming to establish a model for clinically-relevant dentin-bond testing, we evaluated the effects of smear layers created by abrasives having similar coarseness (180-grit SiC paper; fine-grit diamond bur) and application modes (single application; double application) on the microtensile bond strengths (µTBS) of two currently available universal adhesives (G-Premio Bond; Scotchbond Universal Adhesive) and a two-step self-etch adhesive (Clearfil Megabond 2). Sixty extracted human third molars were used for the μTBS test. Data were analyzed by three-way ANOVA and Tukey's test (α = 0.05). Fracture modes were determined using stereomicroscopy. An additional 24 third molars were prepared for observation of the resin–dentin interface by TEM and adhesive-smear layer interaction by SEM. μTBS was significantly affected by the adhesives and their application modes (p < 0.001), implying that the double application of universal adhesives should be recommended to improve their performance. The effect of smear layers was not significant (p > 0.05), indicating that 180-grit SiC papers could be used to prepare dentin as a substitute for fine-grit diamond burs for dentin-bond testing in laboratory settings. [ABSTRACT FROM AUTHOR]

The purpose of this study was to determine the bond stability and the change in interfacial ultra-structure of a conventional glass-ionomer cement bonded to dentin, with and without pre-treatment using a polyalkenoic acid conditioner. The occlusal dentin surfaces of six teeth were ground flat. Glass-ionomer cement was bonded to the surfaces either with or without polyalkenoic acid conditioning. The teeth were sectioned into 1-mm2 stick-shaped specimens. The specimens obtained were randomly assigned to two groups with different periods of storage in water: 1 week and 1 year. The micro-tensile bond strength (μTBS) was determined for each storage time. Additional specimens were prepared for Transmission Electron Microscopy (TEM); they were produced with or without prior polyalkenoic acid conditioning in the same way as in the μTBS test. There was no significant difference in μTBS to conditioned dentin and non-conditioned dentin (p > 0.05). The failures appeared to be of a mixed nature, although aging caused more areas of cohesive than adhesive failure in both groups. The TEM observation showed an intermediate layer, a matrix-rich layer and a partially demineralized layer in the polyalkenoic acid conditioned group. Aging did not reduce the bond strength of the conventional glass-ionomer cement to dentin with or without the use of a polyalkenoic acid conditioner. [ABSTRACT FROM AUTHOR]

Objectives To evaluate the influence of different air-blowing durations on the micro-tensile bond strength (μTBS) of five current one-step adhesive systems to dentin. Methods One hundred and five caries-free human molars and five current one-step adhesive systems were used: ABU (All Bond Universal, Bisco, Inc.), CUB (CLEARFIL™ Universal Bond, Kuraray), GPB (G-Premio BOND, GC), OBA (OptiBond All-in-one, Kerr) and SBU (Scotchbond Universal, 3M ESPE). The adhesives were applied to 600 SiC paper-flat dentin surfaces according to each manufacturer’s instructions and were air-dried with standard, oil-free air pressure of 0.25 MPa for either 0 s, 5 s, 15 s or 30 s before light-curing. Bond strength to dentin was determined by using μTBS test after 24 h of water storage. The fracture pattern on the dentin surface was analyzed by SEM. The resin–dentin interface of untested specimens was visualized by panoramic SEM image. Data from μTBS were analyzed using two-way ANOVA (adhesive vs. air-blowing time), and Games-Howell (a = 0.05). Results Two-way ANOVA revealed a significant effect of materials (p = 0.000) and air-blowing time (p = 0.000) on bond strength to dentin. The interaction between factors was also significantly different (p = 0.000). Maximum bond strength for each system were recorded, OBA/15 s (76.34 ± 19.15 MPa), SBU/15 s (75.18 ± 12.83 MPa), CUB/15 s (68.23 ± 16.36 MPa), GPB/30 s (55.82 ± 12.99 MPa) and ABU/15 s (44.75 ± 8.95 MPa). The maximum bond strength of OBA and SUB were significantly higher than that of GPB and ABU (p < 0.05). Significance The bond strength of the current one-step adhesive systems is material-dependent (p = 0.000), and was influenced by air-blowing duration (p = 0.000). For the current one-step adhesive systems, higher bond strengths could be achieved with prolonged air-blowing duration between 15–30 s. [ABSTRACT FROM AUTHOR]

Abstract: Objectives: The objectives of this study were (1) to clarify the relationship between the duration of air-drying of one-step self-etch adhesives (1-SEAs) and the evaporation degree (ED) of solvents, and (2) to evaluate the effect of ED on the ultimate micro-tensile strength (μTS) of the adhesives. Methods: The ED of one HEMA-rich 1-SEA, Clearfil S3 Bond (Kuraray), and two HEMA-free 1-SEAs, iBond (Heraeus-Kulzer) and G-Bond (GC), was determined without air-drying and after, respectively, 5- and 10-s air-drying using a gravimetric method. Next, the μTS of the adhesives at ED equivalent to 0-, 5- and 10-s air-drying was measured. Results: The ED increased with extension of air-drying time. Among the adhesives tested, iBond showed the largest ED, followed by G-Bond and Clearfil S3 Bond in this order. A longer air-drying time for 10-s resulted in a statistically significantly higher μTS for the HEMA-rich Clearfil S3 Bond. The μTS of the latter was higher than that of the other two HEMA-free adhesives for each air-drying time. Significance: Air-drying of 1-SEAs had a significant effect on the degree of solvent evaporation (ED) and also on the mechanical properties (μTS) of the 1-SEAs upon setting. It is therefore beneficial to remove solvents of the 1-SEAs as much as possible by thorough, strong air-drying in order to achieve a strong adhesive layer at the interface. [Copyright &y& Elsevier]

Abstract: Objective: Phase-separation within HEMA-free all-in-one dental adhesives may result in the entrapment of droplets within the adhesive resin. Strongly air-blowing prior to polymerization, can remove most of these droplets. The objective of this study was to evaluate the effect these droplets may have on the resistance of the adhesive–tooth interface to NaOCl degradation. Methods: The micro-tensile bond strength (μTBS) to enamel and dentin was determined when a HEMA-free all-in-one adhesive was applied either following a mild or strong air-blowing technique. The bonds were also exposed to an aqueous sodium hypochlorite (NaOCl) solution for 1h, following a recently introduced methodology to mimic in vivo bond degradation. Results: This study revealed that strong air-blowing of the adhesive only resulted in a significantly higher micro-tensile bond strength (μTBS) to dentin, but not to enamel. Likewise, NaOCl only reduced the μTBS to dentin for both the mild and strong air-blowing technique, but again not the μTBS to enamel. Failure analysis by SEM clearly revealed that strong air-blowing is less effective in droplet removal when the adhesive was applied in small and narrow class-I cavities, as compared to when it was applied to flat surfaces. Conclusions: NaOCl did preferentially dissolve the hybrid layer at dentin, and more for the mild than for the strong air-blowing technique. A strong air-blowing procedure resulted in a more NaOCl-resistant hybrid layer, so that it can be concluded that a HEMA-free one-step adhesive definitely benefits from a strong air-blowing technique. [Copyright &y& Elsevier]

Summary: Purpose: To evaluate the technique sensitivity of four different adhesive systems using different air-blowing pressure. Methods: Four adhesive systems were employed: Clearfil SE Bond [SE] (Kuraray, Japan), G-Bond [GB] (GC Corporation, Japan), Adper Prompt L-Pop [LP] (3M ESPE, USA) and an experimental adhesive, SSB-200 [SSB] (Kuraray, Japan). Twenty-four extracted molars were used. After grinding the coronal enamel surface, the teeth were divided into two equal groups. The first group''s teeth were randomly assigned for bonding with the different adhesives using gentle air-blowing (g). For the teeth of the second group, the four adhesive systems were applied using strong air-blowing (s). After storage overnight in 37°C water, the bonded specimens were sectioned into sticks (1mm×1mm wide), which were subjected to microtensile bond strength testing (μTBS) at a crosshead speed of 1mm/min. The load at failure of each specimen was recorded and the data were analyzed by one-way ANOVA and Tukey HSD tests. The surfaces of the fractured specimens were observed using SEM to determine the failure mode. Results: The results of the μTBS test showed that the highest bond strengths tended to be with SE for both gentle and strong air-blowing, and the significantly lowest for SSB with strong air streaming. Comparing the two techniques, significant differences were noted only for SSB-200 (P<0.05). For each material, the SEM evaluation did not show distinct differences in the nature of the fractures between the two techniques, except for SSB-200. Conclusions: The adhesives tested are not technique sensitive, except SSB-200, with regards to the air-blowing step. [Copyright &y& Elsevier]