The Journal of Adhesive Dentistry, 02/2010

With the introduction of the Er:YAG laser, it has become possible to remove enamel and dentin more effectively and efficiently than with other lasers. Thermal damage is reduced, especially in conjunction with water spray. Since FDA (Federal Drug Administration) approval of the Er:YAG laser in 1997 - for caries removal, cavity preparation and conditioning of tooth substance - there have been many reports on the use of this technique in combination with composite resins. Moreover, cavity pretreatment with Er:YAG laser (laser etching) has been proposed as an alternative to acid etching of enamel and dentin. Reports evaluating the adhesion of glass-ionomer cements to Er:YAG-lased tooth substance are scarce. This article reviews the literature regarding adhesion and sealing efficacy using different (pre)treatment protocols in association with Er:YAG laser preparation. Recent research has shown that lasing of enamel and dentin may result in surface and subsurface alterations that have negative effects on both adhesion and seal. It is concluded that at present, it is advisable to respect the conventional pretreatment procedures as needed for the respective adhesive materials. Although the majority of present day reports show that microleakage and bond strength are negatively influenced by laser (pre)treatment (compared with conventional preparation), there is ongoing discussion of how adhesion is best achieved on Er:YAG-lased surfaces. Keywords: resin composite, glass ionomer, microleakage, bond strength, etching, conditioner

Purpose: To determine the in vitro dentinal fluid movement produced by various osmotic stimuli, and evaluate fluid movement across human dentin in response to the application of various osmotic stimuli before and after the application of self-etching adhesive (Clearfil S3 Bond). Materials and Methods: The experiments were carried out on 10 extracted premolars. Each tooth was cut transversely below to the cementoenamel junction with a diamond disk and water coolant. Dentin was exposed at the tip of the buccal cusp by cutting a cavity and was etched with acid. The osmotic stimuli were solutions of saturated CaCl2, sugar syrup, chocolate, and sweet Thai dessert, used as osmotic test solutions, randomly applied to dentin. The fluid flow through dentin obtained after 15 s of application of each osmotic stimulus was measured before and after bonding with Clearfil S3 Bond single-dose. Results: Before bonding procedures, CaCl2 produced peak rates of fluid flow that were significantly higher (p 0.001), when compared with normal saline, sugar syrup, chocolate, and sweet Thai dessert. During the applications of all osmotic stimuli, the amount of fluid movement across resin-bonded dentin was significantly lower than that without adhesives. There were no significant differences of fluid shifts across resin-bonded dentin obtained during the application of any osmotic stimuli. Conclusion: It appears that different osmotic stimuli produced different rates of outward fluid flow through dentin. Clearfil S3 Bond produced similar significant reductions of fluid movement in response to osmotic stimulation, irrespective of the chemical composition, or the osmotic pressure of stimuli. Keywords: osmotic stimuli, fluid flow through dentin, self-etching adhesive, dentin permeability, human teeth

Purpose: To evaluate the effect of additional acid etching on the microtensile bond strength (µTBS) and Weibull modulus (m) of two adhesive systems applied to caries-affected dentin. Materials and Methods: Ninety human molars with coronal carious lesions were sectioned to produce flat coronal surfaces containing caries-affected (CAD) and sound dentin (SD). The teeth were allocated to 6 groups: SB-CT: Control - Single Bond applied according to the manufacturer's instructions; SB+15: Single Bond with additional 35% phosphoric acid etching for 15 s; SB+30: Single Bond with additional etching for 30 s; CF-CT: Control - Clearfil SE Bond applied according to the manufacturer's instructions; CF+15: Clearfil SE Bond with additional 35% phosphoric acid etching for 15 s; CF+30: Clearfil SE Bond with additional etching for 30 s. Composite crowns were incrementally built up. The teeth were sectioned after 24 h in order to produce 2 to 3 slices involving each dentin substrate. The slices were trimmed into hourglass-shaped specimens (n = 30) and tested in tension at a crosshead speed of 1 mm/min. Data were analyzed by three-way ANOVA, Tukey's test (p 0.05) and Weibull statistics. Results: The µTBS to CAD was lower than to SD, except for SB+30. The additional etching increased the µTBS to CAD. The µTBS to SD increased with CF, but decreased with SB. CAD produced lower values of m with both adhesive systems. SB resulted in lower m in sound dentin than CF. The additional etching did not affect the m. Conclusion: The additional etching increases the µTBS to CAD, but not enough to reach the µTBS values obtained in SD. The structural reliability of the bond to CAD is not affected by the additional etching. Keywords: dental adhesive, demineralized dentin, microtensile bond strength test, resin-dentin interface, Weibull analysis

Purpose: To determine the effects of thermocycling on shear bond strengths (SBSs) of a self-etching primer (SEP) after 10,000 and 20,000 thermal cycles. The tested hypothesis was that 10,000 and 20,000 thermal cycles would affect the bond strength of metal brackets bonded to enamel with the self-etching primer. Materials and Methods: Brackets were bonded to bovine incisors with two etching protocols. In group CM (conventional method), teeth were etched with 37% phosphoric acid for 30 s. In group SEP, a self-etching primer (Transbond Plus, 3M Unitek) was applied. Brackets were bonded with light-curing adhesive (Transbond XT, 3M Unitek). The SBSs were determined after water storage at 37°C for 24 h, after 10,000 and 20,000 cycles of thermocycling. Results: For both groups (CM and SEP), SBSs decreased with 10,000 and 20,000 thermal cycles. These decreased SBSs were significantly different from the values obtained with no thermocycling. Highest SBSs were observed with no thermocycling for groups CM and SEP (18.6 and 18.0 MPa, respectively). These values were not statistically different from each other. Lowest SBSs were obtained with 10,000 and 20,000 thermal cycles for group SEP (14.2 and 14.7 MPa, respectively). These values were significantly different from all other SBSs. Conclusion: This study indicates that the SEP (Transbond Plus) provides clinically acceptable bond strength values compared with the conventional method after 10,000 and 20,000 thermal cycles. Keywords: self-etching primer, thermocycling, bond strength

Purpose: The aim of the present paper was to determine the effect of different types of ionizing radiation on the bond strength of three different dentin adhesive systems. Materials and Methods: One hundred twenty specimens of 60 human teeth (protocol number: 032/2007) sectioned mesiodistally were divided into 3 groups according to the adhesives systems used: SB (Adper Single Bond Plus), CB (Clearfil SE Bond) and AP (Adper Prompt Self-Etch). The adhesives were applied on dentin and photo-activated using LED (Lec 1000, MMoptics, 1000 mW/cm2). Customized elastomer molds (0.5 mm thickness) with three orifices of 1.2 mm diameter were placed onto the bonding areas and filled with composite resin (Filtek Z-250), which was photoactivated for 20 s. Each group was subdivided into 4 subgroups for application of the different types of ionizing radiation: ultraviolet radiation (UV), diagnostic x-ray radiation (DX), therapeutic x-ray radiation (TX) and without irradiation (control group, CG). Microshear tests were carried out (Instron, model 4411), and afterwards the modes of failure were evaluated by optical and scanning electron microscope and classified using 5 scores: adhesive failure, mixed failures with 3 significance levels, and cohesive failure. The results of the shear bond strength test were submitted to ANOVA with Tukey's test and Dunnett's test, and the data from the failure pattern evaluation were analyzed with the Mann Whitney test (p = 0.05). Results: No change in bond strength of CB and AP was observed after application of the different radiation types, only SB showed increase in bond strength after UV (p = 0.0267) irradiation. The UV also changed the failure patterns of SB (p = 0.0001). Conclusion: The radio-induced changes did not cause degradation of the restorations, which means that they can be exposed to these types of ionizing radiation without weakening the bond strength. Keywords: adhesion, dentin, dentin adhesives, irradiation, degradation

Purpose: To determine the shear bond strength and adhesive remnant index of orthodontic molar bands cemented with four different adhesives. Materials and Methods: Eighty extracted human third molars were embedded in resin blocks and randomly assigned to one of four groups. Four different band cements were investigated: Ormco OptiBand, Dentaurum GlasTec, GC Fuji Ortho Band Paste Pak, and Unitek Multi-Cure Glass Ionomer Orthodontic Band Cement. Bands were cemented on the molar crowns, and tensile loads were applied to measure the retentive strength. One-way ANOVA was performed for the retentive strength, and the Scheffé multiple comparison test was applied as a post-hoc test. The Fisher exact test was used to determine significant differences in the ARI scores. Results: The mean tensile bond strength of GC Fuji Ortho Paste Pak was significantly higher than those of all the other groups tested. No statistically significant differences were found among the other three groups. Conclusion: Among the adhesives investigated in the present study, Fuji Ortho Paste Pak resin-modified glassionomer cement provided the highest tensile bond strength values. Keywords: shear bond strength, retentive strength, orthodontic cement, orthodontic band, ARI score

Purpose: The aim of this study was to evaluate the compatibility between five self-etching bonding systems (SEBSs) and two resin luting cements (RLCs) assessed by use of an in vitro dentin shear bond test. Materials and Methods: The selected RLCs were: Variolink II in a dual-cure mode and Multilink in a self-cure mode. The SEBSs combined with the RLCs were: two one-step SEBSs (One Up Bond F and Xeno III) and three two-step SEBSs (Clearfil SE Bond, Unifil Bond, and Xeno III primer coupled with Clearfil SE Bond bonding resin as an experimental combination). One hundred fifty human molars were divided into ten groups of fifteen samples each. The samples were tested in shear after seven days of storage at 100% RH and 37°C. After each test, the failure mode was recorded. Results and conclusions: Significant differences in shear bond strength (SBS) were observed according to both the curing mode of the RLC and the adhesive. The one-step systems Xeno III and One Up Bond F revealed a total incompatibility when bonded with the chemical-curing RLC. Conversely, the two-step SEBSs were compatible with chemical and dual-curing RLC. Failure modes and shear values were in good agreement. A positive correlation was found between the pH of the tested adhesive solutions or resins and the SBS data. Keywords: resin luting cement, self-etching bonding system, shear bond strength, incompatibility

Purpose: The purpose of the study was to evaluate the bond strength and durability of a so-called self-adhesive resin luting cement to human dentin. In addition, the influence of a dentin adhesive system on the bond strength was tested. Materials and Methods: Forty-eight dentin disks from human teeth were divided into two groups of 24 specimens. One group was bonded to composite resin tubes with the self-adhesive luting cement (RelyX Unicem Aplicap, 3M ESPE), in the other group the dentin surfaces were conditioned with a three-step dentin adhesive system (OptiBond FL, Kerr) prior to bonding with the same cement. Three subgroups of eight specimens each were tested for tensile bond strength following storage in 37°C tap water for either 3 days or for 150 days with an additional 37,500 thermal cycles either between 20°C and 40°C ("soft TC") or between 5°C and 55°C ("hard TC"). Statistical analyses were performed with the Shapiro-Wilk test, Levene's test, two-way analysis of variance (ANOVA) followed by multiple comparisons with the Scheffé test. Results: Without the dentin adhesive, the mean tensile bond strengths after 3 days were 7.1 ± 3.8 MPa; after 150 days/"soft TC" 6.8 ± 3.6; and after 150 days/"hard TC" 5.3 ± 4.5 MPa. With the dentin adhesive, the mean bond strengths after 3 days were 16.5 ± 5.5 MPa; after 150 days/"soft TC" 13.1 ± 3.9 MPa; and after 150 days/"hard TC" 10.1 ± 5.2 MPa. Conclusion: Regardless of storage conditions, the use of a dentin adhesive increased the tensile bond strength of a self-adhesive resin luting cement significantly in comparison to the use of the luting cement without adhesive. Keywords: tensile bond strength, RelyX Unicem, self-adhesive resin, dentin bonding

Purpose: The aim of this prospective randomized controlled clinical trial was to evaluate the 2-year clinical performance of a self-adhesive resin cement, RelyX Unicem (3M ESPE), used for cementation of ceramic inlays. In addition, the influence of selectively acid etching enamel prior to luting on marginal integrity, inlay integrity, tooth integrity, sensitivity, and complications of the restored teeth was assessed. The hypothesis tested was that there was no significant difference in these criteria between restorations with (Etch) or without prior enamel acid etching (Non-etch). Materials and Methods: Sixty-two IPS Empress 2 inlays/onlays were placed in 31 patients by two experienced clinicians. The restorations were luted with RelyX Unicem with (=experimental group; Etch) or without (=control group; Non-etch) prior enamel etching with phosphoric acid. At baseline, 6 months, 1 year and 2 years after placement, the restorations were assessed by two calibrated investigators using modified USPHS criteria. Results: The recall rate at 24 months was 96.6%. Two restorations were clinically unacceptable due to loss of retention, leading to a survival rate of 96.6% (Kaplan-Meier). No significant difference was noted between the experimental group and the control group regarding marginal integrity, inlay integrity, tooth integrity, complications and sensitivity (McNemar, p > 0.05). An obvious deterioration in marginal adaptation was observed after 24 months as only 21.7% (Etch = 23.4%; Non-etch = 20%) of the restorations exhibited an excellent marginal adaptation compared to 70.7% (Etch = 75%; Non-etch = 66.7%) at baseline. In 74.9% of the restorations, small, still clinically acceptable marginal deficiencies were observed (Etch = 76.6%; Non-etch = 73.2%). Conclusion: The self-adhesive resin cement RelyX Unicem showed acceptable clinical behavior after two years of clinical service. Selective enamel etching prior to luting had no significant influence on marginal integrity, inlay integrity, tooth integrity, sensitivity or complications of the restored teeth after 24 months. Longer term evaluation is needed to confirm this finding. Keywords: glass ceramics, adhesive inlays, luting composite, self-adhesive, clinical trial