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We sought to compare the bond strength of resin cement on moist dentin to that on dry dentin, and determine the relationship between the bond strength and flexural strength of resin cement. The water content of the moist and dry dentins was estimated using infrared spectroscopy. Four adhesive and three self-adhesive resin cements were used. At three times of immediately, after one-day storage, and after 20,000 thermocycles (TC 20k), the shear bond strengths were measured. For all resin cements, both the shear bond strength and the flexural strength were the lowest immediately after setting; however, after one day of water storage or TC 20k, these resin cements had the highest values. Regardless of the condition of the dentin surface upon shear bond strength, the flexural strength of each resin cement was correlated with the shear bond strength of the dentin surface.

Resin bonding to zirconia ceramics is difficult to achieve using the standard methods for conventional silica-based dental ceramics, which employ silane coupling monomers as primers. The hypothesis in this study was that a silane coupling oligomer -a condensed product of silane coupling monomers- would be a more suitable primer for zirconia. To prove this hypothesis, the shear bond strengths between a composite resin and zirconia were compared after applying either a silane coupling monomer or oligomer. The shear bond strength increased after applying a non-activated ethanol solution of the silane coupling oligomer compared with that achieved when applying the monomer. Thermal treatment of the zirconia at 110°C after application of the silane coupling agents was essential to improve the shear bond strength between the composite resin cement and zirconia.

Objectives: Dental ceramic surfaces are modified with silane coupling agents, such as γ-methacryloxypropyl trimethoxy silane (γ-MPTS), to improve bond strength. For bonding between lithium disilicate glass ceramic and resin cement, the objective was to investigate if 8-methacryloxyoctyl trimethoxy silane (8-MOTS) could yield a similar performance as the widely used γ-MPTS., Methods: One hundred and ten lithium disilicate glass ceramic specimens were randomly divided into 11 groups (n=10) according to pretreatment regime. All specimens were pretreated with a different solution composed of one or a combination of these agents: 10 or 20wt% silane coupling agent of γ-MPTS or 8-MOTS, followed by a hydrolysis solution of acetic acid or 10-methacryloyloxydecyl dihydrogen phosphate (10-MDP). Each pretreated surface was luted to a stainless steel rod of 3.6mm diameter and 2.0mm height with resin cement. Shear bond strength between ceramic and cement was measured after 24-h storage in 37°C distilled water., Results: 8-MOTS produced the same bonding performance as γ-MPTS. Both silane coupling agents significantly increased the bond strength of resin cement, depending on their concentration. When activated by 10-MDP hydrolysis solution, 20wt% concentration produced the highest values (γ-MPTS: 24.9±5.1MPa; 8-MOTS: 24.6±7.4MPa). Hydrolysis with acetic acid produced lower bond strengths than with 10-MDP., Significance: Silane coupling pretreatment with 8-MOTS increased the initial bond strength between lithium disilicate glass ceramic and resin cement, rendering the same bonding effect as the conventional γ-MPTS., (Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

Objective: For bonding indirect restorations, some 'universal' adhesives incorporate a silane coupling agent to chemically bond to glass-rich ceramics so that a separate ceramic primer is claimed to be no longer needed. With this work, we investigated the effectiveness/stability of the silane coupling function of the silanecontaining experimentally prepared adhesives and Scotchbond Universal (3MESPE)., Methods and Materials: Experimental adhesives consisted of Scotchbond Universal and the silane-free Clearfil S3 ND Quick (Kuraray Noritake) mixed with Clearfil Porcelain Bond Activator (Kuraray Noritake) and the two adhesives to which γ-methacryloxypropyltrimethoxysilane (γ-MPTS) was added. Shear bond strength was measured onto silica-glass plates; the adhesive formulations were analyzed using fourier transform infrared spectroscopy (FTIR) and 13C nuclear magnetic resonance (NMR). In addition, shear bond strength onto CAD-CAM composite blocks was measured without and after thermo-cycling ageing., Results: A significantly higher bond strength was recorded when Clearfil Porcelain Bond Activator was freshly mixed with the adhesive. Likewise, the experimental adhesives, to which γ-MPTS was added, revealed a significantly higher bond strength, but only when the adhesive was applied immediately after mixing; delayed application resulted in a significantly lower bond strength. FTIR and (13)C NMR revealed hydrolysis and dehydration condensation to progress with the time after γ-MPTS was mixed with the two adhesives. After thermo-cycling, the bond strength onto CAD-CAM composite blocks remained stable only for the two adhesives with which Clearfil Porcelain Bond Activator was mixed., Significance: Only the silane coupling effect of freshly prepared silanecontaining adhesives was effective. Clinically, the use of a separate silane primer or silane freshly mixed with the adhesive remains recommended to bond glass-rich ceramics., (Copyright © 2016 The Academy of Dental Materials. Published by Elsevier Ltd. All rights reserved.)

The purpose of this study was to evaluate how ultrasonic cleaning of silica-coated zirconia surfaces would influence the latter's bond strength to resin luting material. Forty zirconia specimens were divided into four groups: one air abrasion group and three silica-coated groups. Silica-coated specimens were cleaned with distilled water using an ultrasonic cleaner after tribochemical silica coating and then divided into three groups according to cleaning durations: 1 minute, 5 minutes, or without cleaning. Following which, resin luting material was polymerized against the specimens. After storage in water for 24 hours, the specimens were subjected to shear bond strength test. Shear bond strength of silica-coated group without cleaning was significantly higher than the other three groups, but there were no statistically significant differences among the three latter groups. SEM images suggested visible differences among the treatment methods. With EDXS analysis, it was revealed that ultrasonic cleaning decreased the silica content on the treated surfaces. Therefore, results showed that ultrasonic cleaning of tribochemically silica-coated zirconia surfaces decreased the adhesion efficacy to resin luting material.

Objectives: The aims of this investigation were to clarify the effects of 24h water-storage and finishing time on mechanical properties and marginal adaptation to a Class V cavity of eight modern flowable resin-composites., Methods: Eight flowable composites, plus two controls (one microfilled and one hybrid composite), were investigated with specimen sub-groups (n = 10) for each property measured. The principal series of experiments was conducted in model Class V cavities with interfacial polishing either immediately (3 min) after setting or after 24 h water-storage. After the finishing procedure, each tooth was sectioned in a buccolingual direction through the center of the restoration, and the presence or absence of marginal-gaps was measured (and then summed for each cavity) at 14 points (each 0.5 mm apart) along the cavity restoration interface (n = 10 per group; total points measured = 140). The shear bond-strengths to enamel and to dentin, and flexural strengths and moduli data were also measured at 3 min and after 24 h water-storage., Results: For all flowable composites, polished immediately after setting, 14-30 summed gaps were observed (controls: 64 and 42). For specimens polished after 24 h, a significantly (p < 0.05) reduced number of 8-17 summed gaps occurred for only 3 flowable composites; whereas for 5 flowable composites there were non-significantly-different (p > 0.05) numbers (11-17) of summed gaps (controls: 28 and 22). After 24h storage, shear bond-strengths to enamel and to dentin, flexural strengths and moduli increased highly significantly (p < 0.001) for all materials, except Silux Plus., Significance: A post-cure interval of 24 h resulted in enhanced mechanical and adhesive properties of flowable dental composites. In a minority of cases there was also a reduced incidence of marginal-gap formation. However the latter effect may be partly attributed to 24 h delayed polishing, even though such a delay is not usual clinical practice.

Despite progress in the development of denture base resin and artificial tooth materials, dental clinics are still plagued with artificial teeth falling off the denture base--due to poor bond strength--after denture delivery. Against this background, this study sought to examine the effect and durability of an adhesive primer developed exclusively for heat-curing resin on the adhesive strength of heat-curing denture base acrylic resin to plastic artificial tooth. Test specimens were divided into four groups according to the treatment method of the artificial tooth's test bonding surface: air abrasion, adhesive primer application, adhesive primer application after air abrasion, and pretreatment only (control). After heat curing of acrylic resin onto the bonding surface, shear test was performed for two storage periods: 24-hour versus 100-day water storage. From the results obtained, it was revealed that the evaluated adhesive primer was significantly effective in increasing adhesive strength between artificial tooth and acrylic resin, although specimens were stored in water for 100 days.

Plasma irradiation on surface of heat-cured acrylic resin prior to processing self-curing acrylic resin is likely to effectively increase the adhesive strength between these materials for short-term period. However, long-term reliability of adhesive strength between these materials has not been clarified yet. In the present study, these materials were stored in water for a long period (100 days), and the effect on their shear bond strength was investigated. Forty-four test specimens with flat bonding test surface were made with heat-cured acrylic resin. They were divided into four groups according to treatment procedures for bonding surface: plasma treatment, adhesive primer application, adhesive primer application after plasma treatment, and no treatment (for control). Self-curing acrylic resin was processed against all bonding surfaces. After storage in water for 100 days, shear bond strength values between heat-cured and self-cured acrylic resins were measured. Specimens in plasma treatment group exhibited higher shear bond strength value than those in control, although the difference was not significant.

Objectives: The purpose of this study was to evaluate the performance of both single and double applications of (Adper Prompt L-Pop) self-etching dental adhesive, when used with three classes of light-activated restorative materials, in comparison to the performance of each restorative system adhesive. Evaluation parameters to be considered for the adhesive systems were (a) immediate marginal adaptation (or gap formation) in tooth cavities, (b) free setting shrinkage-strain determined by the immediate marginal gap-width in a non-bonding Teflon cavity, and (c) their immediate shear bond-strengths to enamel and to dentin., Methods: The maximum marginal gap-width and the opposing-width (if any) in the tooth cavities and in the Teflon cavities were measured immediately (3 min) after light-activation. The shear bond-strengths to enamel and to dentin were also measured at 3 min., Results: For light-activated restorative materials during early setting (<3 min), application of Adper Prompt L-Pop exhibited generally superior marginal adaptation to most system adhesives. But there was no additional benefit from double application. The marginal-gaps in tooth cavities and the marginal-gaps in Teflon cavities were highly correlated (r = 0.86-0.89, p < 0.02-0.01). For enamel and dentin shear bond-strengths, there were no significant differences between single and double applications, for all materials tested except Toughwell and Z 250 with enamel., Significance: Single application of a self-etch adhesive was a feasible and beneficial alternative to system adhesives for several classes of restorative. Marginal gap-widths in tooth cavities correlated more strongly with free shrinkage-strain magnitudes than with bond-strengths to tooth structure.

Objectives: Plasma treatment leads to surface modification such as the improved wettability of dental materials. Studies have suggested that plasma treatment may bring about an improvement in the shear bond strength between cobalt-chromium alloy and self-curing acrylic resin., Methods: Forty-eight cobalt-chromium alloy specimens were randomly divided into four groups (each of the groups consisted of 12 specimens); air abrasion, adhesive primer, adhesive primer after air abrasion, or after plasma irradiation. A self-curing acrylic resin, 2 mm thick and 3.6 mm in diameter, was processed on all specimens before storage in distilled water at 37 degrees C for 24 h. Shear bond strength values were determined at a crosshead speed of 0.5 mm/min. Data was statistically analyzed using Scheffé's test., Results: Adhesive primer clearly increased the shear bond strength compared with air abrasion (p < 0.05). The synergy of air abrasion and adhesive primer greatly increased the shear bond strength, showing a five-fold increase over air abrasion, or one and a half-fold over adhesive primer. A similar tendency in increase was observed in the adhesive primer after plasma treatment, but to a lower degree. Adhesive primer after plasma treatment showed half the shear bond strength of the treatment of adhesive primer after air abrasion (p < 0.05). Moreover, adhesive primer after plasma treatment showed a lower shear bond strength than adhesive primer alone although the difference was not statistically significant., Significance: Plasma treatment does not improve adhesion between cobalt-chromium alloy and self-curing acrylic resin., (Copyright 2004 Academy of Dental Materials)

Objectives: The purpose of this study was to explore multiple correlations between shrinkage, bonding and marginal gap parameters, immediately after light-activation, for three classes of restorative materials. The correlations of interest were between: (a) their marginal gap formation in tooth cavities, (b) their free setting shrinkage-strain determined by two different measurement methods ((i) the marginal gap-width in a non-bonding Teflon cavity and (ii) a linear (diametral) measure of shrinkage-strain), and (c) their shear bond strengths to enamel and to dentin., Methods: The maximum marginal gap width and the opposing width (if any) in the tooth cavity were measured immediately (3 min) after light-activation. Two factors for the setting shrinkage-strain and the shear bond strength to enamel and to dentin were measured concomitantly., Results: Out of the set of restorative materials investigated, those that produced a smaller marginal gap in the tooth cavity had a smaller marginal gap in the Teflon cavity. There was a highly significant correlation between the two parameters (r=0.914, p<0.001). However, no relationship was observed between the marginal gap in the tooth cavity and the immediate diametral shrinkage-strain (p>0.05). Thus the restorative materials that produced a smaller marginal gap in the tooth cavity did not generally have a smaller diametral setting shrinkage-strain. Furthermore, no relationship was observed between the marginal gap in the tooth cavity and the shear bond strength to enamel or to dentin (p>0.50)., Significance: For light-activated restorative materials during the early stage of setting (<5 min), the free shrinkage-strain, measured by marginal-gaps in Teflon cavities, had a greater correlation with immediate marginal-gaps in tooth cavities than either the immediate diametral shrinkage-strain or the bond strengths to the tooth structure.

This study evaluated the effects of polishing after one-day storage in water on the marginal gap formation around fillings using three resin-modified glass ionomers, one compomer, one conventional glass ionomer, and one micro-filled composite as a control. The study also examined the marginal gap and bond strength in Teflon cavities and the flexural strength of these restorative materials, which may influence the marginal gap formation. Immediately after the setting procedure, the specimen was polished and a marginal gap of approximately 10-25 micrometers was observed regardless of the type of restorative material used. In contrast, we observed no gap or a 1-2 micrometer gap width when the specimens were polished after one-day storage. Only Dyract did not show this pattern. Statistical difference was observed between immediately polishing and polishing after one-day storage in all materials except Dyract. Hygroscopic expansion, bond strength and flexural strength play important roles in reducing the marginal gap in tooth cavities filled with two types of glass-ionomer restorative materials. In contract, these properties did not play important roles in reducing the marginal gap width for Dyract.

This study evaluated the effect of primer on shear bond strength and marginal gaps of six new compomers immediately after light-activation. A resin-modified glass ionomer cement, a conventional glass-ionomer cement and a microfilled composite were used for comparison. The marginal gap widths of each of the four compomers and a microfilled composite used with the primer were significantly smaller compared with those used without the primer. The bond strength values of five compomers used with the primer were significantly higher than those used without the primer. The bond strength of conventional glass-ionomer was not affected by the primer (or the conditioner).

Gluma-treated dentin was covered with various resins before a microfilled composite was applied. The strength of the bond between dentin and composite established by this procedure was measured in shear and tensile tests. The effectiveness of the bonding was further tested by the width of the marginal contraction gap around fillings made in dentin by the above procedure. Resins containing propanal promoted shear bond strength of about 15 MPa. The tensile bond strength exceeded 22 MPa by one of the resins, but could not be measured because of frequent rupture in the composite. Between 30 and 70% of the fillings were without contraction gaps when propanal or p-toluenesulfinate-containing resins were used. It is proposed that oxygen inhibition of the polymerization on the dentin surface suppresses the bonding. Resins containing reducing agents may reduce oxygen inhibition and increase bonding by the adhesive.

Cylindrical dentin cavities, pretreated with Gluma and various resins, were filled with Silux, P-30, or Concise. Marginal integrity was in most instances obtained when experimental resins containing propionic aldehyde were used. The bond between composite and dentin established in this way was tested by load-cycling. Cervical located cavities in extracted human teeth, approximately one-half of the margins in dentin, were etched and treated as above. Fillings made of Silux, P-30, or Concise exhibited margins without stain upon axial loading in most cases. The frequency of staining increased when Dycal was used as cavity liner, but were absent in all cases when Concise was used as filling material. The content of propionic aldehyde in the intermediary resin layer may reduce the oxygen tension at the interface and thereby increase the rate of the polymerization at this location.

The walls of cylindrical cavities in human dentin were treated with Gluma and various resins before filling with either a microfilled or a macrofilled composite (Silux, P-30 or Concise). The extent of gaps (crevices) along the tooth/filling interface was observed before and after thermal cycling at restorations polished either 10 min or 24 h after curing of the composite. Application of a resin containing polymerization initiators and 1% propanal before filling with Silux or Concise resulted in restorations without contraction gaps along the tooth/filling interface. When P-30 was used in this procedure, one of six of the fillings exhibited gaps, but none of the six did so when removal of the marginal excess was postponed for 24 h.

Studies have suggested that irradiation with a CO2 laser may improve the shear bond strength between resin cement and zirconia. One hundred and ten specimens of zirconia randomly divided into four groups, of which we respectively treated the first three with air abrasion, irradiation with a CO2 laser, and irradiation with a CO2 laser followed by air abrasion, with the fourth group serving as an untreated control. Resin cement create a column 2 mm thick and 3.6 mm in diameter on each ceramic specimen. The shear bond strength between the resin and ceramic was determined at a crosshead speed of 0.5 mm/min. The bond strength between the resin and laser-treated ceramic varied with the laser power setting at which the ceramic was treated. The strength was greatest at a power setting of 8W, with a value of 6.7 MPa. Combined treatment of the zirconia ceramic with CO2 laser irradiation and air abrasion produced a threefold greater strength of the resin-to-ceramic bond over that with the zirconia control and a 20% greater strength between the resin and the ceramic treated with air abrasion. The CO2 laser irradiation of zirconia ceramic can significantly increase the adhesive strength of its bonding to a dental resin cement. [ABSTRACT FROM AUTHOR]

The effect of storage in water on the marginal adaptation of glass-ionomer restorations placed in extracted human premolars and Teflon molds was studied. When the cavity preparations were filled with a glass ionomer and polished immediately after setting, a marginal gap of approximately 15µm was formed. In contrast, when polishing following storage in water the marginal gap was 0 to 2µm for the resin-modified and the conventional glass ionomers respectively. The bond strength of the glass ionomer to enamel and to dentin and the flexural strength of the glass ionomer increased after storage in water. Therefore the marginal seal of glass-ionomer restorations may not only be improved due to hygroscopic expansion during storage in water but also may exhibit greater bond strength. [ABSTRACT FROM AUTHOR]