Bonding of restorative materials to dentin with various luting agents

The aim was to compare eight types of luting agents when used to bond six indirect, laboratory restorative materials to dentin. Cylinders of the six restorative materials (Esteticor Avenir [gold alloy], Tritan [titanium], NobelRondo [feldspathic porcelain], Finesse All-Ceramic [leucite-glass ceramic], Lava [zirconia], and Sinfony [resin composite]) were ground and air-abraded. Cylinders of feldspathic porcelain and glass ceramic were additionally etched with hydrofluoric acid and were silane-treated. The cylinders were luted to ground human dentin with eight luting agents (DeTrey Zinc [zinc phosphate cement], Fuji I [conventional glass ionomer cement], Fuji Plus [resin-modified glass ionomer cement], Variolink II [conventional etch-and-rinse resin cement], Panavia F2.0 and Multilink [self-etch resin cements], and RelyX Unicem Aplicap and Maxcem [self-adhesive resin cements]). After water storage at 37°C for one week, the shear bond strength of the specimens (n=8/group) was measured, and the fracture mode was stereomicroscopically examined. Bond strength data were analyzed with two-factorial analysis of variance (ANOVA) followed by Newman-Keuls' Multiple Range Test (α=0.05). Both the restorative material and the luting agent had a significant effect on bond strength, and significant interaction was noted between the two variables. Zinc phosphate cement and glass ionomer cements produced the lowest bond strengths, whereas the highest bond strengths were found with the two self-etch and one of the self-adhesive resin cements. Generally, the fracture mode varied markedly with the restorative material. The luting agents had a bigger influence on bond strength between restorative materials and dentin than was seen with the restorative material.     

The optimum combination of dentin bonding systems.

The efficacy of dentin bonding systems composed of a commercial or an experimental dentin cleanser, a dentin primer, and an intermediate resin was examined by measurement of the wall-to-wall polymerization contraction gap. Light-activated composites in a cylindrical dentin cavity were prepared in exposed dentin of the proximal surface of the extracted human premolar. The combination of a dentin cleanser of neutralized 0.5 mol/L EDTA, a dentin primer of 35% hydroxyethyl methacrylate (HEMA) or 35% HEMA containing 5% glutaraldehyde and a commercial intermediate resin (Clearfil New Bond, Kuraray Co., Osaka, Japan; Pyrofil Light Bond, Sankin Co., Osaka, Japan) was effective in compensating for the contraction stress of a light-activated composite and for obtaining marginal integrity between the composite and the dentin cavity wall.     

Dentin bonding as a function of dentin structure

The traditional principles of operative dentistry have been challenged since Dr. Buonocore introduced the aid-etch technique in 1955. In spite of the numerous changes in clinical protocols and adhesive techniques, adhesion to dentin remains difficult. The importance of micromechanical bonding to dentin has been recognized over the last decade. Researchers now believe that dentin adhesion relies primarily on the penetration of adhesive monomers into the filigree of collagen fibers left exposed by acid etching. Two main strategies are currently in use for bonding to enamel and dentin: the self-etch technique and the total-etch technique. The efficiency of either bonding strategy depends very much on the dentin substrate used for bonding. Laboratory tests use ideal dentin from extracted teeth, which does not reflect the clinical reality. Clinical studies are the ultimate test for any dental adhesive material.     

Pulpal responses to various dentin bonding systems in dentin cavities.

The purpose of this study was to investigate pulpal response and bacterial invasion associated with five dentin bonding systems placed in cavities without an enamel margin. Two hundred and twenty-four dentin margin cavities were created by removing the surrounding marginal enamel of class V cavities in monkey teeth. These cavities were restored with a resin composite using various current dentin bonding systems. All of the dentin bonding systems showed odontoblastic layer changes to varying degrees, and slight to moderate inflammation at the initial stage. With the lapse of time, the degree of inflammation tended to decrease markedly, except for those cases in which bacteria were present. The result of SA/Photo Bond corresponded to that of the glass ionomer cement (negative control). Accordingly, this study suggests that a good bond and adaptation between resin and dentin should be obtained for eliminating pulpal irritation, even in the dentin cavity.     

Dentin adhesives: site of dentin vs. bonding of composite resins

The effect of the site of dentin in extracted human teeth on early bond strength of 3 dentin adhesives, Clearfil new bond, Gluma Dentin Bond and Scotchbond, was investigated. The bond strength registered on dentin close to the pulp was consistently only 30% to 40% of the strength found on peripheral dentin. The smaller the dentin thickness towards the pulp the larger is the percentage area of dentinal tubuli. A relationship was established between the percentage area of solid dentin available for bonding, i.e. the total area of dentin minus the percentage area of exposed dentinal tubuli, and the shear bond strength acquired. It is presumed that the results of the present study offer an explantation for the widely differing bond strength figures reported in different studies. However, it is unlikely that the present in vitro findings will have an impact on bond strength in vivo when the priciples of conservative cavity preparation as applied in adhesive dentistry are followed.     

应用牙本质屏障法测定牙齿充填材料体外细胞毒性

目的:探讨牙本质屏障法用于牙齿充填材料体外细胞毒性试验测定的特点。方法:低速锯片切新鲜拔除的磨牙,获取紧邻牙髓的颊侧牙本质片,选择通透值相近的牙本质片作为牙本质屏障,制作细胞毒性体外测试装置,用此装置测定氧化锌丁香油水门汀、复合树脂、玻璃离子水门汀、氢氧化钙水门汀、磷酸锌水门汀及阴性对照材料和阳性对照材料的细胞毒性,同时用传统的浸提液法测定这5种材料的细胞毒性。结果:牙本质屏障法测定的5种材料的细胞相对活性(%)分别为89.1±3.6、81.8±3.7、96.4±2.8、96.2±1.8、74.5±2.8;浸提液法测定的5种材料的浸提原液细胞相对活性(%)分别为35.6±5.2、72.9±4.3、91.5±1.3、90.2±2.6、59.3±2.6。结论:牙本质屏障可以显著减少充填材料对细胞的毒性作用,牙本质屏障法更能反映充填材料的体内细胞毒性。     

TMPT对实验牙本质封闭剂与树脂水门汀粘接性能的影响

目的:探讨TMPT添加型实验牙本质封闭剂对树脂水门汀粘接性能的影响.方法:通过添加不同比例的TMPT于“劲润”牙本质保护膜(HyC)中试制牙本质封闭剂T0、T33、T67和T100,采用剪切强度测试结合体式显微镜观察断面破坏方式,评价各组实验牙本质封闭剂与Super-Bond C＆B(SU)、Panavia F(PA)及G-CEM(G-CEM)等不同种类水门汀之间的粘接性能.结果:SU与各组实验牙本质封闭剂之间粘接力均较强,达20 MPa以上;G-CEM及PA与T0之间粘接力分别为16.60和12.26 MPa.随着TMPT的添加,SU组粘接力呈现增大趋势,而G-CEM与PA组呈现减小趋势.结论:HyC及TMPT添加型实验牙本质封闭剂与Super-Bond C＆B的粘接性能较好.     

Edge strength of indirect restorative materials

Objectives

To evaluate the edge strength and fracture patterns of different all-ceramic and indirect composite materials used in prosthodontic applications.

Methods

Fourteen rectangular-shaped samples (2–2.5 mm thick) were prepared of each of the following materials: BelleGlass NG (Kerr) (BG), fibre-reinforced BelleGlass/EverStick (Kerr/Stick Tech Ltd.) (BGES), Vita Mark II (Vita Zahnfabrik) (VMII), bilayered IPS e.max Ceram/CAD (Ivoclar-Vivadent) (Ceram/CAD), bilayered IPS e.max Ceram/ZirCAD (Ivoclar-Vivadent) (Ceram/ZirCAD) and unilayered IPS e.max CADLT (Ivoclar-Vivadent) (CADLT). Each group was further subdivided into seven subgroups (n = 2) corresponding to different edge distances at which samples were loaded. Samples were tested with an edge strength machine (CK10, Engineering Systems, Nottingham, UK) using a diamond Vickers indenter. The force-to-failure (N) was recorded and four readings were obtained per sample. The mode of failure was analysed microscopically. One-way ANOVA was used to detect differences in edge strength among the groups and correlation and regression analyses were used to detect the correlation between distance of loading and failure force.

Results

The mean values of edge strength (N) were 94.1 (11.2) for BG, 134.4 (10.9) for BGES, 50.5 (8.9) for VMII, 54.4 (7.5) for Ceram/CAD, 53.2 (8.4) for Ceram/ZirCAD and 69.1 (9.1) for CADLT. Significant (p < 0.05) strong positive linear correlations were found between the force-to-failure and edge distance among all groups. Three patterns of failure were identified: surface indentation without visible cracking, surface indentation with visible cracking and chipping.

Conclusions

Indirect composite materials had better edge fracture behaviour than all-ceramic materials. The addition of fibres enhanced the performance of the resin-composite material. Fracture strength increased as the distance from the edge increased. Edge fracture was restricted to the veneer material in bilayared systems and therefore a stronger veneer material is recommended.     

Immediate bonding effectiveness of contemporary composite cements to dentin

The objective of this study was to compare the one-week bonding effectiveness of nine contemporary composite cements used to lute ceramic to dentin and to determine an appropriate processing method for pretesting failures. The microtensile bond strengths (μTBS) of different luting agents including five self-adhesive cements (Unicem, 3 M ESPE; Maxcem, Kerr; Monocem, Shofu; G-Cem, GC; and Multilink Sprint, Ivoclar-Vivadent), two self-etch cements (Panavia F2.0 and Clearfil Esthetic Cement, Kuraray), and two etch-and-rinse cements (Calibra, Dentsply, and Variolink II, Ivoclar-Vivadent) were measured using a standardized protocol. As control, a two-step self-etch adhesive combined with a restorative composite (Clearfil SE+Clearfil APX, Kuraray) were included as luting material. Depending on the processing of the pretesting failures, two groups of cements could be distinguished: (1) those with low bond strength and many pretesting failures and (2) those with relatively high bond strength and few pretesting failures. Nevertheless, the control luting procedure involving a self-etch adhesive combined with a restorative composite presented with a significantly higher μTBS. The μTBS was clearly product-dependent rather than being dependent on the actual adhesive approach. Fracture analysis indicated that failure usually occurred at the dentin–cement interface especially for the cements with low bond strength and many pretesting failures. Depending on the cement system, an adequate immediate ceramic-to-dentin bond strength can be obtained, even with self-adhesive cements that do not use a separate dental adhesive. Yet, the self-etch adhesive Clearfil SE combined with the restorative composite revealed a superior bonding performance and should therefore be preferred in clinical situations where the restoration transmits light sufficiently.     

Retention of posts cemented with various dentinal bonding cements

This investigation evaluated the retention of preformed posts with four different cements: C & B Metabond, Panavia, All-Bond 2, and Ketac-Cem. Sixty intact maxillary canines were selected for the study. The clinical crowns were removed and endodontic therapy done on each root, which was then prepared to receive prefabricated posts. The 60 samples were divided into four groups of 15, and the posts in each group were cemented with one of the four cements. The roots were mounted in acrylic resin blocks and the posts were separated from the canals with an Instron testing machine. Analysis of the forces needed to dislodge the posts with analysis of variance and Student-Newman-Keuls test disclosed that C & B Metabond cement was the most retentive (p < 0.05). No difference in retention was recorded between Ketac-Cem and Panavia cements. All-Bond 2 cement was the least retentive of cements.     

Dentin treatment effects on the bonding performance of self-adhesive resin cements

Mazzitelli C, Monticelli F, Toledano M, Ferrari M, Osorio R. Dentin treatment effects on the bonding performance of self-adhesive resin cements. Eur J Oral Sci 2010; 118: 80–86. © 2010 The Authors. Journal compilation © 2010 Eur J Oral Sci
The effects of dentin surface treatments on the microtensile bond strengths and on the interfacial characteristics of self-adhesive resin cements were investigated. Flat dentin surfaces were obtained from human molars and were treated as follows: (i) no treatment of dentin; (ii) 0.1 M EDTA scrubbed for 60 s; or (iii) 10% polyacrylic acid applied for 30 s. Three self-adhesive cements were used to lute composite overlays on deep-coronal dentin surfaces in the presence of simulated pulpal pressure (15 cm of H₂O). Bonded specimens were cut into beams 1 mm thick and stressed in tension until failure. Fractured sticks were examined under a scanning electron microscope. Additional specimens were stained with Masson's trichrome and observed under light microscopy for interfacial evaluations. The bond strength to dentin of the hydrophobic and solvent-free cement (RelyX Unicem) was unaffected by the tested dentin treatments. The bond strength of the 2-hydroxyethyl methacrylate (HEMA)-based cement (Bis-Cem) decreased after treatment of dentin with EDTA and/or polyacrylic acid. The hydrophilic and water-containing cement (G-Cem) attained a higher bond strength when luted on polyacrylic acid-conditioned dentin. In conclusion, smear layer removal, opening of dentinal tubules, and the water content of dentin differently influence the bond strengths and the interfacial characteristics of self-adhesive cement–dentin interfaces.     

In vitro bonding efficacy of three restorative materials to primary dentin using a one-bottle adhesive system

The shear bond strength to primary dentin of a new single-bottle adhesive with three restorative materials (composite resin, compomer, and amalgam) was evaluated. Statistical analysis of the data showed significant differences among the means of the groups (ANOVA, p < 0.05). Composite resin and compomer were not significantly different from each other but both were statistically higher than amalgam. The fracture mode was not related to the shear bond strength values. The mean shear bond strengths obtained in this study were statistically comparable to those obtained in a previous study which used the same experimental design but included permanent teeth.     

Effect of various pretreatments for dentin bonding on dentin permeability

Pretreatment of the dentinal surface with acidic solution is now considered to be necessary to obtain strong bonding between dentin and resin materials. Effects of various surface treatments for dentin bonding on dentinal smear removal have been reported by SEM observation. In this study, changes of dentin permeability after the surface treatments were measured using Pashley's technique. Forty-second treatments with either phosphoric acid gel, aqueous phosphoric acid, 10-3 solution or aqueous 10-20 Ca solution (10% citric acid containing 20% CaCl2) produced greater increases in dentin permeability compared with the treatments using either 10-20 Ca gel, Tenure Conditioner, Scotchprep or Gluma 2 for 40 seconds. Treatments with primers including adhesive monomers such as Scotchprep and Mirage Conditioner also increased the dentin permeability by removal of the smear layers and smear plugs. Application of a bonding agent (Clearfil Photobond) for 1 minute did not remove the smear plugs and the dentin permeability remained the same as before the treatment. The changes in dentin permeability were not predictable by SEM observation in some cases.     

Principles and mechanisms of bonding with dentin adhesive materials

This article reviews six dentin bonding agents with regard to composition of the individual components of each of the systems. Adhesion mechanisms are discussed relative to the chemical compounds mediating the bond. Adjunctly, inspection of the bonding sites between the different adhesives and human dentin by scanning electron microscopy elucidates the bonds formed as far as detail reproduction as an indicator for wetting ability or mechanical interlocking.