Effect of filler contents on the bond strength of CAD/CAM resin crowns: New resin primer versus conventional silane agents.

Purpose This study aims to evaluate the effects of resin primers containing methyl methacrylate (MMA) and silane agent on the bonding effectiveness of indirect resin composite blocks with three different filler contents.Methods A commercially available computer-aided design/computer-aided manufacturing (CAD/CAM) resin composite block and two experimental resin composite blocks with different filler contents were alumina-blasted and two surface treatments (primer and silane agent) were applied. The resin cement was built up, and the micro-tensile bond strength (µTBS) was measured after 24 hours, 1 month or 3 months of water storage (n = 24 per group). The fracture surfaces after µTBS measurements and resin block/cement interface were observed by scanning electron microscopy (SEM).Results The primer treatment group showed a significantly higher bond strength than the silane group only in F0 (filler content 0 wt%) group (P < 0.001). In the primer group, F0 and F41 (filler content 41 wt%) groups showed significantly higher bond strengths than F82 (filler content 82 wt%) group (P < 0.001). In contrast, in the silane group, F41 group showed significantly higher bond strength than F0 and F82 groups (P < 0.001), and F82 group showed significantly higher bond strength than F0 group (P < 0.001). SEM revealed that the matrix resin was partially destroyed on the fracture surface of the primer group, and an uneven interface surface was observed compared with that of the silane group.Conclusions MMA-containing primers showed higher bonding effectiveness to CAD/CAM resin composite blocks than the silane treatment.

Effect of tooth temperature on the dentin bonding durability of a self-curing adhesives: The discrepancy between the laboratory setting and inside the mouth.

A two-bottle self-curing universal adhesive (Tokuyama Universal Bond; Tokuyama Dental) that does not require a long waiting time or light curing after application of the bonding material has been developed. This study aimed to evaluate the influence of tooth and adhesive temperature during the bonding procedure on the effectiveness of dentin bonding. The results showed that the tooth temperature affected the effectiveness of the dentin bonding; therefore, to determine the precise bonding ability in the laboratory, the temperature of the tooth must be raised until it is the same as that of the oral cavity. In addition, the temperature of the material did not affect bonding effectiveness; this result confirms that it does not matter whether the refrigerated product is used soon after its removal from the refrigerator or after it reaches room temperature in the clinic.

Does the bonding effectiveness of a fiber post/resin composite benefit from mechanical or chemical treatment? Seven methods for saliva-contaminated surfaces.

PURPOSE: This study examined four cleaning methods and three chemical treatments for artificial saliva-contaminated fiber posts in terms of bonding durability to resin composite core materials. METHODS: Non-contaminated fiber posts (Tokuyama FR Post, Tokuyama Dental) and those contaminated (GC Fiber Post, GC) with artificial saliva (Saliveht Aerosol, Teijin Pharma) were used. Washing and drying (WD), alcohol cleaning (AlC), H3PO4 etching (P/WD), alumina blasting (B/D) for decontamination and silanization (Clearfil Ceramic Primer Plus, Kuraray Noritake Dental, Si), resin priming (HC Primer, Shofu, MMA), and bonding resin application (Clearfil Universal Bond Quick, Kuraray Noritake Dental, BR) for chemical treatment were performed. The treated fiber post was planted inside a cylindrical tube and filled with resin composite (DC Core Automix ONE, Kuraray Noritake Dental). The specimen was sectioned, and a push-out test was performed after 24 h, 1 month, and 3 months. The fracture surface was observed using a scanning electron microscope (SEM). RESULTS: Adhesion between the non-contaminated fiber post and resin composite did not improve by silanization and decreased by alumina blasting. SEM observations revealed a fractured glass fiber by alumina blasting. Saliva contamination decreased the bond strength between the fiber post and resin composite; however, recovery was achieved by WD, Alc, P/WD, and B/D. Compared to Si, BR (P = 0.009) was effective in restraining the long-term durability of bonding, whereas MMA (P = 0.99) was not. CONCLUSION: The application of bonding resin after alcohol cleaning is the most convenient and effective clinical procedure for fiber post surface treatment.

Combination of a silane coupling agent and resin primer reinforces bonding effectiveness to a CAD/CAM indirect resin composite block.

The effects of silanization and resin primer application on CAD/CAM indirect resin composite block bonding were investigated. KATANA AVENCIA P blocks (Kuraray Noritake Dental) were treated with a silane coupling agent and/or a resin primer. The contact angles (CAs) of resin primer were observed before and after silanization. Panavia V5 (Kuraray Noritake Dental) was built after each treatment. Bond strengths were measured, and the interface was analyzed by energy dispersive X-ray spectroscopy (EDS). The CA showed that silane treatment improved the wettability of the resin primer to the resin block. The combination treatment of the silane and resin primer showed significantly higher bond strength than no treatment, only in the silanization or resin primer group (p<0.001 each). EDS analysis showed that the resin primer penetrated both cement and block sides. The combination of the silane and resin primer improved bonding effectiveness between the resin block and resin cement.

Status of decontamination methods after using dentin adhesion inhibitors on indirect restorations: An integrative review of 19 publications.

The purpose of this review was to assess the literature regarding the decontamination of resin cement before the luting procedure in order to provide clinicians with a comparative overview of decontamination effects. A total of 19 articles were selected for inclusion in this review. The results indicated that bonding effectiveness is reduced due to residual adhesion inhibitors such as saliva, blood, hemostatic agents, and temporary/provisional cement. Self-etching and self-adhesive systems tend to be more negatively affected by adhesion inhibitors than do etch and rinse systems. Cleaning with an ultrasonic scaler or rotating brush have demonstrated conflicting effects in several studies. Some studies have reported that phosphoric acid has negative effects and recommend mild acid for decontamination. The application of phosphoric acid followed by sodium hypochlorite has been shown to help avoid negative effects. Alumina blasting has been investigated as a mechanical cleaning method in a relatively large number of experiments, most of which have confirmed its effectiveness. An intraoral cleaner containing functional monomers that has become commercially available in recent years is a promising method in clinical practice because it can easily and effectively remove temporary adhesive material. In addition, adhesion inhibitors can be easily removed from resin-coated dentin surfaces.

Do resin core build-ups obtain the benefits of higher bonding ability from direct or indirect technique?

Purpose This study evaluated the effects of different materials (composite resin system including a photo-cure adhesive (DC) vs. resin cement system including a self-etching primer (PV)) and techniques (direct vs. indirect) for resin core build-up on the bonding performance to root canal dentin.Methods The human teeth were decoronated and root canal preparation was performed. All specimens were randomly divided into four groups according to the combinations of the methods (Direct or Indirect) and the materials (DC: Clearfil DC Core, Kuraray Noritake Dental or PV: Panavia V5, Kuraray Noritake Dental). Micro-tensile bond strength (µTBS) and push-out tests were performed. Scanning electron microscope observations of the interface were also performed, and microcomputed tomography and optical coherence tomography were applied to evaluate the sealing ability.Results The Indirect group had significantly higher µTBSs than the Direct group in the DC group (P = 0.0076). The PV group had significantly higher bond strengths than the DC group in both the Direct and Indirect groups (P < 0.001). The Direct/PV group demonstrated significantly higher push-out bond strength than the Direct/DC group (P < 0.001). In the Direct/PV group, the formation of resin tags was observed even on the apical side of the canal. Microleakage was more clearly observed in the DC group than in the PV group.Conclusions PV has a higher bonding ability to root canal dentin than DC. When using DC, the indirect technique exhibited a higher bonding ability than the direct technique.

Back to the multi-step adhesive system: A next-generation two-step system with hydrophobic bonding agent improves bonding effectiveness.

This study evaluated the bonding effectiveness of a newly developed two-step hydrophobic bonding material. Three groups using different bonding systems were compared: BZF group, using the new bonding system (BZF-29; GC, Tokyo, Japan); GPB group, using a one-step bonding system (G-Premio Bond; GC); and SE2 group, using a two-step bonding system (CLEARFIL SE Bond 2; Kuraray Noritake Dental, Tokyo, Japan). Microtensile bond strength (µTBS) was measured after storage in water for 24 h, 3 months and 6 months (n=25/group). Fracture surfaces were observed under scanning electron microscopy. The BZF group showed significantly higher µTBS than the other groups (p<0.001). Dominant failure patterns were cohesive failure for the BZF group (48-84%), mixed failure for the SE2 group (48-60%) and interface failure between adhesive and resin composite for the GPB group (48-52%). The hydrophobicity of the BZF-29 bonding system improves the long-term bonding effectiveness between adhesive and resin composite.

MDP is effective for removing residual polycarboxylate temporary cement as an adhesion inhibitor.

The effect of cleaner containing 10-methacryloyloxydecyl dihydrogen phosphate (MDP) for removing temporary cement remnants on dentin surface was evaluated. Flat dentin surfaces were wet-polished (Co) and HY-BOND temporary cement hard (Shofu) was applied to the surface. This temporary cement was removed using an air-scaler (Sc), brush (Br), or phosphoric acid and NaOCl (NC). A prototype cleaner containing MDP (Kuraray Noritake Dental, Tokyo, Japan) was used with agitation mode (MC+AG). KATANA Avencia block (Kuraray Noritake Dental) was luted with SA Cement Plus Automix (Kuraray Noritake Dental). Co showed significantly higher bond strength than Sc or Br (p<0.001 each). Bond strengths with NC (p=0.99) and MC+AG (p=0.38) did not differ significantly from that with Co. Transmission electron microscopy revealed sufficient interaction of MC+AG. Cleaner containing MDP can effectively remove temporary cement by agitation, and can be expected to improve the chemical bonding ability by binding more MDP to dentin.

Adhesion procedures for CAD/CAM indirect resin composite block: A new resin primer versus a conventional silanizing agent.

PURPOSE: The purpose of this study was to evaluate the effectiveness of both a resin primer containing methyl methacrylate (MMA) and a silanizing agent on bonding to indirect resin composite blocks, using two types of build-up hybrid resin composites. METHODS: SHOFU BLOCK HC (Shofu) specimens were blasted with alumina, after which one of two surface treatments was applied: CERA RESIN BOND (Shofu, the Silane group) or HC primer (Shofu, the MMA group). Resin composites made using either Solidex Hardura (SDH, Shofu) or Ceramage Duo (CMD, Shofu) were built up and micro-tensile bond strength (µTBS) values were measured after storage in water for either 24h or 6 months (n=24 per group). The fracture surfaces after µTBS measurements and the resin block/build-up resin interfaces were observed by scanning electron microscopy (SEM). RESULTS: The bond strength of the Silane/SDH group significantly decreased after 6 months (p<0.001), whereas in the MMA group there was no significant loss after 24h or 6 months (p=0.99). In the CMD group, the bond strength after 6 months was significantly lowered in both the Silane group (p<0.001) and the MMA group (p<0.001), but the latter still showed greater adhesion. SEM images demonstrated that the matrix resin was partially destroyed at the fracture surfaces of the MMA group and fracture surface unevenness was observed. CONCLUSIONS: A primer containing MMA produced stronger bonding to CAD/CAM resin even after long-term aging compared to a silane treatment.

Effectiveness of pretreatment with phosphoric acid, sodium hypochlorite and sulfinic acid sodium salt on root canal dentin resin bonding.

PURPOSE: The purpose of this study was to evaluate the effect of pretreatment using phosphoric acid, sodium hypochlorite and sulfinic acid sodium salt on the bonding of one-step self-etching adhesives to root canal dentin. METHODS: Thirty-six single-rooted sound human premolars were randomly assigned into three groups before applying the one-step self-etching adhesive. These comprised a control group with no pretreatment, an NC group that received phosphoric acid and subsequent sodium hypochlorite gel pretreatments, and an NC+AC group that received an additional treatment with sulfinic acid sodium salt following the same pretreatment applied to the NC group. Microtensile bond strength measurements, bonding interface observations by scanning electron microscopy (SEM), elemental analyses by X-ray photoelectron spectroscopy (XPS) and degree of polymerization (DOP) analyses by Raman spectroscopy were subsequently performed. RESULTS: The bond strength was significantly higher in the NC+AC group than in the other two groups (Control: P=000.1 and NC: P=0.004). SEM observations showed that resin tags were present in the dentinal tubules in the NC and NC+AC groups. Compared to the control group, the adhesive resin layer had a lower DOP in the NC group, while the DOP for the NC+AC group was higher than that of the NC specimens. CONCLUSIONS: Bonding to root canal dentin was improved by applying sulfinic acid sodium salt in addition to treatment with phosphoric acid followed by sodium hypochlorite. The DOP of the adhesive resin was reduced by sodium hypochlorite and subsequently restored by applying sulfinic acid sodium salt.

Effectiveness of current adhesive systems when bonding to CAD/CAM indirect resin materials: A review of 32 publications.

The purpose of this review was to assess the available literature regarding bonding between current adhesive systems and computer-aided design/computer-aided manufacturing (CAD/CAM) indirect resin materials, to provide clinicians with a comparative overview of the relevant bonding procedures. An electronic search was performed through PubMed based on the keywords CAD/CAM and dental bonding. Additional relevant literature was obtained from the citations in the articles. A total of 313 papers were identified, of which 281 were excluded as being unsuitable, and an additional 3 papers were identified, giving a total of 32 articles that are included in this review. Based on this survey, it is recommended that microretentive surfaces should be generated by either blasting or hydrofluoric acid etching. This initial process should be followed by silanization to ensure chemical adhesion prior to bonding to CAD/CAM indirect resin composite materials (including Lava Ultimet, KATANA AVENCIA block, Gradia Block, Cerasmart, Paradigm, and Block HC) and CAD/CAM polymer-infiltrated ceramics (such as Vita Enamic). The use of materials containing methyl methacrylate (MMA) also appears to improve the bonding of CAD/CAM poly(methyl methacrylate) (PMMA) resin materials (including XHIPC-CAD/CAM, artBloc Temp, and Telio).

Effects of three drying methods of post space dentin bonding used in a direct resin composite core build-up method.

PURPOSE: The purpose of this study was to evaluate drying methods for post space dentin bonding in a direct resin composite core build-up method. METHODS: Experiment 1: Four root canal plastic models, having diameters of 1.0 or 1.8mm and parallel or tapered shapes, were prepared. After drying each post space using three drying methods (air drying, paper-point drying, or ethanol drying, which involves filling the space with 99.5 vol% ethanol followed by air drying), the residual liquid in the models was weighed. Experiment 2: Thirty endodontically treated single-root teeth were dried using the above-described drying methods and filled with dual-cure resin composite. The bonded specimens were sectioned into square beams of approximately 1mm2 for microtensile bond strength (µTBS) testing. Nine teeth were observed through transmission electron microscopy (TEM) and micro computed tomography (µCT). The weight of residual liquid and µTBS were analyzed using Scheffé multiple comparison. RESULTS: Experiment 1: The results of air drying were significantly different from those of paper-point drying (p<0.001) and ethanol drying (p<0.001), and no significant difference was observed between paper-point drying and ethanol drying. Experiment 2: The µTBS significantly decreased in the order of ethanol drying, paper-point drying, and air drying (air drying/ethanol drying: p<0.001, air drying/paper-point drying: p=0.048, ethanol drying/paper-point drying: p=0.032). TEM and µCT observation revealed a sufficient dentin/adhesive interface in the ethanol drying group. CONCLUSIONS: Ethanol drying was found to be more effective for post space dentin bonding, as compared with air drying and paper-point drying.

Adhesion procedure for CAD/CAM resin crown bonding: Reduction of bond strengths due to artificial saliva contamination.

PURPOSE: The present study aimed to elucidate how saliva contamination affects microtensile bond strength of resin cement to CAD/CAM resin blocks and identify a decontamination method that can restore original bond strength. METHODS: The KATANA AVENCIA block (Kuraray Noritake Dental) was sandblasted on the adherend surface (P-Co group). Then, the block was contaminated with artificial saliva (Saliveht Aerosol, Teijin). Air dry (N-Co), sandblasting (Sb) and phosphate acid cleaning (AT) groups were prepared. After silane treatment, PANAVIA V5 (Kuraray Noritake Dental) was built up and microtensile bond strength (µTBS) was measured after immersion in water (n=24 per group). Scanning electron microscopy (SEM) analysis, surface roughness and contact angle measurement of each surface were performed. RESULTS: The P-Co group showed the highest µTBS value, and bond strength was significantly lower in the N-Co group than the other groups (P<0.001). In all groups, decreased bond strength resulted from long-term water storage. In the N-Co group, a contaminated layer was observed on the surface by SEM and the contact angle was significantly smaller than the other groups (P<0.001). In Sb and AT groups, µTBS values that were reduced by artificial saliva contamination significantly increased but did not recover to P-Co group values (P<0.001). SEM showed no morphological difference between P-Co, Sb and AT groups. The Sb group showed increased surface roughness. CONCLUSION: The long-term durability of bonds between CAD/CAM resin blocks and luting agent cement was significantly reduced by artificial saliva contamination. However, sandblasting or phosphoric acid cleaning can recover bonding effectiveness by 75-85%.

Effectiveness of sodium hypochlorite and sulfinic acid sodium salt treatment on dentin-resin bonding: Long-term durability of one-step self-etching adhesive.

This study aimed to evaluate the effect of sulfinic acid sodium salt interposition after acid and sodium hypochlorite treatment (NC treatment) on dentin bonding durability using a mild type one-step self-etching adhesive. Fifteen human third molars were randomly assigned into three experimental groups according to dentin pretreatment before applying the one-step self-etching adhesive: Cont group, without pretreatment; NC group, pretreatment with phosphoric acid and sodium hypochlorite gel; and NC+AC group, additional treatment with sulfinic acid sodium salt followed by the same pretreatment of the NC group. Microtensile bond strength was measured and the pre-treated dentin surface, fracture modes, and bonding interface were observed. The bond strength of the NC+AC group was significantly higher than that of the other groups (p<0.001). The dentin-adhesive interface was degraded after 1 year only in the Cont group. Our results demonstrated NC treatment improves bonding durability and application of sodium sulfinic acid salt after NC treatment improves bonding effectiveness.