Bonding Strength of Universal Adhesives to Indirect Substrates: A Meta-Analysis of in Vitro Studies

Dentin Bonding Durability of Four Different Recently Introduced Self-Etch Adhesives

The objectives of this study were to evaluate the bonding durability of four different self-etch adhesives to dentin after 24 h and thermal cycling (TC) and to measure the degree of polymerization conversion (DC) in situ. Two-step self-etch adhesives, Clearfil SE Bond 2 (SE2, Kuraray Noritake Dental) and G2-Bond Universal (G2B, GC), and one-step self-etch adhesives, Scotchbond™ Universal Plus Adhesive (SBU, 3M ESPE) and Clearfil Universal Bond Quick (UBQ, Kuraray Noritake Dental), were used. The labial surfaces of bovine teeth were ground to create flat dentin surfaces. The adhesives were applied according to the manufacturers' instructions. After resin composite buildup and 24 h water storage, the specimens were sectioned into beams and all groups were subjected to thermal stress for 0, 10,000 (10k), or 20,000 (20k) cycles followed by micro-tensile bond strength (µTBS) testing. In situ DC was investigated with a laser Raman microscope. The µTBS data were statistically analyzed and subjected to a Weibull analysis. The different groups were compared at the characteristic strength (63.2% probability of failure) (α = 0.05). Two-Way ANOVA was used to show the effect of different adhesives and thermal cycling on the mean DC% followed by Tukey's multiple comparison post hoc test. G2B/TC10k resulted in a significant increase in the µTBS compared to TC0. SBU/TC20k showed significantly higher µTBS compared to TC0. For comparison between different tested adhesives, SBU showed a significantly lower µTBS compared to G2B after TC10k. G2B and SBU showed a greater number of adhesive failures after TC. Mean DC% was different for each adhesive. The newly developed MDP- and HEMA-free 2-SEA showed similar bonding performance with the gold-standard 2-SEA. However, there is still room for further improvement in terms of SEAs.

Influence of luting strategies on dentin bond performance of self-adhesive resin luting cement in combination with a universal adhesive

OBJECTIVES

This study aimed to evaluate the dentin bond performance of various resin luting cement (RLC) systems combined with universal adhesives in different luting strategies.

MATERIALS AND METHODS

Three self-adhesive resin luting cements (SRLCs) were used with universal adhesives as primers. Twelve specimens per group were prepared to measure shear bond strength (SBS) under distinct luting strategies in etch-&-rinse and self-etch modes. Regarding luting strategies, the bonded specimens were categorized into four groups based on tooth primer application and the curing mode of the SRLC paste: (i) with light irradiation of the tooth primer (wL) + dual-cure mode (DC) of the SRLC paste, (ii) wL + self-cure mode (SC) of the SRLC paste, (iii) without light irradiation of the tooth primer (woL) + DC mode of the SRLC paste, and (iv) woL + SC mode of the SRLC paste. Specimens were also subjected to different storage conditions: 24 h in water (baseline condition) and 10,000 cycles of thermal cycling.

RESULTS

Luting strategy, storage condition, and SRLC system type significantly influenced dentin SBS values in both etching modes. Notably, certain SRLCs exhibited significantly higher dentin SBS when the primer was light-irradiated compared with no primer irradiation.

CONCLUSION

Most SRLCs demonstrated higher dentin bond strength with light-irradiated primers, suggesting potential enhancement of dentin bond performance via primer light irradiation.

Effect of Surface Treatment and Resin Cement on the Bond Strength of an Advanced Lithium Disilicate

OBJECTIVES

 The aim of the study was to evaluate the effect of surface treatment and resin cement on the bond strength of conventional and advanced lithium disilicates (ALDs).

MATERIALS AND METHODS

 Ceramic slices (2 × 13 × 15 mm) of conventional lithium disilicate (LD) (IPS e.max CAD) and ALD (CEREC Tessera) were sectioned, polished, and divided into 16 groups (n = 10) according to the factors: ceramic, surface treatment, and resin cement (Panavia V5 and Variolink Esthetic DC). Surface treatments consisted of hydrofluoric acid 4.9% etching for 20 seconds (Hf20) or 30 seconds (Hf30), self-etching ceramic primer (Se), and sandblasting (Sb). Then, a resin cement cylinder (Ø = 2.5 mm) was manufactured on each specimen's surface. The specimens were then submitted to a shear bond strength (SBS) test. Surface roughness was evaluated through a contact profilometer, and surface morphology was evaluated under scanning electron microscopy for qualitative analysis.

STATISTICAL ANALYSIS

 Two-way analysis of variance (ANOVA) was used to analyze the data of SBS and surface roughness. For bond strength, the effects of surface treatment, resin cement, and the interaction were analyzed for each ceramic. For roughness, analyzed factors include ceramic and surface treatment.

RESULTS

 ANOVA revealed that ceramic (p = 0.047) and surface treatment (p < 0.001) factors affected the bond strength, while the cements performed similarly. Both materials showed adequate bond strength (ALD 19.1 ± 7.7 MPa; LD 17.1 ± 7.9 MPa). Sb protocol showed the lowest mean value (9.6 ± 2.9 MPa) compared with Hf20 (22.0 ± 7.1 MPa), Hf30 (21.7 ± 7.4 MPa), and Se (19.3 ± 6.0 MPa).

CONCLUSION

 For both ceramics, the highest performance was obtained after applying Se and Hf20 or Hf30. Therefore, longer etching time is unnecessary. Sb protocol must be avoided.

Scanning electron microscopy observation of dentin bond interfaces in different types of resin luting cements

This study aimed to observe and compare the resin luting cement (RLC)/dentin interfaces of different types of RLC systems with scanning electron microscopy (SEM). This study evaluated six self-adhesive resin luting cement systems (SARLCs), four systems combining a SARLC with a tooth primer (SARLCPs), and six conventional resin luting cement systems (CVRLCs). Cured resin composite rods were bonded to bovine dentin using RLCs in different etching modes. The morphological features at the interfaces were observed using SEM. Although all RLCs in etch-&-rinse (ER) mode showed a clear hybrid layer, most SARLCs had a thinner and more porous hybrid layer than the SARLCPs and CVRLCs. All SARLCPs with primer and CVRLCs showed a thin high-density layer below the primer layer in both etching modes. CVRLCs and SARLCPs with primer treatment systems may be more versatile and reliable when compared to simplified RLC systems.

Comparing Various Resin Luting Cement Systems in Different Etching Modes Through Bond Durability and Morphological Features

OBJECTIVES

This study aimed to investigate bond performance of various resin luting cement (RLC) systems on enamel and dentin in different etching modes and to compare the RLC-tooth interface morphology using scanning electron microscopy (SEM).

METHODS AND MATERIALS

The self-adhesive RLC systems used in combination with universal adhesives were as follows: Scotchbond Universal Adhesive Plus + RelyX Universal (3M Oral Care) and Clearfil Universal Bond Quick ER + SA Luting Multi (Kuraray Noritake Dental). These RLC systems were also used alone as self-adhesive RLC systems without universal adhesives (self-adhesive mode). The conventional RLC systems for comparison materials were as follows: BeautiBond Xtream + ResiCem EX (Shofu) and Tooth Primer + Panavia V5 (Kuraray Noritake Dental). Twelve specimens were prepared for each group to measure shear bond strength (SBS) in different etching modes. A stainless-steel rod was used as a substitute for indirect restorations. Bonded specimens were allocated to baseline (stored for 24 hours) and artificially aged (thermocycling [TC] for 10,000 cycles) groups. Representative treated tooth surfaces and RLC-tooth interfaces were observed using SEM.

RESULTS

Three-way analysis of variance (ANOVA) revealed that all the factors (etching mode, storage period, and RLC system) had a significant influence on the enamel SBS values (p<0.05). Enamel SBS was significantly higher in etch-&-rinse (ER) mode than in self-etch (SE) mode, regardless of RLC system or storage period. Three-way ANOVA showed that all the factors had a significant influence on the dentin SBS values (p<0.001). Most RLC systems showed significantly higher dentin SBS in SE mode than in ER mode, regardless of storage period. However, the combination with Scotchbond Universal Adhesive Plus and RelyX Universal showed no significant difference in SBS values between etching modes at the baseline and showed a significantly higher SBS value in ER mode than in SE mode after TC.

CONCLUSIONS

The self-adhesive RLC systems with universal adhesives tended to show higher enamel and dentin bond performance than the self-adhesive RLC systems alone. The morphology of treated tooth surfaces and resin cement-tooth interfaces were dependent on the RLC system and etching mode used. The RLC systems with primer application showed a thin, high-density layer above the intact dentin in both etching modes, suggesting chemical interaction.

Effect of universal adhesives and self-etch ceramic primers on bond strength to glass-ceramics: A systematic review and meta-analysis of in vitro studies

STATEMENT OF PROBLEM

To simplify dental procedures, multicomponent products such as universal adhesives and self-etch ceramic primers have been recommended for glass-ceramic bonding; however, studies have shown a wide range of results.

PURPOSE

The purpose of this systematic review and meta-analysis was to analyze the in vitro bond strength promoted by hydrofluoric acid+silane-containing universal adhesives and a self-etch ceramic primer to glass-ceramics and compare it with that of conventional treatments.

MATERIAL AND METHODS

A systematic search was conducted in the PubMed/Medline, Scopus, LILACS, and ISI Web of Science databases up to April 2021. In vitro studies assessing the resin-mediated bond to glass-ceramics by using a self-etch ceramic primer and hydrofluoric acid+silane-containing universal adhesives and/or compared with traditional hydrofluoric acid+glass-ceramic primers were included. Selection of studies, data extraction, and risk-of-bias analysis were performed. Statistical analysis was performed by using a review management software program using a random effects model (α=.05).

RESULTS

A total of 33 studies were included in the qualitative analysis and 26 studies in the quantitative analysis. Bond strength to lithium disilicate ceramic was higher when a hydrofluoric acid+glass-ceramic primer was used than when using a hydrofluoric acid+silane-containing universal adhesive (P<.05), except when 9% to 10% acid concentration was used in combination with static aging (P=.100). A self-etch ceramic primer promoted bond strength values to lithium disilicate that were similar to those of the hydrofluoric acid+glass-ceramic primer (P>.100).

CONCLUSIONS

Hydrofluoric acid+silane-containing universal adhesive was not as effective as the hydrofluoric acid+glass-ceramic primer in promoting bond strength to glass-ceramic. Bond strength values generated by a self-etch ceramic primer to glass-ceramic were similar to those generated by the conventional treatment.

Influence of different curing modes on the bonding effectiveness of self-adhesive resin luting cements in combination with universal adhesives

OBJECTIVES

This study aimed to investigate the immediate dentin bond performance and bond durability of self-adhesive resin luting cements (RLCs) in combination with universal adhesives in different curing modes.

METHODS

Two self-adhesive RLCs were used with universal adhesives as primers. They were also used alone as self-adhesive RLCs. Two multiple-step RLC systems were used as comparison materials. To measure the shear bond strength (SBS) in different curing modes, 12 specimens were prepared for each group. Stainless-steel rods were bonded to bovine dentin, and the bonded specimens were assigned to the baseline group (stored for 24 h) and artificially aged group (thermal cycling [TC], 10,000 cycles). After each storage period, the SBS of the bonded specimens was measured. The Knoop hardness number (KHN) of the cured RLCs was measured with or without primer application in different curing modes at 24 h and after 10,000 TC. The representative RLC/dentin interfaces were observed using scanning electron microscopy (SEM).

RESULTS

Dentin SBS was significantly influenced by the RLC system but not by the curing mode. Self-adhesive RLCs alone showed significantly lower SBS values than self-adhesive RLCs with primer regardless of the curing mode or storage period. The storage period, curing mode, and RLC system significantly influenced the KHN.

SIGNIFICANCE

The use of universal adhesives as a primer may help enhance the immediate dentin bond performance and bond durability of self-adhesive RLCs.

"No-Primer" Resin Cementation of Lithium Disilicate Ceramic: A Microtensile Bond Strength Evaluation

OBJECTIVE

The objective of this study was to evaluate the resin-ceramic adhesion of a long-carbon-chain silane (LCSI)-containing resin cement.

METHODS

Polished lithium disilicate ceramic discs were etched with hydrofluoric acid and randomly assigned into four groups; (PSAP), cemented using a silane-free resin cement with no prior priming; (PSAP-S), primed using a silane-containing primer before cementation using a silane-free resin cement; (PSAU), cemented using a LCSI-containing resin cement with no prior priming; (PSAU-S), primed as for the group (PSAP-S) and cemented using a LCSI-containing resin cement. The cemented blocks were sectioned into microbeams. The resin-ceramic microtensile bond strength (μTBS) was measured at 1 week and after thermocycling. The failure modes of the tested microbeams were evaluated.

RESULTS

The μTBS of the LCSI-containing and silane-free resin cements, either with or without a prior priming step, did not significantly differ. The adhesion of the LCSI-containing resin cement to lithium disilicate ceramic, either with or without a prior priming step, did not significantly deteriorate after artificial aging.

CONCLUSIONS

The long-carbon-chain silane (LCSI) monomer incorporated in the resin cement eliminated the need for a silane priming step of a hydrofluoric acid-etched lithium disilicate ceramic.

Influence of surface treatments and adhesive protocols on repair bond strength of glass-matrix and resin-matrix CAD/CAM ceramics

OBJECTIVE

To specify the effects of self-etching ceramic primer, Monobond Etch and Prime (MEP), and universal adhesive (UA) on repair bond strength between CAD/CAM blocks and resin composite.

MATERIALS AND METHODS

Vita Mark II (VM), IPS e.max CAD (EMAX), Shofu Block HC (SHC), and Tetric CAD (TET) blocks were sliced and thermocycled. They were divided into four groups according to surface treatments (n = 24): control, sandblasting (AL), hydrofluoric acid etching (HF), and MEP application. SEM analysis assessed surface topography. Subdivided, specimens followed distinct adhesive protocols (n = 12): control (silane + adhesive [SA] or adhesive [A] only for MEP group) and UA. Microshear bond strength (μSBS) was measured following resin composite repair. Data were analyzed using two-way ANOVA and Tukey tests (p < 0.05).

RESULTS

The μSBS of CAD/CAM blocks was significantly influenced by surface treatment type and adhesive protocol. The highest μSBS values for each block, considering surface treatment + adhesive protocol, were VM, HF + SA, or HF + UA; EMAX, MEP + A; and SHC and TET, AL + SA, or AL + UA.

CONCLUSIONS

Except for EMAX, it was not the adhesive protocol that made the significant difference in bond strength for each CAD/CAM block, but the surface treatment. MEP + UA application on glass ceramics lowered μSBS values significantly, so it is not recommended in clinical conditions.

CLINICAL SIGNIFICANCE

Repair is an essential therapeutic option, particularly in esthetic restorations, to swiftly repair the impaired esthetics caused by fracture. Repair protocol is dependent on the restorative material, and to have a reliable repair bond strength, the following surface treatment and adhesive protocol combinations are recommended for each CAD/CAM block: VM, HF + SA, or HF + UA; EMAX, MEP + A; and SHC and TET, AL + SA, or AL + UA.

Bonding stability of universal adhesives to feldspathic ceramic with or without prior silane application

PURPOSE

This study aimed to assess the bonding stability of three universal adhesives to a CAD-CAM feldspathic ceramic with or without prior silane application.

MATERIALS AND METHODS

The universal adhesives tested were Ambar Universal (FGM), Single Bond Universal (3M), and Ybond Universal (Yller). Scotchbond Multipurpose Plus (3M) was used as a control. The silane used was RelyX Ceramic Primer (3M). Microtensile bond strength (μTBS) to Vitablocs Mark II was measured after 24 h or 6 months of water aging (n = 20). Failure modes were observed through scanning electron microscopy, and pH and degree of C=C conversion (DC) of the adhesives were measured (n = 3). Data were analyzed using one-, two-, and three-way ANOVA.

RESULTS

The pH values differed significantly among the adhesives (p < 0.001), while the DC was similar (p = 0.141). The universal adhesives showed significant differences in μTBS, with higher immediate results when using silane and lower results after aging. Notably, a significant decrease in μTBS was observed after 6 months when silane was applied. In contrast, the control adhesive exhibited consistent results between the 24-h and 6-month storage periods. The universal adhesives showed a decrease in μTBS ranging from 25.5% to 40.1% after prolonged storage. Adhesive failures were predominant in all groups. The presence or absence of silane in the adhesive composition did not affect the bonding performance.

CONCLUSIONS

The application of a separate silane coupling agent improved the immediate bond strength of universal adhesives to CAD-CAM feldspathic ceramic. However, this bond strength significantly decreased after 6 months of water aging. The bond strength remained stable for universal adhesives when applied without silane after 6 months of aging.

Effects of Different Primers on the Bond Strength to Properly and Excessively Etched Ceramic-coated Zirconia

PURPOSE

To determine the effects of various primers on the immediate and long-term bond strength of ceramic-coated ultratranslucent zirconia that is properly or excessively etched.

METHODS AND MATERIALS

Ceramic-coated zirconia plates were etched with 9.5% hydrofluoric acid (HF) for 2 or 5 minutes, after which the surface morphology and elemental composition were examined. The etched specimens were treated with different primers including methacryloyloxydecyl dihydrogen phosphate (MDP)-only containing primer, silane-only containing primer, MDP and silane-containing ceramic primer as well as MDP and silane-containing adhesive system. For surface contact angle and shear bond strength (SBS) data, the difference between groups was evaluated by one-way analysis of variance (ANOVA) and three-way ANOVA factorial analysis, respectively. The statistical significance level of 0.05 was set and the Tukey test and the Dunnett-T3 test were used for post-hoc multiple comparisons.

RESULTS

Excessive etching (9.5% HF for 5 minutes) led to overconsumption of the glass layer and exposure of zirconia substrate compared to proper etching (9.5% HF for 2 minutes). Among different primers, the surface contact angle of the silane-only containing primer group was the lowest. The silane-only containing primer and MDP and silane-containing ceramic primer produced higher shear bond strength of properly and excessively etched ceramic-coated zirconia, respectively, both before and after thermal aging.

CONCLUSIONS

The silane-only containing primer and MDP and silane-containing primer can obtain better immediate and long-term shear bond strength for properly and excessively etched ceramic-coated zirconia, respectively.

Three-Dimensional Printed Resin: Impact of Different Cleaning Protocols on Degree of Conversion and Tensile Bond Strength to a Composite Resin Using Various Adhesive Systems

The present investigation tested the effect of cleaning methods and adhesives on the tensile bond strength (TBS) of a resin-based composite luted to a temporary 3D printed resin. Substrates (n= 360) were printed using a Rapidshape D20II and cleaned with a butyldiglycol-based solution, isopropanol, or by centrifugation. Specimens were air-abraded with Al₂O₃ (mean particle size 50 µm) at 0.1 MPa followed by pretreatment (n = 30/subgroup) with: (1) Clearfil Ceramic Primer (CCP); (2) Clearfil Universal Bond (CUB); (3) Scotchbond Universal Plus (SUP) or 4. Visio.link (VL) and luted to PanaviaV5. TBS (n = 15/subgroup) was measured initially (24 h at 37 °C water) or after thermal cycling (10,000×, 5/55 °C). The degree of conversion (DC) for each cleaning method was determined prior and after air-abrasion. Univariate ANOVA followed by post-hoc Scheffé test was computed (p < 0.05). Using Ciba-Geigy tables and chi-square, failure types were analyzed. The DC values were >85% after all cleaning methods, with centrifugation showing the lowest. CCP pretreatment exhibited the lowest TBS values, with predominantly adhesive failures. The combination of CCP and centrifugation increased the TBS values (p < 0.001) compared to the chemical cleaning. CUB, SUP, and VL, regardless of cleaning, can increase the bond strength between the 3D printed resin and the conventional luting resin.

Efficacy of adhesive strategies for restorative dentistry: A systematic review and network meta-analysis of double-blind randomized controlled trials over 12 months of follow-up

PURPOSE

The efficacy of etch-and-rinse, selective enamel-etching, and self-etching protocols for universal adhesives in follow-ups of over 12 months was compared in a network meta-analysis.

STUDY SELECTION

Randomized controlled trials (RCTs) published from 1998 to 2022 that compared marginal staining, marginal adaptation, retention and fractures, post-operative sensitivity, or recurrence of caries that took place over 12-months post-restoration were selected. A network meta-analysis determined the performance of each adhesive protocol.

RESULTS

After screening 981 articles, 16 RCTs were subjected to data extraction. Of which, 674 patients with 2816 restorations, were included in the network meta-analysis. The pooled risk of marginal discoloration following self-etching was significantly higher than that following etch-and-rinse at over 12, 24, and 36 months, which was time-dependent. The pooled risks of unfavorable marginal adaptation and unfavorable retention and fractures following self-etching were also significantly higher than that following etch-and-rinse, with the rates of unfavorable retention and fractures in non-carious cervical lesions increasing in a time-dependent manner. The pooled risks of marginal discoloration, unfavorable marginal adaptation, retention and fractures were similar between etch-and-rinse and selective enamel-etching protocols. Post-operative hypersensitivity and recurrence of caries were not significantly different among etch-and-rinse, selective enamel-etching, and self-etching protocols.

CONCLUSIONS

In follow-ups over 12 months, esthetic and functional outcomes of restorations completed with an etch-and-rinse adhesive protocol were superior to the ones achieved with a self-etching strategy without selective enamel-etching. Selective enamel etching is recommended for self-etching systems. Biological responses were similar for all three adhesive strategies.

Shear Bond Strength of a Direct Resin Composite to CAD-CAM Composite Blocks: Relative Contribution of Micromechanical and Chemical Block Surface Treatment

This study aims to compare the shear bond strength (SBS) of a direct resin composite to CAD-CAM resin composite blocks treated with different surface treatments: micromechanical, chemical or a combination of both. Eight CAD-CAM resin composite blocks, namely Brilliant Crios, Cerasmart 270, Vita Enamic, Grandio block, Katana Avencia, Lava Ultimate, Tetric CAD and Shofu Block HC were chosen. The micromechanical surface treatment protocols tested were hydrofluoric acid, polyacrylic acid or sandblasting, and the chemical one was a universal primer. These treated CAD-CAM blocks were tested to determine the SBS of a light-curing composite resin Z100 bonded to their surface. Two-way ANOVA followed by Tukey’s post hoc test was used to investigate the difference in SBS. Failures were analyzed by Fisher’s exact test. Bonding interfaces were examined by scanning electron microscopy. The micromechanical surface treatments give the highest SBS values: sandblasting appears to be the most efficient procedure for dispersed filler composite blocks, while hydrofluoric acid etching is preferable for polymer-infiltrated ceramic network (PICN) blocks. The use of universal primer does not improve SBS values on dispersed filler composite blocks. For PICN blocks, the use of universal primer significantly increases SBS values when combined with hydrofluoric acid etching.

Immediate bond performance of resin composite luting systems to saliva-contaminated enamel and dentin in different curing modes

The purpose of this study was to evaluate the immediate shear bond strength of resin composite luting systems to tooth with or without saliva contamination in different curing modes. The Knoop hardness number of the resin composite luting agents was measured. Four combinations of resin composite luting systems were used. The shear bond strength to bovine teeth was measured with and without saliva contamination in different curing modes at different storage periods. The Knoop hardness number of the resin composite luting agents was also evaluated. Significantly lower enamel and dentin shear bond strengths and Knoop hardness number values were observed in all resin composite luting systems at 5 min versus 24 h, regardless of the curing mode or saliva contamination. The influence of the curing mode of the resin composite luting systems on shear bond strengths and Knoop hardness number was dependent on material. For the saliva contamination conditions, only G-CEM ONE EM did not show any significant difference in shear bond strength among the groups with and without saliva contamination, regardless of curing mode, storage period, or tooth substrate. All the resin composite luting systems showed lower shear bond strengths and Knoop hardness number values immediately after setting.

In Vitro Performance of Different Universal Adhesive Systems on Several CAD/CAM Restorative Materials After Thermal Aging

OBJECTIVE

To evaluate the microshear bond strength (mSBS) of 10 universal adhesive systems applied on five different CAD/CAM restorative materials, immediately and after thermal aging.

METHODS AND MATERIALS

Five CAD/CAM materials were selected: 1) feldspathic glass ceramic (FeCe); 2) pre-polymerized reinforced resin composite (ReRC); 3) leucite-reinforced glass ceramic (LeGC); 4) lithium disilicate (LiDi); and 5) yttrium-stabilized zirconium dioxide (ZiDi). For each material, 15 blocks were cut into four rectangular sections (6 × 6 × 6 mm; n=60 per group) and processed as recommended by the respective manufacturer. For each indirect material, the following adhesive systems were applied according to the respective manufacturer's instructions: 1) AdheSE Universal [ADU]; 2) All-Bond Universal [ABU]; 3) Ambar Universal [AMB]; 4) Clearfil Universal Bond [CFU]; 5) Futurabond U [FBU]; 6) One Coat 7 Universal [OCU]; 7) Peak Universal Bond [PUB]; 8) Prime&Bond Elect [PBE]; 9) Scotchbond Universal Adhesive [SBU]; 10) Xeno Select [XEN, negative control]. After the application of the adhesive system, cylinder-shaped transparent matrices were filled with a dual-curing resin cement (NX3) and light cured. Specimens were tested in shear mode at 1.0 mm/ min (mSBS), after 24 hours and 10,000 thermal cycles (TC). All data were submitted to statistical analysis (α=0.05).

RESULTS

For FeCe, there was no significant decrease in mean mSBS for AMB, FBU, and SBU after TC when compared at 24 hours. For ReRC, AMB and SBU showed higher mean mSBS when compared to CFU and XEN, after 24 hours and TC. For LiDi, FBU and OCU showed higher mean mSBS when compared to CFU and XEN, after 24 hours and TC. For LeGC, AMB and PUB showed higher mean mSBS when compared to XEN, after 24 hours and TC. For ZiDi, OCU and SBU showed higher mean mSBS when compared to XEN, after 24 hours and TC. In addition, PBE and XEN showed the lowest mean mSBS after TC with higher percentage of bond strength reduction.

CONCLUSIONS

The mean mSBS among the different universal adhesives varied widely for each CAD/ CAM material used. In addition, most universal adhesives underwent a statistically significant bond strength reduction after TC.

Direct and semi-direct resin composite restoration in large cavity preparations: analysis of dentin bond strength stability and bottom/top microhardness ratio in a cavity model

To evaluate the influence of the restorative approach and aging time on dentin bond strength (BS), failure mode (FM), and bottom/top microhardness ratio (B/T) in a large dentin cavity model. A total of 102 bovine incisors were used to produce models of conical dentin cavities (4.0 mm thickness × 4.8 mm top diameter × 2.8 mm bottom diameter), which were restored using semi-direct filling (SDF) (Filtek™ Z250 XT + Scotchbond™ Universal/RelyX™ Ultimate luting system), direct bulk filling (DBF) (Filtek™ One Bulk Fill), and direct incremental filling (DIF) (Filtek™ Z250 XT) techniques. B/T, BS, and FM (n = 17) were analyzed in a microhardness tester, a universal testing machine, and a stereomicroscope, respectively, after 24 h and 6 months of water storage. BS and B/T data were analyzed using two-way ANOVA/Tukey post-hoc test (p < 0.05), while FM data were analyzed descriptively. There was a statistically significant difference in BS between the restorative techniques, and BS was influenced by aging time in the DBF and SDF groups. Mixed failure was predominant for the SDF technique in both aging times. There was no statistically significant difference in B/T among the restorative approaches regardless of the aging time (p > 0.05). Although all restorative approaches provided similar B/T, the semi-direct technique showed better performance on the material bond strength to dentine in large cavities.

Clinical outcome of bonded partial indirect posterior restorations on vital and non-vital teeth: a systematic review and meta-analysis

OBJECTIVES

The survival rate of indirect partial adhesive restorations on vital versus endodontically treated teeth is still controversial. The hypothesis is that there may be a difference in the survival rate of partial adhesive restorations performed on non-vital teeth compared to vital teeth.

MATERIALS AND METHODS

This systematic review was conducted following the PRISMA guidelines. The considered clinical studies investigated the outcomes of adhesive inlays, onlays, and overlays conducted over the past 40 years, focusing on Kaplan-Meier survival curves to calculate the hazard ratio (primary objective) and the survival rate (secondary objective) between vital and non-vital teeth. The risk of bias was assessed using the Newcastle-Ottawa Scale. Studies included in the review were identified through bibliographic research on electronic databases ("PubMed," "Scopus," "Cochrane Central Register of Controlled Trial," and "Embase"). The K agreement between the two screening reviewers was evaluated.

RESULTS

A total of 55,793 records were identified on PubMed, Scopus, and other bibliographic sources, and after the application of the eligibility and inclusion criteria, eight articles were included for qualitative analysis and six for quantitative analysis. The meta-analysis of the primary and secondary outcomes demonstrated that hazard ratios (HR = 8.41, 95% CI: [4.50, 15.72]) and survival rates (OR = 3.24, 95% CI: [1.76, 5.82]) seemed more favorable for indirect partial adhesive restorations on vital teeth than for those on endodontically treated teeth.

CONCLUSIONS

Within the limits of this study, these findings suggest that the risk of failure of indirect partial adhesive restorations on endodontically treated teeth is higher than on vital teeth.

CLINICAL RELEVANCE

The use of partial adhesive restorations on vital and endodontically treated teeth showed different long-term clinical outcomes.

An in-vitro study investigating the effect of air-abrasion bioactive glasses on dental adhesion, cytotoxicity and odontogenic gene expression

OBJECTIVE

To assess the microtensile bond strength (MTBS) and interfacial characteristics of universal adhesives applied on dentine air-abraded using different powders. The analysis includes the cytotoxicity of the powders and their effect on odontogenic gene expression.

METHODS

Sound human dentine specimens were air-abraded using bioglass 45S5 (BAG), polycarboxylated zinc-doped bioglass (SEL), alumina (AL) and submitted to SEM analysis. Resin composite was bonded to air-abraded or smear layer-covered dentine (SML) using an experimental (EXP) or a commercial adhesive (ABU) in etch&rinse (ER) or self-etch (SE) modes. Specimens were stored in artificial saliva (AS) and subjected to MTBS testing after 24 h and 10 months. Interfacial nanoleakage assessment was accomplished using confocal microscopy. The cytotoxicity of the powders was assessed, also the total RNA was extracted and the expression of odontogenic genes was evaluated through RT-PCR.

RESULTS

After prolonged AS storage, specimens in the control (SML) and AL groups showed a significant drop in MTBS (p > 0.05), with degradation evident within the bonding interface. Specimens in BAG or SEL air-abraded dentine groups showed no significant difference, with resin-dentine interfaces devoid of important degradation. The metabolic activity of pulp stem cells was not affected by the tested powders. SEL and BAG had no effect on the expression of odontoblast differentiation markers. However, AL particles interfered with the expression of the odontogenic markers.

SIGNIFICANCE

The use of bioactive glass air-abrasion may prevent severe degradation at the resin-dentine interface. Unlike alumina, bioactive glasses do not interfere with the normal metabolic activity of pulp stem cells and their differentiation to odontoblasts.

Annual review of selected scientific literature: A report of the Committee on Scientific Investigation of the American Academy of Restorative Dentistry

The Scientific Investigation Committee of the American Academy of Restorative Dentistry offers this review of the 2020 professional literature in restorative dentistry to inform busy dentists regarding noteworthy scientific and clinical progress over the past year. Each member of the committee brings discipline-specific expertise to this work to cover this broad topic. Specific subject areas addressed include prosthodontics; periodontics, alveolar bone, and peri-implant tissues; implant dentistry; dental materials and therapeutics; occlusion and temporomandibular disorders (TMDs); sleep-related breathing disorders; oral medicine and oral and maxillofacial surgery; and dental caries and cariology. The authors focused their efforts on reporting information likely to influence day-to-day dental treatment decisions with a keen eye on future trends in the profession. With the tremendous volume of dentistry and related literature being published today, this review cannot possibly be comprehensive. The purpose is to update interested readers and provide important resource material for those interested in pursuing greater detail. It remains our intent to assist colleagues in navigating the extensive volume of important information being published annually. It is our hope that readers find this work useful in successfully managing the dental patients they encounter.

Clinical performance of two different adhesive strategies for metal-ceramic cracks repairing and related in vitro study

To evaluate the bonding reliability of a universal adhesive compared to a commercial ceramic repair system for metal-ceramic cracks. In vitro part: sixty specimens with porcelain, metal and porcelain-metal substrate were fabricated. Half specimens were bonded by Singlebond Universal adhesive and Filtek Z350 resin composite. The other were processed by Ceramic Repair N. Shear bond strength was tested. In vivo part: forty patients with sixty ceramic fractured porcelain-fused-metal restorations were involved. Half were repaired by Singlebond Universal and Filtek Z350. The other were restored by Ceramic Repair N. The mean observation period was 65 weeks. Results showed the bond strength ranged from 13.97 MPa to 15.85 MPa using two different repair system on different substrate with no statistical difference. There was no statistical difference between the two adhesive system in survival rate according to Kaplan-Meier analysis. The universal adhesive had a similar repair performance compared to commercial ceramic repair system.

Bond Strength of Universal Adhesives to Dentin: A Systematic Review and Meta-Analysis

Currently, the availability of a wide variety of universal adhesives makes it difficult for clinicians to choose the correct system for specific bonding situations to dentin substrate. This study aimed to determine whether there are any alternative techniques or additional strategies available to enhance the bond strength of universal adhesives to dentin through a systematic review and meta-analysis. Two reviewers executed a literature search up to September 2020 in four electronic databases: PubMed, ISI Web of Science, Scopus, and EMBASE. Only in vitro studies that reported the dentin bond strength of universal adhesives using additional strategies were included. An analysis was carried out using Review Manager Software version 5.3.5 (The Nordic Cochrane Centre, The Cochrane Collaboration, Copenhagen, Denmark). The methodological quality of each in vitro study was assessed according to the parameters of a previous systematic. A total of 5671 potentially relevant studies were identified. After title and abstract examination, 74 studies remained in systematic review. From these, a total of 61 studies were included in the meta-analysis. The bond strength of universal adhesives to dentin was improved by the use of one of the following techniques: Previous application of matrix metalloproteinases (MMP) inhibitors (p < 0.001), prolonged application time (p = 0.007), scrubbing technique (p < 0.001), selective dentin etching (p < 0.001), non-atmospheric plasma (p = 0.01), ethanol-wet bonding (p < 0.01), prolonged blowing time (p = 0.02), multiple layer application (p = 0.005), prolonged curing time (p = 0.006), and hydrophobic layer coating (p < 0.001). On the other hand, the use of a shortened application time (p = 0.006), and dentin desensitizers (p = 0.01) impaired the bond strength of universal adhesives to dentin. Most of the analyses performed showed a high heterogenicity. The in vitro evidence suggests that the application of universal adhesives using some alternative techniques or additional strategies may be beneficial for improving their bonding performance to dentin. This research received no external funding. Considering that this systematic review was carried out only with in vitro studies, registration was not performed.

The Cytotoxicity and Genotoxicity of Three Dental Universal Adhesives-An In Vitro Study

Dental universal adhesives are considered an useful tool in modern dentistry as they can be used in different etching techniques, allow for simplified protocol and provide sufficient bond strength. However, there is still no consensus as to their toxicity towards pulp. Thus, the present study aimed to evaluate the cytotoxicity and genotoxicity of three universal adhesives: OptiBond Universal, Prime&Bond Universal and Adhese in an in vitro experimental model, monocyte/macrophage cell line SC (ATCC CRL-9855). The cytotoxicity was measured by means of XTT assay, whereas the genotoxicity (comet assay) was evaluated based on the percentage of DNA present in the comet tail. Furthermore, the ability of the adhesives to induce apoptosis was analyzed using flow cytometry (FC) with the FITC annexin V/propidium iodide (PI) double staining. The analysis of the cell cycle progression was performed with FC using PI staining. OptiBond Universal presented significant, while Prime&Bond Universal and Adhese Universal had minimal cytotoxicity and genotoxicity towards human SC cells. Moreover, only OptiBond Universal increased the level of apoptosis in SC cell line. None of the adhesives showed significant cell cycle arrest, as revealed by FC analysis. Due to substantial differences in toxicity in in vitro studies of dental adhesives, there is a great need for further research in order to establish more reliable test protocols allowing for standardized methodology.

Different bonding agents effect on adhesive bond strength: lithium disilicate glass ceramic

Abstract Introduction The silanization of the ceramic surface prior to applying the adhesive and/or resinous materials plays an important role in bond strength. Nowadays, a new family of adhesive systems has been introduced into the market, aiming to simplify the technique of adhesive procedures during cementation. Objective To investigate the effectiveness of different bonding agents containing silane and primer on Lithium Disilicate Glass Ceramic (LD) surface by shear bond strength tests. Material and method 130 LD ceramic blocks were included in acrylic resin, polished and washed in ultrasound for 10 minutes. The specimens were divided into 2 groups according to surface treatment: Polished Surface (PS); Hydrofluoric Acid 9.5% - 20s (HF). Each group was divided into 5 subgroups (n = 13) according to bonding agent type: metallic primer containing MDP (ZPrimePlus, Bisco Inc); two traditional silanes (MonobondPlus, IvoclarVivadent / Porcelain Prime, Bisco Inc.); mixture of silane and resin (Kerr Silane, Kerr); mixture of silane and universal adhesive (Single-bond Universal, 3M Espe). The specimens were mounted in a standard device for shear testing (UltradentBonding Assembly), cemented with dual resin cement (RelyX UltimateTM, 3M Espe.) and photo-polymerized for 20s. The samples were tested after 24 hours and 3 months of storage in distilled water at ±36 °C. The data were analyzed by 3-Way Anova and Tukey's test (α = 5%). Result Shear bond strength (SBS) was significantly influenced by surface treatment, bonding agent used and storage (p <0.001). Conclusion Adequate adhesive bond strength to Lithium Disilicate Glass Ceramic can be obtained with traditional silanes, combined with HF acid pretreatment surface.