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Objectives: To evaluate the benefits of a novel dentin-bonding primer, namely, isocyanate-terminated urethane methacrylate precursor (UMP), which can form covalent bonds with demineralized dentin collagen., Methods: The synthesized and purified UMP monomer was characterized and tested its effects on the degree of conversion (DC) and wettability of an acetone-based dental adhesive. Then UMP primers of different concentrations were formulated and used to prepare adhesive specimens, which were compared with solvent-treated groups. Primer-treated specimens with and without aging were also compared. To evaluate the bonding interface, microtensile strength tests, nano-indentation tests and nanoleakage- eavaluation were performed using a field-emission scanning electron microscope and nano-indenter. Data were analyzed using SPSS 20.0 software with significance set at α = 0.05 using one-way analysis of variance (ANOVA) and two-way ANOVA to characterize the effects of the primer., Results: Treatment with the UMP primer promoted the DC and wettability of the adhesive on the demineralized dentin surface (P < 0.05); it also increased the bond strength of the aged dentin bonding interface (P < 0.05). Nanoleakage was reduced; the bonding interface became more stable, and the continuity and strength of the hybrid layer improved (P < 0.05) following UMP treatment. The application of 5 mM UMP as a primer for dentin bonding could lead to a stable bonding interface and long-lasting bonding effects., Significance: The use of 5 mM UMP primer developed in this study could improve dentin bonding durability and has excellent clinical application prospects., (Copyright © 2023 The Academy of Dental Materials. All rights reserved.)

Objectives: The humid oral environment adversely affects the interaction between a functionalised primer and dentine collagen after acid-etching. Robust adhesion of marine mussels to their wet substrates instigates the quest for a strategy that improves the longevity of resin-dentine bonds. In the present study, an etching strategy based on the incorporation of biomimetic dopamine methacrylamide (DMA) as a functionalised primer into phosphoric acid etchant was developed. The mechanism and effect of this DMA-containing acid-etching strategy on bond durability were examined., Methods: Etchants with different concentrations of DMA (1, 3 or 5 mM) were formulated and tested for their demineralisation efficacy. The interaction between DMA and dentine collagen, the effect of DMA on collagen stability and the collagenase inhibition capacity of the DMA-containing etchants were evaluated. The effectiveness of this new etching strategy on resin-dentine bond durability was investigated., Results: All etchants were capable of demineralising dentine and exposing the collagen matrix. The latter strongly integrated with DMA via covalent bond, hydrogen bond and Van der Waals' forces. These interactions significantly improve collagen stability and inhibited collagenase activity. Application of the etchant containing 5 mM DMA achieved the most durable bonding interface., Conclusion: Dopamine methacrylamide interacts with dentine collagen in a humid environment and improves collagen stability. The monomer effectively inactivates collagenase activity. Acid-etching with 5 mM DMA-containing phosphoric acid has the potential to prolong the longevity of bonded dental restorations without compromising clinical operation time., Clinical Significance: The use of 5 mM dopamine methacrylamide-containing phosphoric acid for etching dentine does not require an additional clinical step and has potential to improve the adhesive performance of bonded dental restorations., (Published by Elsevier Ltd.)

Purpose: To determine whether high-pressure air blowing during adhesive application affects the infiltration of resin comonomers and nanoleakage manifestation in the resin/dentin interface under simulated pulpal pressure., Materials and Methods: Thirty mid-coronal dentin surfaces were bonded with an etch-and-rinse adhesive (Adper Single Bond 2) under simulated pulpal pressure. In the control group, the adhesive was thinned by ordinary air blowing with a pressure of 0.2 MPa, while in the experimental group, a high-pressure air blowing technique (pressure: 0.4 MPa) was used. All other procedures followed the manufacturer's instructions. Resin tag formation and nanoleakage in the bonding interface were evaluated with scanning electron microscopy (SEM) and transmission electron microscopy (TEM)., Results: When adhesive was thinned with high pressure air blowing, longer and more homogeneous resin tags were formed. The bonding interface demonstrated good overall morphology and integrity. Almost perfect infiltration of resin and no obvious nanoleakage were observed., Conclusion: Thinning of adhesive with high-pressure air blowing provides a clinically feasible adjunctive procedure for better resin infiltration.

Our previous studies showed that biomodification of demineralized dentin collagen with proanthocyanidin (PA) for a clinically practical duration improves the mechanical properties of the dentin matrix and the immediate resin-dentin bond strength. The present study sought to evaluate the ability of PA biomodification to reduce collagenase-induced biodegradation of demineralized dentin matrix and dentin/adhesive interfaces in a clinically relevant manner. The effects of collagenolytic and gelatinolytic activity on PA-biomodified demineralized dentin matrix were analysed by hydroxyproline assay and gelatin zymography. Then, resin-/dentin-bonded specimens were prepared and challenged with bacterial collagenases. Dentin treated with 2% chlorhexidine and untreated dentin were used as a positive and negative control, respectively. Collagen biodegradation, the microtensile bond strengths of bonded specimens and the micromorphologies of the fractured interfaces were assessed. The results revealed that both collagenolytic and gelatinolytic activity on demineralized dentin were notably inhibited in the PA-biomodified groups, irrespective of PA concentration and biomodification duration. When challenged with exogenous collagenases, PA-biomodified bonded specimens exhibited significantly less biodegradation and maintained higher bond strengths than the untreated control. These results suggest that PA biomodification was effective at inhibiting proteolytic activity on demineralized dentin matrix and at stabilizing the adhesive/dentin interface against enzymatic degradation, is a new concept that has the potential to improve bonding durability.

Objectives: To evaluate the effect of luting cement and thermomechanical loading on the retention of glass fibre posts in root canals., Methods: One hundred and forty-four single-rooted human premolars were endodontically treated and restored with RelyX Fibre Posts. The teeth were divided into four groups according to the cements used (Fuji I, Fuji CEM, RelyX Unicem and RelyX ARC). Each group was further divided into two subgroups according to the method of ageing (immediately tested and after thermomechanical loading). Bond strength was evaluated using a pull-out test. Microleakage was examined quantitatively with dye penetration. The dentine-cement-post bonding interface was assessed using scanning electron microscopy. Data were analysed with two-way ANOVA (pull-out test) and Kruskal-Wallis analysis (microleakage)., Results: The pull-out bond strength and microleakage were significantly affected by the type of cement and ageing. Although RelyX ARC showed the highest bond strength before thermomechanical loading (p<0.05), the sealing ability of this cement was worse than those exhibited in Fuji CEM and RelyX Unicem (p<0.05). After thermomechanical loading, pull-out strengths of Fuji I and Fuji CEM were significantly increased, whereas that of RelyX ARC group significantly decreased (p<0.05). The sealing ability of Fuji CEM was significantly better than the two resin cement groups (p<0.05) after ageing., Conclusion: Fuji CEM demonstrates increased pull-out strength after thermomechanical loading and favourable sealing ability compared with the other cements., Clinical Significance: Resin-modified glass ionomer cements have the potential benefit of achieving long-term retention when used for luting glass fibre post to root canal dentine. So it may be recommended for the cementation of glass fibre post in clinics., (Copyright © 2013 Elsevier Ltd. All rights reserved.)

Purpose: To introduce a new fixation method for stick-shaped specimens for use in microtensile tests and to evaluate the effect of this new method on microtensile bond strength, failure modes, and stress distribution., Materials and Methods: Flat mid-coronal dentin surfaces were prepared on 12 caries-free human third molars and randomly divided into two groups for testing with two dental adhesives (Adper Single Bond 2 [SB2] and Clearfil SE Bond [SEB]). Following adhesive application and composite buildups, the bonded teeth were sectioned into beams. Sticks from each tooth were then equally divided into two subgroups for microtensile bond testing according to the utilized gripping devices (a flat Ciucchi's jig and the experimental setup). Failure modes were examined with a field-emission scanning electron microscope (FESEM). Three-dimensional models of each gripping device and specimen were developed, and stress distributions were analyzed by finite element analysis (FEA). Statistical significance was set at α = 0.05 RESULTS: Compared to those fixed using a flat Ciucchi's jig, sticks fixed with the experimental setup yielded lower bond strength values (p = 0.021 for SB2 and p = 0.007 for SEB) and more mixed failure patterns (p = 0.036 for both SB2 and SEB). In addition, the experimental setup guaranteed a uniaxial tensile force that was perpendicular to the bonding interface and produced a more uniform stress distribution at the bonding interface., Conclusion: An experimental setup for fixing microtensile sticks was proposed that was designed to provide a uniform stress distribution at the adhesive interface. FEA and failure mode analysis confirmed such uniform distribution, thus supporting the validity of the bond strength results obtained with this new fixture design.

Objective: To evaluate the effect of quaternary ammonium methacrylates incorporation into a dental adhesive on the resistance of enzymatic degradation of resin-dentine interfaces., Methods: Thirty caries-free extracted human third molars were randomly divided into three groups (n = 10): 2-methacryloxylethyl dodecylmethyl ammonium bromide (MAE-DB) incorporated adhesive served as the experimental group, pre-treatment with chlorhexidine (CHX) served as a positive control, Adper(TM) Single Bond 2 served as a negative control. The resin-dentin interfaces were prepared using total etch bond system. After storage in distilled water at 37 °C for 24 h, the bonded teeth were vertically sectioned into beams. Beams were respectively immersed in artificial saliva containing 2 g/L MMP-8 at 37 °C for 0 h, 24 h and 120 h (n = 30). Micro-tensile bond strength, failure modes and nanoleakage were examined., Results: There were no significantly differences of micro-tensile bond strength between groups before hydrolysis (P > 0.05). After the enzymatic hydrolysis of 24 h and 120 h, the micro-tensile bond strength of MAE-DB groups [(31.13 ± 8.77) MPa, (24.14 ± 6.64) MPa] were significantly higher than that of the negative control groups [(25.63 ± 6.90) MPa, (15.22 ± 6.57) MPa] (P < 0.05). Most of the failures were found in the base part of the hybrid layer in the negative control group, while failures occurred through the top of the hybrid layer in CHX and MAE-DB groups after the enzymatic hydrolysis.Specimens from each immediate group showed minor silver deposits in hybrid layer. After beams being enzymatic hydrolyzed for 120 h, it was shown that the silver nitrate uptake in the negative control group were significantly different from those in the CHX and MAE-DB groups (P < 0.05)., Conclusions: Dental adhesive incorporation of MAE-DB could improve the anti-degrade ability of resin-dentin interfaces.

The influence of different adherend and substrate materials on shear bond strength (SBS) test was estimated. Ceramic plates (IPS e.max press) were cut, polished, abraded, and applied with two resin cements (Panavia F/Biscem). The SBS values of 30 groups were measured. The groups consisted of five combinations of adherend and substrate materials for each adhesive system and three different bonded areas (2, 4, and 6 mm diameter) for each combination. The failure modes were examined using a stereomicroscope. Groups with ceramic adherends showed higher SBS values in both adhesive systems and all three bonded areas. Small bonded areas are associated with significantly high SBS values. Groups with similar bonded areas and high SBS values showed more mixed or cohesive failures. Groups with small bonded areas and high SBS values had more interfacial failures. Adherend and substrate material significantly influenced the in vitro SBS value.

Objective: To investigate the potential effect of proanthocyanidins (PA), a natural cross-linker, on the stability of resin-dentin bonds against thermal cycling., Methods: Ten percent, 15% PA-based preconditioners, and 5% glutaraldehyde were prepared for the transient pretreatment of demineralized dentin before bonding. Specimens without pretreatment were used as negative controls (n = 4 teeth for each group). Microtensile bond strength, failure mode, micromorphologies of resin-dentin interface and the collagen degradation of bonded specimens after thermal cycling were evaluated., Results: After thermal cycling, the microtensile bond strength values of resin-dentin bond in groups pretreated with 15% PA for 120 s and 60 s [(23.09 ± 3.19) and (21.88 ± 3.49) MPa] were significantly higher than that in control group [(15.47 ± 3.78) MPa] (P < 0.05). Mixed fractures were the most prevalent failure mode. Specimens with pretreatment presented compact hybrid layer, while some narrow gaps were found in hybrid layer of non-treated specimens. Collagen biodegradation rates in groups with pretreatment were significantly lower than that in control group (P < 0.05). Among them, specimens pretreated by 15% PA preconditioner for 120 s exhibited the lowest biodegradation rates [(0.316 ± 0.019) mg/g]., Conclusions: The application of natural cross-linker PA on demineralized dentin reduced the bond degradation against aging by thermal cycling, and can be helpful to create more durable bonds to dentin.

Purpose: To determine whether bonds of contemporary etch-and-rinse adhesives made with ethanol-wet bonding are stronger and more durable than those made with water-wet bonding, and to explore the possible reasons for the bonding results., Materials and Methods: Flat surfaces of midcoronal dentin were made in extracted human third molars. The dentin surfaces were randomized into 6 groups according to bonding techniques (water- vs ethanol-wet bonding) and dental adhesives [Single Bond 2 (SB), Prime Bond NT (PB), and Gluma Comfort Bond (GB)]. After etching and rinsing, dentin surfaces were either left water-moist or immersed in ethanol. Following adhesive application and composite buildups, the bonded teeth were sectioned into beams for microtensile bond strength evaluation with or without NaOCl challenge. The morphology of the hybrid layer was analyzed with SEM. The wettability of water- vs. ethanol-saturated dentin was evaluated. The concentrations of non-volatile ingredients in the adhesives were compared., Results: Compared to water-wet bonding, ethanol-wet bonding yielded similar (p > 0.05 for PB and GB) or higher (p < 0.05 for SB) 24-h bond strength, displayed significantly higher bond strength after chemical challenge (p < 0.05, for all three adhesives), and produced more even hybrid layers. Moreover, ethanol-saturated dentin exhibited a lower contact angle than water-saturated specimens, and the concentrations of non-volatile ingredients of the adhesives decreased in the order of SB > GB > PB., Conclusion: Ethanol-wet bonding could improve the bonding efficacy of contemporary etch-and-rinse adhesives, probably due to the good wettability of ethanol-saturated dentin and the structure of the hybrid layer. Moreover, this positive effect of ethanol-wet bonding might be influenced by the composition of adhesives.

Purpose: To evaluate the effect of two post-coating methods with dental adhesives on the bonding properties between fiber posts and core resin., Methods: Thirty-six fiber posts were randomly divided into 3 groups and treated as following: Group A, no treatment as control; Group B, coated with dual-cured XP bond and light curing; Group C, coated with XP bond and self-curing. All treated posts were cemented to Definit Core resin and made to stick-shape bonding specimens. All the specimens were subjected to microtensile bonding strength (μTBS) tests and scanning electronic microscopy (SEM) observation after storage in water for 24 h and 1 month, respectively. The results of μTBS tests were analyzed by SPSS13.0 software package., Results: After 24 h water storage, μTBS of Group C (17.03 MPa ± 6.01 MPa) was significantly higher than that of Group A (9.64 MPa ± 4.59 MPa) and Group B (11.99 MPa ± 6.07 MPa). After 1 month water storage. there was no significant difference among the three groups. The μTBS of Group B (8.17 MPa ± 4.25 MPa) and C (9.85 MPa ± 4.11 MPa) both decreased after 1 month water storage. Interfacial gaps were also detected in groups B and C after 1 month water storage under SEM., Conclusions: Effect of post-coating with adhesives on the immediate bonding strength between fiber posts and core resin depends on the curing mode of adhesives. Both two post-coating methods would decrease the bonding durability of fiber posts and core resin.

Objective: To evaluate the dentin and enamel bonding strength and resin-dentin interfaces of four resin cements., Methods: Twenty-four sound freshly extracted molars were sectioned with low-speed saw under running water. Two mesial-distal enamel disc and two buccal-lingual dentin discs were sectioned from each molar. Four resin cements (A group: Panavia(TM) F; B group: RelyX(TM) ARC; C group: RelyX(TM) Unicem; D group: Clearfil(TM) SA Cement) were applied to the surface of these enamel and dentin discs according to manufacturers' guidance. The bonded specimen were prepared for shear bond strength test and sectioned occluso-gingivally into two slabs for scanning electron microscopy (SEM) observation., Results: The bonding strength between resin and enamel in B group [(29.38 ± 6.28) MPa] was higher than that in D group [(27.25 ± 7.03) MPa], and both of them were significantly higher than those in A [(22.92 ± 7.13) MPa] and C group [(10.92 ± 3.41) MPa] (P < 0.05). The highest dentin bonding strength was shown in B group [(27.28 ± 6.79) MPa], followed by A [(14.23 ± 6.39) MPa], D [(10.09 ± 3.26) MPa] and C group [(6.43 ± 1.60) MPa, P < 0.05]., Conclusions: The four resin cements have different enamel or dentin bonding properties.

Purpose: To evaluate the effect of etching time on the nanoleakage and microtensile bond strength (microTBS) at the interface between etch-and-rise adhesives and dentin., Methods: Eighty molars were sectioned to expose the superficial dentin and randomly divided into four groups according to the adhesives used: OptiBond Solo (OB), Single Bond (SB), One-Step (OS), and Prime&Bond NT (PB). Within each group, a total-etching technique was applied, and the dentin surfaces were etched for 0, 15, 30 or 60 seconds. Each treated tooth was then sectioned into sticks. A non-trimming microTBS test and TEM observation for nanoleakage were sequentially performed., Results: The degree of nanoleakage increased as etching time increased (P < 0.05). For the OS and PB groups, the highest microTBS values were achieved with 15 seconds of etching, followed by 30, 60 and 0 seconds. For the OB and SB groups, the microTBS values for 15- and 30-second etching times were similar and were both significantly higher than those of 0 and 60 seconds (P < 0.05).

Purpose: To propose an experimental model for assessing the interfacial strength between post and luting agent under clinically relevant conditions of post space diameter and cement layer thickness., Materials and Methods: DentinPost (Komet, DP) and GC (GC) glass fiber posts were tested. A sample of 22 posts per type was randomly subdivided into two equal groups based on the material for cementation: Panavia F 2.0 (Kuraray, PF) and MultiCore Flow (Ivoclar Vivadent, MF). Within each group, 2 subgroups were defined depending on the procedure for specimen preparation. In subgroup A (NO-M), the resin cement was incrementally stratified around a post centered within a plastic matrix until the latter was filled. In subgroup B (M), first a mold of resin cement with an artificial post space was created. Then, using the same cement, the post was luted into the dowel space. Microtensile beams were cut and loaded to measure post/cement interfacial strengths. For statistical analysis of the data, Kruskall-Wallis ANOVA was applied, followed by Dunn's Multiple Range test (p < 0.05)., Results: Bond strengths in MPa were (median; 25th-75th percentile): DP/PF/M 4.5; 3.1-7.4; DP/PF/NO-M 9.2; 5.8-12.4; DP/MF/M 14.2; 10.2-20-6; DP/MF/NO-M 16.5; 13.1-21.7; GC/PF/M 7.6; 3.3-11.7; GC/PF/NO-M 7.8; 5.1-11-9; GC/MF/M 16.7; 14.3-3-22; GC/MF/NOM 20.4; 15.6-24. Irrespective of post type and of specimen preparation procedure, with or without mold, significantly higher bond strengths were measured for MF. On both post types, both cements achieved similar interfacial strengths regardless of the C-factor., Conclusion: The influence of a clinically relevant C-factor on the adhesion of resin cements to glass fiber posts was not statistically significant.

The purpose of this study was to evaluate the effect of silanization and light-irradiation on bonding between a fiber post and different resin-based luting agents. Sixty silicium fiber posts (Easy Post) were divided into 10 groups according to the type of resin-based luting agent employed, whether the post surface was silanized, whether the adhesive was light-irradiated, and whether Calibra luting agent was used. The micro-tensile bond strength and bonded interface of specimens in each group were evaluated. Specimens luted with Calibra or FluoroCore 2 resin-based luting agent systems were superior to those treated with Multilink or Variolink II, in terms of both bond strength and interfacial integrity. Application of silane, light-irradiation of the adhesive, or light-irradiation of the Calibra resin-based luting agent did not significantly increase the bond strength further. It can be concluded that Calibra or FluoroCore 2 resin-based luting agent systems are more suitable for luting prefabricated Easy Post in a clinical situation, while pre-silanization of the post surface and light-irradiation of XP Bond/SCA adhesive or resin-based luting agent may not be as important as hitherto considered.

Purpose: To evaluate the bond properties of Vitadur alpha on dental zirconia framework material., Methods: Vitadur alpha was sintered on the surface of four groups' presintered zirconia ceramic plates which were dealt with respective procedures. SEM, energy distribution spectrum and thermal shock test were applied to evaluate the sintering properties of such interfaces. Shear bond strength of Vitadur alpha-zirconia interfaces were measured, and the results were analysed by ANOVA method., Results: Satisfying result was obtained in Vitadur alpha sintered on the zirconia framework material, furthermore, chemical combination between the two laminates were confirmed by means of energy distribution spectrum. The shear bond strength of 3Y-TZP-Vitadur alpha dentin differed under different surface conditionings: highest shear bond strength appeared in the group conditioned with water sand paper (35.1662MPa), shear bond strength of the group conditioned with sandblast (27.8283MPa) was better than that of non-conditioning group (20.9677MPa), diamond condition group had the lowest shear bond strength (15.3025MPa), significant difference existed between each group (P<0.01)., Conclusion: Further clinical research could be carried out on Vitadur alpha and zirconia ceramic framework under conditioning with sandblast.

Objectives Bonding stability of resinous adhesives to dentin is still problematic and may involve regional variations in dentin composition. This study is to evaluate the effect of dentin depth on the stability of resin-dentin bonds under thermocycling challenge. Methods Dentin slabs with two flat surfaces parallel to the tooth axis were obtained from extracted human third molars. The slabs were randomized into eight groups according to the location of dentin [deep dentin (DD) or superficial dentin (SD)], the adhesive treatment (Single Bond 2 or Clearfil S 3 Bond), and the storage treatment (thermocycling for 5000 times vs. no). After the adhesive treatment and composite buildup on the dentin slabs, the micro-shear bond strength (μSBS) of each group was detected. The concentrations of cross-linked carboxyterminal telopeptide of type I collagen (ICTP) were also evaluated using an immunoassay to detect the degree of collagen degradation in each group. Results Dentin depth, adhesive treatment and storage treatment all showed significant effects on both the μSBSs and the ICTP values ( P < 0.05). Regardless of the adhesive type, thermocycling decreased the μSBSs and increased the ICTP values ( P < 0.05). The DD groups showed significantly lower μSBSs and higher ICTP values than SD groups after thermocycling aging ( P < 0.05). The treatment with Single Bond 2 significantly increased the ICTP values ( P < 0.05), whereas Clearfil S 3 Bond showed no effect on the ICTP values ( P > 0.05). Significance Deep dentin showed significantly more bond degradation after thermocycling than did superficial dentin. [ABSTRACT FROM AUTHOR]

Objectives To identify proteoglycans (PGs) and collagen fibrils (CF) within human dentin by means of a dual immunofluorescent labeling technique and to investigate the monomer infiltration of two etch-and-rinse adhesives to tosyl-phenylalanine chloromethyl-ketone (TPCK)-treated trypsin (TRY)-pretreated dentin. Methods Thirty-micrometer sections of middle coronal dentin were obtained and etched with 37% phosphoric acid gel for 15 s. After preconditioning with or without TRY digestion, the sections were subjected to dual immunofluorescent labeling and observed with a confocal laser scanning microscope (CLSM). Demineralized dentin matrixes treated with or without TRY were observed with field emission scanning electron microscope (FE-SEM). Two etch-and-rinse adhesives, Adper Single Bond 2 (SB) and Prime & Bond NT (PBNT), were applied to the dentin surfaces that were pretreated with or without TRY. The thickness of the hybrid layers was evaluated under confocal micro-Raman spectroscopy and analyzed with a two-way ANOVA. Results Green and red fluorescence was used to represent the PGs and the CF that were colocalized in the same section with different distributions. PGs were localized in the lumens of the dentin tubules and in peritubular dentin, while the type-I collagen fibrils were localized in intertubular dentin and peritubular dentin. After preconditioning with TRY digestion, the red fluorescence decreased or disappeared, the organic filaments in the lumens of the dentin tubules disappeared, the tubules were enlarged, and the hybrid layer thickness for adhesives bonded to the TRY-pretreated dentin surfaces were significantly increased ( p < 0.001 for both SB and PBNT). Significance The dual immunofluorescence labeling methodology can be used to study the human dentin matrix without decalcifying the entire dentin fragment. Proteoglycans were localized in the lumens of the dentin tubules and in peritubular dentin, which could depress the infiltration of the adhesive resin monomers. The use of TRY digestion increased the thickness of the hybrid layer created by the tested two-step etch-and-rinse adhesive. [ABSTRACT FROM AUTHOR]