Effects of solvent evaporation time on immediate adhesive properties of universal adhesives to dentin

Short- and Long-Term Bond Strength Between Resin Cement and Glass-Ceramic Using a Silane-Containing Universal Adhesive

This study aimed to evaluate the effect of various silane-containing solutions on bonding between resin cement and glass ceramic after 24 hours and after six months of water storage. Glass-ceramic plaques (IPS e.max CAD) were sandblasted with aluminum oxide, etched with 10% hydrofluoric acid (HF), and divided into five “silane treatment” groups: RelyX Ceramic Primer (RCP), RelyX Ceramic Primer and Single Bond Plus (RCP+SB), Scotchbond Universal (SBU), Clearfil Ceramic Primer (CP), and no solution (HF-only control). Each group was divided into two “storage time” subgroups: 24 hours or six months in 37°C water. Eighteen resin cement cylinders (RelyX Ultimate) were bonded to each treatment group substrate (n=18) and then subjected to microshear testing. Failure mode was analyzed using scanning electron microscopy. Debond data were analyzed using a two-way analysis of variance and the Tukey post hoc test (α=0.05) as well as Weibull distributions. The factors “silane treatment,” “storage time,” (p<0.0001), and their interaction were statistically significant (p<0.0010). Group means (MPa±SD), RCP (24 hours: 27.2±3.1; six months: 18.0±4.9), and HF-only control (24 hours: 21.1±3.4; six months: 15.7±5.8) showed a reduced bond strength after six months of water storage, while RCP + SB (24 hours: 23.4±4.4; six months: 22.2±5.4), SBU (24 hours: 18.8±3.0; six months: 17.2±3.6), and CP (24 hours: 21.7±4.3; six months: 17.4±4.8) remained constant. Weibull analysis revealed that more reliable bond strengths were obtained after six months for SBU and RCP + SB. Evaluation by scanning electron microscopy revealed that all groups demonstrated hydrolytic degradation at six months of storage, but RCP + SB and SBU indicated less. Use of a separate application of silane and adhesive system improved short and long-term ceramic/resin cement bond strength.

Masking of Enamel Fluorosis Discolorations and Tooth Misalignment With a Combination of At-Home Whitening, Resin Infiltration, and Direct Composite Restorations

This clinical report illustrates a conservative technique to mask enamel discolorations in maxillary anterior teeth caused by hypomineralization associated with enamel fluorosis and subsequent direct resin composite to improve the anterior esthetics. The treatment consisted of at-home whitening with 10% carbamide peroxide gel with potassium nitrate and sodium fluoride in a custom-fitted tray to mask the brown-stained areas, followed by resin infiltration to mask the white spot areas. An existing resin composite restoration in the maxillary right central incisor was subsequently replaced after completion of the whitening and resin infiltration procedures, whereas the two misaligned and rotated maxillary lateral incisors were built up with direct resin composite restorations to provide the illusion of adequate arch alignment, as the patient was unable to use orthodontic therapy.

Influence of photoirradiation conditions on dentin bond durability and interfacial characteristics of universal adhesives

The influence of photoirradiation conditions on dentin bond durability and interfacial characteristics of universal adhesives was investigated. Universal adhesives were applied to the dentin surfaces and photoirradiated with 100 mW/cm² for 40 s, 200 mW/cm² for 20 s, and 400 mW/cm² for 10 s. A resin composite was bonded to dentin to determine shear bond strength after 24 h water storage and 30,000 thermal cycles, and water contact angle of cured adhesive were measured by the sessile drop method. Greater dentin bond strengths after 24 h water storage and 30,000 thermal cycles were achieved under these conditions at light intensity exceeding 200 mW/cm². Universal adhesives photoirradiated above 200 mW/cm² exhibited significantly higher water contact angles than those at 100 mW/cm². The results of this study suggested that the photoirradiation conditions affect the dentin bond durability and interfacial characteristics of universal adhesives even at the same total energy.

Effect of Different Protocols in Preconditioning With EDTA in Sclerotic Dentin and Enamel Before Universal Adhesives Applied in Self-etch Mode

Objectives:

The aim of this study was to investigate the effect of different protocols of 17% ethylene diamine tetra-acetic acid (EDTA) conditioning on the etching pattern and immediate bond strength of universal adhesives to enamel and sclerotic dentin.

Methods and Materials:

Forty bovine teeth with sclerotic dentin and 20 human third molars were randomly divided into eight groups resulting from the combination of the main factors surface treatment (none, two-minute EDTA conditioning manual application, 30-second EDTA manual application, 30-second EDTA sonic application) and adhesives systems (Scotchbond Universal Adhesive [SBU] and Prime & Bond Elect [PBE]). Resin-dentin and enamel-dentin bond specimens were prepared and tested under the microtensile bond strength (μTBS) and microshear bond strength (μSBS) tests, respectively. The etching pattern produced on the unground enamel and the sclerotic dentin surfaces under the different protocols and adhesive systems was evaluated under scanning electron microscopy.

Results:

For enamel, only the main factor adhesive was significant (p<0.0001), with SBU showing the highest μSBS. In sclerotic dentin, the lowest mean was observed for the group without EDTA application and the highest mean in the group with EDTA application with the sonic device for 30 seconds. Regardless of the EDTA protocol, the highest means of μTBS were observed for SBU (p<0.05).

Conclusions:

EDTA conditioning improves the bonding performance of universal adhesives in the self-etch mode on sclerotic dentin, mainly when applied for 30 seconds with the aid of a sonic device. EDTA pretreatment also improves the retentive etching pattern of enamel, but it does not result in higher enamel bond strength.

Effect of prior silane application on the bond strength of a universal adhesive to a lithium disilicate ceramic

STATEMENT OF PROBLEM

Universal adhesives combine silane and various monomers in a single bottle to make them more versatile. Their adhesive performance is unclear.

PURPOSE

The purpose of this in vitro study was to assess the effects of an additional silane application before using a universal adhesive on the adhesion between a disilicate glass ceramic and a composite resin by using a microshear bond strength test (μSBS) and fracture analysis immediately and after thermocycling.

MATERIAL AND METHODS

One hundred lithium disilicate glass ceramic disks were divided into 10 groups for bond strength testing according to the following 3 surface treatments: silane application (built-in universal adhesive or with additional application), adhesive (Adper Single Bond Plus [SB, 3M ESPE], Scotchbond Universal Adhesive [U, 3M ESPE], and mixed U with Dual Cure Activator [DCA, 3M ESPE]); or thermocycling (half of the specimens were thermocycled 10000 times). After surface treatment, 5 resin cylinders were bonded to each disk and submitted to a μSBS test. The failure mode was analyzed under a stereomicroscope and evaluated by scanning electron microscope and energy-dispersive x-ray spectroscopy. Data from the μSBS test were analyzed by 3-way ANOVA followed by the Tukey HSD post hoc test (α=.05).

RESULTS

An additional silane application resulted in a higher μSBS result for all adhesive groups (P<.05).

CONCLUSIONS

Ceramic surface treatment influenced the performance of adhesives, which may be improved with an additional silane application.

Exposed Dentin: Influence of Cleaning Procedures and Simulated Pulpal Pressure on Bond Strength of a Universal Adhesive System

Purpose

To compare various pre-treatments serving as cleaning procedures of dentin on the bond strength of resin composite promoted by a universal adhesive system applied either in the absence or presence of simulated pulpal pressure.

Materials and Methods

Prior to application of the adhesive system (Scotchbond Universal) and resin composite (Filtek Z250), ground dentin surfaces were given one of five pre-treatments either without or with simulated pulpal pressure: 1) no pre-treatment, adhesive system in “self-etch” mode, 2) phosphoric acid etching, adhesive system in “total-etch” mode, 3) polishing with pumice on prophylaxis cup, 4) air abrasion with AIR-FLOW PLUS powder, 5) air abrasion with AIR-FLOW PERIO powder; n = 20/group of pre-treatment. After storage (37°C, 100% humidity, 24 h), micro shear bond strength was measured and data analyzed with parametric ANOVA including Bonferroni-Holm correction for multiple testing followed by Student’s t tests (significance level: α = 0.05).

Results

The ANOVA found type of pre-treatment and simulated pulpal pressure to have no significant effect on dentin bond strength. The explorative post-hoc tests showed a negative effect of simulated pulpal pressure for phosphoric acid etching (adhesive system in “total-etch” mode; p = 0.020), but not for the other four pre-treatments (all p = 1.000).

Conclusion

Air abrasion with powders containing either erythritol and chlorhexidine (AIR-FLOW PLUS) or glycine (AIR-FLOW PERIO) yielded dentin bond strengths similar to no pre-treatment, phosphoric acid etching, or polishing with pumice. Simulated pulpal pressure reduced the bond strength only when the self-etch adhesive system was used in total-etch mode.

Dentin bonding performance using Weibull statistics and evaluation of acid-base resistant zone formation of recently introduced adhesives

Dentin bonding durability of recently introduced dental adhesives: Clearfil SE Bond 2 (SE2), Optibond XTR (XTR), and Scotchbond Universal (SBU) was investigated using Weibull analysis as well as analysis of the micromorphological features of the acid-base resistant zone (ABRZ) created for the adhesives. The bonding procedures of SBU were divided into three subgroups: self-etch (SBS), phosphoric acid (PA) etching on moist (SBM) or dry dentin (SBD). All groups were thermocycled for 0, 5,000 and 10,000 cycles followed by microtensile bond strength testing. Acid-base challenge was undertaken before SEM and TEM observations of the adhesive interface. The etch-and-rinse method with SBU (SBM and SBD) created inferior interfaces on the dentin surface which resulted in reduced bond durability. ABRZ formation was detected with the self-etch adhesive systems; SE2, XTR and SBS. In the PA etching protocols of SBM and SBD, a thick hybrid layer but no ABRZ was detected, which might affect dentin bond durability.

Bond strength of fiber posts to the root canal: Effects of anatomic root levels and resin cements

STATEMENT OF PROBLEM

Decementation is one of the most frequent causes of failure in the post-cement system. The bond strength in different parts of the canal may be influenced by technical and anatomic factors.

PURPOSE

The purpose of this in vitro study was to assess the effects of anatomic root levels to reach the canal and different resin cements on the bond strength of fiberglass posts along the canal.

MATERIAL AND METHODS

One hundred thirty-five roots of bovine teeth were endodontically treated, prepared with 15-mm-long post spaces and divided according to the anatomic root level: coronal (with 15-mm post space), middle (with 10-mm post space), and apical (with 5-mm post space). Fiberglass posts were luted with the cements (n=15): conventional resin cement with 3-step etch-and-rinse adhesive system (RelyX ARC/SBMP); self-adhesive resin cement (RelyX U200) and autopolymerizing resin cement with etch-and-rinse adhesive system (C&B/All-Bond 2). After 24 hours, specimens were sectioned and subjected to the push-out test. The maximum extrusion load was recorded (0.5 mm/minute, 200 N). Data were analyzed with analysis of variance (ANOVA) and the Tukey test (α=.05). Failure mode was analyzed by using multinomial logistic regression.

RESULTS

There were no significant effects of resin cements (P>.05). The bond strength at apical third was higher when the canal was reached at the apical level than at the coronal level (P=.022). When each root level was directly reached, the coronal bond strength was lower than apical (P=.001) and middle (P=.021) for all cements.

CONCLUSIONS

When the canal was reached at the coronal, medium, and apical levels, the bond strength of conventional, self-adhesive and autopolymerizing resin cements was lower in the coronal root third.

Influence of proximal box elevation on bond strength of composite inlays

OBJECTIVES

The objective of the present study was to evaluate the influence of proximal box elevation on microtensile bond strength (mTBS) of composite inlays to the proximal box floor, using either a total-etch or a self-adhesive resin cement.

MATERIALS AND METHODS

Twenty-five human molars were selected, and a class II OM (inlay) cavity preparation was performed in each tooth. Cavities were randomly assigned into four experimental groups, according to the location of the proximal cervical margin (located 1 mm below cementoenamel junction (CEJ), or with proximal box elevation with composite resin) and the resin cement used for luting (a total-etch resin cement RelyX ARC or a self-adhesive resin cement G-Cem). After 1-week water storage, samples were subjected to mTBS test. Results were analyzed by Kruskal-Wallis and Mann-Whitney U tests (p < 0.05).

RESULTS

Kruskal-Wallis revealed statistically significant differences among experimental groups (p = 0.007). Both resin cements showed similar bond strength values when cervical margin was located below CEJ. The proximal box elevation improved the bond strength of composite inlays for both resin cements. However, only for G-Cem was this improvement statistically significant.

CONCLUSIONS

The proximal box elevation improved the bond strength attained by G-Cem resin cement. For RelyX ARC, the position of the cervical margin did not affect composite inlays bond strength.

CLINICAL RELEVANCE

Proximal box elevation does not decline bond strength of composite inlays to the proximal floor when a total-etch or a self-adhesive resin cement is used.

Effect of Storage Time on Bond Strength and Nanoleakage Expression of Universal Adhesives Bonded to Dentin and Etched Enamel

PURPOSE

To investigate bond strength and nanoleakage expression of universal adhesives (UA) bonded to dentin and etched enamel.

METHODS

Extracted human third molars were sectioned and ground to obtain flat surfaces of dentin (n = 36) and enamel (n = 48). Dentin and etched enamel surfaces were bonded with one of two UAs, All-Bond Universal (ABU) or Scotchbond Universal (SBU); or a two-step self-etching adhesive, Clearfil SE Bond (CSEB). A hydrophobic bonding resin, Adper Scotchbond Multi-Purpose Bond (ASMP Bond) was applied only on etched enamel. Following each bonding procedure, resin composite blocks were built up incrementally. The specimens were sectioned and subjected to microtensile bond strength (MTBS) testing after 24 hours or one year water storage, or immersed into ammoniacal silver nitrate solution after aging with 10,000 thermocycles and observed using scanning electron microscopy. The percentage distribution of silver particles at the adhesive/tooth interface was calculated using digital image-analysis software.

RESULTS

The MTBS (CSEB = SBU > ABU, for dentin; and CSEB > ABU = SBU = ASMP Bond, for etched enamel) differed significantly between the adhesives after 24 hours. After one year, MTBS values were reduced significantly within the same adhesive for both substrates (analysis of variance, Bonferroni post hoc, p<0.05), and no significant differences were found among the adhesives for etched enamel. Silver particles could be detected within the adhesive/dentin interface of all specimens tested. Kruskal-Wallis mean ranks for nanoleakage in ABU, SBU, and CSEB were 16.9, 18.5 and 11, respectively (p>0.05).

CONCLUSIONS

In the short term, MTBS values were material and dental-substrate dependent. After aging, a decrease in bonding effectiveness was observed in all materials, with nanoleakage at the adhesive/dentin interface. The bonding of the UAs was equal or inferior to that of the conventional restorative systems when applied to either substrate and after either storage period.

Does active application of universal adhesives to enamel in self-etch mode improve their performance?

OBJECTIVES

To evaluate the effect of adhesion strategy on the enamel microshear bond strengths (μSBS), etching pattern, and in situ degree of conversion (DC) of seven universal adhesives.

METHODS

84 extracted third molars were sectioned in four parts (buccal, lingual, proximal) and divided into 21 groups, according to the combination of the main factors adhesive (AdheSE Universal [ADU], All-Bond Universal [ABU], Clearfil Universal [CFU], Futurabond U [FBU], G-Bond Plus [GBP], Prime&Bond Elect (PBE), and Scotchbond Universal Adhesive [SBU]), and adhesion strategy (etch-and-rinse, active self-etch, and passive self-etch). Specimens were stored in water (37°C/24h) and tested at 1.0mm/min (μSBS). Enamel-resin interfaces were evaluated for DC using micro-Raman spectroscopy. The enamel-etching pattern was evaluated under a field-emission scanning electron microscope (direct and replica techniques). Data were analyzed with two-way ANOVA and Tukey's test (α=0.05).

RESULTS

Active self-etch application increased μSBS and DC for five out of the seven universal adhesives when compared to passive application (p<0.001). A deeper enamel-etching pattern was observed for all universal adhesives in the etch-and-rinse strategy. A slight improvement in etching ability was observed in active self-etch application compared to that of passive self-etch application. Replicas of GBP and PBE applied in active self-etch mode displayed morphological features compatible with water droplets. The DC of GBP and PBE were not affected by the application/strategy mode.

CONCLUSIONS

In light of the improved performance of universal adhesives when applied actively in SE mode, selective enamel etching with phosphoric acid may not be crucial for their adhesion to enamel.

CLINICAL SIGNIFICANCE

The active application of universal adhesives in self-etch mode may be a practical alternative to enamel etching in specific clinical situations.