Adhesive systems: important aspects related to their composition and clinical use

Effect of Modified Triple-Layer Application on the Bond Strength of Different Dental Adhesive Systems to Dentin

The goal of this article was to assess the effect of modified triple-layer application (MTLA) in conjunction with the active bonding technique on the bond strength of four adhesive systems to dentinal substrate. The adhesives tested were Prime&Bond Universal (PBU), OptiBond Universal (OBU), OptiBond FL (OBFL), and Clearfil SE (CSE). The adhesives were applied according to the following strategies: single active application (A) and triple adhesive layer application including Active-Passive-Passive (APP); AAP; and AAA. The micro-tensile bond strength test was evaluated following 24 h or 6 months of storage. The composite-dentin interface morphology was investigated using scanning electron microscopy. The data were statistically analyzed with a significance level of α = 0.05. At 24 h of aging, all of the factors tested were not significant (p > 0.05) for CSE. For OBFL, OBU, and PBU, statistically higher values were observed for the A technique (p < 0.05). Plus, there were no significant variances between the APP, AAP, and AAA techniques (p > 0.05) for OBFL and PBU. However, for OBU, there were no significant differences between the A and AAA techniques (p > 0.05). After 6 months of aging, the A technique showed statistically higher values when compared to the other techniques (p < 0.01), except for OBFL, where the A and AAA techniques showed promising outcomes. When comparing the bond strength values of 24 h and 6 months, only for PBU, all of the techniques used resulted in bond strength stability over time (p > 0.05). Thicker adhesive layers were observed when MTLA was applied. Only the OBFL adhesive showed the formation of resin tags in all of the modalities tested. The bonding performances of the different application techniques used were material-dependent.

Comparative analysis of bonding strength between enamel and overlay of varying thicknesses following an aging test

Abstract

Background/purpose: Overlay restorations can be used clinically as a treatment option to preserve natural dentine. However, whether the residual enamel thickness and overlay thickness affect the adhesion between the restoration and tooth is still unknown. This study was to investigate effects of the overlay thickness and residual enamel thickness on bonding strength.

Materials and methods

Overlays of different thicknesses were prepared with natural teeth which had 2, 4, and 6 mm of occlusal reduction (n = 10). Specimens were subjected to 10,000 cycles in water at 5-55 °C, and finally compressive strength tests were used to evaluate the bonding strength.

Results

All groups showed good bond strength (P > 0.05). The overlay restorations of different thicknesses reduced the preparation amount by 30.3%-7.2% and significantly preserved more of the tooth structure (P < 0.005). Compared to the control group, the overlay restoration increased the marginal fitness by about 0.67-0.88 times. The thermal cycling indicated that the decrease in the maximum bearing stress was due to the aging of the ceramic itself. Therefore, the thickness of the overlay had a greater influence on the compressive strength than the bond strength.

Conclusion

Based on the above this study recommends an overlay thickness of at least 2 mm in clinical practice. The aging test confirmed that adhesion between the overlay and teeth was quite firm and stable. This shows that a stable adhesive effect of the overlay can be used as a treatment option for preserving a greater amount of a tooth's structure.

Long-Term In Vitro Adhesive Properties of Two Universal Adhesives to Dentin

The composition of universal adhesives, as well as the adhesive strategy, may influence bonding effectiveness and durability. This study aimed to evaluate the microtensile bond strength (µTBS) and nanoleakage (NL), immediately and after 6-month aging, and in situ degree of conversion (DC), of two universal adhesives (Scotchbond Universal Adhesive, SBU; Xeno Select, XEN) applied with etch-and-rinse (ER) and self-etch (SE) strategies, in comparison with a two-step SE adhesive (Clearfil SE Bond, CSE). Dentin surfaces of fifty human third molars were randomly assigned to the following adhesives: two universal adhesives, SBU and XEN, applied in ER or SE mode and CSE, used as control. Teeth were sectioned into beams to be tested under µTBS, half of them after 24 h, and the rest after 6 months of water aging. Selected beams from each tooth were used for NL evaluation and in situ DC quantification. SBU and CSE showed significantly higher mean µTBS and lower nanoleakage than XEN, regardless of the evaluation time and adhesion strategy. XEN-SE yielded the lowest degree of conversion. Therefore, adhesive properties of universal adhesives to dentin are material dependent, regardless of the adhesion strategy, exhibiting XEN a significantly worse performance than SBU.

Bond Strength and Adhesion Mechanisms of Novel Bone Adhesives

Bone adhesives offer distinct advantages over the use of screws to attached internal fixation plates (IFPs). As the chemical composition of bone is similar to dentine, it is possible that the types of monomers used to make dentine adhesives could be utilised to affix IFPs to bone. The ability to attach a bio-resorbable IFP to porcine bone was assessed for the monomer 10-methacryloyloxydecyl dihydrogen phosphate (MDP), used either as a homopolymer or a copolymer with urethane dimethacrylate (MDP + U). Additionally, the addition of a priming step (MDP + U + P) was evaluated. The chemical interactions of the monomers with bone were assessed using XRD and imaged using TEM, revealing the formation of nano-layered structures with the MDP primer, something we believe has not been reported on bone. In a 6-week artificial aging study both MDP + U and MDP + U + P demonstrated adequate shear bond strength to affix bio-resorbable IFPs. The cytotoxicity profiles of the adhesive formulations were determined using indirect and direct contact with MC3T3 cells, with indirect conditions suggesting the MDP + U + P is as cytocompatible as the resorbable IFP. The findings of this study suggest our newly developed adhesive has the potential to be used as a bone adhesive to affix bioresorbable IFPs.

Clinical in-situ evaluation of the effect of rubber dam isolation on bond strength to enamel

OBJECTIVE

To evaluate the effect of rubber dam isolation on shear bond strength of two different adhesive systems to enamel.

MATERIALS AND METHODS

The mesial, distal, lingual, and vestibular enamel surfaces of thirty human third molars were prepared (total n = 120). A custom splint was made to fit a volunteer's maxilla, holding the specimens in place in the oral cavity. Four composite resin cylinders were bonded to each tooth with one of two bonding agents (OptiBond FL and Prime&Bond active) with or without rubber dam isolation. Shear bond strength was tested in a universal testing machine and failure modes were assessed. Significance level for statistical analyses was set at 5%.

RESULTS

All pairwise comparisons revealed statistical differences (p < 0.05). The highest mean shear bond strength values were obtained in rubber dam experimental groups, regardless of the adhesive system. Group OptiBond FL with rubber dam presented the highest mean bond strength values. Fracture modes for specimens bonded without rubber dam isolation were adhesive and cohesive within enamel, while rubber dam experimental groups revealed only cohesive fractures.

CONCLUSIONS

Absolute isolation with rubber dam increases bond strength to enamel, independent of the adhesive system. The three-step total-etch system OptiBond FL provided significantly higher bond strength values than Prime&Bond active under both experimental conditions.

CLINICAL SIGNIFICANCE

Rubber dam isolation has a significant effect on bond strengths to enamel, independent of the adhesive system. Its application is, therefore, advised whenever adhesive procedures are performed. A filled three-step etch-and-rinse adhesive performed superiorly, with or without rubber dam isolation, when bonding to enamel compared to an isopropanol-based universal adhesive.

Microtensile bond strength of resin composite to dentin using different adhesive systems and directions of electric current

Thisstudy aimed to evaluate the effect of the electric current direction application on the resin composite-dentin bond strength using three adhesive systems. Human molar teeth were distributed according to the adhesive system (two-step self-etch - Clearfil SE Bond, Kuraray [CSE]; one-step self-etch - Single Bond Universal, 3M ESPE [SBU]; and two-step etch-and-rinse - Adper Single Bond 2, 3M ESPE [SB2]), electric current direction (without electric current - control, direct and reverse electric currents - 35µA), and storage time (24h - immediate and 6 months). Resin composite blocks (Filtek Z350XT, 3M ESPE) were bonded to dentin. The teeth/resin composites specimens were stored in distilled water at 37ºC for 24 hours and 6 months for the microtensile bond strength (µTBS) test (n = 10; ~12 sticks for each tooth). Failure patterns were analyzed on a stereomicroscope and classified as cohesive-dentin, cohesive-resin, adhesive or mixed. Adhesive penetration into dentin and hybrid layer formation were evaluated in a scanning electron microscope (n = 6). Data were submitted to a three-way ANOVA followed by Tukey's post hoc test (α = 0.05). There are no differences in µTBS when the adhesive systems were applied under direct and reverse electric currents, but both electric currents increased the µTBS for all adhesive systems. SBU showed the lowest µTBS values for control groups in both storage times and direct electric current in 6 months of storage. The adhesive failure pattern was more frequently observed in all groups. The electric current formed long resin tags for all adhesive systems. Storage for 6 months did not significantly decrease µTBS values. Both directions of electric current (positive and negative charges) at 35µA can increase the µTBS of the adhesive systems tested to dentin.

Comparative Assessment of Different Pre-Treatment Bonding Strategies to Improve the Adhesion of Self-Adhesive Composites to Dentin

The aim of this study is to compare the adhesive interface formed in dentin, using self-adhesive composites applied with different bonding strategies, by testing the microtensile bond strength (μTBS) and ultramorphology through the use of light microscopy. Permanent, sound human molars were randomly allocated to six experimental groups. The groups included a negative control group, where only etching was performed via EtchOnly; a positive control group where an adhesive was applied, OptiBondFL (OBFL); and an experimental group where a primer was applied using a co-curing strategy together with a composite (Primer_CoCuring). The samples were sectioned into microspecimens for μTBS (n = 8) and into 1-mm thick slabs for light microscopy using Masson’s trichrome staining protocol (n = 3). The statistical analysis included a two-way ANOVA for μTBS data and Tukey’s HSD was used as a post-hoc test (significance level of 5%; SPSS v. 26.0). The results of the μTBS revealed that the self-adhesive composite (F = 6.0, p < 0.018) and the bonding strategy (F = 444.1, p < 0.001) significantly affected the bond strength to dentin. However, their interactions were not significant (F = 1.2, p = 0.29). Etching dentin with no additional treatment revealed the lowest μTBS (VF_EtchOnly = 2.4 ± 0.8 MPa; CC_EtchOnly = 2.0 ± 0.4 MPa), which was significantly different from using a primer (VF_CoCu = 8.8 ± 0.8 MPa; CC_CoCu = 6.3 ± 1.0 MPa) or using the full adhesive (VF_OptiBondFL = 22.4 ± 0.3 MPa; CC_OptibondFL = 21.2 ± 0.4 MPa). Microscopy images revealed that the experimental Primer_CoCuring was the only group with no collagen fibers exposed to the dentin−composite interface. Overall, the use of a primer, within the limitations of this study, increased the bonding of the self-adhesive composite and provided sufficient infiltration of the collagen based on light-microscopic imaging.

Effect of Intraoral Humidity on Dentin Bond Strength of Two Universal Adhesives: An In Vitro Preliminary Study

This study investigated the effect of intraoral humidity on microtensile bond strength (μTBS) to dentin of two universal adhesives applied in self-etch (SE) mode. Forty extracted human molars were selected for this study. Dentin specimens were allocated into four groups, standardized and then bonded with two commercial multimode adhesives, according to two humidity conditions (50% relative humidity (RH) and 90% RH). Following composite resin build-up and 24 h of water storage, the μTBS of the bonded interface was analyzed. The 50% RH was higher for Scotchbond Universal (SBU) than Prime&Bond Universal (PBU), while for 90% RH, SBU had significantly lower values than PBU. With PBU, the mean bond strength was not significantly different between both humidity settings tested (p > 0.05), while for SBU, the mean bond strength was significantly different between both conditions tested (p < 0.05); μTBS was significantly higher for 50% RH than for the other group. Within the limitation of this in vitro study, it can be concluded that: 1) the bonding performance of adhesives systems depends on the humidity settings; 2) increased RH exerts a detrimental effect on the bond strength of 2-hydroxyethyl methacrylate (HEMA)-containing adhesive tested. However, this phenomenon was not observed for HEMA-free adhesive tested; 3) further research in this area is needed to investigate different adhesive systems, temperatures and humidity settings.

Customized Fiber Post Improves the Bond Strength and Dentinal Penetrability of Resin Cementation System to Root Dentin

OBJECTIVE

This study aimed to evaluate the effect of fiber post customization on the bond strength (24 hours and 6 months), resin cement thickness, and dentinal penetrability of Adper Scotchbond Multi-Purpose - RelyX ARC (AS-RA), RelyX U200 (R2), and Scotchbond Universal - RelyX Ultimate (SU-RU) cementation systems to root dentin from the cervical-, middle-, and apical-thirds of the post space.

METHODS

One hundred twenty bovine incisors were endodontically treated. After post space preparation, the roots were divided into six groups, according to the luting protocols (AS-RA, R2, SU- RU) and the type of fiber post [noncustomized post (NC) and customized post (C)]. Customization procedures were peformed using a resin composite (Z350 XT). 24 hours (n=60) or 6 months later (n=60), specimens from the cervical-, middle-, and apical-thirds of the post space were submitted to cementation system thickness measurement, bond strength evaluation, and dentinal penetrability analysis with Confocal Laser Scanning Microscopy (CLSM). Failure mode was classified as adhesive, cohesive, or mixed. Data were submitted to ANOVA and Tukey tests (α=0.05).

RESULTS

Cementation protocols with customized fiber posts presented the lowest cementation system thickness, regardless of the cementation system or post space-third (p<0.05), and the highest bond strength values (p<0.05), regardless of the third space (p>0.05), for both periods (24 hours or 6 months). The comparison of push-out bond strength values between 24 hours and 6 months showed a reduction in all groups for the cervical-third (p<0.05). For the middle-third, only noncustomized groups showed reduction (p<0.05). For the apical-third, no reduction was observed (p>0.05).

CONCLUSIONS

Anatomical customization favored both the bond strength of cements to dentin and the dentinal penetrability, but with lower cementation system thickness, regardless of cement composition and adhesive strategy.

Shear bond strengths of two newly marketed self-adhesive resin cements to different substrates: A light and scanning electron microscopy evaluation

The purpose of this in vitro study was to compare the shear bond strengths (SBSs) of two newly marketed self-adhesive resin cements (RCs) to enamel, dentin, and lithium disilicate (LiSi) glass ceramic block. Forty-eight enamel and 48 dentin substrates were obtained from sound human molars. Additionally, 6 × 7 × 5 -mm- sized 24 specimens were produced from LiSi glass ceramic blocks. The tooth specimens were randomly assigned into four groups (n = 12) according to the surface treatments: (1) G-CEM ONE (GCO), (2) G-CEM ONE Adhesive Enhancing Primer (GCO-AEP) + GCO, (3) RelyX Universal (RXU), and (4) Scotchbond Universal Plus (SUP) + RXU. LiSi specimens were randomly divided into two groups (n = 12): (1) G-MultiPrimer (GMP) + GCO and (2) SUP + RXU. Following the RC applications, all specimens were kept in 100% humidity at 37°C for 24 hr and then submitted for SBS testing in a universal testing machine (1 mm/min). Data were analyzed by Welch's, one-way analysis of variance and two independent samples t tests. The nature of failures was examined under a light microscope, and scanning electron microscopy analyses were also performed for interfaces. GCO and RXU showed similar SBS to enamel (p > .05), and the use of adhesives resulted in improved SBS (p < .05). No difference was detected between GCO-AEP + GCO and SUP + RXU. The GCO-AEP + GCO exhibited the highest SBS to dentin (p < .05), followed by GCO ≥ SUP + RXU > RXU (p < .05). There was no significant difference between SBSs of two RCs to LiSi blocks (p > .05). No cohesive failure was determined for the tested groups by light microscope. The use of adhesives prior to the application of self-adhesive RCs improved their bonding to tooth tissues. GCO demonstrated superior SBS to dentin, whereas both self-adhesive RCs generated similar SBS to enamel and LiSi glass ceramic surfaces.

Effect of diode laser-assisted bleaching on the bond strength of different adhesive systems to enamel: Interfacial SEM analysis

The aim of this study was to investigate the effectiveness of diode laser-assisted bleaching on the shear bond strength (SBS) of different adhesive systems to enamel and examine the adhesive enamel interface under scanning electron microscope (SEM). 180 incisor teeth were randomly divided into three bleaching groups: (1) Unbleached control group, (2) Opalescence Boost (OB) 40%, and (3) Diode laser-assisted LaserWhite20 (LW20) 45%. After bleaching, each group was divided into two subgroups according to waiting time: immediately or 7 days' delay. The six groups were then divided into three subgroups based on the adhesive procedure: Single Bond 2 (SB2), Clearfil SE Bond (CSB), and Clearfil Universal Bond (CUB). After adhesive procedures, composite resin cylinders were bonded to the enamel surfaces. All specimens were subjected to a SBS test after 24 hr of storage in water. Data were analysed using three-way variance analysis (p < .05). Specimens were examined under a stereomicroscope and SEM. There was a significant difference between the groups bonded immediately and 7 days after bleaching (p < .05). SB2 after 7 days showed the highest SBS values (19.24 ± 2.18), whereas CUB showed the lowest values in both bleaching treatments and control groups (10.84 ± 1.66). SEM analysis of the unbleached specimens revealed long tags and uniform hybrid layer compared OB and LW20 bleaching groups. LW20 and OB bleaching adversely affected SBS to enamel when bonded immediately. Diode laser-assisted bleaching might be an alternative option due to the short working time but delaying bonding for 7 days after bleaching may not be enough for ideal adhesion. RESEARCH HIGHLIGHTS: Bleaching agents containing high concentration hydrogen peroxide reduces the enamel bond strength of adhesive systems. Postponing composite restorations for 7 days after bleaching may not be sufficient to achieve ideal adhesion. Diode laser-assisted bleaching may be preferred as an alternative bleaching method today due to its ability to shorten the operation time and cause minimal morphological changes on the enamel surface.

Comparative study of different cytotoxicity of bonding systems with different dentin thickness on L929 cell line: An experimental study

BACKGROUND

Dentin-bonding agents should have good biocompatibility as they come into close and prolonged contact with vital dentin. The present study aimed to evaluate and compare the cytotoxicity of total etch and self-etch dentin bonding systems with two different dentin thickness on L929 cell line.

MATERIALS AND METHODS

In this in vitro study 80 Class I cavities were prepared on the occlusal surfaces. The teeth were randomly divided to two groups of 40 each based on two RDT 0.5 mm and 1.5 mm. Samples were further subdivided into four subgroups of 10. Group 1: Adper Scotch bond Multi-Purpose (SBMP), Group 2: Adper Single Bond Plus (SBP), Group 3: Adper Scotch bond SE (SSE) and Group 4: Adper Easy One (EO). Group 1 and 2 were total-etch and Group 3 and 4 were self-etch. The cavities were sealed after applying of dentin bonding. Then crowns were immersed in culture medium for 24 hours and the cytotoxicity of resultant toxic extraction was measured with 3-(4,5-Dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay in 4 serial dilutions (neat,1/2 ,1/10 ,1/100). Data were analyzed by Two-way ANOVA and t-test.

RESULTS

For all the dilutions, cytotoxicity was significantly higher with 0.5 mm remaining dentin thickness (RDT) relative to 1.5 mm RDT (P ≤ 0.05). In neat dilution for both RDTs, cytotoxicity was different among all the four dentin bondings. Expression in decreasing order of cytotoxicity was SBP > SBMP > SSE > EO for both RDTs in neat dilution (P < 0.05). For all the dilutions, cytotoxicity was significantly lower for self-etch bonding systems in comparison with total-etch bonding systems (P < 0.05).

CONCLUSION

In the present study, lower cytotoxicity was found with an increase in the dilution of toxic extract and also cytotoxicity decreased with an increased dentin thickness. The adhesive systems had degrees of cytotoxic effects on cultured L929 compared to the control, except for the EO group.

Interface between calcium silicate cement and adhesive systems according to adhesive families and cement maturation

Objectives

This study aimed to evaluate the interface between a calcium silicate cement (CSC), Biodentine and dental adhesives in terms of sealing ability.

Materials and Methods

Microleakage test: 160 standardized class II cavities were prepared on 80 extracted human molars. The cavities were filled with Biodentine and then divided into 2 experimental groups according to the time of restoration: composite resin obturation 15 minutes after Biodentine handling (D0); restoration after 7 days (D7). Each group was then divided into 8 subgroups (n = 5) according to the adhesive system used: etch-and-rinse adhesive (Prime & Bond); self-etch adhesive 2 steps (Optibond XTR and Clearfil SE Bond); self-etch adhesive 1 step (Xeno III, G-aenial Bond, and Clearfil Tri-S Bond); and universal used as etch-and-rinse or self-etch (ScotchBond Universal ER or SE). After thermocycling, the teeth were immersed in a silver nitrate solution, stained, longitudinally sectioned, and the Biodentine/adhesive percolation was quantified. Scanning electron microscopic observations: Biodentine/adhesive interfaces were observed.

Results

A tendency towards less microleakage was observed when Biodentine was etched (2.47%) and when restorations were done without delay (D0: 4.31%, D7: 6.78%), but this was not significant. The adhesives containing 10-methacryloyloxydecyl dihydrogen phosphate monomer showed the most stable results at both times studied. All Biodentine/adhesive interfaces were homogeneous and regular.

Conclusions

The good sealing of the CSC/adhesive interface is not a function of the system adhesive family used or the cement maturation before restoration. Biodentine can be used as a dentine substitute.

Effect of different cement systems and aging on the bond strength of chairside CAD-CAM ceramics

STATEMENT OF PROBLEM

The bond strength of different chairside computer-aided design and computer-aided manufacturing (CAD-CAM) restorative materials to dentin with different resin cements needs to be evaluated.

PURPOSE

The purpose of this in vitro study was to investigate the effect of 3 different cementation systems after thermal aging on the shear bond strength of different CAD-CAM materials.

MATERIAL AND METHODS

The occlusal surfaces of 63 molar teeth of similar size were removed, and 21 zirconia-reinforced lithium disilicate (Vita Suprinity-VS), 21 polymer infiltrated ceramic (Vita Enamic-VE), and 21 resin nanoceramic (GC Cerasmart-GC) rectangular specimens of 2.5 mm in thickness were obtained. The ceramics were cemented using total etch (TE), self-etch (SE), and self-adhesive (SA) cement systems. Half of the specimens were subjected to thermal aging with 5000 cycles. The shear bond strength test of all the specimens was measured. Fractured ceramic surfaces were examined by scanning electron microscopy/energy dispersive X-ray spectroscopy (SEM/EDX) analysis. The Shapiro-Wilk test, 3-way analysis of variance (ANOVA), and Fisher Least Significant Difference (LSD) tests were used to analyze the shear bond strength test data (α=.05).

RESULTS

The highest bond strength value was found in the nonthermal aged VS-TE and the lowest in the thermal aged VE-TE. Significant interaction was found between TE and SE cemented ceramics (P<.001). For specimens cemented with the SA system, significant interaction was found among ceramics with thermal aged specimens (P<.001). Thermal aging significantly decreased the mean bond strength (P<.05).

CONCLUSIONS

Differences in bond strength were observed in chairside CAD-CAM ceramics when cemented with TE, SE, and SA systems. Additionally, thermal aging significantly reduced the bond strength values of all the ceramic materials, regardless of the cementation procedure. Clinicians should consider these variables and choose the most suitable cementation systems for the material used.

Dentin Bonding and SEM Analysis of a New Experimental Universal Adhesive System Containing a Dendrimer

Due to their polymerization characteristics, hyper-branched dendrimers have lately shown to be promising candidates for use in dental materials. In this study, a new dental adhesive system was prepared, using a dendrimer derived from 2-isocyanatoethyl methacrylate (G-IEMA), and its adhesive properties were investigated. The exposed dentin was treated with four universal adhesives (UAs): SBU (Scotchbond Universal^™), FUT (Futurabond M+^™), AE1 (experimental adhesive with Bis-GMA) and AE2 (experimental adhesive with G-IEMA), using Etch & Rinse (ER) or Self Etch (SE) protocols. Composite build-ups were prepared and stored for 24 h at 37 °C in distilled water. Composite/dentin beams were prepared with cross-sectional areas of 1 ± 0.3 mm² and µTBS (Micro-tensile bond strength) test was performed at 0.5 mm/min. Failures modes were evaluated by stereomicroscopy, and bonding interfaces were observed by scanning electron microscopy (SEM). Statistical analysis of µTBS data was performed using General Linear (GLM) and Linear Mixed Models (LMM). The effect of adhesive type on µTBS was significant (p = 0.010), with AE1 presenting significantly higher µTBS than SBU (p = 0.019). No other differences between adhesives were observed. ER showed significantly better results than SE (p = 0.019), and no significant interactions between the adhesives and protocols were determined. Results obtained so far pinpoint the emergence of a new paradigm in the dental materials field, as G-IEMA can be used successfully as an alternative to Bis-GMA.

Influence of cavo superficial enamel acid-etching on the microtensile bond strength of low-shrinkage composite resin

Abstract Introduction To prevent the shrinkage stresses produced during polymerization, composite resins of low polymerization shrinkage were developed. Objective To evaluate the microtensile bond strength in class I cavities restored by acid-etching the cavosurface angle and with composite resins indicated for posterior teeth. Material and method 48 healthy molars were selected and divided into six groups (n = 8), considering that the cavosurface enamel of three groups was etched with 35% phosphoric acid. The teeth were restored with the Clearfil SE Bond adhesive system and Filtek Z350 XT, Empress Direct, and Charisma Diamond composite resins, which were light-cured for 40 seconds. After 24 hours, the teeth were taken to a cutting machine, which produced sections in the buccolingual and mesiodistal directions. This resulted in toothpicks of 0.9×0.9 mm that were taken to the universal testing machine for the microtensile bond strength test. Statistical analysis was performed with ANOVA and Tukey’s test (p < 0.05). Result There was no statistically significant difference between the groups evaluated. Conclusion Acid-etching the cavosurface angle did not affect the performance of restorations, probably due to the adhesive system used.

Comparison of shear bond strength of light cure mineral trioxide aggregate and light cure calcium hydroxide with nanofilled composite: A stereomicroscopic and scanning electron microscope analysis

OBJECTIVE

The quest for ideal pulp capping materials has given rise to the development of newer materials such as light cure mineral trioxide aggregate (MTA). The bond strength of the pulp capping materials with overlying restoration is one among the several factors that are critical for the success of vital pulp therapy. Hence, we conducted this study to evaluate and compare the shear bond strength (SBS) of light cure MTA and light cure calcium hydroxide with nanofilled composite.

MATERIALS AND METHODS

Thirty acrylic blocks each with a central hole were prepared to uniform dimensions and randomly distributed into two equal groups. In Group I, light cure MTA, and in Group II, light cure calcium hydroxide was used as pulp capping materials. After the application of adhesive system, nanofilled composites were applied onto the pulp capping material using a cylindrical plastic matrix. The SBS was tested on a universal testing machine (Instrom 3366, UK) at a crosshead speed of 0.5 mm/min. The samples were examined under stereomicroscope and scanning electron microscope to analyze different modes of failure.

RESULTS

The results were statistically analyzed using independent sample t-test. Light cure MTA attained the mean SBS of 6.54 MPa and light cure calcium hydroxide attained the mean SBS of 6.56 MPa. There was no significant difference statistically in SBS of both the materials (P < 0.05). The modes of failure were predominantly mixed failure followed by cohesive failure within the restorative material in both Group I and II.

CONCLUSION

The results of the study suggest that the SBS of light cure MTA and light cure calcium hydroxide is comparable. The modes of failure analyzed in both light cure MTA and light cure calcium hydroxide are not significantly different statistically. Hence, both materials can be successfully used as pulp capping material with nanofilled composite.

Comparação da resistência de união ao cisalhamento de dois diferentes sistemas adesivos: estudo in vitro

Objetivos: O presente estudo buscou avaliar a resistência de união ao cisalhamento de dois sistemas adesivos aplicados em diferentes quantidades de camadas em amostras de esmalte e dentina bovina. Métodos: Os fatores estudados foram os sistemas adesivos em dois níveis: Single Bond Universal e Single Bond 2. As amostras experimentais foram compostas por 30 fragmentos de esmalte bovino (n=5) e 30 fragmentos de dentina bovina (n=5) divididos aleatoriamente em 2 grupos experimentais de esmalte e dois grupos de dentina, sendo esses subdivididos em 3 modos de aplicação do sistema adesivo em 1, 2 ou 3 camadas. Resultados: Os adesivos Single Bond 2 e Single Bond Universal, quando aplicados em 1 ou 3 camadas em dentina ou esmalte apresentaram similaridade estatística (p= 0,8726). Já quando comparamos o sistema adesivo Single Bond 2 e Single Bond Universal em substrato dentinário a aplicação de 2 camadas do sistema adesivo implicam em aumento da resistência adesiva estatisticamente significante (p=0,000) para o grupo Single Bond Universal aplicado em dentina. Conclusão: O adesivo Single Bond Universal apresentou melhor resistência adesiva que o adesivo Single Bond 2 quando aplicados em duas camadas em substrato dentina. Para o substrato esmalte, ambos os sistemas adesivos são efetivos independente do número de camadas aplicadas.

Rely XTM U200 versus Rely XTM ARC: uma comparação da resistência à microtração

Resumo Introdução Os cimentos resinosos são extensivamente utilizados na fixação de restaurações indiretas de cerâmica e cerômero, sendo classificados em duas categorias: os cimentos resinosos convencionais, que não apresentam uma adesão inerente à estrutura dental e requerem o uso de um sistema adesivo e os cimentos resinosos autoadesivos, que não requerem um tratamento adesivo prévio do substrato dentário. Objetivo Avaliar a resistência de união de dois cimentos resinosos, convencional e autoadesivo, quando utilizados na cimentação de restaurações cerâmicas e ceroméricas, trazendo elementos para propiciar melhor compreensão da interação adesiva em procedimentos de cimentação com as referidas categorias de cimentos resinosos. Material e método Dentes humanos (n=20), cedidos pelo banco de dentes da Universidade Federal de Alfenas (UNIFAL), foram preparados para que cilindros de cerâmica ou de cerômero fossem cimentados utilizando-se dois tipos de cimentos resinosos (autoadesivo e convencional). Após a cimentação, 20 palitos foram obtidos e submetidos ao teste de tração, avaliando-se a força necessária para a fratura. Os valores obtidos foram submetidos à análise estatística empregando-se a análise de variância (ANOVA) e o teste de Tukey. Resultado As forças mínimas e máximas necessárias ao rompimento do cimento convencional foram superiores às mesmas requeridas para o rompimento da união promovida pelo cimento autoadesivo, bem como as medianas e as médias aritméticas, independentemente do material restaurador empregado. O teste de Tukey demonstrou que as diferenças entre os cimentos empregados são estatisticamente significantes, independentemente do material restaurador. Conclusão Os resultados deste trabalho sugerem que o material utilizado para a confecção dos corpos de prova (cerâmica ou cerômero) não influenciou na resistência à tração, sendo que o cimento convencional apresentou valores superiores de resistência.

Comparison of bond strength of a composite resin with two different adhesive systems and a resin modified glass ionomer to calcium enriched mixture

Context:

It is necessary to have a proper bond between pulp-capping agent and composite materials to maintain effective coronal seal.

Aims:

This study aims to compare the shear bond strength of a composite resin with two different adhesive systems and a resin-modified glass ionomer (RMGI) to calcium-enriched mixture (CEM).

Methods:

In this study, 30 acrylic blocks (with a central hole 4 mm diameter and 2 mm height) were prepared and filled with CEM. The blocks were divided into three groups: single bond2 (SB) with Filtek Z250, single bond universal (SBU) with Filtek Z250, and RMGI. The restorative materials were placed on the CEM, and shear bond strength was measured. Data were analyzed using one-way ANOVA and games Howell tests. P < 0.05 was considered statistically significant.

Result:

Bond strength of both composite groups to CEM showed significantly higher values than RMGI-CEM group (both P < 0.001). The type of the adhesive system( total etch or universal) had no significant effect on the bond strength of composite to CEM (P > 0.05). All the failures in composite groups were as cohesive in CEM and in RMGI group was as adhesive.

Conclusions:

Shear bond strength of composite resin to CEM cement was higher than RMGI irrespective of the type of the adhesive system. The universal bonding system is recommended for bonding of composite to CEM for ease of use.

Effect of Dentin Wetness on the Bond Strength of Universal Adhesives

The effects of dentin wetness on the bond strength and adhesive interface morphology of universal adhesives have been investigated using micro-tensile bond strength (μTBS) testing and confocal laser scanning microscopy (CLSM). Seventy-two human third molars were wet ground to expose flat dentin surfaces. They were divided into three groups according to the air-drying time of the dentin surfaces: 0 (without air drying), 5, and 10 s. The dentin surfaces were then treated with three universal adhesives: G-Premio Bond, Single Bond Universal, and All-Bond Universal in self-etch or etch-and-rinse mode. After composite build up, a μTBS test was performed. One additional tooth was prepared for each group by staining the adhesives with 0.01 wt % of Rhodamine B fluorescent dye for CLSM analysis. The data were analyzed statistically using ANOVA and Tukey's post hoc tests (α = 0.05). Two-way ANOVA showed significant differences among the adhesive systems and dentin moisture conditions. An interaction effect was also observed (p < 0.05). One-way ANOVA showed that All-Bond Universal was the only material influenced by the wetness of the dentin surfaces. Wetness of the dentin surface is a factor influencing the micro-tensile bond strength of universal adhesives.

Clinical Performance of Different Solvent-based Dentin Adhesives With Nanofill or Nanohybrid Composites in Class III Restorations: Five Year Results

Purpose:

To evaluate the clinical performance of water, acetone, ethanol, and ethanol-water solvent-based dentin adhesives with nanofill or nanohybrid composites in Class III restorations.

Methods and Materials:

A total of 22 patients aged between 14 and 48 years (mean age: 25.2 years) participated in the study. Each patient received four Class III restorations, which were performed using water (Scotchbond Multipurpose), acetone (Prime&Bond NT), ethanol (XP Bond) and ethanol-water (Xeno V) solvent-based dentin adhesive systems with a nanofill (Filtek Supreme XT) or nanohybrid composite (CeramX Duo). Two experienced examiners evaluated the restorations with regard to retention, color match, marginal discoloration, wear/loss of anatomic form, caries formation, marginal adaptation, and surface texture at baseline and at one-, two-, three-, four-, and five-year recalls.

Results:

The five-year survival rates were 100% for Scotchbond Multipurpose, Prime&Bond NT, and XP Bond and 81.2% for Xeno V–bonded restorations. Only three Xeno V–bonded restorations failed. With the exception of marginal discoloration, there were no statistically significant differences among the four adhesive-bonded restorations in any of the evaluation periods in terms of the evaluation criteria.

Conclusions:

With the exception of marginal discoloration and marginal integrity deterioration of Xeno V–bonded restorations, all four adhesive-bonded restorations exhibited good long-term results. However, adhesion strategy (such as self-etch or etch-and-rinse) is more important than the solvent content of dentin adhesive systems in the success of Class III restorations.

The effect of acrylate-based dental adhesive solvent content on microleakage in composite restorations

Background:

This study aimed to evaluate the effect of different percentages of ethanol solvent of an experimental methacrylate-based dentin bonding agent containing polyhedral oligomeric silsesquioxanes (POSS) on the microleakage of resin composite restorations.

Materials and Methods:

In this experimental study, 42 extracted human premolar teeth used and 84 standard Class V cavities were prepared on the buccal and lingual surfaces of the teeth. The teeth were divided into 6 groups of 7. Experimental bonding agents with different percentages of solvent were used in 5 groups and Single Bond^® as a control. The teeth were restored with resin composite and subjected to thermal cycling test. Teeth were then immersed in a solution of 2% basic fuchsine dye for 24 h and sectioned buccolingually and scored using stereomicroscope with ×32 magnification. Microleakage data were analyzed using the Kruskal–Wallis, Mann–Whitney U, and Wilcoxon tests.

Results:

There were significant differences between the microleakage enamel margins (P = 0.036) and dentinal margins (P = 0.008) in all the groups. These significant differences were seen between the control group and groups containing 46 wt% solvent (P = 0.011), 46 wt% and 31 wt% solvent in dentinal (P = 0.027), 31 wt% and 0 wt% in enamel (P = 0.021), also 0 wt% and control in enamel (P = 0.039), and dentinal margins microleakage (P = 0.004). The microleakage in dentinal margins was higher than enamel margins (P < 0.001). In the groups with 46 wt% solvent (P = 0.103), 0 wt% (P = 0.122), and control group (P = 0.096), however, this difference was not significant.

Conclusion:

The adhesive containing 31 wt% solvent showed the least marginal microleakage, presence of POSS filler may also result in the reduction of microleakage.

Shear bond strength of a novel light cured calcium silicate based-cement to resin composite using different adhesive systems

The shear bond strength (SBS) of TheraCal LC to resin composite was evaluated in comparison to Mineral trioxide aggregate (ProRoot MTA) and conventional glass ionomer cement (GIC) using two adhesive systems. A hole was prepared in 90 acrylic blocks (6 mm diameter, 2 mm deep) then filled with TheraCal LC, MTA or Fuji IX (n=30/group). Each group was bonded with either an etch and rinse or 1-step self-etch adhesive. Filtek Z250 composite was bonded to each capping material. Bond strength was tested in a universal testing machine, and data were analyzed using 2-way ANOVA and Duncan's Multiple range test (p<0.05). TheraCal LC displayed the highest SBS (p<0.001). MTA bonded with the 1-step self-etch adhesive showed the lowest SBS (p<0.001), while SBS of TheraCal LC and Fuji IX did not differ between either adhesive (p>0.05). TheraCal LC is the preferred choice in pulp capping procedures when using resin composite restorations.

Evaluating the shear bond strength of enamel and dentin with or without etching: A comparative study between dimethacrylate-based and silorane-based adhesives

BACKGROUND

Silorane-based composites and their specific self-etch adhesive were introduced to conquest the polymerization shrinkage of methacrylate-based composites. It has been shown that additional etching of enamel and dentin can improve the bond strength of self-etch methacrylate-based adhesives but this claim is not apparent about silorane-based adhesives. Our objective was to compare the shear bond strength (SBS) of enamel and dentin between silorane-based adhesive resin and a methacrylate-based resin with or without additional etching.

MATERIAL AND METHODS

40 sound human premolars were prepared and divided into two groups: 1- Filtek P60 composite and Clearfil SE Bond adhesive; 2- Filtek P90 composite and Silorane adhesive. Each group divided into two subgroups: with or without additional etching. For additional etching, 37% acid phosphoric was applied before bonding procedure. A cylinder of the composite was bonded to the surface. After 24 hours storage and 500 thermo cycling between 5-55°C, shear bond strength was assessed with the cross head speed of 0.5 mm/min. Then, bonded surfaces were observed under stereomicroscope to determine the failure mode. Data were analyzed with two-way ANOVA and Fischer exact test.

RESULTS

Shear bond strength of Filtek P60 composite was significantly higher than Filtek P90 composite both in enamel and dentin surfaces (P<0.05). However, additional etching had no significant effect on shear bond strength in enamel or dentin for each of the composites (P>0.05). There was no interaction between composite type and additional etching (P>0.05). Failure pattern was mainly adhesive and no significant correlation was found between failure and composite type or additional etching (P>0.05).

CONCLUSIONS

Shear bond strength of methacrylate-based composite was significantly higher than silorane-based composite both in enamel and dentin surfaces and additional etching had no significant effect on shear bond strength in enamel or dentin for each of the composites. The mode of failure had no meaningful relation to the type of composite and etching factor.

KEY WORDS

Shear bond strength, adhesive, composite resin, silorane, methacrylate.

Effect of different monomer-based composites and acid etching pre-treatment of enamel on the microleakage using self-etch adhesives systems

OBJECTIVE

To evaluate quantitatively the marginal microleakage of restorations carried out with self-etching adhesives with or without prior phosphoric enamel acid etching of silorane or methacrylate resin-based composite restorations subjected to thermal cycling.

MATERIALS AND METHODS

Forty cavities were prepared at the proximal surface of bovine incisors and randomly divided according to the etching of the enamel and restorative system used. The groups were restored with methacrylate [Adper SE Plus adhesive (3M ESPE) + Filtek Z250 (3M ESPE)] or silorane [Filtek LS adhesive (3M ESPE) + Filtek LS composite (3M ESPE)] restorative systems, light-cured using a LED unit (Bluephase 16i, Vivadent). After restorative procedure and thermocycling (1000 cycles), the specimens were immersed in methylene blue for 2 h. The specimens were triturated and the powder was used for analysis in an absorbance spectrophotometer. Data were statistically analyzed by 2-way ANOVA (alpha = 0.05).

RESULTS

No statistical difference between the restorative materials tested with or without previous acid etching of enamel in Class II marginal microleakage was observed (p > 0.05).

CONCLUSIONS

The use of acid etching prior to self-etching adhesives did not interfere on the microleakage of methacrylate- or silorane-based restorations.

Effect of Bioactive Glass air Abrasion on Shear Bond Strength of Two Adhesive Resins to Decalcified Enamel

OBJECTIVE

Bioactive glass air abrasion is a conservative technique to remove initial decalcified tissue and caries. This study examined the shear bond strength of composite resin to sound and decalcified enamel air-abraded by bioactive glass (BAG) or alumina using etch-and-rinse and self-etch adhesives.

MATERIALS AND METHODS

Forty-eight permanent molars were root-amputated and sectioned mesiodistally. The obtained 96 specimens were mounted in acrylic resin; the buccal and lingual surfaces remained exposed. A demineralizing solution was used to decalcify half the specimens. Both sound and decalcified specimens were divided into two groups of alumina and bioactive glass air abrasion. In each group, the specimens were subdivided into two subgroups of Clearfil SE Bond or OptiBond FL adhesives (n=12). Composite resin cylinders were bonded on enamel surfaces cured and underwent thermocycling. The specimens were tested for shear bond strength. Data were analyzed using SPSS 16.0 and three-way ANOVA (α=0.05). Similar to the experimental groups, the enamel surface of one specimen underwent SEM evaluation.

RESULTS

No significant differences were observed in composite resin bond strength subsequent to alumina or bioactive glass air abrasion preparation techniques (P=0.987). There were no statistically significant differences between the bond strength of etch-and-rinse and self-etch adhesive groups (P=1). Also, decalcified or intact enamel groups had no significant difference (P=0.918). However, SEM analysis showed much less enamel irregularities with BAG air abrasion compared to alumina air abrasion.

CONCLUSION

Under the limitations of this study, preparation of both intact and decalcified enamel surfaces with bioactive glass air abrasion results in similar bond strength of composite resin in comparison with alumina air abrasion using etch-&-rinse or self-etch adhesives.

Comparative evaluation of the bonding efficacy of sixth and seventh generation bonding agents: An In-Vitro study

AIMS

To compare the shear bond strength of sixth generation and seventh generation bonding agents to dentin.

MATERIALS AND METHODS

EIGHTY HUMAN MAXILLARY PREMOLARS WERE REDUCED TO EXPOSE FLAT SURFACE OF DENTIN AND DIVIDED INTO FOUR EQUAL GROUPS, WHICH WERE BONDED USING FOLLOWING BONDING AGENTS: Sixth generation bonding agents, Adper SE Plus and Xeno III and Seventh generation bonding agents, Adper Easy One and Xeno V. Composite cylinders were then built using a plastic mould on these prepared dentinal surfaces. Samples were stored in distilled water for 24 hours and tested for shear bond strength with universal testing machine. Shear force was applied perpendicular to the long axis of composite cylinder at adhesive-tooth interface until debonding occurred. The data so obtained were tabulated and analyzed statistically using independent-samples t test and analysis of variance (ANOVA) test.

RESULTS

The seventh generation adhesives showed significantly higher shear bond strength to dentin compared to sixth generation adhesives (P < 0.01). The highest value of shear bond strength was obtained from Adper Easy One system, while Adper SE Plus gave the lowest shear bond strength values.

CONCLUSIONS

Seventh generation adhesives are more advantageous than sixth generation adhesives in dentin bonding as it requires less time, fewer steps, and better bond strength.

Six-month evaluation of a resin/dentin interface created by methacrylate and silorane-based materials

OBJECTIVES

This study aimed to compare the micro-tensile bond strength of methacrylate resin systems to a silorane-based restorative system on dentin after 24 hours and six months water storage.

MATERIAL AND METHODS

The restorative systems Adper Single Bond 2/Filtek Z350 (ASB), Clearfil SE Bond/Z350 (CF), Adper SE Plus/Z350 (ASEP) and P90 Adhesive System/Filtek P90 (P90) were applied on flat dentin surfaces of 20 third molars (n=5). The restored teeth were sectioned perpendicularly to the bonding interface to obtain sticks (0.8 mm2) to be tested after 24 hours (24 h) and 6 months (6 m) of water storage, in a universal testing machine at 0.5 mm/min. The data was analyzed via two-way Analysis of Variance/Bonferroni post hoc tests at 5% global significance.

RESULTS

Overall outcomes did not indicate a statistical difference for the resin systems (p=0.26) nor time (p=0.62). No interaction between material × time was detected (p=0.28). Mean standard-deviation in MPa at 24 h and 6 m were: ASB 31.38 (4.53) and 30.06 (1.95), CF 34.26 (3.47) and 32.75 (4.18), ASEP 29.54 (4.14) and 33.47 (2.47), P90 30.27 (2.03) and 31.34 (2.19).

CONCLUSIONS

The silorane-based system showed a similar performance to methacrylate-based materials on dentin. All systems were stable in terms of bond strength up to 6 month of water storage.

One-Year Evaluation of a Simplified Ethanol-Wet Bonding Technique: A Randomized Clinical Trial

The objective of this randomized clinical trial was to evaluate the clinical performance of adhesive restorations using a three-step etch-and-rinse adhesive (TSER), a one-step self-etching adhesive (OSSE), and a simplified ethanol-wet bonding technique (EWBT) prior to the application of a composite resin in non-carious cervical lesions. Ninety-three restorations (31 for each group) were placed in 17 patients by a single operator. No cavity preparation was performed. After 6 and 12 months, the restorations were assessed by two previously trained examiners using modified Ryge criteria for retention (kappa=1.00) and marginal adaptation/staining (kappa=0.81), and the results were analyzed by Fisher's exact and Kruskal-Wallis tests, respectively. No significant differences were observed among groups at the 6- and 12-month time points for any of the assessed criteria (p≥0.05). The intra-group analysis performed by Cochran's test (for retention) and Wilcoxon test (for marginal adaptation/staining) revealed significant differences between the baseline/12-month time intervals in marginal adaptation in OSSE (p=0.0180) and in marginal staining in TSER (p=0.0117). The survival analysis for retention criteria performed using a log-rank test did not show significant differences (p>0.05). The restorations placed using the simplified EWBT performed equally well as the other adhesive strategies employed.

Micro-shear bond strength of adhesive resins to enamel at different relative humidity conditions

This study tested whether exhaled humid conditions would affect the adhesion of etch-and-rinse, two-step and one-step self-etch adhesive resins to enamel. Enamel surfaces of human maxillary anterior teeth (N=240, n=20) were exposed to four humid conditions (H1: 63-68%, H2: 73-78%, H3: 93-98%, H4: 36-45% RH) during bonding with Adper Single Bond 2 (SB2), Clearfil SE Bond (CSE) and Adper Easy Bond (AEB). Specimens were stored in distilled water at 37 ºC for 24 h and tested to failure using micro-shear bond strength (μSBS) test. Data were analyzed using two-way ANOVA and Tukey's test (p<0.05). The μSBS to enamel with SB2, CSE and AEB was not significantly affected by humidity parameters. AEB resulted in significantly lower μSBS in all conditions. The frequency of adhesive failures was the highest at H2, H3 for SB2, H3 for CSE and H1-4 for AEB indicating that humidity conditions may decrease adhesion quality to enamel.

Marginal adaptation of class V composite restorations submitted to thermal and mechanical cycling

Objective:

This study evaluated the effect of the margin location and an adhesive system on the marginal adaptation of composite restorations.

Material and Methods:

Class V cavities were prepared in bovine teeth with the gingival margin on the dentin and the incisal margin on the enamel. The cavities were restored with a micro-hybrid composite resin using an etch-and-rinse [Single Bond 2 (SB)] or a self-etching adhesive [Clearfil SE Bond (CL)]. After finishing and polishing the restorations, epoxy replicas were prepared. The marginal adaptation was analyzed using scanning electronic microscopy (SEM, 500 x magnification). The higher gap width in each margin was recorded (T0). After the first evaluation, the samples were submitted to thermal cycling (2,000 cycles of 5ºC±2ºC followed by 55ºC±2ºC - T1) and mechanical cycling (100,000 cycles of 50 kN and 2 Hz - T2). Replicas of samples were rebuilt after each cycling and analyzed under SEM. The data were submitted to Mann-Whitney, Wilcoxon and Friedman testing (a=0.05).

Results:

The SB presented higher gaps in the dentin than the enamel, while there was no difference between the substrate for the CL. In the dentin, the CL showed better marginal sealing than the SB. The opposite occurred in the enamel. There were no significant differences between the baseline, thermal and mechanical cycling for any experimental condition.

Conclusions:

The outcomes of the present study showed that the adhesive system and margin location have an important effect on the marginal adaptation of composite restorations.

Restoration of endodontically treated teeth with major hard tissue loss--bond strength of conventionally and adhesively luted fiber-reinforced composite posts

AIM

To evaluate the influence of the luting system on the pull-out bond strength of conventionally and adhesively luted fiber-reinforced composite posts (FRCPs).

MATERIAL AND METHODS

One hundred extracted bovine teeth (Di 3) were endodontically treated and randomly assigned to nine test groups and one control group (n = 10) according to luting system. After preparing the post cavities (8 mm), the custom-made FRCPs were inserted using conventional glass-ionomer cement (Ketac Cem), resin-reinforced glass-ionomer cement (Meron Plus and Fuji Plus), self-adhesive resin cement (RelyX Unicem and BisCem), self-conditioning adhesive and resin cement [Multilink Primer + Multilink and AdheSE + DC Activator + MultiCore Flow, or etch-and-rinse adhesive and resin cement (SealBond Ultima + CoreCem, and LuxaBond + LuxaCore Z). As a control, custom-made titanium posts were inserted with Ketac Cem. After water storage (37°C, 24 h, dark), the pull-out test was performed, followed by failure mode evaluation. The data were statistically analyzed (α = 0.05) using analysis of variance and the Dunnett T3 post hoc test.

RESULTS

Luting system type and identity significantly influenced bond strength (P < 0.001); the bond strengths of all luting systems except Ketac Cem, MeronPlus, and BisCem were significantly higher than the control (4.4 ± 1.1 MPa). RelyX Unicem (12.0 ± 3.0 MPa) and LB + LCZ (14.8 ± 2.3 MPa) generated the highest bond strengths. The clinical application was demonstrated by restoring a traumatized tooth with extensive coronal destruction and thin root canal walls, using a FRCP combined with direct composite build-up.

CONCLUSION

Luting system selection significantly influenced the bond strength of conventionally and adhesively luted FRCPs to bovine root canal dentin.

Bond strength of adhesive systems to mineral trioxide aggregate with different time intervals

INTRODUCTION

The aim of this study was to compare the shear bond strengths of various adhesive systems to white mineral trioxide aggregate (WMTA) with different time intervals.

METHODS

Two hundred cylindrical acrylic blocks with a hole (4-mm diameter and 2-mm height) were prepared. The holes were filled with WMTA, and the specimens were allocated into 5 groups. Forty specimens were stored for 4, 24, 48, 72, and 96 hours at 37°C and 100% humidity. Each group was divided into 4 subgroups: group 1, All-Bond SE (Bisco Inc, Schaumburg, IL); group 2, All-Bond 3 (Bisco Inc); group 3, One-Step Plus (Bisco Inc); and group 4, control. After the application of adhesive systems, composite resin (Aelite, Bisco) was applied over the WMTA. Shear bond strengths were measured using a universal testing machine, and the data were subjected to 1-way analysis of variance and the Scheffé post hoc test.

RESULTS

There was a significant difference between the 4-, 24-, 48-, 72-, and 96-hour measurements in all of the adhesive systems (P < .001). Among all time intervals, group 3 showed significantly higher bond strengths to WMTA than the other groups (P < .001). Groups 1 and 2 were similar (P = .365).

CONCLUSIONS

It was concluded that if a longer waiting time can be practiced after the mixing of WMTA, higher shear bond strength measurements can be obtained. Also, when WMTA was used with total-etch adhesive systems, it showed better shear bond strength.

Effects of resin luting agents and 1% NaOCl on the marginal fit of indirect composite restorations in primary teeth

Objective

The purpose of this study was to provide information regarding the marginal adaptation of composite resin onlays in primary teeth previously treated with 1% sodium hypochlorite (NaOCl) (pulp irrigant) using two different resin luting agents.

Material and Methods

Forty extracted sound primary molars had their crowns prepared in a standardized machine and were randomly divided into 4 groups (n=10): G1 (1% NaOCl irrigation+EnForce); G2 (EnForce); G3 (1% NaOCl irrigation+Rely X); G4 (Rely X). The onlays were made with Z250 composite resin on plaster models. After luting, the tooth/restoration set was stored in 100% relative humidity at 37ºC for 24 h and finished with Soflex discs. Caries Detector solution was applied at the tooth/restoration interface for 5 s. The specimens were washed and four digital photos of each tooth were then taken. The extents of the gaps were measured with Image Tool 3.0 software. The percentage data were submitted to a Kruskal-Wallis test (α=0.05). The Relative Risk test analyzed the chance of a gap presence correlated to each group.

Results

There were no statistically significant differences (p>0.05) among the groups. The relative risk test revealed that some groups were more apt to have a presence of gaps than others.

Conclusion

Neither the 1% NaOCl treatment nor the resin luting agents caused any alterations in the dental substrate that could have influenced the marginal adaptation of composite onlays in primary teeth.