جستجوی مقالات مرتبط با کلیدواژه « bond strength » در نشریات گروه « پزشکی »

 Ensuring strong adhesion of silicate-based cement to dentin during root canal therapy is crucial for achieving optimal results. This review aims to evaluate how different intracanal medicaments impact the tensile bond strength of silicate-based cement in root canal treatments.

 A thorough electronic search was performed using the PubMed and Google Scholar databases for articles published from 2000 to 2023.

 The studies included in this review evaluated the effects of various intracanal medicaments, including calcium hydroxide, chlorhexidine, triple antibiotic paste, double antibiotic paste, simvastatin, and bioactive glass, on the bond strength of silicate-based cements like mineral trioxide aggregate (MTA), Biodentine, and calcium-enriched mixture (CEM) cement. The results demonstrated varied impacts of these medicaments; some improved bond strength, while others had minimal effect. Specifically, calcium hydroxide frequently enhanced bond strength, and some antibiotic pastes showed similar benefits. In contrast, medicaments such as phenolic preparations and formaldehyde were found to have limited efficacy and potential toxicity.

 The type, concentration, and application site of intracanal medicaments significantly impact bond strength. This review highlighted the potential advantages of these medicaments, including improved root canal disinfection and enhanced push-out bond strength of commonly used dental cements. These insights can help dental professionals optimize root canal treatments and improve patient outcomes.

Establishing a strong and durable bond between cements and root canal dentin has been widely studied. Since the effectiveness of proanthocyanidin (PA) as a collagen cross-linker has been proven, the strength and durability of the bond between fiber posts and root canal dentin are expected to increase following the application of PA. Therefore, the present study aimed to assess the effect of PA pre-treatment on the bonding durability of fiber posts with three resin cements.

Ninety human single-rooted teeth with similar anatomical root shape and length were collected. After decoronation and root canal therapy, the teeth were divided into nine groups: etch and rinse (ER), self-etch (SE), self-adhesive (SA), PA pre-treatment andetch and rinse (PAER), PA pre-treatment and self-etch (PASE), PA pre-treatment and self-adhesive (PASA), chlorhexidine (CHX) pre-treatment and etch and rinse (CHXER), CHX pre-treatment and self-etch (CHXSE), and [ CHX pre-treatmentand self-adhesive (CHXSA). After microslicing the roots, push-out tests were performed immediately for half the specimens and after three months of water storage and thermocycling for the other half. Data were analyzed using two-way ANOVA and Tukey’s testwithα=0.05.

Resin cement type (P=0.001), dentin pre-treatment method (P=0.001), water storage and thermocycling (P=0.001), and the root region (P=0.001) had significant effects on bond strength.

SA resin cement had the lowest immediate and long-term bond strength in comparison with the other two cements. For ER and SE resin cements, no pre-treatment led to higher immediate and long-term bond strength. For SE and SA resin cements, PA pre-treatment inhibited the loss of bond strength in the long-term. The bond strength in the coronal region was higher than that in other regions.

The present in vitro study aimed to evaluate the effect of a 980 nm diode laser irradiation on the bond strength of fiber posts to intracanal dentine.

Twenty-four extracted human maxillary central incisors were obtained. After root canal treatment, the samples were randomly divided into two groups (n=12): In group 1, root canal dentin was subjected to diode laser irradiation (980 nm, 1W, continuous wave) whereas group 2 was considered the control group and was not irradiated. Fiber posts were cemented using resin cement. The pull-out bond strength of the fiber posts was assessed with a universal testing machine. The data were analyzed by an independent samples t-test (α=0.05).

The average fracture strength of the laser-irradiated group (90.04 ± 30.45 MPa) was significantly higher than the control group (62.95 ± 22.09 MPa; P = 0.021).

Diode laser irradiation to the root canal can increase the bond strength of fiber posts to intraradicular dentin.

This study investigated the effect of casein phosphopeptide‑amorphous calcium phosphate (CPP‑ACP) on the shear bond strength (SBS) of a universal adhesive in self-etch mode to demineralized dentin. Seventy-five dentin specimens were randomly divided into five groups (n=15) as follows: Group 1, intact dentin; Group 2, demineralized dentin receiving no remineralization agent; and Groups 3-5, demineralized dentin receiving CPP-ACP for 30, 90, and 180 seconds, respectively. All groups were bonded by Adper Single Bond Universal adhesive in self-etch mode. After 24 hours, the SBS test was conducted, and failure modes were recorded. The data were analyzed by one-way ANOVA, Tukey post-hoc test, and chi-square test at the significance level of P<0.05. The highest and lowest mean SBS values were observed in groups 1 (intact dentin: 29.58 ± 8.13 MPa) and 2 (demineralized dentin: 13.41 ± 4.85 MPa), respectively. ANOVA revealed a significant difference in SBS among the groups (P< 0.001). A pairwise comparison revealed that the SBS of demineralized groups (groups 2-5) was significantly lower than that of the intact samples (P< 0.05). Group 5, with CPP-ACP, applied for 180 seconds, showed a significantly higher SBS (20.74 ± 4.54 MPa) compared to group 2 (P< 0.05). Applying CPP-ACP paste for three minutes can increase the bond strength of the universal adhesive in self-etch mode to demineralized dentin, whereas shorter application times are not effective.

Thefinalstepofirrigationhasbeenconsideredtoofincreasethebondingstrengthoffillingmaterial to dentin. This study investigated the impact of three final -step irrigation methods on the endodonticsealer bond strength to dentin by using a micro push-out test.

Palatal roots of humanmaxillary molars were cleaned and shaped and randomly divided in six groups (n=15) according to the final-step irrigation method and the type of root canal sealer used. The solutions used for the final -step irrigationwere 17% ethylenediaminetetraacetic acid and 2.5% sodium hypochlorite, which underwent thre e

1)syringe-needle irrigation/conventional, 2) passive ultrasonic irrigation, and 3) XP-e ndo Finisher agitation. Theroot canal sealers used were: EndoSequence BC Sealer, and AH-Plus sealer. Roots were obturated with thesingle cone technique and then, cross -sectioned in 2- mm-thick slices (3 slices from each root). Push -out testwas performed on the sliced specimens (cervical, middle, and apical thirds) with a universal testing machine.Bond strength values were recorded in megapascal (MPa). Subsequently, each specimen was longitudinallysplit to verify the type of failur e. Data analysis was performed using Johnson transformation, three -way analysisof variance, Tukey’s post -hoc tests, and the partial Eta squared test.

There were significant differencesin bond strength between the sealers [AH: 4.46±2.24 and BC: 3.47±2.19 MPa (P<0.001)]; between final -stepirrigation methods [ passive ultrasonic irrigation: 4.52±2.25, XP-e ndo Finisher: 3.93±3.93 and syringe-needleirrigation/conventional: 3.37±2.51 MPa (P<0.001)], and between the root canal thirds represented by the slicedspecimens [cervical: 5.45±2.39, middle: 4.14±1.99 and apical: 2.30±1.30 MPa (P<0.001)]. The interactionbetween the variables had no significance (P>0.05).

Agitation of the final irrigating solution mayimprove the bonding of the sealer to canal walls. AH-Plus sealer had the highest bond strength. The bondstrength reduced significantly towards the apical thir

The present study aimed to evaluate the bond strength of Sure-Seal Root as a new bioceramic-based sealer, and compare it with other sealers, including an epoxy resin-based sealer (AH-Plus), zinc oxide eugenol (ZOE) and a mineral trioxide aggregate-based sealer (MTA Fillapex).

In this in vitro study, 40 extracted mandibular premolars were randomly assigned into 4 groups (n=10) according to the type of sealer applied as follows: Group 1: AH-Plus, Group 2: MTA-Fillapex, Group 3:  Sure-Seal Root, and Group 4: ZOE. The canals were prepared and obturated with gutta-percha and the corresponding sealer. The samples were sectioned into horizontal segments, and the push-out bond strength was determined using a universal testing machine at the coronal, middle, and apical root thirds. The data were analyzed by repeated measures ANOVA, and the significance level was set at P<0.05.

There were no significant differences in the push-out bond strength between groups in the coronal third (P>0.05). In the middle third, AH-Plus exhibited significantly greater bond strength compared to Sure-Seal Root and ZOE sealers (P<0.05), whereas MTA-Fillapex was not significantly different from the other groups (P>0.05). In the apical third, both AH-Plus and MTA-Fillapex showed significantly greater push-out bond strength than Sure-Seal Root and ZOE sealers (P<0.05).

AH-Plus sealer exhibited the highest and ZOE showed the lowest bond strength. Sure-Seal Root indicated promising bond strength results when compared to ZOE and MTA-Fillapex. The push-out bond strength of all sealers to dentin increased from the coronal to the apical third.

This study aimed to evaluate the effect of different recycling (also known as reconditioning) methods on the shear bond strength (SBS) of ceramic brackets. Fifty mechanically retentive polycrystalline ceramic brackets and 50 mandibular bicuspids were used in this study. The teeth were divided into 5 groups and bonded with new (group 1) or reconditioned brackets. The reconditioning methods were sandblasting (group 2), sandblasting + silane (group 3), hydrofluoric (HF) acid + silane (group 4), and Er:YAG laser (group 5). The SBS of brackets were assessed and the adhesive remnant index (ARI) scores were determined. Statistical analysis was performed using one-way ANOVA, Tukey, and chi-square tests at P<0.05. The highest SBS value was observed in brackets treated with sandblasting + silane (19.26 ± 3.30 MPa), which was comparable to both the control (19.01 ± 3.12 MPa) and sandblasting (16.98 ± 3.13 MPa) groups. Treatment with hydrofluoric acid + silane (9.46 ± 3.43 MPa) and Er:YAG laser (9.71 ± 1.23 MPa) yielded significantly lower SBS values than the other study groups (P<0.05). The highest overall ARI scores were observed in the HF acid + silane and Er:YAG laser group, indicating more adhesive remnants on the enamel surface. Sandblasting, with or without silane treatment, effectively restored the bond strength of ceramic brackets to almost initial values. Although recycling with hydrofluoric acid + silane or Er:YAG laser produced lower bond strengths, they still surpassed the clinical threshold of 7.8 MPa, making them viable options for bracket reconditioning in clinical settings.

Chemical substances used to prepare root canals and their residuals can alter dentin surface composition, affecting restorative systems bonding to dentin.

This ex vivo study evaluated the effects of different sealer removal methodsonthe micro-tensilebondstrength of dentin surfaces exposed using endodontic irrigants.

A total of 45 extracted healthy mandibular molars were sliced from the occlusal surface to expose their dentin surface and were randomly divided into three main groups (n = 15) based on the irrigants as G1: Distilled water (control), G2: Sodium hypochlorite (NaOCL) 5.25%, and G3: Chlorhexidine (CHX) 2%. AH Plus endodontic sealer, was applied to all exposed dentin surfaces. Each group was divided into four subgroups (SG) according to the sealer removal methods SG1: No root canal sealer (control), SG2: Moist cotton pellet, SG3: Ethanol 95% saturated cotton pellet, SG4: Round diamond bur. The teeth were restored using single bond plus and Z250 composite and sectioned to prepare sticks for micro-tensile bond testing. Additionally, failure patterns were investigated. Comparison between experimental groups was performed using Kruskal-Wallis H and Dunn’s post-hoc tests. The accepted significance level for all tests was P < 0.05.

A significant decrease was observed in the micro-tensile bond strength of the control group cleaned with 95% Ethanol saturated cotton pellets. In addition, the highest micro-tensile bond strength was observed in dentin cleaned through a diamond round bur and in the group irrigated with CHX. The failure modes were mainly adhesive.

Within this study’s limitations, the dentin bond strength is affected by the irrigation protocol and sealer removal method.

This study aimed to assess the effect of photodynamic therapy (PDT) on the pushout bond strength (PBS) of resin-based and calcium silicate-based endodontic sealers.

Forty single-canal teeth were assigned to four groups. After root canal preparation by the crown-down technique and smear layer removal, groups 1 and 2 served as the control group, and groups 3 and 4 underwent PDT by using a low-level diode laser as the light source and methylene blue as the photosensitizer (MB). The root canals in groups 1 and 3 were filled with AH26 sealer while the root canals in groups 2 and 4 were filled with Endoseal TCS. The samples were sectioned at 4, 8, and 12 mm from the apex tip (1mm thick slices). The PBS test was performed, and the mode of failure was determined in the coronal, middle, and apical thirds. The data were analyzed by the Kruskal-Wallis, Friedman, and Dunn tests.

No significant difference was noted in the PBS of resin-based and calcium silicate-based sealers in the apical, middle, or coronal thirds in the application of PDT (P > 0.05). The PBS of AH26 was significantly higher than that of Endoseal TCS (P < 0.05). Cohesive failure was the dominant mode of failure in the AH26 groups, while mixed failure was the dominant failure mode in the Endoseal TCS groups.

PDT had no significant effect on the PBS of resin-based and calcium silicate-based sealers.

 Indirect restorations have been employed in restorative dentistry to solve some of the drawbacks of direct restorations. The aim of this study was to evaluate the effect of different modes of a universal adhesive resin on the repair capacity of two indirect resin composites and a direct resin composite.

 Indirect composite resins (Ceramage and Gradia Plus) and a direct composite resin (Filtek Z250) were prepared in a plastic mold with a height and diameter of 2-mm and 6-mm, respectively. Composite blocks were thermocycled (5000 cycles, 5°C-55°C). Then, according to their surface treatments, composite blocks were categorized into six-groups: Group 1: ER (etch&rinse), Group 2: SE (self-etch), Group 3: Bur+ER (bur+etch&rinse), Group 4: Bur+SE (bur+self-etch), Group 5: Bur+Silane+ER (bur+silane+etch&rinse), Group 6: Bur+Silane+SE (bur+silane+self-etch), respectively. After surface treatments and adhesive application for bonding with a direct resin composite, all groups were then thermocycled before performing shear-bond-strength-test. Failure modes were evaluated using a stereomicroscope. Data were analyzed by two-way-ANOVA and Bonferroni-test (P<0.05).

The highest bond-strength values were obtained for Bur+Silane+SE groups, while the lowest values were obtained for the Bur+Silane+ER groups for all materials. Statistically significant differences were observed between the Bur+Silane+ER group and ER, Bur+ER and Bur+Silane+SE groups in Gradia Plus (P<0.05).

The self-etch-mode of the universal-adhesive and silane applications led to the increase in the repair-strength of the adhesive in the Filtek Z250 and Ceramage. The self-etch-mode of the universal-adhesive might be used to reduce adhesive-application-steps in the clinical repair procedures.

This systematic review aimed to evaluate the available scientific evidence concerning the effects of topical fluoride treatment on the bond strength of pit and fissure sealants. Prevention of dental caries is one of the crucial issues in pediatric dentistry. Pit and fissure sealant and fluoride therapies are two caries prevention procedures that may be performed in one session. However, fluoride therapy may affect the bond strength of pit and fissure sealants.

 An electronic search for in vitro studies published in English and Persian on topical fluoride therapy and the bond strength of pit and fissure sealants was performed via PubMed/ Medline, Web of Science, Google Scholar, Embase, and Scopus databases until May 2022. The articles were independently reviewed for quality by two reviewers. Textual data were analyzed manually, and the bond strength of sealants placed after fluoride application was compared with control groups.

 A total of 8482 articles were initially identified and reviewed by two independent reviewers, and 13 were selected for full-text evaluation. Finally, six articles were included in the systematic review. A total of 250 teeth were studied, 148 of which were in the case group (fluoride group) and 102 in the control group. Tensile and shear bond strengths were compared between groups in the studies.

  In the studies in which the tooth surfaces were washed after applying fluoride, there was no change in the fissure sealant bond strength. However, in studies in which fluoride was not washed, the bond strength decreased significantly, independent of the fluoride type.

The purpose of this in vitro study was to investigate the effect of incorporating silver nanoparticles (AgNPs) of herbal origin into mineral trioxide aggregate (MTA) on the push-out bond strength (PBS) and compressive strength (CS) in simulated furcal area perforations.

In this in vitro study, simulated furcal area perforations (1.3 mm in diameter and 2 mm in depth) were created in 40 extracted human lower molar teeth, which were divided into two groups (n=20): MTA alone and MTA combined with AgNPs (2% wt). Using a universal testing machine, PBS was evaluated by performing push-out tests, while CS was assessed using cylindrical specimens. The normal distribution of data was checked using the Kolmogorov-Smirnov test, and statistical analysis was performed using two-way ANOVA.

The CS results showed no significant difference between the MTA group at 4 and 21 days (P=0.297), but a significant difference was observed in the nanosilver/MTA group (P=0.013). However, there was no significant difference in the push-out bond strength among the study groups (P>0.05).

The incorporation of herbal origin silver nanoparticles did not significantly affect the PBS or CS of MTA.

The present study evaluated the effect of different surface treatments of fiber posts on the micro-push-out force between posts and various composite core materials. A total of 80 fiber posts were divided into 16 groups according to the surface treatment and core material. Four different surface treatments were applied on fiber posts including Al2O3 sandblasting, CoJet sandblasting, ytterbium-doped fiber (YbPL) laser roughening, and control (no surface treatment). The core materials were Bis Core, Core Flo, Clearfil DC Core, and Clearfil Photo Core, which were applied in a transparent mold on the surface-treated posts. The light was applied for a total period of 120 seconds. Four 1-mm sections were obtained from each post-core structure. The micro-push-out test was then performed and the results were recorded in Newtons and converted to megapascals (MPa). The type of surface treatment (P<0.001) and core material (P<0.001) significantly affected the bond strength. The highest bond strength was found in the combined application of Al2O3 sandblasting and Core Flo material (132.84 MPa) and the lowest was observed in YbPL laser-treated posts combined with Bis Core material (59.46 MPa). Among the core materials, Clearfil Photo Core showed the highest bond strength with no significant difference from the Core Flo material. Clearfil Photo Core or Core Flo may be preferred for clinical use. Among the surface treatments, sandblasting with Al2O3 showed the highest bond strength.  (J Dent Mater Tech 2023;12(2): 61-67)

This study compared the influence of various adhesive systems and silane application on the adhesion of resin-based luting cement to lithium disilicate, indirect composite resin, and zirconia restorations. Lithium disilicate (n=50), indirect composite resin (n=50), and zirconia (n=50) blocks were divided into five groups (n=10), according to the adhesive protocol applied as follows: 1. Optibond XTR, 2. silane + Optibond All in One, 3. One Coat 7 Universal, 4) Adper Scotchbond Multi-Purpose, and 5) Silane + Single Bond Universal. The blocks were bonded to a resin-based luting cement after surface treatments (silica coating and acid application). The bonded specimens were incubated in 37° C water for 24 hours and thermocycled for 5,000 cycles. The shear bond strength (SBS) was evaluated by a universal testing machine. The adhesion protocols for each type of restoration were compared by one-way ANOVA and Dunnett T3 test. There were significant differences in the bond strength of cement to indirect restorations between various adhesive protocols (P<0.05). In all types of restorations, the highest SBS was observed in group 5, which was silanized and bonded with Single Bond Universal. The bond strength of group 5 in lithium disilicate, indirect composite resin, and zirconia groups were 26.1 ± 4.9 MPa, 20.5 ± 5.7 MPa, and 15.4 ± 4.7 MPa, respectively. It appears that the best adhesive protocol for bonding cement to lithium disilicate, indirect composite resin, and zirconia restorations is the use of silane and a universal adhesive containing silane (Single Bond Universal). (J Dent Mater Tech 2023;12(2): 104-110)

The type of bonding agent and adhesive can play an important role in the bond strength of orthodontic brackets. This study measured and compared the shear bond strength (SBS) of brackets bonded with Z250 and Denu adhesives, as well as two different types of bonding agents (Single Bond and Denu Bond).

In this in vitro study, 80 intact premolars were randomly divided into four groups (20 teeth per group). The brackets were bonded to the teeth in the following order: group A: Single Bond + Z250 adhesive; group B: Denu Bond + Z250 adhesive; group C: Single Bond + Denu adhesive; and group D: Denu Bond + Denu adhesive. The SBS values were recorded using a universal testing machine, and Adhesive Remnant Index (ARI) scores were determined. The data were analyzed by ANOVA and Fisher's exact test at a significance level of 0.05.

The mean SBS values of the A, B, C, and D groups were reported as 16.66, 17.21, 14.61, and 15.91 MPa, respectively. No significant difference was found among the groups in terms of SBS and ARI scores (P=0.06 and P=0.78, respectively).

The Denu adhesive can be used as a clinical alternative to commercial adhesives, such as Z250, for bonding metal orthodontic brackets. Moreover, bonding agents and adhesives from different companies can be used simultaneously.  

This study assessed the effect of propolis and 2% chlorhexidine (CHX) on push-out bond strength of fibre post-cemented with resin cement.

This in-vitro, experimental study evaluated 36 extracted human mandibular premolars in three groups (n=12). After root canal cleaning and shaping, propolis and 2% CHX gel were applied as an intracanal medicament in groups 1 and 2, respectively. Group 3 received no medicament. The access cavity was sealed, and the teeth were incubated for one week. The root canals were obturated and post space was prepared using the #2 Angelus drill. After 72 h of incubation, the crowns were cut, and the roots were mounted in acrylic and incubated for one week. The roots were sectioned into apical, middle and coronal thirds and underwent a push-out test. Data were analyzed using ANOVA and Bonferroni and Tukey’s tests. 

 The propolis group showed maximum and minimum bond strength in the middle and coronal thirds, respectively (P>0.05). The CHX group showed the highest and the minimum bond strength in the coronal and middle thirds, respectively (P>0.05). The control group showed maximum and minimum bond strength in the middle and coronal thirds, respectively (P>0.05). The mean bond strength in the propolis group was significantly higher than the control group (P<0.05). 

using propolis as intracanal medicament can increase the push-out bond strength of fibre post-cemented with resin cement in the middle third of the root while using CHX increases the push-out bond strength of fibre post in the coronal third.

Statement of the Problem:

 Dentin margins have a higher microleakage than enamel in composite restorations due to weaker bond durability. Clinically, most margins are located apical to cementoenamel junction on the dentin or cementum. Different surface preparation methods may have dissimilar effects on the shear bond strength of resin-modified glass ionomer (RMGI) to composite resin, regarding the layering technique employed in restoration of these cavities.

This study aimed to investigate the shear bond strength of RMGI to composite resin using different mechanical surface preparation methods.

In this in vitro study, 72 RMGI samples were prepared in six groups (n=12): control, acid etching, air abrasion with aluminum oxide (Al2O3), bur, Er: YAG laser, and Er, Cr: YSGG laser groups. Two samples from each group were randomly examined under a scanning electron microscope (SEM). A bonding layer and composite resin were applied and cured. Then the samples were subjected to 5000-cycles thermocycling procedure. The shear bond strength was then evaluated using a universal testing machine. Finally, the failed surface of the samples was evaluated under a light microscope to examine the failure mode. For the statistical analysis, one-way ANOVA and Games-Howell post hoc test was used to compare quantitative variables and chi-squared test to investigate the relationship between the failure mode and the groups. The significant level was set at 0.05.

The results showed significant differences between the mean of the strength variable in the groups (p< .001). The acid-etch and air abrasion groups exhibited significantly the lowest and highest values, respectively. The chi-squared test results also showed a significant relationship between the failure mode in the study groups (p= .008).

Acid etching before completing RMGI polymerization could adversely affect shear bond strength. The air abrasion and bur methods are among the best methods to increase the shear bond strength between composite resin and RMGI. Using Er, Cr: YSGG and Er: YAG lasers could increase the bond strength results.