Mean Bond Strength Values Research Articles

Shear bond strength of cemented zirconia-reinforced lithium silicate ceramics (Celtra Duo) with two surface treatments (in vitro study)

Enhance the bonding of cement to ceramic surface with a variety of ceramic surface modifications have been established. Air-abrasion using alumina particles, hydrofluoric acid has been shown to provide micromechanical interlocking at the ceramic-resin interface. The aim of the present study was to evaluate the effect of two surface treatments; acid etching and sandblasting; on the shear bond strength of cemented newly introduced zirconia-reinforced lithium silicate ceramics following thermocycling. Methods: 24 discs of Zirconia- reinforced glass ceramics (Celtra Duo) were tested using 10% hydrofluoric acid for 20 s (control group) and 50 µm aluminum oxide for 60 s at 10 mm distance from the nozzle tip of sandblasting machine. Subsequent to the surface treatments, both groups were salinized and cemented to composites background discs using self-adhesive dual cure resin cement (BisCem). All sample were subjected to 2500 thermal cycle shear bond strength and failure mode was evaluated. The results of the t-test indicated that the bond strength value is significantly influenced by the surface treatment method. It was found that hydrofluoric acid group recorded statistically significantly higher shear bond strength mean value (10.81 MPa) than aluminum oxide sandblasting group (7.76 MPa) as indicated by t-test (t = 2.9, p = 0.0109 < 0.05). Conclusion: failure mode showed a relation between the bond strength and the failure type mixed failure showed with higher bond valves and cohesive failure accompanied with lowest bond strengthen values. The shear bond strength of zirconia reinforced lithium silicate (Celtra Duo) ceramic cemented to resin cement was affected by the type of surface treatment.

Comparison between Shear Bond Strength of Er:YAG and Er,Cr:YSGG Lasers-Assisted Dentinal Adhesion of Self-Adhering Resin Composite: An Ex Vivo Study.

(1) Background: Bonding composite to tooth structure is still evolving with a substitute for phosphoric acid being the main challenge. Lately, a self-adhering composite (SAC) was developed, promising to simplify bonding to tooth structure. Unfortunately, retention especially to dentin, was not as good as the gold standard three steps bonding system. During the last 2 decades, lasers were used to enhance shear bond strength of composite to tooth structure. However, the literature provided limited information regarding laser efficiency in the immediate, as well as the long term, adhesion success of SACs to dentin. The purpose of our study was to define the optimal irradiation conditions to improve the adhesion of self-adhering flowable resin composite to dentin exposed to Er:YAG and Er,Cr:YSGG laser irradiation. (2) Methods: Seventy-two freshly extracted human third molars, prepared to have flat dentinal surfaces, were randomly divided into three groups (n = 24) including a control group (Group 1) in which dentin was left without laser irradiation. The other two groups (Group 2 and 3) received standardized irradiation at a speed of 1 mm/second with Er:YAG (60 mJ; SSP mode = 50 μs; 10 Hz; fluency of 9.4 J/cm2; beam diameter: 0.9 mm; air 6 mL/min; and water 4 mL/min), and Er,Cr:YSGG: 1.5 W; fluency of 17.8 J/cm2; turbo handpiece with MX5 short insert; 20 Hz under air/water spray (65% air, 55% water). Self-adhering flowable resin was applied to dentin in all groups. Half of the specimens were stored in water for 24 h while the other half underwent 3000 thermal cycles. Later, all specimens received a shear bond strength test. Fracture observation was done first under a stereomicroscope then by using a scanning electron microscope. (3) Results: The mean values of shear bond strength for both laser-treated dentin groups (Er:YAG laser: 13.10 ± 1.291, and Er,Cr:YSGG: 14.04 ± 5.233) were higher than in the control group 1 (8.355 ± 2.297) before thermocycling. After thermocycling, shear bond strength decreased in all groups as follows: 10.03 ± 1.503, 10.53 ± 2.631, and 02.75 ± 1.583 for Er:YAG, Er,Cr:YSGG, and nonirradiated dentin, respectively. Shear bond strength values showed a significant difference between the control group (Group 1) and both lasers groups (Group 2 and 3). Statistical analysis of stereomicroscope observation revealed no significant difference between laser irradiation and failure mode (p < 0.136). SEM observation of the dentin surface in both laser-irradiated groups showed opened tubules, absence of smear layer as well as an increase of resin infiltration into dentinal tubules. (4) Conclusion: Er:YAG and Er,Cr:YSGG lasers enhance self-adhering flowable resin shear bond strength values and improve its longevity by eliminating the smear layer, opening dentinal tubules and increasing resin infiltration into the microstructure.

Influence of different surface treatments and universal adhesives on the repair of CAD-CAM composite resins: An in vitro study

Statement of problemThe repairability of computer-aided design and computer-aided manufacturing (CAD-CAM) composite resins might be adversely affected by the high degree of matrix polymerization that occurs during their manufacturing process. However, information on their repairability is lacking. PurposeThe purpose of this in vitro study was to evaluate the microtensile bond strength of CAD-CAM composite resins subjected to simulated repair procedures by using varying surface treatments and universal adhesives. Material and methodsFour different CAD-CAM blocks (Brilliant Crios, Lava Ultimate, Shofu Block HC, and Vita Enamic) were thermocycled (5000 times, 5/55 °C) and divided into 4 groups according to the surface treatment: control, 9% hydrofluoric acid etching, aluminum oxide airborne-particle abrasion, and tribochemical silica airborne-particle abrasion. After surface treatments, the surface roughness was measured with a nanoindenter and further examined with scanning electron microscopy. After the application of 3 different universal adhesives (Clearfil Universal Bond, Prime&Bond Universal, and Single Bond Universal), the specimens were subjected to a simulated repair process with composite resin. Bonded specimens were cut into 1 mm2 beams, and microtensile bond strength values were determined until failure at a crosshead speed of 0.5 mm/min. The bond strength data were analyzed with 3-way analysis of variance, and surface roughness data were analyzed with 2-way analysis of variance tests. Pairwise analyses were performed with the Tukey test (α=.05). ResultsAll surface treatments effectively improved repair microtensile bond strength values compared with the control (P<.05). Aluminum oxide airborne-particle abrasion had similar mean bond strength values compared with tribochemical silica airborne-particle abrasion (P>.05). Among the CAD-CAM blocks treated with hydrofluoric acid etching, Vita Enamic had the highest mean bond strength values. The highest mean microtensile bond strength repair values with the highest cohesive failure rates were found with the silane-containing universal adhesive (Single Bond Universal). ConclusionsSurface treatment with aluminum oxide airborne-particle abrasion and tribochemical silica airborne-particle abrasion produced successful repair results for aged resin nanoceramics, whereas hydrofluoric acid etching can be used for aged hybrid ceramic repair. Silane-containing universal adhesive reported increased bond strength. Application of universal adhesive after surface treatment is recommended to increase repair strength.

Effect of using Different Remineralizing Agents on Micro-shear Bond Strength of Nanohybrid Composite Resin

AIM: This study was conducted to evaluate the effect of different remineralizing agents on micro-shear bond strength (SBS) of nanohybrid composite resin to dentin.&#x0D; METHODS: Thirty-six human molars were divided into four main equal groups (nine teeth each) according to the type of remineralizing agent used; nanohydroxyapatite, sodium fluoride, fluorohydroxyapatite, and control without remineralizing agent. Each group was divided into three equal subgroups (three teeth each) according to the storage time; 1 day, 1 month, and 3 months. Specially fabricated cylindrical plastic mold was made, and teeth were embedded vertically in the mold to the level of cementoenamel junction of the tooth leaving the occlusal surface projecting above the surface of the mold. Cylindrical fissure carbide bur was used in teeth preparation. Teeth were trimmed perpendicular to the long axes of them. Demineralizing agents (Nano hydroxyapatite, sodium fluoride, and fluorohydroxyapatite) were applied then adhesive system applied then composite resin was applied using five sections of a pediatric intravenous tube to act as molds for composite specimen then the specimens stored in artificial saliva at 37°C for different storage times in an incubator. The micro-SBS was assessed using universal testing machine. Then, the mode of failure for each group was determined using stereomicroscope device. Then, the obtained data were tabulated and statistically analyzed. One-way ANOVA was used to compare between more than two non-related samples. The significance level was set at p ≤ 0.05. Statistical analysis was performed with IBM SPSS Statistics.&#x0D; RESULTS: There was statistically significant difference between the four studied groups regarding bond strength at different storage times. Fluorohydroxyapatite had the highest bond strength mean values followed by nanohydroxyapatite, while the lowest value was the sodium fluoride group.&#x0D; CONCLUSION: Fluorohydroxyapatite and nanohydroxyapatite had a positive effect on micro-SBS to dentin, but sodium fluoride had a negative effect. The storage time increase had a positive effect on the micro-SBS of dentin with fluorohydroxyapatite and nanohydroxyapatite, also it had adverse effect on the dentin bond strength with sodium fluoride and control groups.

Effect of coloring liquids on color of zirconia frameworks and bond strength of zirconia/veneering ceramic

Statement of problemZirconia substructures must be colored to fabricate esthetic restorations. However, the coloring procedure may affect the color match and bond strength of the veneering ceramic to the zirconia. PurposeThe purpose of this in vitro study was to evaluate the bond strength of veneering ceramic to zirconia after dipping in coloring liquid for different durations and to compare the color of dipped blocks with precolored blocks. Material and methodsSixty-four cube-shaped specimens were fabricated from uncolored zirconia blocks by using computer-aided design and computer-aided manufacturing and divided into 4 groups (n=16). The G30 group was subjected to coloring liquids for 30 seconds, G60 for 60 seconds, and G120 for 120 seconds. After the coloring procedures, the color of the specimens was evaluated by using a spectrophotometer. Precolored zirconia (PCZ) was used as the control. Once the color measurements were completed, the same specimens were prepared for the bond strength test, with 2 groups as the control: PCZ and the uncolored control group (control bond-strength [CBS]). Veneering ceramic was applied to the zirconia specimens and sintered. The shear bond test was conducted using universal testing equipment with a crosshead speed of 1 mm/min. Statistical analysis was carried out by using 1-way ANOVA followed by the Tukey HSD test (α=.05). A Weibull analysis was performed, and the Weibull modulus was calculated for each group. ResultsThe mean E value for the PCZ group (77.34 ±0.22) was statistically significantly different from that of all groups (PCZ-G30; P=.018, PCZ-G60; P= <.001, PCZ-G120; P<.001). The mean E value for G60 group was significantly different from mean E values of the G30 and G120 groups (G60-G30; P<.001, G60-G120; P<.001). The PCZ group had the highest mean shear bond strength value (31.5 ±7.67 MPa) and was significantly different from the mean bond strength values of the G120 and CBS groups (PCZ-G120; P=.008, PCZ-CBS; P<.001). The CBS had the lowest mean bond strength value (16.62 ±7.11 MPa) and was statistically significantly lower than that of the G60 group (CBS-G60; P=.001). The Weibull modulus was 64.78 for the PCZ group and 0.1 for the G120 group. ConclusionsImmersing zirconia in coloring liquid altered the color and negatively affected the bond strength between the veneering ceramic and zirconia.

Shear Strength of Brackets Bonded with Universal Adhesive Containing 10-MDP after 20,000 Thermal Cycles

Objectives The aim of this study was to evaluate the shear bond strength of metal brackets bonded with different universal adhesive systems containing 10-MDP and Transbond Plus Self Etching Primer after 20,000 thermal cycles. Materials and Methods. A total of 130 sound bovine teeth were used, which are divided into 5 groups (n = 26) according to the adhesive system used: All-Bond Universal (Bisco), Ambar Universal (FGM), Clearfil Universal Bond (Kuraray), Single Bond Universal (3M/ESPE), and Transbond Plus SEP (3M/ESPE) as control. The adhesives were applied for 20 seconds and bonded with a resin Transbond XT (3M/ESPE). After this, the teeth were submitted to 20,000 cycles at 5°C and 55°C. Afterwards, the shear bond strength test was performed in a universal test machine (Instron 3342). The adhesive remnant index (ARI) was evaluated under a stereomicroscope at 10x magnification and scanning electronic microscopy (SEM, Hitachi 3030). The shear bond strength data were submitted to One-Way ANOVA (α = 0.05) and the ARI to the Kruskal–Wallis test (α = 0.05) and the ARI to the Kruskal–Wallis test (Results Statistical analysis showed that the universal adhesive systems presented mean shear bond strength values similar to Transbond Plus SEP (p < 0.05). The universal adhesive presented similar ARI values among them but differed from those of Transbond Plus SEP (p < 0.05). The universal adhesive presented similar ARI values among them but differed from those of Transbond Plus SEP (Conclusions The results show that universal adhesive systems may be used for bonding metal brackets if the orthodontist wants to maintain dental enamel health.

The Effect of Aging and Surface treatments on Micro-shear Bond Strength of Resin Nano-Ceramic Material Using Two Resin Cements

Purpose: To evaluate the effect of aging and different surface treatments on micro-shear bond strength of two resin cements to resin nano-ceramic composite blocks using an in-vitro study. Materials and methods: Blocks of resin nano-ceramic (Lava Ultimate, 3M, St Paul, Minnesota, USA) were used to prepare eight plates having the following dimensions: (14mm × 12mm × 2mm). After plates preparation they were assigned to two main groups according to the surface treatment applied, either hydrofluoric acid etching and silane or sandblasting and silane. Scanning electron microscope (SEM) was used to analyze the surface topography of the Lava-Ultimate plates before and after application of surface treatments. Two resin cements were used; dual cured adhesive resin cement (Bifix QM, VOCO, Cuxhafen, Germany) and dual cured self-adhesive resin cement (Bifix SE, VOCO, Cuxhafen, Germany) to create a five resin micro-cylinders received on each lava ultimate plate. Ten specimens from each subgroup were tested after 24 hours and the other ten specimens were tested after aging in saline for 6 months. Micro-shear bond strength test was applied until failure. . Multi-factorial ANOVA test and One-way ANOVA followed by pair-wise Tukey’s post-hoc tests were used to analyze the data. Results: Both resin cements showed statistically significant decrease on bond strength after aging. Before aging, both surface treatments with adhesive resin cement showed statistically significant higher micro-shear bond strength mean values than with self-adhesive resin cement. After aging sandblasting showed a statistically significant higher micro-shear bond strength mean values with adhesive resin cement, while hydrofluoric acid etching revealed a statistically non-significant higher values with adhesive resin cement than self-adhesive resin cement. Conclusion: For both surface treatments and resin cements aging had a detrimental effect on micro- shear bond strength.

In vitro evaluation of a ceramic bracket with a laser-structured base

BackgroundThe purpose of this study was the assessment of shear bond strength (SBS), adhesive remnant characteristics, integrity of the enamel, integrity of Discovery Pearl as well as the integrity of Fascination 2 ceramic brackets following SBS testing.MethodsSixty maxillary first premolars were randomly assigned into two groups. These groups were bonded with their respective brackets. The samples underwent thermocycling (1000 cycles), SBS testing and assessment of the residual adhesive. The statistical analyses used were the independent samples t-test, the Weibull analysis and the chi-square test.ResultsThe independent samples t-test for the comparison of the mean SBS resulted in significant differences between Fascination 2 (10.50 ± 2.61 MPa) and Pearl (13.01 ± 2.50 MPa) brackets (p = 0.0003). The results of the chi-square test for ARI demonstrated a significant difference (p = 0.000) between the groups. A higher frequency of ARI scores of 2 and 3 for Pearl brackets existed. Enamel damage and bracket fracturing was not observed.ConclusionsThe mean bond strength value, the adhesive remnant characteristics, the integrity of the enamel and the ceramic brackets as well as the Weibull analyses outcomes were highly encouraging during this in vitro screening. The way is paved for an in vivo investigation with the Pearl ceramic bracket.

Analysis of surface conditioning methods on core-veneer bond strength of CAD/CAM zirconia restorations.

The increased strength of zirconia has resulted in its widespread application in clinical dentistry. Nevertheless, the fracture of veneering porcelains remains one of the key reasons of failure. The objective of this study was to compare and analyze the influence of surface conditioning methods on the core-veneer bond strength of zirconia restorations. Thirty specimens of zirconia core with sizes 10 × 5 × 5 mm were layered with porcelain of sizes 5 × 3 × 3mm. On the basis of different surface conditioning methods, four groups were made: Group I: abrasion with airborne alumina particles of 110 μm size, Group II: sandblasting with silica coated alumina particles of 50 μm in size, Group III (modified group): alteration with a coating of zirconia powder prior to sintering, and Group IV (control group): metal core specimens. The shear force of all specimens was tested using a universal testing machine with a 0.5 mm/min crosshead speed. One-way analysis of variance (ANOVA) and Tukey's post hoc pair wise comparison (p= 0.05) were performed to analyze the shear bond strength. A scanning electron microscope was used to assess the fractured specimens. A statistically significant difference was noted between the groups. The mean value of shear bond strength was 40.25 MPa for Group I, 41.93 MPa for Group II, 48.08 MPa for Group III and 47.01 MPa for Group IV. The modified zirconia group and control group demonstrated a significantly higher mean bond strength than that of Group I, where airborne particle abrasion was used. The scanning electron microscope showed that cohesive fracture in the porcelain veneers was the main problem of failure in altered zirconia. The modified zirconia specimens in Group III demonstrated significantly improved values of shear bond strength.

Shear Bond Strength at the Resin/Bracket Interface of Sandblasted Brackets with Different Aluminum Oxide Particle Size

Introduction: The aim of this study was to compare the shear bond strength at the resin/bracket interface of metal brackets sandblasted with aluminum oxide particles of 25 µm, 50 µm and 110 µm. Materials and Methods: Sixty metal brackets were recycled and randomly assigned into four groups according to the aluminum oxide (Al2O3) particle size (µm) used during sandblasting. Brackets of the first three groups (Group 1, n = 15; Group 2, n = 15 and Group 3, n = 15) were sandblasted with 25µm, 50µm, and 110µm Al2O3 particle size, respectively. The control group (Group 4, n = 15) included brackets without sandblasting. Shear bond strength was evaluated before and after sandblasting. Brackets with some variation in shape or structure were excluded. Intragroup and intergroup comparisons were performed with paired t-test and one-way analysis of variance (ANOVA) followed by Scheffe test, respectively. Results: The recycled sandblasted brackets showed greater shear bond strength approximately 4 to 6 Mpa more than those that did not receive sandblasting. There were no statistically significant differences between the sandblasted groups (P > 0.05). However, Group 3 (110µm) showed a numerically greater mean value of shear bond strength (9.34 ± 4.18 Mpa). Conclusion: Similar share bond strength at the resin/bracket interface can be expected after bracket sandblasting with 25µm, 50µm, and 110µm Al2O3 particle size. Independently of the particle size used, the sandblasted brackets showed greater shear bond strength than brackets without sandblasting.

Effects of different adhesion promoters and deproteinizing agents on the shear bond strength of orthodontic brackets: An in vitro study.

OBJECTIVE:To evaluate the effects of different adhesion promoters, namely, Enhance LC, Ortho Solo, Assure Universal Bonding Resin and deproteinizing agents such as 5.25% NaOCl, 10% papain gel on the shear bond strength of orthodontic brackets.MATERIALS AND METHOD:The present study was approved by the Ethics Committee of Teerthanker Mahaveer Dental College and Research Centre, affiliated to Teerthanker Mahaveer University, Moradabad, India. Around 150 extracted sound human upper bicuspids were taken and divided into six groups. Group 1 control (37% H3PO4), Group 2 (37% H3PO4 + Ortho Solo), Group 3 (37% H3PO4 + Assure Universal Bonding Resin), Group 4 (37% H3PO4 + Enhance LC), Group 5 (5.25% NaOCl + 37% H3PO4), and Group 6 (10% papain gel + 37% H3PO4). In all the groups (n = 150) orthodontic metal brackets were bonded with TransbondTM XT and all the samples were subjected for evaluation of shear bond strength using Instron universal testing machine at a cross speed of 0.5 mm/min. The bracket failure mode was examined using Adhesive Remnant Index (ARI). The Kruskal-Wallis test and the Mann-Whitney test were used to compare the shear bond strength. The Chi-square test was used to determine significant differences in the ARI scores among the groups. The significance for all statistical tests was P < 0.05.RESULTS:Mean values of shear bond strength showed statistically significant differences between the evaluated groups (P < 0.005). The lowest and highest shear bond strength was attributed to Group 1 (control) and Group 2 (Ortho Solo), respectively. No statistically significant difference was noted for the mean ARI scores between control, adhesion promoters, and deproteinized group (P < 0.05).CONCLUSION:It was concluded that adhesion promoters and deproteinizing agents can be used to enhance the shear bond strength of orthodontic brackets. Among all the groups Ortho Solo showed the highest bond strength when used with TransbondTM XT.

Effect of Apical Root Canal Perforation Size on Push-out Bond Strength of Glass Fiber Dowels

To evaluate in vitro effect of apical root canal perforation size on push-out bond strength of glass fiber dowels cemented to sound or perforated root canals using two different adhesive systems. A total of 120 human-extracted intact upper central incisors were selected. Teeth were sectioned 3 mm coronal to cement enamel junction, and the remaining root received endodontic root canal therapy. The roots were divided into two experimental groups according to the root condition: either sound (n = 40) or apically perforated (n = 80). Dowel spaces were prepared for all specimens to a depth of 10 mm. Roots were restored with glass fiber dowels. The experimental group was further subdivided into four subgroups (n = 20) according to the adhesive system used and apical perforation size: group I, perforated root 2 mm apically, dowel cemented using total-etch adhesive cement; group II, perforated root 2 mm apically, dowel cemented using self-etch adhesive cement; group III, perforated root 4 mm apically, dowel cemented using total-etch adhesive cement; and group IV, perforated root 4 mm apically, dowel cemented using self-etch adhesive cement. The control group, sound root, was divided into two subgroups: group I, sound root, dowel cemented using total-etch adhesive cement, and group II, sound root, dowel cemented using self-etch or total-etch adhesive cement. Each root was then cut horizontally, and root segments were prepared to be tested. The bond strength between dowel and dentin was measured with universal testing machine using a push-out test. The two-way analysis of variance (ANOVA) was used to analyze the data and post hoc Tukey's test (α = 0.05). Root canal perforation and the type of adhesive system used resulted in significant differences in push-out bond strength (p < 0.05). Regardless of root canal perforation size, glass fiber dowels in normal root canals had significantly higher mean bond strength values (9.2 ± 1.4 MPa) compared with perforated root canals (6.1 ± 1.4 MPa). Also, self-etch protocol had significantly higher mean bond strength values (9.1 ± 1.3 MPa) compared with total-etch protocol (6.2 ± 2.1 MPa). The apical root perforation size caused a direct effect on the bond strength of the glass fiber dowels cemented to dentin by reducing the bond strength values to the root dentin regardless of the adhesive system used. Prior to perforation repair, dentist or endodontist should evaluate the perforation size to predict the treatment outcome.

Influence of various airborne-particle abrasion conditions on bonding between zirconia ceramics and an indirect composite resin material

Statement of problemIndirect composite resins (ICRs) have been suggested as veneering materials for implant-supported zirconia-based fixed dental prostheses; however, obtaining a durable bond between the zirconia ceramic and the ICR is a challenge. PurposeThe purpose of this in vitro study was to evaluate the influence of airborne-particle abrasion conditions on the bond strength between 2 kinds of zirconia (yttria-stabilized tetragonal zirconia polycrystal [Y-TZP] and ceria-stabilized tetragonal zirconia/alumina nanocomposite [Ce-TZP/A]) and an ICR. Material and methodsZirconia disks were prepared by using computer-aided design and computer-aided manufacturing (CAD-CAM) systems. Specimens were airborne-particle abraded with different particle sizes (25, 50, 90, 125 μm) and jet pressures (0.1, 0.2, 0.3, 0.4 MPa). The control group (CO) was not subjected to airborne-particle abrasion. The surface roughness (Ra) of the specimens was measured. Subsequently, the specimens were treated with a primer and bonded with a light-activated composite resin, and the shear bond strength (SBS) was tested. The obtained data were analyzed by using multivariate analysis of variance, the Spearman rank-order correlation, and the Mann-Whitney U test (α=.05). After the SBS test, the interface failure modes were observed by scanning electron microscopy, and X-ray photoelectron spectroscopy (XPS) was used to analyze the chemical changes of the zirconia surface. ResultsThe Ra values increased significantly (P<.05) after airborne-particle abrasion with a positive correlation with both particle size and jet pressure. The airborne-particle abraded specimens exhibited significantly higher bond strength after thermocycling (P<.05) than the CO. Nevertheless, the bond strength was not significantly different among different airborne-particle abrasion treatments (P>.05). Additionally, Y-TZP had higher mean bond strength values than Ce-TZP/A. The XPS results revealed that after airborne-particle abrasion, the alumina particles mechanically adhered to the zirconia surface. ConclusionsWithin the limitations of this in vitro study, airborne-particle abrasion improved the bond strength between zirconia and ICR; however, particle size or jet pressure were not influencing factors.

Shear Bond Strength of Composite Resin and Conventional Flowable Composite in Primary Molars Prepared by Bond prep mode and Cutting mode Er, Cr:YSGG Laser (an in vitro study)

Introduction: Recently laser usage became popular in pediatric dentistry due to its efficiently in cutting enamel and dentin without pain, and with lesser vibration and noise, which leads to roughness in the structure of dental tissue like the etching process, which is the first indication for composite restorations cavity preparation. Due to the morphological differences and heterogeneous composition, of primary teeth compared to permanent teeth, the parameters of laser should be differently set. Materials and methods: This study was conducted to evaluate and compare the effect of bond prep mode and cutting mode of Er, Cr: YSGG laser in primary molars on shear bond strength of composite resin and conventional flowable composite using applied on flattened buccal and lingual surface on forty-eight freshly extracted sound natural deciduous molars divided into 2 groups and each group is subdivided into 2 subgroups each according to the mode of preparation: into: group 1: bond prep mode Er,Cr:YSGG laser which were further divided into: subgroup A: composite resin and subgroup B: conventional flowable composite, and group 2: cutting mode Er,Cr:YSGG which were further divided into: subgroup A: composite resin and subgroup B: conventional flowable composite. The samples were subjected to universal testing machine. Results: The mean (SD) values for shear bond strength of Bond prep and cutting modes regardless of restorative material were 22.8 (2.7) and 19.4 (2.7), respectively. Bond prep mode showed statistically significantly higher mean shear bond strength than cutting mode (P-value <0.001, Effect size = 0.296). The mean (SD) values for shear bond strength of composite resin and conventional flowable composite regardless of preparation mode were 20.7 (3.1) and 21.4 (3.3), respectively. There was no statistically significant difference between the two restorations (P-value = 0.394, Effect size = 0.017). Conclusion: The bond prep mode is better than cutting mode, Er,Cr:YSGG Laser irradiation improves shear bond stress and no significant difference between composite resin and conventional flowable composite clinically.

Evaluation of Shear-Bond-Strength of Dental Self-Adhering Flowable Resin-Composite versus Total-Etch One to Enamel and Dentin Surfaces: An In-Vitro Study.

AIM:This study aimed to assess the shear bond strength of a self-adhering flowable resin composite versus a total-etch one to different surfaces of permanent-molars.MATERIAL AND METHODS:Thirty-six sound human permanent molars were used. The teeth were embedded in acrylic blocks, such that their buccal surfaces were shown. The teeth were divided into three groups: Group I: Uncut-Enamel, Group II: Cut-enamel-surfaces with minimal-grinding and Group III: dentin-surfaces. Half of the teeth in each group were used for bonding to a self-adhering flowable resin-composite (Dyad-flow, Kerr, USA). While the other half of each group was bonded to a total-etch flowable resin-composite (Filtek™Z350-XT,3M-ESPE, USA) which necessitate etching and bonding. Teflon-mold was used for constructing resin composite cylinders (3 × 3 mm) over the buccal surfaces. The Dyad-flow was applied in the central hole of the mould placed upon tooth-surface, and then light-cured for 20 seconds. The Filtek-Z350-XT was applied similarly after etching and bonding steps. The teeth were stored in 37°C distilled water for 24 hours. The strength was measured using a universal testing machine and statistically analysed. Modes of failure were studied using digital-microscope.RESULTS:Mean values of shear bond strength for the Dyad and Filtek-Z350-XT in the uncut-enamel were 3.5 and 24.6MPa respectively, while that for cut-enamel were 4.5 and 12.7MPa respectively (Both highly statistically significant P ≤ 0.01) and in dentin were 4.3 and 6.7MPa respectively (Statistically significant P ≤ 0.05). The failure mode for Dyad was mainly adhesive (un-cut or cut-enamel 83.3% adhesive and 16.7% mixed, while in dentin 100% adhesive). While the modes of failure for Filtek-Z350-XT in enamel, either cut or un-cut, were 50% cohesive and 50% mixed, whereas in dentin 100% adhesive.CONCLUSION:Bonding of self-etch ″Dyad-flow″ flowable resin-composite was lower than the total-etch one in enamel and dentin. Thus further material improvement may be required.

In vitro evaluation of the shear bond strength and bioactivity of a bioceramic cement for bonding monolithic zirconia

Statement of problemAdhesive cementation is the most common bonding strategy for zirconia restorations. Although cementation with a bioactive luting agent has been proposed as an alternative, how the bond strength compares is unclear. PurposeThe purpose of this in vitro study was to evaluate shear bond strength after cementing a monolithic zirconia ceramic to human dentin with a bioceramic cement, compare it with a traditional cement, and evaluate its bioactive properties. Material and methodsA total of 120 dentin specimens and 120 yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) (BruxZir) cylindrical specimens were used. Zirconia and dentin specimens were randomly divided into 8 study groups (n=15) based on 2 luting cement types (a bioceramic cement or glass ionomer cement as control), 2 airborne-particle abrasion protocols (50 μm or 110 μm), and 2 water storage durations (24 hours or 30 days). After the shear bond strength test using a universal machine at a crosshead speed of 1 mm/min, fracture patterns were evaluated under a stereomicroscope and a scanning electron microscope. Strength values were statistically analyzed with a 3-factor ANOVA model (α=.05). Bioactivity was evaluated in simulated body fluid (SBF). ResultsThe control glass ionomer cement achieved significantly greater shear bond strength compared with the tested bioceramic cement. Mean bond strength values ranged from 2.52 MPa to 5.23 MPa for the bioceramic cement tested and from 4.20 MPa to 6.61 MPa for the control cement. The duration of water storage played a significant role in the bond strength, with groups stored for 30 days reaching higher bond strength values, whereas the particle size of airborne-particle abrasion did not have a significant effect. Failure types were primarily mixed. No apatite formation was recorded on the surface of the specimens even after 30 days of immersion in SBF. ConclusionsThe evaluated cement did not develop apatite in SBF, and its bond strength values were below the control glass ionomer cement.

Effect of surface conditioning methods on the microtensile bond strength of repair composite to indirect restorative materials

This study evaluated the effect of surface conditioning methods on the microtensile bond strength (µTBS) of a restorative composite to indirect restorative materials. Blocks (5 × 5 × 4 mm3) (N = 72) of (a) Zirconia (In-Ceram Zirconia, Vita) (ZR), (b) lithium disilicate glass ceramic (IPS Empress II, Ivoclar Vivadent) (LD), (c) Indirect resin composite (Gradia, GC) (GR) were fabricated (n = 24 per group) and divided randomly into three groups: 1-Control: no conditioning, 2-Silane coupling agent, 3-Hydrofluoric acid (9.5%) (HF)+silane. Each block was duplicated in resin composite. The adhesion surfaces were conditioned with airborne-particle abrasion (110 µm Al2O3 particles). Half of the conditioned blocks received no bonding and the other half one coat of bonding (ED Primer II, Kuraray). Each conditioned block was bonded to a composite block with a resin luting agent (Panavia F2.0, Kuraray). The blocks were sectioned into 1 mm2 microsticks and tested for microtensile bond strength (µTBS) (0.5 mm/min) in a μTBS testing machine. Failure types were evaluated under stereomicroscope and Scanning Electron Microscope (SEM). Data were analyzed using three-way ANOVA, Bonferroni corrected and independent sample t-tests (p < 0.05). Significant effect of the bonding (p < 0.001) and surface conditioning (p < 0.001) were observed in all groups. The highest mean bond strength values were obtained in the bonded, HF etched and silanized groups of ZR, LD and GR (12.4 ± 2.9, 28.1 ± 1.5 and 27.2 ± 2 MPa, respectively). HF acid + silane increased the repair bond values in all materials. Majority of the failure types were adhesive for ZR group, whereas HF + silane conditioned LD and GR groups presented predominantly cohesive failures in the cement.

Can Nonthermal Plasma Improve the Adhesion between Acrylic Resin for Ocular Prostheses and Silicone-Based Relining Material?

To investigate the influence of nonthermal plasma (NTP) treatment on the tensile bond strength between heat-polymerized acrylic resin for ocular prostheses and silicone reliner, with and without the use of an adhesive primer. One-hundred and sixty-four acrylic resin specimens were fabricated and randomly distributed into four groups according to the type of surface treatment: Sofreliner Primer, NTP, Sofreliner Primer + NTP, and NTP + Sofreliner Primer. Two specimens interposed with relining material (Sofreliner) formed one test sample to perform the tensile bond strength tests, before (initial) and after storage (final) in saline solution (37°C, 90 days, n = 10). Surface characterization was performed by scanning electron microscopy (SEM) and energy dispersive spectroscopy (EDS). The failure type was classified as cohesive, adhesive, or mixed. The data were analyzed statistically using the two-way ANOVA and Tukey test, as well as the chi-squared test (α = 0.05), Bonferroni correction (α = 0.005), and Spearman correlation coefficient (α = 0.05). The SEM and EDS analyses showed the presence of a thin, homogenous organic film in the groups treated with NTP. The NTP + Sofreliner Primer group presented the largest bond strength mean values in the initial period (p < 0.05). Sofreliner Primer and NTP + Sofreliner Primer groups presented the first and second largest tensile bond strength mean values in the final period (p < 0.05), respectively. NTP + Sofreliner Primer group also had the largest number of cohesive (70%, initial) and mixed (90%, final) failures. The NTP treatment performed before the primer application enhanced the bond between the acrylic resin ocular prosthesis and the Sofreliner silicone-based reliner, even after 90 days of immersion in saline solution.

Repair bond strength of composite to Er,Cr:YSGG laser irradiated zirconia and porcelain surfaces

BackgroundFracture or chipping are major concerning failures of an all-ceramic restoration. Repairing of the failure restoration using intra-oral technique is time saving and cost effective treatment modality. The present study was proposed to evaluate effect of Er,Cr:YSGG laser irradiation on shear bond strength between zirconia/porcelain and composite resin. MethodsThirty zirconia and thirty zirconia based porcelain disc shape specimens were prepared. Three different surface treatment procedure were applied the specimens. For control groups (Group ZC and PC), instruction manual of an intra-oral porcelain repair system was followed. Different pulse rates of Er,Cr:YSGG laser irradiation (short and long pulses) were applied to zirconia and porcelain surfaces for other groups (Group ZS, ZL, PS, and PL). Porcelain repair kit was used to repair specimens using standard cylindrical teflon mold (2 × 2 mm). Repair bond strength of the repaired specimens was tested using a universal testing machine. ResultsHighest mean bond strength value was observed at Group PC that was significantly higher than laser applied porcelain groups. Long pulse laser irradiation illustrated that increased mean bond strength compared to short pulse application on to the porcelain surface. Laser applied zirconia groups showed better mean bond strength than Group ZC, but differences between the groups were not statistically significant. ConclusionDifferent modes of Er,Cr:YSGG laser irradiation enhanced repair bond strength of the composite resin to zirconia, but these were not significant. Following the instruction manual for surface treatment on the porcelain surface was better method than Er,Cr:YSGG laser surface conditioning.

Effect of Dentin Desensitizers and Nd:YAG Laser Pre-Treatment on Microshear Bond Strength of Adhesive Resin Cement to Dentin

Objectives: The aim of this study was to evaluate how microshear bond strength of different adhesive resin cements are affected by dentin desensitizers application and preparation depth. Materials and Methods: One hundred and forty-four maxillary incisors were randomly divided into two groups according to dentin preparation depth (0.8 and 1 mm) and each group subdivided into four dentin desensitizers, Nd:YAG (Neodymium-doped Yttrium aluminum Garnet) laser and control groups. The dentin desensitizers used were Gluma [Glutaraldehyde/ Hydroxyethyl methacrylate (HEMA)], BisBlock (Oxalate) Vivasens-Potassium Fluoride (KF) and Admira Protect (Ormocer/HEMA), respectively. Three dual cure resin based luting cement (RelyX ARC; Variolink II and Maxcem Elite) were used to create a 0,7 mm diameter and 1 mm height cylindirical shape buid-up in tygon tubes (n=10). Micro-shear bond strength (µSBS) test was performed at a crosshead of speed of 0.5 mm/min using a Universal testing device. Then tooth surface was investigated by steromicroscope and scanning electron microscopy (SEM). Data were analyzed using Kruskal-Wallis, Mann-Whitney U and Chi-Square (X2) tests. (p = 0.05)Results: There was no statistically difference between the groups at 0.8 mm preparation depth. At 1 mm preparation dept RelyX ARC + Gluma groups’ mean bond strength value (23.96 ± 6.66 MPa) was found statistically lower according to the other groups (p&amp;lt;0.05). RelyX ARC + Laser groups’ mean bond strength value (37.33 ± 7.39 MPa) was found statistically higher according to the other groups (p&amp;lt;0.05). Conclusions: The use of desensitizing agents affected the bond strength of the resin cements to superficial dentin. Gluma desensitizer affected negatively µSBS of RelyX ARC resin cement at 1 mm depth. Application of Nd:YAG laser to superficial dentin showed positive effects to the dentin surface and bond strength. Other desensitizing agents showed no significant effects on the resin bond strength (p&amp;gt;0.05).