Maximum Shear Bond Strength Research Articles

A comparitive evaluation of the shear bond strength of Er:YAG laser ablation on enamel at 3 different power outputs with that of onventional acid etching technique - An invitro study

The aim of this study is to determine whether bonding of stainless steel orthodontic brackets to tooth enamel prepared by laser etching would result in a similar bonding capability as those prepared by acid etching using 37 % phosphoric acid; and also to compare the shear bond strength.Eighty four samples were prepared for the study. The 4 groups were Group 1- The enamel was etched with 37 % phosphoric acid, Group 2- Er: YAG laser etching was done at 1W power output, Group 3- Er: YAG laser etching was done at 2W power output and Group 4- Er:YAG laser etching was done at 3W power output. All groups have 20 teeth for shear bond strength testing and one tooth for SEM evaluation. Shear bond strength testing was performed on all teeth using Instron universal testing machine.Analysis of the variance indicated a significant difference (P < 0.005) among the groups. Maximum shear bond strength was shown by laser etching at 2 W to the tooth surface for 15 seconds in compared to conventional acid etching. In this study the highest shear bond strength was found in the 2-W laser etched group (16.09±0.42) MPa, followed by the 1-W laser etched group (12.62± 0.35) MPa, 3-W laser etched group( 12.01±0.31) MPa and acid etched group.(6.42±0.32)MPa.The results showed that at that laser etching at 2 W to the tooth surface for 15 seconds had statistically significant higher shear bond strength in comparison to conventional 37% phosphoric acid technique. The use of increasing the laser power output more than 2 W did not significantly increase the bond strength. The shear bond strength of all the three Laser etched groups was clinically acceptable. Enamel etching with Er: YAG Laser (2W for 15 seconds) produced maximum bond strength than acid etching and could be a viable alternative method.

Surface treatment of RMGIC to composite resin using different photosensitizers and lasers: A bond assessment of closed Sandwich restoration.

The aim of present study was to assess and compare different conditioning methods (laser, PDT and conventional) on shear bond strength (SBS) of resin modified glass ionomer cement (RMGIC) bonded to composite (sandwich technique). Fifty specimens were prepared from RMGIC and were packed in a teflon mould placed on glass slab. Through each of the glass slab the cement was light cured for 20 s. Now samples were randomly allocated into five groups (n = 10) according to pre-treatment protocols. In group 1 RMGIC were conditioned with MBP using PDT, Samples in group 2 treated with Er,Cr:YSGG (ECYL), group 3 pre-treated with Nd:YAG laser (NYL), samples in group 4 surface conditioned with air abrasion (AA) and group 5 conditioned with 37 % phosphoric acid (PA). Specimens after conditioning were rinsed with distilled water. Adhesive Adper Single Bond 2 was applied on treated surface of RMGIC and cured. Teflon mold was utilized to hold the composite Filtek Z250 in an incremental technique. For SBS testing all specimens were placed under shear knife edge at 1 K N at a speed of 0.5mm2 until bond failure. Optical microscope was used to evaluate failure pattern at 10x magnification. The data of SBS in Megapascal were subjected to statistical test. Analysis of variance was followed by Post hoc test with level of significance at 5 %. The maximum SBS was found in group 5 RMGIC conditioned with 37 % PA (16.45 ± 0.32 MPa). Whereas, group 1 (MBP, PDT) demonstrated significantly lower bond integrity (9.82 ± 1.08 MPa) compared to all experimental groups. Bond integrity of RMGIC surface treated with MBP, PDT (9.82 ± 1.08 MPa), group 3 lased with NYL (11.47 ± 0.53 MPa) and samples in group 4 conditioned with AA (11.23 ± 0.47 MPa) were comparable (p > 0.05). ECYL has a potential to be used for conditioning of RMGIC prior to composite restoration (sandwich technique). MBP at 100 mg/L deteriorates SBS of composite to RMGIC.

To Evaluate Shear Bond Strength of Resin Composite to Theracal Lc, Biodentine, and Resin–Modified Glass Ionomer Cement and Mode of Fracture: An In Vitro Study

Abstract Introduction The aim of the current study was to evaluate shear bond strength of resin composite bonded to Theracal LC, Biodentine, and resin-modified glass ionomer cement (RMGIC) using universal adhesive and mode of fracture. Materials and Methods A total of 50 caries-free maxillary and mandibular molars extracted were taken; occlusal cavities were prepared, mounted in acrylic blocks, and divided into five groups based on the liner used. Group 1: Biodentine liner placed into the cavity and bonding agent and resin composite applied after 12 minutes. Group 2: Biodentine liner placed into the cavity and bonding agent and resin composite applied after 14 days. Group 3: RMGIC liner placed into the cavity and bonding agent and resin composite applied immediately. Group 4: RMGIC liner placed into the cavity and bonding agent and resin composite applied after 7 days. Group 5: Theracal LC liner placed into the cavity and bonding agent and resin composite applied immediately. Each sample was bonded to resin composite using universal adhesive. Shear bond strength analysis was performed at a cross-head speed of 0.1 mm/min. Statistical Analysis Statistical analysis was performed with one-way analysis of variance and posthoc Bonferroni test using SPSS version 22.0. Results and Conclusion Biodentine liner when bonded immediately to resin composite showed minimum shear bond strength. RMGIC when bonded to resin composite after 7 days showed maximum shear bond strength. Mode of fracture was predominantly cohesive in groups having Biodentine and Theracal LC as liner.

Microstructure and strength of ultrasonic-assisted brazed joints of Si3N4/6061Al composites

The ultrasonic-assisted brazing of 30 vol.% Si3N4/6061Al composites in air using a filler metal comprising a Zn-Al alloy was investigated. Effects of the ultrasonic action duration and brazing temperature on the microstructure and mechanical properties of the brazed joints were focused on. The surface oxide layer between the composites and filler metals appeared to be broken and gradually removed by the ultrasonic action, and a composite bond with uniformly distribution of the reinforcements was formed eventually. As the ultrasonic action duration and brazing temperature increased, the proportion of Si3N4 particles and the atomic percentage of Al in the bond layer increased. Increasing the brazing temperature led to grain coarsening of the α-Al phase. The maximum shear bond strength of the joints was 183 MPa, and fracture occurred on the Al metal matrix composites side. The higher strength was attributed to the α-Al phase and Si3N4 particles being uniformly distributed in the bond layers.

Effects of 10-MDP Based Primer on Shear Bond Strength between Zirconia and New Experimental Resin Cement.

To date, numerous materials in the dental field are marketed to ensure stable adhesive cementation of zirconia ceramics (Y-TZP). The aims of this study were to assess the shear bond strength of the new experimental cement Surgi Dual Flo’ Zr to Y-TZP compared to Panavia V5 cement, and to evaluate the effect of 10-MDP (10-methacryloyloxydecyl dihydrogen phosphate) containing primer on their bond strength. Twenty composite cylinders and Y-TZP disks were adhesively luted and divided into four groups based on cement type used and application or not of 10-MDP. The groups (n = 5 each) were S 10MDP (Surgi Dual Flo’ Zr with 10-MDP); S no 10MDP (Surgi Dual Flo’ Zr without 10-MDP); P 10MDP (Panavia V5 with 10-MDP); P no 10MDP (Panavia V5 without 10-MDP). Maximum load resistance (ML) and shear bond strength (SBS) were tested and mode of failure qualitative documented via scanning electron microscopy. The data were analyzed with one-way ANOVA, Holm-Sidak method, and Bayesian analysis. ML and SBS were significantly higher in S 10MDP than in S no 10MDP; and in P 10MDP than in P no 10MDP (p < 0.05). No significant differences were found between S 10MDP and P 10MDP; S no 10MDP and P no 10MDP (p > 0.05). Cohesive, adhesive, and mixed failure occurred among the groups. Bond strength between the experimental resin-based cement and Y-TZP was adequate for clinical application when 10-MDP was added. 10-MDP containing primer was effective improving the bond strength to Y-TZP more than the different type of resinous cement.

High bonding strength between zirconia and composite resin based on combined surface treatment for dental restorations.

Zirconia is the preferred material for dental restorations; however, dental restorations are usually affected by zirconia fractures due to chipping and delamination of the veneer ceramic. One effective solution for repairing chemically inert zirconia frameworks is to strongly chemically bond them with the composite resin via surface modification. Thus, the bonding strength between the zirconia and composite resin determines the performance of dental restoration. Herein, we investigate the shear bond strength between zirconia ceramic and two ceramic repair systems before and after thermal cycling based on different surface pretreatments, including air-abrasion and a novel silane coupling agent. When treated with combined sandblasting, novel silane and 10-methacryloyloxydecyl hydrogen phosphate act as a bonding agent for the zirconia surface, and the maximum shear bond strength achieves 27.5 MPa, as measured by a universal testing machine through the average of 16 separate measurements. The results show that the combined treatment resists the interface damage caused by expansion and contraction during thermal cycling. The long-term bond durability is due to the micro-mechanical bond force formed by resin and ceramic, and the chemical bonds of Zr-O-Si at the interface. Results indicate that selective pretreating the surface results in high bond strength between the zirconia and the composite resin, which is meaningful to optimize dental restoration.

Influence of Expasyl and Viscostat on Bond Strength of Resin Composite to Dentin with Different Adhesives

The aim of the present study was to evaluate the influence of gingival retraction agents and different bonding regimes on the shear bond strength (SBS) of dentin to resin composite. Sixty human teeth were divided into six groups (n = 10) based different combinations of hemostatic agents (Viscostat and Expasyl) and dentin bonding regimes [Total-etch (TE) and self-etch (SE)]. Group A1, Expasyl and TE; group A2: Expasyl and SE; group B1: Viscostat and TE; group B2: Viscostat and SE, group C1 (control): No hemostatic agent and TE; group C2 (control): No hemostatic agent and SE. Composite build-ups (Tetric N Ceram) were performed after dentin treatments and SBS was assessed using universal testing machine. Failure analysis was performed with a stereomicroscope and classified as adhesive, cohesive and admixed. Data was analysed using ANOVA and multiple comparisons test. The maximum and minimum SBS was displayed by specimens in group C1 (36 59 ± 5 94 MPa) and group B2 (17 95 ± 2 52 MPa) respectively. Control groups (C1 and C2) showed statistically comparable SBS, which was significantly higher in comparison to experimental groups (A1, A2, B1, and B2) (p &lt; 0.05). Hemostatic agents inhibited the adhesive bond strength of composite to tooth dentin. Reversal effect of total-etch and self-etch bonding regimes on hemostatic agent treated dentin SBS was minimal.

Effect of acid etching, Er, Cr: YSGG laser conditioning and combining on shear bond strength of orthodontic metal bracket

The present study aims to evaluate the shear bond strength and the adhesive remnants index (ARI) of metal brackets. For this purpose, enamel etched with acid, Er; Cr: YSGG (2780 nm) laser, and a combination of them. In this study, 60 human premolars were divided into three groups (acid, Er, Cr: YSGG (2780 nm) laser, and combined etching). Each group contains 20 teeth. For testing of shear bond strength (SBS), the force applied by a universal testing machine. All the samples were examined under a light stereomicroscope to determine the bond failure mode. The results revealed that the laser-acid group had the maximum mean shear bond strength while the acid group had the minimum shear bond strength. The values of mean shear bond strength obtained of 25.90, 16.94, and16.60 MPa for laser-acid, laser, and acid, respectively. Laser and acid groups were negligibly different from each other, while they were significantly different from the lasers–acid group (p < 0.05). Regardless of the preparation of the enamel, bond failure occurred predominantly in the enamel-adhesive site. Er, Cr: YSGG (2780 nm) laser conditioning in combination with acid led to high shear bond strength, but the hazardous effect on tooth should be considered. The bond failure mode was almost similar among all three groups, where there was no adhesive left on the surface of the tooth.

Influence of Er,Cr:YSGG Laser Dentin Conditioning on the Bond Strength of Bioactive and Conventional Bulk-Fill Dental Restorative Material.

Objective: The aim of the study was to evaluate shear bond strength (SBS) and modes of failure for bioactive (BA) material when bonded to Er,Cr:YSGG lased dentin in comparison with other conditioning regimes. Materials and methods: One hundred twenty extracted teeth were mounted and allocated into eight groups (n = 15) according to the surface conditioning [group 1: Er,Cr:YSGG laser + BA; group 2: Er,Cr:YSGG laser + multi-core (MC); group 3: Er,Cr:YSGG + Ketac Conditioner (polyacrylic acid) + BA; group 4: Er,Cr:YSGG + Ketac Conditioner + MC; group 5: conventional etch and rinse + BA (Control); group 6: conventional etch and rinse + MC (Control); group 7: self-etch + BA; group 8: self-etch + MC]. Based on the type of bulk-fill material, samples from groups 1, 3, 5, and 7 were bonded to BA and groups 2, 4, 6, and 8 were bonded to conventional MC bulk-fill material. All specimens were tested for SBS using universal testing machine. Ten samples from each group were assessed for modes of failure. Data were assessed using analysis of variance and Tukey multiple comparisons test. Results: The maximum SBS value was in group 6 (18.96 ± 0.315) with etch and rinse dentin conditioning and bonded to MC. The minimum SBS value was exhibited by group 7 (16.04 ± 0.854) self-etch conditioning bonded to BA. SBS among group 6 specimens were significantly higher than that of specimens in group 7 (p < 0.05). Among all groups the most common type of observed failure was adhesive. Conclusions: Dentin surface treatment with Er,Cr:YSGG phototherapy for the adhesive bonding of BA and conventional bulk-fill resin composite MC showed comparable bond strength outcomes to conventional conditioning techniques. Er,Cr:YSGG laser dentin conditioning of dentin for bonding of bulk-fill BA materials has potential to be used clinically as it shows potential for adequate adhesive bond integrity.

In vitro comparison of shear bond strength of a flowable composite resin and a single-component glass-ionomer to three different pulp-capping agents.

Various materials are used for vital pulp capping and the bond strength of restorative materials to these pulp-capping agents significantly affects the success rate of vital pulp therapy. The aim of this study was to determine the shear bond strength of a flowable composite resin and a single-component glass-ionomer to mineral trioxide aggregate (MTA), calcium-enriched mixture (CEM) cement and BiodentineTM as pulp-capping agents. Seventy-two cylindrical acrylic resin blocks, with a central hole 4 mm × 2 mm, were prepared. Mineral trioxide aggregate, CEM cement and Biodentine were placed in the cavities (n = 24 in each group) and incubated for 24 h. The blocks were subdivided into the composite resin and glassionomer subgroups. Cylindrical plastic molds, measuring 3 mm in height and diameter, were used to place the restorative materials on the samples. The shear bond strength test was performed at a strain rate of 1 mm/min in a universal testing machine. The samples were evaluated under a stereomicroscope at ×25 magnification for fracture modes. The data was analyzed with the one-way analysis of variance (ANOVA) and Tukey tests. The maximum and minimum mean shear bond strength values were recorded in the Biodentinecomposite resin (4.77 MPa) and MTA-glass-ionomer (2.20 MPa) groups, respectively. There were significant differences in the mean shear bond strength values of MTA, CEM cement and Biodentine to the composite resin and glass-ionomer (p < 0.001). A composite material may be preferable for definitive filling after pulp capping with Biodentine.

Shear bond strength of orthodontic brackets bonded to a new all-ceramic crown composed of lithium silicate infused with zirconia: An in vitro comparative study

This study sought to determine whether a clinically acceptable shear bond strength (SBS) of metal orthodontic brackets is achievable to CAD/CAM (Computer-Aided Design/Manufacturing) lithium silicate infused with zirconia and whether a chemical pre-treatment bonding protocol produced a higher shear bond strength. Twenty lithium silicate infused with zirconia (CELTRA® DUO) samples, twenty zirconia samples, and twenty lithium disilicate samples were fabricated to replicate the facial surface of a mandibular left first molar. The samples were split into two test groups, one of which received a chemical pre-treatment protocol (hydrofluoric acid etch). Shear bond strength testing was conducted and the mean, maximum, minimal, and standard deviation SBS values for each were calculated and recorded in MPa. An Adhesive Resin Index (ARI) score was also assigned to each sample to assess the mode of bond failure. SBS of the lithium silicate infused with zirconia groups were significantly less than the chemically pre-treated lithium disilicate group, however both materials, when chemical pre-treatment protocol was used, were not statistically different than the enamel control. Orthodontic bonding to lithium silicate infused with zirconia yielded a weaker shear bond strength than bonding to traditional lithium disilicate, however, when the surface was pre-treated with hydrofluoric acid etch it provides a bond strength that is within an acceptable clinical range.

Comparison of Shear Bond Strength of Different Wire-Composite Combinations for Lingual Retention: An in Vitro Study

Context: As lingual bonded retainers are required for long-term retention in the oral cavity, the wire-composite combination of choice may be the determining factor for the success of lingual bonded retainers. Aim: We compared the shear bond strength of different wire-composite combinations used for lingual bonded retainers and identified the combination of choice for lingual retention in terms of the shear bond strength. Materials and Methods: A total of 108 extracted human maxillary premolars in pairs were divided into 6 groups of 9 samples each. Three different types of retainer wires (namely, Respond [Ormco Corp., Orange, CA, USA], Leone Ligature Wire [Leone S.p.a., Firenze, Italy], and SRW™ Stranded Retention Wire [Ortho Classic Inc., USA]) were bonded to the teeth with the composites (G-aenial™ Universal Flo and Tetric N-Flow). The shear bond strength was measured on debonding using universal testing machine INSTRON. Results: The maximum shear bond strength (58.28 N) was observed in group IV (Respond wire with Tetric N-Flow), whereas the minimum (25.28 N) was observed in group VI (SRW™ Stranded Retention Wire with Tetric N-Flow). A highly significant difference was observed when the shear bond strength of group IV was compared with all the other groups. Conclusions: The maximum shear bond strength was observed in the wire-composite combination of Respond dead-soft wire with Tetric N-Flow composite. Therefore, it could be the wire-composite combination of choice for bonded lingual retainer.

Effects of different dentinal drying methods on the adhesion of glass ionomer restorations to primary teeth.

Glass ionomer cements that form an inevitable part of pediatric restorative dentistry are inherently sensitive to moisture. The influence of different drying techniques on the shear bond strength of glass ionomer cements to primary teeth dentin has not been established. The purpose of the study was to evaluate the effects of different drying methods for different drying time periods on the shear bond strength of GC Fuji IX to primary tooth dentine. A total of 135 caries-free primary teeth were selected and ground to a flat dentinal surface. Specimens were randomly divided into three groups - air dry, blot dry, and suction dry of 45 specimens each. Of these, 15 specimens each were dried for 2 s, 5 s, and 10 s. GC Fuji IX was condensed into Teflon molds, and the specimens were subjected to shear bond strength testing. The mean shear bond strength values for the different time intervals were analyzed with analysis of variance test. In the air-dry group, the maximum shear bond strength values were obtained when the specimens were dried for 5 s and the least when dried for 2 s (P = 0.00). In the blot-dry and suction-dry groups, the highest values were obtained when the specimens were dried for 10 s and least for 2 s (P = 0.039 and 0.000, respectively). Among the three drying methods employed in the study, the maximum shear bond strength of the glass ionomer restoration was observed in the air-dry group.

Evaluation of Different Pretreatment Efficacy with Fluoride-releasing Material on Shear Bond Strength of Orthodontic Bracket: An In Vitro Study

The aim of this study was to assess the efficacy of different pretreatments with fluoride-releasing material on shear bond strength (SBS) of orthodontic bracket. A total of 60 human mandibular premolars were taken in this study. These samples were stored in periodically changed distilled water at room temperature so as to stop bacterial growth. All samples were randomized to three pretreatment groups: group I, acid etching; group II, fluoride varnish; group III, casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) paste. Later, Transbond XT was applied on brackets made of stainless steel and brackets were centered buccally and then light-cured. The INSTRON universal machine was used to measure SBS. Based on the values, the adhesive remnant index (ARI) was estimated. The maximum SBS was seen in group III (18.84 μ 1.04), followed by group II (14.18 μ 0.23), and the minimum bond strength was found in group I (13.90 μ 1.22). The one-way analysis of variance (ANOVA) showed high statistically significant difference within the pretreatment groups. The pretreatment group comparisons showed statistically significant difference between group I vs group III and group II vs group III. Score 0 was more in group III [8 (40%)] followed by group II [4 (20%)] and group I [2 (10%)]. The lowest number of score 3 was found in CPP-ACP paste group. After comparing the ARI scores within the groups, the Chi-square test showed a probability of 0.001 which was statistically significant. Our study established that the CPP-ACP paste pretreatment improves the SBS of orthodontic bracket significantly followed by fluoride varnish and acid etching. The bond strength of orthodontic brackets that were bonded should be adequate to resist orthodontic forces applied during treatment. The effect of the adhesive material to improve the adequate bond strength depends on the efficient pretreatment methods.

A comparative evaluation of the effect of liners on the shear bond strength of veneered zirconia block: An in vitro study.

Aim:This study aims to evaluate the effect of lithium disilicate glass–ceramic liner, silicon dioxide based liner, and glass–ceramic interlayer on the shear bond strength (SBS) of a commercially available veneered zirconia block and to study fractographic behavior of the samples using universal testing machine, scanning electron microscope (SEM).Setting and Design:In vivo – comparative study.Materials and Methods:60 samples were fabricated from VITA (vita zahnfabrik. Bad sackingen, Germany) zirconia discs. Samples were divided into 4 groups with 15 samples each. First is the control group, second is lithium disilicate glass–ceramic liner group, third is silicon dioxide based liner, and fourth is glass–ceramic interlayer group. SBS of samples was recorded using universal testing machine. Samples were further analyzed for fractographic behavior using SEM.Statistical Analysis Used:One Way ANOVA test, and Chi-Square test.Results:The intergroup comparison of mean SBS (Mpa) was done using the post hoc Bonferroni test. The mean SBS (Mpa) was significantly more among lithium disilicate and glass–ceramic interlayer groups in comparison to silicon dioxide-based liner group. Fractographic analysis was done using the Chi-square test.Conclusion:It was concluded that maximum SBS was obtained for lithium disilicate liner. Maximum adhesive failures were found with lithium disilicate liner, and silicon dioxide-based liner group showed cohesive failures.

Composite nanostructured hydroxyapatite/yttrium stabilized zirconia dental inserts – The processing and application as dentin substitutes

The objective of the study was to process nano-structured hydroxyapatite/yttrium-stabilized zirconia bioceramic and to investigate the possibilities of its application as dentin replacement in the form of dental inserts. The processing conditions were varied in order to optimize phase composition, microstructure, fracture toughness, hardness and shear bond strength (SBS) between the obtained composite inserts and restorative materials, following either the "total-etch" or „self-etch“ clinical protocol. Composite nano-powder, obtained by mixing and homogenization of 80 wt% of stoichiometric hydroxyapatite (HAp) synthesized by modified precipitation method and 20 wt% of yttrium-stabilized ZrO2 (YSZ) synthesized by plasma method, was isostatically pressed into cylinder-shaped green bodies. After dilatometric analysis, HAp/YSZ inserts were sintered in the temperature range from 1200 °C to 1300 °C. Hardness and fracture toughness of sintered inserts were ranged between 3.90 ± 0.20 – 3.95 ± 0.12 GPa and 1.82 ± 0.04 – 1.88 ± 0.03 MPam1/2, respectively. Microstructural analysis of biphasic HAp/t-ZrO2 inserts indicated two potential fracture mechanisms for fracture toughness increasing. Sintering temperature and different clinical protocols affected SBS between processed inserts and commercial dental restorative materials. Maximum SBS values of 10.50 ± 4.94 MPa (mean±standard deviation) were reached in inserts sintered at 1300 °C, following the „self-etch“ protocol of adhesive application. It could be concluded that resin-based composites could be strongly bonded to HAp/YSZ inserts, preferably with „self-etch“ adhesive application. In addition, the values of fracture toughness and hardness of the obtained inserts indicated the possibility of their usage as dentin substitutes, which could be a good prerequisite for satisfactory mechanics of restored teeth.

Joining of aluminum alloy and polymer via friction stir lap welding

Sound hybrid joint was achieved with a sufficient mixture of 6061-T6 aluminum (Al) alloy and polyether ether ketone (PEEK) via friction stir lap welding (FSLW) by a tapered thread pin with the triple facets. The larger length ratio between the Al anchor and the rotating pin reached approximately 0.8 at low welding speeds due to the dynamic flow induced by the triple facets. The mechanical interlocking and adhesive bonding attributed to the high-quality joining. Increasing welding speed resulted in the reduction of the adhesion area and the decrease in the size of the Al anchor, deteriorating the mechanical interlocking. A high-quality with the maximum shear bond strength of 20 MPa was achieved through the big Al anchor with a high hardness value. The tapered thread pin with the triple facets has feasible and potential to FSLW of metal and polymer in terms of enhancing mechanical interlocking.

Effect of Erbium-yttrium, scandium, gallium and garnet (Er-YSGG) laser on the bond strength of lithium disilicate ceramics.

Objectives:To assess the bond strength of LD ceramics with resin composite material and surface conditioning using Er: YSGG laser and HF acid.Methods:Thirty LD ceramic (Emax, Ivoclar vivadent) discs were prepared using hot pressing technique and treated with hydroflouric acid (Group-1-HF acid) (9%) (n=10) and Er- yttrium, scandium, gallium and garnet laser (Group-2-ER-YSGG laser) (Waterlase iPlus, 10 Hz and power of 0.5 W, pulse duration of 230 μs) (n=10). Ten specimens were left untreated to be included as controls (Group-3-Control). All the specimens were treated with Adper Single Bond adhesive (3MESPE, St. Paul, MN, USA). Multicore buildups (3mmx3mm) were performed using a rubber mold on the ceramic surfaces and cured using LED light-curing unit for 140 sec. All specimens were tested using shear bond test and failure modes were assessed with a stereomicroscope and scanning electron microscope. Data was analysed using ANOVA and Tukey Kramer multiple comparisons test.Results:The maximum and minimum shear bond strength values were achieved in HF Acid specimens (Group-1) (28.15±4.72 MPa) and control specimens (13.47± 3.14 MPa) respectively. Specimens treated with HF acid showed significantly higher bond strength in comparison to laser treated and control specimens (p<0.01). Laser treated specimens had significantly higher bond strength as compared to controls (p<0.01).Conclusions:Hydrofluoric (HF) acid treatment showed significantly better outcomes than YSGG laser surface treatment.

The addition of carbon nanotubes to orthodontic adhesives: an in vitro study

Abstract Objective The evolution of adhesive dentistry and the addition of nanoparticles has heralded an improvement in the mechanical properties of adhesives. Thus, the aim of the present study was to evaluate the effects produced by carbon nanotubes (CN) added to two adhesives used for indirect bonding by an examination of the shear bond strength (SBS) and location of bond failure. Methods One hundred and sixty bovine incisors were randomly divided into eight groups (N = 20): (1) indirect bonding with Sondhi adhesive; (2), (3) and (4) indirect bonding with Sondhi adhesive into which CN at 0.5%, 0.25% and 0.05% concentrations were incorporated; (5) indirect bonding with Concise adhesive; (6), (7) and (8) indirect bonding with Concise adhesive into which CN at 0.5%, 0.25% and 0.05% concentrations were incorporated. Following etching with 37% phosphoric acid and the placement of brackets, maximum shear bond strength (SBS) was measured with a mechanical testing machine. The location of bond failure was evaluated using the Adhesive Remnant Index (ARI). The SBS between groups and ARI scores were statistically analysed (p &lt; 0.05). Results There was no statistical difference (p &gt; 0.05) in SBS or ARI. Conclusions CN addition to Concise and Sondhi adhesives did not influence the SBS and the ARI of the brackets. Therefore, in the conditions of this experiment, there was no benefit in the addition of CN to orthodontic adhesives.

Effects of at-home and in-office bleaching agents on the shear bond strength of metal, ceramic, and composite brackets to enamel.

This study aimed to evaluate the effects of at-home and in-office bleaching on the shear bond strength (SBS) of metal, ceramic, and composite orthodontic brackets and to compare their SBSs. A total of 96 human lower premolar teeth were used for this study. Six teeth were used for scanning electron microscopic study while the remaining ninety were divided into three equal groups. Each group was further subdivided into three subgroups with ten samples each. Three protocols were used. In the at-home bleaching group (n = 30), opalescence non-PF (potassium nitrate and fluoride) bleaching agent (10% carbamide peroxide) was applied onto the teeth daily for 14 days and left for 8 h each day. Teeth in the in-office group (n = 30) were treated twice in consecutive days with Opalescence boost PF (40% hydrogen peroxide). After bleaching, the specimens were stored in distilled water for 1 day before bonding. SBS testing was performed on all teeth using Instron universal testing machine. Analysis of variance indicated a significant difference (P < 0.005) among the groups. Maximum SBS was shown by ceramic brackets in control group (Ib) and minimum was shown by composite brackets of in-office bleached group (IIIc). The results showed that at-home bleaching did not affect the SBS significantly whereas in-office bleaching reduced SBS of metal, ceramic, and composite brackets significantly. It is preferable to use metal or ceramic brackets than composite brackets for bonding 24 h after bleaching.