Differences In Shear Bond Strength Research Articles

Effect of Ti: Sapphire and Nd: YAG Lasers on Shear Bond Strength at the Zirconia - Veneering Ceramic Juncture.

Introduction: This study was conducted to assess the impact of nanosecond and femtosecond lasers on shear bond strength at the zirconia - veneering ceramic juncture. Materials and Methods: The first 60 samples of partially sintered zirconia cylindrical discs measuring 7 mm diameter and 4 mm height were milled and sintered. Then they were randomly divided into three groups namely group C (control, n=10), group N (Nd: YAG laser, n=10), and group T (Ti: sapphire laser n=40) which was further divided based on the duration of laser irradiation, into 4 subgroups (n=10 each) which were 30 seconds, 1 minute, 2 minutes and 3 minutes. Surface treatment was done on sintered zirconia discs based on the group. Following the treatment, the discs were ultrasonically cleaned followed by liner application (IPS Emax Zirliner, Ivoclar-Vivadent) and veneer ceramic layering (IPS e.max Ceram, Ivoclar-Vivadent) of 1.5 mm height. Each sample underwent shear stress in the universal test machine on the mounting jig, and bond strength was evaluated. Data were assessed using ANOVA followed by Tukey's post hoc multiple comparison analyses. Results: According to one-way ANOVA, there was a significant difference in shear bond strength between the groups. Tukey's post hoc pair wise comparison test showed a significant difference (P value = 0.001) in shear bond strength of all pairs except group C and group N. The results of repeated measures, ANOVA (related and dependent groups) and Tukey's multiple pair wise comparison test showed that there was a significant difference (P value = 0.001) in shear bond strength at 30 seconds and all other groups. Conclusion: Ti: sapphire laser irradiation for 30 seconds can be used as potential surface treatment to increase shear bond strength at the zirconia-veneering ceramic juncture.

Bond strength of orthodontic buttons on clear aligner materials

ABSTRACT Purpose To evaluate the shear bond strength of orthodontic buttons bonded on various clear aligner materials using orthodontic plastic adhesive. Materials and methods Three types of thermoplastic materials: 1) Duran (Polyethylene terephthalate glycol), 2) Essix A+ (Polyethylene terephthalate glycol), and 3) Zendura (Polyurethane) were bonded with either metal or plastic buttons using orthodontic plastic adhesive (Bond aligner®). Six experimental groups with 15 specimens per group were prepared. Bond strength testing was done according to the Lap Shear Test Method (ASTM D3163) using the universal testing machine. Bond failure mode (modified from ASTM D5573) was examined with a stereoscope. Kruskal-Wallis and post hoc tests were used to analyse the differences in shear bond strength among the six groups. Results Mean bond strengths were as follows: 1) Duran-metal (DM) (7.04 MPa); 2) Duran-plastic (DP) (5.37 MPa); 3) Essix-metal (EM) (5.55 MPa); 4) Essix-plastic (EP) (4.62 MPa); 5) Zendura-metal (ZM) (1.17 MPa); and 6) Zendura-plastic (ZP) (1.40 MPa). Shear bond strength among the three thermoplastic materials were significantly different (p < .05). For the bond failure mode, regardless of button type, Duran and Essix A+ showed substrate failure of the thermoplastic sheet, while Zendura showed adhesive failure at the thermoplastic sheet interface. Conclusion Orthodontic buttons bonded on Duran and Essix A+ using orthodontic plastic adhesive could achieve very high bond strength that the thermoplastic sheets would tear before button detachment occurred. Buttons bonded to Zendura resulted in significantly greater bond failure rates.

The Effect of Curing Pressure on Shear Bond Strength of Zirconia to Resin Cement

Background: Nowadays, the esthetics demand is continuously increasing; therefore, metal-free materials are widely used, like a zirconia-based ceramic, which is conveniently fabricated via computer-aided design and computer-aided manufacturing (CAD/CAM) system for restorations from single to full mouth rehabilitation. Objective: This study evaluated the effect of pre-curing pressure on the shear bond strength of zirconia to the resin cement. Methods: A total of sixty-three sandblasted cylindrical zirconia mounted in autopolymerizing resin were randomly assigned to three groups; Group 1: no treatment (control), Group 2: negative pressure, and Group 3: positive pressure to resin cement after resin cement application and resin composite columns bonded to zirconia. Thirty-three of the samples were stored in distilled water at 37 °C for 24 hr before the shear bond strength test for thirty samples and three samples were cross-sectionally cut for interfacial observation with FESEM. Another thirty samples were thermocycled for 5,000 cycles in distilled water at 5°C to 55 °C before testing. The shear bond strength and failure mode were evaluated. Examination of the bonding interface was also done. Results: The results were analyzed using two-way ANOVA. The means of shear bond strength of non-thermocycle of the control group were 8.01 ±1.74 MPa, 9.10 ±1.90 MPa, and 9.14 ±2.58 MPa, whereas that of thermocycle group were 5.71 ±0.84 MPa, 5.53 ±0.68 MPa, and 5.68 ±0.77 MPa in zero pressure group, negative pressure group, and positive pressure group, respectively. It showed no statistically significant differences in shear bond strength in all pressure groups (p &gt; 0.05). The pre-curing pressure did not influence the shear bond strength of the zirconia and resin cement. Conclusion: There was no difference in the shear bond strength between the pressure groups and the no treatment control group. The positive and negative pressure did not influence the shear bond strength of the zirconia and resin cement.

Effect of Contamination with Hemostatic Agent on Shear Bond Strength of Composite to Dentin Using G-Premio and Single Bond Universal Adhesives.

Objectives: Bond strength of composite restorations plays an important role in their success. This in vitro study evaluated the effect of a hemostatic agent on shear bond strength of universal adhesives. Materials and Methods: Thirty-six extracted human molars were used in this study. Buccal and lingual surfaces were reduced to obtain flat dentin surfaces and were ground with a silicone paper. The samples were randomly divided into three groups (n=12) based on the application of hemostatic agent: group 1: no contamination (control), group 2: aluminum chloride application, and group 3: ferric sulfate application. Each group was then divided into two subgroups (n=6) for using G-Premio and Single Bond Universal. Resin cylinders (Filtek Z550) were bonded to dentin surfaces according to the manufacturer’s instructions. After 1000 thermal cycles, shear load was applied to the specimens using a universal testing machine at a crosshead speed of 1 mm/min until failure. Data were statistically analyzed using two-way ANOVA and Tukey’s post-hoc test (α=0.05). Results: There were statistically significant differences in shear bond strength of the three main groups for both G-Premio and Single Bond Universal (P<0.05). When the adhesive systems were compared with each other, G-Premio showed higher shear bond strength than Single Bond Universal (P<0.05). Conclusion: Contamination with hemostatic agents had an adverse effect on the shear bond strength of universal adhesives. Moreover, G-Premio yielded a higher bond strength than Single Bond Universal.

Use of two kinds of antioxidants to restore the bond strength of bleached enamel.

This work aimed to evaluate the ability of two kinds of antioxidants, namely, grape-seed extract and sodium ascorbate, in restoring bond strength at the resin-enamel interface after bleaching. Ten groups of samples with 15 teeth per group were prepared for shear-bond-strength test at the resin-enamel interface after bleaching. The groups were as follows: control; no antioxidant; 2.5%, 5%, 10%, or 15% grape-seed extract; and 2.5%, 5%, 10%, or 15% sodium ascorbate. The peak values of shear bond strength when resin was debonded from teeth and the failure modes under a microscope were recorded. Ten other groups of teeth with two teeth per group were prepared and treated in a similar approach before resin bonding. The samples were cut vertically to the bonding interface. The structures of the bonding interface were compared by scanning electron microscopy. No statistically significant difference in shear bond strength was found among the no-antioxidant, 2.5% grape-seed extract, and 2.5%, 5%, or 10% sodium ascorbate groups (P>0.05), which were statistically significantly lower than the control group (P<0.05). Evidence of marginal gap was observed at the resin-enamel interface, and resin tags in enamel were short, poorly defined, and fragmented. No statistically significant difference in shear bond strength was found among 5%, 10%, or 15% grape-seed extract, 15% sodium ascorbate, and control groups (P>0.05). No evidence of discontinuity was found at the adhesion interface, and resin tags in enamel were long, well defined, and structurally intact. Failure in the adhesive joint was the major debond mode in all experimental groups. Immediately after bleaching, the bond strength of dental enamel significantly decreased. Bond strength can be restored by 5% grape-seed extract or 15% sodium ascorbate in 5 min.

EFFECT OF ETCHING TECHNIQUES ON THE SHEAR BOND STRENGTH OF ADHESIVE PRECOATED BRACKETS BONDED IN VITRO

This study was designed to compare shear bond strength durability of two etching techniques namely conventional etching and self-etching primer techniques, when using Adhesive pre-coated brackets (APCII). Thirty extracted premolars were divided into two equal groups (group 1: etched with 37% Phosphoric acid and group 2: bonded with transbond plus self-etching primer), each group was further subdivided into three subgroups each of them contains five teeth, at different storage times: 24 hours, 30 days and 3 months. Universal testing machine was used to measure shear bond strength. T-test revealed that there was no significant difference in shear bond strength between the two etching techniques at 24 hours and 30 days, while showed a highly significant difference (P ≤ 0.01) at 3 months. For the three storage times, self-etching primer showed less adhesive remnant on the teeth than that of Phosphoric acid etching. It can be concluded that self-etching primer provided shear bond strength Comparable to that of phosphoric acid, and it has less adhesive remnant than conventional etching technique.

Effect of over-the-counter whitening strips and toothpaste on shear bond strength of orthodontic brackets.

BackgroundTo investigate: 1) the effects of over-the-counter white strip enamel bleaching and 2-Step whitening toothpaste application on the shear bond strength of orthodontic brackets at 24-hours and 7-days post-bleaching latent period; and 2) the correlation between amount of bleaching and shear bond strength. Material and MethodsSixty human premolar teeth were randomly assigned into two bleaching groups, white strip group treated with Crest® 3D WHITE™ LUXE Professional Effects Whitestrips (Proctor & Gamble, Greensboro, NC), and whitening toothpaste group, treated with Crest® 3D WHITE™ BRILLIANCE 2-Step Toothpaste (Proctor & Gamble, Greensboro, NC). The groups were further divided into 4 subgroups A, B, C, D (n=15 per group). Subgroups A and C were bonded 7 days after bleaching while subgoups B and D were bonded 24 hours after bleaching. Differences in shear bond strength between the subgroups and an unbleached control group (n=15) were compared using the Kruskal-Wallis test. Spectrophotometric color changes were recorded pre- and post-bleaching. ResultsThe mean shear bond strength for the white strip groups were 10.35±3.6 MPa and 11.69±4.33 MPa for the 7-day and 24-hour delayed bonding periods, respectively. Means for the whitening toothpaste groups were 11.01±4.31 MPa and 10.83±3.79 MPa for the 7-day and 24-hour delayed bonding periods. The mean for the control group was 9.59±3.32 MPa. There were no significant differences in shear bond strength between the groups at 7-days and 24-hour (P=0.650). There was a significant difference between teeth bleached with white strips as compared to those bleached with toothpaste and controls. The correlations between color change and shear bond strength were not significant (P=0.448). ConclusionsThere is a significant difference in the amount of whitening achieved by over-the-counter white strips compared to toothpaste; however, no significant effects on shear bond strength occurred after bleaching with white strips and toothpaste at 24-hours and 7-days. Key words:Bleaching, shear bond strength, orthodontics, over-the-counter.

Reversal of deleterious effect of extracoronal in- office bleaching on shear bond strength of composite resin to bleached enamel: Effect of delayed restoration and different antioxidants application - in vitro study

Objective:The objective of this in - vitro study was to evaluate the effect of different antioxidants in reversal of of deleterious effect of bleaching on shear bond strength of composite resin to bleached enamel.Materials and methods: Seventy bovine incisors were used. The specimens were randomly divided into seven groups (10 specimens each) as follow: Group 1: no bleaching treatment and no antioxidant application. Group 2: bleaching only without antioxidant application and immediate composite resin application after bleaching. Group 3: bleaching only without antioxidant application and delayed composite application (after 2 weeks) of storage. Group 4: bleaching and application of 10% Alpha-tocopherol.Group 5: bleaching and application of 6% cranberry extract. Group 6:bleaching and application of 10% sodium ascorbate. Group 7: bleaching and application of 10% green tea. 40% hydrogen peroxide (Opalescence Xtra Boost 40%, Ultradent, South Jourdan, UT, USA) was used. Composite resin Tetric N -Ceram was used. The shear bond strength was measured using a universal testing machine. Results: one-way ANOVA test revealed significant differences in shear bond strength among the tested groups (p < 0.001). Bond strength significantly decreased after bleaching. There was no significant difference in shear bond strength reversed using10% Alpha-tocopherol, 10% sodium ascorbate and 10% green tea and delayed restoration. Whereas the difference was significant between group 5(6% cranberry extract) and other antioxidants groups. Conclusion: The results obtained from the use of antioxidants using (10% Alpha-tocopherol, 10% sodium ascorbate and 10% green tea extract) is approximately the same as the delayed restoration.

Performance of Different Orthodontic Brackets after Exposure to Dietary Components: An &amp;lt;i&amp;gt;in Vitro&amp;lt;/i&amp;gt; Pilot Study

Introduction: The aim of this study was to determine whether there was a significant difference in shear bond strength between metal and ceramic brackets when exposed to acidic dietary components (beverages) and to observe the chromogenic potential of each in vitro. Methods: Metal and clear orthodontic brackets were placed on extracted maxillary second premolars and exposed to select beverages three times daily for four weeks. Shade was taken using a colorimeter device at seven intervals and the shear bond strength of each bracket was recorded. Results: There was a variable change in tooth shade with respect to the various beverages in which they were submerged. Coffee and Dr. Pepper had the most pronounced change, whereas Red Bull and water produced little to none, respectively. Compared to controls, brackets submerged in coffee had the greatest reduction in shear bond strength, followed by Dr. Pepper, then Red Bull. Overall, clear brackets showed higher shear bond strength than metal brackets. Conclusion: Acidic dietary components have a negative effect on the shear bond strength of orthodontic brackets, and more pigmented beverages have a higher chromogenic staining potential.

A comparative evaluation of shear bond strength between self-cured resilient liner and denture base resin with different surface treatments

Statement of problem: Soft denture liners are widespread materials used in prosthetic dentistry. Their mechanical properties have to meet several key requirements such as adequate bond to denture base resins in order to provide right function of masticatory system and oral hygiene. Purpose: To evaluate and compare the shear bond strength between a commercially available self-cured silicon-based liner and polymethyl methacrylate (PMMA) denture base resin with different surface treatments. Materials and Methods: A soft denture liner Ufi-Gel P (silicone-based liner) and polymethyl methacrylate denture base resin (Rodex) were chosen for this study. A total of 50 samples were made, the samples were divided into five groups, containing 10 samples each. Group I: Consisted of an untreated surface of polymethyl methacrylate which acted as the control. Group II: The polymethyl methacrylate surface was treated with Acetone. Group III: The surface of polymethyl methacrylate surface was treated with laser Er:YAG with three different pulses duration. The shear bond strength was examined by Instron Universal Testing Machine at crosshead speed of 40mm/min. T-student test was used to analyze the data (α=0.05). Results: There was a statistically significantly difference in shear bond strength between laser-treated and untreated specimens (P

Evaluation of Surface Preparations Combined With Different Generations of Bonding on the Bond Strength of Resin Composite Repair: An Original Article

Background: This study evaluated the effect of different mechanical surface preparation methods, as well as different adhesives including universal bonding agents, on the shear bond strength of composite repairs. Methods: This study was experimentally performed on 64 Z250 composite discs (3M, ESPE) with 6 mm diameter and 2 mm height. A total of 60 samples were randomly divided into 6 groups as follows: Group A) diamond milling + Adper Single Bond 2, group B) diamond milling + Single Bond Universal, group C) diamond milling + All Bond Universal, group D) sandblast + Adper Single Bond 2, group E) sandblast + Single Bond Universal, group F) sandblast + All Bond Universal. Then, the new composite was placed on the bonding layer, cured, and underwent aging again. The samples were assessed for shear bond strength by universal testing machine and their failure mode was investigated under the light microscope (20x and 100x). Finally, 4 remaining samples, which were surface-prepared by diamond milling and sandblasting, were evaluated for qualitative analysis of surface roughness using scanning electron microscopy (SEM) and atomic force microscopy (AFM). Data were analyzed by oneway ANOVA and Fisher’s exact tests. Results: There was no statistically significant difference in shear bond strength and failure mode among the groups (P> 0.05). However, diamond milling + Single Bond Universal group showed the highest and Adper Single Bond 2 had the lowest bond strength. Conclusions: There was no significant difference in bond strength using different methods. Therefore, diamond milling + Single Bond Universal was suggested as the best and most available method compared to sandblasting.

Effect of Ceramic Surface Treatment and Adhesive Systems on Bond Strength of Metallic Brackets.

Objective This study evaluated the effect of ceramic surface treatments on bond strength of metal brackets to machinable ceramics and veneering porcelain using different adhesive resins. Materials and methods. Machined ceramic specimens (10 × 10 × 2 mm) were prepared from Vitablocs mark II (Vita) and IPS e.max® CAD (Ivoclar). Layered porcelain fused to metal (IPS d.Sign®, Ivoclar) was used to fabricate PFM specimens (n = 60/group). Half of specimens were etched (9.6% HF, 15 sec), and the rest were nonetched. Three resin bonding systems were used for attaching metal brackets (Victory series™ APC II, 3M) to each group (n = 10): Transbond™ XT (3M), Light Bond™ (Reliance), or Blugloo™ (Ormco), all cured with LED curing unit (Bluephase G1600, Vivadent) for 50 s each. Specimens were immersed in deionized water at 37°C for 24 hours prior to shear bond testing (Instron) at crosshead speed of 0.5 mm/min. Debond surface of ceramic and bracket base was examined for failure mode (FM), Ceramic Damage Index (CDI), and Adhesive Remnant Index (ARI). ANOVA and post hoc multiple comparisons were used to analyze the differences in bond strength. The chi-squared test was used to determine significance effect of FM, CDI, and ARI. Results Significant differences in shear bond strength among group were found (p ≤ 0.05) related to ceramic, surface treatment, and resin cement. Conclusion Bond strength of bracket to ceramic is affected by type of ceramic, resin cement, and ceramic surface conditioning. Etching ceramic surface enhanced ceramic-bracket bond strength. However, bond strengths in nontreated ceramic surface groups were still higher than bond strength required for bonding in orthodontic treatment.

Influence of Different Surface Treatments on the Shear Bond Strength of Resin Cement to Base Metal Alloys.

Introduction: This study aimed to investigate the effect of different surface treatments on the bond strength of resin cement to nickel-chrome (Ni-Cr) alloy. Methods: Forty disk-shaped specimens of Ni-Cr alloy were prepared and divided into 4 groups. In the first group, the specimens' surface was sandblasted with 50 µ Al2 O3 particles. In the second group, the specimens were prepared with the Er:YAG laser. In the third group, the specimens were prepared using the Er:YAG laser after sandblasting. In the fourth group, the specimens' surface was covered with a thin layer of MKZ metal primer after sandblasting. Then the cylinders of composite resin were bonded to the treated metal surfaces using Panavia F2.0 resin cement. All of the samples were subjected to 2000 thermal cycles. The shear bond strength was tested using a universal testing machine at the crosshead speed of 0.5 mm/min. The failure mode was also observed by a stereomicroscope. Data were analyzed using the one-way ANOVA and the Tukey HSD test at a significance level of 0.05. Results: The shear bond strength from the highest to the lowest were as follows: the Er:YAG laser group, the sandblast and MKZ primer combination group, the sandblast group, and the sandblast and Er:YAG laser combination group. The mean differences of shear bond strength between the Er:YAG laser group and the sandblast group (P=0.047) and also between the Er:YAG laser group and the sandblast and Er:YAG laser combination group (P=0.015) were statistically significant. Conclusion: Among the different surface treatments employed in this study, Er:YAG laser treatment increased the shear bond strength between the metal alloy and the resin cement (Pavnavia F2).

Influence of Er:YAG Laser on the Shear Bond Strength of Resin Cement to Base Metal Alloy

Introduction: This study aimed to investigate the effect of different surface treatments on the bond strength of resin cement to nickel-chrome (Ni-Cr) alloy. Methods: Forty disk-shaped specimens of Ni-Cr alloy were prepared and divided into 4 groups. In the first group, the specimens’ surface was sandblasted with 50 μ Al2O3 particles. In the second group, the specimens were prepared with the Er:YAG laser. In the third group, the specimens were prepared using the Er:YAG laser after sandblasting. In the fourth group, the specimens’ surface was covered with a thin layer of MKZ metal primer after sandblasting. Then the cylinders of composite resin were bonded to the treated metal surfaces using Panavia F2.0 resin cement. All of the samples were subjected to 2000 thermal cycles. The shear bond strength was tested using a universal testing machine at the crosshead speed of 0.5 mm/min. The failure mode was also observed by a stereomicroscope. Data were analyzed using the one-way ANOVA and the Tukey HSD test at a significance level of 0.05. Results: The shear bond strength from the highest to the lowest were as follows: the Er:YAG laser group, the sandblast and MKZ primer combination group, the sandblast group, and the sandblast and Er:YAG laser combination group. The mean differences of shear bond strength between the Er:YAG laser group and the sandblast group (P = 0.047) and also between the Er:YAG laser group and the sandblast and Er:YAG laser combination group (P = 0.015) were statistically significant. Conclusion: Among the different surface treatments employed in this study, Er:YAG laser treatment increased the shear bond strength between the metal alloy and the resin cement (Pavnavia F2).

Comparison of the Bond Strength of Composite Resin to Zirconia and Composite Resin to Polyether Ether Ketone: An In Vitro Study.

ABSTRACTAim:The aim of the study was to compare the shear bond strength of composite resin bonded to polyether ether ketone (PEEK) and zirconia, and also to evaluate the effect of thermocycling on the shear bond strength.Materials and Methods:A total of 22 zirconia (Group 1) and 22 PEEK (Group 2) specimens (disks of 10 mm in diameter and 10 mm in thickness) were machine milled using computer-aided design (CAD)/computer-aided manufacturing (CAM) from commercially available zirconia and PEEK. These specimens were air abraded with 110-μm aluminum oxide. Following which these two groups were subdivided into four groups, that is, Group 1A: 11 zirconia specimens before thermocycling, Group 1B: 11 zirconia specimens after thermocycling, Group 2A: 11 PEEK specimens before thermocycling, and Group 2B: 11 PEEK specimens after thermocycling. These four groups of specimens were embedded in an acrylic block, and bonding agent was applied over the upper surfaces of the disks of each of these specimens. Composite resin was then cured, and then Group 1B and group 2B were thermocycled under a standard temperature. The bond strength of the specimen was tested using universal testing machine.Result:The result showed that there was no significant difference in shear bond strength between the groups, although higher shear bond strength was observed in the PEEK group.Conclusion:Shear bond strength of PEEK is similar to zirconia. The results suggest that the pretreatment method and primers used were effective in improving the bonding of resin cements to zirconia ceramic and the bonding properties of the veneering resin to the PEEK surface.

Assessing the Effects of Air Abrasion with Aluminum Oxide or Glass Beads to Zirconia on the Bond Strength of Cement

The purpose of this study was to evaluate the effects of air abrasion with aluminum oxide or glass beads to three types of zirconia containing various levels of cubic crystalline phases (3Y-TZP, Katana ML; 4Y-PSZ, Katana STML; and 5Y-PSZ, Katana UTML, Noritake) on the shear bond strength of resin cement. Thirty block specimens (8 × 8 × 3.5 mm) were milled out of each zirconia material and mounted in plastic pipe. Ten specimens of each of the zirconia materials were air-abraded using 50 μm aluminum oxide particles, ten specimens were abraded using 80 μm glass beads, and ten specimens served as a control and received no surface treatment. A zirconia primer was applied to the surface of the zirconia specimens. Composite disks were bonded using a resin cement and light-cured. The specimens were stored in 37°C distilled water for 24 hours and thermocycled for 2,500 cycles. The specimens were loaded in shear on a universal testing machine. Data were analyzed with one-way and two-way ANOVAs and Tukey's post hoc tests (α = 0.05). A significant difference in shear bond strength was found based on the surface treatment (p < 0.001), but not on the type of zirconia (p = 0.132). Air abrasion with glass beads or no surface treatment resulted in significantly lower bond strength of the resin cement to all three zirconia types compared to air abrasion with aluminum oxide. Although air abrasion with aluminum oxide may reportedly be more likely to weaken cubic-containing zirconia compared to air abrasion with glass beads, the use of aluminum oxide results in greater bond strength of the resin cement.

Bond strength of surface-treated novel high translucent zirconia to enamel

Aim: The aim of the present study was to evaluate the shear bond strength of zirconia, stabilised with 5% yttria, luted to enamel and to evaluate the fracture pattern at loss of retention.Methods: A total of 53 test specimen were manufactured from two partially stabilised zirconia materials, Zirkonzahn Prettau Anterior (ZPA) (n = 16) and Whitepeaks CopraSmile Symphony 5 layer (WCS) (n = 18), and a lithium disilicate (Ivoclar e.Max Press) (n = 19) acting as control. All test specimens were cemented to human enamel with Variolink Esthetic DC and then subjected to a shear bond strength test. Fracture and surface analysis were performed using light and scanning electron microscope.Results: No significant differences in shear bond strength were detected when analysing the three groups. Dividing them according to the fracture pattern significant difference in shear bond strength between the two zirconia groups could be seen analysing test bodies with failure of adhesion to the test body, but not to enamel. The ZPA had higher shear bond strength (23.68 MPa) than WCS (13.00 MPa). No significant differences were seen compared to the control group (19.02 MPa).Conclusion: Partially stabilised zirconia shows potential as a material to be used where macro mechanical bonding is not possible, although this study does not reveal how or if the bonding deteriorates over time.

Comparison of Shear Bond Strength of Two Commercially Available Bondable Molar Tubes

Introduction: Direct and indirect bonding has revolutionized clinical orthodontics by reducing chair-side time and enhancing patient comfort. Clinicians often hesitate to bond molars due to ambiguity on shear bond strength. This study was conducted to compare shear bond strengths of two commercially available bondable molar tubes. And asses mesh if the mesh design had a role to play in differences in shear bond strength.&#x0D; Materials &amp; Method: 30 extracted maxillary molars were divided into Group I and II (n=15).Group I bonded with Victory series MBT (3M Unitek). And Group II bonded with Ortho classic proprietary Pad- Lok (Navy orthodontics). Teeth were mounted on a jig and Shear Bond Strength was evaluated on an Instron universal testing machine at a cross head speed of 1mm/minute. They were also subjected to scanning microscopic examination to check the base pattern.&#x0D; Result: Shear bond strength of navy orthodontic tubes were (18.0675+/- 4.0187 MPa) was significantly higher than 3M victory series (8.93 +/2.493MPa). Unpaired T-test shows a higher significant difference in SBS between two groups at 1% of significance. SME showed that navy orthodontic tube base was pad-lock mesh design, while 3M was a single mesh base design.&#x0D; Conclusion: 3M victory series molar tube exhibited a near ideal while other sample showed far higher shear bond strength than recommended. Higher values may result in enamel fracture.

Perbedaan Kekuatan Geser Perlekatan (Shear Bond Strength) Antara Self – Adhering Flowable Composite dan Flowable Composite dengan Sistem Adhesif Self – Etch pada Dentin

Restoration is a treatment to restore the structure of missing dental hard tissue due to caries. Flowable composite has good adaptability to the cavity wall so that it is widely used as an intermediate layer. Composite resins require an adhesive system to bond chemically with dental hard tissue. Self - adhering flowable composite combining etching, priming, and adhesive in one flowable package. This study was conducted with the aim to determine the difference in shear bond strength between Self – adhering flowable composite and flowable composite with self – etch adhesive system on dentine. The number of samples used was 38 pieces. After dentin was prepared and fixed, samples was divided into 2 groups, each group consisting of 19 samples. First group was applied with self – adhering flowable composite, second group was applied with flowable composite with self – etch adhesive system. Samples was immersed in pH 6.8 normal saline and stored for 24 hours, then dried and shear bond strength was tested using a universal testing machine. The data obtained were analyzed using independent t – test. The statistical analysis using independent t – test showed that there were significant differences in the shear bond strength between the two groups, p=0,000 (p&lt;0.05). The study concluded that there is difference of shear bond strength between self – adhering flowable composite and flowable composite with self – etch adhesive system on dentine.

SHEAR BOND STRENGTH OF BISPHENOL A-GLYCIDYL METHACRYLATE ADHESIVE RESIN AFTER APPLICATION OF EUCALYPTUS OIL BEFORE DEBONDING METALLIC ORTHODONTIC BRACKET

Objective: Debonding of orthodontic braces could lead to enamel fracture and moderate discomfort for the patients. This study was conducted toexamine whether eucalyptus oil and eucalyptol were effective in decreasing the shear bond strength and facilitate the debonding of metallic bracketsbonded with bisphenol A-glycidyl methacrylate (bis-GMA) adhesive resin.Methods: Thirty upper premolar teeth were randomly divided into the following three groups: Group 1 (75% eucalyptus oil), Group 2 (100%eucalyptol), and Group 3 (aquades; controls). Gemini brackets (3M Unitek, Monrovia) were bonded to the teeth using Transbond XT (3M Unitek,Monrovia). The areas around the brackets were lubricated with 75% eucalyptus oil, 100% eucalyptol, and aquades for 10 min before debonding.Results: A significant difference in shear bond strength between Group 2 and the control group was noted (p&lt;0.05).Conclusion: The findings of this study indicated that eucalyptol can decrease the shear bond strength of bis-GMA-based adhesive resin after 10 minof application.