Shear Bond Strength Values Research Articles

Evaluation of the shear bond strength between CAD/CAM blocks and sonic/thermoviscous bulk-fill composites with different surface treatments

Background/purposeTo evaluate the shear bond strength (SBS) of nanoceramic hybrid CAD/CAM blocks with two bulk-fill composites in deep margin elevation following different surface pretreatments. Materials and methodsForty cylindrical-shaped samples (3 mm diameter × 4 mm height) were prepared from each group of bulk-fill resin composites (BRC) (SonicFill 3/SF, VisCalor bulk/VS), and 80 samples (14.5 mm × 7.2 mm × 2 mm) were sectioned from Grandio Block. Specimens of each BRC were assigned to two subgroups, and surfaces of one group were treated with a tribochemical silica-coating. The CAD/CAM block sample surfaces were treated with Al2O3 particles. CAD/CAM block and composite samples were luted using dual-cure universal resin-based cement (Bifix QM). Following immersion in distilled water for 24 h, the samples were divided as immediate and test groups. The test group was subjected to thermocycle (5–55 °C, 10,000 cycles). The SBS of the resin-based cement between the blocks and BRC was tested on a universal testing device until failure. Failure type was determined using a stereomicroscope. The roughening pattern was evaluated with SEM. Statistical analysis included Shapiro Wilk, Generalized Linear Models, and Fisher's Exact tests (P < 0.05). ResultsNo statistically significant difference was found between the mean SBS values according to deep margin elevation materials and surface pretreatment (P > 0.05). Aging procedure resulted in a statistically significant difference between the mean SBS values (P < 0.001). While the mean SBS value was 33.7 ± 7.9 MPa in immediate group, it was calculated as 22.6 ± 6.3 MPa in test group following thermocycle. ConclusionIn terms of SBS, both bulk-fill resin composites performed similarly. Although higher SBS values were obtained with tribochemical silica-coating, the adverse effects of thermocycling on bonding could not be prevented.

Effect of time and photoactivated face on bond strength of brackets and on degree of monomer conversion.

To evaluate the effect of four different photoactivation protocols (according to "photoactivated faces" - mesial/distal, cervical/incisal or center - and "photoactivation time" - 6-3s) of a high-power photo activator (Valo Cordless®-Ultradent) on the shear bond strength (SBS) between metal brackets and dental enamel and on the degree of conversion (DC) of an orthodontic resin. 40 bovine incisor crowns were randomly assigned to 4 groups (n = 10). The brackets were bonded with Transbond XT® resin using 4 protocols according to the "photoactivation protocol" factor (which was subdivided into photoactivated faces and photoactivation time): V3C = 3s + center; V6C = 6s + center; V3M3D = 3s on mesial + 3s on distal; V3C3I = 3s on cervical + 3s on incisal. All the samples were stored for 4 months (water,37ºC) and then subjected to a SBS test (100KgF,1mm/min). 40 resin discs were made to evaluate the monomer degree of conversion. Data from the SBS and DC were assessed by One-way ANOVA and Tukey's test (5%). Bond failures were analyzed according to the Adhesive Remnant Index (ARI) and evaluated by the Kruskal-Wallis test (5%). There was a statistically significant difference (p = 0.008) in the One-way ANOVA result for SBS values between all groups, but the protocols showed statistically similar results (p ≥ 0.05-Tukey's tests) concerning the photoactivated faces (V6C, V3M3D and V3C3I) and photoactivation time (V3C and V6C) factors individually. There was no statistically significant difference (p ≥ 0.05) in the One-way ANOVA result for DC values. The SBS and DC values will vary depending on the protocol applied. It is possible to maintain the bracket fixation quality with the use of a high-power LED photo activator associated with a shorter photoactivation time. However, it is assumed that not all types of protocols that might be applied will provide quality bonding, such as V3C, V3M3D and V3C3I, which may - depending on the SBS and DC values - affect the final treatment time, due to brackets debonding, or increase of possibility of damage to dental enamel during bracket removal. Clinical studies are suggested to confirm the hypotheses of this research.

An in vitro assessment of the influence of dentinal pretreatment with chlorhexidine, nonthermal atmospheric plasma, chitosan, and proanthocyanidins on shear bond strength to composite.

Dentin biomodification has been emphasized as a means of improving the bond between composite resin and tooth surface, consequently enhancing its longevity. To evaluate the shear bond strength (SBS) of dentin after pretreatment with 2% chlorhexidine (CHX), 2% chitosan, nonthermal atmospheric plasma (NTAP), proanthocyanidins (5% pine bark ((PB) and 5% bromelain). The study was designed as an in vitro investigation. Sixty extracted mandibular molars (n = 60) were gathered for this in vitro research. The teeth were decoronated to expose the dentinal surface. All samples have been etched with 37% phosphoric acid and then pretreated with respective dentin biomodifiers. Group I (control): No pretreatment was done, Group II: 2% CHX, Group III: NTAP, Group IV: 5% PB, Group V: 2% chitosan, Group VI: 5% bromelain. Specimens were evaluated for the SBS test, which was done under the instron universal machine at a speed of 1 mm/min after a bonding agent and composite build-up were applied. While Group I had the lowest SBS (10.391.59Mpa), Group V had the highest SBS (30.111.53 Mpa). Pretreatment of the dentin enhanced the SBS of dentin to composite. When utilized after etching, dentin biomodification increased all experimental group's bond strength in contrast to the control. The highest SBS values were recorded with 2% chitosan, followed by NTAP.

The effect of surface treatment and thermal aging on the bonding of clear aligner attachments to provisional resin-based material: shear bond strength analysis.

The aim of this study is to evaluate the effect of different surface treatments on the shear bond strength (SBS) of clear aligner attachments bonded to Bis-acryl provisional crowns. 120 cylindrical bisacrylic composite material (ProTemp type) specimens were prepared and divided into six groups (n = 20) based on surface treatment, control: (no treatment); super coarse grit diamond bur, carbide bur, alumina-blasting, non-thermal plasma treatment, and Er:YAG laser treatment. The features of treated surfaces were examined using scanning electron microscopy (SEM). A flowable composite resin (Transbond XT; 3M Unitek) was bonded to the specimens forming the attachment. Half of specimens were subjected to thermal cycling (5,000 cycles). SBS was measured before and after thermal cycling. Each specimen was loaded at the attachment/resin interface at a speed of 0.5 mm/min until failure. The nature of the failure was analyzed using the composite remnants index (CRI). Two-way ANOVA and Tukey HSD were used for data analysis α = 0.5. For CRI scores analysis, Kruskal-Wallis test and Dunn's multiple comparison were used as post-hoc test. SEM analysis showed that all surface treatments altered surface properties and increase surface bonding area. The specimens treated with plasma, Er:YAG laser, and alumina-blasting had higher SBS values before and after thermal cycling. In comparison to control plasma, Er:YAG laser, and alumina-blasting showed a significant increase in SBS (P < 0.001) while carbide and diamond bur groups showed no significant differences (P > 0.05). Thermal cycling significantly decreased the SBS of control, carbide bur, diamond bur, and Er:YAG laser while no significant effect of alumina-blasting and plasma group. Er:YAG laser and plasma groups significantly exhibited more dominance for scores 2 and score 3 and the absence of score 0. Alumina-blasting, Er:YAG laser, or non-thermal plasma surface treatments increased the shear bond strength between clear aligner attachments and resin-based restorations.

The effect of antimicrobial peptide-added adhesive resins on shear bond strength and the adhesive remnant index of orthodontic brackets

ObjectivesThe aim of this study was to evaluate the effect of in-vivo produced Nisin which is an antimicrobial peptide (AMP) added to adhesive resin on shear bond strength (SBS) and the adhesive remnant index (ARI) of orthodontic brackets.MethodsBacterial AMP was produced by fermentation and the ideal AMP/Bond concentration and antimicrobial efficacy of the mixture were tested. To evaluate the SBS and ARI scores of AMP-added adhesive resins, 80 maxillary premolar teeth extracted for orthodontic purposes were used and randomly assigned into 2 groups (n = 40). Group 1: Control Group (teeth bonded with standard adhesive resin); Group 2: Experimental Group (teeth bonded with AMP-added adhesive resin). Statistical analysis was performed using the SPSS package program and applying the Mann-Whitney U and Fisher’s exact tests. P < 0.05 was considered as statistically significant.ResultsNisin synthesized in-vivo from Lactococcus lactis (L. lactis) (ATCC 7962) bacteria was provided to form a homogenous solution at an ideal concentration To find the minimum AMP/Bond mixture ratio that showed maximum antimicrobial activity, AMP and Bond mixtures were tested at various concentration levels between 1/160 and 1/2 (AMP/Bond). As a result, the optimum ratio was determined as 1/40. The antimicrobial efficacy of Nisin-added adhesive resin was tested against Streptococcus mutans (S. mutans) (ATCC 35,688) and Lactobacillus strains (cariogenic microorganisms). AMP formed a 2.7 cm diameter zone alone, while 1/40 AMP-bond mixture formed a 1.2 cm diameter zone. SBS values of the teeth bonded with Nisin added adhesive (17.49 ± 5.31) were significantly higher than the control group (14.54 ± 4.96) (P = 0.004). According to the four point scale, Nisin added adhesive provided a higher ARI score in favour of the adhesive and tooth compared to the control group (ARI = 3, n = 20).ConclusionsNisin produced from L. lactis (ATCC 7962) had greater antimicrobial effects after mixing with adhesive bond against cariogenic microorganisms S. mutans (ATCC 35,688) and Lactobacillus strains. Nisin added adhesive increased shear bond strength (SBS) of orthodontic brackets and ARI scores in favor of adhesive & teeth.Clinical relevanceClinicians should take into account that using Nisin-added adhesive resin in orthodontic treatments can provide prophylaxis against tooth decay, especially in patients with poor oral hygiene.

Shear bond strength and adhesive remnant index evaluation of three different orthodontic adhesive systems using three different light curing times

BackgroundSuccess of long orthodontic treatment using orthodontic brackets depends mainly on the efficiency of the adhesive system used and it's degree of resistance in the face of stresses and foresees applied during treatment. The aim of this study was to evaluate the shear bond strength of orthodontic brackets bonded with three adhesive systems using different light curing times. Materials and methodsThe 126 human extracted premolars were randomly divided into three equal groups (n = 42) depending on the type of adhesive system used; total-etch (Transbond XT), self-etch (Transbond Plus), and self-adhesive (GC-Ortho Connect) system. Then each group was randomly subdivided into three subgroups (n = 14) based on the curing time; 1-s, 3-s, and 20-s. The shear bond strength (SBS) and adhesive remnant index (ARI) were evaluated in each subgroup using universal testing machine and stereomicroscope respectively. The data were analyzed statistically by a two-way ANOVA for SBS, and Scheirer Ray Hare Test for ARI. The significance level was set at P ≤ 0.05. ResultsThe results showed a statistically significant difference in shear bond strength at the three-time points for each adhesive system (p < 0.001) with the highest SBS value in 20-sec groups followed by 3-sec groups while 1-sec groups was the lowest. However, there was no statistically significant difference in Shear bond strength between the three adhesive systems except 20-sec groups (p < 0.001). ARI showed a statistically significant difference between all adhesive systems with the highest scores in TE groups, while the lowest in SE groups. ConclusionAll adhesive systems provided acceptable values of SBS at all curing times except the 1-sec group in SE and SA adhesive systems where the SBS values were the lowest and below the acceptable range.

Comparative evaluations of shear bond strength of mineral trioxide aggregate, Biodentine, and calcium-enriched mixture to bulk-fill flowable composite using three different adhesive systems: An in vitro study.

The objective of the study was to assess the shear bond strength of bulk-fill flowable composite resin smart dentin replacement plus when bonded to mineral trioxide aggregate (MTA)-angelus, biodentine, and calcium-enriched mixture (CEM) at two different aging periods (15 min and 72 h) using three distinct adhesive systems. In addition, the study identified the specific modes of failure (adhesive, cohesive, or mixed) using a stereomicroscope and scanning electron microscope. One hundred and twenty-six cylindrical acrylic blocks used in the study were sorted into three groups based on the bioactive substance used to fill the 3-mm diameter and 3-mm high hole in the center of each block. The groups were MTA, Biodentine, and CEM. The specimens were then divided into subgroups based on the aging interval (15 min and 72 h) of the bioactive material and the adhesive system used (two-step total-etch, two-step self-etch [SE], and one-step SE) while bonding to the restorative bulk-fill flowable composite. The shear bond strength values were measured with a universal testing machine, and the data were analyzed using two-way and one-way analysis of variance, followed by a post hoc test. The specimens were assessed under stereomicroscope and scanning electron microscope to characterize the mode of bond failure (cohesive, adhesive, or mixed). The study showed that the type of adhesive system and the time of bonding affected the shear bond strength of bulk-fill composite to the pulp capping agents (P < 0.05). For MTA, the highest bond strength was observed with two-step SE group at 15 min (18.16 ± 2.97 MPa) (P < 0.05). CEM exhibited the highest bond strength with two-step SE group at 72 h intervals (8.77 ± 1.76) (P < 0.05). The highest bond strength for biodentine group was observed with total-etch group (8.54 ± 1.35 Mpa) and two-step SE (8.19 ± 1.94 Mpa) bonded at 72 h interval (P < 0.05). The majority of the samples in the MTA group (29/42) and CEM group (20/42) showed a cohesive fracture, whereas Biodentine group (22/42) had an adhesive fracture in most of its samples. MTA demonstrated the highest bond strength with two-step SE group at 15 min, and CEM exhibited the highest bond strength with two-step SE groups at 72 h interval. For biodentine group, the type of adhesive used did not impact the bond strength values.

Effects of Endodontic Irrigants on Shear Bond Strength of Mild Universal Adhesives to Dentin

PurposeThe objective of this in vitro study was to evaluate the shear bond strength (SBS) of several universal adhesives to dentin treated with sodium hypochlorite (NaOCl), and NaOCl followed by ethylenediaminetetraacetic acid (EDTA). Materials and MethodsAdhese Universal, Scotchbond Universal, Prime & Bond Elect, Prime & Bond Active, and Optibond XTR were included in the study. SBS values were determined in self-etch mode with no pretreatment of the dentin, after a 20-minute exposure of the dentin to 6% NaOCl, and after a 20-minute exposure to NaOCl followed by a one-minute exposure to 17% EDTA. Experimental groups were repeated using a total-etch technique (except Optibond XTR). ResultsAdhesives in self-etch mode had significantly reduced SBS following dentin exposure to NaOCl (P < .05), while with a total-etch technique, only Prime & Bond Active was affected (P < .05). SBS in self-etch mode when NaOCl exposure was followed by EDTA were equal to or higher than negative control values (P < .05). For total-etch groups, Adhese Universal was negatively affected by NaOCl + EDTA exposure (P < .05). Prime & Bond Elect exhibited lower SBS following NaOCl + EDTA exposure when compared to just NaOCl exposure but was not different from the negative control (P < .05). ConclusionFor the adhesives tested, the use of 17% EDTA following NaOCl exposure negated the negative effects of NaOCl on SBS in self-etch mode. When used in total-etch mode, results varied significantly, with some adhesives performing better or worse depending on the specific testing condition.

Comparative evaluation of bond strength and color stability of polyetheretherketone and zirconia layered with indirect composite before and after thermocycling: An in vitro study.

This study investigates the interaction of zirconia and polyetheretherketone (PEEK) with indirect composite in fixed dental prostheses. This investigation aimed to assess the shear bond strength (SBS) and color stability of zirconia and PEEK before and after aging, addressing critical concerns in dental restorative applications. The current in vitro study used 96 samples, 48 of which were divided into two groups, zirconia and PEEK, before and after thermocycling. A dual-axis chewing simulator was used for thermocycling. SBS was measured using a universal testing machine, and color stability was checked using a reflective spectrophotometer. Ninety-six samples were categorized into zirconia and PEEK groups, each with subgroups undergoing thermocycling. Samples were prepared using computer-aided design/computer-aided manufacturing milling and veneered with composite resin. Thermocycling involved 10,000 cycles, simulating stress levels equivalent to approximately 1 year of clinical use. SBS was assessed using standardized tests. Stereomicroscopic analysis was performed to evaluate the type of failure. Color stability of the core materials with indirect composite was done using a spectrophotometer before and after aging. Statistical analysis included paired t-tests and independent t-tests in SPSS software. The results revealed that SBS values for composite on PEEK decreased from 13.86 ± 0.164 MPa before thermocycling to 13.46 ± 0.185 MPa after thermocycling, with a significant difference (P < 0.005). However, both pre- and postthermocycling values for PEEK were higher than zirconia. The t-test confirmed the lower bond strength of composite to zirconia, with a noteworthy improvement after aging. Stereomicroscopic images revealed adhesive failure for the zirconia group and mixed (adhesive and cohesive) failure for the PEEK group. ΔE values were 3.21 ± 0.127 and 2.93 ± 0.142 for zirconia and PEEK groups, respectively (P < 0.005). Within the limitations of this study, it can be deduced that PEEK is a feasible substitute for zirconia when used in conjunction with indirect composite for the fabrication of dental prostheses.

Effect of Different Primers on the Shear Bond Strength of Orthodontic Brackets Bonded to Reinforced Polyetheretherketone (PEEK) Substrate.

This in vitro study assessed the effect of different primers on the shear bond strength (SBS) and adhesive remnant index (ARI) of orthodontic brackets bonded to reinforced polyetheretherketone (PEEK) substrate. A total of 40 specimens were randomly distributed to two groups based on the primer used for orthodontic bonding: group 1 (control)-Transbond XT adhesive with Visio.link primer and group 2 (test)-orthodontic adhesive (Transbond XT) with traditional orthodontic primer. After bonding, specimens were thermocycled followed by SBS testing and ARI scoring of debonded specimens. Data were analyzed using the unpaired independent t-test and the Chi-square test. Group 1 specimens showed significantly higher SBS values (21.38 ± 1.48 MPa) compared to group 2 specimens (18.63 ± 1.29 MPa) (p < 0.0001). Adhesive remnant index scores showed no significant variations in bond failure modes and distributions between groups. The SBS obtained by the tested primers exceeded the clinically recommended value. Consequently, there is a comparable clinical application for both tested primers in orthodontic bonding, especially the traditional orthodontic primer, where the availability of Visio.link in clinical practice is not ensured.

Effect of surface treatment strategies on bond strength of additively and subtractively manufactured hybrid materials for permanent crowns

ObjectivesThe purpose of this study is to evaluate the bond strength of different computer-aided design / computer-aided manufacturing (CAD/CAM) hybrid ceramic materials following different pretreatments.MethodsA total of 306 CAD/CAM hybrid material specimens were manufactured, n = 102 for each material (VarseoSmile Crownplus [VSCP] by 3D-printing; Vita Enamic [VE] and Grandio Blocs [GB] by milling). Each material was randomly divided into six groups regarding different pretreatment strategies: control, silane, sandblasting (50 μm aluminum oxide particles), sandblasting + silane, etching (9% hydrofluorics acid), etching + silane. Subsequently, surface roughness (Ra) values, surface free energy (SFE) were measured. Each specimen was bonded with a dual-cured adhesive composite. Half of the specimens were subjected to thermocycling (5000 cycles, 5–55 °C). The shear bond strength (SBS) test was performed. Data were analyzed by using a two-way analysis of variance, independent t-test, and Mann-Whitney-U-test (α = 0.05).ResultsMaterial type (p = 0.001), pretreatment strategy (p < 0.001), and the interaction (p < 0.001) all had significant effects on Ra value. However, only etching on VSCP and VE surface increased SFE value significantly. Regarding SBS value, no significant difference was found among the three materials (p = 0.937), while the pretreatment strategy significantly influenced SBS (p < 0.05). Etching on VSCP specimens showed the lowest mean value among all groups, while sandblasting and silane result in higher SBS for all test materials.ConclusionsThe bond strength of CAD/CAM hybrid ceramic materials for milling and 3D-printing was comparable. Sandblasting and silane coupling were suitable for both millable and printable materials, while hydrofluoric etching should not be recommended for CAD/CAM hybrid ceramic materials.Clinical relevanceSince comparable evidence between 3D-printable and millable CAD/CAM dental hybrid materials is scarce, the present study gives clear guidance for pretreatment planning on different materials.

Assessment of the Additive Effect of Remineralizing Agents in Combination With Fluoride Releasing Adhesives in the Prevention of Enamel Decalcification in Orthodontic Patients: An In Vitro Study.

Introduction Incorporation of remineralizing agents with fluoride-releasing bracket adhesives may prevent the development of white spot lesions (WSL) or reverse the established WSL in patients undergoing fixed orthodontic treatment. We aimed to find out how effectively casein phosphopeptide-amorphous calcium phosphate (CPP-ACP) and fluoride varnish (FV) can remineralize teeth when mixed with fluoride-releasing orthodontic adhesive. Materials and methods We randomly assigned a total of 60 premolar teeth, therapeutically extracted for orthodontic purposes, into two equal groups. Group I (n = 30) utilized fluoride-releasing adhesive (FR), and Group II (n = 30) bonded with non-fluoride adhesive (NFR). Based on the applied remineralizing agent, we further divided each of the two groups into three equal subgroups of 10: Group IA (FR+FV), Group IB (FR+CPP-ACP), Group IC (control-only FR), Group IIA (NFR+FV), Group IIB (NFR+CPP-ACP), and Group IIC (control-only NFR). Following bonding procedures, all the samples underwent pH cycling for 28 days, where the enamel samples were immersed in 20 ml of demineralizing solution for three hours, followed by immersion in 30 ml of remineralizing solution for 17 hours. The samples were analyzed for shear bond strength (SBS) on a universal testing machine and hardness values (HV) by the Vickers microhardness test (VMT) using the indentation method. We also evaluated the adhesive remnant index (ARI) scores to determine the site of bracket failure. Statistical analysis The shear bond strength (SBS) and hardness value (HV) were expressed as the mean, standard deviation (SD), and median for each subgroup. We used the non-parametric Kruskal-Wallis test to analyze the SBS and HV, followed by the Dunn-Bonferroni test for intra-pair differences. The ARI score was expressed as the frequency of the percentage distribution, and the difference in the distribution of ARI scores between the groups was assessed by the Cochran chi-square test. The probability (p) value equal to or less than 0.05 was considered statistically significant. Results The results show that Group IB, bonded with a fluoride-releasing adhesive and a CPP-ACP remineralizing agent surface treatment, has the highest HV of300.23 units. Group IIC (only NFR) has the lowest hardness of153.3 units, which is statistically significant (p < 0.001). However, the ARI scores are not statistically significant between the groups tested. Conclusion The bond strength of the adhesive and the surface hardness of the enamel increased with the addition of fluoride varnish and CPP-ACP to both the fluoride-releasing and non-fluoride-releasing adhesives.

Effects of different plasma treatments on bonding properties of zirconia

This in vitro study was to evaluate the effect of different non-thermal atmospheric pressure plasma (NTP) on shear bond strength (SBS) between yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) and self-adhesive resin cement. In this study, The Y-TZP specimens were divided into 4 groups according to the surface treatment methods as follows: Control (no surface treatment), Sb (Sandblasting), AP(argon NTP), and CP(20 % oxygen and 80 % argon combination NTP). Y-TZP specimens were randomly selected from each group to observe and test the following indexes: scanning electron microscope to observe the surface morphology; atomic force microscope to detect the surface roughness; contact angle detector to detect the surface contact angle; energy spectrometer to analyze the surface elements. Then, resin cement (Rely X–U200) was bonded to human isolated teeth with Y-TZP specimens to measure SBS. The results showed that for the SE test, the NTP group was significantly higher than the control group (p < 0.05). The results of the SBS test showed that the SBS values of the NTP group were significantly higher than those of the other groups, regardless of the plasma treatment (p < 0.05). However, there was no significant difference between groups AP and CP in a test of SBS (p > 0.05). This study shows that non-thermal atmospheric pressure plasma can improve the shear bond strength of Y-TZP by increasing the surface energy. The addition of oxygen ratio to argon is more favorable to increase the shear bond strength and is worth further investigation.

Comparative Assessment of the Shear Bond Strength of Ceramic Brackets Bonded to the Enamel Surface with a Self-adhesive System.

Objectives: This study aimed to evaluate the shear bond strength of ceramic brackets bonded to the enamel surface using Vertise Flow, with or without the application of phosphoric acid. Materials and Methods: Forty-five extracted human premolar teeth were randomly assigned to three groups (N=15) based on the adhesive used for bonding: 1) Transbond XT, etch, and bond; 2) Vertise Flow; 3) Etch and Vertise Flow. After a 500-round thermocycling procedure, the shear bond strength was measured using a universal testing machine. The samples were then evaluated under a stereomicroscope to determine failure modes, and the Adhesive Remnant Index (ARI) was measured for each group. The data were analyzed with one-way ANOVA and post-hoc Tamhane at a significance level of P<0.05. Results: The highest shear bond strength values were observed in the Transbond XT (13.5±5.38MPa), acid etch and Vertise Flow (11.2±2.89MPa), and Vertise Flow (6.2±3.16MPa) groups, respectively, in descending order. The Vertise Flow group exhibited a significantly lower shear bond strength value compared to the other two groups, with no significant difference between the latter two. Conclusion: While all three study groups demonstrated clinically acceptable shear bond strength values, Vertise Flow showed lower values compared to the other two adhesives. The Vertise Flow composite resin system, whether used alone or with acid etching, remains a suitable choice for bonding ceramic brackets, offering the advantage of a simplified bonding procedure.

In Vitro Investigation of the Effects of Various Reducing Agents on Dentin Treated with Hydrogen Peroxide.

We assessed the effect of non-protein thiols (NPSH), reduced glutathione (GSH) and n-acetylcysteine (NAC), on resin shear bond strength (SBS) to hydrogen peroxide (H2O2)-treated dentin, and their effects on the characteristics of dentin in comparison to ascorbic acid (AA) and sodium thiosulfate (STS). H2O2-treated dentin was conditioned with 5% AA, GSH, NAC, or STS applied for 1 or 5 min. The positive control group received H2O2 without antioxidant application, and the first negative control group received distilled water (DW). The specimens received resin bonding immediately after treatment except for the second negative control group (delayed bonding). Microhardness, roughness, and topography were studied. The SBS values of all antioxidants were statistically greater than the positive control group (p < 0.05); however, NAC and AA applied for 1 min demonstrated the highest values, which were comparable to delayed bonding. All treatments removed the smear layer except DW, H2O2, and STS. The negative effect of H2O2 on resin-dentin bonding was mitigated by the application of the antioxidants; however, their efficiencies were dependent on the antioxidant type and time of application. NAC was more effective in optimizing resin bonding to bleached dentin compared to GSH at 1 min application and STS at both application times but was comparable to AA. Negligible negative effects on the substrate's roughness and microhardness were detected. The antioxidant properties of the agent and its capacity to remove the smear layer are the processes underpinning the ability of a certain antioxidant to reverse the effect of H2O2 on bonding.

In-Vitro Investigation of the Shear Bond Strength of Different Orthodontic Adhesives to Enamel.

The shear bond strength (SBS) of orthodontic adhesives to enamel is a critical factor in the success of orthodontic treatment. Various adhesives are available in the market, each with different trade names and claimed properties that could influence their bond strength. Understanding these differences is essential for clinical decision-making. In this in-vitro study, 60 freshly extracted human premolars were collected and randomly divided into four groups: Group A (Adhesive X-Trade Name: BondPlus), Group B (Adhesive Y-Trade Name: OrthoBond), Group C (Adhesive Z-Trade Name: PowerBond), and Group D (Control). The enamel surfaces were cleaned, polished, and etched following standard protocols. Orthodontic brackets were bonded to the teeth using the respective adhesives according to the manufacturer's instructions. A universal testing machine was employed to measure the SBS, and the data were analyzed using ANOVA with post-hoc tests. The mean SBS values (MPa) were as follows: Group A = 15.2, Group B = 14.8, Group C = 16.5, and Group D (Control) =10.3. Statistical analysis revealed significant differences among the groups (P < 0.05). Post-hoc tests indicated that Group C exhibited significantly higher SBS compared to the other groups. Our findings suggest that among the orthodontic adhesives tested, PowerBond demonstrated superior shear bond strength to the enamel. However, further research is warranted to explore other aspects of adhesive performance and clinical implications.

The impact of different surface treatments on repair bond strength of conventionally, subtractive-, and additive-manufactured denture bases.

This study aimed to examine the shear bond strength (SBS) of repair material to conventionally, subtractive-, and additive-manufactured denture bases after different surface treatments. Disk-shaped test specimens (N = 300) were prepared from denture base materials produced by one conventional (Procryla), one subtractive (Yamahachi), and one additive (Curo Denture) method. The test specimens were randomly divided into five groups (n = 10) and exposed to a variety of surface treatments-Group A: no surface treatment; Group B: grinding with silicon carbide paper; Group C: sandblasting; Group D: erbium: yttrium-aluminum-garnet laser; and Group E: plasma. Repair was performed with autopolymerizing acrylic resin (Meliodent). Surface roughness analyses were performed with a profilometer. Scanning electron microscopy was used to examine one specimen from each subgroup. SBS was evaluated on a universal testing machine. Failure types were observed under a stereomicroscope. Surface roughness values were significantly higher in all test materials in Group D than in the other groups (p < 0.001). For conventional resin, the SBS values were higher in Group C than in Groups A, D, and E (p < 0.001). For CAD/CAM material, Groups B and C had significantly greater SBS increases compared with Group E (p < 0.001). For 3D material, Group D showed higher SBS than all groups except Group C (p < 0.001). For SBS, sandblasting was most effective in the conventional group, whereas laser treatment was the most effective in the additive-manufactured group. For the subtractive group, surface treatments other than plasma exhibited similar SBS. In repairing fractured prostheses, any degree of roughening suitable for the material content may provide an SBS benefit.

The Effect of Different Chemical Surface Treatments on the Bond Strength of Resin-Matrix Ceramic Repaired with Resin Composite.

This study investigates the effect of different chemical surface treatment protocols with different functional monomers of universal adhesives on the shear bond strength between resin-matrix ceramic and resin composite. Eighty resin-matrix ceramics (Shofu block HC) were built and designed into eight groups of ten specimens and surface treated with HC primer (HC) and/or three universal adhesives (single bond universal [SBU], Scotchbond universal plus [SBP], and Tetric N-bond universal [TNU]) assigning follows; group 1, nonsurface treated; group 2, HC; group 3, SBU; group 4, HC + SBU; group 5, SBP; group 6, HC + SBP; group 7, TNU; group 8, HC + TNU. A template was put on the specimen center, and then pushed packable resin composite. Mechanical testing machinery was used to examine the samples' shear bond strength (SBS) values. To examine failure patterns, the debonded specimen surfaces were examined by a stereomicroscope. The one-way analysis of variance method was used to evaluate the data, and the Tukey's test was used to determine the significant level (p < 0.05). The highest SBS was obtained in group 6 (39.25 ± 1.65 MPa). Group 1 (4.15 ± 0.54 MPa) had the lowest SBS. Group 6 exhibited the highest percentage of cohesive failure patterns (70%). High SBS values were frequently correlated with the surface treatment groups and the cohesive failure patterns. The application of HC primer prior to the universal adhesive is an alternative protocol for enhancing the repair bond strength between resin-matrix ceramic and resin composite interfaces. Moreover, the application of HC primer prior to the SBP is the best strategy for resin-matrix ceramic and resin composite repairs.

Effect of Acid Surface Treatments on the Shear Bond Strength of Metal Bracket to Zirconia Ceramics

The surface treatment of zirconia prior to bonding remains controversial and unclear. This study aimed to compare the shear bond strength (SBS) of metal brackets to zirconia under surface treatments with either 4% HF or 37% PA in both immediate loading (IML) and artificial aging by thermocycling (TMC). Methods: Eighty-four zirconia were randomly assigned to six groups based on the surface treatment and artificial aging by TMC: (1) No surface treatment (NT); (2) NT + TMC; (3) HF (4% HF for 2 min); (4) HF + TMC; (5) PA (37% PA for 2 min); and (6) PA + TMC. After bracket bonding, only the TMC groups were thermocycled for 5000 cycles. The SBS and adhesive remnant index (ARI) of all groups were analyzed (p &lt; 0.01). Results: TMC significantly lowered the SBS more than the IML in all acid surface treatment groups (p &lt; 0.01). The ARI score after TMC was significantly higher than the IML in all acid surface treatment groups (p &lt; 0.001). No significant differences in the SBS values or ARI scores were observed among the surface treatments (p &gt; 0.01). Conclusions: Two-minute simple etching methods, using either 4% HF or 37% PA, showed an insufficient SBS of metal orthodontic brackets to zirconia after TMC.

Effect of surface treatment and resin cement type on the bond strength of polyetheretherketone to lithium disilicate ceramic

BackgroundThis study aims to evaluate the effect of surface treatment and resin cement on the shear bond strength (SBS) and mode of failure of polyetheretherketone (PEEK) to lithium disilicate ceramic (LDC). This is suggested to study alternative veneering of PEEK frameworks with a ceramic material.Methodseighty discs were prepared from PEEK blank and from lithium disilicate ceramic. Samples were divided into four groups according to surface treatment: Group (A) air abraded with 110 μm Al2O3, Group (AP) air abrasion and primer application, Group (S) 98% sulfuric acid etching for 60 s, Group (SP) Sulfuric acid and primer. Each group was subdivided into two subgroups based on resin cement type used for bonding LDC:1) subgroup (L) self- adhesive resin cement and 2) subgroup (B) conventional resin cement (n = 10). Thermocycling was done for all samples. The bond strength was assessed using the shear bond strength test (SBS). Failure mode analysis was done at 50X magnification with a stereomicroscope. Samples were chosen from each group for scanning electron microscope (SEM). The three-way nested ANOVA followed by Tukey’s post hoc test were used for statistical analysis of results. Comparisons of effects were done utilizing one way ANOVA and (p < 0.05).ResultsThe highest mean of shear bond strength values was demonstrated in Group of air abrasion with primer application using conventional resin cement (APB) (12.21 ± 2.14 MPa). Sulfuric acid groups showed lower shear bond strength values and the majority failed in thermocycling especially when no primer was applied. The failure mode analysis showed that the predominant failure type was adhesive failure between cement and PEEK, while the remaining was mixed failure between cement and PEEK.ConclusionThe air abrasion followed by primer application and conventional resin cement used for bonding Lithium Disilicate to PEEK achieved the best bond strength. Primer application did not have an effect when self-adhesive resin cement was used in air-abraded groups. Priming step is mandatory whenever sulfuric acid etching surface treatment is utilized for PEEK.