Effect of adhesive application on the shear bond strength using different cementing agents in molar and premolar attachments

Objectives: The purpose of the study was to evaluate the effect of adhesive application on the shear bond strength (SBS) of orthodontic brackets and tubes to acid-etched human enamel when using different cementing agents. Study Design: One hundred and sixty metal attachments (80 tubes and 80 brackets) were bonded to human third molars and premolars that were randomly divided into identical groups of four: Transbond XT (XT); Wave MV Flow (WF); APC Plus System (APC); and Fuji Ortho LC (LC). For each experimental group, half of the specimens were bonded in combination with Transbond XT adhesive. After 72?h, a SBS test was performed using a universal testing machine. Statistical analysis was performed using ANOVA with Bonferroni post hoc comparisons, χ² tests, and linear regression modeling. Adhesive remnant index scores were determined for the teeth after failure. Representative tooth surfaces from each subgroup were assessed under SEM. Results: Considering that each cement was observed, each of them showed similar SBS when the adhesive system was applied as when the adhesive was not applied. By comparing all cements together, it was noted that if an adhesive is not applied, all cements have similar values. If an adhesive is applied, cement XT, WF, and APC showed significantly higher SBS values than LC did. The tubes showed higher SBS than the brackets did in cements XT and WF with or without an adhesive, as well as APC Plus with an adhesive. Conclusions: The use of an adhesive system in bonding brackets and tubes does not influence the SBS obtained, independently of the cement.     

Effect of adhesive application on the shear bond strength of refrigerated and pre-heated of different composite resins to orthodontic molar tubes

Objective: To evaluate the effect of adhesive application on the shear bond strength (SBS) of orthodontic tubes to acid-etched human enamel using different temperatures and orthodontic composite resins. Methods: One hundred and twenty metal tubes were bonded to human third molars, which were randomly divided into three groups depending on the composite used: Transbond XT (XT); Transbond Supreme LV (LV); and Light Bond (LB). Each group was divided into four subgroups depending on the temperature (5°, 20°, 40°, and 60°) applied to the composite before cementing. For each experimental subgroup, half the specimens were bonded in combination with XT Primer. After 72?h, a SBS test was performed using a universal testing machine. Statistical analysis was performed using ANOVA, post hoc intergroup comparisons, chi-square test, and linear regression. Two representative molar surfaces from each subgroup were assessed under Scanning electron microscope. Results: The composite type only influenced XT regarding LB. The use of adhesive does not affect the SBS values of any composite. The flowable composites with adhesive containing zirconia (LV) as a filler showed lower SBS when cooled to 5?°C and when increases the temperature from 40?°C. Whether adhesive was used or not, composites with silica as filler (LB) showed lower SBS at 60?°C and increased to 5?°C. Conclusions: For all composites, from 20?°C, SBS values tend to increased and started to decline at 40°C except when adhesive is applied to the quartz-filled composite, which continues to increase, and the silica-filled composite without adhesive, which tend to decreases from 5?°C.     

Improvement of the Molar Tube Bond Durability with Preheated Orthodontic Adhesive

This study aimed to evaluate the effect of preheated orthodontic adhesives and thermal cycling on the bond strength of molar tubes. One hundred sixty molar tubes were bonded to acid-etched bovine incisors using a conventional orthodontic adhesive (Transbond XT), two microhybrid (Wave and Permaflo), and a nanofilled (Filtek Z350) flowable composite resins, at room temperature or preheated at 60°C. Transbond XT primer and Single Bond 2 adhesive system were used in association with Transbond XT and the flowable composites, respectively. The specimens were stored in water (37°C) for 24 h, and half of the sample was subjected to thermal cycling for 6000 cycles. Ashear bond strength (SBS) test was performed, followed by the appraisal of the adhesive Remnant Index (ARI). Three-way analysis of variance (ANOVA) and the Tukey test were performed at a significance level of 95% (P < .05). Samples bonded with preheated adhesives showed higher SBS regardless of the aging method. Only samples bonded with preheated conventional orthodontic adhesive maintained their bond strength after thermal cycling for 6000 cycles. Preheating orthodontic adhesives improved the bond strength of molar tubes, but only the preheated conventional orthodontic adhesive was capable of maintaining bond strength after thermal cycling.     

Effects of two metal primers on the shear bond strength of orthodontic molar tubes bonded to silver amalgam restorations of different dimensions

The aim of this study was to evaluate the shear bond strength (SBS) of orthodontic molar tubes bonded to amalgam restorations and enamel with four different area ratios, with and without the use of various metal primers. One hundred and fifty-six sound lower first molars were divided into five groups; control group (CG;n = 12) then divided into three subgroups: A, B, and C. Class V buccal amalgam restorations consisting of 25%(G1), 50%(G2), 75%(G3), and 100%(G4) of the basal areas of the molar tubes. Transbond XT Primer (TXTP;subgroup A), Alloy Primer (AP;subgroup B) and Reliance Metal Primer (RMP;subgroup C) (n = 12). Transbond XT was used as an adhesive material in all groups. Thermocycling was as 5 –55 °C, 1000 cycles. Data were analysed by one-way ANOVA and post hoc least significant difference tests (p < 0.05). Bond failure sites were classified using a modified Adhesive Remnant Index (ARI) system. SBS did not differ significantly among the three intermediate adhesives in subgroups of groups 1, 2, or 3 (p > 0.05); however, SBS was significantly higher in groups 4B and 4C than in group 4A (p < 0.05). Mean SBSs of groups 1 and 2 were significantly higher than others (p < 0.05). Mean SBS of group 3 was higher than that of group 4, but lower than that of the other groups. For ARI, significant relationships between CG and the intermediate adhesive groups were found (p < 0.05). Application of metal primers, such as AP or RMP, to sandblasted amalgam adjacent to etched enamel (25, 50, and 75%) did not improve bond strength significantly compared with the application of TXTP to amalgam and enamel.     

A novel silane system as a primer for orthodontic bonding—A pilot study

AimTo determine the adhesion strength (measured as shear bond strength, SBS) of orthodontic brackets using two experimental silane-based primer systems and compare and contrast their effect.Materials and methodsSixty acid-etched premolars were randomly assigned into 4 study groups (n=15). In group 1, brackets were bonded without primer but using Transbond XT adhesive; in group 2, Transbond XT primer was applied and bracket bonded; in group 3, an experimental silane-based primer of 1.0 vol% of 3-acryloxypropyltrimethoxysilane (ACPS) was applied before bonding; in group 4, an experimental silane-based primer of 1.0 vol% of ACPS+0.5% bis-1, 2-(triethoxysilyl) ethane (BTSE) was used. The adhesion strength (measured as shear bond strength) was recorded using a universal testing machine. Failure types were classified according to the Adhesive Remnant Index (ARI). Contact angles of the primers were measured on an enamel slab.Data was analyzed by ANOVA and Tukey's multiple comparison post hoc analysis.ResultsThe mean adhesion strength results were high in group 4: 15.8±1.6 MPa followed by group 3: 12.5±1.5 MPa, group 2: 11.9±1.1 MPa and the lowest in group 1: 08.1±0.7 MPa. A significant difference in adhesion strength was observed between all the groups except for group 3 and group 4 (p<0.01).The ARI score was distributed largely to 0 and 1. One instance of enamel fractures was recorded in group 1. The contact angle measurements suggested that the lowest value with the experimental primer containing (ACPS+BTSE) was, <5° followed by Transbond XT, 41.86±4.56°.ConclusionThe experimental silane primer systems were hydrophilic in nature and demonstrated higher adhesion strength compared to traditional orthodontic primers.     

Evaluation of antibacterial effects of contemporary orthodontic bonding materials

Aim: The aim of this study was to evaluate the antibacterial effects of five orthodontic bonding materials commonly used in orthodontics. Materials and Methods: The antibacterial effects of five orthodontic bonding materials were evaluated against Streptococcus mutans and Streptococcus salivarius by direct contact test (DCT). Using the DCT technique, quintet specimens of Transbond XT, Blugloo, Grengloo, Light Bond, and Opal Bond were applied to the bottom and the walls of the five wells of a 96-microtiter plate with a height of 2 mm. Samples were prepared in two sets: 1-day samples and 7-day samples. Ten microliters of bacterial suspension were added to each well for direct contact with each material for 1h at 37 °C. Bacterial growth was then measured in a microplate spectrophotometer hourly at 600 nm for 24 h. Five uncoated wells with identical inoculum sizes served as positive controls. The data obtained at the end of 24 h was statistically analyzed with one-way ANOVA, and post hoc comparisons were done using Tamhane’s T2 test. Results: Blugloo generally showed better antibacterial activity than the other materials. Transbond XT did not show any antibacterial activity. There was a statistically significant difference between Transbond XT and Light Bond in the 1-day sample against S. mutans (p < 0.05). No statistically significant differences were found among the other groups (p > 0.05). Conclusion: Blugloo had the most potent antibacterial activity against S. salivarious.     

Adhesion of orthodontic brackets to indirect laboratory-processed resin composite as a function of surface conditioning methods and artificial aging

This study compared the shear bond strength of orthodontic brackets to laboratory-processed indirect resin composites (IRC) after different surface conditioning methods and aging. Specimens made of IRC (Gradia Indirect, GC) (thickness: 2 mm; diameter: 10 mm) (N = 80) were randomly assigned to one of the following surface conditioning methods: C – Control: no treatment; AA – Air-abrasion (50 μm Al₂O₃ particles); DB – Diamond bur and HF – Etching with hydrofluoric acid (9.6%). After adhesive primer application (Transbond XT), orthodontic brackets were bonded to the conditioned IRC specimens using adhesive resin (Transbond XT). Following storage in artificial saliva for 24 h at 37 °C, the specimens were thermocycled (×1000, 5–55 °C). The IRC–bracket interface was loaded under shear in a Universal Testing Machine (0.5 mm/min). Failure types were classified using modified adhesive remnant index criteria. Data were analyzed using two-way ANOVA and Tukey`s HSD (α = 0.05). Surface conditioning method did not significantly affect the bond strength results (p = 0.2020), but aging significantly decreased the results (p = 0.04). Interaction terms were not significant (p = 0.775). In both non-aged and aged conditions, non-conditioned C group presented the lowest bond strength results (MPa) (p < 0.05). In non-aged conditions, surface conditioning with DB (8.03 ± 0.77) and HF (7.87 ± 0.64) showed significantly higher bond strength results compared to those of other groups (p < 0.05). Thermocycling significantly decreased the mean bond strength in all groups (2.24 ± 0.36–6.21 ± 0.59) (p < 0.05). The incidence of Score 5 (all adhesive resin remaining on the specimen) was the highest in HF group without (80%) and with aging (80%) followed by DB (40, 70%, respectively). C groups without and with aging showed exclusively Score 1 type (no adhesive resin on the specimen) of failures indicating the least reliable type of adhesion.     

Shear Bond Strength Evaluation of Orthodontic Brackets Bonded to Fluorotic Teeth with a Self-Etching Primer and a New Generation of Color Bonding

The objective of this work was to evaluate the shear bond strength (SBS) and bond failure site of brackets bonded to teeth with fluorosis treated with and without microabrasion before placement of a self-etching primer (SEP) and a color-changing composite and to compare with a control group. This in vitro study included 120 premolars with and without dental fluorosis, divided into six groups: (1) healthy enamel etched for 15 sec and fifth generation primer, (2) healthy enamel, (3) mild fluorosis (MIF) enamel, (4) MIF enamel microabraded, (5) moderate fluorosis (MOF) enamel, and (6) MOF enamel microabraded. For groups 2–6, an SEP was used. All samples were evaluated with the SBS test and the modified adhesive remnant index (ARI). The highest SBS mean value was for healthy enamel etched for 15 sec and fifth generation primer and the lowest SBS mean value was for healthy enamel with SEP. Significant differences were found in the ARI between healthy and MOF groups. SBS of orthodontic brackets bonded on fluorotic teeth with an SEP and a new generation of color bonding could be clinically acceptable as the value obtained was above the suggested minimum required for orthodontic bonding.     

Effects of sodium ascorbate and delayed bonding after bleaching on shear bond strengts of orthodontic brackets

Introduction: The aim of the study was to determine the effects of sodium ascorbate and delaying bonding for 4 weeks after bleaching on SBS of orthodontic brackets.

Methods: Sixty freshly extracted, noncarious, premolars were randomly assigned to 4 groups of 15 each. Orthodontic brackets were bonded with a composite resin and cured with a halogen light. After bonding, the shear bond strengths of the brackets were tested with a universal testing machine. Group I served as the control. In groups II, III, and IV, teeth were bleached with an office bleaching method. In group II, brackets bonded immediately after bleaching. In group III, teeth were immersed in artificial saliva of 4 weeks after bleaching before bonding brackets. In group IV, teeth were treated with 10% sodium ascorbate after bleaching before bonding brackets.

Results: One-way analysis of variance indicated a significant difference between groups (P < .001). The highest values for SBS were measured in group I (11.92 ± 0.81 MPa). The SBS was significantly lower in groups II, III, and IV than in group I (P < .001). There was no statistically significant difference between groups III and IV.

Conclusions: Bleaching significantly reduced the SBS of orthodontic brackets on human enamel. If bleaching is mandatory, teeth should be treated with sodium ascorbate before bonding.     

Effects of enamel surface preparation on bonding strength of resin-modified glass ionomer cement: an in vitro study

The purpose of this study was to evaluate a more suitable and efficient preparation method of enamel surface and a safe duration of loading in orthodontics when bonding with resin-modified glass ionomer cement (RMGIC). 300 human premolars were divided into five groups: G0, etched–Transbond XT; G1, etched–moistened; G2, etched–dry; G3, unetched–moistened; and G4, unetched–dry. Using an universal testing machine, we measured shear bonding strength (SBS) and tensile bonding strength (TBS) at 30 min, 24 h, and 30 d post-bonding. The adhesive remnant index was evaluated using stereomicroscopy. The results showed that enamel surface etching significantly improved SBS and TBS of RMGIC. The moist environment could accelerate both of SBS and TBS, but not the final bonding strength. Etching with moistening was the best processing method with RMGIC. When using RMGIC on unetched enamel, the bonding surface should be moistened and loading time delayed. When evaluating mechanical properties of the adhesive materials, it seemed that the TBS was more reasonable and objective than the SBS.     

Do hemostatic agents affect shear bond strength and clinical bond failure rate of orthodontic brackets?

To evaluate the effects of different hemostatic agents on the shear bond strength (SBS) in vitro and clinical bond failure rate of orthodontic metal brackets in vivo. A total of 100 human premolar teeth were randomly divided into five groups: control, blood, Viscostat, hydrogen peroxide (H₂O₂), and epinephrine. Teeth were bonded with same light-cured adhesive and composite. After storage in distilled water for 24 h, thermal cycling was used as an aging procedure on all samples. The brackets were subjected to an SBS test at a speed of 0.5 mm/min until bracket debonding. SBS values and the adhesive remnant index were evaluated. Ninety-nine patients (52 female, 47 males) undergoing routine orthodontic treatment were recruited for this controlled clinical study at bonding stages. All patients with bleeding on the buccal surface of any premolar tooth or teeth at bonding were included in this study. Over 6 months, the bond failure rate was calculated. Data were analyzed using one-way analysis of variance (ANOVA) and Tukey’s post-hoc test (p < .05). The McNemar test was used to compare bracket-bond failure. ANOVA showed a significant difference (p < .001) between the groups. No significant differences were found between the hemostatic agent groups (p > 0.05) in the in vitro part. The lowest failure rate was obtained in the control group rather than the hemostatic agent groups during clinical follow-up (p < 0.05). Each of the hemostatic agents (Viscostat, H₂O₂, and epinephrine) can be used for bleeding management during the orthodontic bonding process. Epinephrine application showed a high bond-failure rate at clinical follow-up.     

Evaluation of a new test method to determine the failure mode and macro-shear bond strength of dental materials to metals

Objective: To compare the macro mean shear bond strength (SBS) and failure mode of three cements to two types of metal using mould-enclosed and non-enclosed cement specimens. Methods: Titanium and base metal cobalt-based substrates were finished with 50 μm aluminium oxide. Two resin-modified glass-ionomers (Riva Luting Plus, Fuji Plus) and one resin cement (RelyX Unicem) were prepared as per manufacturers’ instructions. Metal mould-enclosed and non-enclosed cement specimens with a bonding area diameter of 3.5?mm were prepared and stressed to failure using a 2 mm blunt edge shear knife at a cross-head speed of 1?mm/min to determine mean SBS. The shear knife was placed against the surface of the substrate. Failure analysis of the failed interface was performed with a stereo microscope at 40× magnification. Results: Two-way Analysis of Variance demonstrated a significant difference in mean SBS between materials (p?=?0.004) and cement (p?=?0.001). There was also a significant interaction between method and cement on SBS, F(2,?170)?=?7.209, p?=?0.003. Post hoc Tukey tests demonstrated no significant difference for either resinmodified glass-ionomer cements (RMGIC) (p?=?0.864, p?=?0.620) when comparing non-enclosed and mould-enclosed test methods bonded to titanium. There was however a significant difference (p?<?0.001) between the mean SBS obtained for the resin cement when comparing the non-enclosed and mould-enclosed test methods. For base metal, the RMGIC’s SBS was higher than resin cement but no difference was observed between one of RMGIC’s and the resin cement non-enclosed mean SBS. Although not the case for RMGIC’s bonded to titanium or one RMGIC bonded to non-precious cobalt-based metal, when comparing the test method on each cement, RMGIC and the resin cement showed significant differences between non- and mould-enclosed specimens mean SBS. In the non-enclosed specimen tests, 71% of all specimens tested exhibited adhesive failure, which was statistically different (p?<?0.001) to 91% for the mould-enclosed specimens. Failure mode was not always statistically different within groups, however non-enclosed specimens showed higher frequencies of mixed failures. Conclusion: Within the limits of this study, significant differences were found in comparing the mean SBS between mould-enclosed and non-enclosed specimens. A significant difference was found in failure mode between mould-enclosed and non-mould enclosed specimens. Mould-enclosed specimens bonded to metal exhibited a higher frequency of adhesive failure than non-mould enclosed specimens. Relevance: Mould-enclosed specimens used in place of non-enclosed specimens can be used in SBS testing to give a more valid result when bonding to metal.     

Effect of fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate on bond strength to enamel

To investigate the effect of fluoride varnish with added casein phosphopeptide-amorphous calcium phosphate on the shear bond strength (SBS) of two adhesive systems to enamel. Specimens obtained from permanent teeth were randomly distributed among four groups for enamel pretreatment [Control (no treatment, CNT), Duraphat varnish (DV), Clinpro White varnish (CWV), MI Varnish (MIV)], and each group was further divided into two subgroups according to adhesive [Etch&rinse (Adper Single Bond, ASB), self-etch (Clearfil SE Bond, CSE)]. Specimens were stored in distilled water at 37 °C for 24 h. Cylindrical composite specimens (2.3 mm in diameter, 3.0 mm in height) were then bonded to the enamel surfaces. SBS tests were performed and data were analyzed with two-way ANOVA and Tukey’s tests. For both CSE and ASB, SBS values of the CNT groups were significantly higher than those of all the enamel pretreatment groups (p < 0.05). Among the enamel pretreatment groups, SBS values with both adhesive systems were lowest in the MIV groups, followed by CWV and DV groups. In conclusion, pretreatment of enamel surfaces with fluoride-containing varnishes reduced bonding performance of adhesive systems to enamel. MIV appeared to cause greater enamel surface alterations and precipitation, which interfered with adhesive bonding mechanisms.     

Residual monomer release from orthodontic adhesives cured with different light sources

Introduction: The aim of this study was to evaluate the residual monomer release from orthodontic adhesives cured with light-emitting diode (LED) and halogen light sources.

Methods: Seven hundred and twenty stainless steel brackets were divided into 3 groups according to the adhesive system used (Transbond XT light-cure adhesive [TXT], Transbond LR capsule [LR], and Light Bond light-cure adhesive paste [LB]), and each group was divided into 2 subgroups according to light-curing procedure (LED or halogen). Brackets were bonded with adhesives onto tooth buccal surfaces and polymerized. Each specimen contained 24 brackets that simulated the oral environment (n = 5). The specimens were immersed in a 75% ethanol/water solution at 37 °C for 10 min, 1 h, 1 d, 7 d, 14 d, and 30 d, respectively. Eluted monomers (Bis-GMA, UDMA, and TEGDMA) were detected using HPLC.

Results: There was residual monomer release at all time periods, and the highest amount of release was observed cumulatively on the 30th day. The cumulative Bis-GMA released from adhesives was not different (p > 0.05). The cumulative TEGDMA released from adhesives was statistically different (p < 0.05). There was no statistical difference between QTH and LED light-curing units for each adhesive (p > 0.05).

Conclusions: The release of residual monomers stays at a high level for a long time after polymerization. The total leaching of residual monomers from the Light Bond light-cure sealant resin plus Light Bond light-cure adhesive paste was higher than that of other materials for both curing units. Different curing units (LED or QTH) did not affect the monomer release from the orthodontic adhesives.     

Effects of neutralizing or antioxidant agents on the consequences induced by enamel bleaching agents in immediate resin composite restorations

Purpose: Bleaching agents are claimed to impair the bonding to the tooth structure when resin composite restorations are immediately performed. This study aimed to evaluate the effect of a neutralizing solution (10% sodium bicarbonate) or an antioxidant agent (10% sodium ascorbate) on the immediate or delayed (15 days) shear bond strength (SBS) of composite restorations performed on enamel. Seventy flat buccal enamel surfaces obtained from bovine incisors were divided into seven groups (n = 10): control group, unbleached enamel, restored (3M ESPE/Adper Single Bond 2/Filtek Z350XT) (G1); bleached, immediately restored (G2); bleached, delayed restoration (G3); bleached, antioxidant (sodium ascorbate), immediately restored (G4); bleached, antioxidant, delayed restoration (G5); bleached, neutralizing (sodium bicarbonate), immediate restoration (G6); bleached, neutralizing, delayed restoration (G7). Specimens were submitted to SBS test and examined after failure using scanning electron microscopy (SEM). Results were statistically analyzed with ANOVA/Tukey’s tests (5%). Bonding to enamel immediately restored after bleaching (G2) was significantly lower than G1 (unbleached enamel; p < 0.05). Applying the antioxidant or neutralizing agent significantly improved the bonding to enamel compared with G2 (bleached, immediate restored), irrespective of the restoration time (immediate or delayed) (p < 0.05). No significance was found between the two agents when applied after bleaching, and compared with the control group, regardless of evaluation time (p > 0.05). SEM images demonstrated adhesive failures in the bleached, immediately restored group (G2). G3–G7 exhibited majority of cohesive and mixed failure patterns. 10% sodium bicarbonate or 10% sodium ascorbate neutralizes the negative immediate and delayed effects of bleaching on bond strength of enamel bleached enamel.     

Effect of different adhesive protocols on bond strength between composite resins for indirect use and repair materials

Abstract

The aim of this work is to evaluate the effect of different adhesive protocols on the bond strength (SBS) of composite resin for indirect use to repairs of bulk-fill or conventional nanoparticulated composites. Forty-eight cylindrical specimens of composite resin for indirect use were prepared, aged, and randomly divided into four groups (n?=?12), a control group without any adhesion protocol, and three experimental groups: Silane?+?Scotch Bond Multipurpose adhesive (S?+?SBMP), Tetric N Bond Universal (TBU), and Single Bond Universal (SBU). The treated surfaces were restored using two different composite resins: Filtek Bulk-Fill or Filtek Z350XT. Then, the specimens were submitted to the SBS test, and the resultant data were analyzed with ANOVA on ranks test and Tukey’s test (α?=?0.05). There were no significant differences between the two types of resins used as repair material. For both resins, the groups treated with S?+?SBMP obtained the highest values (p?<?0.001). Groups TBU and SBU did not have statistically significant differences between them. Pre-treatment with a silane coupling agent and a layer of a hydrophobic adhesive can improve the bond strength of repairs performed on a composite resin for indirect use.     

Influence of different surface treatments on zirconia/resin shear bond strength using one-bottle universal adhesive

ABSTRACT

This study was designed to evaluate the effect of different treatments on the zirconia/resin shear bond strength (SBS) using commercial one-bottle universal adhesive. Zirconia discs with different surface treatments (blank control; airborne-particle-abrasion; glazing) were bonded to the bovine enamel surfaces using one-bottle universal adhesive. All specimens were tested for SBS (MPa) before and after 10000 thermocycles. Statistically analysis were conducted by using one-way analysis of variance and multiple-comparison least significant difference tests (α = 0.05). Airborne-particle-abrasion group showed higher SBS (36.19 ± 11.86) than control group (14.98 ± 5.90) and glazing group (10.63 ± 5.39) (p < 0.05). After thermocycling test, the SBS significantly decreased for control group (8.84 ± 2.55) and glazing group (6.18 ± 2.78) while not for airborne-particle-abrasion group (41.5 ± 7.95). One-bottle universal adhesives combined with airborne-particle-abrasion showed quite high SBS of zirconia/resin, which was appropriate for bonding of zirconia restoration.     

Effects of surface treatments on the bond strength of composite resin to hybrid computer-assisted design/manufacturing blocks

The aim of this study was to evaluate the repair bond strength of a dimethacrylate-based composite to two hybrid CAD/CAM blocks after different surface treatments. One hunded and twenty specimens were prepared from two different CAD/CAM blocks (Lava Ultimate (L), Cerasmart (C)). After thermal aging, specimens from each group (n?=?60) were divided into 6 treatment groups (n?=?10): (1) No treatment (2) Phophoric acid (37%) for 60?s, (3) Hydrofluoric acid (8%) for 60?s, (4) Sanblasting with 50-µm aluminium oxide (5) Er,Cr:YSGG laser treatment at 2?W and (6) Er,Cr:YSGG laser treatment at 3?W. Single Bond Universal was applied on all specimens and a dimethacrylate-based composite (Tetric N-Ceram) was bonded using Teflon tubes. After thermal cycling, shear bond strength (SBS) was tested, and failure modes were evaluated. Two-way ANOVA and independent t-test were used for statistical analysis (p?<?0.05). The highest SBS values were detected at Er,Cr:YSGG laser treatment groups (3W) (L:22.7?MPa, C:22.6?MPa). Lowest SBS values were obtained at no surface pretreatment groups followed by phophoric acid treatment groups which were significantly lower than sandblasting, hydrofluoric acid treatment and Er,Cr:YSGG laser treatment groups (p?=?0.001). The universal adhesive Single Bond Universal had no effect on promoting bond strength to hybrid ceramics alone or with phosphoric acid. Sandblasting, hydrofluoric acid and laser treatment were effective at increasing repair bond strength, for both Lava Ultimate and Cerasmart.     

The shear bond strength of repaired high-viscosity bulk-fill resin composites with different adhesive systems and resin composite types

This study compared the effect of different adhesive systems and composite resins on the shear bond strength (SBS) of repaired high-viscosity bulk-fill composites(Tetric EvoCeram Bulk Fill) and investigated failure modes. One hundred twenty cylindrical bulk-fill composite blocks (diameter 5?mm) were fabricated and thermocycled for 5000 cycles (5–55?°C). Specimens were roughened by diamond bur and divided into 8 groups (n?=?15). Bulk-fill blocks were repaired with the same material or nanohybrid composite resin(Tetric EvoCeram Nanohybrid) (diameter 3?mm) using different adhesive systems:Tetric N-Bond Universal (TSE);37% phosphoric acid etching?+?Tetric N-Bond Universal (TER); Clearfil SE Bond (CSE); 37% phosphoric acid etching?+?Adper^TMSingle Bond 2(SB). After repair procedures, all specimens were thermocycled again. The shear bond strengths were measured for all specimens using a universal test machine (crosshead speed of 1?mm/min). Cohesive strengths of bulk-fill composites were measured and described as control group. Debonded surfaces were observed with a stereomicroscope under 10x magnification to determine mode of failure. The SBS data of all groups was statistically analyzed by two-way ANOVA and Bonferroni correction test (p?<?0.05). The specimens repaired with bulk-fill composites showed significantly higher SBS values (25.86?±?5.74, 27.05?±?4.93, 24.49?±?6.95MPa) than those with nanohybrid composites (20.41?±?3.70, 22.08?±?6.37, 18.74?±?6.40?MPa) for TER,CSE,SB, respectively (p?<?0.05). There were no significant differences in SBS according to the type of adhesive systems for both repair materials (p?>?0.05). The predominant mode of failure was a mixed type in the restorative material except for the ones repaired with nanohybrid composites using Adper^TMSingle Bond 2. High-viscosity bulk-fill composites could be successfully repaired with the same materials. SBS of repaired bulk-fill composites reached cohesive strength for all tested groups.     

Effect of cigarette smoking on the bond strength between resin cement and dental CAD/CAM ceramics

Although the effects of cigarette smoking on several dental problems have been widely studied, the association between tobacco exposure and resin-ceramic bonding is rarely reported. This study investigated the resin-ceramic adhesion (shear bond strength, SBS) and associated risk factors on three selected dental CAD/CAM ceramics using a novel model to simulate the exposure to cigarette smoking. Specimens from IPS e.max® CAD, Vitabloc® Mark II for Cerec and Zirconia Cercon were prepared and treated using silicacoating and silane. A layer of resin cement was applied on the treated ceramic surfaces and light activated. Specimens were placed in a chamber and challenged with various numbers of cigarettes (0, 1, 5, 10, and 15). Then, the specimens were subjected to SBS test and fractured surfaces were examined using scanning electron microscopy (SEM) and energy-dispersive X-ray spectrometry (EDX) to determine the failure mode and surface composition. Overall, the mean SBS of IPS e.max^® CAD (9.6 ± 3.4 MPa), Vitabloc^® Mark II for Cerec (9.3 ± 2.5 MPa) and Zirconia Cercon (8.7 ± 3.0 MPa) did not show any statistical significant difference (p = 0.192 > 0.05), such that the adhesion of resin bonded to glass-based ceramics (IPS e.max® CAD and Vitabloc® Mark II for Cerec) decreased with cigarette smoke exposure, but increased for the resin bonded to zirconia ceramic (Zirconia Cercon). Furthermore, the number of cigarettes has a statistically significant effect on the SBS (p = 0.001), such that in general 5 cigarettes yielded the lowest mean SBS (7.6 ± 2.1 MPa). SEM-EDX analyses showed mostly adhesive failures in all experimental groups with changes in surface morphology and chemical composition after smoking challenge. Cigarette smoking produces a different effect on resin-ceramic bonding depending on ceramic type that may be due to chemical reactions in the bonding interface and changes in temperature and moisture. Further work should explore the mechanism to which cigarette smoke affects the resin-ceramic bonding and its clinical relevance.