Effects of sterilization, conditioning, and thermal aging on the retention of zirconia hybrid abutments: A laboratory study

OBJECTIVE

To investigate the effects of sterilization, conditioning method, and thermal aging on the retentive strength of two-piece zirconia abutments.

MATERIALS AND METHODS

In total, 128 stock zirconia abutments were divided into four groups (n = 32) according to the conditioning parameters: (A) air-abrasion using 50 μm alumina particles/1.0 bar, (B) 50 μm/2.0 bar, (C) 100 μm/1.0 bar, and (D) 100 μm/2.0 bar. All abutments were bonded onto titanium bases using DTK adhesive resin and stored in water bath (37°C) for 72 h. Each group was subdivided into two subgroups (n = 16), group 1 was disinfected, whereas group 2 followed disinfection and autoclave sterilization. Half of the specimens of each subgroup (n = 8) was directly subjected to the axial retention test (groups N), while the other half was first subjected to 150 days of thermocycling followed by retention test (groups T). Statistical analysis was performed with three-way ANOVA, additional statistical analysis was performed by using separate one-way ANOVAs followed by the Tukey's post-hoc test for post hoc pairwise comparisons among groups.

RESULTS

The highest median retention strength was recorded for group B2N (1390 N), whereas the lowest strength was recorded for group C1T (688 N). No significant interaction (p ≥ 0.05) was detected between the different variables; conditioning method, sterilization, and the thermal cycling regarding the effect on the resulting retention. However, the sterilization always showed a positive effect. Thermocycling presented an adversely significant effect only in the absence of sterilization (p < 0.05), with the exception of subgroups A. For the sterilized groups, thermocycling had no statistically significant effect on the retention.

CONCLUSION

Steam autoclaving increased the retention of hybrid zirconia abutments. DTK adhesive resin for two-piece zirconia abutments performed well after sterilization and thermocycling.

Aluminum zirconate nanoparticles in etch and rinse adhesive to caries affected dentine: An in-vitro scanning electron microscopy, elemental distribution, antibacterial, degree of conversion and micro-tensile bond strength assessment

To incorporate different concentrations of Al2O9Zr3 (1%, 5%, and 10%) nanoparticles (NP) into the ER adhesive and subsequently assess the impact of this addition on the degree of conversion, μTBS, and antimicrobial efficacy. The current research involved a wide-ranging examination that merged various investigative techniques, including the application of scanning electron microscopy (SEM) for surface characterization of NP coupled with energy-dispersive x-ray spectroscopy (EDX), Fourier-transform infrared (FTIR) spectroscopy, μTBS testing, and microbial analysis. Teeth were divided into four groups based on the application of modified and unmodified three-step ER adhesive primer. Group 1 (0% Al2O9Zr3 NPs) Control, Group 2 (1% Al2O9Zr3 NPs), Group 3 (5% Al2O9Zr3 NPs), and Group 4 (10% Al2O9Zr3 NPs). EDX analysis of Al2O9Zr3 NPs was performed showing elemental distribution in synthesized NPs. Zirconium (Zr), Aluminum (Al), and Oxides (O2). After primer application, an assessment of the survival rate of Streptococcus mutans was completed. The FTIR spectra were analyzed to observe the characteristic peaks indicating the conversion of double bonds, both before and after the curing process, for the adhesive Etch and rinse containing 1,5,10 wt% Al2O9Zr3 NPs. μTBS and failure mode assessment were performed using a Universal Testing Machine (UTM) and stereomicroscope respectively. The μTBS and S.mutans survival rates comparison among different groups was performed using one-way ANOVA and Tukey post hoc (p = .05). Group 4 (10 wt% Al2O9Zr3 NPs + ER adhesive) specimens exhibited the minimum survival of S.mutans (0.11 ± 0.02 CFU/mL). Nonetheless, Group 1 (0 wt% Al2O9Zr3 NPs + ER adhesive) displayed the maximum surviving S.mutans (0.52 ± 0.08 CFU/mL). Moreover, Group 2 (1 wt% Al2O9Zr3 NPs + ER adhesive) (21.22 ± 0.73 MPa) samples displayed highest μTBS. However, the bond strength was weakest in Group 1 (0 wt% Al2O9Zr3 NPs + ER adhesive) (14.13 ± 0.32 MPa) study samples. The etch-and-rinse adhesive exhibited enhanced antibacterial activity and micro-tensile bond strength (μTBS) when 1% Al2O9Zr3 NPs was incorporated, as opposed to the control group. Nevertheless, the incorporation of Al2O9Zr3 NPs led to a decrease in DC. RESEARCH HIGHLIGHTS: 10 wt% Al2O9Zr3 NPs + ER adhesive specimens exhibited the minimum survival of S.mutans. 1 wt% Al2O9Zr3 NPs + ER adhesive samples displayed the most strong composite/CAD bond. The highest DC was observed in Group 1: 0 wt% Al2O9Zr3 NPs + ER adhesive.

Tensile bond strength of CAD-CAM all ceramic crowns before and after thermomechanical aging

PURPOSE

The purpose of this in vitro study was to compare the tensile bond strength (TBS) of resin nanoceramics (RNC), zirconia, and lithium disilicate (LS2) restorations cemented to titanium abutments before and after thermomechanical aging.

MATERIALS AND METHODS

Twelve specimens per group were fabricated to determine the TBS between a titanium abutment and four types of crown materials (2 RNCs, LS2, and translucent zirconia crowns for the maxillary molar). After milling, the abutments and crowns were cemented with resin cement after air-particle abrasion. In addition, thermomechanical aging (200,000 cycles, 50 N, 2 Hz) was applied to half of the specimens by using a mastication simulator. TBS was measured by using a universal testing machine. The interface between the crown and the cement was observed by using scanning electron microscopy (SEM). Two-way ANOVA was performed to analyze the effects of crown materials and thermomechanical aging. Failure-mode and interface analyses were also conducted.

RESULTS

After thermomechanical aging, the TBS decreased in the LS2 specimens and increased in RNCs (p < 0.001). The ratio of mixed failure and debonding with the hole-sealing resin increased in the RNC group. SEM images showed the reduced gap between the crown and the resin cement after thermomechanical aging in the RNC group.

CONCLUSIONS

Differences in TBS were affected by the crown materials after thermomechanical aging. After thermomechanical aging, the RNC crowns showed increased TBS, whereas LS2 and zirconia crowns exhibited decreased or similar TBS.

Three-Dimensional Printed Resin: Impact of Different Cleaning Protocols on Degree of Conversion and Tensile Bond Strength to a Composite Resin Using Various Adhesive Systems

The present investigation tested the effect of cleaning methods and adhesives on the tensile bond strength (TBS) of a resin-based composite luted to a temporary 3D printed resin. Substrates (n= 360) were printed using a Rapidshape D20II and cleaned with a butyldiglycol-based solution, isopropanol, or by centrifugation. Specimens were air-abraded with Al₂O₃ (mean particle size 50 µm) at 0.1 MPa followed by pretreatment (n = 30/subgroup) with: (1) Clearfil Ceramic Primer (CCP); (2) Clearfil Universal Bond (CUB); (3) Scotchbond Universal Plus (SUP) or 4. Visio.link (VL) and luted to PanaviaV5. TBS (n = 15/subgroup) was measured initially (24 h at 37 °C water) or after thermal cycling (10,000×, 5/55 °C). The degree of conversion (DC) for each cleaning method was determined prior and after air-abrasion. Univariate ANOVA followed by post-hoc Scheffé test was computed (p < 0.05). Using Ciba-Geigy tables and chi-square, failure types were analyzed. The DC values were >85% after all cleaning methods, with centrifugation showing the lowest. CCP pretreatment exhibited the lowest TBS values, with predominantly adhesive failures. The combination of CCP and centrifugation increased the TBS values (p < 0.001) compared to the chemical cleaning. CUB, SUP, and VL, regardless of cleaning, can increase the bond strength between the 3D printed resin and the conventional luting resin.

Marginal Micro-Seal and Tensile Bond Strength of a Biopolymer Hybrid Layer Coupled with Dental Prosthesis Using a Primerless-Wet System

The aim of this study is to compare the marginal seal and tensile bond strength (TBS) of prostheses fixed to enamel-dentin using different adhesive systems. Resin-composite inlays directly fabricated from Class V cavities of extracted human molars/premolars and mini-dumbbell-shaped specimens of bonded enamel-dentin were prepared for microleakage and tensile tests, respectively. Four adhesive systems were used: primerless-wet (1-1 etching for 10-, 30-, or 60-s, and 4-META/MMA-TBB), primer-moist (All-Bond2 + Duolink or Single-Bond2 + RelyX ARC), self-etch (AQ-Bond + Metafil FLO), and dry (Super-Bond C&B) bonding. Dye penetration distance and TBS data were recorded. Failure modes and characteristics of the tooth-resin interface were examined on the fractured specimens. All specimens in 10-, 30-, and 60-s etching primerless-wet, Super-Bond, and AQ-Bond had a microleakage-free tooth-resin interface. Primer-moist groups showed microleakage at the cementum/dentin-resin margin/interface. Significantly higher TBSs (p < 0.05) were recorded in primer-less-wet and Super-Bond groups with the consistent hybridized biopolymer layer after the chemical challenge and mixed failure in tooth structure, luting-resin, and at the PMMA-rod interface. There was no correlation between microleakage and TBS data (p = −0.148). A 1−3 µm hybrid layer created in the 10−60 s primerless-wet technique, producing complete micro-seal and higher tensile strength than enamel and cured 4-META/MMA-TBB, may enhance clinical performances like Super-Bond C&B, the sustainable luting resin.

Comparative Evaluation of Tensile Bond Strength of Poly Ether Ether Ketone (PEEK) and Zirconia Copings Using Resin Cement with or without Adhesive: An In Vitro Study

This in vitro research aimed to evaluate the Tensile Bond Strength of Poly Ether Ether Ketone and Zirconia copings using resin cement with or without Visio.link adhesive. From commercially available Zirconia and PEEK, blocks were machined milled using (CAD)/(CAM) to obtain 20 Zirconia and 20 PEEK copings. These specimens were sandblasted using 110 μm of alumina. The two main groups (20 Zirconia and 20 PEEK copings) were divided further into 4 subgroups, GROUP 1 (n = 10) PEEK substructure with self-adhesive resin cement without pretreatment, and GROUP 2 (n = 10) PEEK substructure with self-adhesive resin cement pre-treated with Visio.link adhesive. GROUP 3 (n = 10) Zirconia copings with self-adhesive resin cement without pretreatment. GROUP 4 (n = 10) Zirconia copings with self-adhesive resin cement pre-treated with Visio.link adhesive. Universal testing machine was used to evaluate the tensile bond strength of these copings. The results were analyzed using SPSS software Version 25.0 (SPSS Inc., Chicago, IL, USA). One-way ANOVA and independent t-test were used to compare the mean scores. Statistically significant increase was observed in Tensile Bond Strength of samples when Visio.link adhesive was used. Tensile Bond Strength of PEEK copings and Zirconia copings with Visio.link adhesive is considerably greater than PEEK copings and Zirconia copings without adhesive. The mean Tensile Bond Strength of Zirconia (with or without adhesive) is less as compared to Tensile Bond Strength of PEEK (with or without adhesive), but the difference is not statistically significant.

Evaluation of Tensile Bond Strength between Self-Adhesive Resin Cement and Surface-Pretreated Zirconia

The tensile bond strength between zirconia subjected to different surface-pretreatment methods and methacryloyloxydecyl-dihydrogen-phosphate (MDP)-containing self-adhesive resin cement was evaluated herein. Eighty-eight cylindrical zirconia specimens were randomly divided into the following four groups based on the pretreatment method: (1) no treatment, (2) air abrasion, (3) HNO3/HF etching, and (4) zirconia-nanoparticle coating. The tensile bond strength of the zirconia−resin-cement complexes was investigated. One-way ANOVA and post hoc tests were performed at a 95% significance level, and the Weibull modulus was calculated. Fracture patterns were visualized by SEM. The surface roughness of the specimens without resin bonding was evaluated by AFM. The tensile bond strength of the specimens decreased as follows: Groups 3 > 4 > 2 > 1 (28.2 ± 6.6, 26.1 ± 5.7, 16.6 ± 3.3, and 13.9 ± 3.0 MPa, respectively). Groups 3 and 4 had significantly higher tensile bond strengths (p < 0.05) and lower fracture probabilities than those of Groups 1 and 2. They also showed both mixed failure and resin-cement cohesive failure, whereas Groups 1 and 2 showed mixed failure exclusively. The zirconia−resin tensile bond was stronger after HNO3/HF etching or ZrO2-nanoparticle coating than after air abrasion or no treatment. The estimated surface roughness decreased as follows: Groups 3 > 4 > 2 > 1. The combination of zirconia pretreated with HNO3/HF etching or ZrO2-nanoparticle coating and an MDP-containing self-adhesive resin cement can increase the clinical longevity of zirconia restorations by preventing their decementation.

Influence of Simulated Oral Conditions on Different Pretreatment Methods for the Repair of Glass-Ceramic Restorations

PURPOSE

The present study investigated the influence of simulated intraoral conditions (increased temperature and humidity) on two different surface pretreatment methods to repair a lithium-disilicate glass-ceramic (LDS).

MATERIALS AND METHODS

A total of 540 rectangular lithium-disilicate glass-ceramic bars were manufactured (3 x 7 x 9 mm; IPS e.max CAD, Ivoclar Vivadent). Further specimen preparation was performed in an incubator with controlled relative humidity (RH) and temperature to simulate three different environmental settings: laboratory conditions (LC, n = 180, 23°C, 50% RH), rubber-dam conditions (RC, n = 180, 30°C, 50% RH) or oral conditions (OC, n = 180, 32°C, 95 ± 5% RH). One-third of the bars under each condition (n = 60) were grit blasted (GBL) with alumina (35 µm at 1 bar pressure for 10 s and a working distance of 4 ± 1 cm) and primed (60 s, Monobond Plus, Ivoclar Vivadent). Another third (n = 60) were pretreated with a self-etching glass-ceramic primer (MEP, Monobond Etch & Prime, Ivoclar Vivadent). One group without surface pretreatment (n = 60, NoPT) served as a control. All pretreated surfaces were coated with Heliobond (Ivoclar Vivadent). Two bars from the same pretreatment method were luted perpendicular to each other with a resin composite to form a square adhesion area of 9 mm2 (TetricEvo Ceram, Ivoclar Vivadent), and light cured for 20 s on each side (1200 mW/cm2, Bluephase 20i, Ivoclar Vivadent). All specimens were stored for 24 h in distilled water at 37°C. Half of the specimens from each environmental setting and pretreatment method (n = 15) were thermocycled (TC, 5000 cycles, 5/55°C, 30-s dwell time), and tensile bond strength (TBS) testing was performed for all groups using an x-bar rope-assisted set-up. Data were statistically analyzed using two-way ANOVA (a = 0.05) with Bonferroni adjustment.

RESULTS

Regardless of the environmental and storage conditions (24 h or TC), MEP showed a significantly higher mean TBS than GBL. A decrease in TBS was recorded in specimens under OC compared to RC and LC for both pretreatment methods independent of the storage condition. No significant difference in mean TBS was found between RC and LC within the MEP pretreatment group for the 24 h stored and thermocycled specimens. For all MEPs and GBLs, TC reduced the mean TBS in all environmental conditions. The NoPT groups showed no adhesion regardless of environmental or storage conditions.

CONCLUSIONS

Increased temperature and high humidity significantly reduced TBS. However, MEP was less sensitive to environmental influences than GBL, which makes it a promising candidate for intraoral ceramic repair. These findings suggest that clinical intraoral repair of lithium-disilicate glass-ceramics should be performed using a rubber-dam, primarily when using GBL.

Investigating Tensile Bonding and Other Properties of Yttrium Oxide Nanoparticles Impregnated Heat-Cured Soft-Denture Lining Composite In Vitro

Aims

This study was conducted to assess the effect of the addition of yttrium oxide (Y₂O₃) nanoparticles on the tensile bond strength, tear strength, shore A hardness, and surface roughness of soft-denture lining material.

Materials and Methods

Y₂O₃ NPs with 1.5 and 2 wt.% were added into acrylic-based heat-cured soft-denture liner. A total of 120 specimens were prepared and divided into four groups according to the test to be performed (tensile bond strength, tear strength, surface hardness, and surface roughness).

Results

There was a highly significant increase in tensile bond strength between the soft liner and the acrylic denture base, tear strength, and hardness at both concentrations as compared to the control group, whereas there was a nonsignificant difference between 1.5wt% of Y₂O₃ nanoparticles and the control group, and between 1.5wt% and 2wt% of Y₂O₃ nanoparticles. But there was a significant difference between 2wt% of Y₂O₃ nanoparticles and the control group.

Conclusion

The Y₂O₃ nanoparticles impregnated in soft-lining materials increased the mechanical properties of both tensile bonding strength and tear strength. Also, there was a significant increase in hardness but there was no change in surface roughness of acrylic-based denture soft-lining materials.

Soft Denture Liner Adhesion to Conventional and CAD/CAM Processed Poly(Methyl Methacrylate) Acrylic Denture Resins-An In-Vitro Study

This study aimed to evaluate the airborne-particle abrasion surface treatment effects on the tensile bond strength (TBS) between resilient denture liner and CAD/CAM or conventional heat polymerized poly (methyl methacrylate) (PMMA) acrylic denture resins. A total of 48 dumbbell-shaped specimens (70 mm in total length, and 12 mm and 7 mm in diameter at the thickest and thinnest section, respectively) were prepared from CAD/CAM and conventional acrylic resins. Before relining with denture liner, 12 specimens from each material were surface-treated by 110 µm Al₂O₃ airborne-particle abrasion, and the remaining specimens served as control (no treatment). Following relining, all the specimens were aged by thermal cycling (1000 cycles, 5–55 °C). The TBS of denture liner to acrylic denture resins was tested in a universal testing apparatus at a 5 mm/min crosshead speed. The debonded surfaces were visually examined for the failure modes. ANOVA and multiple comparisons posthoc analysis tests were applied to determine the significant difference in TBS between the study groups (α = 0.05). A significant difference in TBS was observed between the control and surface treated groups (p < 0.001) for both acrylic resins materials. However, there was no statistically significant difference in bond strength between the acrylic resins materials (p = 0.739). Surface treatment with airborne-particle abrasion demonstrated increased TBS of the soft denture liners to acrylic resins. The TBS of conventional and CAD/CAM acrylic resins to soft denture liners were not considerably different.

Evaluation of Tensile Bonding Strength of Permanent Soft Relining Material to Denture Base Acrylic Resin after Erbium:Yttrium- Aluminum-Garnet Laser Treatment - An in vitro Study

Purpose

The purpose of the study was to assess the effectiveness of erbium:yttrium-aluminum-garnet (Er:YAG) laser surface pretreatment at various pulse durations of exposure on increasing the tensile bonding strength of permanent soft relining material and acrylic resin.

Materials and Methods

Polymethyl methacrylate resin samples were fabricated and grouped as comparison group (no laser surface pretreatment) and three test groups (received Er:YAG laser surface pretreatment at various pulse durations of 10 s, 20 s, and 30 s) for bonding with the permanent soft relining material, Molloplast B. Following the surface pretreatment, the samples were tested for tensile stress using a universal testing machine. Loads at the point of failure were noted and the tensile bond strength values were obtained. Parametric tests of one-way-ANOVA and Tukey's post hoc tests were done.

Results

The highest tensile bonding strength was recorded in Group C, and the control group recorded the lowest bonding strength.

Conclusion

Er:YAG laser surface pretreatment at 10 Hz, 3 W, and 300 mJ for 30 s improved the bonding strength of the permanent soft relining material to heat-processed acrylic resin material.

An in vitro evaluation of tensile bond strength of soft liners bonded to different denture base resins

Background

Clinically, adhesion failure is the most critical problem because of the failure of the optimal bond between denture base and the soft liner.

Objectives

This study was performed to assess the tensile bond strength of two temporary soft liners to different denture base resins.

Materials and Methods

Forty-eight blocks with 16 samples each of heat-cured denture base resin of three different types were fabricated from custom-made stainless steel die after de-waxing mold space. Surface roughening of each acrylic resin specimens which bonds with soft liners was done by abrading the surface and to this temporary soft liners (Perma soft denture liner and Pro soft denture liner) were bonded. The universal testing machine was used to test the tensile strength of bonded space. The results were statistically analyzed using the Statistical Software IBM SPSS Statistics for Windows, version 20.0. (Armonk, NY, USA: IBM Corp.) using the Chi-square test, Post hoc Tukey's HSD, and two way ANOVA tests.

Results

It was observed that Perma soft was prevalent over Pro-soft denture liner on the basis of tensile bond strength with all three different types of denture base resins. Trevalon HI and acrylic composite exhibited better bond strength results with both Perma soft and GC Pro-soft denture liner as compared to other types of denture base resins.

Conclusion

Perma soft had a better bond strength compared to Pro-soft denture liner in bonding modified denture base and conventional resins.

The effect of acid concentration and etch time on morphology and tensile bond strength of primary dentin: An in vitro study

BACKGROUND

There are conflicting results concerning the ideal time for etching primary dentin and its effect on the bond strength of adhesive restorative materials.

AIM

To assess in vitro, the effect of varied acid concentration and etch time on the morphological features and tensile bond strength of primary dentin.

MATERIALS AND METHODS

Forty healthy primary molars were prepared by exposing the dentin of the occlusal surface, creating a smear layer. A 3 mm × 3 mm test indow was demarcated, and specimens were randomly allocated to four groups (n = 10): Group 1A 10% phosphoric acid, 7 s; Group 1B 10% phosphoric acid, 15 s; Group 2A 37% phosphoric acid, 7 s and Group 2B 37% phosphoric acid, 15 s. Surface analysis was done using atomic force microscope and scanning electron microscope. For tensile bond strength evaluation, 24 specimens prepared as mentioned were mounted in acrylic blocks and allocated to four groups according to the prescribed etching protocol. Resin rods were bonded and tested in tension after 24 h (n = 6). Data were analyzed statistically using unpaired t-test.

RESULTS

Etching of primary dentin using 37% phosphoric acid for 7 s produced the highest tensile bond strength of 9.51 ± 2.19 MPa.

CONCLUSION

Etching time of 7 s may improve the adhesion of resin restorative materials with primary dentin.

Efficacy of prototype endodontic obturators for novel root canal obturation techniques using a resin-based sealer in various powder-liquid ratios

PURPOSE

This study aimed to examine novel techniques using prototype endodontic obturators to obturate a resin-based sealer.

METHODS

Powder-liquid ratios of MetaSEAL Soft were changed to obtain suitable root canal sealing, and the physical properties for various powder-liquid ratios were analyzed according to ISO-6876. Tensile bond strength was also examined. Prototype endodontic obturators with a combination of thread numbers and pitch angles were analyzed for sealing ability after MetaSEAL Soft was obturated in simulated root canals.

RESULTS

Powder-liquid ratios of 1.0:1, 1.1:1, 1.2:1, and 1.3:1 showed suitable physical properties; however, flow for 1.4:1 was below a standard value. Tensile bond strength increased gradually when the powder-liquid ratio changed from 1.0:1 to 1.3:1, and 1.3:1 and 1.4:1 showed the highest and lowest bond strengths, respectively. Sealing ability increased when pitch angles of the obturators were 5°, 8°, and 11°; 11° showed the best results. Similarly, sealing ability increased when the thread number was 12, 17, and 22 pitches; 22 showed the best results.

CONCLUSION

These findings suggest that the prototype endodontic obturator can be useful for obturating MetaSEAL Soft, and a powder-liquid ratio of 1.3:1 MetaSEAL Soft may be the most suitable for achieving excellent sealing.

Bond Strength of Metallic or Ceramic Orthodontic Brackets to Enamel, Acrylic, or Porcelain Surfaces

Bonding strategies within different brackets and dental materials are still a challenge concerning adhesion and dental surface damage. This study compared the shear and tensile bond strength of orthodontic ceramic and metallic brackets to enamel, acrylic, and ceramic surfaces after thermal cycling. Dental surfaces were divided into three groups: enamel, ceramic, and acrylic. Each group received stainless-steel and ceramic brackets. After thermal cycling, specimens were randomly divided into two subgroups considering tensile (TBS) or shear bond strength (SBS) test. After the mechanical testing, scanning electron and optical microscopy were performed, and the adhesive remnant index (ARI) was determined. The two-way ANOVA full factorial design was used to compare TBS, SBS, and ARI on the surface and bracket type (α = 0.05). There were significant differences in TBS, SBS, and ARI values per surface (p < 0.001 and p = 0.009) and type of bracket (p = 0.025 and p = 0.001). The highest mean SBS values were recorded for a ceramic bracket bonded to an acrylic surface (8.4 ± 2.3 MPa). For TBS, a ceramic bracket bonded to acrylic showed the worst performance (5.2 ± 1.8 MPa) and the highest values were found on a metallic bracket bonded to enamel. The adhesion of metallic or ceramic brackets is enough for clinical practice although the damage of the enamel surface after debonding is irreversible and harmful for the aesthetic outcome of the teeth.

Effect of Incorporation of Silver Nanoparticles on the Tensile Bond Strength of a Long term Soft Denture Liner

OBJECTIVES

 This study aimed at assessing the effect of the addition of silver nanoparticles (SNPs) to a silicone soft liner on its tensile bond strength to denture base resin.

MATERIALS AND METHODS

 SNPs were added to Mucopren cold cure soft liner in 0 (control), 0.5, 1, 2, and 3 wt% concentrations and bonded in 120 stainless steel molds with processed heat cure acrylic resin blocks. Liner/resin combination samples were divided into two groups. The first half was stored for 2 days in distilled water at 37°C and then subjected to tensile bond strength, while the other half were thermocycled 3000 times before testing. Mean bond strength, expressed in mega pascals (MPa), was determined in the tensile test with the use of a universal testing machine at a crosshead speed of 5 mm/min.

STATISTICAL ANALYSIS

 Data were analyzed using SPSS via one-way analysis of variance test, t-test, and Tukey's posthoc, at a 95% confidence level (p < 0.05).

RESULTS

 Addition of SNPs and thermocycling both caused a significant reduction in the tensile bond strength of Mucopren to acrylic resin; however, in the thermocycled group, the bond strength increased with the increase in the concentration of SNPs (p < 0.001).

CONCLUSION

 Addition of SNPs to Mucopren soft silicone liner reduces its tensile bond strength to denture acrylic resin.

High-Performance Dental Adhesives Containing an Ether-Based Monomer

Dental adhesives are vital for the success of dental restorations. The objective of this study is to make strong and durable dental adhesives that are free from 2 symbolic methacrylate-based dental resins-2-bis[4-(2-hydroxy-3-methacryl-oxypropoxy)-phenyl]-propane (Bis-GMA) and 2-hydroxyethyl-methacrylate (HEMA)-and have equivalent/improved bonding strength and durability. We formulated, prepared, and evaluated 2 dental adhesives using mixtures of a hydrolytically stable ether-based monomer, triethylene glycol divinylbenzyl ether (TEG-DVBE), with urethane dimethacrylate (UDMA) or pyromellitic glycerol dimethacrylate. These adhesives were composed of equimolar ester-/ether-based vinyl functional groups. They were compared with Bis-GMA/HEMA-based commercial and experimental dental adhesives in terms of shear bond strength and microtensile bond strength (µTBS) to human dentin and the µTBS bond stability under extended thermocycling challenges. In addition, the resins' infiltration to dentin tubules, mechanical performance, and chemical properties were assessed by scanning electron microscopy, ISO standard flexural strength and modulus measurements, contact angle measurements, and water sorption/solubility measurements. The hybrid TEG-DVBE-containing dental adhesives generated equivalent shear bond strength and µTBS in comparison with the controls. Significantly, these adhesives outperformed the controls after being challenged by 10,000 thermocycles between 5 °C and 55 °C. Water contact angle measurements suggested that the hybrid dental adhesives were relatively more hydrophobic than the Bis-GMA/HEMA controls. However, both TEG-DVBE-containing adhesives developed more and deeper resin tags in dentin tubules and formed thicker hybrid layers at the composite-dentin interface. Furthermore, the water solubility of UDMA/TEG-DVBE resins was reduced approximately 89% in comparison with the Bis-GMA/HEMA controls. The relatively hydrophobic adhesives that achieved equivalent/enhanced bonding performance suggest great potentials in developing dental restoration with extended service life. Furthermore, the TEG-DVBE-containing materials may find wider dental applications and broader utility in medical device development.

The Effects of Surface Conditioning and Aging on the Bond Strength Between Composite Cement and Zirconia-reinforced Lithium-Silicate Glass-Ceramics

PURPOSE

To determine the effects of ceramic-surface conditioning and aging on the bond strength between composite cement and zirconia-reinforced lithium-silicate glass-ceramics (ZLS) under simulated clinical conditions.

MATERIALS AND METHODS

ZLS disks (Celtra Duo, Dentsply Sirona, n = 110 test group n = 10, diameter: 8.3 mm, height: 3.4 mm) were assigned to four surface-conditioning groups: (I) 30 s of ~5% hydrofluoric-acid etching (Vita Ceramics Etch, Vita; HF), silanization (Calibra Silane; SIL); (II) successive contamination with saliva and silicone (CONT), HF, SIL; (III) CONT, tribochemical silicatization (CoJet), SIL; (IV) HF, SIL, application and light polymerization of an adhesive (Prime&Bond Active), CONT, reapplication and light polymerization of the adhesive. The ZLS disks were bonded to composite-resin cylinders in acrylic tubes (inner diameter: 3.3 mm) using self-adhesive composite cement (Calibra Universal). The tensile-bond strength (TBS) was measured after both 24 h and 6 months of water storage (WS). Additional aging protocols were tested for group I (3-day WS; 30-day WS including 7500 thermocycles between 6.5 and 60°C; 150-day WS including 37,500 thermocycles).

RESULTS

After 24 h, the mean TBS ranged between 21 MPa (group III) and 30-35 MPa (remaining groups). With the exception of 3-day WS, TBS was statistically significantly reduced by aging. The greatest reduction was observed for silicatized specimens (group III, mean TBS after aging: 9.8 MPa).

CONCLUSION

Both ceramic surface conditioning and aging had a statistically significant effect on the bond strength between composite cement and ZLS. A treatment protocol based on tribochemical silicatization cannot be recommended for the adhesive cementation of ZLS.

Influence of Monomer Systems on the Bond Strength Between Resin Composites and Polymerized Fiber-Reinforced Composite upon Aging

PURPOSE

This study examined the influence of different monomer systems on the tensile bond strength between a resin composite and a polymerized fiber-reinforced composite (FRC). The influence of the age (shelf-life) of the FRC prepreg (reinforcing fiber pre-impregnated with a resin system) before preparing the FRC substrate for the bonding test was also assessed.

MATERIALS AND METHODS

Semi-interpenetrating polymer network (semi-IPN)-based glass FRC prepregs were aged for various durations (1, 1.5, and 3 years) at 4°C before being used to prepare FRC substrates via light polymerization. Four groups of aged prepregs were prepared through different treatments with: 1. no primer; 2. a dimethacrylate-based adhesive primer; 3. a universal primer; and 4. a specific composite primer. Subsequently, a resin composite luting cement was applied on the treated FRC substrates and cured with light. The water sorption of the FRC-composite specimens was determined. Then, the differences in the tensile bond strength were evaluated using ANOVA (p ≤ 0.05).

RESULTS

There were significant differences in the tensile bond strength between the composite cement and the FRC according to the primer used (p < 0.001), aging time (p < 0.001), and their interactive effect (p < 0.001).

CONCLUSION

The monomers of the universal primer demonstrated the best ability to diffuse into the semi-IPN structure of the polymer matrix of FRC. This improved the interfacial bond strength between the composite cement and the FRC substrate.

New Approaches in Bonding to Glass-Ceramic: Self-Etch Glass-Ceramic Primer and Universal Adhesives

PURPOSE

To investigate the tensile bond strength of silane-containing universal adhesives and self-etch glass-ceramic primer to lithium disilicate glass ceramics (LS2).

MATERIALS AND METHODS

960 rectangular LS2 bars (7 mm x 3 mm x 9 mm, IPS e.max CAD, Ivoclar Vivadent) were manufactured and divided into 4 groups (n = 240). Group 1 was etched with ~5% hydrofluoric acid (HF) for 20 s (VITA Ceramics Etch, Vita Zahnfabrik), group 2 was etched with ~5% HF for 20 s and silanized (ESPE Sil, 3M Oral Care), group 3 was pre-treated with a self-etching glass-ceramic primer (Monobond Etch & Prime, Ivoclar Vivadent, and group 4 received no pre-treatment. Three universal adhesives (iBOND Universal, Heraeus Kulzer; Scotchbond Universal Adhesive, 3M Oral Care; Futurabond U, Voco) were applied to the differently pre-treated surfaces, with Heliobond (Ivoclar Vivadent) serving as control. The bars from each group were paired and luted perpendicularly, forming a square bonded area of 9 mm2, using Variolink II (Ivoclar Vivadent) with a constant pressure of 10 N, followed by light curing (40 s at 800 mW/cm2, Elipar Trilight, 3M Oral Care). The resulting specimens were stored for 24 h at 37°C in distilled water. Half of the specimens of each group were submitted to tensile bond strength testing, the other half were thermocycled ([TC] 5000 cycles, 5°C/55°C, 30-s dwell time) before testing. Data were analyzed using three-way ANOVA (α = 0.05).

RESULTS

Group 2 (HF etched and silanized) and group 3 (self-etching glass-ceramic primer) reached significantly higher mean bond strengths than did groups 1 (only HF etched) and 4 (no pre-treatment).

CONCLUSION

Additional silanization of HF-etched LS2 statistically signficantly improved the tensile bond strength of the silane-containing universal adhesive (Scotchbond Universal). The self-etching glass-ceramic primer Monobond Etch & Prime achieved mean bond strengths that did not differ significantly from HF-etched and silanized specimens.

Efficacy of Various Surface Treatments on the Bonding Performance of Saliva-contaminated Lithium-Disilicate Ceramics

PURPOSE

To investigate the efficacy of different ceramic surface cleaning methods after saliva contamination on the resin bond strength to lithium disilicate ceramics.

MATERIALS AND METHODS

300 e.max CAD blocks (Ivoclar Vivadent) were polished with 600-grit silicon carbide paper and divided into five groups with or without human saliva contamination and according to the surface treatment performed (n = 10); control: no pretreatment; MP: Monobond Plus; PA+MP: 37% phosphoric acid (PA) followed by MP; HF+MP: 5% hydrofluoric acid (HF) followed by MP; MEP: Monobond Etch & Prime. The specimens were bonded with one of three resin cements: Variolink Esthetic DC (VE), Multilink Automix (MA) and Speed CEM (SC). After 24-h water storage, tensile bond strength (TBS) was measured. The ceramic surfaces after pretreatment were analyzed using x-ray photoelectron spectroscopy (XPS).

RESULTS

XPS analysis showed similar elemental distributions between saliva contamination vs no saliva in PA, HF, and MEP. The TBSs were significantly influenced by surface treatments (p < 0.05). HF+MP and MEP showed statistically non-significantly different bond strengths to saliva-contaminated HF+MP and MEP, but were different from MP and saliva-contaminated MP. The TBSs after 24 h were significantly higher in HF+MP and MEP groups with VE. HF+MP and MEP did not show statistically significant differences among any groups with or without saliva contamination.

CONCLUSION

Surface treatments with PA or HF followed by silane or by MEP alone were effective in removing saliva contamination and enhancing the resin bond strength.

Bonding Efficacy of 4-META/MMA-TBB Resin to Surface-treated Highly Translucent Dental Zirconia

PURPOSE

To evaluate the bonding efficacy of 4-META/MMA-TBB resin to highly translucent zirconia subjected to various surface treatments.

MATERIALS AND METHODS

Highly translucent zirconia specimens (Zpex Smile, Tosoh; 11.5 mm diameter, 5.0 mm thick) were mechanically pre-treated to improve micromechanical interlocking either by sandblasting with 50-µm Al2O3 particles (Kulzer Japan) or subjecting the specimens to a low-pressure plasma treatment (PM100, Yamato), or evaluated using the as-sintered surfaces as controls. Next, specimens from each condition were primed with an MDP-containing primer (PZ Primer, Sun Medical), while some remained unprimed. All specimens were bonded to stainless rods using 4-META/MMA-TBB resin (Super-Bond, Sun Medical). The specimens were stored in ultrapure water at 37°C for 24 h, after which a portion were subjected to 10,000 thermocycles. For all specimens (n=10/group) the tensile bond strength (TBS) was determined with a universal testing machine. The measured values were statistically analyzed using Weibull analysis. Fractographic analysis was performed using a light microscope and an SEM.

RESULTS

After aging, Weibull analysis revealed significantly lower bond strengths for both as-sintered and plasma-treated zirconia without a primer treatment. The fractographic analysis showed that these two conditions resulted in a higher frequency of adhesive failure.

CONCLUSION

Chemical pre-treatment with an MDP-containing primer improved bonding efficacy of 4-META/MMA-TBB resin to highly translucent zirconia. In addition, Al2O3 sandblasting resulted in durable bonding of 4-META/MMA-TBB resin to highly translucent zirconia, regardless of chemical pre-treatment.

Effects of Liner-Bonding of Implant-Supported Glass-Ceramic Crown to Zirconia Abutment on Bond Strength and Fracture Resistance

This study was conducted to test the hypothesis that heat-bonding with a liner positively affects the bond strength and fracture resistance of an implant-supported glass-ceramic crown bonded to a zirconia abutment produced by a computer-aided design/computer-aided milling (CAD/CAM) procedure. Lithium disilicate-reinforced Amber Mill-Q glass ceramic blocks were bonded to 3 mol% yttria stabilized tetragonal zirconia polycrystal (3Y-TZP) blocks by heat-bonding with a liner or cementation with a dual-cure self-adhesive resin cement for a microtensile bond strength test. CAD/CAM implant-supported glass ceramic crowns were produced using Amber Mill-Q blocks and bonded to a milled 3Y-TZP zirconia abutments by heat-bonding or cementation for a fracture test. A statistical analysis was conducted to investigate the significant differences between the experimental results. The mode of failure was analyzed using high-resolution field emission scanning electron microscopy. Chemical bonding was identified at the interface between the zirconia ceramic and liner. The mean tensile bond strength of the liner-bonded group was significantly higher than that of the cement-bonded group. The initial chipping strength of the liner-bonded group was significantly higher than that of the cement-bonded group, although no statistically significant difference was found for the fracture strength. The mode of failure was mixed with cohesive fracture through the liner, whereas the cement-bonded group demonstrated adhesive failure at the interface of bonding.

Effect of elapsed time after air abrasion on bond strength of luting agent to CAD/CAM resin blocks

This experiment assessed the effect of elapsed time between air abrasion and bonding on tensile bond strength (TBS) between computer-aided design/computer-aided manufacturing (CAD/CAM) composite resin blocks and luting agents. Specimens were divided into eight groups classified by block type (Estelite Block or HC Block), elapsed time after air abrasion (none [D0] or 1 week [D7]), luting agent type (Estecem [ESC] or Rely X Ultimate [RLU]), and polymerization condition (chemical cured [CC] or light cured [LC]). In the CC+ESC group, TBS was significantly higher at D0 than at D7. There was also a significant difference between blocks in all groups except the LC+ESC group. Scanning electron microscopy and atomic force microscopy were used to observe the surfaces of blocks after air abrasion and indicated that blocks absorbed water in air with elapsed time, which affected TBS between CAD/CAM composite resin blocks and luting agents.

A Comparative Study of Laser Irradiation Versus Sandblasting in Improving the Bond Strength of Titanium Abutments

Objective: The purpose of this study was to evaluate the effects of Er,Cr:YSGG laser irradiation with different energy powers versus sandblasting for enhancing the tensile bond strength (TBS) between titanium implant abutments (IAs) and resin cements. Background data: Clinical decementation of prosthetic restorations often occurs, particularly on short IAs. Increasing the bonding area on the IA surface can enhance the function and longevity of the superstructure. Materials and methods: Fifty dental IAs were used in solid form and randomly assigned to five groups (n = 10 each) for the following different pretreatments: control group was left untreated, a laser operating at 2.78 μm wavelength with different energy powers (1, 2, and 3 W) was used for three laser groups, and 50 μm alumina particles were applied to the abutment surface for the sandblasting group. Fifty metal substructures that had an occlusal metal O-ring were cast and cemented to all abutments using dual-cure resin cement. Test specimens were then subjected to thermal cycling. TBS tests were performed with a universal testing machine. The specimens' surface topography and roughness were evaluated with scanning electron microscope, and energy dispersive spectroscopy (EDS) was used to measure the elemental profiles of each specimen. Data were analyzed using a one-way analysis of variance/Kruskal-Wallis test at a significance level of p < 0.05. Results: Surface treatments affected the surface roughness and TBS of the IA. The sandblasting group showed the highest bond strength values (510.77 ± 60.86 N) and followed by the 2 W group (279.07 ± 37.9 N). In EDS analysis, no elemental components other than titanium and oxygen were observed, except for in the sandblasting group. Conclusions: Sandblasting and 2 W laser treatment increased the surface roughness of the IA, which could contribute to the increased interfacial bond strength between the IA and resin cement.

Effect of Implant Abutment Acid Etching on the Retention of Crowns Luted with Different Cements: An In Vitro Comparative Evaluation

Background:

Air abrasion of the implant abutment surface improves the bond strength of luting agents. However, the effect of acid etching and combination of air abrasion and acid etching on the bond strength of various luting agents under masticatory load is yet to be documented.

Purpose:

The purpose of this study was to evaluate the effect of implant abutment surface modifications on the tensile bond strength (TBS) of cast metal copings (CMCs) luted with different luting agents, subjected to cyclic fatigue loads.

Materials and Methods:

A total of 150 Ni-Cr CMCs were made on commercially pure titanium (Cp-Ti) laboratory analogues. The samples were categorized into three groups based on surface modifications and five subgroups for luting agents. The CMCs were cemented to the respective surface-modified groups, stored in distilled water at 37°C for 24 hours, and then subjected to load cycling, followed by tensile loading. One-way analysis of variance (ANOVA) was used to compare the mean bond strength between luting agents.

Results:

Self-adhesive resin cement showed the highest TBS followed by resin-modified glass ionomer cement, zinc polycarboxylate, and zinc phosphate cement. Non-eugenol temporary cement showed least TBS values on all modified abutment surfaces.

Conclusion:

Air abrasion + acid etching (HY) provided the greatest TBS followed by acid-etched (AE) surface only. Air-abraded (AA) surface yielded the least TBS for luting agents.

Evaluation of the effect of dentin surface treatment by air abrasion and Er:YAG laser on the retention of metal crowns luted with glass ionomer cement in teeth with reduced crown height: An in vitro study

Aim and Objectives

The purpose of this study was to investigate the effect of dentin surface treatment with aluminum oxide air abrasion and Er:YAG laser on tensile bond strength of metal crowns. Metal crowns were luted with conventional glass ionomer cement (GIC) in the teeth with reduced crown height, where preparation geometry did not provide optimal retention form.

Materials and Methods

Forty-eight human premolars were prepared to receive metal crowns and were randomly divided into four groups for tensile bond strength testing. Group A: Untreated dentin luted with self-adhesive composite resin cement as positive control; Group B: Untreated dentin luted with GIC as negative control; Group C: Surface treatment with 50 μm aluminum oxide air abrasion and luted with GIC; Group D: Surface treatment with Er:YAG laser (λ =2.94 mm) with a total energy 84.88 J/cm² of (60 mJ/pulse, 10 Hz, 60 pulses, and 100 μs pulse width) and luted with GIC. The cemented specimens were thermocycled and later subjected to axial load in a universal testing machine at 0.5 mm/min cross-head speed for tensile testing. Scanning electron microscopic evaluation of dentin surface treatment and cement-dentin interface was also done in representative specimens.

Results

One-way analysis of variance showed statistically significant difference among/within the groups (P < 0.001). Tukey's post hoc test presented significant increased tensile bond strength of Er:YAG laser group. Air abrasion group showed no significant increase in tensile bond strength values (P = 0.033).

Conclusion

Dentin surface treatment with Er:YAG laser significantly improved the tensile bond strength of luting GIC compared to air-abraded and untreated dentin.

Effect of thermocycling on the micro-tensile bond strength between self-adhesive resin cement and nonphosphate monomer cements on zirconium-oxide ceramics

Objectives

The objective of the present study is to evaluate the bond strength of: (a) Zirconia blocks (tribochemical treatment and zirconia primer) and resin blocks bonded using self-adhesive resin cement (phosphate monomer cement). (b) Zirconia blocks and resin blocks bonded using nonphosphate monomer cement. (c) Micro-tensile bond strength of zirconia and resin blocks, bonded with self-adhesive resin cement and nonphosphate monomer cement after thermocycling.

Materials and Methods

Twenty zirconium-dioxide specimens (5 mm × 5.4 mm × 13 mm) were produced using a metal mold. Each zirconium block was duplicated in light-curing resin material specimen (5 mm × 5.4 mm × 13 mm) using a mold made of addition silicon impression material. A total of 40 specimens were made, of which 20 specimens were zirconia blocks and 20 were resin blocks, which would be bonded to each other using phosphate monomer-containing cement (Multilink [10 nos.]) and nonphosphate monomer-containing cement (RELY-X [10 nos.]). The specimens were then divided into two groups of n = 10 each. The surface of zirconium specimen of one group (Group 1) was treated with zirconia primer and bonded with phosphate monomer-containing cement, and the other groups (Group 2) were not treated with any surface conditioning and were bonded with a nonphosphate containing cement. The specimens in each group were further subdivided into two subgroups of n = 5 each as follows: Group 1-1A (subjected to thermocycling), 1B (nonthermocycled) and Group 2-2A (subjected to thermocycling), 2B (nonthermocycled). Then, they were subjected for testing of tensile bond strength under a universal testing machine.

Results

Resin cement selection seems to be a more relevant factor in the bonding of zirconia. The phosphate monomer-containing cement has the better bond strength after thermocycling compared to the nonphosphate monomer group. Thermocycling reduced the bond strength of both the groups and a significant difference was seen in the bond strength of nonphosphate monomer cement group subjected to thermocycling compared to the nonthermocycled one. Tensile bond strength values were significantly affected by the luting agent system employed and by thermal aging. Hence, for long-term durability, luting of zirconia with a phosphate monomer-containing cement after the zirconia has been surface treated is preferable as their bond strength did not show much significant difference after being subjected to thermocycling, compared to the nonthermocycled group.

Conclusion

Resin cement selection seem to be a more relevent factor in the bonding of zirconia thermocycling does affect adhesion to to zirconium oxide ceramics.

Effect of the Dentin Chelating Agents Phytic Acid and EDTA on Degree of Conversion, Microhardness, and Bond Strength of Chemical-curing Self-adhesive Cements

PURPOSE

To evaluate the effect of the chelating agents phytic acid and EDTA on the degree of conversion (DC), microhardness, and tensile bond strength (TBS) of two chemical-curing self-adhesive cements.

MATERIALS AND METHODS

A total of 110 samples were prepared, with n = 6 in the control group to measure microhardness, n = 6 for DC measurement, and n = 10 for TBS measurement. The bovine dentin specimens were divided into five groups according to treatment: group A (control group): no treatment; group B, 1% phytic acid with ultrasonic rinsing (UR); group C: 1% phytic acid without UR; group D: 18% EDTA with UR; group E: 18% EDTA without UR. A 1-mm-thick coat of self-adhesive cement, G-CEM LinkAce (GC) or RelyX Unicem 2 (3M) was placed on control and treated dentin surfaces and stored in a dark box at 37°C, 93% ± 1% ambient humidity. DC and microhardness of cement surfaces were measured after 1 hour, 1 day, 3 days, and 1 week using Fourier transform infrared spectroscopy and a Vickers microhardness tester, respectively. TBS on treated and control dentin was evaluated after 1 week of storage in the dark box. Data were analyzed using two-way ANOVA, followed by Tukey's post-hoc test, at the 0.05 level of significance.

RESULTS

DC and microhardness of both types of cement without UR were significantly lower than that of groups in which UR was performed. Neither chelating agent had a significant effect on the TBS of G-CEM. For Rely X, the phytic acid treatment with UR showed a significantly higher TBS than the control and the EDTA groups.

CONCLUSION

The chelating agents had a negative effect on DC and microhardness of the resin cements when UR was not used. Phytic acid increased the TBS of RelyX, while EDTA groups did not with either cement.

Effect of denture cleansing agents on tensile and shear bond strengths of soft liners to acrylic denture base

Background. The aim of the present study was to evaluate the effect of Corega and 2.5% sodium hypochlorite cleansing agents on the shear and tensile bond strengths of GC soft liner to denture base. Methods. A total of 144 samples (72 samples for tensile and 72 for shear bond strength evaluations) were prepared. The samples in each group were subdivided into three subgroups in terms of the cleansing agent used (2.5% sodium hypochlorite, Corega and distilled water [control group]). All the samples were stored in distilled water, during which each sample was immersed for 15 minutes daily in sodium hypochlorite or Corega solutions. After 20 days the tensile and shear bond strengths were determined using a universal testing machine. In addition, a stereomicroscope was used to evaluate fracture modes. Data were analyzed with one-way ANOVA, using SPSS 16. Results. The results of post hoc Tukey tests showed significant differences in the mean tensile and shear bond strength values between the sodium hypochlorite group with Corega and control groups (P=0.001 for comparison of tensile bond strengths between the sodium hypochlorite and control groups, and P<0.001 for the comparison of tensile bond strengths between the sodium hypochlorite and Corega groups and the shear bond strengths between the sodium hypochlorite and Corega groups, and sodium hypochlorite and control groups).The majority of failures were cohesive in the control and Corega groups and cohesive/adhesive in the sodium hypochlorite group. Conclusion. Immersion of soft liners in Corega will result in longevity of soft liners compared to immersion in sodium hypochlorite solution and sodium hypochlorite solution significantly decreased the tensile and shear bond strengths compared to the control and Corega groups.

Bonding to Different PEEK Compositions: The Impact of Dental Light Curing Units

This study investigated the impact of different light curing units (LCUs) for the polymerization of adhesive system visio.link (VL) on the tensile bond strength (TBS) of different PEEK compositions. For TBS measurements, 216 PEEK specimens with varying amounts of TiO₂ (PEEK/0%, PEEK/20%, PEEK/>30%) were embedded, polished, air abraded (Al₂O₃, 50 µm, 0.4 MPa), conditioned using VL, and polymerized using either a halogen LCU (HAL-LCU) or a LED LCU (LED-LCU) for chairside or labside application, respectively. After thermocycling (5000×, 5/55 °C), TBS was measured, and fracture types were determined. Data was analyzed using a 2-way ANOVA followed by Tukey-HSD, Kruskal-Wallis H and Mann-Whitney U tests as well as a Chi²-test and a Ciba-Geigy table (p < 0.05). Globally, the light curing units, followed by PEEK composition, was shown to have the highest impact on TBS. The HAL-LCUs, compared to the LED-LCUs, resulted in a higher TBS for all PEEK compositions-without significant differences between chairside and labside units. Regarding the different PEEK compositions, PEEK/20%, compared to PEEK/0%, resulted in a higher TBS when both, HAL-LCUs or LED-LCUs were used for labside application. In comparison with PEEK/>30%, PEEK/20% resulted in a higher TBS after using HAL-LCU for labside application. No significant differences were found between PEEK/0% and PEEK/>30%. HAL-LCU with PEEK/20% for labside application showed a higher TBS than HAL-LCU with PEEK/20% for chairside application, whereas LED-LCU with PEEK/>30% for chairside application showed a higher TBS than LED-LCU with PEEK/>30% for labside application.

Improvement in the Tensile Bond Strength between 3Y-TZP Ceramic and Enamel by Surface Treatments

This study examined the effects of 3 mol % yttria-stabilized tetragonal zirconia polycrystal (3Y-TZP) ceramic surface treatments on the tensile bond strength and surface characteristics of enamel. To measure the tensile bond strength, the 3Y-TZP and tooth specimens were manufactured in a mini-dumbbell shape and divided into four groups based on the type of 3Y-TZP surface treatment: polishing (P), 110 µm alumina sandblasting (S), 110 µm alumina sandblasting combined with selective infiltration etching (SS), and 110 µm alumina sandblasting combined with MDP (10-methacryloyloxydecyl dihydrogen phosphate)-containing silane primer (SP). After surface treatment, the surface roughness, wettability, and surface changes were examined, and the tensile bond strength was measured. The mean values (from lowest to highest) for tensile bond strength (MPa) were as follows: P, 8.94 ± 2.30; S, 21.33 ± 2.00; SS, 26.67 ± 4.76; and SP, 31.74 ± 2.66. Compared to the P group, the mean surface roughness was significantly increased, and the mean contact angle was significantly decreased, while wettability was increased in the other groups. Therefore, surface treatment with 110 µm alumina sandblasting and MDP-containing silane primer is suitable for clinical applications, as it considerably improves the bond strength between 3Y-TZP and enamel.

Repair Bond Strength of Aged Resin Composite after Different Surface and Bonding Treatments

The aim of this study was to compare the effect of different mechanical surface treatments and chemical bonding protocols on the tensile bond strength (TBS) of aged composite. Bar specimens were produced using a nanohybrid resin composite and aged in distilled water for 30 days. Different surface treatments (diamond bur, phosphoric acid, silane, and sandblasting with Al₂O₃ or CoJet Sand), as well as bonding protocols (Primer/Adhesive) were used prior to application of the repair composite. TBS of the specimens was measured and the results were analyzed using analysis of variance (ANOVA) and the Student-Newman-Keuls test (α = 0.05). Mechanically treated surfaces were characterized under SEM and by profilometry. The effect of water aging on the degree of conversion was measured by means of FTIR-ATR spectroscopy. An important increase in the degree of conversion was observed after aging. No significant differences in TBS were observed among the mechanical surface treatments, despite variations in surface roughness profiles. Phosphoric acid etching significantly improved repair bond strength values. The cohesive TBS of the material was only reached using resin bonding agents. Application of an intermediate bonding system plays a key role in achieving reliable repair bond strengths, whereas the kind of mechanical surface treatment appears to play a secondary role.

Effect of Desensitising Laser Treatment on the Bond Strength of Full Metal Crowns: An In Vitro Comparative Study

BACKGROUND

Dentinal hypersensitivity is a very common complaint of patients undergoing crown and bridge restorations on vital teeth. Of the many desensitizing agents used to counter this issue, desensitizing laser treatment is emerging as one of the most successful treatment modality. However, the dentinal changes brought about by the desensitizing laser application could affect the bond strength of luting cements.

MATERIALS AND METHODS

Freshly extracted 48 maxillary first premolars, which were intact and morphologically similar were selected for the study. The specimens were divided into two groups, an untreated the control group and a desensitizing laser-treated group, which were exposed to Erbium, Chromium: Yttrium, Selenium, Galium, Garnet laser at 0.5 W potency for 15 s. Each of the above two groups were again randomly divided into two subgroups, on to which full veneer metal crowns, which were custom fabricated were luted using glass-ionomer and resin luting cements, respectively. Tensile bond strength of the luting cements was evaluated with the help of a Universal Testing Machine. Statistical analysis of the values were done using descriptive, independent samples' test, and two-way ANOVA test.

RESULTS

The tensile bond strength of crowns luted on desensitizing laser treated specimens using self-adhesive resin cement showed a marginal increase in bond strength though it was not statistically significant.

CONCLUSION

The self-adhesive resin cements could be recommended as the luting agent of choice for desensitizing laser treated abutment teeth, as it showed better bond strength.

In vitro Comparative Evaluation of Tensile Bond Strength of 6(th), 7(th) and 8(th) Generation Dentin Bonding Agents

BACKGROUND

Newer dentin bonding agents were developed to improve the quality of composite restoration and to reduce time consumption in its application. The aim of the present study was to evaluate tensile bond strength of 6(th), 7(th) and 8(th) generation bonding agents by in vitro method.

MATERIALS AND METHODS

Selected 60 permanent teeth were assigned into 20 in each group (Group I: 6(th) generation bonding agent-Adper SE plus 3M ESPE, Group II: 7(th) generation bonding agent-G-Bond GC Corp Japan and Group III: 8(th) generation dentin adhesives-FuturaBond, DC, Voco, Germany). With high-speed diamond disc, coronal dentin was exposed, and selected dentin bonding agents were applied, followed by composite restoration. All samples were saved in saline for 24 h and tensile bond strength testing was done using a universal testing machine. The obtained data were tabulated and statistically analyzed using ANOVA test.

RESULTS

The tensile bond strength readings for 6(th) generation bonding agent was 32.2465, for 7(th) generation was 31.6734, and for 8(th)-generation dentine bonding agent was 34.74431. The highest tensile bond strength was seen in 8(th) generation bonding agent compared to 6(th) and 7(th) generation bonding agents.

CONCLUSION

From the present study it can be conclude that 8(th) generation dentine adhesive (Futura DC, Voco, Germany) resulted in highest tensile bond strength compared to 6(th) (Adper SE plus, 3M ESPE) and 7(th) generation (G-Bond) dentin bonding agents.

Effect of desensitizing treatments on bond strength of resin composites to dentin - an in vitro study

Objectives:

Hypersensitivity is a common clinical multietiological problem. Many desensitizing treatments are there to overcome hypersensitivity. The aim of this study was to evaluate the effect of different dentin-desensitizing treatments on the tensile bond strength of composite restoration.

Materials and Methods:

Twenty-four sound human molars were used. Enamel was wet abraded to expose flat dentin surfaces, polished with sandpaper. The specimens were then divided into three groups (n = 8) based on the type of dentin-desensitizing treatment given. The first group: G1 was the control group where no desensitizing agent was used. The second group: G2 was treated with desensitizing dentifrice containing a combination of potassium nitrate, triclosan, and sodium monoflorophosphate. The third group: G3 was treated with Er:YAG laser. Afterwards, the desensitized specimens were treated with one step self-etch adhesive according to manufacturer's instructions and composite microcylinders were packed. The specimens were then examined for tensile bond strength using universal tensile machine (KMI^TM ).

Results:

Statistical analysis of the data obtained revealed the mean values for the tensile bond strengths were 10.2613 MPa, 5.9400 MPa and 6.3575 MPa for groups 1, 2 and 3, respectively. These values were statistically significantly different between groups pretreated with laser or dentifrice as compared to control group.

Conclusions:

Dentifrice and Laser pre-treated dentin has lower tensile bond strength with resin composites as compared to dentin that is untreated.

Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study

BACKGROUND

The condition of the denture bearing tissues may be adversely affected by high stress concentration during function. Chairside Denture (Hard and Soft) reliners are used to distribute forces applied to soft tissues during function. Tensile and shear bond strength has been shown to be dependent on their chemical composition. A weak bond could harbor bacteria, promote staining and delamination of the lining material. To investigate tensile and shear bond strength of 4 different commercially available denture relining materials to conventional heat cured acrylic denture base resin.

MATERIALS & METHODS

4 mm sections in the middle of 160 Acrylic cylindrical specimens (20 mm x 8 mm) were removed, packed with test materials (Mollosil, G C Reline Soft, G C Reline Hard (Kooliner) and Ufi Gel Hard and polymerized. Specimens were divided into 8 groups of 20 each. Tensile and shear bond strength to the conventional heat cured acrylic denture base resin were examined by Instron Universal Tensile Testing Machine using the equation F=N/A (F-maximum force exerted on the specimen (Newton) and A-bonding area= 50.24 mm2). One-way ANOVA was used for multiple group comparisons followed by Bonferroni Test and Hsu's MCB for multiple pairwise comparisons to asses any significant differences between the groups.

RESULTS

The highest mean Tensile bond strength value was obtained for Ufi Gel Hard (6.49+0.08 MPa) and lowest for G C Reline Soft (0.52+0.01 MPa). The highest mean Shear bond strength value was obtained for Ufi Gel Hard (16.19+0.1 MPa) and lowest for Mollosil (0.59+0.05 MPa). The Benferroni test showed a significant difference in the mean tensile bond strength and the mean shear bond strength when the two denture soft liners were compared as well as when the two denture hard liners were compared. Hsu's MCB implied that Ufi gel hard is better than its other closest competitors.

CONCLUSION

The Tensile and Shear bond strength values of denture soft reliners were significantly lower than denture hard reliners. How to cite the article: Lau M, Amarnath GS, Muddugangadhar BC, Swetha MU, Das KA. Tensile and shear bond strength of hard and soft denture relining materials to the conventional heat cured acrylic denture base resin: An In-vitro study. J Int Oral Health 2014;6(2):55-61.

Comparative evaluation of tensile bond strength and microleakage of conventional glass ionomer cement, resin modified glass ionomer cement and compomer: An in vitro study

AIM

The purpose of this study was to evaluate and compare the tensile bond strength and microleakage of Fuji IX GP, Fuji II LC, and compoglass and to compare bond strength with degree of microleakage exhibited by the same materials.

MATERIALS AND METHODS

Occlusal surfaces of 96 noncarious primary teeth were ground perpendicular to long axis of the tooth. Preparations were distributed into three groups consisting of Fuji IX GP, Fuji II LC and Compoglass. Specimens were tested for tensile bond strength by mounting them on Instron Universal Testing Machine. Ninety-six primary molars were treated with Fuji IX GP, Fuji II LC, and compoglass on box-only prepared proximal surface. Samples were thermocycled, stained with dye, sectioned, and scored for microleakage under stereomicroscope. ANOVA and Bonferrani correction test were done for comparisons. Pearson Chi-square test and regression analysis were done to assess the association between the parameters.

RESULTS

Compoglass showed highest tensile strength and Fuji II LC showed least microleakage. There was a significant difference between the three groups in tensile strength and microleakage levels. The correlation between tensile strength and microleakage level in each group showed that there was a significant negative correlation only in Group 3.

CONCLUSION

Fuji II LC and compoglass can be advocated in primary teeth because of their superior physical properties when compared with Fuji IX GP.

Comparative evaluation of tensile bond strength of a polyvinyl acetate-based resilient liner following various denture base surface pre-treatment methods and immersion in artificial salivary medium: An in vitro study

BACKGROUND AND AIM

This study was formulated to evaluate and estimate the influence of various denture base resin surface pre-treatments (chemical and mechanical and combinations) upon tensile bond strength between a poly vinyl acetate-based denture liner and a denture base resin.

MATERIALS AND METHODS

A universal testing machine was used for determining the bond strength of the liner to surface pre-treated acrylic resin blocks. The data was analyzed by one-way analysis of variance and the t-test (α =.05).

RESULTS

This study infers that denture base surface pre-treatment can improve the adhesive tensile bond strength between the liner and denture base specimens. The results of this study infer that chemical, mechanical, and mechano-chemical pre-treatments will have different effects on the bond strength of the acrylic soft resilient liner to the denture base.

CONCLUSION

Among the various methods of pre-treatment of denture base resins, it was inferred that the mechano-chemical pre-treatment method with air-borne particle abrasion followed by monomer application exhibited superior bond strength than other methods with the resilient liner. Hence, this method could be effectively used to improve bond strength between liner and denture base and thus could minimize delamination of liner from the denture base during function.

An ex vivo comparative study on the retention of custom and prefabricated posts

Aim:

This study was designed to comparatively evaluate the effect of cyclic loading on the retention of custom-fabricated fiber-reinforced composite (CF-FRC), prefabricated metal, and glass fiber posts.

Materials and Methods:

Thirty mandibular first premolars decoronated at the CE junction were divided into three groups (n=10). Groups A, B, and C were restored using Para Post (Whale dent), Reforpost (Angelus), and CF-FRC post (Ribbond-THM), respectively. Five specimens from each group were subjected to cyclic loading. Tensile bond strength (TBS) was evaluated.

Results:

Pre-loading TBS values were statistically, significantly higher for all posts (P<0.05). Before and after loading, there was a significant difference between group C as compared to groups A and B.

Conclusions:

Cyclic loading reduced the retention of all posts but was comparatively lesser for the CF-FRC post. This system provides sufficient retention required for clinical success.

Comparative evaluation of bond strength of three contemporary self-etch adhesives: An ex vivo study

Aim:

This study evaluated the effect of 2-hydroxymethyl methacrylate (HEMA) and the type of solvent on the tensile bond strength of the following three self-etch adhesives: Adper easy one (HEMA-rich adhesive) which contained ethanol, G-Bond (HEMA-free adhesive) which contained acetone, and Xeno V (HEMA-free adhesive) which contained butanol as a solvent.

Material and Methods:

Intact mandibular molars were mounted in self-cured resin and the occlusal surfaces were ground with # 600 SiC paper. Adhesives were applied on the prepared dentinal surfaces and the resin composite was condensed in the split brass mold (5 × 3 mm) placed over the adhesive surface. The specimens were stored in normal saline and placed in incubator at 37°C. After 24 hours, the specimens were tested in tensile mode at a crosshead speed of 1 mm/min. Statistical analysis was done using One way ANOVA and Tukey's HSD test.

Results:

The mean bond strengths of Adper easy one, G-Bond, and Xeno V were 12.41 MPa, 10.09 MPa, and 8.67 MPa, respectively.

Conclusions:

Comparison of contemporary adhesives in this ex vivo study revealed that the ethanol-based HEMA-rich self-etch adhesive is better than HEMA-free self-etch adhesive that contained acetone and butanol as the solvents, when compared in terms of bond strength.

Comparative evaluation of the enamel bond strength of 'etch-and-rinse' and 'all-in-one' bonding agents on cut and uncut enamel surfaces

AIMS AND OBJECTIVES

To compare tensile bond strength of an 'etch-and-rinse' bonding agent (Single bond,3M ESPE, MN, USA) with an 'all-in-one' bonding agent (iBond, Heraeus Kulzer, NY, USA) on cut and uncut enamel surfaces. The null hypothesis tested is that the 'all-in-one' bonding agent matches the 'etch-and-rinse' bonding agent in terms of tensile bond strength to enamel.

MATERIALS AND METHODS

Forty extracted human mandibular teeth were used for the study. Twenty teeth with intact enamel surfaces were divided into two groups of 10 teeth each. The enamel surfaces of the 20 teeth were prepared and assigned to two more groups of 10 teeth each. One group each of intact and prepared enamel surfaces were used to bond with the 'etch-and-rinse' bonding agent [Single bond (SB), 3M ESPE, MN, USA] and the other two groups one each of intact and prepared enamel surfaces were used to bond with the 'all-in-one' bonding agent [ iBond (IB), Heraeus Kulzer, NY, USA]. The tensile bond strength was measured on the universal testing machine (Unitek, 9450 PC, FIE, INDIA) at a cross head speed of 1 mm / minute.

RESULTS

The results were statistically analyzed using a one-way ANOVA and student 't' test. The values for the 'etch-and-rinse' bonding agent SB were significantly higher for both the cut and uncut surfaces, compared to the 'all-in-one' bonding agent IB (P < 0.05). The all-in-one bonding agent resulted in a higher bond strength on the cut enamel surfaces.

CONCLUSIONS

Based on the results, it is advisable to use the 'etch-and-rinse system' in a clinical situation requiring bonding on enamel alone.

Comparative evaluation of tensile bond strengths of total-etch adhesives and self-etch adhesives with single and multiple consecutive applications: An in vitro study

Aim:

This study evaluates the effect of single and multiple consecutive applications of adhesives on the tensile bond strength. The currently available adhesives follow either the total-etch or the self-etch concept. However, in both techniques the uniformity and thickness of the adhesive layer plays a significant role in the development of a good bond.

Materials and Methods:

Sixty composite-dentin bonded specimens were prepared using a total-etch adhesive (Gluma) and another 60 using a self-etch adhesive (AdheSE). Each group was further divided into six subgroups based on the number of applications, i.e., single application and multiple (2, 3, 4, 6, and 8) applications. The tensile bond strength was tested with the Instron universal testing machine. The values were analyzed with one-way ANOVA and multiple range tests by Tukey's HSD procedure to identify those subgroups that had significantly higher bond strength.

Results:

The results indicate that with total-etch adhesive the bond strength increases significantly as the number of applications are increased from one to two or from two to three”, for self-etch adhesive the bond strength obtained with two applications is significantly higher than that with one application. However, for both adhesive systems, there was a decrease in the tensile bond strength values with further applications.

Conclusion:

We conclude that, in the clinical setting, the application of multiple coats of total etch adhesive improves bonding.

A comparative evaluation of the bonding efficacy of two-step vs all-in-one bonding agents - An in-vitro study

Aim:

Aim of this in vitro study was to compare the tensile bond strength of UniFil Bond (GC America) vs iBond (Heraeus Kulzer) in conjunction with light cure composite resin (Venus, Heraeus Kulzer).

Materials and Methods

Sixty mandibular molars were taken and divided into 3 groups which were treated with UniFil Bond, iBond and no adhesive respectively. The tensile test was performed using an Instron machine.

Results

The results showed that multibottle systems (UniFil Bond, i.e., two-step)performed 30% better as compared with single bottle systems (all-in-one, i.e., one-step bonding agents).

Conclusion:

It can be concluded that UniFil Bond (Multibottle system – 6^thgeneration type I) performed better than iBond (Single Bottle system – 7th generation.