Bond Strength Of Resin Research Articles

Evaluation of microleakage and push-out bond strength of various composite resins for sealing the screw-access channel in implant-supported restorations

Statement of problemMicroleakage and loss of the composite resin sealing the screw-access channel are frequent complications of screw-retained implant-supported prostheses. How the screw-access channel should be best restored to reduce such complications is unclear. PurposeThe purpose of this in vitro study was to evaluate the microleakage and bond strength of 3 types of composite resins (flowable, packable, and bulk-fill) with or without a bonding agent treatment to seal the screw-access channel of 2 types of restorative materials (zirconia and Co-Cr alloy) with or without thermocycling. Material and methodsIn total, 240 yttria-stabilized tetragonal zirconia polycrystal (Y-TZP) specimens (IPS e.max ZirCAD) and 240 Co-Cr alloy (Vera PDS) specimens were prepared with a Ø3×3-mm cylindrical cavity at the center to simulate the screw-access channel. Three types of composite resins (flowable, packable, and bulk-fill resin) (Filtek Z350 XT Flowable Restorative, Filtek Z350 XT Universal Restorative, and Filtek One Bulk Fill Restorative) were applied to restore the access channel of the zirconia and Co-Cr specimens with or without a bonding agent (Single Bond Universal Adhesive). Microleakage and push-out bond strength were determined and compared by dividing the specimens into experimental groups with or without thermocycling (1000 times with 30 seconds at 5 ±2 °C and 55 ±2 °C). The results were analyzed by using a 1-way ANOVA and 4-way ANOVA. Adjustment for multiple comparisons was made with the Tukey Honestly Significant Difference (HSD) test. ResultsThe specimens subjected to thermocycling showed a lower bond strength (P<.001) and higher microleakage (P<.001) than specimens stored in a constant-temperature water bath. Specimens treated with bonding agents showed a higher bond strength (P<.001) and lower microleakage (P<.001) than specimens not treated with a bonding agent. Higher bond strengths were observed in the order of bulk-fill resin, packable resin, and flowable resin (P<.001). Packable resin showed higher microleakage than flowable resin and bulk-fill resin (P<.05). No significant difference in microleakage was found between the flowable resin and bulk-fill resin (P>.05). ConclusionsHigher bond strengths were observed in the order of bulk-fill resin, packable resin, and flowable resin. Less microleakage was observed in the flowable resin and bulk-fill resin than in the packable composite resin. Bonding agent treatment was effective in increasing bond strength and decreasing microleakage. Zirconia and Co-Cr showed a bond strength similar to that of composite resins, but zirconia showed higher microleakage than Co-Cr. Restoring the screw-access channel with the bulk-fill resin should increase bond strength and reduce microleakage.

Influence of atmospheric pressure changes on dentin bond strength of conventional, bulk-fill and single-shade resin composites.

The purpose of this study was to investigate the dentin bond strength of composite resins in response to environmental pressure changes. Ninety extracted human molar teeth were used. A mould (3 mm x 4 mm) was adapted on dentin, resin composites (conventional [n = 30] and single-shade composites [Ohmnicroma] [n = 30]) were filled in two increments of 2 mm. The bulk-fill composites (n = 30) were filled with one 4 mm increment. The specimens were stored for 30 days in artificial saliva. The specimens were exposed to hyperbaric pressure (283.6 kPa; 2.8 atmospheres absolute [atm abs]) or hypobaric pressure (34.4 kPa; 0.34 atm abs) once daily for 30 days and the control group was stored at atmospheric pressure for 30 days. The bond strength was tested with a universal testing machine and the failures were examined with a stereomicroscope and scanning electron microscope. Statistical analyses were performed using analysis of variance with post hoc tests, and the Weibull analysis. Regardless of environmental pressure changes, the bulk-fill composites showed the highest bond strength. There was no significant difference in bond strength between the hypobaric and atmospheric pressure (control) groups after 30 days in all resins. The hyperbaric group showed lower bond strength for bulk-fill composites than the control group. Dentists experienced in diving and aviation medicine should definitely take part in the initial and periodic medical examinations of divers and aircrew to give appropriate treatment. Bulk-fill composite resins can be preferred in divers and aircrew due to high bond strength values.

Comparative evaluation of the postbleaching application of sodium ascorbate, alpha-tocopherol, and quercetin on shear bond strength of composite resin to enamel.

This study aimed to evaluate and compare the impacts of the postbleaching application of sodium ascorbate, alpha-tocopherol, and quercetin on the shear bond strength (SBS) of composite resin. 60 extracted intact maxillary first premolars were collected and were randomly divided into five experimental groups as follows (n=12): Group A (negative control): no bleaching, Group B (positive control): bleaching with 40% hydrogen peroxide (HP), Group C: HP±10% sodium ascorbate for 10min, Group D: HP±10% alpha-tocopherol for 10min, and Group E: HP±1% quercetin for 10min. Composite bonding was done immediately after bleaching for Groups B-E and without any treatment for Group A. After being stored in distilled water at room temperature for 24h, all specimens were tested for SBS in the universal testing machine. One-way analysis of variance and Tukey's post-hoc test were used to analyze the SBS values of all groups. The results showed that the bonding of composite to the unbleached group exhibited the highest mean value of SBS (22.68±2.91MPa). Among the antioxidant-treated groups, the highest SBS value was detected in quercetin-treated specimens (15.45±1.58MPa), which was significantly different from the positive control group (p<.05). It could be concluded that 10% quercetin applied for 10min increased the bond strength to bleached enamel, but it was not able to reverse it completely.

Evaluation of the effect of two different desensitizing agents on shear bond strength of universal adhesive resin (an invitro study )

Evaluation of the effect of two different desensitizing agents on shear bond strength of universal adhesive resin (an invitro study )

Effect of Hydroxyapatite Synthesized from Tilapia Fish Scale Waste on the Shear Bond Strength of GIC and RMGIC to Enamel Layer (&lt;i&gt;In Vitro&lt;/i&gt; Study)

Indonesia is a country that has many types of freshwater fish, one of which is tilapia. The consumption of tilapia among the people of Indonesia is quite high. So that, it will produce a lot of fish scale waste. Fish scales can be used as a natural source of hydroxyapatite because they contain calcium. The aim of this study was to evaluate the effect of hydroxyapatite synthesized from tilapia fish scale (Oreochromis niloticus) on the shear bond strength of glass ionomer cement and resin modified glass ionomer cement to enamel layer. Hydroxyapatite was synthesized from tilapia fish scale (Oreochromis niloticus) by calcination method at 800°C. Sample was made from glass ionomer cement (GIC) and resin modified glass ionomer cement (RMGIC) combined with 2, 5 and 8%wt of hydroxyapatite, respectively. Sample was bonded to enamel layer of human premolar tooth. The shear bond strength of sample was tested by using Universal Testing Machine. The result showed that shear bond strength were increased for higher concentration of hydroxyapatite that added to glass ionomer cement or resin modified glass ionomer cement. The maximum of shear bond strength of GIC Group is 6,38 ± 0,05MPa after 8%wt hydroxyapatite addition. The maximum of shear bond strength of RMGIC Group is 6,59 ± 0,06 MPa after 8%wt hydroxyapatite addition. There were significance differences among all group tested (p &lt;0.05). It can be concluded that hydroxyapatite synthesized from tylapia fish scale can increase the shear bond strength of glass ionomer cement and resin modified glass ionomer cement.

The difference in tensile bond strength of an adhesive cement resin to an etched and perforated resin-bonded bridges

Several improvements to the metal cast framework have been suggested since resin-bonded fixed partial dentures was introdu-ced. Essentially, there are twotypes of retainer designs based on retention namely macromechanical retention with a perforated retainer commonly referred to as Rochette bridge and micromechanical retention derived from the etched metal cast retainer called as Maryland bridge. This study is aimed to compare the tensile bond strength of anadhesive cement resin to an etch and perforated resin-bonded bridge. Using experimental laboratory design, the sample tested consisted of 10 plates Ni-Cr alloy,13 mm in diameter and 1 mm in thickness were divided into two treatment groups; five plates were perforated, and five plates were etched using Met-Etch Gel. Tensile strength was determined using an Ametek Llyod Instrument. The result showed that the strength of resin adhesive cement on the metal surface of alloyNi-Cr used etch higher than perforated. Statistical analysis used student t-test recorded t-test 2.75 and p-value 0.0125, so it said significant differences becausep-value was smaller than 0.05. This study showed that etch cast metal retainers were more retentive than perforated design.

Effect of Er:YAG, Co2 lasers, papain, and bromelain enzymes dentin treatment on shear bond strength of composite resin.

Effective bond strength of composite resin restoration leads to its durability, so evaluation of dentin surface treatment with enzymes and laser for higher bond strength is an important factor. Sixty human molar teeth were cut at a depth of 2 mm of occlusal part and divided into sixgroups (n = 10). G1: etched with 37% phosphoric, G2 and G3: 10% papain or bromelain enzymes were used on the dentinal surface, G4: 10% papain and bromelain enzyme mixture were used for. Then, the specimens were washed with distilled water. In G5 and G6: Er:YAG or Co2 lasers were used on the dentin surface. An adhesive system was applied and then nanohybrid composite was placed in teflon mold and lightcured. Samples were subjected to a shear bond strength (SBS) testby universal testing machines. Statistical analysis was performed, using one-way analysis of varianceand Tukey HSD tests (p < .05). The mean SBS in G1 was significantly higher in comparison with the other groups (p < .0001). On the other hand, a comparison of mean SBS between groups 2, 3, 4, and 5 shows no significant differences (p = .221). The mean SBS in group 6 (Co2 laser) was significantly lower in comparison with the other groups (p < .0001). Results showed that SBS of composite resin to dentin was not significantly affected, using either bromelain or papain 10% enzymes or erbium laser. Co2 laser had a negative effect on dentin and decreased the SBS. Phosphoric acid has the best result.

Effect of heating antioxidants and delayed bonding on bond strength to bleached enamel

Objective: The aim of this study was to evaluate the influence of heating natural antioxidants on their antioxidant activity and on micro shear bond strength of composite resin to bleached enamel. Materials and methods. A hundred-eighty flowable composite cylindrical specimens of 0.8 mm diameter and 1 mm length were bonded to enamel substrate for microshear bond strength evaluation. Six study groups were created (n=30). Group 1: No bleaching, Group 2: Bleaching only, Group 3: Bleaching+ Pine Bark Extract at Room temperature, Group 4: Bleaching + Pine Bark Extract preheated to 60° C. Group 5: Bleaching+ Grape Seed Extract at Room temperature, Group 6: Bleaching+ Grape Seed Extract preheated to 60° C. All groups were tested immediately (subgroup a), after one week (subgroup b) and two weeks (subgroup c). Both extracts were tested for their antioxidant activity using DPPH assay at room temperature, 40° and 60°. Two- and one- way ANOVA were used to explore the effect of different surface treatments and bonding time on microshear bond strength. Results. DPPH results showed the heated antioxidant extracts to have significantly higher antioxidant activity than their non-heated counterparts.

Disinfection of caries-affected dentin using potassium titanyl phosphate laser, Rose bengal and Ozonated water on shear bond strength of deciduous teeth

AimTo assess the efficacy of disinfection of caries-effected dentin (CAD) using KTP laser and different decontamination methods using ozonated water (OW), Rose Bengal photosensitizer (RBP), chlorhexidine (CHX), and Er, YAG laser on the shear bond strength (SBS) of adhesive resin bonded to deciduous teeth. Material and methodsA total of 50 extracted and radiographically verified carious primary molars were collected and scrutinized according to ICDAS criteria. Specimens were allocated randomly into five groups (n = 10) as per the type of CAD disinfectants. KTP laser, OW, RBP, CHX (control), and Er, YAG laser. After cavity sanitization, a resin adhesive (prime and bond NT) was smeared on the dentinal exterior followed by incremental composite filling. SBS evaluation was performed by employing specimens in the universal testing machine. The debonded surface was assessed under 40x magnification in a stereomicroscope to ascertain fracture mode. Statistical analysis was done by using the ANOVA and the Post Hoc Tukey multiple comparison tests (p < 0.05). ResultsThe highest SBS was exhibited by group 2 i.e., when OW was employed for CAD disinfection (10.25 ± 0.24 MPa). Whereas, the lowest SBS bond value was unveiled by samples in group 3 when RBP was applied for dentin surface sanitization (7.85 ± 0.59 MPa).CAD disinfection with KTP laser (8.25 ± 0.41 MPa), CHX (8.19 ± 0.73 MPa), and RBP displayed comparable bond values (p > 0.05). ConclusionOzonated water and Er, YAG laser could be employed as cavity disinfectants in primary teeth as they demonstrated better shear bond strength without jeopardizing the adhesive binding capacity of restorative resins bonded to caries-affected dentin.

Comparative Evaluation of Push-Out Bond Strength &amp; Adaptation of A Fiber Post Cemented with Biodentine, MTA &amp; Resin Cement: An in Vitro Study.

Aim of our study is to evaluate &amp; compare the push-out bond strength and adaptation of a fiber post cemented with Biodentine, MTA, and dual-cure Resin cement. A total of thirty mandibular premolars with a single oval root canal were prepared and obturation was done by AH plus sealer and gutta-percha. The teeth were stored at 37 0C with 100% humidity for one day. The gutta-percha was removed by peeso reamer, leaving at least 4 mm of filling material, and post spaces were prepared by corresponding fiber post drill. The specimens were randomly distributed into (n=10) among each 3 groups. Glass fiber Posts were lutted with three different materials and coronally sealed with glass ionomer cement followed by stored in water for 24 h at 37 0 C. Each tooth was sectioned into 3 parts of 2-mm-thick slices in coronal, middle and apical zone. Push-out bond strength was measured with help of a universal testing machine and evaluated the adaptation by scanning electron microscope after 7 and 28 days. Statistical analysis was done by one-way anova and post hoc test. The push-out bond strength of dual-cure resin and Biodentine was non-significant but higher in comparison to Pro Root MTA. Dual cure resin cement and Biodentine also showed better surface adaptation to post in comparison to MTA. This present study showed that Biodentine can also be used for luting the fiber post as an alternative to dual-cure resin cement.

Surface Treatments on Repair Bond Strength of Aged Resin Composites.

ABSTRACTAims:The aim was to evaluate the effect of different surface treatments on the repair shear bond strength of aged resin composites.Materials and Methods:Forty cylindrical-shaped specimens were treated from each material: Tetric Evo Ceram, Neo Spectra, and Filtek Ultimate Universal Restorative and allocated into four groups according to the surface treatment planned to use: Group 1: diamond, Group 2: silica coating, Group 3: carbide burs, and Group 4: control group. Following the surface treatment, composites were repaired with flowable resins. The shear bond strength was tested using a universal testing machine at a crosshead speed of 0.5 mm/min. The fracture mode was assessed under 50× magnification. The data were analyzed statistically using a two-way analysis of variance (ANOVA) test followed by a one-way ANOVA test. Multiple comparison procedures were performed using Tukey’s test. The level of significance was set at P < 0.05.Results:The lowest mean value of the shear bond strength was for the Filtek Ultimate Universal Restorative in the control group, whereas the highest mean value was in the silica group. Silica and carbide groups had significantly higher mean values of the shear bond strength than diamond and control groups in Tetric EvoCeram and Filtek Ultimate Universal Restorative. In contrast, in Neo Spectra St HV, the carbide group had a higher mean value but was not statistically significant.Conclusion:Combinations of mechanical and chemical retentive systems enhance the shear bond strength of the repair composite to the aged composite. Among the different surface treatments employed in this study, silica and carbide groups show higher repair bond strength of new composite to aged composite.

Evaluation of shear bond strength of resin adhesive/tooth interface after modification with grape seed extract: An in-vitro study

Evaluation of shear bond strength of resin adhesive/tooth interface after modification with grape seed extract: An in-vitro study

Influence of Human and Bacterial Enzymes on Resin Restorations: A Review

Esthetic satisfaction has been a prime concern for patients. This has led to a surge in the development of esthetic restorations and dental composites in the field of restorative dentistry over the past decade. Resins are the most preferred restorative material. However, their failure rate was observed to be high. This review is aimed for clinician, discussing the influence of human and bacterial enzymes on resin restorations. Composite restoration failure is multifactorial with an interplay of mechanical functions such as masticatory forces and abrasion with biological factors such as host modulated and bacterial enzymes. Salivary esterases and bacterial esterases act on the ester-link bond of resin restoration to form byproducts of methacrylic acid and Bis-hydroxy-propoxy-phenyl-propane. Salivary enzymes form microgaps between the resin-tooth interface and provide a suitable environment for bacterial growth. Bacteria colonize the resin-tooth interface to weaken the resin bond strength. The presence of bacteria draws neutrophils into the hybrid layer. The activation and degranulation of neutrophils leads to enzyme secretions that act on bacteria. However, this can also have adverse effects on resin restoration. Acids prompt the activation of matrix metalloproteinases (MMPs). Proteinases secreted by MMPs uncoil the collagen fibrils of the dentin matrix and degrade tooth structure. The salivary esterases, bacterial esterases, neutrophils, and MMPs work synergistically to degrade dental resin material, resin-tooth interface, and dentin. This causes failure of dental resin restorations and secondary caries formation. Biological degradation of resin restorations is inevitable irrespective of the material and techniques used. Salivary esterases such as cholesterol esterase and pseudocholinesterase and cariogenic bacterial esterase can degrade dental resin, weakening the hybrid layer at the resin-tooth interface, affecting the bond strength, and causing failure. Ester-free resin and incorporation of antimicrobial materials, esterase, and MMP inhibitors are strategies that could ameliorate degradation of the restoration.

Effect of airborne particle abrasion and primer application on the surface wettability and bond strength of resin cements to translucent zirconia

The purpose of this study was to evaluate the effect of sandblasting and primer application on the immediate and long-term shear bond strength of resin cements to translucent zirconia. Zirconia plates (Katana STML, Kuraray Noritake Dental) were divided into six groups (n = 10) for shear bond strength evaluation using three resin cements (Panavia V5, Kuraray Noritake Dental; Variolink Esthetic LC, Ivoclar-Vivadent; and Panavia SA Cement Universal, Kuraray Noritake Dental). The zirconia was sandblasted or left unabraded. Each cement was used with the indicated primer. Two cylinders of cement were placed on the zirconia, one for evaluation after 24 h and the other after 1 year of storage in water. The fracture pattern and the contact angle were observed on all groups. At 24 h, there were no differences in bond strength of the cements for equal sandblasting conditions. After 1-year, the bond strength of all groups decreased, except for Panavia V5 associated with sandblasting. For all the cements, the unabraded zirconia showed a lower bond strength and a higher rate of adhesive failures. The application of primers reduced the contact angle. Higher bond strength is obtained when primers are combined with sandblasting using aluminum oxide particles. Clinical significance: Translucent zirconia restorations should be treated by airborne particle abrasion and phosphate-based primers before bonding, to improve the wettability of the cements and obtain a more durable bonding between the cement and the zirconia.

Bond Strength of CAD/CAM Ceramic by Various Modern Resin Cements in Multilayer Technique

BACKGROUND&#x0D; The purpose of the study was to assess bond strength of various modern resin cements based on CAD-CAM ceramic in multilayer technique.&#x0D; METHODS&#x0D; CAD-CAM blocks specimens, IPS e.max ZirCAD (core, n=60) and IPS e max CAD (veneer, n=60) were fabricated. All specimens were divided into 3 groups (n=20). By multilayer technique, zirconia core and veneer were cemented with 3 different cements, RelyX U200 (MR), Panavia V5 (MP), and Multilink N (MM]. Ageing was performed for (5-55°C, 5000). The shear bond strength test was performed with a universal test unit. The data were analyzed using the analysis of variance (ANOVA) and Tukey significant difference test (alpha =0.05).&#x0D; RESULTS&#x0D; The SBS differed substantially depending on the resin cement used. Group MP had the highest bond strength (P &lt; .001) and lower MM. No significant differences were found between the groups MR and MM.&#x0D; CONCLUSIONS&#x0D; Significant differences were found in the shear bond strength of the veneer luted to zirconia base in multilayer technique using self-adhesive and conventional cement. The bond strength depended on the combination of ceramic and cement. The Panavia V5 had the highest bond strength.

Mechanical Properties of SDR™ and Biodentine™ as Dentin Replacement Materials: An In Vitro Study

The aim of this study is to evaluate the shear bond strength of nanohybrid composite resins (NCR) and microhybrid composite resins (MCR) placed over three different dentin replacement materials: SDR-Smart Dentin Replacement™, Biodentine™, and resin-modified glass ionomer cement (RMGIC). Thirty acrylic blocks (50 mm × 20 mm × 15 mm), each with a central hole, were prepared, which were randomly distributed into three equal groups, each corresponding to one of the three dentin replacement materials-SDR, Biodentine, and RMGIC. The central holes were then filled with these materials. After setting and application of the respective adhesive system, the specimens were further divided into two subgroups each of NCR or MCR. The respective composite material was then applied to the dentin replacement materials using a cylindrical plastic matrix. Shear bond strength was tested on a universal testing machine (Instron 3366), at a crosshead speed of 1.0 mm/minute. SDR attained consistently higher shear bond strength (means: 21.18, 22.19 Mpa) values than RMGIC and Biodentine, with both types of composite resins (MCR and NCR), which were statistically significant (p <0.001). When considering the means of the shear bond strength measurements obtained by the two types of the composite resin, no significant difference (p <0.05) was found between them with all three types of dentin replacement materials. There is no significant difference in the bond strengths achieved between MCR and NCR to the different dentine replacement materials. Hence, either type of composite resin may be expected to achieve similar bond strengths to the underlying substrate. SDR™ is a suitable dentine replacement material for placing below a composite resin veneer as it can achieve immediate higher bond strengths. SDR can be used as an effective bulk fill material in deep dentinal caries which can be capped with composite resins.

Repairability of aged dimethacrylate-free ORMOCER-based dental composite resins with different surface roughening methods and intermediate materials

Statement of problemThe repair of damaged composite resin restorations has been recommended as a conservative treatment option. However, a reliable protocol for repairing ORMOCER-based restorations is lacking. PurposeThe purpose of this in vitro study was to investigate the effect of different surface roughening methods, repair composite resins, and intermediate materials on the repair bond strength of a dimethacrylate-free ORMOCER-based composite resin. Material and methodsCylindrical composite resin specimens (Admira Fusion) were roughened by using hydrofluoric acid (HF) or a diamond rotary instrument. In both groups, 4 types of intermediate materials were used (Monobond-S, Clearfil SE bond [second bottle], Clearfil Universal bond, GC Composite Primer), and then half of the specimens were repaired with a similar composite resin, and the other half with dimethacrylate composite resin (Clearfil-APX). The specimens (n=20) were then subjected to repair bond strength and failure mode evaluation. The data were analyzed by using the Weibull test, 3-way and 1-way ANOVA, and the Tukey honestly significant difference (HSD) test (α=.05). ResultsAll variables, including the surface roughening method, intermediate material, and repair composite resin, had a significant effect on repair bond strength (P<.001). The lowest repair bond strength values were obtained in the group roughened with HF, prepared with Monobond-S, and repaired with Admira Fusion, and the highest values were obtained in the group roughened with a rotary instrument, prepared with GC Composite Primer, and repaired with Clearfil APX (P<.05). All experimental groups had a lower bond strength than the cohesive and control groups (P<.05). In all experimental groups, the predominant failure modes were adhesive and mixed. ConclusionsThe use of a diamond rotary instrument was a more reliable method of creating roughness, and different intermediate materials based on the clinical situation can be used to repair dimethacrylate-free ORMOCER-based composite resin with similar or different composite resins. However, in general, the highest repair bond strengths were achieved with Clearfil APX-repaired specimens.

Effect of Different Universal Bonding Agent Procedures on Repair of Feldspathic and Hybrid Ceramics.

To perform application of universal bonding agent based only on the manufacturer's instructions for CAD/CAM-manufactured feldspathic and hybrid ceramics and to investigate the bond strength of the composite resin to these ceramics. A total of 120 samples (2-mm thickness) were obtained from three different CAD/CAM-manufactured ceramics each: a feldspathic ceramic (Vitablocs Mark II), a hybrid ceramic (Cerasmart, GC), and a dual-network ceramic (Vita Enamic). Each of these restorative materials was divided into six subgroups (n = 20 each) in order to apply universal adhesives: All-Bond Universal, Clearfil Quick Universal, Premio Bond, Optibond XTR, Prime&Bond, and Tokuyama Universal Bond. Each bonding agent was applied according to the manufacturer's instructions. Microshear bond strength test was performed at a crosshead speed of 1 mm/min. Two-way analysis of variance (ANOVA) and Tukey post hoc tests were used for statistical analyses. The data suggested a significant impact of bonding agent on all restorative materials applied (P < .001); however, only Prime&Bond demonstrated different effects between materials, with a significant difference between Vitablocs Mark II and Cerasmart restorative materials (P = .001). All universal bonding agents provided an acceptable bond strength for each ceramic. Since different universal bonding agents affected the bond strength between ceramics and composite resin, selecting the most suitable bonding agent for each material will increase the bond strength and clinical success.

Adhesion to a Zirconia-reinforced Lithium Silicate Ceramic: Effects of Ceramic Surface Treatments and Resin Cements

This study had the objective to test the effect of ceramic surface treatments on the microshear bond strength (μSBS) of different resin cements to a zirconia-reinforced lithium silicate (ZLS). ZLS blocks were sectioned, embedded in acrylic resin, and then allocated into nine groups considering two study factors: "ceramic surface treatment" (HF - hydrofluoric acid; EP - self-etching primer; TBS - tribochemical silica coating) and "resin cements" (nMDP - without MDP monomer; MDP - with MDP monomer; SA - self-adhesive). Starch tubes (n=36) were placed on the treated ceramic surface and the cement was applied. Starch tubes were removed after 24 hours of storage, and the specimens were thermocycled (5,000×; 5°C-55°C). Next, the μSBS test was performed using the wire-loop technique, and topographic and failure analyses were performed. The factors "ceramic surface treatment" and "resin cement" statistically influenced the μSBS results. Considering the surface treatment factor, the TBS produced statistically lower values when the MDP resin cement was applied, being only similar to the MDP plus EP group. For the resin cement factor, no difference was found for nMDP and SA groups, apart from the surface treatments. Failure analysis showed that the groups treated with EP had a greater number of pre-test failures. The surface treatments induced noteworthy topographic alterations when compared to control (no treatment). The ZLS ceramic surface treatment with tribochemical silica coating associated with the MDP-containing resin cement resulted in lower bond strength values.

Influence of ceramic veneer on the transdentinal cytotoxicity, degree of conversion and bond strength of light-cured resin cements to dentin

ObjectivesTo investigate the transdentinal cytotoxicity (TC), degree of conversion (DC), and micro shear bond strength (μSBS) to dentin of light-cured resin cements (LCRCs) photoactivated directly or through a ceramic veneer( ± CV). Materials and methodsThe TC was assessed using human dentin discs adapted into artificial pulp chambers. Odontoblast-like cells were seeded on the pulp surface of the discs, then three LCRCs( ± CV) were applied on their etched and hybridized occlusal surface (n = 8/group). The adhesive systems of each LCRCs and sterile phosphate-buffered saline were used as positive and negative controls, respectively. After 24 h, the viability and morphology of cells adhered on discs were assessed. The extracts (culture medium + components of the materials diffused through the discs) were applied on the MDPC-23 to evaluate their viability, adhesion/spreading (A/S), alkaline phosphatase activity (ALP), and mineralized nodule formation (MN). LCRCs( ± CV) specimens were evaluated concerning the DC and μSBS to dentin. Data were analyzed by one-, two-, or three-way ANOVA/Dunnett, Sidak, and Games-Howell tests (α = 5%). ResultsAll LCRCs( ± CV) reduced cell viability, A/S, ALP, MN, and DC. Except for μSBS, the intensity of reduction was dependent on the LCRC used. LCRCs+CV resulted in lower DC and μSBS but did not increase the TC. SignificanceBesides the presence of CV between the light source and LCRCs reduces the degree of conversion and bond strength to dentin, these materials cause variable level of transdentinal toxicity to pulp cells. Thus, the composition and curing protocols of LCRCs should be revisited and reinforced to prevent mechanical and biological drawbacks.