Bifix QM Research Articles

Effect of CAD-CAM block thickness and translucency on the polymerization of luting materials

AimThis in-vitro study aimed to evaluate the degree of conversion (DC) of dual-cured luting cement (Bifix QM, VOCO) and flowable composite (Grandio Flow, VOCO) under lithium disilicate glass-ceramic (IPS e.max CAD, Ivoclar Vivadent) and hybrid ceramic (Grandio Blocs, VOCO; Cerasmart, GC) CAD-CAM blocks with different thicknesses.Materials and methodsContrast ratio (CR), translucency (TPab, TP00), and opalescence (OP) parameters of 30 disc-shaped CAD-CAM blocks (n = 5) prepared with two different thicknesses (1.5 and 2 mm) and 8 mm diameters were calculated using a spectrophotometer (VITA Easyshade V, Zahnfabrik). A total of 36 Bifix QM and Grandio Flow samples were prepared at 100 μm thickness using a specific setup by polymerizing from the top of the blocks. Following immersion in distilled water at 37 °C for 24 h, luting materials were examined by Fourier Transform Infrared Spectroscopy for DC calculation. Data were analyzed using One-way ANOVA, Kruskal Wallis, Mann Whitney U, and Independent Samples t-tests (p < 0.05).ResultsIt was observed that, as the block thickness increased TPab, TP00, and OP decreased, while CR increased. There was no significant difference between the DC of Bifix QM and Grandio Flow when 1.5 mm blocks were used in all groups (p > 0.05). DC of Grandio Flow was significantly higher than Bifix QM under 2 mm-IPS e.max CAD (p = 0.011).ConclusionThe translucency of the CAD-CAM blocks varies depending on their thickness. However, there was no significant difference in the DC of the luting materials depending on the block thickness. Further studies are needed on the use of flowable resin composites as luting material.

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

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

Is there a correlation between physical properties and film thickness of dual- and photo-polymerized resin cements and CAD/CAM-dentin micro-tensile bond strength?

To correlate µTBS of different resin cements with their film thickness (FT), Vickers hardness (HV), and ultimate tensile strength (UTS). Human molars (N = 30) were divided into six-groups according to 1: Resin cement: Bifix QM, (BF), GrandioSo Heavy Flow (GHF) and VisCalor Bulk (VB), and 2: Adhesive mode (Optibond Universal): Etch-and-rinse (E&R) or self-etching (SE). CAD/CAM blocks (7 × 7 × 4 mm3) were air-abraded using 50 μm Al2O3 and silane was applied (60 s), and air dried (10 s). For E&R, dentin was etched (15 s), rinsed (30 s), and blot-dried. For both modes, adhesive was applied (20 s), air-dried (5 s), and photo-polymerized (10 s). Sticks (1 × 1 mm2) were stored for 24-h or 6-months. Sticks were pulled in tension (1 mm/min). Debonded sticks were evaluated for failure mode analysis. For FT, nine-bonded slabs from each cement was prepared and evaluated. For UTS, eight-hourglass specimens from each cement were prepared and tested in tension. For HV, five-discs from each cement was prepared and evaluated using a HV tester. Data were analyzed using ANOVA/Pearson’s correlation tests (α = 0.05). No correlation between µTBS/HV was revealed (p > 0.05). A positive correlation between µTBS/FT and µTBS/UTS (p < 0.05) was observed. Three-way ANOVA revealed all experimental factors had a significant effect on µTBS (p < 0.05). The VB showed significantly lower µTBS (20.8 ± 9.3 MPa). The E&R mode showed higher µTBS (26.0 ± 10.9 MPa), and 24-h revealed a higher µTBS (27.4 ± 10.0 MPa). Mixed failure was the predominant type (42.51%). The VB showed the highest FT (122.2 ± 11.9 µm), with GHF revealed higher UTS and HV (112.5 ± 19.7 MPa and 91.6 ± 0.4 Kgf, respectively). Photo-polymerized flowable composite can substitute dual-polymerized cement for CAD/CAM composite bonding.

Fracture strength of endocrowns after thermomechanical aging.

This in-vitro study aimed to evaluate the fracture strength (FS; N) of composite, feldspathic, and glass-ceramic computer-aided design/computer-aided manufacturing (CAD/CAM) endocrowns after thermomechanical aging. Seventy non-carious human molars were randomly divided into seven groups, according to the CAD/CAM material used for endocrown fabrication. Intact molars without cavity preparations were used as control (n = 10). Following endodontic treatment, standardized endocrown cavities were prepared and endocrowns were fabricated using composite (Cerasmart270, CS and Grandio Blocs, GB), fired and milled zirconia-reinforced lithium silicate (Celtra Duo, CD), leucite-reinforced feldspar ceramic (LRF Initial, LRF), and feldspathic (Cerec Blocks, CE) materials which were luted with universal adhesive (Futurabond U; Voco) and dual-cure resin cement (Bifix QM). Following thermocycling for 20,000 cycles and 480,000 load cycles in a chewing simulator (CS-4.2, SD Mechatronik), FS was evaluated (Instron). Data were analyzed with one-way ANOVA and post hoc Tukey's tests (p < 0.05). FS was significantly influenced by the tested material (p = 0.00). CS had the highest FS, which was not significantly different from intact molars and fired CD (p > 0.05). There were no significant differences in FS between LRF, GB, and CD, which were significantly higher than CE. Most of the failure modes of CS, CD, and GB were repairable, whereas those of CE were irreparable. All the tested materials withstood clinically relevant axial forces. Composite endocrowns exhibited more favorable fracture pattern, whereas feldspathic and leucite-reinforced feldspar ceramic endocrowns exhibited mostly irreparable fractures.

Shear Bond Strength Assessment of Vita Suprinity Ceramic to Enamel and Dentine Using Three Different Resin Cements

Purpose: The current study aimed to asses shear bond strength of Vita Suprinity ceramics bonded to dentine and enamel utilizing three different types of resin cements. Materials and Methods: Sixty ceramic samples (Vita Suprinity) were divided according to the tooth substrate into two equal groups (thirty samples cemented to enamel substrate and thirty samples to dentine substrate). Each group was divided into three subgroups (n=10) according to cementation mechanism: SubgroupI; Etch r Self etch mechanism (Bifix QM resin cement and futura bond) and subgroupIII; Self- adhesive mechanism (Relyx Unicem). The cemented specimens were thermocycled then shear bond strength was measured. Results: By comparing cementation protocols the total etch mechanism recorded the highest bond strength while the self- adhesive mechanism recorded the lowest strength. Comparing substrates, the enamel results were significantly higher than that of dentine results. Conclusion: Although the self etch and self-adhesive resin cements are simple in manipulation, their bond strength is lower than that of total etch technique so they need improvement.

Bond Strength Stability of Different Dual-Curing Adhesive Cements towards CAD-CAM Resin Nanoceramic: An In Vitro Study

Background: To evaluate different adhesive luting procedures on coronal dentin bond-strength of Cerasmart CAD-CAM blocks with μTBS test. Methods: 36 molar crowns were flattened in order to expose sound dentin and a standardized smear layer was created with 600 grit paper. Specimens were divided into six groups according to the luting cement employed (n = 12 each): G1: Panavia V5 (Kuraray, Japan); G2: Bifix QM (Voco, Germany); G3: Estecem (Tokuyama, Japan). CAD-CAM blocks (Cerasmart, GC), shade A2LT, size 14, were sectioned with a diamond saw to obtain 4 mm high specimens, which were then luted on the coronal dentin, following the manufacturer instructions. Specimens were serially sectioned to obtain 1 mm thick beams in accordance with the μTBS test technique. Half of the beams were stressed to failure after 24 h (t = 0), while the other half were stored in artificial saliva for 12 months, at 37 °C, for ageing before stressing to failure (t = 12). Results: two-way ANOVA test showed significant difference for the factor “luting cement” (p = 0.0002), while the factor “time of storage” (p = 0.0991) had no significant effect on µTBS. Conclusions: PanaviaV5 seems to have better µTBS values at T0 than QM and ES and 1 year aging doesn’t seem to affect the bonding strength of tested systems.

Marginal microleakage of flowable resin composites used to adhere Semi-Direct restorations

Introduction Conservative Dentistry has gradually replaced traditional invasive procedures with minimally invasive techniques that rely on adhesion to tooth substrates [1]. Due to these recent developments, indirect restorations are increasingly used in contemporary practice. In order to bond these restorations, a vast choice of materials exist, and these include flowable resin composites [2,3]. However, studies featuring these materials are seldom found [3]. The aim of this in vitro pilot study was to evaluate and compare the microleakage of indirect restorations luted with a flowable composite and different luting agents. Materials and methods This study was approved by the Ethics Committee of Egas Moniz, CRL. Thirty human molars were randomly divided between 3 groups (n = 10) according to the luting agent used: resin cement Bifix QM (VOCO GmbH, Cuxhaven, Germany) (G1), pre-heated resin composite Z100 MP Restorative (3 M ESPE) (G2) and flowable composite GrandioSO Flow (VOCO GmbH, Cuxhaven, Germany) (G3). Standardised class V cavities were prepared in the buccal surface and immediate dentine sealing was carried out with Optibond FL (Kerr). Composite restorations were made using a semi-direct technique with GrandioSO (VOCO GmbH, Cuxhaven, Germany). After 24 h cavities and restorations were pre-treated and adhesively luted according to the groups. After finishing and polishing, specimens were stored in distilled water at 37 °C for 24 h. After thermal aging (500 cycles at 5–55 °C) teeth were sealed and immersed in 0.5% basic fuchsine dye for 4 h. Each specimen was then sectioned vertically and microleakage was assessed and classified for both occlusal and cervical margins according to ISO/TS 11405:2015. The results were statistically analysed by Kruskal–Wallis (KW) test and binomial data analysis, at a significance level of 5% (SPSS 24.0). Results There were no significant differences in microleakage scores between the tested groups (p > .05, KW). All the groups scored more leakage in cervical margins. Binomial analysis confirmed that the success rate was material and margin dependent. The probability of failure of a cervical margin bonded to Z100 (G2) and to GrandioSO Flow (G3) using a semi-direct technique was significantly higher than 50% (p = .021) and (p = .002) respectively. Z100 had 100% failure rate in the cervical margin. Discussion and conclusions Longevity of a bonded interface is determined by sealing and microleakage. When this interface is compromised, failure of the restoration may happen [4]. Microleakage occurred in composite restorations made semi-directly the same way amongst the different materials used for bonding. However, cervical margins bonded with resin composites carry a greater chance of failure.

The effect of silane and universal adhesives on the micro-shear bond strength of current resin-matrix ceramics.

PURPOSEThe aim of this in vitro study was to evaluate the effect of silane and universal adhesive applications on the micro-shear bond strength (µSBS) of different resin-matrix ceramics (RMCs).MATERIALS AND METHODSA total of 120 slides (14 × 12 × 1 mm) were produced from 5 different RMC materials (GC Cerasmart [GC]; Brilliant Crios [BC]; Grandio blocs [GB]; Katana Avencia [KA]; and KZR-CAD HR 2 [KZR]) and sandblasted using 50 µm Al2O3 particles. Each RMC material was divided into six groups according to the surface conditioning (SC) method as follows: control (G1), silane primer (G2), silane-free universal adhesive (G3), silane-containing universal adhesive (G4), silane primer and silane-free universal adhesive (G5), and silane primer and silane-containing universal adhesive (G6). Three cylindric specimens made from resin cement (Bifix QM) were polymerized over the treated surface of each slide (n = 12). After thermal cycling (10000 cycles, 5 – 55℃), µSBS test was performed and failure types were evaluated using a stereomicroscope. Data were analyzed using 2-way ANOVA and Tukey tests (α = .05).RESULTSµSBS values of specimens were significantly affected by the RMC type and SC protocols (P < .001) except the interaction (P = .119). Except for G2, all SC protocols showed a significant increase in µSBS values (P < .05). For all RMCs, the highest µSBS values were obtained in G4 and G6 groups.CONCLUSIONOnly silane application did not affect the µSBS values regardless of the RMC type. Moreover, the application of a separate silane in addition to the universal adhesives did not improve the µSBS values. Silane-containing universal adhesive was found to be the best conditioning method for RMCs.

The Effect of Aging and Surface treatments on Micro-shear Bond Strength of Resin Nano-Ceramic Material Using Two Resin Cements

Purpose: To evaluate the effect of aging and different surface treatments on micro-shear bond strength of two resin cements to resin nano-ceramic composite blocks using an in-vitro study. Materials and methods: Blocks of resin nano-ceramic (Lava Ultimate, 3M, St Paul, Minnesota, USA) were used to prepare eight plates having the following dimensions: (14mm × 12mm × 2mm). After plates preparation they were assigned to two main groups according to the surface treatment applied, either hydrofluoric acid etching and silane or sandblasting and silane. Scanning electron microscope (SEM) was used to analyze the surface topography of the Lava-Ultimate plates before and after application of surface treatments. Two resin cements were used; dual cured adhesive resin cement (Bifix QM, VOCO, Cuxhafen, Germany) and dual cured self-adhesive resin cement (Bifix SE, VOCO, Cuxhafen, Germany) to create a five resin micro-cylinders received on each lava ultimate plate. Ten specimens from each subgroup were tested after 24 hours and the other ten specimens were tested after aging in saline for 6 months. Micro-shear bond strength test was applied until failure. . Multi-factorial ANOVA test and One-way ANOVA followed by pair-wise Tukey’s post-hoc tests were used to analyze the data. Results: Both resin cements showed statistically significant decrease on bond strength after aging. Before aging, both surface treatments with adhesive resin cement showed statistically significant higher micro-shear bond strength mean values than with self-adhesive resin cement. After aging sandblasting showed a statistically significant higher micro-shear bond strength mean values with adhesive resin cement, while hydrofluoric acid etching revealed a statistically non-significant higher values with adhesive resin cement than self-adhesive resin cement. Conclusion: For both surface treatments and resin cements aging had a detrimental effect on micro- shear bond strength.

Effect of Surface Treatment and Aging on Bond Strength of Composite Cement to Novel CAD/CAM Nanohybrid Composite.

To evaluate the effect of surface treatments and aging on the bond strength of composite cement to a novel CAD/CAM nanohybrid composite. Microtensile bond strength (µTBS) of a dual-curing composite cement (Bifix QM; BQ) to three CAD/CAM restorative materials (Grandio [GR], Vita Enamic [VE], and Lava Ultimate [LU]) was evaluated after different surface treatments. The surfaces of specimens received the following treatments: control (no treatment), sandblasting (SB), SB + silane (Ceramic Bond; CB), hydrofluoric acid (HF), HF + CB, TiF4 2 wt/v%, TiF4 2 wt/v% + CB, TiF4 4 wt/v%, and TiF4 4 wt/v% + CB. Half of the specimens in each group were aged. Surface topography and surface roughness were evaluated. Statistical analysis was conducted using ANOVA and Tukey's test. The Weibull analysis was conducted on µTBS data of aged groups. The µTBS was significantly affected by the type of CAD/CAM material, type of treatment, and aging (p < 0.001). Silane application significantly improved the µTBS (p < 0.05). The µTBS decreased significantly with aging (5000 thermocycles) (p < 0.05). BQ cement resulted in the highest μTBS to GR treated with TiF4 2% wt/v + CB compared to the other groups (p < 0.05). Aged GR/BQ treated with TiF4 2% wt/v + CB had the highest predicted µTBS (19 MPa). TiF4 2% wt/v followed by silane application enhanced the adhesion of GR/BQ and LU/BQ systems. On the other hand, HF surface treatment followed by silane application improved the adhesion of the VE/BQ system.

An investigation of atomic force microscopy, surface topography and adhesion of luting cements to zirconia: effect of silica coating, zirconia primer and laser

This study evaluated the effect various surface conditioning methods on the surface topography and adhesion of luting cements to zirconia. Zirconia blocks (N = 25) were randomly assigned to five groups according to the surface conditioning methods: (a) No conditioning, control (CON), (b) tribochemical silica coating (TSC), (c) MDP-based zirconia primer (ZRP), (d) coating with nano aluminum nitride (ALN) (e) etching with Er: YAG laser (LAS). The conditioned zirconia blocks were further divided into five subgroups to receive the luting cements: (a) MDP-based resin cement (Panavia F2.0) (PAN), (b) 4-META-based cement (Super Bond) (SUB), (c) UDMA-based (GCem) (GCE), (d) bis-GMA based (Bifix QM) (BIF) and (e) polycarboxylate cement (Poly-F) (POL). Cements were applied in polyethylene moulds (diameter: 3 mm; height: 2 mm). The bonded specimens were first thermocycled for 5500 cycles (5–55 °C) and then adhesive interface was loaded under shear (0.5 mm/min). The data (MPa) were analyzed using 2-way ANOVA, Tukey’s and Bonneferroni tests (alpha = 0.05). Regardless of the cement type, TSC resulted in significantly higher bond strength (p ˂ 0.05) (13.3 ± 4.35–25.3 ± 6.3) compared to other conditioning methods (2.96 ± 1.5–5.4 ± 5.47). Regardless of the surface conditioning method, no significant difference was found between MDP, 4-META and UDMA based cements (p > 0.05) being significantly higher than those of bis-GMA and polycarboxylate cements (p ˂ 0.05). Failure types were frequently adhesive in all groups. Tribochemical silica coating provided superior bond results compared to other conditioning methods tested on zirconia especially in conjunction with UDMA- and 4-META-based resin cements.

Effect of Silica Coating with Different Luting Cements on the Bond Strength of a Zirconia Based Ceramic

Statement of the problem: Debonding is a common cause of failure in zirconia-basedrestorations. Despite the use of resin cements and surface treatments, the rate of success remainsto be questioned.Purpose: The purpose of this study was to evaluate the effect of surface treatment using asilica coating (Co-Jet) method with different luting cements on the shear bond strength to zirconiasamples. The hypothesis was that surface treatment with different luting cements will influence thebond strength at the ceramic-cement interface.Materials and Methods: In this study 30 zirconia samples were constructed and underwentsurface treatment using a silica coating method (Co-Jet system). Zirconia samples were then bondedto composite samples using different luting agents (Bifix QM, Panavia 2.0 and Multilink Automix).Samples underwent a thermocycling aging process before shear bond strength was tested.Results: The highest shear bond strength was recorded with the Panavia 2.0 group while thelowest was with the Bifix QM group.Conclusions: Within the limitations of this study, the use of a Co-Jet sand silica coating systemwith Panavia 2.0 showed superior bond strength than the other luting cements.

Influence of nonthermal argon plasma on the shear bond strength between zirconia and different adhesives and luting composites after artificial aging.

PURPOSEPlasma activation of hydrophobic zirconia surfaces might be suitable to improve the bond strength of luting materials. The aim of this study was to analyze the influence of nonthermal argon-plasma on the shear bond strength (SBS) between zirconia and different combinations of 10-MDP adhesive systems and luting composites after artificial aging.MATERIALS AND METHODSTwo hundred forty Y-TZP specimens were ground automatically with 165 µm grit and water cooling. Half of the specimens received surface activation with nonthermal argon-plasma. The specimens were evenly distributed into three groups according to the adhesive systems ([Futurabond U, Futurabond M, Futurabond M + DCA], VOCO GmbH, Germany, Cuxhaven) and into further two subgroups according to the luting materials ([Bifix SE, Bifix QM], VOCO GmbH). Each specimen underwent artificial aging by thermocycling and water storage. SBS was measured in a universal testing machine. Statistical analysis was performed using ANOVA and Scheffè procedure with the level of significance set to 0.05.RESULTSSurface activation with nonthermal plasma did not improve the bond strength between zirconia and the tested combinations of adhesive systems and luting materials. The plasma-activation trended to reveal higher bond strength if the self-etch luting material (Bifix SE) was used, irrespective of the adhesive system.CONCLUSIONPlasma-activation seems to be suitable to improve bond strength between zirconia and self-etch resin materials. However, further research is necessary to identify the influence of varying plasma-parameters.

Effect of saliva contamination and artificial aging on different primer/cement systems bonded to zirconia

Statement of problemSaliva contamination has been shown to decrease bonding to zirconia. Adopting a less contamination-sensitive cement system may be an alternative to decontamination. PurposeThe purpose of this in vitro study was to assess the ability of different primer/cement systems to promote a durable bond to zirconia after saliva contamination. Material and methodsZirconia blocks (Lava Plus) (N=320) were airborne-particle abraded (50 μm Al2O3) and divided into 32 experimental groups (n=10) according to the variables in the study: saliva contamination; primer/cement system (Panavia SA [PSA]; RelyX Unicem 2 [RU2]; Bifix SE [BSE]; Panavia F2.0 [PF2]; Scotchbond Universal + RelyX Ultimate [SBU+RXU]; Futurabond M+ + Bifix QM [FBM+BQM]; All-Bond Universal + Duo-link [ABU+DL]; Z-Prime Plus + Duo-link [ZPP+DL]; and aging period (72 hours; 30 days with 10 000 thermocycles at 5°C to 55°C). After half of the blocks had been contaminated with fresh human saliva for 10 minutes, rinsed with water, and air-dried, each primer/cement was applied. Polymerized composite resin disks were then placed over the cement, and the resin cement was light-polymerized for 20 seconds each at 2 opposite margins. After the aging time, the specimens were tested in shear (1 mm/min). The failure mode was classified as adhesive, cohesive, or mixed. Statistical analysis of the shear bond strength (SBS) data was performed with ANOVA followed by Tukey honest significant difference post hoc tests. Chi-square tests were used to analyze the failure mode data (α=.05). ResultsThe mean SBS ranged between 4.2 and 34.5 MPa. Shear bond strength was influenced (P<.001) by all the factors studied (cement system, saliva contamination, aging time). SBU+RXU and FBM+BQM showed a higher mean SBS than those of the other experimental groups (P<.05) and were the only groups not affected by saliva contamination (P>.05). Failure was predominantly classified as adhesive. ConclusionsIn general, saliva contamination and aging decreased bonding efficacy. Two systems, combining an application of a universal adhesive and a resin cement (SBU+RXU and FBM+BQM) were not affected by saliva contamination.

Efficacy of Different Surface Treatments for Intraoral Repair of Veneered Zirconia Frameworks.

To evaluate the efficacy of different surface treatments on the repair of veneered zirconia ceramics. Forty-eight zirconia disks were divided into three groups according to the method of surface treatment: polished surface, air abraded, or ground using a special silicon carbide bur (SiC Grinding Bur). All specimens were primed using a primer containing MDP (Cimara Zircon, Voco) and then bonded to composite in Plexiglas tubes using dual-curing adhesive resin (Bifix QM, Voco). Each of the three groups was further divided into two subgroups (n = 8) stored either in water at 37°C for 3 days without thermocycling or stored in water at 37°C for 150 days with an additional 37,500 thermocycles between 5°C and 55°C. After storage, tensile bond strength (TBS) was measured in a universal testing machine. After 3 days of storage, silicon carbide bur and air-abraded groups showed high TBS that ranged from 32.7 to 41.0 MPa (p ≤ 0.05). After 150 days of storage with thermocycling, the air-abraded group showed the most durable TBS (34.8 MPa), while the silicon carbide bur group showed a significant reduction in TBS (21.2 MPa); in the polished control group, specimens all debonded spontaneously during storage (p ≤ 0.05). Repair of zirconia ceramic after chipping of its veneers showed durable TBS when surface conditioning with air abrasion or roughening of the zirconia surface with a silicon carbide bur was provided.

Microtensile Bond Strength of Three Restorative Core Materials with IPS e.max Press Ceramic by Two Resin Cements

Objectives: The aim of this study was to compare the microtensile bond strengths (µ TBS) of three core materials with one lithium disilicate reinforced ceramic using two resin cements.Methods: Three core materials (Nulite F® (Biodental Technologies), Filtek Z250® (3M-ESPE), Prettau-Anterior® (Zirkonzhan, Germany)) were prepared as blocks (10×10×4 mm3) according to the manufacturer’s instructions. Lithium disilicate ceramic blocks were also constructed and bonded to core specimens with two dual curing luting resin cements (Duo-Link® (Schaumburg, IL), Bifix QM® (VOCO, Cuxhaven, Germany)). Micro-bar specimens were prepared and loaded in tension to determine the µ TBS Failure modes were classified by scanning electron microscope (SEM). Data were analysed using two-way ANOVA and Tukey HSD test.Results: The µ TBS varied significantly depending on the core materials and resin cements used (P 0.05). The highest bond strength was obtained between zirconia core and Bifix QM (45.3 ± 6.7 MPa).Conclusion: In vitro µ TBS of glass ceramic blocks bonded to zirconia core material showed higher bond strength values than resin-based core material, regardless of the resin cement type used.

Bond Strength of Zirconia to Different Core Materials

ABSTRACT Background Since bonding to zirconia is still questionable, the aim of this study was to evaluate the bond strength of yttrium-stabilized tetragonal zirconia polycrystal (Y-TZP) to different materials used to manufacture dental cores, employing a universal self-etching adhesive system. Materials and methods Cylinders obtained from blocks of Y-TZP Zirconia were sintered in a high-temperature oven. The surfaces to be bonded were blasted with aluminum oxide, then silica-coated aluminum oxide, and finally cleaned in ultrasonic bath. The specimens were divided into six groups according to the core material tested: Silver alloy (Ag/Sn/Cu, Tecnofix), copper alloy (Cu/Ni/Zn, Goldent LA), core buildup resin (Rebilda DC — VOCO), Y-TZP zirconia (IPS e.max ZirCAD, Ivoclar Vivandent), enamel, and dentin. The zirconia cylinders were bonded to the core substrates using the Futurabond U adhesive system (VOCO) and resinous cement (Bifix QM — VOCO). The specimens were shear tested in a universal testing machine at 1 mm/ min. Data was analyzed using ANOVA and Tukey's test. Results Bond strength in MPa (±SD) for the different materials tested were dentin: (12.80 ± 3.18)a; enamel: (15.13 ± 3.09) ab; resin: (17.20 ± 4.67)ab; copper alloy: (18.93 ± 4.66)bc; silver alloy: (22.86 ± 5.47)c; and zirconia: (23.65 ± 3.64)c. Groups followed by the same letters are not significantly different at p &lt; 0.05. Conclusion The metallic alloys and zirconia core materials showed significantly higher bond strength than those obtained directly on dentin. The core buildup resin bond strength to zirconia is similar to that obtained with enamel and dentin. How to cite this article Frattes FC, de Oliveira JBS, Pucci CR, Borges AB, Torres CRG. Bond Strength of Zirconia to Different Core Materials. World J Dent 2016;7(4):169-174.

FRACTURE STRENGTH AND MICROLEAKAGE OF SIMULATED IMMATURE TEETH REINFORCED WITH FIBER POST: IN VITRO STUDY

Aim of the study: This in vitro study was conducted to investigate the fracture strength and microleakage of simulated immature teeth reinforced with fiber post using two types of composite resin cement “ total etch and self etch “. Materials and methods: Eighty freshly extracted maxillary central incisors were used in the study, they were divided into two groups (40 samples for each) according to the stage of root development (mature – immature), Then each group was subdivided into two subgroups (20 samples for each) according to the type of adhesive composite resin cement (RELY X TM U200 Automix) (3M ESPE Germany) self-adhesive and (Bifix QM) ( Voco. GERMANY) total etch , Each subgroup was further divided into two classes (10 samples for each) according to subjecting the samples to thermocycling or not , Finally 5 samples from each class were tested for fracture strength by using universal testing machine and the other 5 samples of each class were tested for microleakage by using digital microscope. Results: The results of the fracture strength test showed that mature teeth showed higher fracture strength than simulated immature teeth. Total etch composite resin composite cement showed higher fracture strength than self etch cement. Finally the results showed that thermocycling affects negatively on fracture strength. As regard microleakage, the reults pointed out that no microleakage occurred in all tested groups. Conclusions: Fracture strength of mature teeth is more than immature teeth, using total etch composite resin cement give more fracture strength than self etch composite resin cement, thermocycling affects negatively the fracture strength for mature or immature endodontically treated teeth, no microleakage occurred irrespective to the state of restored root (mature or immature).

Cytotoxicity evaluation of luting resin cements on bovine dental pulp-derived cells (bDPCs) by real-time cell analysis.

To evaluate the cytotoxicity of resin cements on dental pulp-derived cells (bDPCs), Bifix QM (BQM), Choice 2(C2), RelyX U200(RU200), Maxcem Elite(ME), and Multilink Automix(MA) were tested. The materials were incubated in DMEM for 72 h. A real-time cell analyzer was used to evaluate cell survival. The statistical analyses used were one-way ANOVA and Tukey-Kramer tests. BQM, RU200, and ME demonstrated a significant decrease in the bDPCs' index at 24 and 72 h (p≤0.001). These materials were found to be the most toxic resin cements, as compared to the control and other tested materials (C2 and MA). However, C2 and MA showed a better survival rate, compared to BQM, RU200, and ME, and had lower cell index than the control group. The cytotoxic effects of resin cements on pulpa should be evaluated during the selection of proper cements.

Comparison of Different Dentin Pretreatment Protocols on the Bond Strength of Glass Fiber Post Using Self-etching Adhesive

IntroductionThis study compared the influence of different irrigants with and without ultrasound or laser irradiation on the bond strength of glass fiber posts using a self-etching adhesive in a supplementary dentin pretreatment. MethodsNinety bovine incisor roots were divided into 3 groups according to the irrigant tested: 2% chlorhexidine (CHX) (n = 30); 2.5% sodium hypochlorite (NaOCl) (n = 30), and saline solution (control) (n = 30). Each group was randomly divided into 3 subgroups according to the supplementary dentin pretreatment: ultrasound, Nd:YAG laser, and nonsupplemented (control). A self-etching adhesive system (Futurabond DC; VOCO GmbH, Cuxhaven, Germany) was used, and the glass fiber posts were cemented with dual-cure epoxy-based luting agent (Bifix QM, VOCO GmbH). All roots were sectioned transversely, and the push-out test was performed. Failure mode analysis was also evaluated. ResultsBond strength decreased significantly after the use of 2.5% NaOCl in all root thirds (P < .05). CHX showed no difference in the mean bond strength value compared with saline solution (P > .05). The supplementary dentin pretreatment using the Nd:YAG laser or ultrasound did not improve the bond strength values for both NaOCl and CHX (P > .05). Moreover, the apical third exhibited the lowest mean bond strength values (P < .05). Analysis indicated that the predominant failure mode was the mixed type. ConclusionsRegardless of the irrigant used, the supplementary dentin pretreatment with ultrasound or laser irradiation showed no improvement in bond strength. Also, the use of NaOCl decreased the bond strength of glass fiber posts using a self-etching adhesive system, whereas CHX preserved it.