Microtensile bond strength of CAD/CAM materials to dentin under different adhesive strategies

Comparison of the shear bond strengths of two different polyetheretherketone (PEEK) framework materials and CAD-CAM veneer materials

BACKGROUND

This study evaluated the shear bond strength (SBS) of two different polyetheretherketone (PEEK) and CAD-CAM materials after aging.

METHODS

A total of 42 frameworks were designed and milled from 2 different PEEK discs (Copra Peek, P and BioHPP, B). P and B frameworks were divided into 3 subgroups (n = 7). 14 slices were prepared each from feldspathic ceramic (Vitablocs Mark II, VM), hybrid nanoceramic (Cerasmart, CS), and polymer-infiltrated ceramic (Vita Enamic, VE) blocks. After surface preparations, the slices were cemented to P and B surfaces. The samples were subjected to thermal aging (5000 cycles). SBS of all the samples was measured. Fractured surfaces were examined by SEM/EDX analysis. The Shapiro-Wilk, Two-way Robust ANOVA and Bonferroni correction tests were used to analyze the data (a = .05).

RESULTS

Frameworks, ceramics, and frameworks x ceramics had significant differences (p < 0.05). The highest SBS value was seen in B-VM (p < 0.05). VM offered the highest SBS with both P and B. The differences between P-VM, P-CS, P-VE and B-CS and B-VE were insignificant (p > 0.05). According to EDX analysis, ytterbium and fluorine was seen in B content, unlike P. While VM and CS contained fluorine, barium, and aluminum; sodium and aluminum were observed in the VE structure.

CONCLUSION

Bonding of P and B with VM offers higher SBS. VM, CS and VE did not make any difference in SBS for P, however VM showed a significant difference for B.

Effect of thermocycling on the mechanical properties of permanent composite-based CAD-CAM restorative materials produced by additive and subtractive manufacturing techniques

BACKGROUND

The aim of the study was to determine and compare the biaxial flexural strength (BFS) and Vickers hardness (VHN) of additive and subtractive manufactured permanent composite-based restorative materials, before and after thermal aging.

METHODS

A total of 200 specimens were prepared; 100 disc-shaped specimens (diameter 13 × 1.2 mm) for the BFS test and 100 square specimens (14 × 14 × 2 mm) for the VHN test. The specimens were made from various materials: two subtractive composite-based blocks (Cerasmart 270 [CS], Vita Enamic [VE]), two additive composite-based resins used for two different vat polymerization methods (digital light processing [DLP]; Saremco Print Crowntec [SC] and stereolithography [SLA]; Formlabs Permanent Crown Resin [FP]), and one feldspathic glass-matrix ceramic block (Vita Mark II [VM]) as the control group. Specimens of each material were divided into two subgroups: thermal cycled or non-thermal cycled (n = 10). BFS and VHN tests were performed on all groups. Data were analyzed with two-way ANOVA and post hoc Tukey test (α = 0.05).

RESULTS

The type of restorative material used for the specimen had a statistically significant influence on both BFS and VHN values. However, thermal cycling did not affect the BFS and VHN values. After thermal cycling, the results of the BFS test were ranked from best to worst as follows: CS, FP, SC, VE, then VM. For the VHN values, the order from best to worst was as follows: VM, VE, CS, FP, then SC.

CONCLUSIONS

3D printed and milled composite groups showed higher BFS than feldspathic ceramics. When the VHN results were examined, it was seen that the 3D resin groups had the lowest VHN values. Furthermore, it was observed that the thermal cycle had no effect on BFS or VHN.

In vitro assessment of the effect of luting agents, abutment height, and fatigue on the retention of zirconia crowns luted to titanium base implant abutments

STATEMENT OF PROBLEM

The bonding of implant-supported prostheses is determined by abutment material, convergence angle, height, surface treatment, and luting agents. However, studies evaluating the bonding of luting agents to titanium base abutments with different heights under fatigue conditions are scarce.

PURPOSE

The purpose of this in vitro study was to evaluate the retention of zirconia crowns bonded with different luting agents to titanium base abutments of different heights before and after fatigue testing.

MATERIAL AND METHODS

Zirconia crowns were designed, milled, and distributed into 4 experimental groups according to the luting agents (G-Multi Primer/G-Cem LinkForce [MP/GC] and Scotchbond Universal/RelyX Ultimate [SU/RU]) and titanium base abutment heights (2.5 mm and 4 mm) (n=10). Pull-out testing was performed in a universal testing machine at a crosshead speed of 1 mm/min until crown displacement. Fatigue testing was performed by an electric precision fatigue simulator (1×106 cycles; 100 N; and 15 Hz), followed by pull-out testing of fatigued specimens. Collected data were statistically evaluated by using a linear mixed model after post hoc comparisons by the least significant difference test (α=.05).

RESULTS

Luting agents, abutment heights, and fatigue influenced the bonding retention of zirconia crowns to titanium base abutments. SU/RU agents promoted higher pull-out compared with MP/GC for both abutment heights before and after fatigue. Higher abutment height increased pull-out regarding lower abutment height for SU/RU materials before and after fatigue testing. Although fatigue had no significant effect on the pull-out of MP/GC, lower bond retention was observed for SU/RU after fatigue, regardless of abutment height.

CONCLUSIONS

Luting agent composition and the interaction with abutment height and fatigue influenced the retention of zirconia crowns to titanium base abutments.

Fracture resistance of CAD/CAM blocks cemented on dentin using different cementation strategies

PURPOSE

To determine whether the fracture resistance of computer-aided design/computer-aided manufacturing (CAD/CAM) resin-based composites and polymer-infiltrated ceramic network materials cemented on dentin is influenced by the restoration thickness and composite cement application strategy.

METHODS

Disc-shaped specimens (Ø = 7 mm) of 0.8 mm and 1.5 mm thicknesses were milled from two CAD/CAM materials: resin-based composite (RBC, Cerasmart 270) and polymer-infiltrated ceramic network (PICN, Vita Enamic). The discs (n = 8 per group) were cemented on flattened dentin using three different cementation strategies: 1) self-adhesive composite cement (RelyX U200) in light-curing mode (LC-SAC), 2) universal adhesive (Single Bond Universal) with composite cement (RelyX Ultimate) in auto-curing mode (AC cement), and 3) adhesive and composite cement as in 2) but in light-curing mode (LC cement). The restorative surface was indented perpendicularly with a compressive load using a universal testing machine until fracture. The fracture resistance (N) of RBC and PICN was separately analyzed using two-way ANOVA and Tukey's post-hoc test (α = 0.05).

RESULTS

The fracture resistance of each material was significantly influenced by the material thickness and cementation strategy (P < 0.05). Irrespective of the material type and cementation strategy, thicker materials exhibit higher fracture resistance. For RBC, the fracture resistance of the LC cement group was significantly higher than that of AC cement only at 0.8 mm thickness. For PICN, the LC-cement cementation strategy produced superior fracture resistance, regardless of the restoration thickness.

CONCLUSIONS

The fracture resistance of Cerasmart 270 was higher for the thicker material; the fracture resistance of LC cement was higher than that of AC cement at 0.8 mm thickness cemented to dentin. In comparison, LC cement showed the highest fracture resistance for Vita Enamic for both material thicknesses.

HASTABAŞI CAD-CAM BLOKLARIN EROZE DENTİNE MAKASLAMA BAĞLANMA DAYANIMI

Amaç: Bu çalışmada hastabaşı bilgisayar destekli tasarım-bilgisayar destekli üretim (CAD-CAM) bloklarının self-etch ve self-adeziv rezin simanlar kullanılarak gastrik erozyona uğratılmış dentine olan makaslama bağlanma dayanımlarının değerlendirilmesi amaçlanmıştır. Gereç ve Yöntemler: Yüz seksen dentin örneği sağlam dentin ve eroze dentin olmak üzere iki gruba ayrılmıştır. Eroze dentin grubunda örnekler HCI (0,01 M, pH 2, 2 dk) ile erozyona uğratılmış ve 60 dk yapay tükrükte bekletilmiş, sonrasında, elektrikli diş fırçası kullanılarak (2N, 15 s) fırçalanmıştır. Bu döngü üç kere tekrar edilmiştir. Lava Ultimate (LU), Vita Enamic (VE) ve Vita Suprinity (VS) CAD-CAM blokları (3x3x3 mm3, n=15/grup) self-etch Multilink N (MN) ve self-adeziv RelyX U200 Automix (RU) rezin simanları kullanılarak sağlam ve eroze dentin örneklerine simante edilmiştir. Makaslama bağlanma dayanımı 24 saat sonra ölçülmüştür. Başarısızlık tipi stereomikroskop kullanılarak değerlendirilmiştir. Veriler üç-yönlü ANOVA ve Bonferroni düzeltmesi kullanılarak analiz edilmiştir (p˂0,05). Bulgular: Makaslama bağlanma dayanımı ana faktörlerden önemli ölçüde etkilenmiştir: diş yapısı (p=0,011), rezin simanlar (p˂0,001) ve CAD-CAM bloklar (p=0,001). LU sağlam dentine RU ile simante edildiğinde, eroze dentinle karşılaştırıldığında daha yüksek bağlanma dayanımı elde edilmiştir (p=0,001). MN kullanıldığında, RU’dan daha yüksek bağlanma dayanımı değerleri elde edilmiştir (p

Surface Treatment and Cementation of Lithium Silicate Ceramics Containing ZrO2

Objective

To evaluate the effect of different surface treatments on the shear bond strength (SBS) of lithium silicate (LS) and lithium disilicate (LD) ceramics, after thermocycling.

Methods and Materials

For SBS test, 72 ceramic blocks (18×14×2 mm) were made (24 blocks from each ceramic material): VITA Suprinity (LSS), Celtra Duo (LSC), and Lithium disilicate (LD). The blocks were polished with sandpaper of increasing grit (#280, #400, #800, and #1200) and embedded in chemically activated acrylic resin. Afterwards, they were randomly divided into 12 groups (6 blocks per group) according to: “Ceramic” (LD, LSC, and LSS) and “Surface treatment” (HFS: hydrofluoric acid + silane; MEP: Monobond Etch & Prime/Ivoclar). From each treated surface ceramic block, four dual-curing resin cement cylinders (RelyX U200, 3M Oral Care) were prepared using a Tygon tube (Ø=3 mm and h=2 mm) and light cured for 40 seconds (1000 mW/cm2) (N=288/n=24). All specimens were submitted to thermocycling (10,000 cycles, 5°C and 55°C, 30 seconds) and then to SBS test at a crosshead speed of 1 mm/min using a 50-kgf load cell. Forty-five additional blocks were made for roughness and SEM analysis. Failure mode was also performed. The data (MPa) were statistically analyzed by oneway analysis of variance (ANOVA), Tukey test (5%), and Weibull analysis. The Ra was analyzed by Kruskal–Wallis and Dunn Test (5%). The other variables were analyzed qualitatively.

Results

ANOVA revealed that “surface treatment” was significant for all ceramic materials (p&lt;0.05). The LD-HFS (18.66±3.49), LSC-HFS (16.81±2.62), and LSS-HFS (16.33±3.08) groups had significantly higher SBS than the LD-MEP (7.00±4.2), LSC-MEP (14.12±3.51), and LSS-MEP (13.87±2.52) groups. Complete adhesive failures at the cement– dentin interface were more frequent. Weibull modulus was superior for the LD-HFS (6.22), LSC-HFS (8.8), and LSS-HFS (7.4) groups.

Conclusion

HF followed by silanization is the most suitable surface treatment for the cementation of LS and LD glass ceramics.

Evaluation of Micro-Shear Bond Strength of Four Different CAD-CAM Polymer-Infiltrated Ceramic Materials after Thermocycling

PURPOSE

To evaluate the bond strength of three monolithic hybrid ceramics/resin nanoceramics and a zirconia-reinforced lithium silicate to resin cement after thermocycling.

MATERIALS AND METHODS

Using four materials, including Vita Enamic (VITA Zahnfabrik), Lava Ultimate (3M ESPE), Crystal Ultra (Digital Dental), and Vita Suprinity (VITA Zahnfabrik), 64 specimens were prepared with dimensions of 4mm×3mm×1.5mm. Vita Suprinity samples were sintered at 840°C for 8 min. After polishing and cleaning all the samples in each group (n = 16), they were subjected to their recommended surface treatment: 10% hydrofluoric acid for Vita Enamic (60s) and Vita Suprinity (20s); air abrasion of Lava Ultimate and Crystal Ultra with 50μ Al₂ O₃ particles. Then, tygon tubes were filled with dual cure resin cement (Panavia F2.0), cured and then subjected to thermal cycling (2000 cycles; 5-55°C). The micro-shear bond strength was measured using micro-tensile testing machine. The data were analyzed using Welch and Games-Howell tests (α = 0.05). The mode of failure was also evaluated using a stereomicroscope.

RESULTS

The highest and the lowest mean micro-shear bond strength belonged to the Crystal Ultra (7.71 ±1.54 MPa) and Vita Suprinity (4.73 ±1.87 MPa) groups, respectively. The differences between groups were significant and Crystal Ultra had higher bond strength in comparison to all three materials (p<.05).

CONCLUSION

Hybrid ceramics showed higher bond strength to resin cements in comparison to resin nanoceramics and zirconia-reinforced lithium silicate materials. This article is protected by copyright. All rights reserved.

Micro-shear bond strengths of resin-matrix ceramics subjected to different surface conditioning strategies with or without coupling agent application

PURPOSE

This study aimed to assess the influence of various micromechanical surface conditioning (MSC) strategies with or without coupling agent (silane) application on the micro-shear bond strength (µSBS) of resin- matrix ceramics (RMCs).

MATERIALS AND METHODS

GC Cerasmart (GC), Lava Ultimate (LU), Vita Enamic (VE), Voco Grandio (VG), and Brilliant Crios (BC) were cut into 1.0-mm-thick slices (n = 32 per RMC) and separated into four groups according to the MSC strategy applied: control-no conditioning (C), air-borne particle abrasion with aluminum oxide particles (APA), 2W- and 3W-Er,Cr:YSGG group coding is missing. The specimens in each group were further separated into silane-applied and silane-free subgroups. Each specimen received two resin cement microtubules (n = 8 per subgroup). A shear force was applied to the adhesive interface through a universal test machine and µSBS values were measured. Data were statistically analyzed by using 3-way ANOVA and Tukey HSD test. Failure patterns were scrutinized under stereomicroscope.

RESULTS

RMC material type, MSC strategy, and silanization influenced the µSBS values (P<.05). In comparison to the control group, µSBS values increased after all other MSC strategies (P<.05) while the differences among these strategies were insignificant (P>.05). For control and APA, there were insignificant differences between RMCs (P>.05). The silanization decreased µSBS values of RMCs except for VE. Considerable declines were observed in GC and BC (P<.05).

CONCLUSION

MSC strategies can enhance bond strength values at the RMC - cement interface. However, the choice of MSC strategy is dependent on RMC material type and each RMC can require a dedicated way of conditioning.

Impact of the Microstructure of CAD/CAM Blocks on the Bonding Strength and the Bonded Interface

PURPOSE

To investigate the relationship between the microstructure of CAD/CAM blocks and the quality of adhesion as function of the surface treatment and resin cement type.

MATERIALS AND METHODS

Two nano-ceramic composite resin CAD/CAM blocks, Lava Ultimate (LU) and Cerasmart (CS), and two Leucite-reinforced glass ceramic CAD/CAM IPS blocks, Empress^® CAD (EM) and Initial^TM LRF (IR), received either Hydrofluoric acid (HF) or sandblasting (SB) surface treatments. The blocks were then luted using two dual-cure resin cements, LinkForce (LF) and Multilink Automix (ML) with their corresponding silanes, resulting in 16 study groups. The luted blocks were then thermal-cycling (TC) for 5000 cycles and subjected to a microtensile bond strength (μTBS) test. Scanning electron microscopy (SEM) micrographs of the treated surfaces were analyzed using ImageJ software and XRD analyses were performed for the two ceramic blocks. The data obtained were submitted to Games-Howell post-hoc nonparametric test to compare combinations of groups or treatments and a linear mixed-effects model for the factors surface treatment, block type, and resin cement, together with their first-degree interactions (α = 0.05).

RESULTS

The lowest mean μTBS values were obtained with LU-HF, whereas the highest mean μTBS values were obtained with CS regardless of resin cement type and surface treatment method. IR-HF mean μTBS were significantly higher than IR-SB, EM-SB, and EM-HF. Analysis using ImageJ software demonstrated significant differences in the density and pore size after HF surface treatment.

CONCLUSIONS

The specific microstructure of each block material within the same family group impacted the micromechanical retention and the bonded interface strength.