The effect of elapsed time following alumina blasting on adhesion of CAD/CAM resin block to dentin

Reliability of an Innovative Slab Shear versus Microtensile Bond Strength Test: Mechanical and Finite Element Analysis

OBJECTIVE

 The aim of this study was to evaluate the efficiency of slab shear bond strength test (Slab_SBS) versus the microtensile in evaluation of the bond strength of different substrates.

MATERIALS AND METHODS

 Forty-eight extracted caries-free human third molars were utilized for teeth specimens' preparation. After flattening of all molars' occlusal table, the specimens were divided into two groups based on the type of utilized restorative material: nanohybrid resin composite and resin-modified glass ionomer (RMGI). Each group was further subdivided into three subgroups according to the subsequently applied bond strength test and specimen width; microtensile bond strength test (μTBS), Slab_SBS [2 mm] and Slab_SBS [3 mm]. Both testing methods were additionally applied on CAD/CAM specimens, nanohybrid resin composite blocks (composite-to-composite), and ceramic blocks (ceramic-to-ceramic). CAD/CAM specimens were prepared and cemented and then sectioned and subdivided as followed for teeth specimens' preparation. Pretest failures (PTF), bond strength, and failure mode of each specimen were recorded. Representative three-dimensional (3D) finite element analysis (FEA) models were developed to simulate μTBS and Slab_SBS specimens. Data were statistically analyzed using Shapiro-Wilk test and Weibull analysis.

RESULTS

 Pretest failures were only noted in the μTBS subgroups. Slab_SBS provided comparable bond strength to the μTBS of all substrates with adhesive mode of failure.

CONCLUSION

 Slab_SBS is easier to prepare with consistent and predictable outcome with no pretest failures during specimen preparation and better stress distribution.

Wear characteristics of esthetic resin matrix and zirconia reinforced lithium disilicate CAD/CAM materials: two-body wear and surface topography analysis

BACKGROUND

This in vitro study assessed the wear behavior of different CAD-CAM blocks and the abrasion of the enamel antagonist against these materials.

METHODS

64 disk-shaped specimens were prepared from 8 different CAD/CAM blocks as follow: one lithium disilicate glass ceramics block "IPS Emax CAD" as control group, two zirconia reinforced lithium silicate "Vita Suprinity & Celtra DUO," one interpenetrating network ceramic block "Vita Enamic," Three resin-based block composites "Lava Ultimate, Cerasmart & Brilliant-crios" as well as one hybrid nanoceramic "Shofu block HC". All specimens were mounted against canine and tested for two body wear analysis using a chewing simulating loading machine (100,000 cycles, 50 N, 5/55 °C). The amount of wear loss was measured for each specimen using a digital precise scale. Wear area before and after the chewing simulation were evaluated using an optical profilometer. Data analysed using one-way ANOVA test followed by Tukey's post hoc.

RESULTS

The results showed a significantly higher wear loss in resin matrix ceramics in comparison to glass ceramics. However, for tooth wear glass ceramics had significantly higher value than hybrid ceramics.

CONCLUSIONS

Resin based CAD/CAM Blocks gives a superior result when evaluating the wear behavior and its effect on the opposing tooth surface.

Effects of Immediate and Delayed Cementations for CAD/CAM Resin Block after Alumina Air Abrasion on Adhesion to Newly Developed Resin Cement

The purpose of this study was to evaluate the effect of one week of Computer-aided design/Computer-aided manufacturing (CAD/CAM) crown storage on the μTBS between resin cement and CAD/CAM resin composite blocks. The micro-tensile bond strength (μTBS) test groups were divided into 4 conditions. There are two types of CAD/CAM resin composite blocks, namely A block and P block (KATANA Avencia Block and KATANA Avencia P Block, Kuraray Noritake Dental, Tokyo, Japan) and two types of resin cements. Additionally, there are two curing methods (light cure and chemical cure) prior to the μTBS test—Immediate: cementation was performed immediately; Delay: cementation was conducted after one week of storage in air under laboratory conditions. The effect of Immediate and Delayed cementations were evaluated by a μTBS test, surface roughness measurements, light intensity measurements, water sorption measurements and Scanning electron microscope/Energy dispersive X-ray spectrometry (SEM/EDS) analysis. From the results of the μTBS test, we found that Delayed cementation showed significantly lower bond strength than that of Immediate cementation for both resin cements and both curing methods using A block. There was no significant difference between the two types of resin cements or two curing methods. Furthermore, water sorption of A block was significantly higher than that of P block. Within the limitations of this study, alumina air abrasion of CAD/CAM resin composite restorations should be performed immediately before bonding at the chairside to minimize the effect of humidity on bonding.

The effect of temporary sealing materials and cleaning protocols on the bond strength of resin cement applied to dentin using the resin-coating technique

This study evaluated the effect of temporary sealing materials and cleaning protocols on the bond strength of resin cement applied to dentin using resin-coating technique. Scotchbond Universal Adhesive and Filtek Supreme Ultra Flowable were applied to bovine dentin. Forty-five specimens were divided into the following three groups according to the temporary sealing materials: Cav-: CAVITON EX, Vas-: COCOA BUTTER and FIT SEAL, and Sep-: Washable SEP and FIT SEAL. Each material was placed on resin-coated dentin. After 1-week water storage, one of the following three cleaning protocols was performed: -WA: washed with water, -BR: brushed with PRESSAGE, and -AF: cleaned with AIR-FLOW. Microtensile bond strength test and EDS analysis were conducted. Irrespective of the cleaning protocol used, Washable SEP demonstrated less residual debris on resin-coated dentin, resulting in high bond strength. Regardless of the temporary sealing material applied, AIR-FLOW demonstrated less residual debris, resulting in high bond strength.

Influence of elapsed time between airborne-particle abrasion and bonding to zirconia bond strength

OBJECTIVE

The airborne-particle abrasion of zirconia with alumina particle (APA) has been reported to result in the durable bonding of appropriate adhesive luting systems. However, whether a delay between APA and the application of the adhesive luting material might affect the resulting bond strength and its durability is unknown.

METHODS

A total of 140 disc-shaped zirconia specimens were divided according to the elapsed time between the APA of zirconia and its bonding into 5 test groups (15 min, 1 h, 4 h, 24 h, and 72 h). The specimens were airborne-particle abraded with 50-μm Al₂O₃, and then stored at room temperature according to the test group (n = 28/group). Surface free energy (SFE) was measured for 12 specimens per group using a goniometer. For each group 16 Plexiglas tubes filled with composite resin were bonded to the zirconia specimens with an adhesive luting resin (Panavia 21). Tensile bond strength (TBS) was tested for subgroups of 8 specimens after water storage for 3 days and for 150 days with 37,500 thermal cycles.

RESULTS

SFE decreased significantly within 24 h after APA. TBS after 3 days of water storage ranged from 38.3 (1 h) to 28.4 MPa (24 h) and after 150 days with thermocycling from 38.3 (15 min) to 24.8 MPa (24 h).

SIGNIFICANCE

Based on these results, the time between the APA of zirconia and the application of adhesive materials should be minimized when bonding nonretentive zirconia restorations clinically.

Bonding performance of dispersed filler resin composite CAD/CAM blocks with different surface treatment protocols

The effect of various pretreatments on the bonding of a resin cement to resin-composite CAD/CAM blocks (RCBs) was examined. The surface of dispersed-filler RCBs (DF-RCBs) and a polymer infiltrated ceramic network RCB (PICN-RCB) was roughened using hydrofluoric acid etching (HF) or sandblasting, and followed by silanization and/or universal adhesive (UA) application. Microtensile bond strength (µTBS), surface roughness parameters (arithmetical mean height (Sa); developed interfacial area ratio (Sdr)), and critical surface energy (γ_c) were determined. For most DF-RCBs, the highest µTBS was obtained using HF+UA. UA application to DF-RCBs resulted in similar or higher µTBS compared to silanization, which indicates that silane treatment is not crucial for DF-RCBs, especially after HF. In contrast, the highest µTBS to PICN-RCB was obtained with silanization. Both roughening pretreatments significantly increased the surface roughness parameters and the γ_c of all RCBs. The γ_c was positively correlated with Sa (r=0.756, p<0.001) and Sdr (r=0.837, p<0.001).