Effectiveness of Self-Adhesive Resin Luting Cement in CAD-CAM Blocks-A Systematic Review and Meta-Analysis

Bonding effectiveness of multi-step adhesive resin cements to CAD/CAM blocks: impact of thermal cycling and surface treatment methods

BACKGROUND

To investigate the effects of thermal cycling and surface treatment methods on the bonding effectiveness of multi-step resin cements to CAD/CAM blocks.

METHODS

A total of 198 slices, 66 each from CAD/CAM blocks (feldspathic ceramic: Vitablocs TriLuxe Forte, V; resin matrix ceramics (RMCs): Cerasmart, C; and Shofu Block HC, S), were obtained and randomly divided into two subgroups for etching with hydrofluoric acid (HFA) and sandblasting with Al2O3 (SB). After the surface treatments, one etched and one sandblasted sample of each CAD/CAM block was observed via SEM analysis at 500× magnification. The remaining 32 etched and 32 sandblasted samples of each CAD/CAM block were divided into two subgroups to be cemented with total-etch (TE) and self-etch (SE) resin cements. Then, half of the 16 samples in all the subgroups were subjected to aging (TC) for 5000 cycles (n = 8). The shear bond strength (SBS) of each sample was measured. Four-way analysis of variance (ANOVA) and Tukey tests were used to analyze the data (p < 0.05).

RESULTS

With or without TC, the highest SBS values for V were obtained with the HFA-TE and HFA-SE interactions, respectively. C presented the highest SBS values with HFA-SE and SB-TE interactions, whereas S presented the highest SBS values with SB-TE and HFA-TE interactions. Except the SB-SE interaction, C presented lower SBS values after TC than other materials. HFA created less porosity on the C and S surfaces than V. SB visibly roughened the surfaces of all the materials but caused fractures, cracks, and damage to the surfaces.

CONCLUSION

Similar SBS values can be achieved between feldspathics, RMCs, and multi-step adhesive resins with both HFA and SB treatments. However, the SBS values obtained from the SB-SE interaction may be below the recommended threshold values for all materials after TC. SB can cause distinctive cavities, fissures, and damage, especially on the surfaces of RMCs.

Bond strength of 4META-MMA-TBB resin to a CAD/CAM composite resin block and analysis of acetone-insoluble cured resin residues at adhesive interfaces

This study investigated the adhesion of 4META-MMA-TBB resin to CAD/CAM composite resin blocks. CAD/CAM composite resin blocks were subjected to alumina blasting, ceramic primer treatment, or both, and then bonded with 4META-MMA-TBB resin. The tensile bond strength of 4META-MMA-TBB resin to blocks without surface treatment was approximately 20 MPa, but with surface treatment, it significantly improved to approximately 40 MPa. Cohesive failure was observed in some blocks with surface treatment with both alumina blasting and ceramic primer. As a result of Soxhlet extraction of the adhesive interface with acetone solvent and FT-IR spectrum analysis, it was found that PMMA remained on the block surface when surface treatment with both alumina blasting and ceramic primer were performed. These results demonstrated that the bond strength of 4META-MMA-TBB resin is significantly improved when both alumina blasting and ceramic primer are applied as surface pretreatment to the CAD/CAM composite resin block.

Material properties and finite element analysis of adhesive cements used for zirconia crowns on dental implants

This study aimed to evaluate the material properties of four dental cements, analyze the stress distribution on the cement layer under various loading conditions, and perform failure analysis on the fractured specimens retrieved from mechanical tests. Microhardness indentation testing is used to measure material hardness microscopically with a diamond indenter. The hardness and elastic moduli of three self-adhesive resin cements (SARC), namely, DEN CEM (DENTEX, Changchun, China), Denali (Glidewell Laboratories, CA, USA), and Glidewell Experimental SARC (GES-Glidewell Laboratories, CA, USA), and a resin-modified glass ionomer (RMGI-Glidewell Laboratories, CA, USA) cement, were measured using microhardness indentation. These values were used in the subsequent Finite Element Analysis (FEA) to analyze the von Mises stress distribution on the cement layer of a 3D implant model constructed in SOLIDWORKS under different mechanical forces. Failure analysis was performed on the fractured specimens retrieved from prior mechanical tests. All the cements, except Denali, had elastic moduli comparable to dentin (8-15 GPa). RMGI with primer and GES cements exhibited the lowest von Mises stresses under tensile and compressive loads. Stress distribution under tensile and compressive loads correlated well with experimental tests, unlike oblique loads. Failure analysis revealed that damages on the abutment and screw vary significantly with loading direction. GES and RMGI cement with primer (Glidewell Laboratories, CA, USA) may be suitable options for cement-retained zirconia crowns on titanium abutments. Adding fillets to the screw thread crests can potentially reduce the extent of the damage under load.

Shear Bond Strength of Simulated Single-Retainer Resin-Bonded Bridges Made of Four CAD/CAM Materials for Maxillary Lateral Incisor Agenesis Rehabilitation

OBJECTIVES

 Maxillary lateral incisor agenesis (MLIA), treated orthodontically by space opening, requires complimentary aesthetic rehabilitation. Resin-bonded bridges (RBBs) can be equated as interim rehabilitation until skeletal maturity is achieved to place an implant-supported crown or as definitive rehabilitation in case of financial restrictions or implant contraindications. Scientific evidence of the best material must be confirmed in specific clinical situations. Computer-aided design and computer-aided manufacturing (CAD/CAM) materials are promising versatile restorative options. This study aimed to identify a straightforward material to deliver interim or definitive RBBs for nonprepared tooth replacement in MLIA.

MATERIALS AND METHODS

 Single-retainer RBB made from CAD/CAM ceramic blocks (Vita Enamic [ENA], Suprinity [SUP], and zirconia [Y-ZPT]) and a three-dimensional (3D) printed material (acrylonitrile butadiene styrene [ABS]) were evaluated by shear bond strength (SBS) and mode of failure, after adherence to an artificial tooth with RelyX Ultimate used in a three-step adhesive strategy.

STATISTICAL ANALYSIS

 The load to fracture (N) was recorded, and the mean shear stress (MPa) was calculated with standard deviations (SD) for each group and compared between materials using boxplot graphics. One-way analysis of variance (ANOVA) followed by the Tukey-Kramer post hoc test was used to compare the differences (α = 0.05). A meta-analysis focusing on CAD/CAM materials evaluated the magnitude of the difference between groups based on differences in means and effect sizes (α = 0.05; 95% confidence interval [CI]; Z-value = 1.96). Failure mode was determined by microscopic observation and correlated with the maximum load to fracture of the specimen.

RESULTS

 The mean ± SD SBS values were ENA (24.24 ± 9.05 MPa) < ABS (24.01 ± 1.94 MPa) < SUP (29.17 ± 4.78 MPa) < Y-ZPT (37.43 ± 12.20 MPa). The failure modes were mainly adhesive for Y-ZPT, cohesive for SUP and ENA, and cohesive with plastic deformation for ABS.

CONCLUSION

 Vita Enamic, Suprinity, Y-ZPT zirconia, and 3D-printed ABS RBBs are optional materials for rehabilitating MLIA. The option for each material is conditioned to estimate the time of use and necessity of removal for orthodontic or surgical techniques.

Influence of different immediate dentin sealing strategies on bond strength of indirect resin nanoceramic restorations

In this study, we evaluated the effect of four different strategies for bonding a CAD/CAM resin nanoceramic restoration (Lava Ultimate, 3M) to the dentin surface using a universal adhesive (Scotch Bond Universal, 3M) and adhesive resin cement (RelyX Ultimate, 3M) on the shear bond strength (SBS) and failure mode. The strategies comprised: (i) immediate sealing, immediate bonding; (ii) immediate sealing, bonding after 2 weeks with provisional restoration; (iii) immediate sealing with flowable resin composite reinforcement and bonding after 2 weeks with provisional restoration; and (iv) no immediate sealing, and bonding after 2 weeks with provisional restoration. After bonding, all the specimens were thermocycled, shear tests were performed using a universal testing machine, and failure modes were determined using stereomicroscope and scanning electron microscopy. The highest mean SBS was recorded with immediate sealing, immediate bonding strategy. Most adhesive failures with exposed dentinal tubules were noted in specimens exposed to bonding after 2 weeks with no immediate sealing, which was associated with the lowest SBS. Mixed failures predominated in all immediate dentin sealing groups. Immediate sealing with universal adhesives improves SBS, particularly in the single-visit approach, which has shown significantly better performance, whereas the provisional phase has a negative effect.

Dental Resin-Based Luting Materials-Review

As cementation represents the last stage of the work involved in making various indirect restorations (metal ceramic crowns and bridges, full ceramic crowns and bridges, inlays, onlays, and fiber posts), its quality significantly contributes to the clinical success of the therapy performed. In the last two decades, the demand for ceramic indirect restorations in everyday dental practice has considerably increased primarily due to the growing significance of esthetics among patients, but also as a result of hypersensitivity reactions to dental alloys in some individuals. In this context, it is essential to ensure a permanent and reliable adhesive bond between the indirect restoration and the tooth structure, as this is the key to the success of aesthetic restorations. Resin-based luting materials benefit from excellent optical (aesthetic) and mechanical properties, as well as from providing a strong and durable adhesive bond between the restoration and the tooth. For this reason, resin cements are a reliable choice of material for cementing polycrystalline ceramic restorations. The current dental material market offers a wide range of resin cement with diverse and continually advancing properties. In response, we wish to note that the interest in the properties of resin-based cements among clinicians has existed for many years. Yet, despite extensive research on the subject and the resulting continued improvements in the quality of these materials, there is still no ideal resin-based cement on the market. The manuscript authors were guided by this fact when writing the article content, as the aim was to provide a concise overview of the composition, properties, and current trends, as well as some future guidelines for research in this field that would be beneficial for dental practitioners as well as the scientific community. It is extremely important to provide reliable and succinct information and guidelines for resin luting materials for dental dental practitioners.