Effect of glass-ceramic coating versus alumina air-abrasion on the bond strength and residual stress of zirconia.

OBJECTIVES: To assess the effect of glass-ceramic coated zirconia versus alumina air-abraded zirconia on the shear bond strength (SBS) of resin cement and investigate the residual stresses present on both mechanically pre-treated surfaces. MATERIALS AND METHODS: A total of 180 zirconia disks, with diameters of 10 mm and 5 mm, were divided into two groups: DCMhotbond glass-ceramic coated, followed by hydrofluoric acid etching (DCM), and alumina air-abraded (AB). All mechanically pre-treated disks were conditioned with G-Multi Primer and bonded using G-Cem Linkforce Cement. Ninety specimens were immersed in distilled water for 24 h and subsequently allocated into three groups based on aging conditions (n = 15/subgroups): immediate testing, 5000 thermal cycles, and 10,000 thermal cycles. Then, the shear bond strength was assessed, and the obtained data were subjected to analysis using a two-way ANOVA, followed by a one-way ANOVA and Tukey's HSD post hoc test (α = 0.05). The residual stresses present on both mechanically pre-treated surfaces were examined using X-ray diffraction analysis. RESULTS: The mean SBS values of the DCM and AB groups showed no significant difference under each aging condition. The SBS of DCM groups was not affected by thermal cycles, whereas the SBS of AB groups exhibited a significant decrease following thermal cycles. Glass-ceramic coated surfaces exhibited higher compressive stresses than alumina air-abrasion. CONCLUSIONS: The DCMhotbond glass-ceramic coated zirconia showed comparable bond strength to the alumina air-abrasion technique. CLINICAL RELEVANCE: The DCMhotbond glass-ceramic coating technique is a promising alternative for zirconia surface pre-treatment. However, further investigations are needed before suggesting its clinical use.

Effective luting agents for glass-fiber posts: A network meta-analysis.

OBJECTIVES: The aims of this study were to systematically review the literature and compare the relative effects of various luting agents on bonding between glass-fiber posts and root canal dentin in short- and long-term aging conditions. DATA/SOURCES: The literature was electronically searched in PubMed, Embase, and Scopus. A manual search was performed by scanning the reference lists of the included studies. STUDY SELECTION: Two reviewers independently conducted the selection of studies, data extraction, and risk of bias assessment. Pairwise meta-analyses were based on random effect models. Network meta-analyses were conducted within a frequentist framework with a multivariable random effects approach. The standardized mean difference and 95% confidence interval was calculated. RESULTS: One hundred and eighteen studies were included and assessed the effects of five luting agents. For pairwise meta-analyses, in short-term aging conditions, a significantly higher bond strength of self-adhesive resin cement (SARC) compared to etch-and-rinse adhesive composite resin core material (ERCM) in the total, coronal, and middle regions. In long-term aging conditions, a significantly higher bond strength of ERCM compared to etch-and-rinse adhesive resin cement (ERRC) in all regions. Furthermore, SARC showed a significantly higher bond strength compared to self-etch adhesive composite resin core material (SECM) in the total, middle, and apical regions. For network meta-analyses, in the apical region, a significantly higher bond strength of SARC compared to ERRC in both aging conditions. CONCLUSIONS: The SARC tended to be the most effective luting agent in bonding between glass-fiber posts and root canal dentin in short- and long-term aging conditions.

Influence of a Novel Lithium Disilicate Coating on Composite-Zirconia Bonding and Bond Characterization.

PURPOSE: To investigate microtensile bond strength and characterization with the novel lithium disilicate coating technique compared to conventional air abrasion. MATERIALS AND METHODS: Eight zirconia blocks were fabricated and assigned to two groups (n = 4 each): (1) Lithium disilicate coating followed by hydrofluoric acid etching and Monobond N Primer (LiDi group); and (2) alumina air abrasion (MUL group). For each group, two identically pretreated zirconia blocks were bonded together with Multilink Speed Cement and cut into 30 stick-shaped specimens (1 × 1 × 9 mm3). The 120 specimens were stored in water for 24 hours and assigned to one of three groups (n = 20/group): (1) short-term storage for 24 hours; (2) thermocycling for 5,000 cycles; and (3) thermocycling for 10,000 cycles. A microtensile bond strength test was performed and evaluated. The bond strength results were analyzed using two-way ANOVA followed by one-way ANOVA and Tukey HSD (α = .05). Energy-dispersive x-ray spectroscopy (EDS), Fourier-transform infrared (FTIR), x-ray diffraction (XRD), focused ion beam scanning electron microscopy (FIB-SEM), and scanning electron microscopy (SEM) were used for chemical, crystalline phase, and failure mode analyses. RESULTS: The MUL groups recorded higher bond strength than the LiDi groups. Thermocycling significantly decreased the bond strength in both groups. Chemical analyses suggested that the lithium disilicate layer underwent hydrolysis, which compromised long-term bond strength. CONCLUSION: The bond between composite cement and alumina-abraded zirconia performed better than that with the lithium disilicate coating technique. Int J Prosthodont 2023;36:172-180. doi: 10.11607/ijp.6744.

Cleaning methods of contaminated zirconia: A systematic review and meta-analysis.

OBJECTIVES: The aims of this study were to systematically review the literature and statistically analyze the effectiveness of different cleaning methods on the bond strength of resin cement to zirconia in short- and long-term aging conditions. DATA/SOURCES: The literature was electronically searched in PubMed (MEDLINE), EMBASE, Wiley, Scopus, and Open Access Theses and Dissertations databases to select relevant articles that evaluated the bond strength between contaminated zirconia and resin cements. A manual search was performed by scanning the reference lists of included studies. STUDY SELECTION: All articles were published online before April 2022 and in English. Meta-analyses were conducted using random effects models to calculate standardized mean differences (SMD) between uncontaminated zirconia and various cleaning methods in two aging conditions (short- and long-term). Statistical heterogeneity was assessed using I-square statistics. The risk of bias of all included studies was assessed. All statistical analyses were conducted using STATA (StataCorp, College Station, Texas). RESULTS: Of the 1181 studies, 25 studies met the inclusion criteria for qualitative analyses. In short-term aging condition, cleaning contaminated zirconia with water, alcohol, or acid etching reported significantly lower bond strength than uncontaminated zirconia. For long-term aging condition, cleaning contaminated zirconia with water, cleaning agents, alcohol, or acid etching reported significantly lower bond strength than uncontaminated zirconia. Alumina air-abrasion or cleaning with sodium hypochlorite were comparable to uncontaminated zirconia for both short- and long-term aging conditions. CONCLUSIONS: This meta-analysis appeared to indicate that the cleaning methods of contaminated zirconia restoration have an effect on zirconia bonding.

Comparison of different artificial landmarks and scanning patterns on the complete-arch implant intraoral digital scans.

OBJECTIVES: The purpose of this study was to compare the effects of four types of artificial landmarks and three different scanning patterns on the accuracy of complete-arch implant intraoral digital scans. METHODS: An edentulous mandibular model with 4 dental implants (Osstem) was prepared as the master reference model (MRM) and scanned with laboratory scanner (E4 Lab Scanner®). Then, the model was modified with four artificial landmarks: (i) CON- unmodified MRM, (ii) PIP- pressure-indicating paste brushed over the edentulous ridge, (iii) LD- liquid dam markers placed on the edentulous ridge, and (iv) FL- floss tied with pattern resin between the scan bodies. In each group, the modified model was scanned with three different scanning patterns: (i) LB- linguo-buccal pattern, (ii) SS- s-shaped pattern, and (iii) QU- quadrant pattern (n = 10/subgroup) using an intraoral scanner (Trios®4). Scans in STL format were exported and superimposed with MRM file using an inspection software (Geomagic Control X). Accuracy (trueness and precision) was evaluated by calculating the deviation, root mean square (RMS). Results were analyzed using two-way ANOVA, one-way ANOVA and Games-Howell (α = 0.05). RESULTS: Significant differences in accuracy values were found across different artificial landmarks and scanning patterns as the LD artificial landmark with QU pattern showed the highest accuracy. The lowest accuracy was recorded in CON with LB pattern, PIP artificial landmark with LB pattern, and FL artificial landmark with SS pattern. CONCLUSIONS: The artificial landmarks and scanning patterns had a significant effect on the accuracy of the complete-arch implant intraoral digital scans. CLINICAL SIGNIFICANCE: When performing complete-arch digital scans with four dental implants, clinicians should select proper artificial landmark and scanning pattern, as the artificial landmark and scanning pattern significantly affect the accuracy of the scan when using an intraoral scanner. ®.

Influence of ceramic-coating techniques on composite-zirconia bonding: Strain energy release rate evaluation.

OBJECTIVES: To compare ceramic-coating techniques versus conventional techniques on bonding between composite cements and zirconia by means of strain energy release rate (Gc, J/m2). METHODS: Two sizes of zirconia bars (30 mm × 8 mm × 1.5 mm and 14.8 mm × 8 mm × 1.5 mm) were fabricated. Two smaller bars were treated and cemented to the surface of a large bar using one of the following methods: (i) AlN-nano-structured alumina coating with RelyX Unicem 2; (ii) HOT-DCM hotbond coating with G-Multi Primer and G-Cem Linkforce; (iii) LiDi-lithium disilicate glass-ceramic coating with Monobond N Primer and Multilink Speed; (iv) COJ-tribochemical silica treatment with RelyX Ceramic Primer and RelyX Unicem 2; (v) GCEM-alumina grit blasting with G-Multi Primer and G-Cem LinkForce; (vi) MUL-alumina grit blasting with Multilink Speed; and (vii) PAN-alumina grit blasting with Clearfil Ceramic Primer and Panavia F2.0. A total of 30 bilayered specimens in each group were stored in distilled water at 37 °C for 24 h and assigned to three subgroups (n = 10/test group): short-term test, thermocycling for 5000 cycles, and thermocycling for 10,000 cycles and tested in 4-point bending configuration. Results were analysed using two-way ANOVA, followed by one-way ANOVA and Games-Howell (α = 0.05). Failure mode and surfaces were analysed using optical microscopy and SEM. RESULTS: The bonding (J/m2) of COJ and MUL groups was significantly higher than the other groups among all aging conditions. Thermocycling affected the bonding in COJ and GCEM groups. SIGNIFICANCE: Surface pre-treatments and artificial aging affect the bonding between composite cements and zirconia.

Shear Bond Strength of Composite Cement to Lithium-Disilicate Glass-coated Zirconia Versus Alumina Air-abraded Zirconia.

PURPOSE: To compare the shear bond strength of composite cement to lithium-disilicate glass-ceramic coated zirconia vs to alumina air-abraded zirconia and to analyze the residual stresses on both of lithium-disilicate glass-ceramic coated zirconia vs alumina air-abraded zirconia specimens. MATERIALS AND METHODS: One hundred eighty zirconia disks (diameters 10 mm and 5 mm, 4.5 mm thick) were divided into two groups: lithium-disilicate glass-ceramic coating followed by hydrofluoric acid etching and Monobond N Primer (LiDi) or alumina air-abrasion (AA). For each group, two different sizes of identically pre-treated zirconia specimens were bonded with Multilink Speed Cement. A total of 90 specimens were stored in distilled water at 37°C for 24 h and then assigned to three subgroups (n = 15/test group): 1. short-term test; 2. thermocycling for 5000 cycles; 3. thermocycling for 10,000 cycles. Bond strength was tested in shear mode and results were analyzed using two-way ANOVA, followed by one-way ANOVA and Tukey's HSD (α = 0.05). Failure mode and surfaces were analyzed with optical and scanning electron microscopy. X-ray diffraction was used to analyze t-m phase transformation and residual stresses on mechanically pre-treated LiDi and AA surfaces. RESULTS: The LiDi groups recorded higher mean bond strength than AA groups after thermocycling (p < 0.05). Thermocycling did not affect the bond strength of either LiDi or AA groups (p > 0.05). Most of specimens in AA groups exhibited mixed failure. Alumina air-abraded surfaces exhibited higher residual compressive stresses than did surfaces with a lithium-disilicate glass-ceramic coating. CONCLUSION: Following thermocycling, composite-zirconia bond strength of specimens with a lithium-disilicate glass-ceramic coating was greater than that of alumina air-abraded specimens.

Shear bond strength of composite cement to alumina-coated versus tribochemical silica-treated zirconia.

OBJECTIVES: To compare the shear bond strength of composite-resin cement to nano-structured alumina-coated versus to tribochemical silica-treated zirconia, and to analyze the residual stresses on both of nano-structured alumina-coated versus tribochemical silica-treated zirconia specimens. METHODS: One hundred and eighty zirconia disks (10 mm and 5 mm in diameter, 5 mm thickness) were divided into two groups: nano-structured alumina coating (H.C.Starck, AlN) and tribochemical silica treatment (CoJet) followed by RelyX Ceramic Primer (COJ). For each group, two different sizes of identically pre-treated zirconia specimens were bonded together with RelyX Unicem 2 Cement. A total of 90 specimens were stored in distilled water at 37 °C for 24 h and then further assigned to three groups (n = 15/test group): short-term test, thermocycling for 5000 cycles, and thermocycling for 10,000 cycles. Bond strength was tested in shear mode and results were analyzed using two-way ANOVA, followed by one-way ANOVA and Tukey's HSD (α = 0.05). Failure mode and surfaces were analyzed with optical microscopy and SEM. X-ray diffraction (XRD) were used for t-m phase transformation and residual stress analysis on mechanically pre-treated AlN and COJ surfaces. RESULTS: The mean bond strengths of AlN and COJ groups were not statistically different after thermocycling (p > 0.05). However, when compare to 24 h only the bond strength of the COJ groups decreased significantly after thermocycling (p < 0.05). Most of specimens in both AlN and COJ groups exhibited adhesive failure. Compressive stresses were detected on both mechanically pre-treated AlN and COJ surfaces, with significant differences in stress values. CONCLUSION: Following thermocycling, composite-zirconia bond strength of nano-structured alumina coating was comparable to that of tribochemical silica treatment.

Influence of glass-ceramic coating on composite zirconia bonding and its characterization.

OBJECTIVE: The aims of this study were to compare micro-tensile bond strength and characterize the bond of ceramic-coated versus air-abraded and chemically treated zirconia specimens. METHODS: Eight zirconia blocks were fabricated and assigned to two groups as follows: AA-alumina air-abrasion; and CC-DCMhotbond coating followed by alumina air-abrasion and hydrofluoric acid etching. For each group, two identically pre-treated zirconia blocks were applied G-Multi Primer, cemented together with G-Cem Linkforce cement and cut into 30 stick-shaped specimens (1×1×9mm3). A total of 120 specimens were stored in distilled water for 24h and then assigned to three groups: (i) short-term test, (ii) thermocycling for 5000, and (iii) thermocycling for 10,000 cycles. The specimens were tested in tensile mode. The bond strength results were analyzed using two-way ANOVA, followed by one-way ANOVA and Dunnett T3 (α=0.05). Failure mode and surfaces were analyzed with optical microscopy and SEM. The EDS, FTIR, XRD, and FIB-SEM were used for chemical, crystalline phase analyses. RESULTS: The AA groups recorded higher mean bond strength than the CC groups in all aging conditions. Thermocycling did not affect the bond strength of the AA groups, whereas the bond strength of the CC groups decreased significantly after aging. The MDP monomer and silane in G-Multi Primer chemically reacted with mechanically pre-treated AA and CC surfaces via the absorption of P-O and Si-O groups. SIGNIFICANCE: The bond strength of a conventional protocol involving alumina air-abrasion was greater than ceramic coating technique.

Influence of Nano-structured Alumina Coating on Composite-Zirconia Bonding and its Characterization.

PURPOSE: To compare microtensile bond strength and characterize the bond of nano-structured alumina-coated vs tribochemically silica-treated zirconia specimens. MATERIALS AND METHODS: Eight zirconia blocks were assigned to two groups: nano-structured alumina coating (AlN) and tribochemical silica treatment (CoJet) followed by RelyX Ceramic Primer (COJ). For each group, two identically pre-treated zirconia blocks were bonded with RelyX Unicem 2 Cement and cut into 30 stick-shaped specimens (1 x 1 x 9 mm3). A total of 120 specimens were stored in distilled water at 37°C for 24 h and then assigned to three groups (n = 20/test group): short-term test, thermocycling 5000 cycles, and thermocycling 10,000 cycles. The specimens were tested in tensile mode. The bond strength results were analyzed using two-way ANOVA, followed by one-way ANOVA and Tukey's HSD (α = 0.05). Failure mode and surfaces were analyzed with optical microscopy and SEM. FTIR and EDS were used for chemical analyses on primer-, mechanically and/or chemically pre-treated surfaces. RESULTS: The mean bond strengths of AlN and COJ groups were not statistically significantly different in all aging conditions (p > 0.05). Thermocycling significantly decreased the bond strength of both groups (p < 0.01). The AlN groups exhibited predominantly either adhesive or mixed failure, whereas the specimens in the COJ groups mainly presented either mixed or cohesive failure in composite cement. Silane chemically reacted with mechanically pre-treated COJ surface via the absorption of Si-O group. CONCLUSION: The composite-zirconia bond strength after application of a nano-structured alumina coating was comparable to that after tribochemical silica treatment.

Bonding of composite cements to zirconia: A systematic review and meta-analysis of in vitro studies.

OBJECTIVES: The aim of this study was to systematically review the literature and statistically analyze bond strength data to identify the influence that composite cements, type of test methodology, chemical and mechanical pre-treatments have on the bond strength of composite cements to zirconia in three different artificial aging conditions. METHODS: The literature was electronically searched in MEDLINE, PUBMED, EMBASE, and SCOPUS to select relevant articles that evaluated the bond strength between zirconia and composite cements. A manual search was performed by scanning the reference lists of included studies. All articles were published online before December 2016 and in English. From electronic database and manual searches, 444 studies were identified; 161 articles with 1632 test results met the inclusion criteria. Test results were assigned into 3 aging conditions: non-aged, intermediate-aged and aged groups. Generalized estimating equations (GEE) were used to explore actual mean bond strengths. As the bond strength is a non-negative value, lognormal distribution was used. RESULTS: In non-aged condition, data showed statistically significant interactions between cement type and type of test. There was no statistically significant interaction between mechanical and chemical pre-treatments. In intermediate-aged and aged conditions, data showed no statistically significant interactions between mechanical and chemical pre-treatments and between cement type and type of test. CONCLUSIONS: This meta-analysis appeared to indicate that mechanical pre-treatments, and in particular ceramic coating, combined with methacryloyloxydecyl dihydrogen phosphate (MDP) containing primers yielded the highest long-term bond strength (aged-condition). However, data are limited and caution should be exercised before applying these results to clinical situations.