The Journal of Adhesive Dentistry, 05/2019

Purpose: To systematically review the literature to determine whether the laboratory and clinical performance of glass-ionomer cement (GIC) is influenced by surface conditioning with polyacrylic acid (PAA). Materials and Methods: This systematic review was conducted according to PRISMA and registered in PROSPERO (CRD42016039305). A comprehensive literature search was conducted in seven electronic databases considering clinical and laboratory studies published up to July 2018, with no limit on year of publication. Two reviewers independently selected papers, extracted data, and assessed the risk of bias. Of 141 eligible studies, 23 were fully analyzed. A total of 15 studies (12 laboratory and three clinical trials) were included in the systematic review and three laboratory studies concerning the microtensile bond strength (μTBS) were included in the meta-analysis. Results: The meta-analysis showed that pretreating the surface with PAA before using GIC significantly improved the μTBS (OR = 3.17; 95% CI: 0.51-5.83; p = 0.02). In the longitudinal clinical trials, no significant difference was observed between applying PAA or not into the cavities before using GIC. Risk of bias was considered high in all study designs. Conclusion: Surface preconditioning with PAA has a positive effect on the bond strength of GIC. However, this finding was not confirmed in longitudinal clinical trials. Keywords: dental tissues, glass-ionomer cements, polyacrylic acid, systematic review

Purpose: To investigate the effects of grit blasting, acidic or alkaline/heat treatments, and metal primer application on the shear bond strength (SBS) of resin cement to machined commercially pure titanium (CP-Ti). Materials and Methods: Titanium plates were machined and received one of the following treatments: grit-blasting (GB), or grit-blasting followed by either acidic treatment (GB/AC) or alkaline/heat treatment (GB/AH). The specimens were randomly divided into 4 groups and treated with Rely X Ceramic Primer (RCP), Z Prime Plus (ZPP), and Alloy Primer (ALP), or without primer as the control. The pairs of titanium plates were cemented together with the Rely X Unicem cement. SBS was measured before and after thermocycling between 5°C and 55°C for 5000 cycles. Results: SEM observation showed that honeycomb-shaped pores formed on the surface of machined CP-Ti after GB/AC treatment, whereas a uniform net-like pattern formed after GB/AH treatment. In descending order, the surface roughness was GB, GB/AC, and GB/AH. The GB/AH group showed the highest SBS among all the treatments. As for primers, ALP group showed the highest SBS, while the RCP group showed the lowest. GB followed by ALP presented the highest SBS. Conclusion: A fine, uniform network structure was formed on the surface of CP-Ti following GB/AH treatment, providing an effective micromechanical interlocking mechanism for resin bonding. At the same time, after AH treatment, the -OH formed on the surface of the machined CP-Ti triggered a chemical reaction with the acid monomers in the resin adhesives, creating a chemical bond. As a result, GB/AH treatment significantly improved the bond strength relative to GB/AC treatment. In addition, ALP treatment facilitated the formation of hydrogen bonds, which further improved the chemical bond strength. Finally, the combination of the effects mentioned above resulted in the most robust bond between machined CP-Ti and the resin adhesives. Keywords: bond strength, resin cement, metal primer, pure titanium

Purpose: To evaluate the potential of an additional application of two novel hydrophobic experimental adhesive resins with or without bioactive zinc fluoride glass to promote the bond strength of a one-step self-etch universal adhesive. Materials and Methods: Three self-etch universal adhesives, G-Premio Bond (GPB), Scotchbond Universal (SBU) and Clearfil SE Bond 2 (SE2), and two experimental adhesive resins, BZF210 and BZF21, were used in this study; thus, five groups were formed: GPB, GPB+BZF210, GPB+BZF21, SBU, and SE2. The adhesives were applied to flat dentin surfaces according to each manufacturer's instructions. The microtensile bond strengths (μTBS) were evaluated after 24-h water storage. The fracture modes and interfacial structures were analyzed using SEM, while elemental analysis was performed using SEM-EDS. The data were analyzed using one-way ANOVA and the Games-Howell test (p 0.05). Results: Significantly higher μTBS was achieved by additional application of BZF210 (48.68 ± 6.59 MPa) and BZF21 (58.58 ± 2.84 MPa) compared with GPB (33.57 ± 4.22 MPa) alone. Most failures occurred above the smear layer in GBP, while more cohesive and mixed failures were observed in GBP+BZF210, GPB+BZF21, SBU, and SE2. The interfacial structures revealed that GBP+BZF210 and GPB+BZF21 had more and longer resin tags than did GPB. SEM-EDS showed a particularly high peak of zinc in GPB+BZF21. Conclusions: The bond strength of GPB was significantly improved by the additional application of BZF210 and BZF21. Using an additional bioactive hydrophobic layer on a one-step, self-etch universal adhesive can significantly improve its bonding efficacy and extend its clinical options. Keywords: adhesive, dental bonding, microtensile bond strength, scanning electron microscopy

Purpose: To evaluate the effect of human and bovine root dentin age on the bond strength of fiber posts fixed with resin cements. The degree of conversion (DC) of the resin cements in different root thirds also was evaluated. Materials and Methods: Ninety-six single-rooted teeth were divided into groups according to the origin and age: young human (20-30 years), old human (over 60 years), young bovine (24-36 months) and adult bovine (over 48 months). The teeth were endodontically treated, and fiber posts were cemented with resin cements (RelyX Ultimate and RelyX U200). After 24 h, the teeth were sectioned perpendicularly and the push-out test was performed in a universal testing machine at a speed of 0.5 mm/min, until failure. One specimen from each third from each group (n = 6) was selected, and the DC of the resin cements was analyzed by FT-Raman spectroscopy. Results: For both resin cements, the young human root dentin group presented the highest bond strengths and the old human root dentin group presented the lowest (p 0.05). The bond strengths of bovine root dentin groups were not affected by aging (p > 0.05). For the DC of resin cements, there were differences among the root thirds (p 0.05), with the lowest values observed in the apical third. Conclusions: The bond strengths were higher in the young human root canal than in the bovine substrate, with a negative effect of aging in the human substrate. The DC of dual-curing resin cements decreased from the coronal to apical root thirds. Keywords: root dentin, human tooth, bovine tooth, aging, bond strength, degree of conversion

Purpose: To assess the effect of different surface pretreatments on the shear bond strength of resin luting material on CAD-CAM composite resins and a polymer-infiltrated ceramic network (PICN). Materials and Methods: CAD-CAM materials (Brilliant Crios, Cerasmart, Lava Ultimate, VITA Enamic) were subjected to the following pretreatments: no pretreatment; grit blasting; grit blasting + silane; HF etching + silane; tribochemical silica coating + silane; manufacturers' specifications; manufacturers' specifications + silane; manufacturers' specifications using only the manufacturers' products including their recommended luting materials (DuoCem, G-Cem LinkForce, RelyX Ultimate, RelyX Unicem 2). Specimens were luted with resin luting material according to the Swiss shear test design. After six months of water storage, shear bond tests were performed. Data were analyzed with multiple linear regression models and nested models (α = 0.05). Results: Low bond strengths were obtained without pretreatment (Brilliant Crios 3.01 ± 0.54 MPa, Cerasmart 2.66 ± 0.47 MPa, Lava Ultimate 1.76 ± 0.26 MPa, VITA Enamic 2.83 ± 0.63 MPa). Grit blasting achieved high bond strengths across all materials (Brilliant Crios 5.17 ± 0.77 MPa, Cerasmart 4.27 ± 0.50 MPa, Lava Ultimate 3.98 ± 0.54 MPa, VITA Enamic 4.97 ± 0.90 MPa). Silane application tended to decrease bond strengths on CAD-CAM composite resins. Following the manufacturers' specifications and using their recommended materials achieved the highest bond strengths for all materials except Cerasmart (Brilliant Crios 5.75 ± 0.91 MPa, Cerasmart 2.82 ± 0.28 MPa, Lava Ultimate 6.63 ± 0.97 MPa, VITA Enamic 7.09 ± 0.77 MPa). Conclusion: Grit blasting and the application of a suitable material primer is a useful pretreatment for the bonding of CAD-CAM composite resins. Silane application on CAD-CAM composite resins may entail drawbacks, possibly owing to the scarcity of silanizable fillers. Keywords: silane primer, hydrofluoric acid etching, silica coating, air abrasion, adhesion