Effect of different surface treatments and retainer designs on the retention of posterior Pd-Ag porcelain-fused-to-metal resin-bonded fixed partial dentures

Abstract

The aim of this study was to investigate the adhesive property of palladium-silver alloy (Pd-Ag) and the simulated clinical performance of Pd-Ag porcelain-fused-to-metal (PFM), resin-bonded, fixed partial dentures (RBFPDs). A total of 40 Pd-Ag discs (diameter=5 mm) were prepared and divided into the following four groups (n=10): a) No sandblasting, used as a control; and b, 50 µm; c, 110 µm; and d, 250 µm aluminum oxide (Al2O3) particles, respectively. Another 50 discs were pre-sandblasted and divided into five groups (n=10) subjected to different treatments: e) Sandblasting, used as a control; f) silane; g) alloy primer; h) silica coating + silane and i) silica coating + alloy primer. All 90 discs were bonded to enamel with Panavia F 2.0 and then subjected to shear bond strength (SBS) testing. The fracture surfaces were examined by scanning electron microscopy. Next, 40 missing maxillary second premolar models were restored with one of the four following RBFPD designs (n=10): I) A premolar occlusal bar combined with molar double rests (MDR); II) both occlusal bars with a wing (OBB); III) a premolar occlusal bar combined with a molar dental band (MDB); and IV) two single rests adjacent to the edentulous space with a wing (SRB) used as a control. All specimens were aged with thermal cycling and mechanical loading. Subsequently, they were loaded until broken. The data were analyzed by one-way analysis of variance. Al2O3 (250 µm) abrasion provided the highest SBS (P<0.05). The alloy primer and silica + silane exhibited increased SBS. Furthermore, fracture analysis revealed that the failure mode varied among the different treatments. Whereas MDB exhibited the highest retention (P<0.05), that of OBB was greater than that of MDR (P<0.05), and the control exhibited the lowest retention. Abrasion with Al2O3 (250 µm) effectively increased the adhesive property of Pd-Ag. Additionally, treatment with the alloy primer and silica coating + silane was able to increase the adhesive property of abraded Pd-Ag. Under the present conditions, all three modified retainer types provided improved outcomes for Pd-Ag PFM RBFPDs compared with the control.

Management of Aphakia with Visual Axis Opacification after Congenital Cataract Surgery Based on UBM Image Features Analysis

“…It has been reported that hereditary hyperferritinemia cataract syndrome (HHCS) should be considered in the differential diagnosis of childhood hyperferritinemia, especially in the presence of normal transferrin saturation [ 13 ]. In some infants and young children due to the dense opacity of the posterior lens capsule, it is often necessary to increase the laser energy or increase the number of firings, which may aggravate the degree of damage of corneal endothelial cells and iris tissue and increase the incidence of complications [ 14 ]. Clinically, for patients who are only examined using a slit-lamp microscope or a surgical microscope, it is usually only possible to see the opacity of the two-dimensional planar pupil region, and it is not possible to distinguish whether the opacity is membranous or cortical residue or hyperplasia.…”

Materials used in rehabilitation of anterior teeth with Maryland adhesive bridge

“…(Tanoue N. et al, 2021) [28] As a combination of noble metals, the alloy requires surface treatment to improve its bonding, particularly when manufactured into resin-bonded prostheses. (Chen X et al, 2018) [4] .…”

Cantilevered resin bonded bridge: A conservative approach to restore periodontally compromised teeth- a case report.

“…Panavia 21) have helped increased the success rate of RBFPDs significantly. 8 Additionally, more variations have been developed to further improve retention and esthetics of the prosthesis e.g. all ceramic and fiber reinforced composite bridges.…”