Influence of alloy microstructure on the microshear bond strength of basic alloys to a resin luting cement

Abstract

The aim of this study was to evaluate the influence of microstructure and composition of basic alloys on their microshear bond strength (µSBS) to resin luting cement. The alloys used were: Supreme Cast-V (SC), Tilite Star (TS), Wiron 99 (W9), VeraBond II (VBII), VeraBond (VB), Remanium (RM) and IPS d.SIGN 30 (IPS). Five wax patterns (13mm in diameter and 4mm height) were invested, and cast in a centrifugal casting machine for each basic alloy. The specimens were embedded in resin, polished with a SiC paper and sandblasted. After cleaning the metal surfaces, six tygon tubes (0.5 mm height and 0.75 mm in diameter) were placed on each alloy surface, the resin cement (Panavia F) was inserted, and the excess was removed before light-curing. After storage (24 h/37°C), the specimens were subjected to µSBS testing (0.5 mm/min). The data were subjected to a one-way repeated measures analysis of variance and Turkey's test (α=0.05). After polishing, their microstructures were revealed with specific conditioners. The highest µSBS (mean/standard deviation in MPa) were observed in the alloys with dendritic structure, eutectic formation or precipitation: VB (30.6/1.7), TS (29.8/0.9), SC (30.6/1.7), with the exception of IPS (31.1/0.9) which showed high µSBS but no eutectic formation. The W9 (28.1/1.5), VBII (25.9/2.0) and RM (25.9/0.9) showed the lowest µSBS and no eutectic formation. It seems that alloys with eutectic formation provide the highest µSBS values when bonded to a light-cured resin luting cement.

Microstructural evidence of beryllium in commercial dental Ni-Cr alloys

“…This phase presumably has been formed via a solid state reaction during cooling and should correspond to the intermetallic NiBe phase, based on the work of Hero et al 14 . Thus, the presence of this very characteristic eutectic is also a microstructural evidence of beryllium in the Ni-Cr base alloys, in agreement with results found in other papers 12,[14][15][16] . Bauer et al 15 found a lamellar eutectic in the microstructure of a certain alloy and suggested the possible existence of Be in its composition, although the manufacturer claimed the absence of Be in that alloy.…”

“…Thus, the presence of this very characteristic eutectic is also a microstructural evidence of beryllium in the Ni-Cr base alloys, in agreement with results found in other papers 12,[14][15][16] . Bauer et al 15 found a lamellar eutectic in the microstructure of a certain alloy and suggested the possible existence of Be in its composition, although the manufacturer claimed the absence of Be in that alloy. We consider that this typical eutectic microstructure observed in beryllium-containing Ni-Cr commercial alloys cannot be reproduced without the presence of this element.…”

An In Vitro Evaluation of the Effect of Various Adhesives and Surface Treatments on Bond Strength of Resin Cement to Polyetheretherketone

“…Although PEEK has significant advantages for dental applications, difficulties in establishing a strong and durable adhesion to dental material are the major clinical disadvantage . Current studies focus on enhancing PEEK surface for reacting with resins to allow bonding, because the clinical performance of fixed dental prostheses mainly relies on the luting procedure . Generally, two methods to obtain a strong bonding performance between the resin cement and PEEK have been the focus of recent studies: the alteration of the PEEK surface and conditioning with an adhesive system to enable the chemical interactions …”

“…Surface pretreatments arrange the PEEK surface for micromechanical bonding to resin; however, additional adhesives are essential in establishing a strong bond between PEEK and resin. Most studies reported that adhesive systems that contain methylmethacrylate (MMA) were able to constitute a sufficient bond to PEEK . Studies showed that the combination with pretreatments enhances the bond strength because mechanical treatments provide more functional groups to which the components of adhesive systems can bond …”

“…1,2,9 Current studies focus on enhancing PEEK surface for reacting with resins to allow bonding, because the clinical performance of fixed dental prostheses mainly relies on the luting procedure. 2,3,8,9 Generally, two methods to obtain a strong bonding performance between the resin cement and PEEK have been the focus of recent studies: the alteration of the PEEK surface and conditioning with an adhesive system to enable the chemical interactions. 9,10 Several studies have examined the bond strength between resin and PEEK material by various pretreatments such as sandblasting, silica coating, 11,12 treating the surface with piranha etching, 2,13 sulfuric acid, 14,15 or different types of plasma.…”