In Vitro Evaluation Of Six Different Surface Treatments On The Shear Bond Strength Between Zirconia Ceramics And Self-adhesive Resin Cements

Objectives:The purpose of this study in vitro was to compare Shear Bond Strength(SBS)between Zirconia ceramics disposed with6different surface treatments and aself-adhesive resin cement and to help the dentists to choose the suitable cement inclinic.Methods:Zirconia ceramics(Upcera Dental,China) were cutted into blocks, and then weresintered according to the manufacturer's instructions.54qualified blocks wereselected,and then prepared as cuboids8.0mm in length and width and2.5mm inheight. Each block's bonding surface was wet polished with180-,360-,600-and1000-grit silicon carbide abrasive papers. All blocks were randomly divided into sixgroups(9for each group): group A: Ground with diamond grit bur(GDB); group B:Sandblasted with110-μm Al2O3particle(SAP); group C: Irradiated with the Er:YAGlaser(IER); group D: GDB plus Silica Coating(SC); group E: SAP plus SC; group F:IER plus SC. The silica coating was prepared by Sol-Gel progress.One block of eachgroup was selected for observing the surface topographies by SEM and analyzing theionic distribution character by EDS. The rest blocks of each group were used forshear bond strength test. Zirconia blocks that were treated with6different methodsmentioned above were embedded in autopolymerizing resin in order to makespecimens3.0mm in height and12.0mm in diameter. Then, the bonding surfaces ofzirconia specimens in D,E and F groups were coated with a thin film of silanecoupling agent.Two side sticky tape with a central hole5.0mm in diameter waspositioned over the surface of zirconia ceramic to define the bonding area. Then thecopper ring(6.0mm in internal diameter and2.0mm in height) was placed on thesticky tape. The self-adhensive resin cements(RelyXTMUnicem,RU) were injectedinto the copper ring, and illuminated40seconds by LED source. After that,thespecimens were stored in distilled water at37℃for24hours prior to testing. The SBS test was performed using a universal testing machine. Maximum shear load atthe point of failure was recorded, and the SBS was calculated. A single observerexamined the fractured specimen interface using SEM to evaluate failure mode. Thedata were analysised by using the statistical software SPSS13.0.Statistical analysis ofthe SBS was performed by multifactorial analysis and the Least-significantdifference(LSD) method was used for multiple paired comparisons(α=0.05).Results:1. In the two-factor ANOVA model, the main factors mechanical treatment andsilica coating of zirconia ceramics and all corresponding interactions were statisticallysignificant (P＜0.05).2.In subsequent separate one-factor ANOVA models and LSD method formechanical treatment,significant differences among all groups were found (P＜0.05),and SAP＞IER＞GDB for zirconia ceramics without silica coating(P＜0.05),and SAP+SC＞GDB+SC,IER+SC for zirconia ceramics with silica coating(P＜0.05). and there was no statistically significant difference between GDB+SC andIER+SC group(P＞0.05). In one-factor ANOVA models for silica coating of zirconiaceramic, significant differences between groups were found (P＜0.05),and GDB+SC＞GDB,SAP+SC＞SAP,IER+SC＞IER.3.Failure modes of all mechanical treatment specimens were adhesive failurebetween the RU-zirconia ceramic bonding interface,and most of specimens treatedwith mechanical treatment plus silica coating were mixed failure.Conclusions:1.Sandblasting with110-μm Al2O3particle, irradiating with the Er:YAG laserand grinding with diamond grit bur can be all used as surface treatment methods ofzirconia ceramics.All of them can rough the surface of ceramics and increase thebond strength between zirconia ceramics and self-adhensive resin cements. Amongthe three methods, sandblasting shows the best effect to increase the bond strength.2.The sol-gel process is an effective way to prepare silica coating on zirconiaceramic.The silica coating can increase the silicon element content of zirconiaceramic.Silica coating combining with silane coupling agent can improve the bondstrength between zirconia ceramic and self-adhensive resin cement. 3.The combination of zirconia ceramic and SiO2film can be promoted bysandblasting before silica coating.