Influence of different airborne-particle abrasion pressures, cleaning methods, and artificial aging on zirconia ceramic bonding.

Abstract

Statement of problem: Airborne-particle abrasion (APA) with alumina combined with a primer or luting resin containing a phosphate monomer has been well established for resin bonding to zirconia. However, a standardized method for bonding to zirconia is unavailable, as some factors including the optimal pressure of airborne-particle abrasion, the cleaning method, and the luting resin system are still unclear because of the limited available data.

Purpose: The purpose of this in vitro study was to evaluate the influence of different airborne-particle abrasion pressures and different cleaning methods of zirconia on the tensile bond strength (TBS) of 2 luting resins system containing methylacryloyloxydecyl-dihydrogenphosphate (MDP) either in the primer or in the luting resin.

Material and methods: A total of 128 disk specimens were milled from zirconia blocks and divided into groups according to the pressure of airborne-particle abrasion of either 0.1 MPa or 0.25 MPa (n=64). The specimens were then divided into 2 subgroups and were either cleaned in an ultrasonic device in isopropanol or with oil-free air stream (n=32). The subgroups were further divided according to the luting resin (n=16) and the bonding surfaces were perpendicularly luted to the acrylic resin tubes filled with a composite resin (Clearfil F II) with either an MDP-containing primer and a luting resin or with a self-adhesive MDP-containing luting resin. Each of the 8 groups was further divided into 2 subgroups (n=8) with either 3-days water storage at 37 °C or 150-days water storage with additional thermal cycling (37 500 thermal cycles between 5 °C and 55 °C) for artificial aging. The TBS was evaluated with a universal testing machine. All specimens underwent failure mode analysis. Statistical analysis was performed with 4-way ANOVA and, if required, with 3-way ANOVA (α=.05).

Results: The mean ±standard deviations ranged from 57.0 ±11.1 MPa to 61.5 ±7.1 MPa after 3 days and from 32.3 ±11.7 MPa to 61.0 ±12.4 MPa after 150 days. The pressure of airborne-particle abrasion and the cleaning method had no significant effect on the TBS (P>.05), whereas the luting resin and artificial aging significantly influenced the TBS (P<.05).

Conclusions: Irrespective of the pressure of airborne-particle abrasion and the cleaning method, the use of an MDP-containing luting resin for bonding to zirconia was found to be more advantageous compared with an MDP-containing primer and luting resin because of higher bond strength and no significant decrease after artificial aging.