Effect of cleaning methods on retentive values of saliva-contaminated implant-supported zirconia copings

The aim of this study was to evaluate the effect of different cleaning regimens on retentive strength of saliva-contaminated implant-supported zirconia copings.

Seventy solid titanium abutments with 5.5 mm height (Straumann) were attached to the regular neck implant analogs (Straumann). The abutment-analog complex was mounted vertically in an autopolymerized T-shaped acrylic resin block. Seventy zirconia copings with an occlusal loop were made. The copings were contaminated with fresh human saliva for 1 min (except the control group). Afterward, the specimens were washed with water spray for 15 s and dried for 15 s. The copings were divided into seven groups according to cleaning methods (n = 10). Group 1: no contamination (control group); Group 2: water spray rinsing; Group 3: airborne particle abrasion; Group 4: immersion in 96% isopropanol; Group 5: applying Ivoclean (Ivoclar Vivadent); Group 6: applying 1% sodium hypochlorite; and Group 7: applying Monobond Plus (Ivoclar Vivadent). The copings were luted with a resin luting agent (RelyX Unicem; 3M ESPE). After 5,000 thermal cycles, the retentive values of the restorations were tested using universal testing machine. The dislodging forces were analyzed using one-way analysis of variance and the Tukey's HSD tests (α = 0.05).

The copings, which were cleaned with Ivoclean and 96% isopropanol, showed the highest retentive values (204.79 ± 44.49 and 232.65 ± 71.36, respectively). There was a significant difference between the studied groups (F = 2.735; p = .02). Tukey's HSD showed that there was no significant difference between the different cleaning procedures and control group except water rinsing group (p = .14). The lowest retentive value was related to the saliva-contaminated group, which were only cleaned with water rinsing method.

The retentive values of zirconia-based restorations were adversely affected by saliva contaminations. These restorations can be cleaned by Ivoclean, 96% isopropanol, airborne particle abrasion, 1% sodium hypochlorite, or applying Monobond Plus before luting procedures.