RESUMO
PURPOSE: To investigate the effects of thermal cycling and surface roughness of metal implant abutments and the intaglio surface of the copings on the retentive properties of 4 provisional luting agents commonly used in the cementation of implant-retained fixed partial dentures (FPDs). MATERIALS AND METHODS: A 2-unit implant-retained FPD and a 4-unit implant-retained FPD were fabricated using gold-palladium alloy. The abutments used were 5 mm in height. The FPDs were cemented with 4 commonly used provisional luting agents and thermocycled for 700 cycles from 5 degrees C to 36 degrees C to 55 degrees C and were then subjected to tensile strength testing. After thermal cycling, the intaglio surfaces of the same FPDs and the abutments were air-abraded with 50 microm Al2O3 particles. FPDs were cemented using the same provisional cements, and after 24 hours of storage in 100% humidity, tensile strength tests were performed. Descriptive statistics, 2-way analysis of variance, Friedman's 2-way ANOVA, and Tukey's HSD test (alpha = .05) were performed. RESULTS: Both thermal cycling and air abrasion had a significant effect (P < .001) on the retentive values of all cements tested. A noneugenol provisional cement (Nogenol) exhibited the lowest mean retentive value after both thermal cycling and air abrasion for both the 2- and 4-unit FPD models. The urethane resin provisional cement (Improv) exhibited the highest mean retentive strength for both the 2- and 4-unit FPDs after thermal cycling and air abrasion treatments. CONCLUSIONS: Thermal cycling had a detrimental effect on the retentive properties of all cements tested. Air abrasion significantly improved the cement failure loads of the provisional luting agents used in the study and seems to be an effective way of increasing the retention of implant-retained FPDs.
