The effects of height and surface roughness of abutments and the type of cement on bond strength of cement-retained implant restorations.

OBJECTIVES

To evaluate the effects and interactions between cement type, abutment height and surface roughness on bond strength of cemented implant restorations.

MATERIALS AND METHODS

One hundred and sixty metal copings were fabricated and divided into 16 groups of 10 samples each. Copings were cemented on 4 and 6 mm height Alfa-Gate(®) abutment, using four types of cements: zinc phosphate (ZNP), glass ionomer (GI), and zinc oxide eugenol (ZOE) with or without 15% vaseline. Copings were removed using a universal testing machine and bond strengths were recorded. All abutments were sandblasted with 50 μm aluminum oxide and the experiment was repeated. Results were analyzed using univariate analysis, Games-Howell, and Bonferroni's pairwise comparisons tests at P≤0.05.

RESULTS

Bond strengths were significantly different according to cement type, abutment height, and surface roughness (P=0.001). The cement ranking from highest to lowest was: ZNP>GI>ZOE>zinc oxide eugenol with 15% vaseline (ZOEV). An increasing abutment height showed a significant increase in bond strength for permanent cements only (P≤0.05). Sandblasting abutment surface significantly the increased bond strength for all cement except the ZOEV at 4 mm abutment, and for only ZOE and GI cements at the 6 mm abutment (P≤0.05).

CONCLUSIONS

ZP was the strongest cement and required using one of the variables (height, surface roughness) for maximum bond strength. GI bond strength was increased by both variables but sandblasting was more effective. ZOE required using both variables to be as effective as some of the permanent cement subgroups. ZOEV was the weakest and bond strength was not improved by either variables.