Purpose:The desirable properties of a luting agent used for implant prostheses are adequate tensile strength for retention and at the same time render the crowns to be retrievable. No studies have reported a comparison of the retention of implant crowns luted with zinc phosphate and polymeric cements. Studying the retentive abilities of these cements utilizing varying sizes of implant abutments may provide new insights into their clinical behaviors. Aim:To compare the retentive abilities of two luting agents, using them to lute crowns on implant abutments of different diameters. Materials and methods:Two implants (3.7 and 6.0 mm diameter) were embedded in a resin block. Straight abutments of corresponding diameters were screwed into the implants. The height of abutments was kept equal for both abutments (8 mm). Seven copings were fabricated for each abutment. Groups 1 and 2 copings (14 copings) were tested for both luting agents; zinc phosphate and polymeric cement using a universal testing machine.Results: For the abutment diameters tested, the retentive values of zinc phosphate was significantly greater than polymeric implant cement. For the broad abutment, zinc phosphate was significantly more retentive than polymeric implant cement. For the narrow abutment, retentive values of zinc phosphate and polymeric implant cement were almost similar. Conclusion:The retentive values of zinc phosphate were significantly greater than polymeric implant cement. For broad abutment, zinc phosphate was more retentive whereas for narrow abutment, retentive values were almost similar.

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