Influence of Luting Materials on the Retention of Cemented Implant-Supported Crowns

The objectives of this study were to evaluate the retention force of cemented crowns on implant abutments with different luting materials. Cobalt-chromium crowns (n=128) were randomly divided into eight groups (n=16), and a standardized mixture was cemented onto tapered titanium abutments (Camlog) with the following types of luting materials: one eugenol-free temporary cement (RelyX TempBond NE, 3M Oral Care), one composite-based temporary cement (Bifix Temp, Voco) one zinc phosphate cement (Harvard Cement; Hoffmann), two glass-ionomer cements (Meron, Voco; Fuji I, GC), and three resin-modified glass-ionomer cements (Fuji 2, GC; Fuji Plus, GC; Ketac Cem Plus, 3M Oral Care). All specimens were aged for 14 days at 37°C in artificial saliva (S1). One half of the specimens from each group (n=8) were additionally thermocycled (5.000X, 5-55°C) (S2). Then, the crowns were vertically removed using a universal testing machine at a speed of 1 mm/min, and the force was recorded (measurement time T1). Afterwards, the crowns were recemented, aged, and removed and the force was recorded (T2, T3). A linear multiple regression analysis evaluated the influence of the luting materials and aging conditions (S1, S2) on the retention force and measurement times (T 1-3). The multiple linear regression analysis exhibited a statistically significant impact of luting materials and storage condition on the retention force. The retention forces differ statistically significant in the storage condition at T1 (p = 0.002) and T3 (p = 0.0002). The aging conditions (S1, S2) had a small significant influence (p < 0.05) at T3 that was not local. After aging, S1 Ketac Cem Plus had the highest retention force difference (T3 vs. T1) (-773 N) with respect to the median value, whereas RelyX TempBond NE had the smallest difference (-126 N). After aging, S2 Meron had the highest retention force difference (-783 N), whereas the RelyX TempBond NE had the smallest difference (-168 N). Recementation of implant-supported cobalt-chromium crowns decreases the retention force independent of the luting material. A material-specific ranking of the retention force of cemented implant-supported cobalt-chromium crowns was observed at T1.