The influence of dentin and/or metal surface treatment on the retention of cemented crowns in teeth with an increased taper

Objectives To evaluate the effect of dentin and/or metal surface treatments on retention of cast crowns cemented to preparations with compromised retention. Methods Cast crowns (n = 105) were fabricated on extracted molars prepared to 40° convergence and standard height. 60 teeth were randomly divided into: (A) cemented with zinc phosphate cement; (B–D) cemented with resin cement (Compolute, 3M) with either no surface treatment (B), dentin etched and bonded (EBS multi, 3M) (C), or dentin etched and bonded, and metal tribochemically treated (Co-Jet, 3M) (D); 45 teeth were randomly divided and crowns cemented with another resin cement (Rely-X Arc, 3M) with either no surface treatment (E), dentin etched and bonded (Single Bond, 3M) (F), or dentin etched and bonded and metal tribochemically treated (G). Teeth were stored in 100% humidity for 3 months and thermocycled 5000 cycles. Crowns were dislodged from the preparations and retention (MPa) was calculated. Results Group D showed significantly higher retention (3.52 ± 1.3 MPa) compared to Group C (2.26 ± 0.9 MPa), Group B (0.85 ± 0.4 MPa), and Group A (1.22 ± 0.4 MPa). Group G exhibited significantly higher retention (5.4 ± 1.4 MPa) compared to F (2.6 ± 1.2 MPa) and E (2.0 ± 0.6 MPa). Higher retention corresponded with more cohesive cement type of failure. Significance Cast crowns with compromised retention cemented by resin cement should undergo combined tribochemical metal treatment and dentin bonding. The crucial link is the interaction of different brands of resin cements with the metal tribochemically treated.