Effect of Bonding and Re‐Bonding on the Shear Bond Strength of Two‐Piece Implant Restorations

Abstract

Purpose

To evaluate the re‐bonding strength of ceramics to titanium alloy after disassembling by heat treatment.

Materials and Methods

A total of 40 titanium alloy (titanium‐6 aluminum‐4 vanadium) disks (4.0 × 6.6 mm) and 20 zirconia (Lava Plus) disks were manufactured using computer‐aided design and computer‐aided manufacturing (CAD/CAM) technology. Twenty heat‐pressed lithium disilicate glass‐ceramic (IPS e.max Press LT) disks were fabricated and used as controls. Bonding protocol for each specimen surface was performed according to manufacturer's instructions. Specimens (n = 10) of zirconia/titanium alloy (ZR) and lithium disilicate/titanium alloy (LD) were bonded using adhesive resin cement (RelyX Ultimate) and then subjected to a heat treatment (HT, 320°C, 2 minutes) to disassemble the bonding complex, cleaned with aluminum oxide airborne‐particle abrasion, and re‐bonded following the initial protocol, group ZRHT and group LDHT, respectively. After 5000 cycles of thermal cycling, a shear bond test was conducted. A universal testing machine was used at a 5 mm/min crosshead speed. Failed specimens were examined with stereomicroscopy at 10 × magnification to identify the mode of failure. One‐way ANOVA and Tukey HSD tests were applied for statistical analysis of the shear bond strength data, with statistical significance at α = 0.05.

Results

The mean ± SD bond strength values ranged from 28.3 ± 7.2 MPa to 45.9 ± 9.7 MPa. Statistically significant lower shear bond strength values were obtained from the group LD group (p = 0.002, F = 5.89), while no statistically significant differences in bond strength were observed between the ZR and ZRHT groups (p > 0.05). Failure mode was predominantly mixed‐type failure pattern for all specimens.

Conclusions

Heat and abrasion surface treatment increased the bond strength of lithium disilicate glass‐ceramics cemented to titanium alloy, but no effect was observed on zirconia/titanium alloy bonding.

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