Comparison of shear bond strength of orthodontic buccal tube bonded to zirconia crown after using two different (10-mdp)-containing adhesive systems

Use of zirconia in cosmetic dentistry has expanded which coincided with a new trend of adult-orthodontics; therefore it is very important to find an accepted method and material of bonding orthodontic appliances-affectively to zirconia surface.

The sample was composed of 30 monolithic zirconia crowns-of the lower right first molar. All samples were treated first by sandblasting with aluminum oxide particle 50 μm, then they were divided into 3 equal groups (the 1^st group was the control, while 2^nd and 3^rd were the test groups), containing 10 crowns each, according to the type of adhesive system used; conventional light cure orthodontic bonding system (Transbond^TMXT Primer/ Transbond^TMXT composite resin) was used in the control group, while 2 different (10-MDP)-containing adhesive systems (Single Bond Universal adhesive/ Transbond TM XT composite resin, Thera Cem dual-cured self-adhesive resin cement) were used in the test groups, buccal tube of lower right first molar (Ortho-Cast M-Series, Dentaurum, Germany) was bonded on the buccal surface of each zirconia crown in all the groups using one of the adhesive systems.

The Single Bond Universal group had the highest mean value of shear bond strength (16.299 MPa), followed by Thera Cem group (15.373 Mpa), while the control group had the least value (5.337 ± 1.274Mpa); however, a highly significant difference in the shear bond strength was found between control and Single Bond Universal, and control and Thera Cem groups, while non-significant difference was found between Single Bond Universal and Thera Cem groups.

The two types of (10-MDP)-containing adhesive systems provide good value of shear bond strength for buccal tubes bonded to zirconia surface, however, Single Bond Universal adhesive/composite resin is the best.