ABSTRACT
Background: 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. Materials and methods: 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 1st group was the control, while 2nd and 3rd were the test groups), containing 10 crowns each, according to the type of adhesive system used; conventional light cure orthodontic bonding system (TransbondTM XT Primer/ TransbondTM XT composite resin) was used in the control group, while 2 different (10-MDP)-containing adhesive systems (Single Bond Universal adhesive/ TransbondTM XT composite resin, TheraCem 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. Results: The Single Bond Universal group had the highest mean value of shear bond strength (16.299 MPa), followed by TheraCem 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 TheraCem groups, while non-significant difference was found between Single Bond Universal and TheraCem groups. Conclusions: 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.
ABSTRACT
Patient’s soft tissue profile plays a prominent role in orthodontic diagnosis and treatment planning, many researchers have defined various facial soft tissue parameters based on lateral cephalometric radiographs by using either anatomic point method or tangent line method, however, these methods differ in the way of constructing straight lines along the soft tissue profile. This study aimed to compare the reliability of the two drawing methods (anatomic point and tangent line method). The sample consists of 100 true lateral cephalometric radiographs of patients with normal occlusion and accepted facial profile aged (18-30) years, ten angular measurements along the soft tissue contour were measured by the 2 drawing methods by 3 orthodontist examiners and analyzed statistically to fined means and standard deviation and to be compared by intra-class correlation coefficient. The results showed the non-significant difference between the measurements of the two drawing methods, and both methods were reliable and consistence in soft tissue profile analysis.