Journal of Dental Medicine

Background and Aim: At the end of fixed orthodontic treatment, enamel damages are affected by amount of adhesive remnants. Thus, determining the factors involves in the amount of adhesive remnants e.g. the types of resins and the methods used for debonding is of necessity. The aim of this study was to evaluate the effect of the composite resin type and debonding pliers on enamel surface by a new method in measuring the adhesive remnant.

Materials and Methods: In this interventionally in-vitro study, 120 extracted human premolars were randomly divided into four groups of 30 each. The standard edgewise metal brackets were bonded on the teeth with two pastes self-cure composite "Concise" in the first and second groups, and with No-mix composite "Unite" in the third and fourth groups. the debonding was done by means of Lift off Debonding Instrument "LODI" (3M-Unitek), in first and third groups, and Bracket Removing Plier (Dentaurum), in the second and forth groups, respectively. After debonding, all teeth were evaluated with steriology software (stereolith version 1) for comparing the amount of adhesive remnants between the four groups. For data analysis, One-way ANOVA and independent t.test were used.

Results: The fourth group showed the lowest adhesive on the enamel surface and the most on the bracket surface with significant differences with other three groups (p<0.01).

Conclusion: The use of Dentaurum debonding plier with shear-peel force when used with the Unite adhesive (group 4), would decrease the adhesive remnants on the enamel surface.

Background and Aims: The bond strength between veneer ceramics and zirconia frameworks is the weakest component in the layered ceramics. Due to the possible effect of adding pigments to the core materials on the bond strength between core and veneer as well as the introduction of new ceramic materials in dentistry, the aim of this study was to compare the zirconia core-veneer microtensile bond strength using two ceramic veneers with or without coloring the core.
Materials and Methods: In this experimental study, 12 disc-shaped specimens were fabricated using a manually aided design- manually aided manufactured (MAD/MAM) zirconia core (Zirkonzahn). Two veneering ceramics of Ceram Kiss and Zirkonzahn ICE were also used to veneer the specimens. Half of the Zirkonzahn discs were remained white and the others were colored by shade A2.Then, the discs were cut into microbars (30 for each group) and the microtensile bond strength of the core-veneer was calculated. The specimens were assessed using scanning electron microscopy (SEM) and the data were analyzed using two-way ANOVA and Student's t-test.
Results: Significant differences with respect to veneer layer were found (P<0.001). No significant differences were seen among colored and uncolored cores (P=0.69).
Conclusion: According to the apparent effect of veneering ceramics on the core-veneer bond strength, careful selection of these agents is essential to achieve adequate bond strength between core and veneer to prevent delaminating and chipping failures of zirconia veneered restorations.