Effects of three different types of intracoronal bleaching agents on shear bond strength of stainless steel and sapphire brackets bonded to endodontically treated teeth : an in vitro study

Abstract EN

Background : Evaluate the effects of three different intracoronal bleaching agents on the shear bond strengths (SBS) and failure site of stainless steel and monocrystalline (sapphire) orthodontic brackets bonded to endodontically treated teeth using light cured orthodontic adhesive in vitro.

Materials and methods : Eighty extracted sound human upper first premolars were selected, endondontically treated and randomly divided equally (according to the type of the brackets used) into two main groups (n = 40 per group).

Each main group were subdivided (according to the bleaching agent used) into four subgroups 10 teeth each ; as following : control (un bleached) group, hydrogen peroxide group (Hp) 35 %, carbamide peroxide group (CP) 37 % group and sodium perborate (SP) group .

The bleaching process was applied three times (4 days intervals) sequentially and the bleached teeth were stored in artificial saliva four weeks before bonding.

Orthodontic brackets were bonded with a light cure composite resin and cured with LED light.

After passing 24 hours of bonding procedure, the brackets were debonded by a Tinius-Olsen universal testing machine, to measure the shear bond strength.

After debonding, each bracket base and the corresponding tooth surface were examined using a stereomicroscope and their Adhesive Remnant Index (ARI) was recorded.

Results : The ANOVA test showed that the SBS of stainless brackets was significantly reduced by intracorornal bleaching agents.

Furthermore, LSD showed no significant difference in SBS between the three types of bleaching agents used in stainless steel group.

Whilst for sapphire group, the results The ANOVA test showed no significant difference in SBS between the bleached groups and the control group.

Chi-square comparison no significant difference in failure site between bleached and control groups in both brackets types used.

Conclusion : The effect of intracoronal bleaching on SBS was reduced SBS of stainless steel and not for sapphire.

However, the intracoronal bleaching had no effect on the failure site of orthodontic brackets used.