Introduction: Flowable resin composites have been recommended for many clinical uses and have been formulated in a variety of compositions and viscosities to meet various uses.
Aim of the work: To determine if flowable composite with or without primers could be used in orthodontic bracket bonding.
Materials and Methods: Sixty human premolars and sixty metal brackets were randomly and equally divided into four subgroups. 1A subgroup (TXT with primer), 1B subgroup
(TXT without primer), 2A (GF with primer) and 2B (GF without primer). After 72 hours, debonding was performed with a shearing force. The SBS (Shear Bond Strength) and the mode of bond failure were examined with ARI. Another twenty eight teeth were bonded by the same protocol to evaluate microleakage after thermocycling and dying with 2% methylene blue dye for 24 hours.
Results: Respective SBS results of the four subgroups were 14.6 ± 5.3, 13.3 ± 6.8, 18.9 ± 6.1 and 12.5 ± 5.9 MPa respectively. SBS value of subgroup 2A were significantly higher than subgroups 1A, 1B and 2B. After debonding ARI scores 0 and 1 were predominant in subgroups 1A, 1B and 2B, where subgroup 2A had ARI scores of 1 and 2. Subgroups 1B and 2B showed microleakage at both bracket-adhesive and enamel- adhesive interfaces, while subgroups 1A and 2A only 43% showed microleakage at bracket-adhesive interface.
Conclusions: Flowable composite (GF) can be successfully used for bonding orthodontic brackets as it provided SBS comparable with conventional composite (TXT), as well as can be used without primer as it gives a clinically acceptable SBS and favorable bond failure pattern. However, from microleakage point of view flowable composite (GF) with primer demonstrated the best performance.