Effects of Different Stain Removal Protocols on Bonding Orthodontic Brackets to Enamel

To evaluate the effect of different stain removal protocols with or without topical fluoride application on the bond strength of orthodontic brackets to enamel.

Eighty extracted premolars were randomly assigned into four groups according to the stain removal protocol. The stain removal protocols were (1) using rubber cup with prophylaxis paste in (G1, n = 20), (2) air-abrasion with prophy-jet polishing system (G2, n = 20), (3) micro-abrasion with opalusture polishing paste (G3, n = 20), and (4) macro-abrasion with ultrafine diamond finishing tips (G4, n = 20). Ten teeth in each group (SG1, n = 10) had no topical fluoride treatment after stain removal protocol, while the rest (SG2, n = 10) were subjected to topical fluoride application. After bonding the orthodontic brackets, all specimens were thermocycled before testing their bracket-enamel bond strength. The debonded bracket and enamel surfaces of each specimen were also assessed to determine the adhesive remnant index (ARI) for each subgroup.

Specimens in G2, G3, and G4 recorded lower shear bond strength as compared with G1 (p < 0.05). For all groups, specimens in SG2 demonstrated lower bond strength than their counterpart in SG1 (p < 0.05). No significant differences were detected between the ARIs of different subgroups (p > 0.05).

Bonding orthodontic brackets is affected by the protocol of removing enamel stains. The use of the rubber cup with prophylaxis paste provided the highest bracket-enamel bond strength. Topical fluoride application usually complicates the bonding process of orthodontic brackets to cleaned enamel surfaces.

The results of the current study indicate higher bracket bond strength to enamel surfaces treated with different stain removal protocols than the clinically acceptable values (5.9-7.8 MPa). However, the more aggressive enamel pretreatment methods should not be considered unless the clinical situation necessitates such action. Postponing the topical fluoride application is advisable to follow the bracket bonding procedure. This action would prevent the negative effect of topical fluorides on bracket-enamel bond strength.