Effects of fluorosed enamel on orthodontic bracket bonding : An in vitro study.

Abstract

To investigate the effect of enamel deproteinization and air abrasion on shear bond strength (SBS), adhesive remnant index (ARI) scores, and surface topography when bonding orthodontic brackets to fluorosed enamel. The sample included 90fluorosed and 30normal premolars divided into four groups: groupI (fluorosed premolars subjected to air abrasion before acid etching), groupII (fluorosed premolars subjected to deproteinization before acid etching), groupIII (fluorosed premolars; control for groupsI andII), and groupIV (normal premolars; control for groupIII). Bonding procedures included etching with 37% phosphoric acid, priming with TransbondTM XT primer (3M Unitek, Monrovia, CA, USA), and application of TransbondTM XT adhesive paste (composite; 3M Unitek, Monrovia, CA, USA). Air abrasion was done using 50 µm aluminum oxide particles under 0.28 MPa pressure for 5 s with the micro-etcher held at adistance of 10 mm. Deproteinization was done for 60 s with 5% sodium hypochlorite (NaOCl). Fluorosed premolars subjected to deproteinization showed the lowest (median = 6.57 MPa) SBS among the four groups, followed by 8.14, 8.90, 8.14 MPa for groupsI, III, andIV respectively. ARI scores were significantly different between the four groups (p = 0.006). Fluorosed enamel etched after air abrasion or deproteinization with NaOCl showed apredominance of type4 etching pattern with some areas appearing unetched. Shear bond strength of all groups was within the 6-8 MPa acceptable range for orthodontic purposes. Fluorosed premolars subjected to deproteinization showed the lowest values. Further studies are recommended to scrutinize the deproteinization technique.