Effects of two adhesion boosters on depth of penetration of orthodontic adhesive on fluorosed and normal enamel: A confocal microscopic study

Objectives: This study has been conducted to unveil adhesion promoter's underlying microscopic mechanism using confocal microscope. Materials and Methods: Fifty maxillary first premolars (25 fluorosed and 25 nonfluorosed) were selected. The teeth were divided into 4 groups of 10 teeth each based on the adhesion booster applied and two control groups of 5 fluorosed and 5 nonfluorosed teeth without adhesion booster. Two different adhesion boosters, All-Bond 3 (Bisco, Schaumburg, IL, USA) and Enhance LC (Reliance, Itasca, IL, USA), were mixed with Rhodamine B fluorescent dye and applied on the tooth to facilitate the detection of resin tags in the confocal microscope. The teeth were sliced to a cross-section of 800 μm by hard tissue microtome. Each cross section was scanned in confocal microscope till three distinct resin tags were seen, and this image was stored and quantified. The depth of penetration of adhesive resin tag was chosen as a measure of micromechanical bonding. Data obtained were statistically analyzed. Results: The maximum depth of penetration was recorded in fluorosed/All-Bond 3 group of 75.57 μm and a minimum depth of penetration was in fluorosed and conventional primer group of 26.46 μm. Conclusions: This shows that micromechanical bonding is compromised in fluorosed teeth. Both the adhesion boosters, All-Bond 3 and Enhance LC, enhanced the depth of resin penetration in fluorosed as well as nonfluorosed teeth while conventional primer did not prove to be very useful. Thus, adhesion boosters have been beneficial to increase the micromechanical bonding in cases where bonding is compromised, thus providing a good solution to effective orthodontic bonding.