Abstract
ObjectiveTo investigate the effect of chlorhexidine applications in various forms and concentrations on adhesion and failure modes of metal brackets in vitro.Material and methodsNinety bovine enamel specimens were allocated to six groups (n=15). Metal brackets were bonded on all specimens after chlorhexidine pre-treatments forming the following groups: (1) untreated specimens (control); (2) 40% varnish (EC40, Biodent BV, Netherlands), remnants removed with brushing mimicking patient cleaning; (3) 40% varnish (EC40), remnants removed with brushing mimicking professional cleaning; (4) 1% varnish (Cervitec Plus, Ivoclar vivadent, Schaan, Liechtenstein), remnants not removed; (5) brushed with% 1 gel (Corsodyl, GlaxoSmithKline, Münchenbuchsee, Germany), remnants not removed; (6) immersed in 0.07% mouthrinse (Corsodyl, GlaxoSmithKline, Münchenbuchsee, Germany), remnant not rinsed. Debonding of brackets was performed using a universal testing machine. Data were analysed using one-way ANOVA and post-hoc Scheffé test.ResultsGroup 4 performed significantly inferior than all the other groups and the control. Group 4 presented the highest number of adhesive failures at the enamel-resin interface whereas in other groups no failures at adhesive-resin interface was observed.ConclusionPresence of chlorhexidine varnish prior to bracket bonding adversely affects adhesion. Concentration of chlorhexidine pre-treatment has no influence on shear bond strength.
Highlights
Standard caries prevention measures based on mechanical plaque removal, non-cariogenic dietary habits and regular fluoride supplementation are often insufficient to prevent new lesions in orthodontic patients [1]
Concentration of chlorhexidine pre-treatment has no influence on shear bond strength
CHX was tested in all three forms under following conditions: before acid etching without subsequent surface cleaning; after enamel etching mixed with bonding agent; after enamel etching alone, without additional bonding agent; after enamel etching prior to photo-polymerization of the bonding agent; after enamel etching following the photopolymerization of the bonding agent and mixed with bonding agent on hydrophilic primer applied etched enamel [10,11,12,13,14,15,16]
Summary
Standard caries prevention measures based on mechanical plaque removal, non-cariogenic dietary habits and regular fluoride supplementation are often insufficient to prevent new lesions in orthodontic patients [1]. No adverse effect was reported when CHX with low concentrations was applied prior to acid etching but controversial results were reported following applications after acid etching where only mixing CHX varnish with the bonding agent was agreed to be a safe application by the researchers [10,11]. Adhesion might get affected by the presence of CHX on the enamel surface depending on its form and concentration [10,16] To test this question, the aim of this present study was to investigate the influence of various pre-treatments with CHX applied according to manufacturer instructions on adhesion of brackets prior to bracket placement and observe the failure types following debonding. The hypothesis tested was that CHX pre-treatments that were removed from the surface prior to bonding procedures would have no adverse effect on the adhesion of metal brackets
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