Effect of tube debonding on the enamel surface in vitro : Evaluation with optical coherence tomography

In vitro evaluation of the morphology of the enamel surface before bonding metal tubes and after debonding using spectral domain optical coherence tomography (SD-OCT) and light microscopy.

In all, 40 extracted caries-free human molars without defects were selected and cleaned. The tooth surfaces were imaged by light microscopy and SD-OCT prior to the placement of metal tubes (Titanium Orthos; Ormco, Brea, CA, USA). The metal tubes were bonded to the teeth using four adhesive systems: group 1) BrackFix Primer SE with BrackFix adhesive, group 2) BrackFix Primer with BrackFix adhesive (VOCO, Cuxhaven, Germany), group 3) Transbond Plus SE Primer with Transbond XT adhesive, group 4) Transbond XT Primer with Transbond XT adhesive (reference, 3M Deutschland, Neuss, Germany). After tube removal, the bonded areas were imaged by light microscopy and/or OCT and evaluated according to the following four criteria: (1) depth of cohesive enamel defect, (2) enamel cracks, (3) adhesive residue after tube removal, and (4) adhesive residues after polishing.

None of the groups had enamel defects or enamel cracks. Group 1 showed significantly less adhesive residue after tube removal than the other groups (p_i ≤ 0.014). There were no significant differences between the groups for adhesive residues after polishing (p_i ≥ 0.628). Adhesive residues, if present, were only detectable by OCT and covered less than 1% of the enamel surfaces evaluated.

Tube removal did not cause clinically relevant enamel damage such as chipping or cracking.