Influence of Orthodontic Bracket Bonding Protocol on Zirconia Ceramics and Resulting Bond Strength, Adhesive Remnant, and Debonded-Polished Zirconia Surface Roughness

Objective: This study evaluated the effect of primer protocol for metal orthodontic brackets bonded to zirconia ceramic and resulting shear bond strength (SBS), adhesive remnant index (ARI), and debonded and polished zirconia surface roughness. Methods: Zirconia specimens were milled, glazed, embedded in acrylic resin and the target area microetched with aluminum oxide. Glazed and microetched representative specimens were evaluated with energy dispersive spectroscopy (EDS). Specimens were randomly assigned to primer protocol, enamel (TransbondTM Plus Self-Etching Primer) or zirconia (Assure® Plus), and primed according to manufacturer instructions. Metal orthodontic brackets were bonded to the primed surface with resin adhesive (Transbond XTTM) and light cured. To simulate intraoral conditions, all primer and bonding protocols took place in an environmental chamber set at 33±2°C and 75±5% humidity followed by a 24-hour dark cure at 37 C. Following SBS testing, an ARI value was assigned to debonded brackets. Residual adhesive was removed from the debonded zirconia specimens, the zirconia surface polished, and surface roughness measured using a profilometer. Scanning electron microscopy (SEM) was performed for qualitative evaluation of the zirconia surface. Results: Zirconia substructure exposure by aluminum oxide microetching was verified with EDS. A significantly lower (p<0.05) SBS was recorded for metal orthodontic brackets bonded with enamel primer (5.43±1.82 MPa) compared to zirconia primer (7.24±1.07 MPa). A significantly lower ARI value for metal orthodontic brackets bonded with enamel primer compared to the zirconia primer indicated failure at the zirconia-adhesive interface compared to the adhesive-bracket interface when bonding with enamel and zirconia primers, respectively. There was no significant difference in average surface roughness for debonded and polished zirconia when using an enamel or zirconia primer protocol. There was a 57.4% positive correlation between SBS and ARI results. All specimens exhibited grain lifting and shelving of debonded and polished zirconia specimens regardless of primer protocol. Conclusions: Metal orthodontic brackets bonded with a zirconia primer protocol demonstrated significantly higher SBS; however, the clinical significance may be negligible. Metal orthodontic brackets bonded to zirconia ceramics using an enamel or zirconia primer protocol may be returned to their original surface roughness with a proper adhesive removal and polishing protocol.

Name thesis:degree_name

M.S. (Master of Science)

Level thesis:degree_level

Masters

Discipline thesis:degree_discipline

Oral and Craniofacial Sciences (UMKC)

Grantor

University of Missouri--Kansas City

Author dc:creator

• Bergman, Kaylee Anne

Advisors dc:contributor.advisor

• Walker, Mary P.
• Wang, Yong

Handle dc:identifier.uri

https://hdl.handle.net/10355/70625

OAI identifier oai:identifier

oai:mospace.umsystem.edu:10355/70625