Universal Adhesive for Fixed Retainer Bonding: In Vitro Evaluation and Randomized Clinical Trial

Area of Science:

• Dental Materials Science
• Orthodontic Adhesion
• Biomaterials

Background:

• Traditional orthodontic bonding relies on specific primers like Transbond XT Primer.
• Evaluating universal adhesives for orthodontic applications is crucial for improving clinical outcomes.
• Scotchbond Universal offers versatility but its efficacy in total-etch mode for retainers needs assessment.

Purpose of the Study:

• To compare the efficacy of Scotchbond Universal (SB) in total-etch mode versus Transbond XT Primer (XT Primer) for bonding fixed orthodontic retainers.
• To evaluate both in vitro bond strength and clinical long-term debonding rates.

Main Methods:

• In vitro: Bovine incisors were bonded with XT Primer or SB, followed by shear bond strength (SBS) and adhesive remnant index (ARI) testing.
• In vivo: 100 patients received fixed canine-to-canine retainers bonded with either XT Primer or SB, with debonding monitored over two years.

Main Results:

• In vitro, no significant differences in SBS or ARI were found between the XT Primer and SB groups (mean SBS ~12 MPa).
• Clinically, the SB group exhibited a significantly lower retainer failure rate over the two-year period in both arches.
• Incisors showed a higher failure rate than canines, irrespective of the adhesive used.

Conclusions:

• Scotchbond Universal, when used in total-etch mode, is a potentially effective alternative to Transbond XT Primer for bonding orthodontic fixed retainers.
• The clinical performance suggests improved durability with Scotchbond Universal in this application.
• Further research may explore the specific mechanisms behind the reduced failure rates observed clinically.