Polymerization with the argon laser: curing time and shear bond strength.

Area of Science:

• Orthodontics
• Dental Materials Science
• Biomaterials Engineering

Background:

• Traditional light-curing methods for orthodontic adhesives require significant time.
• Optimizing polymerization efficiency is crucial for reliable bracket bonding.
• Alternative curing technologies, like lasers, warrant investigation for improved clinical workflows.

Purpose of the Study:

• To evaluate the efficacy of an argon laser in polymerizing orthodontic adhesives.
• To compare argon laser curing parameters with conventional light-curing protocols.
• To assess bond strength and failure modes associated with different curing methods.

Main Methods:

• Metal brackets were bonded to 185 premolars using a light-cured orthodontic adhesive.
• Groups were subjected to different curing protocols: 40-second light (buccal/lingual) and 5-, 10-, or 15-second argon laser (lingual).
• Bonded specimens underwent aging (30 days water immersion, 24-hour thermal cycling) before shear-peel bond strength testing and failure analysis.

Main Results:

• Argon laser groups (5, 10, 15 seconds) showed mean shear-peel bond strengths (10.86-11.32 MPa) comparable to 40-second light-cured lingual groups (11.95 MPa).
• No statistically significant difference in bond strength was found between 40-second light-cured lingual and 5-second laser-cured lingual groups.
• A 5-second argon laser cure yielded bond failure loads similar to 40-second light cure, with a notably lower incidence of enamel fracture at debond.

Conclusions:

• Argon laser polymerization is an efficient alternative for orthodontic adhesives, achieving comparable bond strength to conventional light curing.
• Shorter intraoral application times are feasible with argon laser curing, potentially improving clinical efficiency.
• The use of argon laser may reduce the risk of enamel damage during bracket debonding.