Light-curing of orthodontic bracket adhesive by transillumination through dentine and enamel

Abstract

Bonding properties of light-curing adhesive cured by transillumination through the tooth were compared to those achieved by the conventional technique. The study analyzed the degree of cure (DC%), debonding force (DF) and adhesive remnant index (ARI) when light was transmitted through dental hard tissues.

Slices of dentin and enamel of 1 mm in thickness were combined with total thicknesses of 3 or 4 mm to simulate tooth structure without the pulp tissue. DC% with curing time of 20 s, 40 s and 60 s and irradiance power was measured for each group (n = 5). Brackets were bonded using transillumination on extracted incisors (n = 6) and premolars (n = 10), and DF was measured and ARI was scored.

No statistical difference was found in light transmission between the simulated samples and incisors (p > .05). Increasing the curing time from 40 s to 60 s enhanced the DC% only in premolars (p < .05). An adequate DF was achieved through transillumination both in incisors and premolars, but in premolars, the DC% remained low compared to conventionally cured brackets. Most of the bracket failures resulted from weak bracket-adhesive bond.

Keywords:

• Transillumination
• orthodontic bracket
• polymerization

Acknowledgements

We thank the staff of Turku Clinical Biomaterials Center and University of Turku for the helpful comments and help when needed.

Consent for publication

The authors obtained consent to publish.

Availability of data and materials

All data collected and analyzed for this study are included and presented in the published article.

Ethics approval

Extracted human third molars, incisors and premolars are received from the dental teaching clinic of University of Turku and personal information cannot be associated with the extracted teeth. By the Finnish Tissue law section 20, donated tissues can be used to research without consent of the ethics committee if personal information is not handled.

Additional information

Funding

The University of Turku and the Turku Clinical Biomaterials Center (TCBC) offered the working spaces, materials and the staff. No funding from the outside was collected.