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

Erika Mäkinen; Lippo Lassila; Juha Varrela; Pekka Vallittu

doi:10.1080/26415275.2019.1632709

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

Biomater Investig Dent. 2019 Jun 24;6(1):6-12. doi: 10.1080/26415275.2019.1632709. eCollection 2019.

Authors

Erika Mäkinen¹, Lippo Lassila², Juha Varrela^{3

4}, Pekka Vallittu^{2

4

5}

Affiliations

¹ Institute of Dentistry, University of Turku, Turku, Finland.
² Turku Clinical Biomaterials Centre - TCBC, University of Turku, Turku, Finland.
³ Department of Oral Development and Orthodontics, University of Turku, Turku, Finland.
⁴ Welfare Division, University of Turku, Turku, Finland.
⁵ Department of Biomaterials Science, University of Turku, Turku, Finland.

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.

Grants and 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.