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 ¼ 5). Brackets were bonded
using transillumination on extracted incisors (n ¼ 6) and premolars (n ¼ 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.