Daily exposure to fluoride mouthrinse produces sustained fluoride release from orthodontic adhesives in vitro

Objectives: To determine firstly, if sustained fluoride release can be achi eved from five orthodontic adhesives: Ketac-Cem, Fuji ORTHO LC, Sequence, T ransbond and Right-On, with daily exposure to fluoride mouthrinse in vitro, and secondly. if sustained fluoride release can be re-established from the same specimens, after an interruption in mouthrinse exposure. Methods: Ten brackets were bonded to bovine incisors using each adhesive. E ach adhesive group was divided equally into a test and a control sub-group. In phase 1 (42 days), the test sub-groups were exposed for I min daily to fluoride mouthrinse (225 ppm), followed by immersion in de-ionised water fo r 42 days to deplete their fluoride reserves. Mouthrinse exposure was then resumed in phase 2 (28 days). Mean cumulative fluoride release (MCFR) was c alculated for days 0-21 of phase 1 and for the plateau portion of the fluor ide release curves in phase 1 (days 21-42) and phase 2 (days 7-28). Results: During phase 1, the MCFR for each test sub-group was significantly greater than its control (p< 0.05). There was no significant difference in MCFR between the curve plateau portion of phases 1 and 2 for all adhesives except Transbond, for which MCFR was less in phase 2 (p< 0.05). Conclusions: Sustained fluoride release occurred for each adhesive exposed daily to fluoride mouthrinse, at a level significantly greater than its con trol. After fluoride exhaustion, re-exposure to daily fluoride mouthrinse p roduced sustained fluoride release levels comparable to those prior to exha ustion, for all adhesives except Transbond. (C) 2001 Elsevier Science Ltd. All rights reserved.