Clinical study of the caries-preventive effect of resin-modified glass ionomer restorations: aging versus the influence of fluoride dentifrice.

AIM: The use of fluoride-releasing materials could be compromised due to aging and might also be influenced by other ordinary sources of fluoride. The aim of the present study was to investigate the aging effect on caries development around resin-modified glass ionomer cement (RMGIC) restorations and the influence of fluoride dentifrice use in this process under the oral environment. METHODS: A clinical study was performed in two phases of 14 days each. A total of 16 volunteers wore palatal devices containing dental slabs restored with either a composite resin or RMGIC, either aged or unaged by thermocycling. To simulate a clinical situation of high caries risk, the slabs were exposed to a 20% sucrose solution 10 times per day via the in situ model, where non-fluoride or a fluoride dentifrice was used. Integrated demineralization was determined by cross-sectional microhardness at both margins of the restoration: enamel and dentin. RESULTS: For enamel, higher demineralization around the composite restorations was observed, regardless of dentifrice or aging. For dentin, higher demineralization was observed around the aged composite restorations regardless of the dentifrice type used. CONCLUSIONS: The RMGIC restorations provided more enhanced protection against secondary caries for dentin under aging, and the fluoride dentifrice used in this condition had either no clinically relevance or only a minimal effect.

Push-out bond strength of a self-adhesive resin cement used as endodontic sealer.

OBJECTIVES: The aim of the present study was to investigate the bond strength of RelyX Unicem (3M) to root canal dentin when used as an endodontic sealer. MATERIALS AND METHODS: Samples of 24 single-rooted teeth were prepared with Gates Glidden drills and K3 files. After that, the roots were randomly assigned to three experimental groups (n = 8) according to the filling material, (1) AH Plus (Dentsply De Trey GmbH)/Gutta-Percha cone; (2) Epiphany SE (Pentron)/Resilon cone; (3) RelyX Unicem/Gutta-Percha cone. All roots were filled using a single cone technique associated to vertical condensation. After the filling procedures, each tooth was prepared for a push-out bond strenght test by cutting 1 mm-thick root slices. Loading was performed on a universal testing machine at a speed of 0.5 mm/min. One-way analysis of variance and Tukey test for multiple comparisons were used to compare the results among the experimental groups. RESULTS: Epiphany SE/Resilon showed significantly lower push-out bond strength than both AH Plus/Gutta-Percha and RelyX Unicem/Gutta-Percha (p < 0.05). There was no significant difference in bond strength between AH Plus/Gutta-Percha and RelyX Unicem/Gutta-Percha (p > 0.05). CONCLUSIONS: Under the present in vitro conditions, bond strength to root dentin promoted by RelyX Unicem was similar to AH Plus. Epiphany SE/Resilon resulted in lower bond strength values when compared to both materials.