Effect of powder/liquid ratio on the clinical and laboratory performance of resin-modified glass-ionomers.

OBJECTIVES: To compare the effects of powder/liquid (P/L) ratio and surface wetness on retention of adhesive Class V restorations. METHODS: One-hundred and six Fuji II LC restorations were placed at two clinical trial sites. In the 'high-dry group (Site A), Fuji II LC was mixed at a P/L ratio of 3.0 and applied to dentine that was visibly dry, but not desiccated. In the 'low-wet' group (Site B), Fuji II LC was mixed at a P/L ratio of 2.25 and applied to dentine that was glisteningly moist. The restorations were evaluated at baseline, 1 and 2 years at both sites, and at 3 years at one site. The P/L ratio effects on viscosity and wetting were evaluated in vitro by determining the film thickness possible at different ratios. RESULTS: At 2 years the retention levels at the two sites differed significantly (p < or = 0.1). Site B ('low-wet' group) exhibited 100% retention, and Site A ('high-dry' group) exhibited 78% retention. At 3 years Site A exhibited 74% retention, and nine of the 12 retention failures occurred in patients 65 years and older. Laboratory measurements demonstrated that the viscosity of 'low-wet' mixtures permitted film thickness that were one-half those of the 'high-dry' group. CONCLUSIONS: The study demonstrated that a higher powder/liquid ratio and a drier dentine surface compromised wetting by a resin-modified glass-ionomer resulting in a decline in retention from baseline to 3 years. This study suggests that the dentine surface should be kept hydrated to promote bonding, and that the powder/liquid ratio should be low enough to create low-viscosity mixtures which promote wetting. In the 'high-dry' dentine group there was still 74% retention at 3 years, indicating that factors other than wetting affect retention.

Restoration of Class V abrasions with a new light-cured glass ionomer restorative.

The clinical performance of conventional glass ionomer materials have demonstrated clinical success in Class V restorations, but the physical properties and limited aesthetics of these materials have limited their widespread utilization. This article describes the clinical application of a new Type II light-cured glass ionomer restorative material, demonstrating improved physical properties and aesthetics.

Rotary instrument finishing of microfilled and small-particle hybrid composite resins.

Tungsten carbide burs operated at high speeds for trimming and finishing microfilled composite resins are contraindicated as they disrupt the composite resin surface. Diamond burs operated at low speeds do not disrupt the surface on microfilled and small-particle hybrid composite resins. High-speed finishing with carbide burs on small-particle (hybrid) composite resins produces not only a nondisrupted surface but leaves the surface flat and smooth--free from the characteristic striations and grooves left by diamond burs. These results suggest that the rotary instruments used to finish a composite resin must be selected in accordance with the type of composite resins used.