engleski

Heating of GIC improve shear bond strength to enamel

Objectives: The aim of this in vitro study was to compare the influence of externally applied 'command set' methods (heat, ultrasound) on shear bond strength to enamel of several glass ionomer cements (GIC). Methods: The vestibular surfaces of 180 extracted molars were wet ground with a series of abrasive disks ending with 500 grit until a flat enamel surface was created. Three restorative GICs (GC Fuji IX GP Fast, GC, LOT 0605021 ; GC Fuji Triage, GC, LOT 0703051 ; VOCO Ionofil Molar AC, VOCO, LOT 712064) were cured in three ways: standard (SC), ultrasonic excitation (UC) and by an external heat source (HC). The teeth were randomly divided into three groups of sixty samples per each and were conditioned in two ways: 30 with 10% polyacrylic acid and 30 without conditionining. Each of those groups comprised ten samples treated in different ways: SC, UC or HC. The GIC were mixed and applied following the manufacturers' instructions and used to fill teflon moldes (3x4 mm). The samples were loaded in a Universal testing machine (Lrx Material Testing Machine, AMATEK Lloyd Instruments Ltd, UK) at a 1 mm/min crosshead speed. The surfaces at the fracture site were analyzed using stereomicroscope and SEM. The data were assessed by using three-way ANOVA. Results: The heat cured Fuji IX on conditioning enamel had significantly greater shear bond strength (13.3 MPa) than all other tested groups (p<0, 001). The mean shear bond strength in GIC with SC and without enamel conditioning was 3, 6-5MPa and had significantly lower bond strength. The bond strength of HC glass ionomers and conditioned enamel with 10% polyacrylic acid was significantly higher than all other tested groups. Conclusion: Heating of GIC increase bond strength, improves the properties of GIC restoration and can be recommended for use as a 'command set' method.

Shear bond strength; glass ionomer; heat curing; ultrasound curing

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