The effect of mechanical load cycling and polishing time on microleakage of class V glass-ionomer and composite restorations:A scanning electron microscopy evaluation

Abstract

Background: Microleakage is one of the challenging concerns in direct fi lling restorations. Understanding

of its related factors is important in clinical practice. The aim of this study was scanning electron

microscopy (SEM) evaluation of marginal integrity in three types of tooth-colored restorative materials

in class V cavity preparations and the effect of load cycling and polishing time on the microleakage.

Materials and Methods: In this in vitro experimental study, class V cavity preparations were

prepared on the buccal and lingual surfaces of 60 bovine incisors. The specimens were divided into

three groups each containing 20 teeth: group 1: Filtek Z350, Group 2: Fuji IX/G Coat Plus, Group 3:

Fuji II LC/GC varnish. In each group, 2 subgroups (n = 20) were established based on fi nishing time

(immediate or delayed by 24 h). All specimens were thermocycled (×2,000, 5-50°C). In each sub

groups, half of the teeth were load cycled. Epoxy resin replicas of 24 specimens were evaluated

under fi eld emission-SEM and interfacial gaps were measured. All teeth were then immersed in 0.5%

basic fuchsin dye for 24 h, sectioned and observed under stereomicroscope. Data were analyzed

with Kruskal-Wallis’ test and Mann-Whitney U test and a comparison between incisal and cervical

microleakage was made with Wilcoxon test. P < 0.05 was considered as signifi cant.

Results: Load cycling and fi lling material had a signifi cant effect on microleakage, but polishing time did not.

Cervical microleakage in Z350/load cycle/immediate polish and Fuji IX/load cycle/immediate or delayed

polish and Fuji IX/no load cycle/immediate polish were signifi cantly higher than incisal microleakage.

Conclusion: It was concluded that the cervical sealing ability of Fuji IX under load cycling was

better than Fuji II LC. Under load cycling and immediate polishing Z350 showed better marginal

integrity than both Fuji II LC and Fuji IX. The immediate polishing didn’t cause a statistically signifi cant

increase in microleakage of evaluated tooth-colored class V restorations.

Key Words: Composite resins, dental leakage, dental polishing, glass ionomer cements