Effect of surface characteristic of different restorative materials containing glass ionomer on Streptococcus mutans biofilm.

AIM: The aims of this study were to evaluate the surface morphology and surface roughness of restorative materials containing glass ionomer, analyze Streptococcus mutans biofilm formation on the surface of materials, and determine the correlation between surface roughness and biofilm. MATERIALS AND METHODS: Four restorative materials: resin-modified glass ionomer; giomer; amalgomer; and glass carbomer were used and for each material, 6 mm in diameter and 2 mm in thickness disc-shaped specimens were prepared to evaluate the surface morphology (n = 3), surface roughness (n = 16), and biofilm (n = 20). Surface morphology was analyzed with a scanning electron microscope. Surface roughness was evaluated via an atomic force microscope. The biofilm was evaluated by counting the colony-forming units. Surface roughness measurements were evaluated using a one-way analysis of variance and Tukey HSD test. Biofilm parameters were analyzed using the Kruskal-Wallis H and Mann-Whitney U test. Pearson's correlation test was used to determine the correlation between surface roughness and biofilm. RESULTS: While the highest roughness values were obtained for amalgomer and glass carbomer, the lowest roughness values belonged to giomer and resin-modified glass ionomer. Statistically significant differences in the number of adherent bacteria were observed between the materials only on day 1. No statistically significant correlation was determined between surface roughness and biofilm. CONCLUSIONS: The resin content and small filler particle size of material positively affect surface roughness. However, there is no direct relationship between surface roughness and biofilm.

Comparative evaluation of marginal adaptation and microleakage of low-shrinking composites after thermocycling and mechanical loading.

AIMS: The aim of this study was to evaluate and correlate marginal adaptation and microleakage of different low-shrinking composites. MATERIALS AND METHODS: Standardized class V cavities (n = 20/group) with occlusal margin in enamel and gingival margin in dentin were restored with low-shrinking silorane-based (Filtek Silorane) or methacrylate-based (Clearfil Majesty Posterior, Grandio, Reflexions XLS, Tetric EvoCeram, Premise, Ceram-X Duo, Aelite LS Posterior) composites and a conventional composite (Filtek Z250). All teeth were stored in water (24 h), thermocycled (5000×), and mechanically loaded (60,000×). Marginal adaptation of epoxy resin replicas was analyzed using scanning electron microscope. Microleakage of the restoration was assessed by dye penetration on sectioned specimens under stereomicroscopy. Data were statistically analyzed with Mann-Whitney U test, with a significance of P < 0.05. Pearson's correlation test was used to evaluate the correlation between results of margin analysis and microleakage. RESULTS: No statistical difference in marginal gap formation was determined between Filtek Silorane and Z250. The lowest microleakage score at dentin margins was recorded for Filtek Silorane, which was not significantly different from that of all other groups. No similar ranking between the results of microleakage at enamel and dentin margins was observed for the materials tested. Marginal adaptation was not correlated to microleakage, except for Filtek Silorane, Grandio, and Filtek Z250. CONCLUSIONS: Compared to the conventional composite Filtek Z250, Filtek Silorane demonstrated no improvements with reduced marginal gap formation. Low-shrinking properties of composites appear to have no ability of sealing restoration margins and preventing leakage.