Effect of Polishing Techniques and Time on Surface Roughness, Hardness and Microleakage of Resin Composite Restorations

Abstract

This study evaluated the effects of immediate and delayed polishing on the surface roughness, microhardness and microleakage of a microfilled (Filtek A110) and a hybrid (Filtek Z250) resin composite. Standardized preparations were made on the buccal surfaces of 256 bovine teeth; half were restored with each composite (128 teeth per composite). Immediately after curing, gross finishing was carried out with #280 sandpaper. The specimens restored with each composite were divided into two subgroups. The first group (IM) was polished immediately after gross finishing, using three different systems (n=16): Sequence A, Sof-Lex; Sequence B, Flexicups and Sequence C, Flexicups + Jiffy Polishing Brush + Flexibuffs. The specimens were then stored for three weeks in saline 37 degrees C. The second group (DE) was stored for two weeks, then polished with the same systems and stored for one additional week. The controls (n=16) were analyzed without polishing. Five readings per specimen were taken for surface roughness and hardness. After immersion in basic fuchsin, microleakage was evaluated (40x) using standardized scores. The data were analyzed at a significance level of 0.05, with analysis of variance and an SNK test (surface roughness and microhardness) or with Kruskal-Wallis (microleakage). In both composites, only for the sequential technique was there an influence of delay in polishing on roughness (Ra). Flexicups exhibited the highest Ra of the three systems. The IM and Filtek Z-250 groups showed higher hardness than the DE and Filtek A-110 groups, respectively. Dentin margins showed more leakage than enamel margins; the sequential technique produced more leakage than the other techniques in dentin (p<0.05) and delay of polishing was not significant in the majority of situations. In conclusion, several conditions--composite, time and polishing technique--had a significant influence on surface roughness, hardness and microleakage. Generally, immediate polishing produced no detrimental effect compared to delayed polishing.

The Effect of Polishing Techniques and Time on the Surface Characteristics and Sealing Ability of Resin Composite Restorations After One-year Storage

“…In this study, finishing was carried out with standardized 280-grit silicon carbide paper under running water to simulate the texture of a fine diamond bur, therefore producing specimens with similar surface characteristics before applying the tested polishing procedures/conditions. 15 Several studies agree that flexible aluminum-oxide disks are the best choice for providing the lowest roughness on composite surfaces. [32][33][34] Their efficacy, however, depends on the anatomical form and accessibility of the restoration surface to be polished.…”

“…Results from both the positive and negative controls are presented and discussed elsewhere. 15 Subsequently, all restored and finished specimens were randomly divided into 12 groups of 16 teeth and polished with: A) aluminumoxide discs-Sof-Lex Pop On XT (3M ESPE); B) rubber-polishing cups-Flexicups (Cosmedent, Chicago, IL, USA) and C) the sequential use of rubber-polishing cups, a polishing brush-Jiffy Polishing Brush (Ultradent, South Jordan, UT, USA) and felt-polishing discs-Flexibuffs (Cosmedent). The materials were used according to manufacturers' directions.…”

“…All the specimens underwent surface roughness evaluation, but just half were assessed regarding hardness and microleakage evaluations (n=8), and these results were previously presented and discussed. 15 Eight samples of each group were stored in saline at 37°C (solution replaced twice a week) to promote oneyear aging and evaluated under the same conditions and methods used at the baseline evaluations.…”

“…[11][12][13] The polishing ability of composites varies depending on particle size. 14 Although microfilled composites are more easily polished than hybrid composites, 11,15 it is believed that hybrid composites may provide the best properties and clinical performance for both anterior and posterior restorations. [16][17] The development of an optimal surface polish means a reduction in stain and plaque accumulation, minimization of wear effects and an enhancement in the definitive restoration's appearance.…”

“…[19][20][21][22] This means that the proper finishing and polishing of dental restoratives are critical clinical procedures that are not only for esthetics and longevity of restorations, but also for oral health. 23 Different methods can be used for restorations' finishing and polishing; 21 however, there is a lack of consensus as to which material and technique provides the smoothest surfaces for composites, 15,[24][25] and little research has been conducted on the influence of delay in polishing on surface roughness, hardness and the marginal sealing of composite restorations. 15,[26][27][28] Still, there are no publications that address the effect of aging processes or long-term storage related to these properties.…”