COMPARATIVE STUDY REGARDING THE EFFECT OF DIFFERENT FINISHING AND POLISHING SYSTEMS ON A BULK-FILL COMPOSITE RESIN SURFACE
Figure 2. Mean values of Ra parameter of Filtek Bulk Fill in control group and after finishing and polishing.
Figure 3. Mean values of Rz parameter of Filtek Bulk Fill in control group and after finishing and polishing.
Table 2. The Kolmogorov-Smirnov normality test result.
Table 3. ANOVA statistical test result. larger particles of silica and zirconia. The appearance of the surface seems compact, revealing a close adhesion between the organic matrix and the inorganic load. For group 2 – Fig. 1b), the microstructure presents many parallel micro-channels 1 micrometer wide and a 10 micrometers mean distances between them. It is observed that the very fine particles on the surface and matrix elements were removed by abrasion, leaving large clusters with the diameter up to 5 µ m to be visible. Similar aspects are also observed in group 3 – Fig. 1c), but the micro-channels formed appear more accentuated and closer when compared to group 2. In group 4, the analyzed surface microstructure – Fig. 1d) indicates similar aspects, but the micro-channels are finer and rarer when compared to the samples from previous groups. The mean Ra and Rz values obtained by quantitative assessment of samples surface using profilometry are represented in Fig. 2 and Fig. 3, respectively. The lowest Ra( 0.023 µ m) and Rz( 0.181 µ m) values were obtained in group 1. In group 2, increased Ra and Rz values were found( Ra mean value of 0.211 µ m and mean Rz value of 1.308 µ m). In group 3 the same increase in the Ra and Rz mean values was observed( Ra of 0.229 µ m and Rz of 1.448 µ m). In group 4 the mean Ra( 0.098 µ m) and Rz( 0.798 µ m) values were much lower when compared to groups 2 and 3, but higher than the control samples. The result of the Kolmogorov-Smirnov normality test showed that in all groups the data were normal distributed( p = 0.250 > 0.05)( Table 2). In order to compare the results in groups, ANOVA and Tukey post hoc statistical tests were used( Table 3 and 4, respectively). Significant results were obtained when comparing Ra values in groups 2, 3, and 4 to group 1( p < 0.05, Table 4). Also, statistically significant results were obtained when comparing the surface roughness in group 2 to group 4 and in group 3 to group 4. The results in group 2 were not statistically significant when compared to group 3( p > 0.05, Table 4).
Original Article
Table 4. Tukey post hoc statistical test result.
rather than from the polymerization shrinkage. At this magnification, the surface of control samples appears to be much smoother compared to the other samples. At larger magnifications( 2000 ×) very small particles can be identified, not aggregated, distributed among
4. Discussion The type of inorganic filler of the material can influence the handling characteristic and the final surface aspect after finishing and polishing procedure. Some in vitro studies revealed that a number of other factors may influence the surface condition of the material, such as the type of finishing and polishing system: in one step or several steps [ 9,10 ]. It is a lack of consensual opinion in the literature regarding the effect of one step or multi-steps polishing system on composite resins surface roughness. It has been demonstrated that multi-step systems determined smoother surfaces than two-step systems or one-step systems [ 11 ]. On the other hand, some other studies showed that there are no significant differences between one-step and multi-step systems [ 12 ]. In the present study, the surface roughness of control samples was lower when compared to the results obtained for each of the three finishing and polishing systems used. These results are in agreement with a series of studies which have shown that the smoothest composite resin surface is obtained when the material is light-cured in tight contact with a celluloid matrix [ 13- 15 ]. The superficial layer, polymerized in contact with
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