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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