Esthetic dental restorations have gained increasing popularity in the recent years. Although such treatments can meet patient satisfaction in short-term, the important point is to ensure their long-term durability and quality (11).
Poorly finished and polished restoration surfaces can enhance the accumulation of bacterial plaque and calculus and lead to subsequent complications (12). Airflow or air-polishing systems have recently gained popularity for mechanical stain removal. These systems spray compressed air with some powders on the surface to eliminate stains (8). This study assessed the effect of Prophy-Mate Neo airflow device on surface roughness and its efficacy for stain removal from the composite surface. Calcium carbonate and sodium bicarbonate powders can be used in this device. Calcium carbonate particles are spherical and minimize surface traumatization by rolling on the surface. Sodium bicarbonate powder, which is currently less commonly used, has cubic particles. Controversy exists regarding the positioning of cubic particles on the surface (24, 25).
Two other commonly used polishing methods in the clinical setting were also assessed in this study namely the use of diamond paste and buff, and FlexiDisc composite finishing and polishing discs. According to Yurdaguven et al, (11) the Diamond Excel paste applied with a buff disc can yield a lower surface roughness in the enamel than other polishing pastes. Also, Camboni and Donnet found no significant difference in enamel surface roughness following the use of airflow device and diamond paste (10). Berger et al. (23) showed that FlexiDisc finishing and polishing discs yielded a lower surface roughness than other composite polishing methods, and therefore, were used in this study.
Assessment of the Ra surface roughness parameter revealed a significant change in surface roughness after using airflow with calcium carbonate, compared with the baseline surface roughness of composite specimens (P = 0.019), that indicated the more successful performance of calcium carbonate in reduction of surface roughness, which was in agreement with the results of Graumann et al, in 2013 (26). Superior performance of calcium carbonate powder may be due to the spherical shape of its particles, which can more easily roll on the surface than cubic sodium bicarbonate particles. Also, spherical particles have smaller contact area with the surface and consequently less friction while both spherical and cubic particles of the two powders are of the same size.
Comparison of different composite polishing techniques namely airflow polishing with calcium carbonate, airflow polishing with sodium bicarbonate, and FlexiDisc regarding the resultant surface roughness revealed that airflow with sodium bicarbonate had significant differences with airflow with calcium carbonate and FlexiDisc, which could be attributed to the poor performance of sodium bicarbonate powder. Similarly, Barnes et al. (27) discussed that sodium bicarbonate powder yielded higher surface roughness than calcium carbonate and glycine powders. Sulieman et al, (14) in a systematic review discussed that the acceptable surface roughness to obtain a durable and shiny surface was 0.2 µm. In this study, the surface roughness of composite specimens subjected to calcium carbonate (0.251 µm) and FlexiDisc polishing kit (0.207 µm) was close to this value. The difference in surface roughness of enamel (0.381 µm for specimens subjected to calcium carbonate powder and 0.447 µm for specimens subjected to sodium bicarbonate) and composite (0.421 µm in sodium bicarbonate group) can question the efficacy and application of this particular device, compared with other devices and polishing systems, after taking into account its cost and availability.
Also, a significant difference in surface roughness was noted in composite specimens subjected to FlexiDisc polishing system compared with baseline (P = 0.01). Similarly, Berger et al. (23) reported that application of FlexiDisc and Sof-Lex discs for polishing significantly changed the surface roughness of specimens compared with baseline. However, the mean surface roughness value of composite in our study (0.207 µm in FlexiDisc group) was higher than the value reported by Berger et al (0.116 µm) (23), which can be due to the different composite types used in the two studies.
Color change of specimens at different time points was determined by calculation of ∆E. The ∆E > 3.5 is often considered as clinically detectable color change (22). Accordingly, at T1 and T2 following the use of airflow, 93% of specimens showed discoloration, which indicates successful performance of airflow with both calcium carbonate and sodium bicarbonate powders for stain removal. This finding was in agreement with the results of Graumann et al, in 2013 regarding the successful results of air-polishing for stain removal (26).
The relationship of change in surface roughness and color change of specimens was also evaluated in this study. In general, a positive correlation was noted between smoothing of surface and lighter color (L*), which is probably due to the more regular reflection of light due to lower surface porosities. Joiner et al, in 2006 (25) also reported a positive correlation between surface smoothness and increase in L* parameter. However, this correlation was only significant for the L* and ∆E of composite specimens subjected to calcium carbonate (P = 0.03).
Evaluation of surface roughness and color parameters in the polishing groups using airflow device (Prophy-Mate Neo) revealed successful performance of this device in combination with calcium carbonate powder for composite specimens. Similarly, Graumann et al, in 2013 (26) confirmed successful performance of calcium carbonate powder for this purpose. However, the cost, maintenance and safety of this device should also be taken into account, which was out of the scope of this study. The conventional clinical methods can also be used with optimal clinical efficacy.