Degree of Streptococcus mutans Colonization on Common Restorative Materials Subjected to Wear Cycle.

Abstract

To investigate and compare the degree of Streptococcus mutans (SM) colonization before and after in vitro wear simulation on monolithic zirconia (MZ), lithium disilicate (LD), ceramo-metal (CM), and composite resin (CR) specimens. Sixteen circular discs (10 × 3 mm) were fabricated for each group (MZ, LD, CR, CM). Half of the samples from each group (n = 8) were subjected to a wear cycle (n = 32 in total). The wild-type SM bacteria was incubated, diluted, and cultured for growth on the specimens with polished (n = 32) and worn surfaces (n = 32). The number of bacteria was calculated from colony-forming units (CFU). ANOVA followed by Tukey honest significant difference test (α < .05) was used for statistics. SM adhesion on the polished surfaces of all the tested materials exhibited similar values (P = .215), with the number of SM being lowest for LD (21.87 ± 28.14) and highest for CM (90.62 ± 76.69). After the wear cycle, ANOVA indicated significant differences (P = .000) for the number of bacteria between pre- and postwear conditions of all groups. MZ (21,028 ± 1,507.98) and CM (13,025 ± 2,690.85) showed the highest and lowest numbers of SM colonies, respectively. According to t test, postwear SM adhesion to all materials (P = .000) was significantly higher. SM colonization on the worn surfaces of all the materials showed significant differences (P < .05), except for between LD and CR (P = .973). Polished surfaces of evaluated materials showed similar SM colonization, which emphasizes the importance of following the minimum requirements of the polishing/glazing procedures. SM colonization on the material surfaces significantly increased after wear. MZ and CM possessed the highest and lowest SM colonizations, respectively.