Effect of immediate and delayed finishing and polishing procedure on Streptococcal mutans adhesion and micro-hardness of composite resin surface: An in-vitro study

Abstract

Proper finishing and polishing have become the indispensable step in clinical restorative dentistry due to increased aesthetic demands. There are several polishing systems containing fine particle size abrasives. The adhesion of bacterial plaque to restoration depends on the surface properties and composition of materials. In literature, surface roughness after polishing is well documented, but the timing, i.e., immediate or delayed polishing affecting the bacterial adherence and microhardness on the composite needs research. As the Streptococcus mutans has a major role in primary and secondary caries, so in this light, this study is conducted to investigate the best timing of polishing affecting the bacterial adhesion and microhardness of composite resin.: To evaluate the Streptococcal mutans adhesion and microhardness of composite resin after polishing them, immediately and after 24 hours of curing.: Sixty specimens were made from composite resin Filtek Z 350 XT (3M ESPE) of 6mm diameter and 4mm height, was cured by placing a Mylar strip and divided into 3 groups- Group 1 the control group with only MYLAR-STRIP, Group 2- Polishing system SOF-LEX (3M ESPE Dental products St. Paul, MN,USA.) Group 3- Polishing with SUPER-SNAP (Shofu Inc., Kyoto, Japan). Group 2 and 3 were further divided into two subgroups according to the polishing time- immediate and delayed. The Streptococcal mutans adhesion for each group was measured by colony forming units and compared. The mean log of CFU/mL present in the biofilm was also calculated. The results of bacterial adherence was analysed by three-way ANOVA (analysis of variance) (p<0.01) and the ANOVA two-way of variance was used for checking microhardness (p<0.01). A p value <0.01 was considered to indicate a statistically significant for both bacterial adhesion and hardness. Polishing after 24 hours of curing showed less bacterial adherence on the composite surface, regardless of the polishing treatment performed(p<0.01). Polishing with SOF-LEX(Group-2) had the lower bacterial adherence than SUPER-SNAP (Group-3), Control group (Mylar matrix strip) promoted the lowest bacterial adhesion on the surface composites. Micro hardness of composite was lowest in Mylar matrix group. Immediate polishing procedure showed lower microhardness values as compared to polishing that was delayed for 24hours for both polishing groups. SOF-LEX system can be used for chairside polishing of composite restorations in clinic and delayed finishing and polishing of composite shows better surface microhardness values.