Addition of nisin to high-viscosity glass-ionomer cement: a comparative in vitro study on antibacterial and physical properties.

PURPOSE: Nisin is a lantibiotic effective against Gram-positive microorganisms such as Streptococcus mutans. The study aimed to determine the effect of the addition of nisin to high-viscosity glass-ionomer cement (HVGIC) on its antibacterial activity, setting time, surface microhardness, and compressive strength. METHODS: 1 and 3% w/w nisin were added to HVGIC before mixing. Unmodified HVGIC was the control. Agar disc diffusion, direct contact test, and scanning electron microscopy (SEM) analysis were used to evaluate antibacterial activity against S. mutans. Setting time, surface microhardness, and compressive strength were measured using Gilmore needle apparatus, digital microhardness tester, and universal testing machine, respectively. Statistical analysis included Student's t test, one-way ANOVA with Tamhane's post hoc test, and repeated-measures ANOVA. RESULTS: As evidenced by the agar disc diffusion (p < 0.001), direct contact tests (p = 0.025), and SEM analysis of the S. mutans cell count and cell surface area (p = 0.049 and 0.003), 3% nisin had the strongest antibacterial activity. There was a dose-dependent increase in setting time (p = 0.005) and surface microhardness (p = 0.006), with no significant difference in compressive strength compared to control. CONCLUSION: The addition of 3% nisin to HVGIC enhances the antibacterial action against S. mutans and surface microhardness without adversely affecting setting time and compressive strength.

Comparative Evaluation of Surface Defects In Single File Rotary Systems Before and After Instrumentation In Curved Root Canals.

This study aims to evaluate the surface defects and efficiency of two single file rotary systems with different surface treatments in curved root canal instrumentation. A total of 160 root canals were randomly divided into two groups and were subjected to root canal instrumentation with electropolished surface rotary file (Group 1) and with EDM surface treated rotary file (Group 2). All the files were then subjected to SEM analysis to evaluate the surface defects prior to the root canal instrumentation,after 5 uses and 8 uses inside the root canal. From the scanning electron microscopic images, the surface defects as observed were scored and were statistically analyzed. SEM analysis of both the single file systems revealed significantly varying surface defects. Rotary file with electropolishing appeared to be more resistant to deformation compared to the rotary file with EDM treatment after instrumentation of five canals. Hence it can be concluded that electropolished file can be safely instrumented for five times compared to EDM processed files in curved root canals.

Effect of maleic acid and ethylenediaminetetraacetic acid on the shear bond strength of RealSeal SE sealer to root canal dentin.

Aim of this study was to evaluate the effect of 7% maleic acid and 17% ethylenediaminetetraacetic acid (EDTA) on the shear bond strength of RealSeal SE sealer to root canal dentin. Twenty incisors were split into coronal, middle and apical third and were treated in the following manner: Group 1: 5 ml of saline (1 minute). Group 2: 2.5% sodium hypochlorite (5 ml/min) followed by 79% maleic acid (5 ml/min). Group 3: 2.5% sodium hypochlorite (5 ml/min) followed by 17% EDTA (5 ml/min). Sealer was the placed on the root dentin and samples were subjected to bond strength measurement. There was no significant difference in bond strength between maleic acid and 17% EDTA in coronal & middle third. However, in apical third, 7% maleic acid showed higher bond strength. Least bond strength was observed with saline. Bond strength was maximum in apical third for both 7% maleic acid and 17% EDTA.