Comparison of Antimicrobial Effects of Stevia Rebaudiana Extract and Xylitol on Dental Biofilm: An In Vitro Study

Objectives This study aimed to assess the antibacterial effects of xylitol and Stevia rebaudiana (S. rebaudiana) ethanolic extract on oral biofilm. Methods A total of 96 acrylic discs were divided into two main groups for inoculation with Streptococcus mutans (S. mutans) and Streptococcus sobrinus (S. sobrinus). Each group consisted of 6 subgroups including a positive control subgroup and 5 subgroups of discs immersed in 1% or 3% xylitol solutions, 2 or 4 mg/mL S. rebaudiana, or a combination of 3% xylitol and 4 mg/mL S. rebaudiana. After incubation, the discs were rinsed and transferred to fluid universal medium. The solutions were cultured on specific culture media and incubated. The colony-forming units (CFUs) were counted for each disc. The structure of biofilm in each group was evaluated under a scanning electron microscope (SEM). Results ANOVA revealed significant differences between the subgroups in both S. mutans and S. sobrinus groups (P=0.03 and P=0.01, respectively). In S. mutans group, the logarithmic mean of colony count in the positive control subgroup was 6.75 while this value was significantly lower in 2 mg/mL (5.81) and 4mg/mL (5.92) S. rebaudiana subgroups using the post hoc Dunnett's test (P=0.01 and P=0.04, respectively). The three other subgroups did not show significant differences. In S. sobrinus group, all five experimental subgroups demonstrated significantly lower colony count than the positive control group (P<0.05).  Conclusion S. rebaudiana extract appears to be more potent than xylitol against dental biofilm

Comparison of the human bone matrix gelatin (HBMG) with autogenous bone graft in reconstruction of the parietal bone defects in rat: a histological and radiographic study

Background and aims. Autogenous bone graft is commonly used for reconstruction of bone defects in routine surgical procedures. The complexity of producing bone grafts and their application has lead to the use of human bone matrix gelatin (HBMG). The present study was conducted to compare the efficacy of HBMG and autograft on the reconstruction of bone defects in rats.
 Materials and methods. In this cross-sectional, experimental study, two defects were put on left and right sides of parietal bone of rats. HBMG was placed randomly on defects of one side and autograft in the defects of the other side. All specimens were assessed and compared with each other according to histological and radiographic characteristics. Other assessments included amount and the rate of bone formation, inflammation signs, fibrosis tissue and cartilage formation and also radiographic characteristics of grafts, assessed by digital and film-based methods. Mann-Whitney U test was used for statistical analysis.
 Results. The results showed a reduction of inflammation and an increase in new bone formation in both groups in 7, 14, 28 and 60 days after surgery. Bone formation with HBMG on day 24 was more than autograft. However, there was no significant difference between the groups on day 60. Superiority of digital method to film-based method of imaging was also observed.
 Conclusion. Although HBMG has the same efficacy as autograft, the rate of bone reconstruction with HBMG is higher. HBMG also induces focal, rather than peripheral, bone construction in the defect