Prevalence and antimicrobial resistance of bacterial agents isolated from the cases of dental caries.

Dental caries are mainly occur owing to the presence and activity of bacterial agents. The present study was done to assess the prevalence and antibiotic resistance of bacterial strains isolated from the cases of dental caries. Fifty patients with approved dental carries were included in the study. Sampling from the site of dental caries was done using the sterile swab. Swabs were transferred to laboratory and subjected to microbial culture. Species identification of bacteria was done using biochemical test. Bacterial isolates were subjected to disk diffusion to assess their antimicrobial resistance. S. aureus (40%) harboured the highest rate of contamination, while S. oralis (16%) and E. aerogenes (10%) harbored the lowest. S. aureus and S. mutans (6%) harbored the highest distribution amongst the cases of mix infections, while S. aureus and S. oralis (2%) harbnored the lowest. S. aureus strains harbored the highest rate of resistance toward tetracycline (90%), penicillin (75%), ampicillin (75%), amoxicillin (60%), and erythromycin (60%). E. coli strains harbored the highest rate of resistance toward tetracycline (90%), gentamicin (80%), ampicillin (70%), and erythromycin (70%). S. mutans strains harbored the highest rate of resistance toward tetracycline (93.33%), ampicillin (86.66%), penicillin (80%), amoxicillin (80%), and erythromycin (80%). S. oralis strains harbored the highest rate of resistance toward tetracycline (100%), ampicillin (75%), penicillin (62.50%), and amoxicillin (62.50%). E. aerogenes strains harbored the highest rate of resistance toward tetracycline (80%), gentamicin (80%), and ampicillin (80%). S. aureus bacteria isolated from dental caries harbored the highest rate of MDR. Distribution of resistance against more than 3 antimicrobial agents amongst the S. aureus, E. coli, S. mutans, S. oralis, and E. aerogenes bacteria isolated from the cases of dental caries was 90%, 60%, 80%, 62.50%, and 80%, respectively. Application of disk diffuin can help practitioners to reduce the rate of resistance in bacteria responsible for dental caries.

Shear Bond Strength of Colored and Sandblasted Zirconia to Ceramic Veneers Fabricated by the Pressing and Layering Techniques: An In Vitro Study.

Introduction: Porcelain-veneered zirconia (PVZ) restorations are increasingly used due to their optimal esthetics and high strength. However, chipping of porcelain limits the application of PVZ restorations. The aim of this study was to assess the shear bond strength (SBS) of colored and sandblasted zirconia to ceramic veneers fabricated by the pressing and layering techniques. Materials and Methods: Sixty cubic zirconia specimens (10 × 10 × 2 mm) were assigned to three groups according to their surface treatment: (I) control, (II) sandblasting with 50 µm alumina particles (S), and (III) coloring (C). Each group was subsequently divided into two subgroups according to the porcelain-veneering technique: (I) layering (L) and (II) pressing (P). The specimens underwent 10,000 thermal cycles between 5 and 55°C, and their biaxial SBS was measured in an electromechanical universal test machine (0.5 mm/min with 2.5 kN load cell). The failure mode was also assessed under a stereomicroscope. Three samples were randomly selected from each subgroup (n = 18) for examination of zirconia-phase transformation by X-ray diffraction (XRD). Two-way and one-way ANOVA followed by the post hoc Tukey test were used to analyze statistical differences among the groups and subgroups (α = 0.05). Results: The sandblasted zirconia with press porcelain (SP) subgroup showed the highest (24.40 ± 8.16 MPa) and the colored zirconia with press porcelain (CP) subgroup showed the lowest (13.76 ±3.62 MPa) SBS. All failures were cohesive. Rate of phase transformation in layered porcelain was significantly lower than that in pressed porcelain (P < 0.01). Conclusion: The sandblasted group showed the highest and the colored group showed the lowest SBS; the layered group showed higher SBS than the pressed group.