Development of Novel Antimicrobial Dental Composite Resin with Nano Cerium Oxide Fillers.

Objectives: To assess the antibacterial efficacy of experimental dental composite resin with cerium oxide nanoparticles as fillers. Methods: The cerium oxide nanoparticles were prepared by the coprecipitation procedure. Synthesized 3wt% CeO2 nanoparticles were added to the composite resin as antibacterial filler. Experimental composite resin was manually prepared by adding ingredients. The resin matrix consisted of two mixed monomers, bisphenol A-glycidyl methacrylate and triethylene glycol dimethacrylate, diketone as the photo initiator, and N, N-dimethylaminoethyl methacrylate as a coinitiator. The antibacterial efficacy against Streptococcus mutans, Streptococcus mitis, Streptococcus aureus, and Lactobacillus spp. bacterial strains was tested using the microdilution method keeping commercially available 3M Filtek Z250 restorative composite as control. Results: The experimental dental composite demonstrated 99.503% efficacy against Streptococcus mutans, 99.441% efficacy against Streptococcus mitis, 99.416% efficacy against Streptococcus aureus, and 99.233% efficacy against Lactobacillus spp. Conclusion: Integrating cerium oxide nanoparticles as fillers into dental composite resin can be promising in terms of antibacterial activity, provided furthermore study has to be conducted to examine other properties. Clinical Significance. Previous studies attempted adding CeO2 nanoparticles into acrylic resins that showed improvement in mechanical properties, but literature is nil on the dental composite resin and cerium oxide nanoparticles. This study demonstrates the development of an experimental antibacterial dental composite resin that can resolve most of the problems related to secondary caries around dental composite restorations.

Comparative evaluation of retreatability of calcium silicate-based root canal sealers and epoxy resin-based root canal sealers in curved canals-An In-Vitro micro-CT analysis.

OBJECTIVE: To compare and evaluate the retreatability of calcium silicate-based root canal sealers and epoxy resin-based root canal sealers in curved canals using micro-CT scanning. MATERIALS AND METHODS: Forty-five maxillary molars with curved roots were selected after confirming with the Schneiders test. Teeth were decoronated near the cemento-enamel junction and moderate to severely curved canals were selected for the study using cone-beam computed tomography. All the samples were subjected to pre-operative micro-CT scanning. Cleaning and shaping were done using step-back preparation, obturation was done using lateral compaction technique, and homogeneous obturation was achieved. All the specimens were kept in 10 mL of phosphate buffered-saline solution at a pH of 8.4 for 48 h and transferred to a plastic container containing moistened foam with 10 mL of phosphate- buffered saline solution, and stored at 37 °C with 100% relative humidity for 4 months. Retreatment was performed for all the samples using Protaper universal retreatment files. Micro-CT scanning was performed to compare and evaluate the remaining sealer volume and resultant cracks formed in the root canal after retreatment. RESULTS: The volume of sealer remaining in the root canal and the length of a crack within the groups were analysed using kruskal-Wallis test and among the groups using post-hoc scheffe test showed that more sealer present in the Diaproseal sealer followed by MTA Fillapex and Bioroot RCS and more crack length was seen in Diaproseal sealer followed by MTA Fillapex and no visible cracks were seen in Bioroot RCS, which had statistically significant results with a P value of < 0.05. CONCLUSION: Within the limitations of the study it was concluded that in-terms of retrievability, Diaproseal sealer was the best among the tested groups followed by MTA Fillapex and Bioroot RCS.

Evaluation of accuracy of fit in cast metal post fabricated with direct and indirect techniques using micro-CT - An in vitro study.

CONTEXT: Accuracy of fit of cast metal posts fabricated with direct and indirect techniques. AIMS: To evaluate the accuracy of fit of cast metal posts fabricated with direct and indirect techniques using micro-CT. MATERIALS AND METHODS: Sixty extracted human maxillary central incisors were used. The teeth were decoronated leaving 2 mm at the cementoenamel junction. Four patterns for each tooth were made including one direct and indirect wax pattern and one direct and indirect resin pattern. In total, 240 patterns and castings were made. Each tooth was scanned using microcomputed tomography (µCT) system with a resolution of 14.5 µm. µCT analyzer Sky scanner software was used to calculate the volume of space between the post and the canals. Statistical analysis used: The student paired t-test and unpaired t-test were used to determine the significant differences between groups. RESULTS: The overall space between the canal walls and posts made with the direct wax and resin technique had an average mean value of 1.10 mm3, whereas with the indirect technique resin and wax pattern, the average mean was 1.30 mm3 which was significant. CONCLUSION: Within the limitations of the study, it was found that the accuracy of fit is better in direct technique using wax pattern.

Effects of chitosan oligosaccharide and calcium hypochlorite on E. Faecali dentinal biofilm and smear layer removal - SEM analysis.

BACKGROUND: The complex structure and irregularities of root canal walls are liable for infection by several bacterial species. Thus, the use of irrigants and auxiliary chemical solutions associated with instrumentation is necessary for effective eradication of the biofilm as well as complete removal of the smear layer. AIM: To evaluate the effects of calcium hypochlorite and chitosan oligosaccharide (COS) in disinfecting Enterococcus faecalis root canal biofilm and smear layer removal with minimal erosion. MATERIALS AND METHODS: A total of 70 mandibular premolars were decoronated at the cementoenamel junction. The samples were biomechanically prepared, sterilized in an autoclave, and incubated with E. faecalis (ATCC-29212) bacteria for 21 days. Cleaning and shaping were done till maximum apical file size of #45 K. Specimens were randomly divided into 4 groups: GROUP I: Control Group, GROUP II: 5% Sodium Hypochlorite (NaOCl) solution followed by 17% EDTA solution, GROUP III: 5% Calcium Hypochlorite [Ca(OCl)2] solution followed by 17% EDTA solution and GROUP IV: 5% Ca(OCl)2 solution followed by 1% COS. The samples were subjected to microbial count followed by smear layer removal under scanning electron microscope (SEM) at coronal, middle and apical third. STATISTICAL ANALYSIS USED: Kruskal-Wallis Test and post-hoc Scheffe's test. RESULTS: It was observed that Group IV showed the lowest amount of CFU count/mL and the highest amount of smear layer removal with a statistically significant difference (P < 0.05) when compared with the other three Groups. CONCLUSION: 5% Ca(OCl)2 solution with 1% COS solution effectively removed the Enterococcus faecalis biofilm and smear layer from the root canals with minimal erosion.

The effect of leachable components of resin cements and its resultant bond strength with lithium disilicate ceramics.

OBJECTIVES: To evaluate the leachable components of resin cements in oral simulating fluids using high performance liquid chromatography and its resultant shear bond strength with ceramics. METHODS: Forty extracted permanent human mandibular molar teeth were sectioned horizontally with a disc beneath the dentino-enamel junction to expose the coronal dentin surface and later finished with 600-grit silicon carbide paper to create a uniform flat surface. Forty Lithium Di-silicate Ceramic block cylinders were sliced in a saw cutting machine at 250 rpm under water-cooling to obtain the discs. The teeth and the ceramic discs were then randomly assigned to two groups on the basis of material used for luting the ceramic disk. Group I: Ceramic disc luted with tooth surface using Variolink II Dual cure Resin Cement, Group II: Ceramic disc luted with tooth surface using multilink speed self-adhesive self-curing resin cement. All ceramic discs were etched with 5% HF acid (IPS Ceramic Etching Gel, Ivoclar, Schaan, Liechtenstein) for 20 seconds, then rinsed thoroughly for 20 seconds and dried for 20 seconds. Ceramic specimens were luted on dentin surfaces with the application of 5 kg load. The samples were stored in 75% ethanol solution for 2 weeks at 37 degree Celsius for chemical aging. HPLC Analysis were performed to analyze the eluted monomer. After HPLC Analysis, Samples were then loaded using universal testing machine for the evaluation of shear bond strength between ceramic discs and the resin cements before and after the elution of monomers. RESULTS: Under HPLC analysis, results showed that the peak release of monomer is Bis-GMA in both the groups. The shear force required to break the bond between the ceramic luted to tooth surface with the resin cements were more for Group I. Statistical results: The statistical analysis was done using ANOVA and paired t-test and it shows P value ≥0.05, hence the null hypothesis is rejected. CONCLUSION: The monomer eluded from all the groups are identified as Bis-GMA, The eluded monomer decreases the bond strength between the resin cement and the ceramic due to water sorption, The Variolink II (dual cure) resin cement shows improved bond strength than the Multilink (self-cure self-adhesive) resin cement.

Effect of vital bleaching with solutions containing different concentrations of hydrogen peroxide and pineapple extract as an additive on human enamel using reflectance spectrophotometer: An in vitro study.

AIM: This study aims to evaluate the color change in human enamel bleached with three different concentrations of hydrogen peroxide, containing pineapple extract as an additive in two different timings, using reflectance spectrophotometer. BACKGROUND: The study aimed to investigate the bleaching efficacy on natural teeth using natural enzymes. MATERIALS AND METHODS: Baseline color values of 10 randomly selected artificially stained incisors were obtained. The specimens were divided into three groups of 20 teeth each: Group 1 - 30% hydrogen peroxide, Group II - 20% hydrogen peroxide, and Group III - 10% hydrogen peroxide. One half of the tooth was bleached with hydrogen peroxide, and other was bleached with hydrogen peroxide and pineapple extract for 20 min (Subgroup A) and 10 min (Subgroup B). STATISTICAL ANALYSIS: The results were statistically analyzed using student's t-test. RESULTS: The mean ΔE values of Group IA (31.62 ± 0.9), Group IIA (29.85 ± 1.2), and Group IIIA (28.65 ± 1.2) showed statistically significant higher values when compared to the mean Δ E values of Group 1A (25.02 ± 1.2), Group IIA (22.86 ± 1.1), and Group IIIA (16.56 ± 1.1). Identical results were obtained in Subgroup B. CONCLUSION: The addition of pineapple extract to hydrogen peroxide resulted in effective bleaching.