Comparison of four cordless gingival displacement systems: A clinical study.

STATEMENT OF PROBLEM: Although the conventional chemicomechanical cord technique is widely used, packing the cord into the sulcus may cause pain and bleeding. Cordless displacement techniques have been introduced, but a comparison of these systems is lacking. PURPOSE: The purpose of this clinical study was to evaluate the efficiency and gingival response of 4 cordless gingival displacement systems. MATERIAL AND METHODS: One hundred twenty teeth in 30 participants were allocated to 4 groups according to the material used: Tr (Traxodent; Premier Dental Products Co), Es (Expasyl; Acteon UK), Ez (Expazen; Acteon UK), and Mr (3M Retraction; 3M ESPE). Baseline measurements of periodontal indices and a digital scan were acquired. The cordless displacement pastes were applied according to the manufacturer's instructions. After removal, a second scan was acquired. Participants were recalled on the 2nd and 14th day to measure periodontal indices and for scans. Screenshots were superimposed to measure changes in the gingiva. Statistical differences among the different materials in achieving lingual and buccal vertical gingival displacement were tested using the related-samples Friedman 2-way ANOVA test by ranks at 3 time points such as immediate, at 2 days, and at 14 days (α=.05). RESULTS: Immediate gingival displacement varied with the system used. For horizontal displacement, median values ranged between 150 µm (Tr) and 725 µm (Ez) for buccal displacement and between 93 µm (Tr) and 550 µm (Ez) for lingual displacement. Minimum and maximum displacements also varied and followed a similar trend, with Traxodent providing the lowest displacement. The plaque index and attachment level did not statistically differ before and after the treatment. The periodontal parameters were not statistically significant among the groups at all time intervals, except for the gingival index that increased for all the groups after 2 days. CONCLUSIONS: Significant differences were found among the 4 tested systems in both vertical and horizontal gingival displacement. Expasyl, Expazen, and 3M Retraction exceeded the 200-µm requirements for horizontal displacement. Traxodent provided the least displacement in both vertical and horizontal dimensions.

Chemical analysis of aqueous extracts of Origanum majorana and Foeniculum vulgare and their efficacy on Blastocystis spp. cysts.

BACKGROUND: Origanum majorana (O. majorana) and Foeniculum vulgare (F. vulgare) are traditionally used herbs in Egypt for treatment of several diseases including parasitic diseases. The Purpose was to determine the efficacy of O. majorana and F. vulgare aqueous extracts (AEs) on Blastocystis spp. in vitro, and to reveal their phenolic, flavonoids components and antioxidant activities through chemical analysis. METHODS: The Efficacy of both plant AEs on human Peripheral Blood Mononuclear Cells (PBMCs) viability was assessed using MTT assay. Isolated Blastocystis spp. cysts from patients' diarrhea samples were incubated with different concentrations of O. majorana and F. vulgare AEs for different incubation periods (24, 48 and 72 h) in comparison with nitazoxanide (NTZ) as a drug control. The total contents of phenolic and flavonoid compounds in the AEs and their ability to reduce DPPH were assessed. High performance liquid chromatography (HPLC) analysis for quantitative and qualitative determination of the phenolic and flavonoid contents was performed. RESULTS: O. majorana AE at a dose of 400 µg /ml showed efficacy rates of 96% and 100% against Blastocystis parasite after 48 and 72 h, respectively, which nearly equivalent to NTZ at a dose of 500 µg/ml. F. vulgare at a dose of 250 µg/ml showed less efficacy rate of 56.4% after 48 h and increased to 70.7% after 72 h. Both extracts contain high phenolic and flavonoid compounds that possess antioxidant and free radical scavenging activities. CONCLUSION: O. majorana and F. vulgare AEs showed dose and time dependent anti-Blastocystis activity.

Effect of screw-access channels on the fracture resistance of 3 types of ceramic implant-supported crowns.

STATEMENT OF PROBLEM: Access channels for retrieving ceramic implant-supported screw-retained crowns may decrease their fracture resistance. PURPOSE: The purpose of this in vitro study was to evaluate the effect of screw-access channels on 3 types of ceramic implant-supported crowns. MATERIAL AND METHODS: Sixty computer-aided designed and computer-aided manufactured (CAD-CAM) ceramic implant-supported screw-retained maxillary premolar crowns were fabricated, 30 with an occlusal screw-access channel and 30 without access channels. Each group was further divided into the following 3 subgroups of 10 specimens each: monolithic zirconia, veneered zirconia, and lithium disilicate. Identical milled titanium implant abutments were fabricated. Crowns were fabricated with standardized thicknesses and subjected to cyclic loading until failure occurred. Data analysis was performed using 1-way analysis of variance test of significance followed by Tukey honest significant difference (HSD) test (α=.05). RESULTS: No significant differences in fracture resistance were found between access channel groups and corresponding groups without access channels (P>.05). Among the subgroups, monolithic zirconia recorded the highest fatigue failure mean load values (2047.8 ±83.2 N for crowns with access channels and 2028.7 ±104.5 N for crowns without access channels), which was significantly higher (P<.05) than values for the lithium disilicate group (605.4 ±37.9 N for crowns with access channels and 615.3 ±76.6 N for crowns without access channels) and the veneered zirconia group (411 ±34.4 N for crowns with access channels and 461.2 ±72.7 N for crowns without access channels), which recorded the lowest fatigue failure load mean values. CONCLUSIONS: Screw-access channels did not affect the fatigue failure load of monolithic zirconia, monolithic lithium disilicate, or veneered zirconia ceramic crowns. Monolithic zirconia crowns recorded significantly higher fatigue failure load among the 3 types of crowns tested.

Comparison of interim restorations fabricated by CAD/CAM with those fabricated manually.

STATEMENT OF PROBLEM: Interim restorations represent an essential treatment step; however, the optimal resin material for long-term interim restorations requires investigation. PURPOSE: The purpose of this in vitro study was to compare the color stability, water sorption, wear resistance, surface hardness, fracture resistance, and microleakage of computer-aided design/computer-aided manufacturing-(CAD/CAM) fabricated interim restorations with those of manually fabricated interim restorations. MATERIAL AND METHODS: Epoxy replicas were made from a prepared maxillary first premolar. On the replicas, interim crowns were fabricated and divided into the following groups: CAD/CAM poly(methyl methacrylate) (PMMA) blocks (CC), autopolymerizing temporary resin (AP), automix temporary resin (AM), and thermoplastic resin (TP). After cementation, all specimens were subjected to thermocycling and dynamic fatigue. The CIE Laboratory color coordinates were then recorded before and after immersion in coffee, tea, carbonated cola, and red wine. Water sorption was evaluated by using an immersion technique. Wear resistance was measured in a surface abrasion device. Vickers microhardness was measured on polished specimens. Fracture resistance was evaluated by axial loading with a universal testing machine. Marginal dye penetration was evaluated by sectioning the interim restorations after immersion in methylene blue (α=.05). RESULTS: Colorimetric analysis revealed a large degree of color alteration (ΔE) in the manually fabricated interim restorations: AP = ΔE of 6.7 ±2); AM = ΔE of 7.1 ±1.5), and TP = ΔE of =5.4 ±3.1. The CC group demonstrated color stability (ΔE=2.1 ±0.2). CAD/CAM interim restorations demonstrated significantly lower water sorption, higher wear resistance, higher surface hardness, and significantly higher fracture resistance (1289±56N) compared with manually fabricated interim restorations (AP=996 ±45, AM=899 ±37, and TP=1179 ±41). The stereomicroscopic examination of sectioned specimens demonstrated the absence of dye penetration in all tested specimens. CONCLUSIONS: CAD/CAM interim crowns presented stable physical and mechanical properties and may be used for long-term interim restorations.