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Oral malodor still constitutes a major challenge worldwide. A strong effort is invested in eliminating volatile sulfur compound-producing oral bacteria through organic natural products such as essential oils. Fusobacterium nucleatum is a known volatile sulfur compound-producing bacteria that inspires oral malodor. The aim of the present study was to test the effect of lavender essential oil on the bacterium’s ability to produce volatile sulfide compounds, the principal components of oral malodor. Lavender (Lavandula angustifolia) essential oil was extracted by hydrodistillation and analyzed using GC-MS. The minimal inhibitory concentration (MIC) of lavender essential oil on Fusobacterium nucleatum was determined in a previous trial. Fusobacterium nucleatum was incubated anaerobically in the presence of sub-MIC, MIC, and above MIC concentrations of lavender essential oil, as well as saline and chlorhexidine as negative and positive controls, respectively. Following incubation, volatile sulfur compound levels were measured using GC (Oralchroma), and bacterial cell membrane damage was studied using fluorescence microscopy. Chemical analysis of lavender essential oil yielded five main components, with camphor being the most abundant, accounting for nearly one-third of the total lavender essential oil volume. The MIC (4 µL/mL) of lavender essential oil reduced volatile sulfur compound secretion at a statistically significant level compared to the control (saline). Furthermore, the level of volatile sulfur compound production attributed to 1 MIC of lavender essential oil was in the range of the positive control chlorhexidine with no significant difference. When examining bacterial membrane damage, 2 MIC of lavender essential oil (i.e., 8 µL/mL) demonstrated the same, showing antibacterial membrane damage values comparative to chlorhexidine. Since lavender essential oil was found to be highly effective in hindering volatile sulfur compound production by Fusobacterium nucleatum through the induction of bacterial cell membrane damage, the results suggest that lavender essential oil may be a suitable alternative to conventional chemical-based anti-malodor agents. [ABSTRACT FROM AUTHOR]

The configuration of implant-supported prostheses is considered to influence the magnitude of stress concentrations, affecting their survival rate. The purpose of this study is to determine, through strain gauge measurements during load application, the dispersion and magnitude of strain concentrations in different implant-supported prosthesis designs. All designs matched those commonly used in posterior partially edentulous states. Three implants were inserted into an epoxy resin model (PLM-4B Vishay Measurements Group Inc., Raleigh, NC, USA), allowing for the delivery of three- and four-unit crowns in different cemented configurations. Loads were applied at vertical and oblique directions over the cast crowns in six different configurations representing various posterior partially edentulous restorations. The readings from the strain gauges adhered to the implant necks' presented data on implant strain. Prostheses including cantilevers showed the highest strain among the three-unit prostheses within the prosthetic complex, and three single units showed the least (8133 µs vs. 201 µs, respectively). Angulated load application also had a role in amplifying the strains recorded, resulting in total strains of between 3.5 and 20 times higher than during vertical loading in all configurations. It can be concluded that the configuration of implant-fixed partial prosthesis changes the loads engaging the restoration, the implant, and, probably, the supporting bone. [ABSTRACT FROM AUTHOR]

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Marginal fit is an important clinical factor that affects restoration longevity. The accuracy of three polyvinyl siloxane putty-wash impression techniques was compared by marginal fit assessment using the nondestructive method. A stainless steel master cast containing three abutments with three metal crowns matching the three preparations was used to make 45 impressions: group A = single-step technique (putty and wash impression materials used simultaneously), group B = two-step technique with a 2-mm relief (putty as a preliminary impression to create a 2-mm wash space followed by the wash stage), and group C = two-step technique with a polyethylene spacer (plastic spacer used with the putty impression followed by the wash stage). Accuracy was assessed using a toolmaker microscope to measure and compare the marginal gaps between each crown and finish line on the duplicated stone casts. Each abutment was further measured at the mesial, buccal, and distal aspects. One-way analysis of variance was used for statistical analysis. P values and Scheffé post hoc contrasts were calculated. Significance was determined at .05. One-way analysis of variance showed significant differences among the three impression techniques in all three abutments and at all three locations (P < .001). Group B yielded dies with minimal gaps compared to groups A and C. The two-step impression technique with 2-mm relief was the most accurate regarding the crucial clinical factor of marginal fit. [ABSTRACT FROM AUTHOR]

Objective: To evaluate the influence of different cement combinations on coronal microleakage in restored endodontically treated teeth using dye penetration. Method and Materials: Human, noncarious single-rooted extracted premolars (n = 60) were divided into four experimental groups (each n = 15). After endodontic treatment, different combinations of cements were used to lute prefabricated posts and complete crown restorations: zinc phosphate cement applied on posts and cast crowns (Z) or on zinc phosphate cement posts and resin cement applied on cast crowns (ZR); resin cement applied on posts and zinc phosphate cement applied on cast crowns (RZ); and resin cement applied on posts and cast crowns (R). After artificial aging through thermal cycling (5°C to 55°C) for 2,000 cycles at 38 seconds for each cycle and 15 seconds of dwell time, specimens were immersed for 72 hours in basic fuchsin at 37°C. A buccolingual section was made through the vertical axis of specimens. A Toolmaker's microscope (Mitutoyo) was used to measure (μm) dye penetration. The Kruskal-Wallis nonparametric test was used to determine intergroup difference. A nonparametric Mann-Whitney test compared each group regarding its maximal linear penetration depths on the mesial and distal aspects of each specimen (α = 0.05). Results: Dye staining was evident to some degree in all specimens. Among groups Z, ZR, and RZ, no significant difference was shown in dye-penetration depths (mean penetration scores 1,518 to 1,807 μm). However, dyepenetration depth was significantly lower in group R compared to the other groups (mean penetration score 1,073 μm) (P < .05). Conclusions: Under study conditions, the cement combination offering the best coronal sealing was the one using only resin cement for both posts and crown restorations. [ABSTRACT FROM AUTHOR]