The effect of fluoride gel on tensile properties, surface morphology and chemical composition of two types of orthodontic wires (an in-vitro study).

OBJECTIVE: Stainless steel and nickel-titanium wires are commonly used in fixed orthodontic appliances. Orthodontists often prescribe fluoride gel to avoid demineralization of teeth. This study investigated the effect of acidulated phosphate fluoride gel on the tensile properties, surface morphology and surface chemical composition of stainless steel and nickel-titanium wires. METHODS: Forty samples of stainless steel and nickel-titanium wires were examined, twenty for each type. Each wire type was divided into four subgroups. The first subgroup was not immersed in fluoride gel and considered as control, while the other three subgroups were immersed in 10 mL of fluoride gel for different periods of time. Then, the wires were removed from the gel, rinsed in a distilled water and left to dry. The ultimate tensile force of each wire was measured using a tensile testing machine. Scanning electron microscope (SEM) and energy-dispersive X-ray spectroscopy (EDX) were used to examine the control and 24 h immersed subgroups. RESULTS: One-way analysis of variance ANOVA showed that there were no significant differences in the ultimate tensile forces between control and fluoride-treated subgroups (P = 0.172 for SS wires and P = 0.672 for NiTi wires). However, changes in the surface morphology and elemental composition of wires were shown by the SEM and EDX. CONCLUSIONS: Although immersion of stainless steel and nickel-titanium wires in the fluoride gel did not affect their tensile properties, however, surface deterioration was evident. So, further investigations are recommended to study the effect of these changes on the oral health of patients.

The effect of incorporation Nano Cinnamon powder on the shear bond of the orthodontic composite (an in vitro study).

OBJECTIVES: One of the causes of dental caries that occurs due to orthodontic treatment is the lack of antibacterial properties in orthodontic adhesive. This study was designated to investigate the effect of orthodontic resin modified by incorporating Nano Cinnamon powder on the shear bond strength of orthodontic brackets. MATERIALS AND METHODS: Heliosit Orthodontic Resin, a photo-activated light cure resin was modified by the addition of Cinnamon in the form of Nano particle powder. Twenty uniform disks were made, 5 as a control and 5 for each concentration of the 1%, 3% and 5% wt/wt Cinnamon modified resin. Their antimicrobial activity against Streptococcus Mutans was tested using the disk diffusion method. Then, the most effective concentration of the modified resin was used to bond metal orthodontic brackets to human extracted premolars. The universal testing machine was used to record the shear bond strength of the control and the modified resin. Also, the adhesive remnant index was measured. RESULTS: Disc diffusion method showed that the 3% wt/wt Cinnamon powder modified resin was more effective than 1% with a larger bacterial inhibition zone. Shear bond strengths of the control were 8.50 MPa and 7.20 MPa for the 3% Cinnamon modified resin with no significant difference between them. Also, no significant difference was recorded in the adhesive remnant index scores between the control and the modified resin groups. CONCLUSION: Findings of this study revealed that the incorporation of 3% Cinnamon Nano particles in orthodontic resin produced an antibacterial effect against Streptococcus mutans without compromising the shear bond strength. CLINICAL RELEVANCE: Incorporation of Cinnamon Nano particles in orthodontic resin may reduce caries formation around brackets during treatment course.

Tensile and transverse strength of novel copolymers for denture base

Objectives: Compare tensile and transverse strength of new copolymers for denture base. Materials and methods: The specimens were prepared from heat cured acrylic resin with three types of additives: Acryester B, Ethoxycarbonylethylene, and Propenoic acid at a percentage of 5% and 10%. The tensile and transverse strains were tested, recorded and compared. Results: The analysis of variance display statistically significant difference. The p-value was 0.001 for each of tensile and transverse strain tests. Conclusions: The tensile strength of the novel copolymers increased. The transverse strength of some of the novel copolymers increased.

The effects of luteolin nanoparticles on the healing of extracted tooth socket in rabbits

Objective: To evaluate the effects of luteolin nanoparticles on the process tooth socket healing in rabbits. Design: This study comprised five rabbits randomly assigned to control animal and experimental animals. Immediately after the extraction of an upper maxillary incisor, the alveolar sockets of experimental animals were treated with topical luteolin while alveolar sockets of the control group remained without treatment. The animals were sacrificed by decapitation with deep anesthesia seven days post tooth extraction. The tooth sockets were sectioned and stained with hematoxylin and eosin stains. Results: Histological evaluation revealed that luteolin treatment induced earlier healing of extracted tooth sockets. Conclusion: These findings suggest that luteolin accelerates the healing process in tooth sockets of rabbits.

FTIR and SEM of a novel chemical conditioning on the zirconia intaglio surface

Objectives: The aim of this study was to evaluate chemical and topographical changes in the intaglio zirconia surface induced by chemical conditioning solutions using FTIR and SEM analysis. Material and method: twelve plates for each FTIR and SEM tests from each zirconia materials (UPCERA HT White, BruxZir® Solid Zirconia, and Copran® Multilayer), milled by a Yenadent CAD/CAM system, sintered and divided randomly into a three groups. A different surface conditioning was applied to the intaglio surface of each group: 30% hydrogen peroxide, 30% citric acid and control group. Result and discussion: by using of the FTIR spectroscopy, an evidence of new bands formation appeared at 1637cm-1 and 3352cm-1 due to the high oxidizing effect of hydrogen peroxide, and at 630cm-1 and 1663cm-1 due to the chelating action of citric acid, and simultaneously, SEM assessment of the surface topography took place, to identify lines, scratches, or surface dissociation that appeared on the intaglio zirconia surface after conditioning. Conclusion: such analysis provides an enhancement of new convenient, less expensive, reliable trials to improve micro-bond strength of luting cement to Y-TZP ceramics.

3-Allyl-1-methyl-1H-benzotriazol-3-ium iodide.

In the crystal structure of 1-methyl-3-allyl benzotriazolium iodide, C(10)H(12)N(3) (+)·I(-), centrosymmetric dimers of coplanar cations are π-stacked with an inter-planar distance of 3.453 (6) Å. The iodide anions are situated above and below the formally positive charged triazolium rings.