Chlorhexidine-Containing Electrospun Polymeric Nanofibers for Dental Applications: An In Vitro Study.

Chlorhexidine is the most commonly used anti-infective drug in dentistry. To treat infected void areas, a drug-loaded material that swells to fill the void and releases the drug slowly is needed. This study investigated the encapsulation and release of chlorhexidine from cellulose acetate nanofibers for use as an antibacterial treatment for dental bacterial infections by oral bacteria Streptococcus mutans and Enterococcus faecalis. This study used a commercial electrospinning machine to finely control the manufacture of thin, flexible, chlorhexidine-loaded cellulose acetate nanofiber mats with very-small-diameter fibers (measured using SEM). Water absorption was measured gravimetrically, drug release was analyzed by absorbance at 254 nm, and antibiotic effects were measured by halo analysis in agar. Slow electrospinning at lower voltage (14 kV), short target distance (14 cm), slow traverse and rotation, and syringe injection speeds with controlled humidity and temperature allowed for the manufacture of strong, thin films with evenly cross-meshed, uniform low-diameter nanofibers (640 nm) that were flexible and absorbed over 600% in water. Chlorhexidine was encapsulated efficiently and released in a controlled manner. All formulations killed both bacteria and may be used to fill infected voids by swelling for intimate contact with surfaces and hold the drug in the swollen matrix for effective bacterial killing in dental settings.

Nanocrystalline cellulose as a reinforcing agent for electrospun polyacrylonitrile (PAN) nanofibers.

OBJECTIVES: Nanocrystalline cellulose (NCC) is a sustainable material with excellent mechanical properties and can potentially be used as a reinforcement agent. The objective of this work was to test the effects of NCC incorporation on the mechanical properties of electrospun polyacrylonitrile (PAN) nanofibers. METHODS: Eleven percent in weight of PAN (molecular weight 150 kD) in a dimethylformamide (DMF) solution was electrospun at 14.6 kV. Nonfunctionalized NCC was added to the solution at 1%, 2%, or 3 wt% (NCC/PAN). Suspensions were mixed and sonicated for 2 h before spinning. Strips (5 × 0.5 cm) were cut from the spun mat, parallel and perpendicular to the rotational direction of the fiber collection drum. Tensile tests were performed, and ultimate tensile strength (UTS), yield strength (YS; 0.3%), elastic modulus (E), and elongation at maximum stress (EMS, %) were calculated from stress-strain plots. Data were analyzed by multiple t tests and one-way ANOVA (α = 0.05). RESULTS: Among all groups, samples with 3 wt % NCC loading had significantly superior mechanical properties. The fiber mats showed anisotropic behavior. CONCLUSIONS: Regardless of concentration, the addition of NCC resulted in increased UTS, E, and YS of the nanofibers.

One-year Clinical Evaluation of Resin Composite Restorations of Noncarious Cervical Lesions in Smokers.

PURPOSE: To evaluate the one-year clinical performance of composite restorations in noncarious cervical lesions placed in smoking and non-smokers using a multimode adhesive system with two adhesive strategies. MATERIALS AND METHODS: Among the selected cervical lesions, four experimental groups were formed based on the patients' smoking habit and bonding strategies with a multimode adhesive system (n = 38): G1: etchand- rinse in non-smokers; G2: selective enamel etching in non-smokers; G3: etch-and-rinse in smokers; G4: selective enamel etching in smokers. The restorations were paired, ie, each patient received at least two restorations. A nanofilled resin composite was applied and light cured incrementally in all groups by one operator. Two calibrated examiners evaluated the restorations at baseline, 6 and 12 months after placement. The modified USPHS criteria were used for evaluation. Data were analyzed using the chi-square (for associations between groups) and McNemar tests. RESULTS: No statistically significant difference was found between groups for the criteria of retention, marginal discoloration, color match, marginal integrity, or sensitivity after 6 and 12 months. The assessments over time showed a statistically significant difference only for marginal discoloration at 12 months for groups 1, 3, and 4 when compared to baseline (p = 0.031). There were no statistical differences for any criteria evaluated among smokers and non-smokers, except for color match, where a difference was found after the baseline evaluation. Regarding the adhesive strategy, etch-and-rinse resulted in a clinical performance similar to that of selective enamel etching over 12 months. CONCLUSION: Neither cigarette smoking habit nor adhesive strategy influenced the clinical performance of resin composite cervical restorations over the first year.

Nanofilled composite restorations with different adhesives strategies: clinical cases.

The esthetic procedures with composites are widely applied, both to posterior and anterior teeth to restore caries cavities, to replace failed restorations, or to make cosmetic procedures. The materials selected to each case may make the difference in the clinical result. This paper presents two clinical cases made with a nanofilled composite resin system used in different bond strategies. In the first, a wide posterior class I restoration, the self-etching strategy was used. The second, an esthetic anterior restoration, was made using the prior etching with phosphoric acid and a hydrophobic adhesive.