فهرست مطالب farzaneh sadeghi mahounak

 Dental caries is an infectious disease caused by bacterial colonization and biofilm formation. Streptococcus mutans (S. mutans) is mainly responsible for dental caries development. Considering the side effects of synthetic antibacterial agents, attempts are ongoing to find antimicrobial agents with minimal or no side effects for preventing dental caries. Based on the reported antibacterial activity of chitosan, this in vitro study aimed to assess the antibacterial and anti-biofilm effects of chitosan nanoparticles on S. mutans clinical isolates. 

 S. mutans isolates were isolated from supragingival plaque and carious lesions of patients by standard biochemical tests and Polymerase Chain Reaction (PCR) of the gtfB gene. The antibacterial activity and Minimum Inhibitory Concentration (MIC), Minimum Bactericidal Concentration (MBC) of chitosan nanoparticles against S. mutans was evaluated by the agar well-plate and broth micro-dilution test, respectively. Also, the effect of chitosan nanoparticles on biofilm formation was evaluated using micro-titer plate method. Data were analyzed using ANOVA.

 Fifteen S. mutans isolates were collected from patients. The chitosan nanoparticles synthesized had a diameter of 20–30 nm. The chitosan nanoparticles showed antibacterial activity against S. mutans isolates. MICs and MBCs ranged from 0.625-2.5 µg/ml and 1.25-5 µg/ml, respectively. All isolates evaluated in this study were biofilm-forming and 5 of these produced a strong biofilm. The chitosan nanoparticles inhibited biofilm formation at 0.75 µg/ml concentration. 

 Chitosan nanoparticles had antibacterial and anti-biofilm activity on S. mutans clinical isolates. This study suggests the potential of chitosan nanoparticles as antimicrobial agents against cariogenic Streptococci.

Restoration of severely damaged endodontically treated anterior teeth typically poses a challenge. Specific indication of post-retained restorations in such teeth has reasonably been questioned because of the potential tooth structure weakening. The present study aimed to describe a modified conservative endocrown (modified refers to intracanal extension while conservative refers to preparation at the finish line) to rehabilitate severely damaged anterior teeth.

Endodontically treated lower right central incisor had inadequate remaining tooth structure and restored by endocrwn restoration as a definitive treatment and followed for 30 month.

Considering the clinical outcome after 30 months of follow-up, it seems that this specific type of endocrown could efficiently serve as a conservative treatment approach to restore endodontically treated anterior teeth.

Toothpastes and mouthwashes contain ingredients that may be toxic for oral mucosal tissues. This study aimed to assess the cytotoxicity of the ingredients of commonly used toothpastes and mouthwashes.

This experimental study was performed on 16 toothpastes and four mouthwashes widely available in the Iranian market. First, the concentration of six main ingredients of these products, namely sodium fluoride (NaF), sodium lauryl sulfate, cocamidopropyl betaine, zinc lactate, paraben, and sodium benzoate, was determined. The methyl thiazolyl tetrazolium (MTT) assay was used to assess the cytotoxicity of these materials for human gingival fibroblasts (HGFs). The MTT assay was performed at 1, 15, and 30 minutes following exposure to five concentrations of each material in triplicate (according to the concentrations obtained in the isolation step). Data were analyzed using three-way analysis of variance (ANOVA).

The difference in the cytotoxicity of the materials was statistically significant (P<0.001). Cytotoxicity was time- and concentration-dependent; by an increase in the concentration of the materials, their cytotoxicity increased over time. The cytotoxicity of sodium lauryl sulfate and cocamidopropyl betaine was >90%. The cytotoxicity of NaF varied from 25% to 70%, and the cytotoxicity of all concentrations of zinc lactate and sodium benzoate was <50% for HGFs.

To decrease the cytotoxic effects of toothpastes, sodium lauryl sulfate and cocamidopropyl betaine should be replaced with safer detergents, and the concentration of fluoride should be decreased to 400 parts per million (ppm). Alternatively, fluoride may be replaced with other antibacterial and cariostatic agents.

Color change of cements over time can be detected through translucent ceramic veneers, compromising the aesthetic appearance of restorations in the long-term. This study aimed to assess the color stability of ceramic laminate veneers cemented with self-adhesive resin cements after accelerated aging.

In this study, 21 IPS e.max ceramic discs, measuring 8mm in diameter and 0.7 mm in thickness, were fabricated and divided into three groups (n=7) for the application of Choice 2 total-etch light-cure resin cement, RelyX U200 dual-cure self-adhesive resin cement, and SpeedCEM self-cure self-adhesive resin cement. The ceramic discs in each group were cemented on the prepared facial surface of bovine teeth. The color parameters were assessed using a spectrophotometer. Subsequently, the samples were subjected to accelerated aging for 100 hours, and the color parameters were measured again. The data were analyzed using two-way repeated-measures analysis of variance (ANOVA) and Tamhane’s post-hoc test (P<0.05).

Aging significantly affected the ceramic laminate color parameters in all three groups (P<0.05). SpeedCEM cement showed the lowest color stability (∆E=4.2) after aging, and its color change was clinically unacceptable (∆E>3.5). The color change of the other two groups was clinically acceptable (1<∆E<3.5).

The self-adhesive dual-cure cement showed color stability comparable to that of the total-etch light-cure cement for cementation of IPS e.max ceramic laminates. The color stability of both cements was superior to that of the self-adhesive self-cure cement.