Green synthesis of chitosan- and fluoride-functionalized silver nanoparticles using Camellia sinensis: Characterization and dental applications.

The development of new biocompatible and eco-friendly materials is essential for the future of dental practice, especially for the management of dental caries. In this study, a novel and simple method was applied for the green synthesis of silver nanoparticles (AgNPs) from the aqueous extract of Camellia sinensis (WT) and functionalized with chitosan (CHS) and NaF. The effects of WT_AgNPs application on demineralized dentin were evaluated for potential dental applications. The WT_AgNPs showed molecular groups related to organic compounds, potentially acting as reducing and capping agents. All AgNPs presented spherical shapes with crystal sizes of approximately 20 nm. Forty human molars were assigned to control: sound (SD) and demineralised dentine (DD), and experimental groups: WT_AgNPs, WT_AgNPs_NaF, and WT_AgNPs_CHS. Then, the NPs were applied to DD to evaluate the chemical, crystallographic, and microstructural characteristics of treated-dentine. In addition, a three-point bending test was employed to assess mechanical response. The application of WT_AgNPs indicated a higher mineralisation degree and crystallites sizes of hydroxyapatite than the DD group. SEM images showed that WT_AgNPs presented different degrees of aggregation and distribution patterns. The dentine flexural strength was significantly increased in all WT_AgNPs. The application of WT_AgNPs demonstrated remineralising and strengthening potential on demineralised dentine.

Evaluation of the remineralizing capacity of silver diamine fluoride on demineralized dentin under pH-cycling conditions.

OBJECTIVE: (1) to determine the effects of the silver diamine fluoride (SDF) and sodium fluoride (NaF) in demineralized dentin exposed to an acid challenge by pH-cycling, (2) to evaluate the remineralizing capacity of SDF/NaF products based on the physicochemical and mechanical properties of the treated dentin surfaces. METHODOLOGY: In total, 57 human molars were evaluated in different stages of the experimental period: sound dentin - negative control (Stage 1), demineralized dentin - positive control (Stage 2), and dentin treated with SDF/NaF products + pH-c (Stage 3). Several commercial products were used for the SDF treatment: Saforide, RivaStar, and Cariestop. The mineral composition and crystalline and morphological characteristics of the dentin samples from each experimental stage were evaluated by infrared spectroscopy (ATR-FTIR), X-ray diffraction, and electron microscopy (SEM-EDX) analytical techniques. Moreover, the mechanical response of the samples was analyzed by means of the three-point bending test. Statistics were estimated for ATR-FTIR variables by Wilcoxon test, while the mechanical data analyses were performed using Kruskal-Wallis and Mann Whitney U tests. RESULTS: Regarding the chemical composition, we observed a higher mineral/organic content in the SDF/NaF treated dentin + pH-c groups (Stage 3) than in the positive control groups (Saforide p=0.03; Cariestop p=0.008; RivaStar p=0.013; NaF p=0.04). The XRD results showed that the crystallite size of hydroxyapatite increased in the SDF/NaF treated dentin + pH-c groups (between +63% in RivaStar to +108% in Saforide), regarding the positive control. SEM images showed that after application of the SDF/NaF products a crystalline precipitate formed on the dentin surface and partially filled the dentin tubules. The flexural strength (MPa) values were higher in the dentin treated with SDF/NaF + pH-c (Stage 3) compared to the positive control groups (Saforide p=0.002; Cariestop p=0.04; RivaStar p=0.04; NaF p=0.02). CONCLUSIONS: The application of SDF/NaF affected the physicochemical and mechanical properties of demineralized dentin. According to the results, the use of SFD/NaF had a remineralizing effect on the dentin surface even under acid challenge.

Evaluation of the remineralizing capacity of silver diamine fluoride on demineralized dentin under pH-cycling conditions

Abstract Objective (1) to determine the effects of the silver diamine fluoride (SDF) and sodium fluoride (NaF) in demineralized dentin exposed to an acid challenge by pH-cycling, (2) to evaluate the remineralizing capacity of SDF/NaF products based on the physicochemical and mechanical properties of the treated dentin surfaces. Methodology In total, 57 human molars were evaluated in different stages of the experimental period: sound dentin - negative control (Stage 1), demineralized dentin - positive control (Stage 2), and dentin treated with SDF/NaF products + pH-c (Stage 3). Several commercial products were used for the SDF treatment: Saforide, RivaStar, and Cariestop. The mineral composition and crystalline and morphological characteristics of the dentin samples from each experimental stage were evaluated by infrared spectroscopy (ATR-FTIR), X-ray diffraction, and electron microscopy (SEM-EDX) analytical techniques. Moreover, the mechanical response of the samples was analyzed by means of the three-point bending test. Statistics were estimated for ATR-FTIR variables by Wilcoxon test, while the mechanical data analyses were performed using Kruskal-Wallis and Mann Whitney U tests. Results Regarding the chemical composition, we observed a higher mineral/organic content in the SDF/NaF treated dentin + pH-c groups (Stage 3) than in the positive control groups (Saforide p=0.03; Cariestop p=0.008; RivaStar p=0.013; NaF p=0.04). The XRD results showed that the crystallite size of hydroxyapatite increased in the SDF/NaF treated dentin + pH-c groups (between +63% in RivaStar to +108% in Saforide), regarding the positive control. SEM images showed that after application of the SDF/NaF products a crystalline precipitate formed on the dentin surface and partially filled the dentin tubules. The flexural strength (MPa) values were higher in the dentin treated with SDF/NaF + pH-c (Stage 3) compared to the positive control groups (Saforide p=0.002; Cariestop p=0.04; RivaStar p=0.04; NaF p=0.02). Conclusions The application of SDF/NaF affected the physicochemical and mechanical properties of demineralized dentin. According to the results, the use of SFD/NaF had a remineralizing effect on the dentin surface even under acid challenge.

Gender and Leadership Positions in Spanish Dentistry.

Dentists in Spain reached equal gender representation in 2012 and the number of female dentists has continued to grow (until 57.3% in 2020). This study aims to increase evidence about the gender distribution on the high responsibility positions and opinion leaders of the dental profession and academia. Composition of the executive comities of the main dental institutions of Spain (regional professional associations, national dental association, and scientific societies), members of the Faculty of Dentistry of the University of Granada in 2020 and speakers of the main dental congresses of 2019 (due to the lack of congress in 2020) were recorded and analyzed by genders using chi-squared test (P < .05). Mean representation of female dentists in executive committees of professional associations was 35.6%. More than 70% of presidents and vice-presidents of professional colleges and more than 60% of these positions in scientific societies were occupied by male dentists. None of dental congresses of 2019 reached equal gender participation, being 81.3% of lecturers presenting on main auditoriums male dentists. Although dental workforce in Spain is slightly overrepresented by females, leadership positions and figures among Spanish dentists doesn't seem to reflect the gender distribution of the collective. There is a lack of women occupying high-level positions in dentistry that proves the existence of the so-called "glass ceiling effect" on the profession. Further studies about sociodemographic aspects of dental workforce are needed to develop evidence-based policies for the collective.

Physicochemical and Mechanical Effects of Commercial Silver Diamine Fluoride (SDF) Agents on Demineralized Dentin.

PURPOSE: To investigate the effects of four commercial silver diamine fluoride (SDF) agents on the chemical composition and microstructural properties of dentin, and its relation to the bond strength of two adhesives. MATERIALS AND METHODS: Ninety human molars were randomly divided into sound dentin (negative control), demineralized dentin (positive control), and four experimental groups (n = 15) according to the SDF treatments (Cariestop [Biodinamica Quimica y Farmaceutica], RivaStar 1 [SDI], RivaStar 2 [SDI], and Saforide [Tokyo Seiyaku Kasei]). ATR-FTIR, x-ray diffraction, and SEM techniques were employed to characterize the compositional, crystalline, and microstructural properties of the samples. The microtensile bond strength test evaluated the bonding performance of two adhesives in demineralized dentin treated with SDF agents. RESULTS: Regarding the chemical composition, all SDF-treated groups showed a significantly higher phosphate:organic matrix ratio than the demineralized dentin group (p < 0.05). The XRD analyses revealed that the crystallite size for hydroxyapatite crystals increased on the surface areas (deep, medium, and superficial dentin) for all experimental groups compared to demineralized dentin (p < 0.05). SEM images showed that the behavior of the agents used differs on each surface treated. Bond strength values were adversely affected with both adhesive systems in the four experimental groups (p < 0.05). CONCLUSIONS: The application of SDF agents resulted in the formation of different crystalline phases of silver salts and the increase of mineralization of the pretreated demineralized dentin. However, SDF application showed a negative effect on the bond strength of the adhesives.

Effect of Two Immediate Dentin Sealing Approaches on Bond Strength of Lava™ CAD/CAM Indirect Restoration.

The objective of this work was to compare the micro-tensile bond strength (µTBS) of CAD/CAM (Computer-Aided Design/ Computer-Aided Manufacturing) specimens cemented with different pairing of adhesives and resin-cements using two Immediate Dentin Dealing (IDS) approaches in comparison with Delay Dentin Sealing (DDS). Coronal dentin from 108 molars were divided into nine groups (n = 12) depending on the adhesive/resin-cement (A-C) assigned. Lava™ Ultimate (4 × 10 × 10 mm) was cemented according to different strategies: IDS1(cementation after dentin sealing), DDS (dentin sealing and cementation at 2-weeks), IDS2 (immediate dentin sealing and cementation at 2-weeks). Samples were sectioned and tested until failure to determine the µTBS. Failure mode was categorized as dentin/cement (DC), at Lava™ Ultimate/cement (LC) and hybrid (H). Kruskal-Wallis and Mann-Whitney U tests and influence of the type of failure on the µTBS by survival analysis with competing risk was explored. Mostly, µTBS values were equal or higher in IDS2 than DDS. In general, A-Cs that showed higher µTBS, have high percentages of LC failure. Survival analysis with competing risk between DC + H and LC values showed that some A-Cs would significantly increase the µTBS values for IDS2. A-Cs with the highest adhesion values showed a high percentage of fractures at the LC interface, suggesting that the adhesion at the adhesive/dentin interface would be higher.

Influence of de-remineralization process on chemical, microstructural, and mechanical properties of human and bovine dentin.

OBJECTIVES: This study compared the chemical composition, microstructural, and mechanical properties of human and bovine dentin subjected to a demineralization/remineralization process. MATERIALS AND METHODS: Human and bovine incisors were sectioned to obtain 120 coronal dentin beams (6 × 1 × 1 mm3) that were randomly allocated into 4 subgroups (n = 15) according to the time of treatment (sound, pH-cycling for 3, 7, and 14 days). Three-point bending mechanical test, attenuated total reflectance-Fourier transform infrared (ATR-FTIR), thermogravimetric (TG), and X-ray diffraction (XRD) techniques were employed to characterize the dentin samples. RESULTS: Regarding chemical composition at the molecular level, bovine sound dentin showed significantly lower values in organic and inorganic content (collagen cross-linking, CO3/amide I, and CO3/PO4; p = 0.002, p = 0.026, and p = 0.002, respectively) compared to humans. Employing XRD analyses, a higher mineral crystallinity in human dentin than in bovines at 7 and 14 days (p = 0.003 and p = 0.009, respectively) was observed. At the end of the pH-cycling, CI (ATR-FTIR) and CO3/PO4 ratios (ATR-FTIR) increased, while CO3/amide I (ATR-FTIR), PO4/amide I (ATR-FTIR), and %mineral (TG) ratios decreased. The extension by compression values increased over exposure time with significant differences between dentin types (p < 0.001, in all cases), reaching higher values in bovine dentin. However, flexural strength (MPa) did not show differences between groups. We also observed the correlation between compositional variables (i.e., PO4/amide I, CI, and %mineral) and the extension by compression. CONCLUSIONS: Human and bovine dentin are different in terms of microstructure, chemical composition, mechanical strength, and in their response to the demineralization/remineralization process by pH-cycling. CLINICAL RELEVANCE: These dissimilarities may constitute a potential limitation when replacing human teeth with bovines in in vitro studies.

Dental Management of a Child with Incidentally Detected Hemophilia: Report of a Clinical Case.

Children with hemophilia (A or B) are at risk for bleeding episodes, which rank from mild mucosal/soft tissues bleeding to life-threatening hemorrhages. This report describes the dental/medical management provided to an 8.10-year-old patient suffering from uncontrolled bleeding after a surgical procedure to expose both permanent upper central incisors, in which hemophilia was a pure incidental finding. Additionally, diverse precautions to be considered during the dental clinical treatment of hemophilic children are discussed.

Demineralization effects of hydrogen peroxide on bovine enamel and relation to shear bond strength of brackets.

PURPOSE: To measure the demineralization capacity of 37% phosphoric acid and shear bond strength (SBS) of brackets attached on bovine enamel at different times after bleaching with 30% hydrogen peroxide. MATERIALS AND METHODS: Four equally-sized pieces of each crown from 18 bovine incisors were randomly distributed among 7 groups (n = 10). After bleaching with 30% hydrogen peroxide for 1 h, specimens were stored in artificial saliva for 0 h, 24 h, or 1, 2, 3, or 4 weeks before bonding specimens to brackets. An unbleached group of specimens served as controls. Shear bond strength (SBS in MPa) was measured with a universal testing machine. Adhesive Remnant Index (ARI) scores were determined after failure of bracket bonds. To measure demineralized Ca2+, four 4 x 4 mm sections from each of 15 bovine incisors were randomly distributed among 4 groups (n = 15). Specimens were stored in artificial saliva for 0 h, 24 h or 7 days after bleaching and then immersed in 37% phosphoric acid solution. After 15 s, 30 s, and 60 s, 5-ml aliquots of solution were removed for spectrophotometry. Unbleached specimens served as controls. RESULTS: Larger amounts of Ca2+ were extracted from the enamel by phosphoric acid up to 24 h after application of hydrogen peroxide, when there was also a significant decrease in bracket-enamel SBS. After 1 week, there were no changes in amounts of Ca2+ extracted, and SBS values returned towards unbleached values. CONCLUSION: Lower bracket-enamel SBS values at 24 h after bleaching are closely correlated with the larger amounts of Ca2+ extracted from the enamel.

A new approach to endodontic treatment and operative procedure in nonendodontically treated posterior crown root fractures.

We report a case of nonendodontically treated first upper premolar crown root fracture in which the palatal cusp fracture extended below the cementoenamel junction. Reattachment of the palatal cusp in its original position by acid-etch and flowable composite allowed the creation of a standard access opening as in an intact tooth, avoiding apex location errors and contamination of the root canal. During crown-lengthening surgery, the palatal cusp fragment was hollowed out and used as a natural individual matrix for placement of the core material.

Effects of filling techniques on the regional bond strength to lateral walls in Class I cavities.

OBJECTIVES: Using the push-out technique, this study compared the influence of different composite insertion techniques in Class I cavities on the regional shear bond strength to lateral walls. MATERIALS AND METHOD: Standardized Class I cavities were prepared on the occlusal surface of 60 freshly extracted third molars, which were randomly assigned to one of five groups (n = 10). The cavities were bonded with the self-etch adhesive AdheSE and restored with Tetric Ceram resin composite by one of five techniques: G1, incremental technique (four oblique layers); G2, flowable composite as liner and bulk technique; G3, bulk technique and G4, light cone technique. The total-etch adhesive (Single Bond) and incremental technique were used as the control procedure. Each specimen was sectioned perpendicular to the long axis of the tooth in 1 mm-thick dentin slices. A push-out test was performed to measure regional bond strengths and identify the type of failure. Two additional teeth per group were prepared for the morphological interface study using scanning electron microscopy. RESULTS: Differences between the groups were tested by one-way ANOVA and Scheffé post hoc test (F = 29.635, p < 0.001). The highest shear bond strength values were obtained with the incremental technique, regardless of the adhesive used. Significant differences in bond strength to superficial and deep dentin were only found when a total-etch adhesive was used (Single Bond). CONCLUSIONS: Use of the incremental technique with total-etch or self-etch adhesives is the most effective method of inserting resin-based composites in large Class I cavities.

Increased fluoride uptake in human dental specimens treated with diode laser.

The hypothesis of this study was the fact that diode lasers can increase the fluoride uptake in dental structures. The main objectives were: (1) to evaluate the effect of diode laser-NaF varnish combination on binding fluoride to dental enamel in an in vitro model and (2) to analyse outer enamel surface changes produced by the laser energy. After NaF enamel varnish and laser irradiation at different levels of energy, specimen surfaces were examined by environmental scanning electron microscopy. The incorporation of F(-) ion into the dental structure was quantitatively determined by using a fluoride ion-selective electrode. Results showed that the laser treatment significantly increased the binding of fluoride to the enamel surface without damaging it. The amount of F(-) estimated was 37 +/- 7 mg/l to the power of 5 W and 58 +/- 12 mg/l to the power of 7 W. These increases were significantly greater than the ones achieved by conventional topical fluoridation. The results were analysed and compared by Kruskal-Wallis and Dunn's multiple comparison tests, and significant statistical differences were found. These suggest that the NaF varnish-diode laser combination may be a useful option for the effective fluoridation of teeth.

Influence of ceramic surface conditioning and resin cements on microtensile bond strength to a glass ceramic.

STATEMENT OF PROBLEM: It is not clear how different glass ceramic surface pretreatments influence the bonding capacity of various luting agents to these surfaces. PURPOSE: The purpose of this study was to evaluate the microtensile bond strength (microTBS) of 3 resin cements to a lithia disilicate-based ceramic submitted to 2 surface conditioning treatments. MATERIAL AND METHODS: Eighteen 5 x 6 x 8-mm ceramic (IPS Empress 2) blocks were fabricated according to manufacturer's instructions and duplicated in composite resin (Tetric Ceram). Ceramic blocks were polished and divided into 2 groups (n=9/treatment): no conditioning (no-conditioning/control), or 5% hydrofluoric acid etching for 20 seconds and silanization for 1 minute (HF + SIL). Ceramic blocks were cemented to the composite resin blocks with 1 self-adhesive universal resin cement (RelyX Unicem) or 1 of 2 resin-based luting agents (Multilink or Panavia F), according to the manufacturer's instructions. The composite resin-ceramic blocks were stored in humidity at 37 degrees C for 7 days and serially sectioned to produce 25 beam specimens per group with a 1.0-mm(2) cross-sectional area. Specimens were thermal cycled (5000 cycles, 5 degrees C-55 degrees C) and tested in tension at 1 mm/min. Microtensile bond strength data (MPa) were analyzed by 2-way analysis of variance and Tukey multiple comparisons tests (alpha=.05). Fractured specimens were examined with a stereomicroscope (x40) and classified as adhesive, mixed, or cohesive. RESULTS: The surface conditioning factor was significant (HF+SIL > no-conditioning) (P<.0001). Considering the unconditioned groups, the microTBS of RelyX Unicem was significantly higher (9.6 +/- 1.9) than that of Multilink (6.2 +/- 1.2) and Panavia F (7.4 +/- 1.9). Previous etching and silanization yielded statistically higher microTBS values for RelyX Unicem (18.8 +/- 3.5) and Multilink (17.4 +/- 3.0) when compared to Panavia F (15.7 +/- 3.8). Spontaneous debonding after thermal cycling was detected when luting agents were applied to untreated ceramic surfaces. CONCLUSION: Etching and silanization treatments appear to be crucial for resin bonding to a lithia disilicate-based ceramic, regardless of the resin cement used.

Molarization and development of multiple supernumerary teeth in the premolar region.

This case is the radiological diagnosis of a supernumerary premolar with the molarization of both lower second premolars in a 12-year-old child. Ten years after the diagnosis, the delayed development of another 4 supernumerary premolars was detected. Orthopantomography during mixed dentition allowed the detection of anomalies not clinically suspected. Any alteration in the number of teeth should suggest the potential of associated dental anomalies, indicating the long-term clinical and radiological follow-up of the patient during the second decade of life.