Bibliometric analysis and evaluation of the Journal of Prosthetic Dentistry from 1970 to 2019.

STATEMENT OF PROBLEM: A comprehensive bibliometric analysis to determine different aspects of the Journal of Prosthetic Dentistry is lacking. PURPOSE: The purpose of this bibliometric study was to analyze the characteristics of the Journal of Prosthetic Dentistry between 1970 and 2019. MATERIAL AND METHODS: The Web of Science Core Collection was used to retrieve 9 categories of the Journal of Prosthetic Dentistry, including keywords and terms used, cited documents published, the countries and organizations of the authors, references, and sources cited during this period. Data were exported to a software program and analyzed for each 10-year period and for the entire 50 years. The highest 10 in each category were reported. Co-occurrence, couthorships, and linkage were also reported. RESULTS: A total of 11 989 records were reached by the search on the Web of Science Core Collection database; of which, 10 638 (92.9%) were included in the analysis. Articles made up 91.1%, of all records, with 217 review documents (1.8%). The most productive decade was 1980 to 1989 with 2936 documents. The total number of citations of all documents (available period 1980 to 2019) including self-citations was 155 112. During the period 1970 to 2019, 14 837 terms were used. The total number of keywords was 4933 (available period 1990 to 2019). There were 15 382 authors, 82 countries, and 2113 organizations identified in articles published in the Journal of Prosthetic Dentistry during this period, with most from the United States. There were 43 027 authors, 95 324 references, and 14 594 sources cited in the Journal of Prosthetic Dentistry during the period surveyed. CONCLUSIONS: This bibliometric analysis provided a comprehensive overview of the impactful role of the Journal of Prosthetic Dentistry in contemporary dentistry, particularly in the field of prosthodontics.

Pit and Fissure Sealant versus Fluoride Varnish for the Prevention of Dental Caries in School Children: A Systematic Review and Meta-Analysis.

Children's dental health has become the main concern, due to the increase in caries prevalence amongst children. Pit and fissure sealant (PFS) and fluoride varnish (FV) are effective measures for preventing dental caries. However, the clinical efficacy of these interventions when compared to one another is uncertain. The aim of the present systematic review with meta-analysis was to compare pit and fissure sealants with fluoride varnish for caries prevention of first permanent molars among schoolchildren. This is a meta-Analysis, which involves randomized control trials that compare the effectiveness of PFS with FV within 24 months of follow-up. Five databases were searched from 1990 to 2019 to identify studies published in Arabic or English language. The risk ratio (RR) and 95% confidence intervals (CIs) were calculated using a random-effects model. A total number of 4 studies were included with overall of 1249 children in both groups. Three included trial reported caries increment of first permanent molars (FPM) with 24 months of follow-up, there was no statistical significance (RR: 0.65; 95% CI 0.31 to 1.35; P = 0.26 I2 = 89%). As regards DMFS increment, the analysis showed no statistical differences between FV and PFS in terms of lowering DMFS increment (MD: 0.09; 95% CI: -0.03 to 0.21). Findings of this meta-analysis proved there is no significant difference between PFS and FV in caries prevention efficacy of FPMs at 2 years' follow-up, emphasizing the use of FV since it is more affordable and easier to apply.

Knowledge, beliefs, attitude, and practices of E-cigarette use among dental students: A multinational survey.

BACKGROUND: E-cigarette use is a trend worldwide nowadays with mounting evidence on associated morbidities and mortality. Dentists can modify the smoking behaviors of their patients. This study aimed to explore the knowledge, beliefs, attitude, and practice of E-cigarette use among dental students. MATERIALS AND METHODS: This multinational, cross-sectional, questionnaire-based study recruited undergraduate dental students from 20 dental schools in 11 countries. The outcome variable was current smoking status (non-smoker, E-cigarette user only, tobacco cigarette smoker only, dual user). The explanatory variables were country of residence, sex, age, marital status, and educational level. Multiple linear regression analysis was performed to explore the explanatory variables associated with E-cigarette smoking. RESULTS: Of the 5697 study participants, 5156 (90.8%) had heard about E-cigarette, and social media was the most reported source of information for 33.2% of the participants. For the 5676 current users of E-cigarette and/or tobacco smoking, 4.5% use E-cigarette, and 4.6% were dual users. There were significant associations between knowledge and country (P< 0.05), educational level (B = 0.12; 95% CI: 0.02, 0.21; P = 0.016) and smoking status (P< 0.05). The country of residence (P< 0.05) and smoking status (P< 0.05) were the only statistically significant factors associated with current smoking status. Similarly, there were statistically significant associations between attitude and country (P< 0.05 for one country only compared to the reference) and history of previous E-cigarette exposure (B = -0.52; 95% CI: -0.91, -0.13; P = 0.009). Also, the practice of E-cigarettes was significantly associated with country (P< 0.05 for two countries only compared to the reference) and gender (B = -0.33; 95% CI: -0.52, -0.13; P = 0.001). CONCLUSION: The knowledge of dental students about E-cigarette was unsatisfactory, yet their beliefs and attitudes were acceptable. Topics about E-cigarette should be implemented in the dental curriculum.

Prevalence of Caries among School Children in Saudi Arabia: A Meta-Analysis.

Introduction: Children's dental health has become the primary concern, because of the increase in the prevalence of caries amongst school children in Saudi Arabia. Therefore, a meta-analysis was conducted to assess the prevalence and severity of dental caries among school children in Saudi Arabia. Method: A systematic search of Scopus, ISI Web of Science, EMBASE, Saudi digital library, Google Scholar, and MEDLINE via Ovid for cross-sectional studies with healthy participants between 5and -15 years. Two authors independently extracted the prevalence of caries. With 95% confidence intervals (CIs) using a random-effects model, we calculated caries prevalence. Results: Dental caries prevalence data were extracted from 18 cross-sectional studies (n = 56,327 children). The pooled estimate for the caries prevalence among 5-7 years' children was 84% (95% CI: 0.81-0.87%; I2 = 91%) while among 12-15 years' children was 72% (95% CI: 0.63-0.79; I 2 = 96.2%). Discussion. In this systematic review, the summary estimate of the prevalence of dental caries among children of 5-7 years and 12-15 years were 84% and 72%, respectively. Further research is required to identify approaches for preventing and treating dental caries in schoolchildren.

Minocycline incorporated cobalt oxide nanoparticles in dental sealants: An in vitro study.

The purpose of this study was to introduce antibacterial property to pits and fissure sealant (PFS) in order to mitigate the major clinical problems associated with PFS, such as microleakage and secondary caries. We prepared a pH reliant cobalt oxide nanoparticle incorporated with minocycline (MNC@CO) and characterized to investigate its antibacterial potential against Streptococcus sobrinus. The physiochemical, morphological, and drug release kinetics at different pH (7.4, 5.0, and 3.5) from nanoparticles were investigated. The MNC@CO were added at 2.5% and 5.0% into experimental PFS and characterized for their antibiofilm capacity, biocompatibility, and mechanical properties including compressive and flexural strength. The groups 2.5% and 5.0% has shown statistically significant antimicrobial capacity against S. sobrinus compared to control (p < .05). The highest percentage of MNC release at different pH (especially at pH 5.0 and 3.5) was observed from 5.0% MNC@CO doped PFS. The PFS doped with 2.5% MNC@CO showed a highest compressive strength (110 MPa) over a period of 70 days as compared to 5.0% MNC@CO (75 MPa) and control (80 MPa). The flexural strength of both experimental groups was lower for both time points (24 h and 30 days) than control. In conclusion, the present study found that 2.5% MNC@CO doped PFS showed considerable anti-biofilm potential without compromising mechanical properties.

Oral health practices and self-reported adverse effects of E-cigarette use among dental students in 11 countries: an online survey.

OBJECTIVES: E-cigarette use has become popular, particularly among the youth. Its use is associated with harmful general and oral health consequences. This survey aimed to assess self-reported oral hygiene practices, oral and general health events, and changes in physiological functions (including physical status, smell, taste, breathing, appetite, etc.) due to E-cigarette use among dental students. METHODS: This online, multicounty survey involved undergraduate dental students from 20 dental schools across 11 different countries. The questionnaire included demographic characteristics, E-cigarette practices, self-reported complaints, and associated physiological changes due to E-cigarette smoking. Data were descriptively presented as frequencies and percentages. A Chi-square test was used to assess the potential associations between the study group and sub-groups with the different factors. Statistical analysis was performed using SPSS at P < 0.05. RESULTS: Most respondents reported regular brushing of their teeth, whereas only 70% used additional oral hygiene aids. Reported frequencies of complaints ranged from as low as 3.3% for tongue inflammation to as high as 53.3% for headache, with significant differences between E-cigarette users and non-users. Compared to non-smokers, E-cigarette users reported significantly higher prevalence of dry mouth (33.1% vs. 23.4%; P < 0.001), black tongue (5.9% vs. 2.8%; P = 0.002), and heart palpitation (26.3%% vs. 22.8%; P = 0.001). Although two-thirds of the sample reported no change in their physiological functions, E-cigarette users reported significant improvement in their physiological functions compared to never smokers or tobacco users. CONCLUSION: Dental students showed good oral hygiene practices, but E-cigarette users showed a higher prevalence of health complications.

Perception of orofacial appearance among laypersons with diverse social and demographic status.

BACKGROUND: The perception of dentofacial esthetics differs considerably between patients and dentists. Patient's expectations regarding his/her esthetics are important and should be assessed ahead of any planning of esthetic treatment. The aim of this study was to explore the differences in perception of orofacial appearance by laypersons with different social and demographic status. MATERIALS AND METHODS: Self-administered questionnaires were distributed to 400 subjects. The questionnaire comprised three parts; the first part addressed the demographic variables. The second part queried about dental prosthesis, orthognathic or plastic surgery, and/or ongoing or previous orthodontic treatment. The third part included the Arabic version of the-8-item Orofacial Esthetic Scale (OES-Ar) whose responses were scored in the 5-point Likert scale. These scores were compared by different grouping factors (age, gender, marital status, and education) using non-parametric Mann-Whitney U and Kruskal Willis tests with 95% confidence interval (α > 0.05). RESULTS: A total of 268 questionnaires were eligible for analysis, representing 67% response rate. The satisfaction with facial profile appearance was the highest (4.0±1.1) followed by facial appearance (3.9±1.1), while the color of teeth was the least satisfying item (3.1±1.3). No significant differences were found between age groups for the mean summary score as well as for each item independently. No significant difference was found between both sexes except for the last item "overall impression". Married subjects rated one item (alignment of teeth) better than their counterparts. Positive perception of orofacial appearance increased significantly with the increase of education level, the perception of the oral health status, and the perception of the general health status. CONCLUSION: Good oral health and/or high education level are significant determinants of more positive perception of orofacial esthetic appearance. Patients with these characteristics might be more concerned about their orofacial appearance, and this should be taken into consideration before planning any esthetic restorative dental treatment.

Happiness among dentists: a multi-scale, multi-national study from 21 countries.

OBJECTIVES: The extent to which dentists are happy with their profession and their life has not been well studied. The present study aimed to explore the level of happiness, satisfaction with life and psychological well-being among a sample of dental professionals from 21 countries. MATERIALS AND METHODS: The sample comprised 2,200 dentists from 21 countries. Three scales - Subjective Happiness Scale (SHS), Satisfaction With Life Scale (SWLS), and Affect Balance Scale (ABS) - were used to measure the subjective responses. Data related to demographic and social characteristics were recorded. Mann-Whitney and Kruskal-Wallis tests were used as appropriate. Scales were correlated, and multiple linear regression analyses were employed to identify the independent determinants of SHS, SWLS and ABS. Data were analysed using the SPSS software program; a value of P <0.05 was considered significant. RESULTS: The overall mean scores of SHS, SWLS and ABS were 18.53 ± 5.06, 23.06 ± 6.25 and 1.26 ± 2.40, respectively, with significant differences found across countries: dentists working in Croatia, Peru and Serbia recorded the highest scores, unlike dentists practicing in Yemen, Syria, and Iraq, who recorded the lowest scores. There were significant, moderately positive correlations between the various scales: SHS and SWLS: r = 0.535, P < 0.001; SHS and ABS: r = 0.58, P < 0.001; and SWLS and ABS: r = 0.533, P < 0.001. Country of practice, age, qualification and monthly income were the significant independent predictors of SHS, SWLS and ABS. CONCLUSION: Country of residence and social characteristics were associated with dentists' responses regarding their feelings and subjective well-being.

An audit of root canal filling quality performed by undergraduate pre-clinical dental students, Yemen.

BACKGROUND: Dental students are future dentists. Continuous assessment and improving of the educational curricula will ensure excellent academic performance of dental students and thus providing the community with the best treatment modalities. The aim of this study was to evaluate the root canal filling quality performed in extracted teeth by preclinical undergraduate Yemeni dental students. METHODS: Root canal treatment was performed by undergraduate preclinical dental students on 331 extracted human teeth including 741 roots. The teeth were then collected and evaluated radiographically based on three criteria of quality (length, density, and taper). Cohen's Kappa test was used to assess the agreement between the examiners and Chi-squared test was used for the association between the study variables. The level of significant was set at α < 0.05. RESULTS: The results of the study revealed that the overall quality of roots canals fillings was poor. However, more than half of the study sample (53.4%) had adequate length, 13.1% had adequate density, and 14.2% had adequate taper. Anterior as well as single-rooted teeth had significantly better quality than posterior and multi-rooted teeth, respectively. The root canal fillings quality mandibular teeth was better than of maxillary teeth with no significant difference (P > 0.05). CONCLUSION: The findings of the study emphasize the need of improving the endodontic course in the preclinical level and more advanced techniques and instruments should be incorporated.

Link between perceived oral and general health status among Yemeni adult dental patients.

BACKGROUND: Self-perceived health is an essential measure of health status and even a paramount predictor of mortality. So long as it is said that oral health (OH) and general health (GH) are mirrors to each other. This study sought to determine how Yemeni adults rate their OH and GH, whether such a self-rating influenced by some potential risk factors, and whether both ratings (OH and GH) are correlated. METHODS: A sample of 587 Yemeni dental patients aged 20 years and over were consecutively recruited. A structured interview form was used covering the following variables: age, gender, marital status, educational level, presence of dental prosthesis (DP), smoking and Qat chewing habits as independent variables, along with questions on "perceived oral health (POH)" and "perceived general health (PGH)" as dependent variables. The bivariate and multiple ordinal regression analyses were applied at P-value < 0.05. RESULTS: Most of participants were women (73.6%), and married (71.4%), and more than half of them were young adults (58.2%), with high educational levels (53.3%), and not having DP. Only 310 participants responded to the questions on smoking and Qat chewing habits. Of these, 88.5% were non-smokers and 62.1% were Qat non-chewers. Up to 50% of the participants reported their POH as poor or fair, while lower proportions of participants (17%) reported their PGH as such. Younger age (compared to elders), high education levels (compared to primary education) and being single (compared to married) significantly revealed better levels of POH, while high education levels and being females significantly revealed better levels of PGH. Smoking and Qat chewing habits were found to have no effect on the perception of POH or PGH. POH and PGH were found to be significantly correlated (r = 0.486; P < 0.001). CONCLUSION: Higher levels of oral health problems can be anticipated among patients who perceive poor general health, and vice versa. The age, marital status and education were independent determinants of POH, while the gender and education were independent determinants of PGH.

Experimental and theoretical insights on the effect of solvent polarity on the photophysical properties of a benzanthrone dye.

Benzanthrone derivatives show interesting solvent dependent photophysical properties. Understanding of their photophysical properties is essential for developing the fluorescence probes based on benzanthrone derivatives. The photophysical properties of 3-(N'-chlorophenyl)piperazino-7H-benzo[de]anthracen-7-one [ClPh-PBA] molecule are reported in different solvents and solvent mixtures. The change in Stokes shift, quantum yield, fluorescence life time and radiative rate constants as a function of solvent polarity shows that the Intermolecular Charge Transfer (ICT) is affected by solvent polarity and hydrogen bonding. The quantum yield and fluorescence life time values decrease and the nonradiative decay rate constant (knr) values are observed to be higher in polar solvents. The weak emission of ClPh-PBA in polar solvents is primarily due to the non-radiative torsional motion of the chlorophenyl group around benzanthrone moiety. The torsional motion of chlorophenyl group at the remote nitrogen around benzanthrone moiety is also evident from TDDFT calculations performed using B3LYP/6-311+ G (d, p) basis set. The ground state and excited state dipole moments, absorption and emission maxima (nm) along with other quantum chemical parameters are obtained using B3LYP/6-311+ G (d, p) basis set. The experimental and theoretical results follow the similar trends.

Understanding the interaction of carbon quantum dots with CuO and Cu2O by fluorescence quenching.

In spite copper oxide being one of the essential micronutrient, copper oxide in its nano size is found to be toxic in nature; this instigates for the detection of copper oxides in trace levels. In the present study, we demonstrate simple cost effective detection method for CuO/Cu2O using carbon quantum dots (CQD) by fluorescence quenching technique. CuO/Cu2O nanoparticles are synthesised by mere variation of fuel ratio by solution combustion technique. The resulting oxides are characterized by various analytical and spectroscopic techniques. Powder X- ray diffraction (PXRD) results reveals that samples prepared with oxidizer to fuel (O/F) ratios 1:1, 1:1.5 and 1:2 showed pure nano CuO, major CuO phase (minor Cu2O) and major Cu2O phase (minor CuO) respectively. Further, the samples prepared using 1:1 O/F ratio and calcinated at 700 °C showed highly crystalline CuO phase. In order to study the interaction of CuO/ Cu2O with CQDs the fluorescence quenching method has been employed. The bimolecular quenching rate constants for the samples prepared with different O/F ratios have been measured. The interaction between CQDs and copper oxides, indicates fluorescence quenching greatly depends on the oxidation state of the copper oxide and can be a promising method for detecting CuO/Cu2O through CQDs.

Creep Behavior of Resin Composite Interface Between Orthodontic Brackets and Enamel.

PURPOSE: The present study investigated the creep of adhesive resin under constant loading at the orthodontic bracket/enamel interface with an orthodontic bracket-tooth model (shear creep) and three-point bending test (bending creep). MATERIALS AND METHODS: For the bracket-tooth model, sixty premolars were assigned to 4 groups (n = 15). Orthodontic brackets were bonded onto the enamel surface using four different bonding agents: conventional, homogeneous Transbond XT orthodontic composite (group 1/TBC); Transbond XT composite reinforced with photopolymerized glass-fiber-reinforced composite (FRC with bidirectional fibers) (group 2/TBE); Transbond XT reinforced with FRC of vertically oriented unidirectional fibers (group 3/TBV); and Transbond XT reinforced with FRC of horizontally oriented fibers (group 4/TBH). Load was applied at the bracket/tooth interface and from the bracket wire slot. In the three-point bending test, the creep and recovery of the rectangular interface materials were tested by a dynamic mechanical analyzer. The data obtained were statistically analyzed with ANOVA and a post-hoc test using SPSS v20 statistical software. RESULTS: The groups exhibited significant differences in strain % and time for bracket deflection at the interface (p < 0.05). The interface loading with unidirectional fibers (groups TBV and TBH) were statistically significantly different compared to the interface with bidirectional fibers and control group (groups TBE and TBC). The three-point test showed the least creep compliance (ie, creep deformation occurring at each time point [J]) with group TBC, followed by groups TBV and TBE. Group TBC showed the highest nanohardness and elastic modulus; the lowest values were seen in group TBE, reflecting differences in polymer matrix composition. CONCLUSION: The creep and time for debonding the bracket increased with incorporation of glass fibers at the interface between bracket and enamel.

From body-on-frame to unibody constructions and designs mimicking biological structures - an overview.

In dentistry, isotropic materials, such as metals, ceramics, and polymers, are used. Their properties are not related to any specific direction of the material microstructure. There is a trend toward non-metallic, adhesive, and minimally invasive dentistry. This is in line with the conceptual change seen in the automobile industry, in which the basis of car structures has changed from body-on-frame designs to unibody designs. In unibody designs, all structural parts of the body of the car mechanically form a single structural entity. In modern adhesive dentistry, remaining tooth substance and the dental material form unibody designs, enabling preservation of tooth substance. Biological structures are created to withstand loading and are light in weight. The structural designs of elements in these biological materials are, to a large extent, based on fibrous material. More attention has been paid to mimicking fibrous structures of dental hard tissues by synthetic fiber-reinforced composites. This overview reports key features of natural fibrous elements and how they are utilized in dentistry. Special emphasis is placed on the aspects of interfacial adhesion of restorative materials, especially ceramics to resin-based materials and their role in the unibody design of the tooth-restoration system.

Degree of conversion and depth of cure of Ivocerin containing photo-polymerized resin luting cement in comparison to conventional luting agents.

OBJECTIVE: To evaluate the degree of conversion (DC) and depth (extent) of cure of four resin cements (Variolink E, Calibra, NX3 and Variolink N) using Fourier transform infrared (FTIR) and Vickers Micro hardness (MH). METHODS: Ten disks (1mmx2mm) of each resin cement were light cured through a ceramic disk for 40 seconds prior to assessment. The ATR spectra of the uncured resin were collected in absorbance mode from 16 scans at 4 wave number resolutions. Degree of conversion was calculated by estimating the changes in peak height ratio of the absorbance intensities of aliphatic C=C peak at 1638 cm-1 and that of an internal standard peak of aromatic C=C at 1608 cm-1 during polymerization. For Vickers microhardness testing 10 disks of each cement specimen was exposed to 100 grams of load for 15 seconds. Three indentations were made 0.5mm apart and an average Vickers micro-hardness (MH) for each specimen. Two way ANOVA and multiple comparison tests were performed to assess data. RESULTS: The highest degree of conversion by peak area was shown by Variolink-Esthetic [light-cure (87.18±2.90%)]; however the lowest was observed in samples of Variolink-N [Dual cure (44.55±4.33%)]. Similarly, Variolink-Esthetic and NX3 cement showed significantly higher MH as compared to other groups. CONCLUSION: Ivocerin containing Variolink-E cement showed high degree of conversion and extent of polymerization when compared to conventional light and dual cure luting cements.

Effect of Er,Cr:YSGG Laser and Ascorbic Acid on the Bond Strength and Microleakage of Bleached Enamel Surface.

BACKGROUND: The available evidence of Er,Cr:YSGG lasers on bleached enamel is limited and controversial. It is assumed that Er,Cr:YSGG laser will be effective in reversing the effect of bleaching on adhesive bond integrity of enamel to resin composite. OBJECTIVE: The study aimed to evaluate the efficacy of Er,Cr:YSGG laser on bond strength and microleakage of bleached enamel. MATERIALS AND METHODS: From the 80 samples, 60 samples were bleached (40% hydrogen peroxide) and divided into three subgroups. Twenty bleached samples in each subgroup were exposed to 10% sodium ascorbate (Gp A), Er,Cr:YSGG laser (50 Hz and 4.5 W) (Gp L), and no treatment (Gp B), respectively. Twenty samples were not bleached (Control-C). Using etch and rinse technique, resin composite was built-up on enamel and photopolymerized. Ten specimens in each group were tested for shear bond strength at a crosshead speed of 1 mm/min. Ten specimens in each group were tested for microleakage using 2% methylene blue. Data were analyzed using analysis of variance (ANOVA) and Tukey post hoc multiple comparisons test. RESULTS: The mean bond strength of specimens in group L (30.83 ± 1.7000) was comparable with group A (31.38 ± 2.03) and was significantly higher than bleached specimens (9.49 ± 0.86) (p < 0.001). The highest mean microleakage values were observed in bleached group (630.32 ± 156.58). The mean microleakage among control (36.66 ± 27.33) and laser group specimens (55.32 ± 34.98) was comparable (p > 0.05). CONCLUSIONS: Treatment of bleached enamel with erbium, chromium:yttrium-scandium-gallium-garnet (Er,Cr:YSGG) laser showed a significant reversal effect on the enamel bond strength and microleakage scores. CLINICAL SIGNIFICANCE: Er,Cr:YSGG laser (50 Hz, 4.5 W) treatment has the potential to restore the bond strength of bleached enamel to resin composite.

Photophysical properties of benzanthrone derivatives: effect of substituent, solvent polarity and hydrogen bonding.

Benzanthrone derivatives are potential fluorescent probes for various chemical and biological environments. A mechanistic understanding of their photophysical properties is pivotal for designing an efficient fluorescence sensor based on the benzanthrone framework. In this study, we report on the effect of chemical substitution on the photophysical properties of two benzanthrone derivatives, namely, 3-(N'-methyl)-piperazino-7H-benzo[de]anthracen-7-one [Me-PBA] and 3-(N'-phenyl)-piperazino-7H-benzo[de]anthracen-7-one [Ph-PBA] in different solvents and solvent mixtures of varying polarities and proticities. Both benzanthrone derivatives show interesting solvent-dependent photophysical properties. Although both derivatives exhibit strong intramolecular charge transfer (ICT) characteristics in the excited state, the extent of the charge transfer is significantly influenced by the nature of the chemical substitution. Modulation of photophysical parameters as a function of solvent properties led us to propose that ICT is affected by solvent polarity and hydrogen bonding. From the viscosity effect, it is revealed that the weaker emission of Ph-PBA compared to Me-PBA in polar solvents is primarily due to the non-radiative torsional motion of the phenyl group in the former derivative. In protic solvents, intermolecular hydrogen bonding imparts strong non-radiative deactivation to both derivatives, thus rendering a weak fluorescence yield.

Green and Cost Effective Synthesis of Fluorescent Carbon Quantum Dots for Dopamine Detection.

Carbon quantum dots (CQDs) due to its high fluorescent output is evolving as novel sensing material and is considered as future building blocks for nano sensing devices. Hence, in this investigation we report microwave assisted preparation and multi sensing application of CQDs. The microwave derived CQDs are characterized by Dynamic Light Scattering (DLS) experiment and Fourier Infrared spectra (FTIR) to investigate the size distribution and chemical purity respectively. Fluorescent emission spectra recorded at varying pH shows varying fluorescence emission intensities. Further, emission spectra recorded at different temperatures shows that fluorescence emission of CQDs greatly depends on temperature. Therefore, we demonstrate the pH and temperature sensing characteristics of CQDs by fluorescence quenching behaviour. In addition, the interaction and sensing behaviour of CQDs for dopamine is also presented in this work with a detection limit of 0.2 mM. The steady state and time-resolved methods have been employed in fluorescence quenching methods for sensing dopamine through CQDs at room temperature. The bimolecular quenching rate constants for different concentration have been measured. The interaction between CQDs and dopamine indicates fluorescence quenching method is an elegant process for detecting dopamine through CQDs.

Enhanced antimicrobial activity of naturally derived bioactive molecule chitosan conjugated silver nanoparticle against dental implant pathogens.

Various metal coated implants have been tested against dental pathogens which causes increased biofilm formation and lead to failure of dental implants. The possibility of using nanoparticle together with native biomolecules to enhance the activity of such bioactive compound is also in progress. In this study we tested the efficacy of Ag conjugated chitosan nanoparticles as a prospective coating material of titanium dental implants. Known bioactive molecule chitosan was extracted from A. flavus Af09 and conjugated with Ag nanoparticle. Fully characterized Ag-chitosan nanoparticle had a sound inhibitory effect on the growth of two major dental pathogens S. mutans and P. gingivalis. It not only inhibits the adhesion of these two tested bacteria but also able to reduce the biofilm formation. Apart from this, nanoparticle was also able to inhibit the QS production in bacteria tested in this study. Naturally extracted chitosan has been known for its antibacterial activity for a different group of bacteria. Nanoparticles are the good option to enhance the biocompatibility. No cell cytotoxicity of nanoparticle indicates its biocompatibility and coating of titanium dental implants with Ag-chitosan may have an added advantage on the corrosion resistance of dental implants and also augments the passivating effect of these implants.