Evidence of electron correlation and weak bulk plasmon in SrMoO3

We investigate the electronic structure of highly conducting perovskite SrMoO₃using valence band photoemission spectroscopy and electronic structure calculations. Large intensity corresponding to coherent feature close to Fermi level is captured by density functional theory (DFT) calculation. An additional satellite at ∼3 eV binding energy remains absent in DFT, hybrid functional (DFT-hybrid) and dynamical mean field theory (DFT + DMFT) calculations. Mo 4dspectra obtained with different surface sensitive photoemission spectroscopy suggest different surface and bulk electronic structures. DFT + DMFT spectral function is in excellent agreement with the coherent feature in the bulk Mo 4dspectra, revealing moderate electron correlation strength. A large plasmon satellite and signature of strong electron correlation are observed in the surface spectra, while the bulk spectra exhibits aweakplasmon satellite.

Revelation of Mott insulating state in layered honeycomb lattice Li2RuO3

We investigate the role of electron correlation in the electronic structure of honeycomb lattice Li₂RuO₃using photoemission spectroscopy and band structure calculations. Monoclinic Li₂RuO₃having Ru network as honeycomb lattice undergoes magneto-structural transition atT_c∼ 540 K from high temperature phaseC2/mto low temperature dimerized phaseP2₁/m. Room temperature valence band photoemission spectra reveal an insulating ground state with no intensity at Fermi level (E_F). Ru 4dband extracted from high and low photon energy valence band photoemission spectra reveal that the surface and bulk electronic structures are very similar in this system. Band structure calculations using generalized gradient approximation leads to metallic ground state while screened hybrid (YS-PBE0) functional reveals opening up of a gap in almost degenerated_zx/d_yzorbitals, whereasd_xyorbital is already gapped. Ru 3dcore level spectra with prominent unscreened feature provides direct evidence of strong electron correlation among Ru 4delectrons which is also manifested by |E-E_F|²dependence of spectral density of states in the vicinity ofE_Fin the high-resolution spectra, establishing Li₂RuO₃as Mott insulator.

Electronic structure of ternary palladates and effect of hole doping: a valence band photoemission spectroscopic study

We investigate the electronic structure of ternary palladatesAPd₃O₄(A= Sr, Ca) using valence band photoemission spectroscopy and band structure calculations. Energy positions of various features and overall width of the experimental valence band spectra are well captured by band structure calculations using hybrid functional. Band structure calculations within local density approximations lead to metallic ground state while the calculations using hybrid functional provide band gap of 0.25 eV and 0.22 eV for CaPd₃O₄and SrPd₃O₄respectively, suggesting moderate to strong electron correlation strength in these narrow band gap semiconducting palladates. High resolution spectra reveal negligibly small intensity at Fermi level,E_F, for parent compounds, while hole doped SrPd₃O₄(by 15% Li substitution at Sr site) exhibits a Fermi cut-off suggesting metallic character in contrast to semiconducting transport. These observations reveal the importance of localization of electrons in case where the Fermi edge falls in the mobility edge.

Electron-phonon coupling in APd3O4: A = Ca, Sr, and Sr0.85Li0.15

Here we have investigated the role of electron phonon coupling on the Raman spectrum of narrow bandgap semiconductors APd₃O₄ (A = Ca, Sr) and hole-doped system Sr_0.85Li_0.15Pd₃O₄. Four Raman active phonons are observed at room temperature for all three compounds as predicted by factor group analysis. The lowest energy phonon (∼190/202 cm^-1) associated with Pd vibrations is observed to exhibit an asymmetric Fano-like lineshape in all the three compounds, indicating the presence of an interaction between the phonon and the electronic continuum. The origin of the electronic continuum states and electron-phonon coupling are discussed based on our laser power- and temperature-dependent Raman results. We have observed an enhanced strength of electron-phonon coupling in Sr_0.85Li_0.15Pd₃O₄ at low temperatures which can be attributed to the metallicity in this doped compound.

Evaluation of platelet-rich fibrin and tricalcium phosphate bone graft in bone fill of intrabony defects using cone-beam computed tomography: A randomized clinical trial

Background:

Platelet-rich fibrin (PRF) is the second-generation platelet concentrate first described by Choukron et al. It incorporates leukocytes, platelets, and growth factors within dense fibrin matrix, can be used in periodontal regeneration alone or in combination with bone grafts.

Aim:

This study assesses bone fill in intrabony defects, following the use of β tricalcium phosphate (TCP) bone graft with and without PRF.

Materials and Methods:

Thirty sites with intrabony defects in periodontitis patients were selected, randomly allotted into three groups: Group A open flap debridement (OFD), Group B OFD with β TCP with PRF, and Group C β TCP. Clinical parameters such as plaque index, gingival index, sulcus bleeding index, and PPD recorded at baseline and 6 months. Radiographic parameters include cementoenamel junction (CEJ) to base of defect, CEJ to alveolar crest, depth of defect, and bone fill assessed using the cone-beam computed tomography (CBCT). The comparison between the test group and control group in terms of clinical and radiographical parameters was assessed using the independent sample t-test.

Results:

Significant reduction in probing depth measurements, defect fill observed in both β TCP with PRF and β TCP alone groups compared to OFD. However, intergroup comparison assessed using the independent sample t-test found to be statistically nonsignificant (P < 0.05 is considered significant).

Conclusion:

All three treatment strategies resulted in significant reduction in probing depth and bone fill at 6 months. Bone fill achieved in β TCP with PRF was more compared to β TCP alone and OFD at 6 months follow-up. CBCT can be accurately used to assess the morphology of intrabony defect and also in evaluating bone fill.

Efficacy of a Novel Zn-Substituted Monetite-Based Scaffold in the Treatment of Periodontal Osseous Defects

PURPOSE

The objective of this study was to evaluate the efficacy of a zinc-substituted nanostructured monetite-based scaffold (Sil-Oss®) in the treatment of periodontal intra-bony osseous defects.

METHODS

Thirty subjects participated in this study. Two sites in each subject were randomly assigned into each of the following experimental groups: Test group - open flap debridement (OFD) with Sil-Oss®; and control group - OFD with hydroxyapatite (HA) bone graft. Recorded clinical parameters included site-specific measures of plaque, probing pocket depth (PPD) and clinical attachment loss (CAL) at baseline, 3, 6 and 9 months. The evaluation of bone fill was performed by using digital subtraction technique and morphometric area analysis using two image processing software. Histological evaluation was done after 7 months by taking bone biopsy samples during crown lengthening procedures. Ten regions of interest (ROIs) per slide were visualized for mineralized tissue volume using an Olympus BX53® microscope at 40X magnification.

RESULTS

Sil-Oss® showed a significantly greater bone fill compared to HA at 3 and 6 months. Sil-Oss®-treated defects also showed a marked increase in the percentage of tissue mineralization (25.38% vs 23.73%) compared to HA-treated defects. No significant differences were observed between the two groups for CAL and PPD at 6 months.

CONCLUSION

We conclude from this trial conducted over a period of 9 months that Sil-Oss® has the potential to function as a graft material for periodontal regeneration.

Effect of a single session of antimicrobial photodynamic therapy using indocyanine green in the treatment of chronic periodontitis: a randomized controlled pilot trial

OBJECTIVE

The aim of this randomized controlled pilot study was to evaluate the effects of indocyanine green (ICG) as an adjunct to nonsurgical periodontal therapy in terms of reduction in percentage of viable bacteria and host tissue injury.

METHOD AND MATERIALS

The study included a small cohort of 30 subjects diagnosed with chronic periodontitis. Three sites from three different quadrants were selected and were randomly treated by (1) scaling and root planing (SRP), (2) SRP with application of 810 nm diode laser, or (3) SRP with application of 810 nm diode laser and ICG at a concentration of 5 mg/ mL. Primary parameters included estimation of viable bacteria percentage and lactate dehydrogenase (LDH) levels. Secondary parameters included site-specific measures of plaque, gingivitis, pocket depth (PD), and clinical attachment loss (CAL) at specific time intervals.

RESULTS

Sites receiving laser and ICG resulted in a significant decrease in the percentage of viable bacteria at the end of 1 week when compared to the other groups. ICG application does not seem to cause tissue damage as evident by the LDH levels. Comparison of CAL and PD revealed nonsignificant differences in sites treated with laser and ICG at the end of the study period.

CONCLUSION

Laseractivated ICG dye may enhance the potential benefits of SRP and can be used as an adjunct to nonsurgical periodontal therapy.

Possible Association Between the Mallampati Score of the Oropharynx and Measures of Tongue Coating, Oral Hygiene and Periodontal Status

PURPOSE

To assess oral hygiene and the gingival and periodontal disease status in subjects scored under the modified Mallampati classification (MMC) of the oropharynx.

PATIENTS AND METHODS

The clinical parameters included recording MMC scores, simplified oral hygiene index (OHI-S), modified gingival index (MGI), tongue coating index (TCI) and periodontal status of the subjects. Eight additional parameters, which included percentage of sites with bleeding on probing (BOP), sites with probing depth (PD) ≥ 5 mm, tooth loss, attachment loss (AL):age ratio, diabetic status, smoking, the interplay of dental status and systemic factors (DS-SFI), and background characteristics (socioeconomic status and stress) were also assessed.

RESULTS

Class IV MMC group showed the highest mean scores for OHI-S, periodontal status, AL:age ratio, diabetic status, background characteristics, PD ≥ 5 mm and DS-SFI when compared to other groups. In measures of OHI-S, periodontal status, PD > 5 mm, AL:age ratio and background characteristics, Class IV MMC group showed significant intergroup differences over MMC class I. Regression analysis revealed a highly significant but low degree of correlation (R2 = 0.079; p ≤ 0.001) between the predictors and the dependent values.

CONCLUSION

The results suggest that increasing MMC scores can be a possible determinant in identifying gingival and periodontal disease. Any dental professional dealing with a multifactorial disease such as periodontitis can use this classification as a basic screening tool in identifying the modifiable factors of periodontitis.

Identical mitochondrial somatic mutations unique to chronic periodontitis and coronary artery disease

Context:

The inflammatory processes involved in chronic periodontitis and coronary artery diseases (CADs) are similar and produce reactive oxygen species that may result in similar somatic mutations in mitochondrial deoxyribonucleic acid (mtDNA).

Aims:

The aims of the present study were to identify somatic mtDNA mutations in periodontal and cardiac tissues from subjects undergoing coronary artery bypass surgery and determine what fraction was identical and unique to these tissues.

Settings and Design:

The study population consisted of 30 chronic periodontitis subjects who underwent coronary artery surgery after an angiogram had indicated CAD.

Materials and Methods:

Gingival tissue samples were taken from the site with deepest probing depth; coronary artery tissue samples were taken during the coronary artery bypass grafting procedures, and blood samples were drawn during this surgical procedure. These samples were stored under aseptic conditions and later transported for mtDNA analysis.

Statistical Analysis Used:

Complete mtDNA sequences were obtained and aligned with the revised Cambridge reference sequence (NC_012920) using sequence analysis and auto assembler tools.

Results:

Among the complete mtDNA sequences, a total of 162 variations were spread across the whole mitochondrial genome and present only in the coronary artery and the gingival tissue samples but not in the blood samples. Among the 162 variations, 12 were novel and four of the 12 novel variations were found in mitochondrial NADH dehydrogenase subunit 5 complex I gene (33.3%).

Conclusions:

Analysis of mtDNA mutations indicated 162 variants unique to periodontitis and CAD. Of these, 12 were novel and may have resulted from destructive oxidative forces common to these two diseases.

Evaluation of the Antibacterial Effect of Silver Nanoparticles on Guided Tissue Regeneration Membrane Colonization--An in Vitro Study

OBJECTIVE

The aim of this in vitro study was to investigate the colonization and penetration of specific bacteria on nanosilver-impregnated GTR (guided tissue regeneration) membranes.

METHODS

Three sets of GTR membranes were used in this study: 1) GTR-C: Plain GTR membrane as a negative control; 2) GTR-NS: GTR membrane impregnated with silver nanoparticles as the test group; 3) GTR-DOX: GTR membrane impregnated with 25% (w/w) doxycycline hydrochloride acting as a positive control. Stress-strain characteristics were calculated to determine the physical properties of the control and impregnated membranes. Qualitative observation of microbial adherence and bacterial penetration through GTR membranes were performed by using four organisms (Streptococcus mutans, Aggregatibacter actinomycetemcomitans, Fusobacterium nucleatum and Porphyromonas gingivalis) reported to have strong adherent capabilities to collagen membranes.

RESULTS

The mean bacterial adherence scores were significantly greater (p < 0.001) in the GTR-C group when compared to GTR-DOX and GTR-NS groups. GTR-NS showed lower adherence scores than GTR-DOX across all four microorganisms; this difference, however was not statistically significant. The difference in colony forming units (CFUs) was highly significant (p < 0.001), suggesting greater penetration in GTR-C membranes when compared to GTR-NS and GTR-DOX groups. Though the mean CFUs were lower in GTR-DOX than in GTR-NS across all four microorganisms, this difference was statistically significant only for S. mutans and F. nucleatum.

CONCLUSION

The incorporation of silver nanoparticles may be of value when controlling membrane-associated infection. Studies with different nanosilver particle sizes should be conducted to further evaluate the beneficial properties of nanosilver against periodontal pathogens.

Evaluation of clinical, antiinflammatory and antiinfective properties of amniotic membrane used for guided tissue regeneration: A randomized controlled trial

BACKGROUND

The objective of this study was to evaluate the antiinflammatory, antiinfective and clinical properties of amniotic membrane (AM) when used for guided tissue regeneration (GTR) in contained interdental defects.

MATERIALS AND METHODS

A total of 30 subjects participated in this study. Two sites in each subject were randomly assigned into each of the following experimental groups; test group: AM with bone graft and control group: Bone graft only. Clinical parameters included recording site-specific measures of plaque, gingivitis, probing pocket depth (PPD), and clinical attachment loss (CAL). The levels of interleukin-1β (IL-1β) and human beta-defensin-2 (hBD-2) levels in gingival crevicular fluid (GCF) from the test and control sites were measured by using commercially available enzyme linked immunosorbent assay kits. The evaluation of bone fill was performed by using digital subtraction technique and morphometric area analysis. One-way analysis of variance followed by the post-hoc test was used for intragroup and intergroup comparison. A P < 0.05 was considered as statistically significant.

RESULTS

Combination therapy using an AM increased bone fill and reduced PPD and CAL when compared to controls. AM also resulted in a significant reduction of GCF IL-1β levels and insignificant increase in the hBD-2 levels.

CONCLUSION

From this trial conducted over a period of 24 weeks, AM demonstrated a marked antiinflammatory effect and its use resulted in an improvement in periodontal parameters. AM has the potential to function as a barrier for GTR and the unique properties associated with this material can augment its potential as a matrix for periodontal regeneration.

Locally delivered antioxidant gel as an adjunct to nonsurgical therapy improves measures of oxidative stress and periodontal disease

Purpose

The present study has two aims; firstly, it attempts to verify the presence of oxidative stress by estimating the reactive oxygen species (ROS) levels in periodontal pockets ≥5 mm as compared to controls. The second aim is to evaluate the effect of lycopene as a locally delivered antioxidant gel on periodontal health and on the gingival crevicular fluid (GCF) levels of 8-hydroxydeoxyguanosine (8-OHdG), a marker of oxidative injury.

Methods

Thirty-one subjects participated in this study. In the pretreatment phase, the ROS levels in pockets ≥5 mm were measured by flow cytometry. Three sites in each subject were randomly assigned into each of the following experimental groups: sham group, only scaling and root planing (SRP) was done; placebo group, local delivery of placebo gel after SRP; and lycopene group, local delivery of lycopene gel after SRP. Clinical parameters included recording site-specific measures of GCF 8-OHdG, plaque, gingivitis, probing depth, and clinical attachment level.

Results

The gel, when delivered to the sites with oxidative stress, was effective in increasing clinical attachment and in reducing gingival inflammation, probing depth, and 8-OHdG levels as compared to the placebo and sham sites.

Conclusions

From this trial conducted over a period of 6 months, it was found that locally delivered lycopene seems to be effective in reducing the measures of oxidative stress and periodontal disease.

Analysis of association between TLR-4 Asp299Gly and Thr399Ile gene polymorphisms and chronic periodontitis in a sample of south Indian population

Background:

To analyze the association between TLR-4 Asp299Gly and Thr399Ile gene polymorphisms and chronic periodontitis in a sample of south Indian population.

Materials and Methods:

Genomic DNA was obtained from peripheral blood of 60 patients with chronic periodontitis and 60 periodontally healthy subjects. TLR-4 Asp299Gly and Thr399Ile gene polymorphisms were genotyped by a polymerase chain reaction–restriction fragment length polymorphism method. The data were analyzed by a χ²-test and by relative risk estimation.

Results:

Thr399Ile alleles were found in 4% of chronic periodontitis patients and in 1% of periodontally healthy subjects. The prevalence of a Thr399Ile heterozygote was found to be 5% in the chronic periodontitis group and 1.67% in the periodontally healthy group, respectively. Homozygosity for TLR-4 Thr399Ile was seen in chronic periodontitis patients only, which was 1.67%. The TLR-4 Asp299Gly gene polymorphism was not detected in either chronic periodontitis or periodontally healthy groups.

Conclusion:

There is no significant association between TLR-4 Thr399Ile polymorphism and chronic periodontitis in a sample of south Indian population.

Efficacy of lycopene as a locally delivered gel in the treatment of chronic periodontitis: smokers vs nonsmokers

OBJECTIVE

The present study was carried out as a multicenter, randomized controlled, split-mouth clinical trial to evaluate the efficacy of locally delivered lycopene on periodontal health and gingival crevicular fluid (GCF) levels of 8-hydroxydeoxyguanosine (8-OHdG) in smokers and nonsmokers compared with periodontally healthy control subjects.

METHOD AND MATERIALS

One hundred ten subjects including 50 smokers, 50 nonsmokers, and 10 controls participated in this study. Subjects in the smoker and nonsmoker groups had contralateral sites treated with lycopene gel and a placebo. Clinical parameters included recording site-specific measures of plaque, gingivitis, probing depth, and clinical attachment level. GCF 8-OHdG values were analyzed using a commercially available ELISA kit.

RESULTS

Compared with the placebo, lycopene-treated sites in smokers and nonsmokers showed significant reductions in probing depths and gain in the clinical attachment levels. However, there was no statistically significant difference in the clinical parameters when lycopene-treated sites in smokers and nonsmokers were compared, except for the reduction in the 8-OHdG levels. The 8-OHdG levels at 1 week and 3 months in sites treated with lycopene in the smoker and nonsmoker group were comparable with those in the periodontally healthy control group.

CONCLUSION

The gel formulation was effective in increasing clinical attachment and reducing gingival inflammation, probing depth, and oxidative injury compared with the placebo in smoking and nonsmoking subjects.

Where will the stem cells lead us? Prospects for dentistry in the 21 century

It is dentists’ dream to achieve bone repair with predictability, but without donor site morbidity as well as reconstruction of injured or pathologically damaged complex dental structures, however, this will no longer be a dream as these are being made into a reality using stem cell science. Stem cell science is clearly an intriguing and promising area of science. Stem cells have been isolated from a variety of embryonic and adult tissues. Dental stem cells are multipotent mesenchymal stem cells (MSCs) brought new enthusiasm among the researchers because of their easy accessibility, high quality and they don’t pose the same ethical concerns and controversy in comparison with embryonic stem cells. This review article provides brief insights about stem cell basics, the state of art in human dental stem cell research and its possible impact on future dentistry. Even though most of these modalities are still in infancy, it is evident that the 21^st century dentist is going to play a critical role in the field of medicine. The aim of this article is to bring awareness among the dentists about the huge potential associated with the use of stem cells in a clinical setting, as well as proper understanding of related problems.

Genomic diversity at thirteen short tandem repeat loci in a substructured caste population, Golla, of southern Andhra Pradesh, India

Genomic diversity based on 13 short tandem repeat (STR) loci was studied in seven population groups of a substructured Golla caste from Chittoor district in southern Andhra Pradesh, India. These groups are traditionally pastoral, culturally homogeneous, and strictly endogamous. Blood samples were drawn from 317 individuals from 30 Golla villages. The 13 STR loci analyzed in five standard multiplex polymerase chain reactions were: (1) CSF1R, TH01, and PLA2A; (2) F13A1, CYP19, and LPL; (3) D21S1446 and D21S1435; (4) D20S481, D20S473, and D20S604; and (5) D5S1453 and D6S1006. The average heterozygosity was found to be low among the Golla subgroups (0.64-0.70) in comparison to that of groups at the upper levels of the hierarchy. The coefficient of gene differentiation was found to be moderate (average GST = 0.031; range between 0.018 and 0.049 among the loci) when compared to that observed for a similar class of markers among populations with relatively higher levels of hierarchy, for example, among castes. It is, however, much higher when compared to the average observed for Indian caste and tribal populations, based on classical markers. Genetic distance measures revealed clusters of populations that are consistent with the known ethnohistorical and geographical backgrounds of the groups. We claim that these hypervariable markers are quite useful in understanding the process of substructuring within the Indian castes, leading to the formation of smaller breeding isolates, the basic Mendelian units within which microevolutionary forces operate.

Histomorphometric and biochemical correlates of arterial procollagen gene expression during vascular repair after experimental angioplasty

BACKGROUND

To determine the transcriptional, biochemical, and histomorphometric correlates of neointimal procollagen accumulation during arterial repair after balloon angioplasty of atherogenic vessels, rabbit iliac artery collagen content and the induction of alpha 1(I) and alpha 1(III) procollagen mRNA were assessed in normal vessels and at 2, 7, and 30 days after angioplasty.

METHODS AND RESULTS

Quantitative iliac artery histomorphometric neointimal collagen analysis was performed using a specific picrosirius red stain under polarized light. Arterial cross-sectional area reduction, total cellularity, and vascular smooth muscle cell density (per 10(4) mu2 of neointima) were quantified in routine and immunohistochemically stained sections (alpha-actin and RAM-11), from which biochemical concentrations of tissue protein, RNA, and DNA were also measured. Collagen comprised 0.23 +/- 0.1 mg/mg of total protein in the normal vessel wall and did not increase in vessels studied 2 and 7 days after angioplasty (0.26 +/- 0.06, 0.28 +/- 0.05 mg/mg of protein, P = NS). By 30 days after angioplasty, > 50% of the protein concentration was collagen (0.55 +/- 0.11 mg/mg of protein, P = .02). Collagen-positive histological staining also increased significantly from 17 +/- 2% of the neointima at day 2 to 32 +/- 5% by day 30 (P = .01). The transcript regulatory signal for alpha 1(I) procollagen mRNA was induced 2 days after angioplasty, peaking at 7 days for both alpha 1(I) and alpha 1(III), and returning to control levels 30 days after angioplasty. A significant luminal cross-sectional area reduction of the arterial wall was confirmed both by angiography and histomorphometry (P = .01). This was not associated with a significant change in alpha-actin (+) vascular smooth muscle cell density (38 +/- 7 nuclei per 10(4) mu2 at day 2 and at day 30) or tissue DNA concentration (P = NS).

CONCLUSIONS

We conclude that procollagen genes are transcriptionally activated early (2 to 7 days) after angioplasty vessel injury and that collagen subsequently constitutes a major biochemical and histological component of the proliferative neointima by 30 days after angioplasty. Alterations in pathways regulating procollagen metabolism may also contribute to the accumulation of extracellular matrix and growth of the neointima in the late repair phase after vessel wall injury.