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Background: The effect of different intracanal medicaments on root fracture resistance has not been thoroughly investigated in the short and long term. To assess the effect of calcium hydroxide (CH), CH combined with Chlorhexidine (CHX), double antibiotic paste (DAP), and simvastatin as intracanal medicaments on the fracture resistance of the human root. One hundred and twenty single-rooted mandibular premolars which were extracted for periodontal reasons were collected for this in vitro study., Materials and Methods: This was an in vitro study. All teeth were decoronated. Root canals were prepared by the Pro taper system, and %2.5 NaOCl was used for irrigation. The smear layer was removed using %5.25 NaOCl and 17% ethylenediaminetetraacetic acid each for 3 min. The samples were randomly divided into five groups based on the medicament: (1) CH (2) CH + CHX (3) Simvastatin (4) DAP (5) Control group. All specimens in each group were incubated for 1 week (Subgroup A) and 1 month (Subgroup B). Then, medicaments were removed and filled with gutta-percha and AH26 sealer. All samples were tested for fracture resistance. The data were statistically evaluated with the SPSS software 17. ANOVA and Mann-Whitney U and Wilcoxon tests were used for the analysis of the data. P = 0.05 was considered statistically significant., Results: Although CH and CH + CHX increased the fracture resistance in a 1-week period, there was no significant difference between the groups after 1 month., Conclusion: Under the limitations of this study, CH and CH + CHX, DAP and simvastatin do not have a negative effect on root fracture resistance when used as intracanal medicaments for <1 month., Competing Interests: The authors of this manuscript declare that they have no conflicts of interest, real or perceived, financial or non-financial in this article., (Copyright: © 2022 Dental Research Journal.)

Background: The aim of this in vitro study was to examine and compare the effect of photodynamic therapy and solution containing nano particles Ag/ZnO on adhesion of endodontic sealers to dentinal walls of human root canal., Material and Methods: Ninty single-rooted human teeth were selected and their clinical crown was cut from the cemento-enamel junction zone. Canals were prepared by RaCe rotary system and the smear layer was removed using 17% EDTA and 5.25% NaOCl. Samples were randomly divided into two groups of AH Plus and MTA Fillapex based on the sealer type and each group based on antimicrobial method was divided into two sub-groups of photodynamic therapy and polymer containing nano particles of Ag / ZnO and a control sub-group (N = 15). After obturation of canals with gutta-percha and sealers mentioned, the samples were incubated for a week at a humidity of 95% and 37°C and then 2mm thick discs were prepared from the middle region of roots for Push-out test. The maximum failure force was recorded in newton and converted to MPa. Then, 3 random specimens of each subgroup were evaluated by scanning electron microscopy. Statistical analysis was performed by Two way ANOVA and ( P <0.05) was considered significant., Results: The highest (4.84 ± 1.63) and lowest (0.16 ± 0.075) push-out bond strength values were obtained in (AH Plus-PDT) and (MTA Fillapex-Ag/ZnO) respectively. Independent of antimicrobial method, AH Plus bond strength was significantly higher than the MTA Fillapex ( p <0.001). For both sealers, PDT increased the bond strength significantly ( p <0.001)., Conclusions: Photodynamic therapy has a positive effect on the bond strength of AH Plus and MTA Fillapex sealers. Key words: AH Plus, MTA Fillapex, Nano particles, Photodynamic therapy, Push-out., Competing Interests: Conflict of interest statement:The authors declare they have no conflicts of interest.

Introduction: The aim of this in vitro study was to evaluate and compare the penetration depth of conventional (CH) and nano-particle calcium hydroxide (NCH) into dentinal tubules., Methods and Materials: Ninety human single-rooted teeth were instrumented by RaCe rotary system and after chemomechanical preparation were randomly divided in two equal groups ( n =45). In the first group conventional CH and in the other NCH was used as intracanal medicament. After 2 weeks of incubation all roots were intentionally split at longitudinal axis and prepared for scanning electron microscope (SEM) observation. Three zones of each root, coronal, middle and apical were examined under SEM and the maximum penetration depth of the dressing material into dentinal tubules was recorded for each zone. Data were analyzed using the independent sample t test and the level of significance was set at 0.05., Results: In all of the three zones, NCH group had greater penetration depth than CH ( P <0.001). In both groups the penetration depth increased from the apical section to the coronal., Conclusion: The depth of penetration of nano-particle calcium hydroxide into the dentinal tubules was significantly higher than that of conventional calcium hydroxide. The lowest penetration depth was observed in apical zone in both groups., Competing Interests: ‘None declared’.

The hitherto unexplored two-photon doubly excited states [Ne^{*}(2p^{-1}3s)]&#95;{2} were experimentally identified using the seeded, fully coherent, intense extreme ultraviolet free-electron laser FERMI. These states undergo ultrafast interatomic Coulombic decay (ICD), which predominantly produces singly ionized dimers. In order to obtain the rate of ICD, the resulting yield of Ne&#95;{2}^{+} ions was recorded as a function of delay between the extreme ultraviolet pump and UV probe laser pulses. The extracted lifetimes of the long-lived doubly excited states, 390(-130/+450)  fs, and of the short-lived ones, less than 150 fs, are in good agreement with ab initio quantum mechanical calculations.

Background. The aim of this study was to investigate myofibroblast (MF) density in a broad spectrum of odontogenic cysts and tumors and the relation between the density of MFs and the clinical behavior of these lesions. Methods. A total of 105 cases of odontogenic lesions, including unicystic ameloblastoma (UAM), solid ameloblastoma (SA), odontogenic keratocyst (OKC), dentigerous cyst (DC), radicular cyst (RC) (15 for each category), and odontogenic myxoma (OM), adenomatoid odontogenic tumor (AOT), calcifying odontogenic cyst (COC) (10 for each category), were immunohistochemically stained with anti-α-smooth muscle actin antibody. The mean percentage of positive cells in 10 high-power fields was considered as MF density for each case. Results. A statistically significant difference was observed in the mean scores between the study groups (P < 0.001). The intensity of MFs was significantly higher in odontogenic tumors compared to odontogenic cysts (P < 0.001). There was no statistically significant difference between odontogenic tumors, except between UAM and OM (P = 0.041). The difference between OKC and odontogenic tumors was not statistically significant (P > 0.05). The number of MFs was significantly higher in OKC and lower in COC compared to other odontogenic cysts (P = 0.007 and P = 0.045, respectively). Conclusion. The results of the present study suggest a role for MFs in the aggressive behavior of odontogenic lesions. MFs may represent an important target of therapy, especially for aggressive odontogenic lesions. Our findings support the classification of OKC in the category of odontogenic tumors.

The impact of the solvent on the photodissociation of embedded molecules has been intensively investigated in the last decades. Collisions of photofragments with the solvating atoms or molecules can change their kinetic energy distribution or even lead to the de-excitation of the dissociating molecule to a bound electronic state quenching the dissociation. In this article we show that this cage effect is strongly enhanced if interatomic Coulombic decay (ICD) of the excited state becomes allowed. Ab initio calculations in H2O-Cl(-) cluster show that the ultra-fast dissociation of water in the à excited state is strongly quenched by ICD. We found that this very efficient quenching is due to two factors. First, the lifetimes of the à state due to ICD are short ranging between 6 and 30 fs. Second, nuclear dynamics is dominated by the chattering motion of the H atom between O and Cl(-) allowing ICD to act for longer times. We hope that this work will be an important first step in clarifying the impact of ICD on photodissociation of embedded molecules.

When an excited atom is embedded into an environment, novel relaxation pathways can emerge that are absent for isolated atoms. A well-known example is interatomic Coulombic decay, where an excited atom relaxes by transferring its excess energy to another atom in the environment, leading to its ionization. Such processes have been observed in clusters ionized by extreme-ultraviolet and X-ray lasers. Here, we report on a correlated electronic decay process that occurs following nanoplasma formation and Rydberg atom generation in the ionization of clusters by intense, non-resonant infrared laser fields. Relaxation of the Rydberg states and transfer of the available electronic energy to adjacent electrons in Rydberg states or quasifree electrons in the expanding nanoplasma leaves a distinct signature in the electron kinetic energy spectrum. These so far unobserved electron-correlation-driven energy transfer processes may play a significant role in the response of any nano-scale system to intense laser light.

The X-ray absorption spectra (XAS) of Ar2 and ArNe dimers and small Ar clusters in the L2,3 region (244-252 eV) of the Ar atom have been recorded using synchrotron light and a combination of coincidence methods and kinetic energy discrimination of energetic ions. The absorption peaks in the spectra of the dimers and clusters were found to be shifted and broadened relative to the peaks in the spectrum of the Ar atom. In order to unambiguously relate these chemical shifts to the electronic structure of the core excited states in dimers, we performed ab initio calculations of the XAS spectra. Implications of the results for the use of XAS as a structure determination method in large rare gas clusters are discussed.

Excitation of HeNe by synchrotron light just below the frequency of the 1s → 3p transition of isolated He has been recently shown to be followed by resonant interatomic Coulombic decay (ICD). The vibrationally resolved widths of the ICD states were extracted with high precision from the photoion spectra. In this paper, we report the results of ab initio calculations of these widths. We show that interaction between electronic states at about the equilibrium distance of HeNe makes dark states of He accessible for the photoexcitation and subsequent electronic decay. Moreover, the values of the calculated widths are shown to be strongly sensitive to the presence of the non-adiabatic coupling between the electronic states participating in the decay. Therefore, only by considering the complete manifold of interacting decaying electronic states a good agreement between the measured and computed ICD widths can be achieved.