Strain controlled oxygen vacancy formation and ordering in CaMnO3_3

We use first-principles calculations to investigate the stability of bi-axially strained \textit{Pnma} perovskite CaMnO$_3$ towards the formation of oxygen vacancies. Our motivation is provided by promising indications that novel material properties can be engineered by application of strain through coherent heteroepitaxy in thin films. While it is usually assumed that such epitaxial strain is accommodated primarily by changes in intrinsic lattice constants, point defect formation is also a likely strain relaxation mechanism. This is particularly true at the large strain magnitudes ($>$4%) which first-principles calculations often suggest are required to induce new functionalities. We find a strong dependence of oxygen vacancy defect formation energy on strain, with tensile strain lowering the formation energy consistent with the increasing molar volume with increasing oxygen deficiency. In addition, we find that strain differentiates the formation energy for different lattice sites, suggesting its use as a route to engineering vacancy ordering in epitaxial thin films.Comment: 7 pages, 7 figure

Influence of the shape of artificial canals on the fatigue resistance of NiTi rotary instruments

To investigate the influence of the trajectory of NiTi rotary instruments on the outcome of cyclic fatigue tests. Ten ProFile and Mtwo instruments tip size 20, taper 0.06 and tip size 25, taper 0.06 were tested in two simulated root canals with an angle of curvature of 60 degrees and radius of curvature of 5 mm but with different shape. Geometrical analysis of the angle and radius of the curvature that each instrument followed inside the two different artificial canals was performed on digital images. The instruments were then rotated until fracture at a constant speed of 300 rpm to calculate the number of cycles to failure (NCF) and the length of the fractured fragment. Mean values were calculated and analysed using two different multivariate linear regression models and an independent sample t-test. The shape of the artificial root canal used in cyclic fatigue studies influenced the trajectory of the instrument. This difference is reflected by the NCF measured for the same instrument in the different artificial root canals and by the impact of the type of canal on both the NCF (St.beta = 0.514) and fragment length (St.beta = -0.920). Small variations in the geometrical parameters of the curvature of an instrument subjected to flexural fatigue could have a significant influence on the results of fatigue tests

Efficacy of sonic and ultrasonic irrigation devices in the removal of debris from canal irregularities in artificial root canals

Objective: To evaluate the efficacy of different sonic and ultrasonic devices in the elimination of debris from canal irregularities in artificial root canals. Materials and Methods: A resin model of a transparent radicular canal filled with dentin debris was used. Five groups were tested, namely: Group 1 – ultrasonic insert 15.02; Group 2 – ultrasonic insert 25/25 IRRI K; Group 3 – ultrasonic insert 25/25 IRRI S; Group 4 – sonic insert 20/28 Eddy on a vibrating sonic air-scaler handpiece; Group 5 – 20.02 K-file inserted on a Safety M4 handpiece. Two different irrigants (5% sodium hypochlorite and 17% EDTA) and 3 different times of activation (20, 40, and 60 seconds) were tested. Means and standard deviations were calculated and statistically analyzed with the Kruskal-Wallis and Wilcoxon tests (p<0.05). Results: No statistically significant differences were found between the two irrigants used. Group 4 removed more debris than the other groups (p<0.05). Groups 1, 2, and 3 removed more debris than group 5 (p<0.05). A statistically significant difference (p<0.05) was found for the time of activation in all groups and at all canal levels, except between 40 and 60 seconds in group 4 at coronal and middle third level (p>0.05). Conclusions: No significant differences were found between 5% sodium hypochlorite and 17% EDTA. When the time of activation rises, the dentin debris removal increases in all groups. Both sonic and ultrasonic activation demonstrate high capacity for dentin debris removal

Efficacy of sonic and ultrasonic irrigation devices in the removal of debris from root canal irregularities in artificial root canals

Objective: to evaluate the efficacy of different sonic and ultrasonic devices in the elimination of debris from canal irregularities in artificial root canals. Materials and Methods: a resin model of a transparent radicular canal filled with dentin debris was used. Five groups were tested, namely: Group 1 - ultrasonic insert 15.02; Group 2 - ultrasonic insert 25/25 IRRI K; Group 3 - ultrasonic insert 25/25 IRRI S; Group 4 - sonic insert 20/28 Eddy on a vibrating sonic air-scaler handpiece; Group 5 - 20.02 K-file inserted on a Safety M4 handpiece. Two different irrigants (5% sodium hypochlorite and 17% EDTA) and 3 different times of activation (20, 40, and 60 seconds) were tested. Means and standard deviations were calculated and statistically analyzed with the Kruskal-Wallis and Wilcoxon tests (p0.05). Conclusions: no significant differences were found between 5% sodium hypochlorite and 17% EDTA. When the time of activation rises, the dentin debris removal increases in all groups. Both sonic and ultrasonic activation demonstrate high capacity for dentin debris removal

In vitro Evaluation of the Cytotoxicity of Different Root Canal Filling Materials

Objective: Aim of the present study was to evaluate the cytotoxicity of Real Seal 1 compared to other commercially available endodontic filling materials: Real Seal (SybronEndo, Orange, CA, USA) and Thermafil (Tulsa Dental, Tulsa, OK, USA). Material and Methods: Periodontal ligament cells from healthy patients were cultured. The eluate of Real Seal 1TM (RS1), Real Seal (RS) and Thermafil (TF) samples was used for the cells viability tests, both diluted (50%) or undiluted (100%). Incubation of the specimens was performed in culture medium for 24 h, 48 h and 72 h at 37 °C under sterile conditions. The cellular mortality was evaluated by MTT test. Results were statistically analysed and the statistical significance was set at p< 0.05. Results: None of the studied materials showed toxic effects during the period of observation (0 -72 h) when compared to the control group. Only RS induced a very modest increase in cell mortality (about 3% at both concentrations used, during the first 24 hours), when increasing the incubation time, however, only the lower concentration continued to show modest toxicity. Conclusions: Results of the present study showed that all tested materials did not exhibit cytotoxic effects when compared to the control group. © Gambarini et al

Fatica ciclica di nuovi strumenti al nichel-titanio in canali artificiali a singola e doppia curvatura

RiassuntoObiettiviLo studio si pone lo scopo di valutare la resistenza a fatica ciclica di due tipologie di strumenti in nichel-titanioMateriali e metodiOttanta canali a singola curvatura e a doppia curvatura sono stati strumenti suddivisi in 4 gruppi: GTX 30/.06, GTX 40/.04, Twisted Files 30/.06 e Twisted Files 40/.04. È stato calcolato il numero di cicli a frattura (NCF).RisultatiGli strumenti dei gruppi Twisted Files hanno resistito più a lungo in rotazione nei diversi canali artificiali (p≤0,05). Le dimensioni dello strumento non hanno avuto un'influenza statisticamente significativa.ConclusioniI risultati di questo studio indicano che la doppia curvatura canalare a "S" aumenta notevolmente il rischio di frattura e il gruppo Twisted Files è risultato più resistente rispetto al gruppo GTX.SummaryObjectivesAim of this study was to evaluate the cyclic fatigue resistance of two types of new nickel-titanium endodontic instrumentsMaterials and methods80 instruments divided into 4 groups (20 each group), GTX 30/.06, GTX 40/.04, Twisted Files 30/.06, Twisted Files 40/.04. All the instruments were tested in two different artificial canals, one with a single curvature and the other with a double curvature. All instruments were rotated until fracture and the number of cycles to fracture (NCF) was then calculated,ResultsTwisted Files instruments resisted longer in rotation in the different canals. The size of the instrument (30.06, 40.04) did not have a statistically significant influence.ConclusionsThe instruments Twisted Files were more resistant to cyclic fatigue compared to the GTX

Influenza della sterilizzazione su strumenti fabbricati con leghe trattate termicamente

RiassuntoObiettiviDi recente sono stati proposti in endodonzia innovativi processi di produzione di leghe con trattamenti termici. Scopo di questo studio è stato di valutare l'effetto di vari cicli di sterilizzazione in autoclave sulla resistenza alla fatica ciclica di strumenti endodontici rotanti realizzati con leghe nichel-titanio (Ni-Ti) trattate termicamente.Materiali e metodiSono stati selezionati tre gruppi (n=24) di strumenti in Ni-Ti di taglia 04.40 K3, in lega Ni-Ti tradizionale, Vortex, in lega M-Wire e K3 XT prototipi in lega TF. Ogni gruppo è stato poi suddiviso in due sottogruppi (A e B) composti rispettivamente da strumenti non sterilizzati e strumenti sterilizzati in autoclave per 10 cicli a 134°. Tutti i 72 strumenti sono infine stati testati per fatica, valutando il numero di cicli a frattura (NCF). I dati sono stati raccolti e analizzati statisticamente (ANOVA).RisultatiGli strumenti K3 XT hanno mostrato una resistenza alla fatica ciclica significativamente maggiore (p<0,05) rispetto a tutti gli altri strumenti. Inoltre, sono state notate differenze statisticamente significative tra i file K3 XT sterilizzati e non sterilizzati (762 vs 651 NCF), mentre gli altri due tipi di strumento non hanno mostrato differenze rilevanti in seguito ai cicli di sterilizzazione (524 vs 539 K3, 454 vs 480 Vortex).ConclusioniPoiché i K3 e i K3 XT sono identici nel disegno e si differenziano solo per il trattamento termico, si può ipotizzare un'influenza positiva dell'apporto termico, come quello derivante da sterilizzazione in autoclave, in alcune leghe trattate termicamente.SummaryObjectivesRecently, innovative processes of production of alloys with thermal treatment have been proposed in endodontics. The aim of this study was to evaluate the effect of various cycles of autoclave sterilization on cyclic fatigue resistance of rotary endodontic instruments, made of heat-treated nickel-titanium (Ni-Ti) alloys.Materials and methodsThree groups (n=24) of Ni-Ti instruments with the same size (04.40) were selected: K3 (traditional Ni-Ti alloy), Vortex (M-Wire alloy) and K3 XT prototype (TF alloy). Each group was then divided into two subgroups comprising respectively non-sterilized instruments and instruments sterilized in an autoclave for 10 cycles at 134°. All 72 instruments were finally tested for fatigue, considering the number of cycles to fracture (NCF). Data were collected and analyzed statistically (ANOVA).ResultsThe instruments K3 XT showed significantly higher resistance to cyclic fatigue than all other instruments. Statistically significant differences (p<0.05) were also noted among the files K3 XT sterilized and unsterilized (762 vs 651 NCF), while the other two types of instrument did not show significant differences as a result of sterilization cycles (524 vs 539 K3, 454 vs 480 Vortex).ConclusionsGiven that K3 and K3 XT are identical in design and differ only in the heat treatment, a positive influence of heat treatment, such as the one caused by autoclaving, can be hypothesized

Textbook outcome in urgent early cholecystectomy for acute calculous cholecystitis: results post hoc of the S.P.Ri.M.A.C.C study

Introduction: A textbook outcome patient is one in which the operative course passes uneventful, without complications, readmission or mortality. There is a lack of publications in terms of TO on acute cholecystitis. Objetive: The objective of this study is to analyze the achievement of TO in patients with urgent early cholecystectomy (UEC) for Acute Cholecystitis. and to identify which factors are related to achieving TO. Materials and methods: This is a post hoc study of the SPRiMACC study. It ́s a prospective multicenter observational study run by WSES. The criteria to define TO in urgent early cholecystectomy (TOUEC) were no 30-day mortality, no 30-day postoperative complications, no readmission within 30&nbsp;days, and hospital stay ≤ 7&nbsp;days (75th percentile), and full laparoscopic surgery. Patients who met all these conditions were taken as presenting a TOUEC. Outcomes: 1246 urgent early cholecystectomies for ACC were included. In all, 789 patients (63.3%) achieved all TOUEC parameters, while 457 (36.6%) failed to achieve one or more parameters and were considered non-TOUEC. The patients who achieved TOUEC were younger had significantly lower scores on all the risk scales analyzed. In the serological tests, TOUEC patients had lower values for in a lot of variables than non-TOUEC patients. The TOUEC group had lower rates of complicated cholecystitis. Considering operative time, a shorter duration was also associated with a higher probability of reaching TOUEC. Conclusion: Knowledge of the factors that influence the TOUEC can allow us to improve our results in terms of textbook outcome

Colorectal Cancer Stage at Diagnosis Before vs During the COVID-19 Pandemic in Italy

IMPORTANCE Delays in screening programs and the reluctance of patients to seek medical attention because of the outbreak of SARS-CoV-2 could be associated with the risk of more advanced colorectal cancers at diagnosis. OBJECTIVE To evaluate whether the SARS-CoV-2 pandemic was associated with more advanced oncologic stage and change in clinical presentation for patients with colorectal cancer. DESIGN, SETTING, AND PARTICIPANTS This retrospective, multicenter cohort study included all 17 938 adult patients who underwent surgery for colorectal cancer from March 1, 2020, to December 31, 2021 (pandemic period), and from January 1, 2018, to February 29, 2020 (prepandemic period), in 81 participating centers in Italy, including tertiary centers and community hospitals. Follow-up was 30 days from surgery. EXPOSURES Any type of surgical procedure for colorectal cancer, including explorative surgery, palliative procedures, and atypical or segmental resections. MAIN OUTCOMES AND MEASURES The primary outcome was advanced stage of colorectal cancer at diagnosis. Secondary outcomes were distant metastasis, T4 stage, aggressive biology (defined as cancer with at least 1 of the following characteristics: signet ring cells, mucinous tumor, budding, lymphovascular invasion, perineural invasion, and lymphangitis), stenotic lesion, emergency surgery, and palliative surgery. The independent association between the pandemic period and the outcomes was assessed using multivariate random-effects logistic regression, with hospital as the cluster variable. RESULTS A total of 17 938 patients (10 007 men [55.8%]; mean [SD] age, 70.6 [12.2] years) underwent surgery for colorectal cancer: 7796 (43.5%) during the pandemic period and 10 142 (56.5%) during the prepandemic period. Logistic regression indicated that the pandemic period was significantly associated with an increased rate of advanced-stage colorectal cancer (odds ratio [OR], 1.07; 95%CI, 1.01-1.13; P = .03), aggressive biology (OR, 1.32; 95%CI, 1.15-1.53; P &lt; .001), and stenotic lesions (OR, 1.15; 95%CI, 1.01-1.31; P = .03). CONCLUSIONS AND RELEVANCE This cohort study suggests a significant association between the SARS-CoV-2 pandemic and the risk of a more advanced oncologic stage at diagnosis among patients undergoing surgery for colorectal cancer and might indicate a potential reduction of survival for these patients