Interrupted orthodontic force results in less root resorption than continuous force in human premolars as measured by microcomputed tomography

Introduction. Root resorption is an undesirable but very frequently occurring sequel of orthodontic treatment. The aim of this study was to compare root resorption caused by either continuous (CF) or interrupted (IF) orthodontic force. Material and methods. The study was performed on human subjects on 30 first upper and lower premolars scheduled for extraction for orthodontic reasons. During four weeks before extraction 12 teeth were subjected to either CF or IF. The force was generated by a segmental titanium-molybdenum alloy cantilever spring that was activated in buccal direction. Initially a force of 60 CentiNewton was used in both CF and IF groups, the force in the former, however, was reactivated every week for 4 weeks. There was no reactivation of force in the IF group after initial application. A morphometric analysis of root resorption was performed by microcomputed tomography and the extent of tooth movement was measured on stone casts. Furthermore, a Tartarate-Resistant Acidic Phosphatase activity (TRAP), the marker enzyme of osteoclasts and cementoclasts, was determined by histochemical method. The Mann-Whitney U test was used to compare the difference in measured parameters between treatment and control tooth groups. Results. The number of resorption craters was significantly higher and their average volume almost twice as large in the CF compared to the IF group (p < 0.05). However, the distance of tooth displacement was similar for both groups. Cementoclasts were detected with the TRAP technique on the surface of two teeth only; both were subjected to continuous force. Conclusions. The use of IF leads to less destruction of root structure as opposed to continuous force while the same tooth movement was achieved

Angular deflection of rotary nickel titanium files: a comparative study

A new manufacturing method of twisting nickel titanium wire to produce rotary nickel titanium (RNT) files has recently been developed. The aim of the present study was to evaluate whether the new manufacturing process increased the angular deflection of RNT files, by comparing instruments produced using the new manufacturing method (Twisted Files) versus instruments produced with the traditional grinding process. Testing was performed on a total of 40 instruments of the following commercially available RNT files: Twisted Files (TF), Profile, K3 and M2 (NRT). All instruments tested had the same dimensions (taper 0.06 and tip size 25). Test procedures strictly followed ISO 3630-1. Data were collected and statistically analyzed by means ANOVA test. The results showed that TF demonstrated significantly higher average angular deflection levels (P<0.05), than RNT manufactured by a grinding process. Since angular deflection represent the amount of rotation (and consequently deformation) that a RNT file can withstand before torsional failure, such a significant improvement is a favorable property for the clinical use of the tested RNT files

Quality of canal obturation assessed by micro-computed tomography: Influence of filling technique and post placement in canals shaped with Reciproc

Abstract Aim To assess by micro-computed tomography (μCT) the quality of fillings in canals shaped with Reciproc considering the effects of filling technique and post insertion. Methodology The canals of 60 single-rooted teeth were instrumented with Reciproc R40 and randomly assigned to four groups (n = 15): G1, single point; G2, as G1 + DT Light Post; G3, continuous wave of condensation; G4, as G3 + DT Light Post. The filling voids were quantified by μCT. Data were statistically analysed by non-parametric test (p Results Filling greater than 96% of the entire canal volume was observed in all groups. The volume of internal voids was greater in G3 than in G4 (p Conclusions Our findings support the use of simplified techniques of canal shaping, filling with matching taper points and post cementation

Fracture resistance of endodontically treated teeth restored with a bulkfill flowable material and a resin composite

Aim. To determine and compare the fracture resistance of endodontically treated teeth restored with a bulk fill flowable material (SDR) and a traditional resin composite. Methods. Thirty maxillary and 30 mandibular first molars were selected based on similar dimensions. After cleaning, shaping and filling of the root canals and adhesive procedures, specimens were assigned to 3 subgroups for each tooth type (n=10): Group A: control group, including intact teeth; Group B: access cavities were restored with a traditional resin composite (EsthetX; Dentsply-Italy, Rome, Italy); Group C: access cavities were restored with a bulk fill flowable composite (SDR; Dentsply-Italy), except 1.5 mm layer of the occlusal surface that was restored with the same resin composite as Group B. The specimens were subjected to compressive force in a material static-testing machine until fracture occurred, the maximum fracture load of the specimens was measured (N) and the type of fracture was recorded as favorable or unfavorable. Data were statistically analyzed with one-way analysis of variance (ANOVA) and Bonferroni tests (P<0.05). Results. No statistically significant differences were found among groups (P<0.05). Fracture resistance of endodontically treated teeth restored with a traditional resin composite and with a bulk fill flowable composite (SDR) was similar in both maxillary and mandibular molars and showed no significant decrease in fracture resistance compared to intact specimens. Conclusions. No significant difference was observed in the mechanical fracture resistance of endodontically treated molars restored with traditional resin composite restorations compared to bulk fill flowable composite restorations

The Vascular flora of Mediterranean temporary wetlands in wikiplantbase #Sardegna

Mediterranean temporary wetlands are considered among the most biologically and biogeographically interesting ecosystems in the Mediterranean region so much to be defined “a floristic jewel”. Although a check list of vascular flora associated to these habitats is available for Sardinia, the information on species distribution is fragmented. Moreover many species are under-recorded because they are inconspicuous, exhibit a very short life cycle and are absent during unfavorable years, giving the impression that they have disappeared, whereas in fact they are still present in the soil seed-bank

Interconnection abutment fixture

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Nuovi e vecchi concetti in Endodonzia: il sistema Reciproc

RiassuntoObiettiviValutare il sigillo e la qualità dell'otturazione in canali sagomati con Reciproc in relazione a tecnica d'otturazione e inserimento del perno.Materiali e metodiSono stati analizzati con fluid filtration e microtomografia 44 denti estrattitrattati con Reciproc R40 e distinti in 4 gruppi test (n=10): G1, cono singolo; G2, come G1+perno; G3, System B; G4, come G3+perno (test parametrici e non, p<0,05).RisultatiIn tutti i gruppi le percentuali di riempimento canalare erano elevate. In G3 erano maggiori i vuoti interni vs. G4 (p<0,05) e l'infiltrazione finale vs. G1, G2 e G4 (p<0,05).ConclusioniLe analisi eseguite suffragano l'utilizzo di tecniche endodontiche semplificate e integrate di strumentazione, otturazione e ricostruzione.SummaryAimTo evaluate the apical seal and the quality of root filling in canals instrumented with Reciproc in relation to canal filling technique and post insertion.MethodologyFluid filtration test and microtomographic scan were performed on 44 extracted teeth instrumented with Reciproc R40 and divided into four test groups (n=10): G1, single cone; G2, as G1+post; G3, System B; G4, as G3+post (parametric and non-parametric tests, p<0.05).ResultsHigh percentages of canal filling were registered in all groups. In G3 the volume of internal voids and microleakage were greater than G4 (p<0.05) and G1, G2 e G4 (p<0.05), respectively.ConclusionsOur results support the use of simplified integrated endodontic techniques of instrumentation, filling and reconstruction

SARS-CoV-2 susceptibility and COVID-19 disease severity are associated with genetic variants affecting gene expression in a variety of tissues

Variability in SARS-CoV-2 susceptibility and COVID-19 disease severity between individuals is partly due to genetic factors. Here, we identify 4 genomic loci with suggestive associations for SARS-CoV-2 susceptibility and 19 for COVID-19 disease severity. Four of these 23 loci likely have an ethnicity-specific component. Genome-wide association study (GWAS) signals in 11 loci colocalize with expression quantitative trait loci (eQTLs) associated with the expression of 20 genes in 62 tissues/cell types (range: 1:43 tissues/gene), including lung, brain, heart, muscle, and skin as well as the digestive system and immune system. We perform genetic fine mapping to compute 99% credible SNP sets, which identify 10 GWAS loci that have eight or fewer SNPs in the credible set, including three loci with one single likely causal SNP. Our study suggests that the diverse symptoms and disease severity of COVID-19 observed between individuals is associated with variants across the genome, affecting gene expression levels in a wide variety of tissue types

A first update on mapping the human genetic architecture of COVID-19

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